Modern Operative Dentistry: Principles for Clinical Practice [1st ed. 2020] 978-3-030-31771-3, 978-3-030-31772-0

Table of contents :
Front Matter ....Pages I-XIII
Diagnosis and Treatment Planning (Carlos Rocha Gomes Torres, Anna Greta Barbe, Michael Johannes Noack, Michael Jochen Wicht)....Pages 1-42
Ergonomics Principles Applied to the Dental Clinic (Karen Cristina Kazue Yui, Cristiani Siqueira Barbosa Lencioni, Eliel Soares Orenha, Carlos Rocha Gomes Torres)....Pages 43-76
Cariology (Taciana Marco Ferraz Caneppele, Alessandra Bühler Borges, Carlos Rocha Gomes Torres, José Roberto Rodrigues, Thomas Attin)....Pages 77-121
Instruments and Equipments (Sergio Eduardo de Paiva Gonçalves, Cesar Rogério Pucci, Carlos Rocha Gomes Torres, Anuradha Prakki)....Pages 123-165
Nomenclature and Classification of Cavities and Tooth Preparations (Carlos Rocha Gomes Torres, Ana Carolina Botta)....Pages 167-182
General Principles of Tooth Preparation and Carious Tissue Removal (Carlos Rocha Gomes Torres, Falk Schwendicke)....Pages 183-221
Isolation of the Operating Field (Alessandra Bühler Borges, Carlos Rocha Gomes Torres, Ana Raquel Benetti, Azam Bakhshandeh)....Pages 223-260
Matrix and Wedge Systems (Cesar Rogério Pucci, Carlos Rocha Gomes Torres, Ali Ibrahim Abdalla)....Pages 261-288
Protection of the Dentin-Pulp Complex (Adriana Cristina de Mello Torres, Ana Paula Martins Gomes, Claudio Hideki Kubo, Carlos Rocha Gomes Torres)....Pages 289-333
Tooth Preparations for Amalgam Restorations (Carlos Rocha Gomes Torres, Deepak Mehta)....Pages 335-371
Amalgam Restorations (Carlos Rocha Gomes Torres, Shankargouda Patil, Graziela Ribeiro Batista)....Pages 373-409
Extensive Amalgam Restorations (Carlos Rocha Gomes Torres, Shilpa Hanamaraddi Bhandi, João Cândido de Carvalho)....Pages 411-433
Light-Curing Units (Nicola Scotti, Andrea Baldi, Edoardo Alberto Vergano, Claudio Hideki Kubo, Carlos Rocha Gomes Torres)....Pages 435-464
Composite Restoration on Anterior Teeth (Carlos Rocha Gomes Torres, Rayssa Ferreira Zanatta)....Pages 465-575
Composite Restoration on Posterior Teeth (Carlos Rocha Gomes Torres, Marcelo Balsamo, Satoshi Imazato)....Pages 577-630
Preventive Measures and Minimally Invasive Restorative Procedures (Alessandra Bühler Borges, Carlos Rocha Gomes Torres, Nadine Schlueter)....Pages 631-666
Aesthetic Veneers: What Are They and How to Handle Them? (Maria Filomena Rocha Lima Huhtala, Clovis Pagani, Carlos Rocha Gomes Torres, Pekka Kalevi Vallittu, Jukka Pekka Matinlinna)....Pages 667-690
Dentin Hypersensitivity and Cracked Teeth (Eduardo Bresciani, Carlos Rocha Gomes Torres, Annette Wiegand)....Pages 691-704
Back Matter ....Pages 705-715

Citation preview

Textbooks in Contemporary Dentistry

Carlos Rocha Gomes Torres   Editor

Modern Operative Dentistry Principles for Clinical Practice

Textbooks in Contemporary Dentistry

This textbook series presents the most recent advances in all fields of dentistry, with the aim of bridging the gap between basic science and clinical practice. It will equip readers with an excellent knowledge of how to provide optimal care reflecting current understanding and utilizing the latest materials and techniques. Each volume is written by internationally respected experts in the field who ensure that information is conveyed in a concise, consistent, and readily intelligible manner with the aid of a wealth of informative illustrations. Textbooks in Contemporary Dentistry will be especially valuable for advanced students, practitioners in the early stages of their career, and university instructors. More information about this series at http://www.­springer.­com/series/14362

Carlos Rocha Gomes Torres Editor

Modern Operative Dentistry Principles for Clinical Practice

Editor Carlos Rocha Gomes Torres Institute of Science and Technology São Paulo State University – UNESP São Paulo, Brazil

The Work is based on a Portuguese language edition that has been first published in 2013 by Santos Editora, São Paulo with the following title: Odontologia Restauradora Estética e Funcional: Princípios para a Prática Clínica ISSN 2524-4612     ISSN 2524-4620 (electronic) Textbooks in Contemporary Dentistry ISBN 978-3-030-31771-3    ISBN 978-3-030-31772-0 (eBook) https://doi.org/10.1007/978-3-030-31772-0 © Springer Nature Switzerland AG 2020 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

V

To my wife, Adriana Cristina de Mello Torres, and to my daughter, Letícia de Mello Torres, who participated on my daily battle to finish this work, being always by my side, giving me support at all moments and strength to persevere. To my parents, Alfredo Gomes Torres Filho (in memoriam) and Josepha Rocha Gomes Torres, who always motivated me to study, to work, and to never give up. You were always an example to be followed. To my sister, Sonia Rocha Gomes Torres, the person who introduced me the dentistry and inspired me to follow this path, which brought me lots of satisfaction and professional fulfillment. Thank you for your support on many important moments of my life. Carlos Rocha Gomes Torres

Foreword The discipline of Operative Dentistry on São José dos Campos Dental School was created in 1973 and is now more than 45 years. During this time, its growth and consolidation are evident, which resulted from the hard work of its pioneers, who with different personal characteristics, on hard times and with rudimentary technology, were able to conduct and improve it. In relation to that, it is important to highlight the names of these distinguished professors: Newton José Giachetti, Delcio Pasin, José Benedicto de Mello, and João Cândido de Carvalho. Many difficulties were overcome, but the lemma of the discipline has always been the dedication to the students, offering them quality of knowledge, modern approaches, and evidence based on the dental research results. Other differential from the discipline, which prevails until today, is the respect and harmony among professors and staff, maintaining a pleasant and favorable environment. Since 1992, the discipline has a postgraduation program in Restorative Dentistry, which has already prepared hundreds of masters and doctors who now occupy important positions in Brazilian and international universities. To write the foreword of this book, created by the current professors of the Operative Dentistry discipline, makes me very proud, because it is an example of great professional work.

This book, edited by Prof. Carlos Rocha Gomes Torres and contributors, comes to improve the available dental literature, adding new points of view, with chapters correlating important dental specialties. Some chapters talk about classic topics like cariology, diagnosis, prevention, instruments and equipment, restorative techniques with different materials, and dental hypersensitivity, besides principles of ergonomics, so essential to the clinical practice. The content is based on a vast literature and the experience of the professors. The chapters are illustrated with schematic drawings and pictures of the clinical cases, allowing the readers a better understanding about the techniques and procedures described on the text. I consider that this book assembles valuable information for the dentists. It represents the competent work from a group of professors from the Institute of Science and Technology of São José dos Campos, School of Dentistry, that with great care share their knowledge. Before ending, I would like to mention part of a poem from Dom Helder Camara that says:

»» More important than gain roads, cross seas or reach supersonic speed, it is important to open yourself to the others, discover them and go toward their direction.

Maria Amélia Máximo de Araujo

Full Professor of Operative Dentistry Institute of Science and Technology, São Paulo State University – UNESP, São Paulo, Brazil

VII

Preface Perhaps, the work of an educator is one that can bring more satisfaction to a human being. The opportunity to transmit what we have learned to many people, who will use that information throughout their lives, makes us feel that we are doing something meaningful. Since the beginning of my career as a university professor, I tried to improve the assimilation of knowledge by the students, using different strategies in several ways, to teach specific subjects of dentistry, some of which are extremely complex. Despite the content of my lectures, at the end, I was frequently asked by the students the same question: “Professor, which book should I use to study that subject?” However, the topics and content presented in a lecture come from many different sources, such as those we learned from our own professors, from several books and papers we read, and even from our own professional experiences. Therefore, the answer to that question was always very hard. That inspired me to start creating this book. On my everyday professional life, I have the opportunity to follow students from their first contact with Operative Dentistry discipline. It is necessary to transmit them from basic knowledge about nomenclature of cavities and principles of tooth preparation to the most advanced information, such as aesthetics analyses and restorative techniques. The idea of this book is to offer, in a single place, all the basic information necessary for a student, which is starting his studies about Dentistry to perform different types of direct dental restorations. The content of this book also aims to help the clinicians who desire to update their knowledge, improving the quality of the treatments they perform.

The diagnosis of different dental problems is presented, teaching how to create an accurate treatment plan for the patients. The cariology is discussed, in a way to give the reader a broad knowledge about the etiology of caries disease, as well the invasive and noninvasive treatment indication. The dentist must keep in mind that success in Operative Dentistry is only possible if associated with the preventive dentistry. In other words, the restorations should be considered part of the caries disease treatment and not the treatment by itself. The ergonomics principles for dentistry were added, because it is on the Operative Dentistry discipline that students start to practice dental treatments and should learn how to sit and work in a healthy way. Lack of information at this moment can lead to acquisition of deleterious habits, which will negatively affect the dentist´s health. The noncarious-related tooth sensitivity, mainly dentin hypersensitivity and cracked tooth syndrome, were also approached, trying to help the dentists on the difficult diagnosis of those conditions. This book would not be possible without the partnership of many colleagues, professors, and experts from the Institute of Science and Technology of Sao Paulo State University (UNESP) and from other 19 dental schools around the world, of 13 different countries, who joined the project and make it possible. With the support of all, several years of intensive work, awaken nights, and extra work on weekends and holidays, the book was concluded. I hope that it can contribute for the professional life of all readers. Carlo Rocha Gomes Torres

São Jose dos Campos, São Paulo, Brazil

Acknowledgments To the Institute of Science and Technology of São Paulo State University (UNESP) at São José dos Campos City, which welcomed me with open arms and gave me all the opportunities and support to obtain my bachelor and PhD degrees. To the current and retired professors of São José dos Campos School of Dentistry, who throughout the years, with hard work and a lot of devotion, created and developed this renowned school that I am honored to belong and always with willingness transmitted their knowledge for hundreds of students graduated as dentists. To the secretary and technicians of the Restorative Dentistry Department, Rosângela da Silva de Melo, Liliane Marques Franchitto, Fernanda Maria de Brito Cunha and Josiana Maria Alves Carneiro, for their daily support on my professional activities. To my colleagues’ professors of Operative Dentistry, Sergio Eduardo de Paiva Goncalves, Maria Filomena Rocha Lima Huhtala, José Roberto Rodrigues, Cesar Rogério Pucci, Clóvis Pagani, Claudio Hideki Kubo, Taciana Marco Ferraz Caneppele, Karen Cristina Kazue Yui, and Eduardo Bresciani, for the constant support during the years dedicated to the preparation of this book. To my colleague’s professor, Alessandra Buhler Borges, whose support and encouragement were essential to conclude this book. To the retired professors of Operative Dentistry, Newton José Giachetti, Delcio Pasin (in memoriam), José Benedicto de Mello, João Candido de Carvalho, Regina Célia dos Santos Pinto Silva, and Rosehelene Marotta Araújo. I hope that this book is consistent with the legacy left by you. To the librarians of the Institute of Science and Technology for their support to this work, specially to Maria das Dores Nogueira, who was always willing to help me, since my days as undergraduate student. To our former undergraduate and graduate students, who contributed to obtain some pictures used in many chapter´s illustration.

To the patients of Operative Dentistry Clinic, who kindly permitted to use those pictures obtained during their treatment in this book. To the contributors from other universities, Doctors Ali Ibrahim Abdalla (University of Tanta, Egypt), Ana Carolina Botta (Stony Brook School of Dental Medicine, USA), Andrea Baldi (University of Turin, Italy), Anna Greta Barbe (University of Cologne, Germany), Ana Raquel Benetti (University of Copenhagen, Denmark), Annette Wiegand (University of Göttingen, Germany), Anuradha Prakki (University of Toronto, Canada), Azam Bakhshandeh (University of Copenhagen, Denmark), Deepak Mehta (V. S. Dental College & Hospital, India), Edoardo Alberto Vergano (University of Turin, Italy), Eliel Soares Orenha (Sao Paulo University, Brazil), Falk Schwendicke (Charité University Berlin, Germany), Graziela Ribeiro Batista (A.T. Still University, USA), Jukka Pekka Matinlinna (University of Hong Kong), Michael J.  Noack (University of Cologne, Germany), Michael J. Wicht (University of Cologne, Germany), Nadine Schlueter (University of Freiburg, Germany), Nicola Scotti (University of Turin, Italy), Pekka Vallittu (University of Turku, Finland), Rayssa Ferreira Zanatta (University of Taubate, Brazil), Satoshi Imazato (University of Osaka, Japan), Shankargouda Patil (Jazan University, Saudi Arabia), Shilpa H. Bhandi (Jazan University, Saudi Arabia), and Thomas Attin (University of Zurich, Switzerland), experts on their field, who shared their knowledge to improve the different chapters. To Professor Rayssa Ferreira Zanatta for her outstanding work on the bibliography organization of all chapters. To Professor Shankargouda Patil for his inestimable partnership and support, since the first idea of translating and publishing this book into the English language. To Professor Maria Amelia Maximo de Araujo, who inspired me to become a professor and was my advisor during undergraduate and postgraduate training. Without her presence in my life, I certainly would not be a professor and have the privilege to teach others what I learned. Thanks for the friendship and support during all these years.

IX

Contents 1

Diagnosis and Treatment Planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Carlos Rocha Gomes Torres, Anna Greta Barbe, Michael Johannes Noack, and Michael Jochen Wicht

2

Ergonomics Principles Applied to the Dental Clinic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Karen Cristina Kazue Yui, Cristiani Siqueira Barbosa Lencioni, Eliel Soares Orenha, and Carlos Rocha Gomes Torres

3 Cariology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Taciana Marco Ferraz Caneppele, Alessandra Bühler Borges, Carlos Rocha Gomes Torres, José Roberto Rodrigues, and Thomas Attin 4

Instruments and Equipments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 Sergio Eduardo de Paiva Gonçalves, Cesar Rogério Pucci, Carlos Rocha Gomes Torres, and Anuradha Prakki

5

Nomenclature and Classification of Cavities and Tooth Preparations . . . . . . . . . . . . . . . . . . . . 167 Carlos Rocha Gomes Torres and Ana Carolina Botta

6

General Principles of Tooth Preparation and Carious Tissue Removal . . . . . . . . . . . . . . . . . . . . 183 Carlos Rocha Gomes Torres and Falk Schwendicke

7

Isolation of the Operating Field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 Alessandra Bühler Borges, Carlos Rocha Gomes Torres, Ana Raquel Benetti, and Azam Bakhshandeh

8

Matrix and Wedge Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261 Cesar Rogério Pucci, Carlos Rocha Gomes Torres, and Ali Ibrahim Abdalla

9

Protection of the Dentin-Pulp Complex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289 Adriana Cristina de Mello Torres, Ana Paula Martins Gomes, Claudio Hideki Kubo, and Carlos Rocha Gomes Torres

10

Tooth Preparations for Amalgam Restorations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335 Carlos Rocha Gomes Torres and Deepak Mehta

11

Amalgam Restorations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373 Carlos Rocha Gomes Torres, Shankargouda Patil, and Graziela Ribeiro Batista

12

Extensive Amalgam Restorations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 411 Carlos Rocha Gomes Torres, Shilpa Hanamaraddi Bhandi, and João Cândido de Carvalho

13

Light-Curing Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435 Nicola Scotti, Andrea Baldi, Edoardo Alberto Vergano, Claudio Hideki Kubo, and Carlos Rocha Gomes Torres

14

Composite Restoration on Anterior Teeth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 465 Carlos Rocha Gomes Torres and Rayssa Ferreira Zanatta

15

Composite Restoration on Posterior Teeth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 577 Carlos Rocha Gomes Torres, Marcelo Balsamo, and Satoshi Imazato

X

Contents

16

Preventive Measures and Minimally Invasive Restorative Procedures . . . . . . . . . . . . . . . . . . . . 631 Alessandra Bühler Borges, Carlos Rocha Gomes Torres, and Nadine Schlueter

17

Aesthetic Veneers: What Are They and How to Handle Them? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 667 Maria Filomena Rocha Lima Huhtala, Clovis Pagani, Carlos Rocha Gomes Torres, Pekka Kalevi Vallittu, and Jukka Pekka Matinlinna

18

Dentin Hypersensitivity and Cracked Teeth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 691 Eduardo Bresciani, Carlos Rocha Gomes Torres, and Annette Wiegand



Supplementary Information Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 707

XI

Contributors Ali Ibrahim Abdalla

Shilpa Hanamaraddi Bhandi

Department of Restorative Dentistry Faculty of Dentistry, Tanta University Tanta, Egypt [email protected]

Department of Restorative Dental Sciences Faculty of Dentistry, Jazan University Shwajra, Jazan, Saudi Arabia [email protected]

Thomas Attin

Alessandra Bühler Borges

Clinic of Conservative and Preventive Dentistry Center of Dental Medicine, University of Zurich Zurich, Switzerland [email protected]

Department of Restorative Dentistry Institute of Science and Technology of São Jose dos Campos, São Paulo State University – UNESP São Jose dos Campos, São Paulo, Brazil [email protected]

Azam Bakhshandeh Department of Odontology, Section of Cariology and Endodontics & Section of Oral Radiology Faculty of Health and Medical Sciences University of Copenhagen Copenhagen, Denmark [email protected]

Ana Carolina Botta

Andrea Baldi

Eduardo Bresciani

Department of Cariology and Operative Dentistry Dental School Lingotto, University of Turin Turin, Italy [email protected]

Department of Restorative Dentistry Institute of Science and Technology of São Jose dos Campos, São Paulo State University – UNESP São Jose dos Campos, São Paulo, Brazil [email protected]

Division of Operative and Dental Materials Department of General Dentistry Stony Brook School of Dental Medicine Stony Brook, NY, USA [email protected]

Marcelo Balsamo Private Practice in Esthetic Dentistry Technical consultant of Voco GmBh Dental materials São Paulo, São Paulo, Brazil [email protected]

Anna Greta Barbe Department of Operative Dentistry and Periodontology University Hospital, University of Cologne Cologne, Germany [email protected]

Graziela Ribeiro Batista Missouri School of Dentistry and Oral Health A.T. Still University Kirksville, MO, USA [email protected]

Ana Raquel Benetti Department of Odontology, Section of Dental Materials Faculty of Health and Medical Sciences University of Copenhagen Copenhagen, Denmark [email protected]

Taciana Marco Ferraz Caneppele Department of Restorative Dentistry Institute of Science and Technology of São Jose dos Campos, São Paulo State University – UNESP São Jose dos Campos, São Paulo, Brazil [email protected]

João Cândido de Carvalho Department of Restorative Dentistry Institute of Science and Technology of São Jose dos Campos, São Paulo State University – UNESP São Jose dos Campos, São Paulo, Brazil [email protected]

Adriana Cristina de Mello Torres Department of Restorative Dentistry Institute of Science and Technology of São Jose dos Campos, São Paulo State University – UNESP São Jose dos Campos, São Paulo, Brazil [email protected]

XII

Contributors

Sergio Eduardo de Paiva Gonçalves

Michael Johannes Noack

Department of Restorative Dentistry Institute of Science and Technology of São Jose dos Campos, São Paulo State University – UNESP São Jose dos Campos, São Paulo, Brazil [email protected]

Department of Operative Dentistry and Periodontology University Hospital, University of Cologne Cologne, Germany [email protected]

Eliel Soares Orenha Ana Paula Martins Gomes Department of Restorative Dentistry Institute of Science and Technology of São Jose dos Campos, São Paulo State University – UNESP São Jose dos Campos, São Paulo, Brazil [email protected]

Department of Pediatric Dentistry, Orthodontics, and Community Dental Health Bauru School of Dentistry, Sao Paulo University – USP Bauru, São Paulo, Brazil [email protected]

Clovis Pagani Maria Filomena Rocha Lima Huhtala Department of Restorative Dentistry Institute of Science and Technology of São Jose dos Campos, São Paulo State University – UNESP São Jose dos Campos, São Paulo, Brazil [email protected]

Department of Restorative Dentistry Institute of Science and Technology of São Jose dos Campos, São Paulo State University – UNESP São Jose dos Campos, São Paulo, Brazil [email protected]

Shankargouda Patil Satoshi Imazato Department of Biomaterials Science Graduate School of Dentistry, Osaka University Osaka, Japan [email protected]

Department of Maxillofacial Surgery and Diagnostic Sciences, Faculty of Dentistry, Jazan University Shwajra, Jazan, Saudi Arabia [email protected]

Anuradha Prakki Claudio Hideki Kubo Department of Restorative Dentistry Institute of Science and Technology of São Jose dos Campos, São Paulo State University – UNESP São Jose dos Campos, São Paulo, Brazil [email protected]

Cristiani Siqueira Barbosa Lencioni Department of Restorative Dentistry Institute of Science and Technology of São Jose dos Campos, São Paulo State University – UNESP São Jose dos Campos, São Paulo, Brazil [email protected]

Jukka Pekka Matinlinna Dental Materials Science, Applied Oral Sciences & Community Dental Care, Faculty of Dentistry The University of Hong Kong, Prince Philip Dental Hospital Sai Ying Pun, Hong Kong SAR, China [email protected]

Deepak Mehta Department of Conservative Dentistry and Endodontics Vokkaligara Sangha Dental College and Hospital Bangalore, India [email protected]

Dental Research Institute, Faculty of Dentistry University of Toronto Toronto, ON, Canada [email protected]

Cesar Rogério Pucci Department of Restorative Dentistry Institute of Science and Technology of São Jose dos Campos, São Paulo State University – UNESP São Jose dos Campos, São Paulo, Brazil [email protected]

José Roberto Rodrigues Department of Restorative Dentistry Institute of Science and Technology of São Jose dos Campos, São Paulo State University – UNESP São Jose dos Campos, São Paulo, Brazil [email protected]

Nadine Schlueter Division for Cariology, Department of Operative Dentistry and Periodontology Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg Freiburg, Germany [email protected]

XIII Contributors

Falk Schwendicke

Michael Jochen Wicht

Department Operative and Preventive Dentistry Center of Dental Medicine, Charité University Berlin Berlin, Germany [email protected]

Department of Operative Dentistry and Periodontology University Hospital, University of Cologne Cologne, Germany [email protected]

Nicola Scotti

Annette Wiegand

Department of Surgical Sciences Dental School Lingotto, University of Turin Turin, Italy [email protected]

Department of Preventive Dentistry, Periodontology and Cariology University Medical Center, University of Göttingen Göttingen, Germany [email protected]

Carlos Rocha Gomes Torres Department of Restorative Dentistry Institute of Science and Technology of São Jose dos Campos, São Paulo State University – UNESP São Jose dos Campos, São Paulo, Brazil [email protected]

Karen Cristina Kazue Yui Department of Restorative Dentistry Institute of Science and Technology of São Jose dos Campos, São Paulo State University – UNESP São Jose dos Campos, São Paulo, Brazil [email protected]

Pekka Kalevi Vallittu Department of Biomaterials Science Institute of Dentistry, University of Turku Turku, Finland [email protected]

Edoardo Alberto Vergano Department of Cariology and Operative Dentistry Dental School Lingotto, University of Turin Turin, Italy [email protected]

Rayssa Ferreira Zanatta Department of Restorative Dentistry School of Dentistry, University of Taubaté – UNITAU Taubaté, São Paulo, Brazil [email protected]

1

Diagnosis and Treatment Planning Carlos Rocha Gomes Torres, Anna Greta Barbe, Michael Johannes Noack, and Michael Jochen Wicht 1.1

Introduction – 2

1.2

Subjective Exam – 3

1.2.1 1.2.2 1.2.3

 hief Complaint – 3 C Medical History – 4 Dental History – 6

1.3

Objective Exam – 7

1.3.1 1.3.2 1.3.3 1.3.4

 eneral Aspects and Vital Signals – 7 G Extraoral Exam – 7 Intraoral Exam – 7 Esthetic Evaluation – 23

1.4

Evaluation of Caries Risk – 28

1.5

General Treatment Plan – 29

1.6

Planning Restorative Treatment – 31

1.7

Interdisciplinary Aspects – 32

1.8

Oral Health Records – 32 References – 40

© Springer Nature Switzerland AG 2020 C. R. G. Torres (ed.), Modern Operative Dentistry, Textbooks in Contemporary Dentistry, https://doi.org/10.1007/978-3-030-31772-0_1

1

2

1

C. R. G. Torres et al.

Learning Objectives After completion of this chapter, the reader is competent to: 55 Understand the importance of unfolding the patient’s chief complaint 55 Use open-ended questions and periodical summaries as communication tools during the medical interview 55 Apply active listening as a stylistic means to keep patients talking 55 Recognize medical conditions that may interfere with dental treatments 55 Identify indications of antibiotic prophylaxis in risk patients to prevent bacterial endocarditis 55 Identify medicinal product interactions and most prevalent diseases in a patient 55 Describe challenging conditions when treating elderly patients 55 Structure the dental assessment in different sections, i.e., anamnesis, self-reported complaints, extra- and intraoral examination 55 Highlight the most important criteria when assessing caries and non-carious lesions, periodontal and endodontic conditions 55 Differentiate between pathologic and within biological variation conditions 55 Differentiate assessment criteria for different types of restorations 55 Identify biological risks and discriminate harmful from harmless conditions 55 Explain the multifactorial genesis of non-carious lesions and know operative and non-operative treatment options 55 Explain conditions that lead to extrinsic and intrinsic staining 55 Reproduce basic knowledge about occlusion concepts and function in general 55 Understand the basics of dental esthetics 55 Identify risk factors that promote the onset or progression of oral diseases and calculate the individual caries and periodontal risk 55 Come to a patient-centered personalized treatment plan according to shared decision-making concepts 55 Apply ASA classification to categorize patients according their general state of health 55 Differentiate stages within the treatment concept and stick to them 55 Create a patient file and know about the importance of detailed documentation

1.1

Introduction

Diagnosis describes the process of determination and judgment of variations from what is normal [55]. Abnormal situations can bring up discomfort, pain, and loss of function and may compromise esthetics. Therefore, diagnoses of alterations from what is normal in the stomatognathic system is fundamental to execute an efficient dental treatment, aiming the re-establishment of the patient’s health. However, abnormal situations may also be a biological variation and

not harmful to the patient’s health. Based on the most probable diagnosis, a treatment plan can be compiled in close collaboration with the patient [66]. Planning the clinical procedures is crucial since mistakes both in treatment planning and in the practical execution of such plan will lead to a result that is far from the ideal [17, 66]. In modern dentistry, treatment planning should be guided by patients’ wishes and demands in the first place. Based on patients’ chief complaints and findings of the clinical examination, a list of diagnoses is formulated. One by one, the problems are analyzed regarding options for treatment, each one with their inherent advantages and disadvantages. The best solution for each problem is chosen and written in sequence; so, this list of solutions will lead to the treatment plan [66]. The process to reach a treatment plan is primarily driven by dental problems presented by the patient. However, comprehensive evaluation of the patients’ general health, socioeconomic status, and individual preferences is mandatory to reach consent about the most suitable and personalized treatment option. Items included on the treatment plan can be classified by topics, as endodontic, periodontal, restorative, etc. The list is dynamical and can be modified if new problems occur or the patient changes his or her opinion during the course of treatment [66]. The treatment for each individual problem has the objective to reach the idealized final result, in other words, the individually desired oral rehabilitation of the patient. If the proposed treatment for any individual problem conflicts with the proposed general treatment, the individual or general plan has to be modified until it coincides to each other [66]. The patients’ interview should usually begin with the evaluation of the chief complaint and patients’ expectations relative to the treatment outcome. Next, a medical and dental history has to be recorded. On the medical history, the presence of systemic diseases including allergies and medications that affect the patient and more importantly the subsequent dental treatment has to be investigated. On the “dental history,” previous treatments should be evaluated as well as the degree of success that was obtained. Actually, most dental patients are anxious to a certain degree. Agitation is usually observed especially during the first appointment. As dental professionals, we have to know that agitation can lead to speechlessness, and frightened patients tend to forget about what they really want to explain. Therefore, we need to be trained in professional interviewing and how to get to the core of patients’ demands and expectations. The objective part of the evaluation begins with the analysis of the patients’ general aspect followed by the vital signs checking such as blood pressure among others, an extraoral exam of head and neck region, visually or by touch. Then, the dentist follows to the intraoral exam, checking the soft tissue, gingiva, and tooth structure. The goal of the exam is to distinguish the normal from the abnormal, determining which abnormal findings are a problem and require treatment or it

3 Diagnosis and Treatment Planning

will influence the treatment. The nonclinical part of the exam is performed by the analysis of radiographies, plaster models on articulators, and photographs [66]. Nowadays, the clinical approaches should be based on a so-called evidence-based clinical practice, on which the clinician guides their decisions related to the patient’s health on published findings on scientific researches. Therefore, this approach can be defined as the conscious, explicit, and insightful use of the best available scientific evidence when taking decisions about the care of the patients. This vision allows the integration among individual clinical quality of the dentist, the patient’s preferences, and the best basis found on scientific researches [17, 43]. 1.2

Subjective Exam

The data from the so-called subjective exam, also called anamnesis, come from the interview with the patient. It derives from the Greek words, ana (open) and mnesis (memory). In a medical context, anamnesis means recordation, reminiscence, that is, the group of information that is part of the clinical history of the patient up to the moment of the exam [24]. On this exam, crucial information is gathered to determine the patient’s desires and the causal factors of many oral diseases, as well the safety of dental procedures. 1.2.1

Chief Complaint

The chief complaint is the motive why a patient consults the dentist. The answer should be registered on the file, preferably using the exact patient’s wording (. Fig.  1.12). During discussion and registration of the chief complaint, the patient will notice that his problem was acknowledged. Focusing on the chief complaint and paraphrasing it with our own words ensure that patients would feel correctly understood and dentists do not lose sight of the major concerns. Concomitantly it positively affects the doctor-patient relation showing that we listen carefully and really want to get to the core of a patient’s complaint [54, 66]. If the dentist too quickly interrupts the patient or tries to focus on other problems, omitting the discussion of the chief complaints, patients may question the dentist’s professional competencies. The patient should be encouraged and guided to discuss all the aspects of the problems in that matter including location, duration, and quality of symptoms, as well as any related factors. These information are called the history of the present illness. It is advisable to start the interview with an open-ended question that allows the patient to explain their chief complaints. “How may I help you” and “what can I do for you today?” are very nice opening questions since patients desire opportunities to present concerns in their own time [56]. In contrast to closed-ended questions (“I understand you have an aching tooth”), patients will provide sig 

nificantly longer problem presentations when the doctor initiates the interview with an open-ended question. Thereby a patient is respected as an autonomous person rather than a passive, confirmative authority. Patients should not be interrupted when presenting their chief complaint but rather be encouraged to provide as much pertinent information as possible. Active listening is a communication competency that helps health-care professionals to deeply reveal the patients’ concerns, ideas, and explanations about a given disease [38]. In the first step, it is important to present our undivided attention to the patient and encourage them to talk. Nodding and any other open nonverbal communication, including eye contact and an open posture, will help to make the patient feel comfortable and welcome. Telephone calls, ambient noises, or distractions of any other source should be avoided at any time. Just as well, taking notes on a file or in the computer may unsettle the patient while talking. In case there is an urgent need to do so, we should comment on that beforehand and explain to the patient that it is inevitable to take down notes, but we pay full attention notwithstanding. Active listeners avoid interrupting at all costs. After the patient has explained the chief complaint, it is wise to rephrase it with our own words to ensure we have fully understood the central point. We may encourage the patient to correct or add something whenever appropriate. Perception of verbal and nonverbal cueing plays a central role when we try to disclose hidden messages from another person. Signal words like “painful,” “expensive,” “time-­ consuming,” etc. might be a hint for worries a patient does not want to unfold straight away. Observing a person’s body language will help us to get a vision about their mental and emotional state. Addressing a patient’s feelings is the third step that in most cases will lead to a trustful and overt doctor-patient relationship. Potential longer lulls in a conversation may feel awkward for both of the interlocutors. It is not wise to bridge that break immediately nor to pose a second question when the answer is not given immediately. Allowing pauses is a rhetorical device that can inspire a patient to disclose further information. We should always keep in mind that most patients feel tense at least which can cause confusion or short-term oblivion. At the end of medical interview, it is highly recommended to summarize the essential points and ask the patient whether there is anything they would like to address or which has been stated incorrectly. A final summary appears highly professional and marks the end or a new phase within the conversation. In longer consultations, intermediate summaries will help the professional to structure the interview and highlight the most relevant points not only to the patient but also to himself or herself. >> The chief complaint is the motive why a patient consults the dentist. The answer should be registered on the file, preferably using the exact patient’s wording.

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>> It is advisable to start the interview with an open-ended question that allows the patient to explain their chief complaints. “How may I help you? ” and “what can I do for you today?” are very nice opening questions since patients desire opportunities to present concerns in their own time.

>> Before planning an oral examination or dental treatments, the general medical history of the patient has to be checked thoroughly; general health problems or medication may influence therapeutic decisions or the results of dental treatment and may even threaten the patient’s life.

>> Patients should not be interrupted when presenting their chief complaint but rather be encouraged to provide as much pertinent information as possible.

1.2.2.1

>> Perception of verbal and nonverbal cueing plays a central role when we try to disclose hidden messages from another person. >> At the end of medical interview, it is highly recommended to summarize the essential points and ask the patient whether there is anything they would like to address or which has been stated incorrectly.

1.2.2

Medical History

Before planning an oral examination or dental treatments, the general medical history of the patient has to be checked thoroughly; general health problems or medication may influence therapeutic decisions or the results of dental treatment and may even threaten the patient’s life. Also, dentists have the responsibility of guaranteeing that the dental treatments do not produce systemic consequences by interacting with previous diseases or medication intake. Initially, the patient or legal guardian should answer a comprehensive questionnaire concerning the patient’s medical history (. Figs.  1.12 and 1.13), preferably in a quiet environment such as the waiting room. Some dental institutions either send these forms to the patient or offer an online version to be completed prior to the first appointment. During the visit, the dentist will check the answers and address any open question directly with the patient [62]. The form helps to identify conditions that may interfere, complicate, or contraindicate dental procedures [54]. Questionnaires should be modified according to the specialty of the clinician and the category of patient (i.e., elderly, children, etc.), and additional surveys may be added if necessary. Patients or legal guardians should sign the questionnaires. This information needs to be updated on a regular risk-adapted basis [3]. The clinician may identify infectious and contagious diseases of compulsory notification, allergies, current and past medication that may interact with drugs prescribed or injected by the dentist, or systemic diseases (i.e., endocarditis) that may demand preoperative antibiotic treatment [54]. A meticulous record of the medical history should avoid life-­ threatening incidents and identify conditions that require medical consultation. In individuals who present with several systemic diseases and take many medications, the dentist should closely collaborate with a general practitioner to minimize the overall health risk during dental treatment [54].  

 ompulsory Notification of Infectious C Diseases

When reviewing the medical history, the dentist may identify clinical manifestations of infectious and contagious diseases that put the life of a patient at risk or which involve a delay in dental treatment. It may be that the dentist is the first health professional to identify patients with those diseases. Apart from arranging medical consultation followed by medical treatment, the governmental health system has to be notified of some of these cases, following the rules established by each country. Often, the general health practitioner will take care of the procedures, but the dentist should confirm these actions. The disease control system requires certain infectious and contagious diseases to be reported, so that they can trace a map with the number of cases within a specific region and check the risk of an epidemic, enabling initiation of public health measures, such as vaccination to ameliorate the spread of the disease. The list of compulsory notification diseases is frequently revised and changes according to each country. >> When reviewing the medical history, the dentist may identify clinical manifestations of infectious and contagious diseases that put the life of a patient at risk, or which involve a delay in dental treatment.

1.2.2.2

Systemic Diseases

Patients with systemic diseases may require special care, especially those with cardiac disorders. Dental procedures that cause bleeding may allow oral bacteria to penetrate the bloodstream (bacteremia) and establish themselves on abnormal or damaged valves, thus increasing the risk of bacterial endocarditis. According to the guidelines, patients with prosthetic cardiac valves or prosthetic material used for cardiac valve repair, and those with a previous infective endocarditis, are at high risk of bacterial colonization. Other patients, who should receive an antibiotic prophylaxis prior to highly invasive dental procedures [1], include those with congenital heart diseases involving unrepaired cyanotic defects (including palliative shunts and conduits), completely repaired defects with prosthetic material or devices during the first 6 months after the procedure, and repaired defects with residual defects at or adjacent to the site of the prosthetic patch or device. These procedures comprise extractions and periodontal treatments, probing, scraping, gingival surgeries, implants, reimplantation of displaced teeth, and routine dental prophylaxis when bleeding is likely. Patients who have taken a combination of fenfluramine and phentermine, as an appetite suppressor to lose weight, are more susceptible to

5 Diagnosis and Treatment Planning

cardiac valve diseases. Patients that have a joint prosthesis are also at high risk of developing problems associated with bacteria, because they may establish themselves up to 2  years after they have entered the bloodstream [54]. However, in general administration of prophylactic antibiotics cannot be recommended prior to dental procedures to prevent prosthetic joint infection [64], because of the risk of antibiotic resistance; a careful risk-benefit analysis remains necessary. Therefore, antibiotic prophylaxis is not indicated for procedures that present low bacterial incidence, such as dental restoration procedures, placement of a rubber dam, local anesthesia, removal of sutures, radiographies, post cementation, installation of prosthesis, impressions, etc. [54]. Tip

Take your time and try to keep the patient’s medical history comprehensive and up to date. It might save lives.

1.2.2.3

Medications

A patient’s medication may have a broad impact on the stomatognathic system or, in the case of polypharmacy, lead to substance interactions. Certain drugs are known to change the salivary composition or flow rates, increase tissue bleeding, produce lichenoid reactions, lead to gingival hyperplasia, or change the overall appearance of the soft tissues [54, 66]. The reduction in salivary flow is associated with the prescription of over 400 medications, including anticholinergics, adrenaline blockers, antipsychotics, antihistamines, diuretics, and antihypertensives. A reduced salivary flow increases the risk of developing (root) caries, some alterations of the mucosa, an increase in biofilm retention, and reduced quality of life due to xerostomia [10, 54, 65]. Dentists should recognize the use of medications that increase the risk for xerostomia and hyposalivation and should initiate corresponding treatment concepts. Close communication with the general practitioner and the use of alternative medications that have fewer adverse effects on salivary flow may be helpful, accompanied by treatment of the dry mouth symptoms [9]. Tricyclic antidepressants can sensitize patients to epinephrine, a very common vasoconstrictor on local anesthesia. Antiepileptic agents can predispose to gingival hyperplasia in the presence of bacterial biofilm, and antibiotics can reduce the effectiveness of contraceptives [54]. There are restrictions on the use of dental anaesthetic solutions that contains sympathomimetic amine vasoconstrictors (i.e., adrenaline, noradrenaline, levonordefrin, phenylephrine) in patients having hypertension and serious cardiac problems, uncontrolled diabetes mellitus, hypothyroidism, pheochromocytoma, sensitivity to sulfites, use tricyclic antidepressants, phenothiazine compounds or non-selective beta blockers or are crack and cocaine users [4, 54]. Medication for hypertension that contain propranolol, when associated with adrenaline-containing anesthesia, may cause a sudden increase in arterial blood pressure and induce a serious

hypertensive crisis. In such cases, it is recommended to use a non-adrenergic vasoconstrictor such as felypressin. However, its use is contraindicated in pregnant women because it may lead to uterine contractions. The anesthetic substance prilocaine, when used in patients with cardiac arrhythmias who use antiarrhythmic medications such as tocainide, can increase the toxicity of the antiarrhythmic drugs. Prilocaine must not be used in patients with anemia or pregnant women because of the risk of methemoglobinemia [4]. Retraction cords with adrenaline used as vasoconstrictors have been abandoned due to the availability of better alternatives for hemostasis [54]. In addition, use of epinephrine in patients with antidepressants needs to be analyzed with caution due to its potential for interactions [54]. When oral hypoglycemic drugs are swallowed and absorbed, they are released into the bloodstream. Some molecules are free in the blood and produce its therapeutic effects, while the rest are bound to plasma proteins. However, nonsteroidal anti-­ inflammatories can compete with oral hypoglycemic drugs for these plasmatic bonds, increasing the fraction of free molecules, which may result in hypoglycemia. 1.2.2.4

Allergies

The patient’s reports regarding allergy history and anamnestic allergic reactions must be investigated, especially with regard to previously injected anesthesia. It is well-known that many problems related to anesthesia occur because of accidental intravascular injection, high dosages, and excessive use of anesthetic. Some individuals present allergic reactions, especially to the preservatives of the injected solution. Naturally, patients that report allergy problems with local anesthesia should not receive this type of medication until further investigation has been performed by a specialized doctor. The patient’s opinion should always be trusted until those additional tests have excluded the risk of allergy. This ­precaution is necessary, considering that anaphylactic shock can put the patient’s life at risk, requiring immediate treatment with basic life support measurements and necessitating removal to a hospital [54]. >> Some individuals present allergic reactions, especially to the preservatives of the injected solution.

Some patients report latex allergies; in those cases, it is recommended that the clinician uses vinyl gloves and a rubber dam without latex. Other allergies with relevance to dental treatments include allergic reaction to restorative materials, such as amalgams or resinous monomers, and will dictate the choice of dental materials to be used. Some individuals also present allergy to hydrogen peroxide, which contraindicates bleaching treatments, especially those techniques that are available at home. 1.2.2.5

Older Patients

Because of the well-known demographic changes, particularly in western countries, the number of older patients that need to be treated in dental practice will continue to increase over the coming decades. These patients represent a

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vulnerable and heterogeneous patient group, due to a great number of changes related to aging, behavior, diet, and oral and systemic health; accordingly, this group requires special attention. The prevalence of multimorbidity and polypharmacy is high and has a negative impact on daily oral hygiene capabilities. Neurodegenerative or mental disorders such as depression, Alzheimer’s disease, and Parkinson’s diseases play a major role in reduced oral health [8]. Furthermore, around 50% of individuals over the age of 75  years take at least two medications [12, 54], increasing the risk of reduced salivary flow rates and oral diseases [9]. >> Because of the well-known demographic changes, particularly in western countries, the number of older patients that need to be treated in dental practice will continue to increase over the coming decades. >> Around 50% of individuals over the age of 75 years take at least two medications, increasing the risk of reduced salivary flow rates and oral diseases.

The aging process in older patients produces physiological changes that are not pathological. Attrition, erosion, and abrasion of enamel reduce its thickness so that it becomes more mineralized and translucent; the underlying dentin becomes more apparent, resulting in a yellow appearance of the teeth, and the pulpal chamber reduces in size. The chromogenic substances from the diet penetrate the enamel’s microcrystalline structure, making it darker. The gum may become inflamed and friable, associated with gum recession and consequent exposure of the root. The oral alterations associated with malnourishment, immunosuppression, dehydration, smoking, alcohol consumption, diseases, medications, and dental problems reduce the ability to feel the taste and smell in older patients [54]. The perception of salt and bitterness and the olfactory senses lower with age, while the perception of sweet and sour is unchanged. As a result, food becomes less tasty and unappetizing. Therefore, sugar, fat, and salt are added in an attempt to improve the taste. It is crucial to evaluate dietary habits in older patients to identify malnutrition, give suggestions for improvement while lowering the risk for dental diseases at the same time. For example, aromatic herbs can improve the taste of food in place of sugar and salt. Saliva stimulants, candy, sugar-free gum with citrus aromas that contain xylitol or other sugar substituents, and brushing or scraping the tongue can improve the sense of taste, while smoking cessation can improve the olfactory perception of older people. Periodontal diseases can progress faster in older patients, and root caries is the most significant reason for dental loss in these patients. Inefficient removal of the biofilm, reduced salivary flow rates, a diet rich in refined sugar, the presence of fixed or removable prosthetic appliances, abrasion of the cementoenamel junction (CEJ), gingival recession, and bone loss due to periodontal disease mean that the root surface is more prone to caries. Accordingly, dental restorations are hard to perform, satisfactory filing materials are missing, and the restorations are at a high risk of caries recurrence [54].

1.2.2.6

Psychological and Social Aspects

During anamnesis, the clinician should analyze the patient’s expectation and priorities relative to the treatment and his oral health in general. Knowing about a patient’s priority is crucial when it comes to treatment decisions. Patient’s expectations are highly variable and in the vast majority of cases not congruent with those of the attending dentist. Accepting that patients have different views than ours leaves the decision-­making process much easier and both doctors and patients much more satisfied. Therefore, we have to evaluate what is important for an individual patient. Esthetics, comfort, time-consumption, monetary aspects, longevity, success rate, and biocompatibility are among the most important categories that should be discussed before we start discussing treatment options. Social inequality in many countries leads to diminished access and lower financial means for medical treatment of the socially deprived. Caries, however, the most prevalent chronic disease worldwide most often affects underprivileged members of our society [59]. In order to overcome this obvious inconsistency, health-care systems should become aware of this immanent problem and try to make dental health services accessible and affordable for those who are in need of it. Overtreatment of people in higher socioeconomic positions reflects the flip side of modern health-care systems. >> Social inequality in many countries leads to diminished access and lower financial means for medical treatment of the socially deprived.

1.2.3

Dental History

The patients’ dental history comprises the registration of previous experiences in terms of dental treatments as well the current oral problems (chief complaint). Those reports give us valuable information about previous and existing problems, positive and negative experiences with the dental treatment, how often a patient visited the dentist, and the patients’ attitude toward past dental treatments. Integration of the information will give us an overall view of a patient’s attitude and level of significance about his oral health status. The patient can report problems with specific types of dental procedures, which may be modified, if possible, to allow more comfort [54, 66]. The patient may not spontaneously give the information that we might need, and it is necessary that the clinician directs the interrogatory, asking some specific questions in relation to (thermal) sensitivity or discomfort during chewing, if he presents some type of pain; if he has had any trauma on the face, infections, lost or fracture of restorations, tooth fractures, and impaction of food in between the teeth; and if he presents difficulties during the hygiene or bleeding when doing the oral hygiene. It should also be asked whether a patient uses dental floss, and how often, asking information about the areas that he cannot pass the dental floss or if the

7 Diagnosis and Treatment Planning

dental floss rips when passing between the teeth. Additionally, it should be asked whether the patient is satisfied with the oral esthetic, the shape and color of their teeth, or any other aspect that he or she may want to point out. In case there is a report of any problem, complementary exams are used to get to a specific diagnosis [54, 66]. One example of a questionnaire about the dental history can be seen in . Fig. 1.13 and may be answered by the patient alongside with the medical history questionnaire.  

mobility, and it can indicate the presence of infections or neoplasia. Muscles should be palpated, searching for rigid or sensitive areas. The mastication muscles can present trigger points that may be related to temporomandibular disorders. The region of the temporomandibular joint (TMJ) should be palpated, asking the patient to open and close the mouth, to verify the presence of pain, clicks, or crepitation. 1.3.3

Tip

The more patient-related information you get, the more reliable your diagnosis will be.

Intraoral Exam

During the intraoral clinical exam teeth, soft tissues and periodontal structures are examined. 1.3.3.1

1.3

Objective Exam

After anamnesis and subjective examination, a clinician conducts the objective clinical examination. Records obtained from the subjective exam can help to guide the clinical exam, allowing that the most probable diagnosis is reached [54]. The clinical exam consists of the general evaluation of the patient, outside and inside the mouth, and the esthetic analysis. From the reports of the subjective exams and the changes found on the objective exam, the clinician will elaborate a problem list that needs to be addressed for a complete rehabilitation of the patient. 1.3.1

General Aspects and Vital Signals

As soon as the patient enters the office, his general appearance may be observed. He may present as a healthy rather unremarkable person or present signs of debility, malnutrition, malformation, or signals that suggest a congenital syndrome. Deficiency on the general self-care, as the lack of personal hygiene, can be associated with the lack of compromise on the maintenance of the oral health. Vital parameters, such as blood pressure and heart rate, may easily be checked during the first or any follow-up appointment. Instant blood sugar analysis can indicate the presence of diabetes. Patients presenting signals or symptoms of systemic problems should be referred to a general practitioner prior to dental treatment, except in case of an emergency.

Evaluation of the Soft Tissues

A visual and/or tactile analysis is performed on the cheeks, lips, palate, dorsum, and, under the tongue, the vestibule regions, and the tonsils. The presence of ulcer lesions or nodes, vesicles, or inflammation has to be thoroughly investigated. In some cases, the dentist is the first to detect infectious and contagious diseases, as well as neoplasia, that can put the patient’s life at risk. Many infectious diseases present their first signals inside the oral cavity. Every clinician should be prepared to diagnose or at least suspect any alterations and direct the patient to a specialized dentist or doctor for further analysis [54]. 1.3.3.2

Periodontal Evaluation

A thorough periodontal evaluation is essential for all patients, not only to determine the periodontal situation and its effects on possible dental restorative treatment plans but also to establish the potential effect of existing or planned restorations on periodontal health [66]. Also, it is well-known that many diseases such as diabetes have an impact on periodontitis and should therefore be treated. Visually, a healthy gum is pink and firm, with the attached gingiva presenting the aspect of an orange peel; in contrast, inflamed gum is usually red, soft, swollen, and smooth. The depth of the gingival sulcus must be verified with a probe. In healthy gums, no bleeding should occur after probing, and the gingival sulcus should be 1–2 mm deep. The presence of calculus and periodontal pockets with a sulcus deeper than 3 mm, as is the case with inflammatory active pockets associated with bleeding, is an indicator of periodontal disease [54]. The periodontal chart is a schematic representation of the depth of the periodontal pockets and should be filled out correctly to determine the necessity for periodontal treatment (. Fig. 1.15). The calculation for the gingival bleeding index should be executed and registered on a clinical chart. Surfaces that present bleeding are registered, and their percentage in relation to the total surfaces that were analyzed is calculated. The involvement of bifurcations on the posterior teeth is evaluated, mobility of teeth as a result of bone loss or excessive occlusal forces; these factors should be taken into account when performing risk assessment for each tooth and when making therapeutic decisions [54].  

1.3.2

Extraoral Exam

Before any intraoral examination, the head and neck region should be checked first. The exam comprises visual assessment and palpation. Visual aspects can show us sores, asymmetries, swollen areas, redness, or fistulas. The palpation of the submandibular and cervical lymphatic glands can show swelling of lymph nodes, sore or not, hard or with

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>> A thorough periodontal evaluation is essential for all patients, not only to determine the periodontal situation and its effects on possible dental restorative treatment plans but also to establish the potential effect of existing or planned restorations on periodontal health.

A radiographic exam may be indicated to analyze bone topography. Then the presence of gingival recession areas and regions with a small quantity or lack of attached gum is evaluated, which is registered on the clinical chart. Presence of biofilm and residues indicates deficiency of oral self-care. The existence of gingival inflammation impairs dental restorative procedures, because of the difficulty in obtaining a dry field, risking the success of the treatment; the disease needs to be controlled and the situation improved before planning further treatments [54]. The presence of dental restorations with an inadequate contour can result in periodontal problems. Overcontouring and the resulting overhangs in the proximal area, due to an excess of restorative material that pours out during application, result in inflammation and pain during cleaning by the patient (. Fig. 1.5b). Open approximal contacts, particularly in the posterior region, foster food impaction and increase biofilm accumulation. These conditions may lead to gingival inflammation, tooth dislocation, increased mobility and bone loss [54]. In cases of deep caries lesions or necessary restorative treatment, radiography should be used to estimate the position of the cavity margin, to assess whether there will be an invasion of the biological width [66]. Teeth that need restorative treatment, but have a doubtful periodontal prognosis, should be noted on the clinical chart and added to the problem list. Until the diagnosis of this particular tooth becomes positive, the restorative treatment should be as minimal as possible, and the treatment plan has to remain flexible [66].  

1.3.3.3

Dentition Evaluation

The dentition is subject to a broad range of alterations, which can lead to loss of structure, pain, or pulpal symptoms. Others are related to the formation of dental structures, such as amelogenesis and dentinogenesis, the position of a tooth in the jaw or agenesis. In general, the visual exam should be performed after air-drying the teeth and under good lightening conditions. Additional isolation of the area during examination can be achieved with cotton rolls and saliva ejectors. However, cotton rolls may hinder the view on the soft tissues. All teeth should be clean, without residues of bacterial biofilm and extrinsic stains, which might require a previous prophylaxis. Unwaxed dental floss may be passed through all approximal contact areas. In case the floss rips or tears apart, it indicates a rough surface, excess restorative material, or cavities. Tip

Meticulous examination of periodontal conditions is as fundamental as assessment of the teeth.

Detection of Caries Lesions Caries lesions are clinical symptoms of the disease “caries,” resulting from the unbalance of demineralization and remineralization processes. Early stages impose as subsurface lesions in the enamel, eventually progressing toward the dentinoenamel junction (DEJ) and later on into the dentine. Surface cavitation occurs at a rather late stage as a result of mechanical instability. Caries lesions usually progress very slowly in enamel and take up speed past the DEJ.  Detection and diagnosis of caries lesions are a challenging process. On the occlusal site, a seemingly intact surface can overlay a rather extensive lesion, a phenomenon that is referred to as “hidden caries.” Examination of interproximal sites is challenging as well, because we do not have a direct view on the surface. Meticulous cleaning and air-drying prior to visual examination and utilization of a validated caries classification are reported to be sufficient and accurate [26]. However, bitewing radiographs are extensively used as an adjunct caries detection method. Bitewing radiographs are highly accurate for cavitated proximal lesions and suitable to detect dentinal caries lesions [61]. Although repeated bitewing radiographs may result in overdiagnosis and hence overtreatment, radiographs are a suitable method for monitoring interproximal non-cavitated lesions that are treated non-­operatively or microinvasively. On root surfaces, especially in patients with periodontal pockets, lesions can progress fast, affecting the pulp tissue. Detection of such lesions may be complicated by the presence of the gingival tissue, and here radiography plays a very important role, too. Progression of a caries lesion depends on many variables, for which many detection methods are available. For detailed information, see 7 Chap. 3.  

>> Bitewing radiographs are highly accurate for detection of cavitated proximal lesions. They are also a suitable method for monitoring interproximal non-cavitated lesions that are treated non-operatively or microinvasively.

Non-carious Lesions Non-carious lesions result from the loss of dental structure without the participation of bacterial biofilm. They can be divided accordingly to its etiology in erosion, abrasion, abfraction, and attrition, even though in many cases the origin is multifactorial. The term dental erosion is used to describe the physical result of a pathologic, chronic localized, and usually painless loss of hard tissues that is chemically attacked by acids without the involvement of bacteria [7]. The acids attacking enamel and later on dentin may be of extrinsic (diet) or intrinsic (reflux) origin. The acids promote loss of structure and softening of the surface layer, which is then worn by the friction of the food bolus or brushing, characterizing the erosive tooth wear (ETW). According to the etiology, the lesions can be classified as extrinsic, intrinsic, or idiopathic

9 Diagnosis and Treatment Planning

(unknown origin). As an example of extrinsic acidic sources, the frequent consumption of sour fruits, low-pH juices or sodas, sports drinks, and alcoholic beverages is to be mentioned. Other sources are the work environment (as industrial acids), pool water, and some medication as effervescent tablets of vitamin C (. Fig. 1.1a) may be the cause for dental erosion. The main characteristic of ETW is the loss of contour and natural surface morphology. On occlusal surfaces, the flattening of the structures and cupping of the cusps are  

typical signs. In advanced situations, the morphology may completely transform into concave surfaces. Restorations are not affected and become exposed (. Fig. 1.1b). On smooth surfaces, typical characteristics are surface flattening and an intact rim of enamel along the gingival margin. Concavities usually wider than deep can be observed in some cases [33].  

>> Non-carious lesions result from the loss of dental structure without the participation of bacterial biofilm.

a

b

c

d

e

f

..      Fig. 1.1  Non-carious lesions. a Dental erosion caused by the very frequent ingestion of lemonade; b erosion resulting from the abusive ingestion of cola based soda; c erosion on the tip of the cusps on patients with gastroesophageal reflux associated with attrition;

d erosion of the lingual surfaces because of regurgitation of gastric acid; e abrasion by excessive brushing; f, g abfraction on anterior and posterior teeth; h, i intense attrition in patient with bruxism

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g

h

i

..      Fig. 1.1 (continued)

As example of the intrinsic source, gastric acids produce an erosive challenge during vomiting, constant regurgitation, or reflux. The gastric acid has a pH of 1–1.5 and hence is much lower than the critical pH for enamel dissolution. Intrinsic erosive challenges are associated with psychosomatic disorders or psychogenic eating disorders, such as nervous anorexia or bulimia. Somatic causes comprise pregnancy, alcoholism, treatment for alcoholism and gastrointestinal dysfunction, hiatus hernia, peptic and duodenal ulcers, and gastroesophageal reflux. Dental erosion due to chronicle regurgitation often hits the internal region of the arches, corresponding to the track of the regurgitated acid over the dorsum of the tongue, along the palatal surfaces of the maxillary teeth and the occlusal sites of the posterior mandibular teeth (. Fig. 1.1c, d) [7]. Even though it may affect the occlusal and lingual surfaces of every maxillary tooth, it is confined to the buccal and occlusal sites of the mandibular premolars and molars. Buccal surfaces of maxillary teeth are usually not affected, and the posterior teeth are protected by the neutralizing saliva from the parotid gland. Lingual surfaces of the mandibular teeth are covered by the tongue and thereby protected from the acidic challenge [7]. Eliminating or reducing the causative factor, i.e., the source of acid, is crucial for patients with erosive problems. This can include medical treatment for any intrinsic prob 

lem. Some studies suggested that those patients should not brush their teeth immediately after acid exposure, although others did not confirm this recommendation. The toothbrush should have extra soft bristles, and the toothpaste should contain little abrasive substances. Additionally, fluoride-­containing mouth rinses may be used on a regular basis. A neutral 2% sodium fluoride gel or 5% fluoride varnish can be applied on dental visits. The use of sugar-free chewing gums can stimulate salivary flow. Deeply eroded lesions might benefit from a mechanical barrier against acid attacks by adhesive restorations [46]. Dentin sealants also seem to be rather resistant against erosive conditions and might serve as an intermediary treatment option for exposed dentin surfaces [6]. Acidic drinks should not be held in the mouth, especially not being “swished” around the teeth. Using a non-plastic straw will minimize the fluids’ contact time with the teeth and save our environment at the same time. >> Eliminating or reducing the causative factor, i.e., the source of acid, is crucial for patients with erosive problems.

Abrasion is defined as tooth wear induced by substances or objects other than food. Tooth brushing is the main etiological factor of abrasion depending on tools, dentifrices, and

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11 Diagnosis and Treatment Planning

techniques used for the cleaning procedure (. Fig. 1.1e). In addition, the type of material, hardness of the bristles, whether these bristle tips are rounded or not, and their flexibility have an impact on abrasive wear, as well as abrasivity, pH, and the quantity of toothpaste used [28]. Abfraction derives from the Latin word frangere which means to break. It is used to describe the specific wedge-­ shaped defects in the cervical region, resulting from occlusal forces applied to the tooth, leading to its flexion (. Fig. 1.1f g, g). Parafunctional forces especially during lateral movements of the mandible expose teeth to intense flexion and shear forces, resulting in substance loss in the cervical region, which is the weakest part of the tooth. Lesions are located on the CEJ, caused by microfractures on the enamel, growing perpendicularly to the long axis of the affected tooth. The resulting damages have the wedge shape and sharp edges [7]. The incisal/occlusal wall generally has sharp cavosurface angles, forming a right angle to the external tooth surface. The gingival cavosurface angle are located on the root surface [33]. Apart from dynamic occlusion parameters, the use of hard toothbrushes and a horizontal brushing technique are frequently associated with the occurrence of non-carious cervical lesions [30]. Differential diagnosis and origin of non-carious cervical lesions is not always unequivocal. There is a high chance that a lesion’s etiology has more than one origin; however, some fundamental properties can be observed. Abrasive lesions are more frequently on the buccal surfaces and above the gum, while abfractions can be located partially or completely under the gum. The abrasive lesion is characterized by a rather shallow and rounded morphology, whereas abfractions have a wedge shape with sharp edges. Abrasions usually involve many neighboring teeth, while the abfraction can occur in just a single tooth. Abfraction is always associated to some occlusal interference, while the abrasion is not necessarily accompanied by an occlusal interference. As abrasion intensifies structural loss of a tooth under erosive conditions. Erosion and abrasion may be important secondary factors on the progression of lesions induced by the abfraction. It is important to control the etiological factors of non-carious cervical lesions, because restorations will be subjected to the same factors that initially caused the lesion [7].  

 

>> Differential diagnosis and origin of non-carious cervical lesions is not always unequivocal.

Depending on the size, location, and presence of sensitivity, treatment of non-carious (cervical) lesions particularly consists of controlling the etiological factors. Additionally, this causal therapy can be flanked by the use of desensitizers or ultimately the restorations of these lesions. The restorations should be placed when the lesion is active, and non-­operative treatment is not capable to arrest the lesion. A restoration can be advantageous when the structural tooth integrity is compromised, there is a risk of pulp exposure, or the defect is

esthetically unacceptable for the patient. Further indications for restorations may be remaining dentin sensitivity after non-­operative care, periodontal problems, the use of the tooth as an abutment for prosthesis or due to caries lesions [7, 54]. Restorative procedures in the cervical part of a tooth are demanding, since moisture control and contouring might be challenging. The indication should thoroughly be weighed against potential disadvantages, especially for periodontal health. Attrition is defined as wear by tooth-to-tooth contact without the impact of any other substance. It can result from physiological or pathological etiological factors. Physiological wear is considered a slow degradation of the dental shape, manifested as a flattening of the tips of the cusps in posterior teeth and the incisal curve of the anterior teeth (. Fig. 3.16c, d) [66, 70]. Characteristic features are opposing wear facets with sharp margins. When the wearing becomes excessive, it may be related to pathological causes. Excessive attrition is primarily caused by bruxism that will result in facets on the opposing teeth (. Fig. 1.1h, i). Since elimination of the parafunctional habits is very hard to achieve, occlusal acrylic resin splints are used to prevent the patient from further tooth wear. The clinician has to identify patients with excessive tooth wear, especially younger individuals. Significant attrition areas that resulted on exposition of dentin and present sensibility or discomfort might be considered for restorative treatment. However, a previous analysis of the occlusion and the causal factors of the wearing should be carried out previously [54]. The resulting wear of an antagonistic tooth against a restoration very much depends on the restorative material used. Wear analysis showed that amalgam would cause a slightly increased wear to the opponent tooth [66]. Microfilled composites result in wear similar to the enamel, while hybrid composites generate a slightly increased wear compared to enamel. The microhybrid and nanofilled composites seem to induce a similar wear than the enamel. Cast gold restorations are usually softer than enamel and amalgam, resulting in less wear of the antagonistic tooth. Feldspar ceramics produce extensive antagonistic tooth wear; however, modern dental ceramics are significantly less abrasive [66]. It is not rare to have patients complaining of sensibility on the root surface, characterized by an acute pain, generally associated with a gingival recession and exposition of the cementum or dentin. The most accepted theory to explain this phenomenon is called the hydrodynamic theory, claiming that pain results from the movement of fluids inside the dentinal tubules, stimulating the mechanical receptors within the pulp tissue [14]. Fluid movements may be initiated by thermal changes, air-drying, osmotic pressure, or mechanical contact. Any treatment that reduces this movement of fluids closing the tubules partially or completely can help to reduce the sensitivity [50]. Further details relative to dentine sensitivity can be obtained in 7 Chap. 18.  

 

 

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Tip

The clinical management of non-carious cervical lesions should always include elimination or reduction of the causative factors rather than just restoring the defect.

Pulpal Diseases Unhindered progression of a caries lesion may lead to pulpal symptoms which manifest as pain and at a later stage can turn into pulpal inflammation and necrosis. Patients with pulpal diseases consult the dentist because they suffer from pain. Non-symptomatic necrosis of the pulp is frequently overseen or incidentally detected on a radiograph. Partial removal of the pulp (pulpotomy) can be a sufficient therapy for reversible forms of pulpitis or exposure of the pulp during caries excavation. Irreversible pulpal inflammation and pulpal necrosis however require endodontic ­ treatment of the entire root canal system. Pulpal diagnosis is primarily based on reported symptoms, the reaction to thermal and percussion tests and ultimately radiographic examination. Conducting pulp sensitivity testing on each tooth is not recommended. However, teeth with a symptomatic history, questionable periapical radiographic findings, or those considered for restoration might be tested for signs of pulpal vitality. It is embarrassing for both clinician and patient to discover that a recently restored tooth had a necrotic pulp before the treatment and becomes symptomatic after it [66]. A more detailed description about diagnosis of the pulpal alterations can be found in 7 Chap. 9.  

Dental Integrity and Fractures When submitted to occlusal load, dental cusps tend to undergo deflection, which is strongly increased when a restoration is present. The greater the amount of substance loss, the bigger the cuspal deflection will be. The quantity of movement depends on the intensity of the force acting on the tooth. The force is determined by the muscular strength of the individual and correlates with parafunctional activities such as bruxism, clenching, and grinding. Under the influence of repetitive loads, cusps suffer fatigue and may happen to fracture, losing that portion of the dental structure. Cracking of a tooth as a result of mechanical overload oftentimes cannot be visually detected, originating a painful process called “cracked tooth syndrome” [42]. When cracked teeth are submitted to masticatory or occlusal loads, the crack line opens, resulting in movement of the dentinal fluid. According to hydrodynamic theory, this movement can cause pain. Patients generally report acute and sharp pain, upon loading and unloading forces, usually when chewing hard or

granulated food. The patient is usually capable to localize the cracked tooth. Cracked teeth mostly respond to vitality tests and can present sensitivity when eating cold, hot, sweet, or acidic food. Usually no alterations can be seen radiographically; teeth are either clinically intact or restored. Diagnosis is performed with a device that allows placing pressure on each cusp separately or by removing the restoration and inspecting the cavity wall. Dye can be applied into the cavity in attempt to visualize a potential crack. For more details about the cracked tooth syndrome, see 7 Chap. 18.  

>> Cracking of a tooth as a result of mechanical overload oftentimes cannot be visually detected, originating a painful process called “cracked tooth syndrome.”

Complete tooth fractures can be due to trauma or progression of a crack. It should be verified which tissues are involved, as the fractures may be having affected the enamel, enamel/dentin, enamel/dentin/pulp, or enamel/dentin/pulp/ periodontal tissues. Fractures that involve only the enamel or the enamel and the dentin can usually be treated with restorations. Fractures involving the pulp may need an appropriate endodontic treatment. Preserving vitality of the pulpal tissue is preferred whenever feasible and particularly in cases with incomplete root formation. Fractures involving periodontal structures, including infrabony defects, may need surgical crown lengthening or an orthodontic extrusion therapy prior to restoration. Root fractures may occur as a side effect of endodontic treatment or due to trauma. Detection and treatment of such fractures is challenging, and these cases are often called hopeless. Multidisciplinary approaches in terms of combined orthodontic, surgical, and restorative treatment can lead to complete rehabilitation of complicated crown-root fractures. . Figure  1.2a–d shows examples of cracks and fractures in anterior and posterior teeth. For details, see 7 Chap. 14.  

 

Shape and Position Abnormalities Teeth can present deviations in shape or size. Such alterations can have genetic origins, such as conical teeth, dens in dente, and microdontia or can be related to infectious diseases during odontogenesis period, such as congenital syphilis that results in in screwdriver-shaped incisors (Hutchinson incisor) or mulberry molars. Disproportion between tooth size and size of the jaw can result in crowding or dental gaps called diastema. Gaps are usually closed with orthodontic procedures. In some cases, remaining gaps particularly in the anterior region can be corrected with direct or indirect restorations. Transposition or ectopic eruption describes the phenomenon when teeth do not erupt at their predetermined position within the jaw. Missing teeth may occur due to agenesis or avulsion, bearing the potential risk of adjacent tooth migration (. Fig. 1.3a–i).  

13 Diagnosis and Treatment Planning

a

b

c

d

..      Fig. 1.2  Dental fractures. a, b Cracks and fractures on the anterior teeth; c, d cracks and fractures on posterior teeth

a

b

c

d

..      Fig. 1.3  Abnormalities on the shape and position. a Diastemas between anterior teeth; b cone-shaped right lateral maxillary incisor; c transposition of the maxillary canine on the place of the right lateral

incisor; d, e dens in dente; f anodonty of the lateral incisors; g left maxillary canine positioned in place of the lateral incisor; h hypoplasia of the enamel on the incisal third of the anterior teeth; i imperfect amelogenesis

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e

f

g

h

i

..      Fig. 1.3 (continued)

Color Changes Most patients are unsatisfied with their tooth color and feel esthetically impaired. Consequently, the desire for tooth whitening is among the most often heard demands when assessing the patients’ chief complaints. Color changes can be of extrinsic or intrinsic origin. Extrinsic staining is frequently caused by food and beverages, where chromogenic agents attach to

the enamel surface. For example, staining can be observed after regular coffee or tea consumption and tobacco smoking, due to ingestion of iron-containing vitamin compounds or from chromogenic bacteria in the biofilm (. Fig. 1.4a). Some substances capable to cause extrinsic discoloration can also penetrate to some extent into the tooth, resulting in a mostly yellowish appearance. Intrinsic staining occurs when chro 

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15 Diagnosis and Treatment Planning

mophores are incorporated into the hard tissues during tooth development or caused by conditions acquired later in life, such as endodontic treatment, dental trauma, or caries. In most cases application of an oxidant bleaching agent is the therapy of choice, like hydrogen peroxide or carbamide peroxide, diffusing into the enamel and dentin and breaking the chromophores, leaving the tooth with a significantly lighter appearance. Tooth whitening can be performed at the dental office or at home, in a single visit or over a longer period. Peroxide concentrations vary considerably among products and are strictly limited in several countries.

In cases where tooth whitening is not sufficient to fulfill the patients’ need, veneers may be an option to enhance the anterior teeth esthetics, a procedure described in 7 Chap. 17.  

>> Most patients are unsatisfied with their tooth color and feel esthetically impaired. Consequently, the desire for tooth whitening is among the most often heard demands when assessing the patients’ chief complaints.

Some people have naturally darker teeth than others do. Intrinsic color changes can be caused by problems during tooth formation. Excess of fluoride intake can result in hypo-

a

b

c

d

e

f

..      Fig. 1.4  Color changes of tooth structure. a Extrinsic staining due to smoking; b dental fluorosis; c, d amelogenesis imperfecta; e staining due to ingestion of tetracycline; f hypomineralization on enamel due

to trauma and intrusion of the deciduous teeth; g, h darkening of tooth 22 by pulp calcification after the orthodontic traction. i Darkening of the tooth 11 due to pulpal necrosis after trauma at the region

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..      Fig. 1.4 (continued)

g

h

i

mineralization during enamel formation, resulting in whitish areas of enamel, up to a surface with porosities or pits in the more severe situations (. Fig.  1.4b). This side effect of a chronic fluoride overdose during tooth formation is called dental fluorosis. Different in origin, amelogenesis and dentinogenesis imperfecta result in great esthetic problems, which may require extensive operative care (. Fig.  1.4c,  d). When ingested during odontogenesis, tetracycline, an antibiotic widely used in the past, deposits itself inside the dental structure and results in horizontal striped pattern (. Fig. 1.4e).  

 

It should be noted that in cases where dental bleaching is included in the treatment plan, it should precede any restorative procedure on anterior teeth. A washout phase of minimum 2 weeks should be observed after the bleaching, to allow the color stabilization and peroxide release from inside the tooth structure. Besides, the patient should be informed that restorations and existing prosthetic appliances will not be bleached and probably need to be replaced afterward. Tip

 

>> Excess of fluoride intake can result in hypomineralization during enamel formation, resulting in whitish areas of enamel up to a surface with porosities or pits in the more severe situations.

Trauma or infection in deciduous teeth can result in hypomineralization or hypoplasia in the following permanent teeth (. Fig.  1.4f). Trauma or orthodontic movements can result in dystrophic calcification of the pulpal tissue, also promoting dental darkening (. Fig.  1.4g, h). In other cases, trauma can lead to pulpal necrosis, which decomposition products darken the crown (. Fig. 1.4i). As mentioned above, aging as a natural process results in darkening of teeth because of a higher degree of dentin mineralization and the enamel becoming thinner and more translucent at the same time.  

 

 

Most patients are dissatisfied with their tooth color. Therefore, whitening procedures should be part of the portfolio of modern dentists.

Analysis of Existing Restorations The decision whether to keep or to replace an existing restoration is a demanding process in everyday routine. Overtreatment, in terms of random or premature replacement of an existing restoration, would invariably result in an unnecessary removal of the tooth structure, including the risk of accidental pulp exposure. Re-dentistry, i.e., replacement of restorations, is reported to be the dentist main duty [47]. The diagnostic process and decision tree in favor or against restoration replacement should be primarily based on

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health risks for the patient and always be a result of a shared decision-­making process [37]. From an ethical point of view, it is inacceptable that clinicians take decisions for their patients and even worse without providing any justification. Therefore, transparent findings and diagnoses as well as patients’ preferences should be the basis in the decision-making this process. >> The decision whether to keep or to renew an existing restoration is a demanding process in everyday routine. Overtreatment in terms of random or premature replacement of an existing restoration would invariably result in an unnecessary removal of the tooth structure, including the risk of accidental pulp exposure. >> Transparent findings and diagnoses as well as patients’ preferences should be the basis in the decision-making this process.

Clinical assessment of restorations should be carried out under dry and well-illuminated conditions, isolated with cotton rolls and saliva ejectors. The clinician first may visually inspect the restoration, followed by a tactile examination with an exploratory probe and probably the use of dental floss. Bitewing radiographs can yield additional information in particular areas that cannot be assessed clinically. For evaluation of amalgam restorations, many conditions should be observed, such as transparency through the enamel, marginal integrity, fracture lines, improper anatomic shape (overcontour, undercontour, proximal overhangs, inappropriate height of the marginal ridge relative to the adjacent tooth, and inadequate interproximal contacts), recurrent caries, inadequate occlusal contact, undesirable surface roughness, and violation of the biological width [54, 66]. Facial walls of proximal boxes of the Class II preparations happen to be very thin in many cases and not supported by dentin. Due to enamel translucency, shining through ­amalgam restorations may impair the esthetics. However, this does not necessarily indicate that the restoration needs to be replaced, unless it is among the patient’s chief complaint (. Fig. 1.5a) [54]. When there is no apparent marginal degradation, the discoloration appears gray or blueish. However, when the discolored area is yellow or brownish, and it seems to have communication with the cavosurface margin, presence of a caries lesion in the interface is likely, indicating a health risk for the patient. Consequently, replacement of this restoration should be discussed with the patient [66]. Proximal overhangs, because of inadequate use of the matrix and wedge system during restoration, create conditions favorable for biofilm adhesion and niches that are difficult to access during oral hygiene (. Fig. 1.5b). Diagnosis of such overhangs is usually performed with radiographs and the use of an exploratory probe or dental floss. The clinician can try to remove the excess of restorative material with a steel abrasive strip or with an oscillating diamond-coated file (EVA system) in a handpiece (. Fig. 4.36). However, in most cases, replacement of the restoration may be necessary.  

 

 

The margins of the restorations may be examined with an exploratory probe, moved perpendicularly to the interface tooth restoration. It should be moved from the restoration toward the dental surface and the other way round, working along the whole margin [70]. In case the explorer gets stuck from the tooth toward the restoration, there is an excess of restorative material, which can be removed by finishing and polishing (. Fig. 1.5c). In case it gets stuck from the restoration toward the tooth, there is a lack of material. It should be evaluated whether these margins are accessible to oral hygiene and whether dentin is exposed. The latter may be an unfavorable condition and be considered for either repair or replacement of the restoration. When the probe gets stuck both ways, there is a ditch on the interface [66]. Marginal ditching is a result of wear or fractures, either in amalgam or in the enamel, mostly due to improper cavity preparation (. Fig. 1.5d, e). The presence of marginal ditching does not necessarily implicate the presence or an increased risk for developing a caries lesion [35]. Corrosion products of amalgam may seal the interface and keep the restoration intact for a long time. Ditches going deep into the interface, with or without dentin exposure, may increase the risk of biofilm accumulation and secondary caries. It should be weighed out whether marginal sealing, repair, or entire replacement of this restoration would increase tooth longevity and enhance the patients’ quality of life. The occlusal surface of a restoration is examined thoroughly for fracture lines (. Fig. 1.5f). Fractures mostly occur in the isthmus region, between the occlusal and proximal boxes or where the cavity is rather shallow or irregular, causing the restorative to fracture. In general, fractures mostly result from an incorrect cavity preparation. In cases where restorations have been repaired, the junction between the old and new amalgam can be visible, similar to a fracture line. In other situations, parts of the fractured restoration have been lost (. Fig. 1.5g, h). In some cases, the restoration is still in place, but the remaining tooth structure fractures (. Fig. 1.5i). This usually happens when the remaining tooth structure is too fragile and likely to fracture under occlusal load. The restoration should mimic the individual anatomical shape of the intact tooth structure, to allow optimal esthetics and function. Therefore, height and volume of the restored cusps will guarantee adequate chewing efficiency avoiding extrusion of the antagonist (. Fig.  1.5j). Location of the height of curvature on the buccal and lingual surfaces is also very important because it deflects the food bolus, so that the passing food may stimulate the gingival tissues. Restorations with under or overcontour on the buccal and lingual surfaces can result in gingival lesions [54]. Undercontouring may cause food impaction over the gingival tissue, resulting in gingival inflammation or recession in the worst case. Overcontouring deflects food from gingiva and results in understimulation of the supporting tissues, promoting the deposit of biofilm in the cervical region and gingival inflammation [54]. The marginal ridge of a restoration should be adjusted to the height of the adjacent tooth, creating adequate occlusal  

 

 

 

 

 

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embrasures that allow the passage of food toward the buccal and lingual surfaces. Adequate marginal ridges allow proper contact of the opposing tooth in an occlusion of 2:1. Marginal ridges of neighboring teeth at a different height may cause food impaction, resulting in gingival inflammation. Furthermore, the patient may face difficulties when using dental floss [54]. The proximal contact area of Class II restorations should be located in the occlusal third of the proximal surface, with an occlusal embrasure to allow the insertion of dental floss and a tightness to avoid food impaction.

>> The proximal contact area of Class II restorations should be located in the occlusal third of the proximal surface, with an occlusal embrasure to allow the insertion of dental floss and a tightness to avoid food impaction.

The restored proximal surfaces should present a natural convex contour, to guarantee the formation of a perfect contact area with the convex surface of the adjacent tooth. However, when a proximal carious cavitation remains unrestored, adjacent teeth might show the tendency to drift

a

b

c

d

e

f

..      Fig. 1.5  Analysis of the amalgam restorations. a Visualization of the amalgam by translucency; b cervical overhang (arrow); c excess on the margins of the proximal restorations (arrow); d marginal degradation being checked with an exploratory probe; e intense marginal

degradation exposing the dentin; f fracture line. g, h Fracture in the restoration body; i fracture of the remaining cusp; j mesiolingual cusp in amalgam with inadequate height; k inadequate proximal contour; l restoration with open proximal contact

19 Diagnosis and Treatment Planning

g

h

i

j

k

l

..      Fig. 1.5 (continued)

into the open cavity (. Fig. 6.21a, b and . Fig. 1.5k). Restorative treatment without previous orthodontic treatment most likely results in a concave contact area, which is unacceptable for reasons outlined above. Therefore, orthodontic movement of these teeth, for instance, with the help of separation rubbers, is needed before a final restoration is placed. Open interproximal contacts may foster food impaction resulting in discomfort, increased biofilm deposit, and hence gingival inflammation and tooth migration (. Fig.  1.5l). On the other hand, the contact point should not be too tight, in order to avoid the shredding and impaction of dental floss fibers or periodontal trauma induced by  

 

 

excessive force applied during flossing [36]. In situations where repair of the restoration will not be the solution, the total replacement would be necessary. The interproximal contacts are best evaluated with waxed dental floss, exploring its resistance when passing through the contact area, and using a dental mirror in many angulations, keeping it on the lingual position and observing the teeth from the buccal aspect, reflecting the light to the contact region, so that the clinician can see whether there is space in-between the teeth. For that, the contact area should be dry and free of saliva [54]. Creating an anatomic contact point is an important quality factor of a restoration and should be paid particular attention.

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Tip

Creating an anatomic contact point is an important quality factor of a restoration and should be paid particular attention.

unsatisfactory color match because of extrinsic staining or degradation, but also due to color mismatch of the composite or inadequate translucency (. Fig. 1.6a). In regular hybrid composite materials, wear of the organic matrix exposes the filler particles, resulting in a dull appearance of the restoration (. Fig. 1.6b, c). Usually surface repolishing is sufficient to bring back the lost gloss. However, depending on the patients’ diet, consumption of staining substances or tobacco smoking, there might be a tendency toward superficial staining of the restoration. Color mismatch per se is not a biological hazard; therefore, it is solely incumbent upon the patient whether they feel impaired or not. Change in color may also be the result of the degradation of the polymeric matrix, usually an indication for restoration replacement (. Fig. 1.6d–f). Marginal staining is an indicator that there are marginal gaps at the tooth restoration interface associated with microleakage. These can be superficial and not influence the esthetics, or intense, extending deep into the interface. Most superficial stains can be eliminated by repolishing, while the deeper ones might need repair or even replacement of the restoration (. Fig. 1.6g, h). The presence of a marginal stain does not always indicate the need for replacement, unless there is an esthetic impairment that cannot be solved by polishing or when a secondary caries lesion is present (. Fig.  1.6i). Opaque areas, along the cavity margins, and underlying dark shadows may indicate a carious process underneath the restoration alongside the cavity walls. Usually these lesions are active because the ecosystem is nearly sealed and inaccessible to oral hygiene. Progression therefore cannot be controlled, which is potentially detrimental for the hard tissues and tooth vitality [66]. Bacterial growth has been shown to progress faster under composite resin restorations than under amalgam and glass ionomer [67]. However, marginal gap size needs to pass a threshold of approximately 200  μm to allow sufficient fluid exchange for bacterial survival under the restoration [60]. Requirements of the anatomical shape, including contact points, marginal ridges, and shaping of buccal and lingual surfaces that were earlier described, also apply for composite and indirect restorations. (. Fig. 1.6j–l). The esthetic assessment of a restoration performed by a dental professional may differ from the patient’s perspective. As we strive to establish a collaborative partnership with our patients and oblige ourselves to respect patients’ autonomy, it is self-evident that patients exclusively decide whether they suffer from esthetic impairment of a restoration or not. What seems perfect in the eyes of a professional does not necessarily reflect the individual’s perception and vice versa. If the patient voices dissatisfaction, the dentist should evaluate quantifiable medical reasons and whether there is a chance of improvement and how this can be achieved. First, the reasons why restorations have an unfavorable esthetic result should be determined. Probably the reason for an esthetic failure is not the restoration itself but the shade or discoloration of the  

 

Many restorations show some defects in relation to the anatomic shape, but they provide adequate clinical function and do not require replacement. When considering the replacement of an existing restoration, it is crucial whether this restoration has caused damage or is likely to be a risk for the patients’ health. The presence of recurrent caries on marginal areas is detected visually and/radiographically. It is common to find secondary caries lesions in regions where marginal gaps occur in gingival walls, and those indicate replacement [54]. Lesions on the buccal or lingual walls are generally not detectable in radiographic images due to superposition of the radiopaque restorations. For details about diagnosis of caries lesions, see 7 Chap. 3. Occlusal contacts of a restoration are evaluated to determine whether they are serving its chewing function, without causing a symptomatic or pathogenic occlusion. In the absence of gingival inflammation, a traumatic occlusion does not trigger bone loss. However, in the presence of a periodontal disease, the traumatic occlusion may intensify progression of the disease and bone resorption. Restorations with traumatic occlusal contacts should be adjusted or replaced. On the other hand, restorations without occlusal contact may foster overeruption of the antagonistic tooth [66]. The desirable surface roughness of a restoration should be similar to the intact tooth surface, giving the patient comfort and preserving gingival health. Rough areas, next to the gingival margin, promote an increased biofilm deposit and should be repolished. On damaged restorations, polishing may not be efficient, and replacement is supposedly the best solution. Restorations with gingival margins violating the biological width are associated with gingival inflammation and bone resorption. Surgical crown lengthening is indicated when the cervical restoration margin invades the connective tissues [20]. Cast metallic restorations should essentially be evaluated the same way as amalgam restorations. However, they hardly suffer from external degradation, and the main problems happen in the marginal region. Other than amalgam that tend to fracture when extended secondary caries is present, they do not present any visual signals unless the restoration is displaced. Direct tooth-colored composite restorations and indirect ceramic or composite restorations should be assessed analogously. Other than metallic restorations, color match is a quality parameter here. It is highly appreciated to have restorations not clearly discernable as such that perfectly blend into the natural dentition. Some restorations present an  

 

 

 

 

21 Diagnosis and Treatment Planning

remaining tooth. In this case, replacement may lead to a restoration with the same unsatisfactory result. In case a restoration is medically impeccable from the dentist’s but unpleasant from the patient’s perspective, we have to perceive patients’ concerns notwithstanding. When we intend to replace a restoration because of mere esthetic matters, the clinician needs to inform the patient in detail about

risks and side effects, for instance, additional preparation of the tooth may lead to pulpal symptoms or even an accidental pulp exposition [66]. >> What seems perfect in the eyes of a professional does not necessarily reflect the individual’s perception and vice versa.

a

b

c

d

e

f

..      Fig. 1.6  Defects on composite restorations. a Improper restorations by the lack of the color match; b large class IV restorations performed on the central incisors with hybrid composite at the 6th year recall, with satisfactory shade but lost of the surface gloss; c class I restorations with loss of gloss and rough surface; d–f color changes in the body of the restoration. g, h Marginal staining due to lack of

marginal sealing; i deep marginal staining with a darkened aspect under the restoration; j restoration with inadequate color/translucence match and anatomic shape; k overhang of restorative material trespassing the contour on the buccal surface of the first molar; l aspect of gingival inflammation immediately after the overhang removal

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g

h

i

j

k

l

..      Fig. 1.6 (continued)

Tip

Always remember that a patient’s perception may differ significantly from that of a clinician and medical requirements may vary too.

1.3.3.4

Occlusal Analysis

Before planning restorative treatment, it is advisable to analyze the occlusal conditions. Any interferences of intended restorations on the occlusion should be considered beforehand, as well as the impact occlusal conditions will have on

the treatment plan [66]. In complex cases, occlusion analysis is preferably performed on plaster models. >> Before planning restorative treatment, it is advisable to analyze the occlusal conditions.

The static occlusal analysis should be registered in maximal intercuspation, including the vertical relation of molars and canines (Angle’s Classes I, II and III), including overbite and overjet. The absence of teeth, migration and inclination of crowns, as well the presence of turned or overlapped teeth should be registered. Midline shift of the mandible and the maxilla and the shape of the occlusal plane are to be registered.

23 Diagnosis and Treatment Planning

Functional evaluation of the dynamic occlusion, during lateral movements to the right and left as well as protrusion, should be executed. Additionally, the difference between position of the jaw in centric relation and centric occlusion is evaluated. During lateral movements, disocclusion guide is registered as to canine or group guide and how much anterior guide is involved. Contacts that may interfere on the non-working side need to be identified and possibly adjusted. The presence of deviation during opening or temporomandibular joint (TMJ) cracking is regarded as a potential indicative for temporomandibular disorder [54]. The reasons of abnormal occlusal surface wear need to  be explored. Most probably, the underlying causes are parafunctional habits such as bruxism. Matching wear facets on the opposing teeth because of parafunction or a general wear on the occlusal surface can be noticed. The treatment of those patients may include the use of protective occlusal splint so that the further tooth wear is slowed down. Results of the occlusal analysis are registered on a clinical chart and included for treatment planning (. Fig.  1.14). Positive aspects of the occlusion need to be preserved and should not be altered during treatment. However, improvement of the occlusal relation is desired, and abnormalities should not be perpetuated on the restorative treatment [54, 66]. Number and position of the occlusion contacts in the position of maximal intercuspation, intensity of the biting force, and the way that the opposing teeth occlude and disocclude on excursive movements may influence the choice of a restorative material. When the occlusal stress is high, the dentist rather selects restorative materials that are more resistant, performing the restorations in a way that they can allow more strength on the load areas [66].  

1.3.4

Esthetic Evaluation

During clinical examination, it is fundamental to explore the patients’ estimate of dental esthetics. According to Rufenacht [58], the smile represents the most primitive and purest form of communication between human beings, appearing in the early youth, observable already in babies. A smile as all facial expressions transmit feelings and emotions. A pleasant smile can produce an aura that improves the beauty of a face, and it is part of the qualities and virtues of the human personality. The perception of those qualities generates the power of attraction, a necessary component for success in our society [58]. >> According to Rufenacht [58], the smile represents the most primitive and purest form of communication between human beings, appearing in the early youth, observable already in babies.

As beauty is primarily a matter of personal taste, modified by social norms, its visualization is a subjective experience [66]. However, some objective parameters can be used to identify the most expressive changes that may compromise oral esthetics. Many characteristics of teeth and gingiva, such as

..      Fig. 1.7  Relation of the occlusal frontal line, commissural line, interpupillary line, and the facial midline

tooth dimension, clinical crown width-to-length ratio, color, shape, and gloss, among others, as well as gingival shape, contour, embrasure, zenith, and height (position or level), are part of what is called microesthetics. These parameters cannot be analyzed separately, although being very important to result on a pleasant smile (miniesthetics) but in association with a harmonious face (macroesthetics) to result in good self-esteem (hyperesthetics) [13]. Dental and gingival esthetics are inseparable to create a pleasant smile. Therefore, good restorations cannot compensate for (esthetic) problems of the surrounding soft tissues [41]. The opposite turns out to be true as well. The most common esthetic problems are changes in tooth color, contouring of anterior teeth (length, width, incisal edge shape, and axial contour), unesthetic position or space between the teeth, caries lesions or defective restorations, excessive buccal corridor space, a gummy smile, etc. [66]. Apart from these factors, asymmetry creates visual tension on the observer side. The occlusal frontal plane or line is a connection between the tips of both maxillary canines. This line should be parallel to the interpupillary line and to the line that connects both labial commissures, the commissural line (. Fig. 1.7). The facial midline is perpendicular to those two lines [58]. The dental midline is traced between both maxillary central incisors, and it should be perpendicular to the occlusal frontal line (. Fig. 1.8a, b). Other than that, it should be coincident with the facial midline of the patient, even though small asymmetries do not impair a great deal of the esthetic. The facial midline and dental midline coincide in only 70% of the people, while the dental midlines of the upper and lower arches do not coincide in almost three-quarters of the population [41, 45]. The borderline of the dental crown and the gingival tissue determines the so-called gingival line, which also interferes with the harmony of the smile. For its evaluation, a straight line is traced from the highest point of the interface between the tooth and the gum, known as the gingival zenith, from the right to the left maxillary canine (. Fig. 1.9a). The tooth-­ gum interface of both central incisors should be on this line,  

 

 

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a

b

..      Fig. 1.8  Relation between the dental midline and occlusal frontal line. a Midline perpendicular to the occlusal frontal line; b midline inclined in relation to the occlusal frontal line

a

b

..      Fig. 1.9  Gingival contour. a Gingival line; b gingival zenith

while the lateral incisors are approximately 1.5  mm below this line [2, 66]. The gingival line is preferably parallel to the occlusal frontal line. The gingival zenith of the homologous teeth should be on the same plane, guaranteeing the symmetry of the dental-gingival composition. Since the long axis of the anterior maxillary teeth is slightly inclined to the distal, the gingival contour does not form a symmetric arch, and the gingival zenith is slightly displaced to the distal side (. Fig.  1.9b) [66]. Visibility of the gingival contour during a broad smile largely contributes to facial esthetics. Corrections on the gingival contour can be obtained by surgical techniques, such as gingivectomy or coronally advanced flaps. The relation between lips and teeth is also fundamental for the beauty of a smile. The quantity of dental exposition while smiling depends on many factors such as muscle contraction, the gingiva level, skeleton particularities, tooth shape, and the presence of dental wear [58]. The incisal edges of the anterior maxillary teeth form a curve, called incisal line or smile line, with the lowest part in region of the central incisors. During a maximum smile, those edges are supposed to softly touch the lower lip (. Fig. 1.10a, b). That means the  

 

curve formed should be parallel to the curve of the lower lip [58, 66]. The degree of curvature of the incisal line is more prominent in women than in men [58]. The incisal edges should never be hidden by the lower lip, as shown in . Fig. 1.10c. In this case, it is probable that there is a problem with the vertical position of the maxilla, as a dental overeruption or a very large maxilla on the vertical way [66]. The presence of an inverted incisal line curvature is generally related to aging due to anterior teeth wear (. Fig. 1.10d). If there is a reverse incisal curve in relation to the lower lip or a very large space between the lower lip and the edges of the anterior maxillary teeth, the esthetic might be improved increasing the length of the incisal edge [66]. The line formed by the upper lip border is called upper lip curvature or lip line. On a maximum smile, the upper lip should translate up to the gingival line, which happens in 70% of the population. The ideal upper lip curvature is obtained when the lip reaches the edge of the interdental gum (. Fig. 1.10a, b) [58]. About 10% of the people have a very high upper lip curvature. Every time this line surpasses more than 2 mm of the gingival line, an esthetic impairment is noticed, causing the so-called “gingival smile” or “gummy  

 

 

25 Diagnosis and Treatment Planning

smile” (. Fig.  1.10e) [66]. The modalities for treatment of this situation are limited. Orthodontic intrusion and surgical crown exposition are treatment options to be considered [58]. Another option is the application of botulinum toxin (Botox-A) in the muscles that control the upper lip movement, which is a minimally invasive and effective option. About 20% of the individuals have a very low upper lip curvature (. Fig. 1.10f) [66, 69]. Every time the upper lip does  

 

not translate up to the gingival line during a maximum smile, a loss of the smile dynamics will result [66]. If the patient presents an asymmetric movement of the upper lip when smiling, this will result in excessive one-sided gingival exhibition, besides misalignment between the ­commissural and the interpupillary lines (. Figs. 1.10g and . Fig. 14.42a). In this case surgical crown lengthening may help to improve the esthetics, although Botox application,  

 

a

b

c

d

e

f

..      Fig. 1.10  Esthetic analysis of the maximum smile. a Incisal edges of the anterior maxillary teeth touching the lower lip and the upper lip curvature exposing the gingival papilla; b small exposure of the gingival tissue and the presence of a small and homogeneous space between the edges of the maxillary anterior teeth and the lower lip; c incisal edges of the maxillary anterior teeth covered by the lower lip;

d inverted incisal line; e excessive exposure of the gingival tissue; f low upper lip curvature. g Asymmetric movement of the upper lip, greater on the left side; h straight upper lip curvature; i inverted upper lip curvature; j inclined occlusal plane downward on the right side; k excessive buccal corridor; l loss of gradation because of the inadequate position of the teeth 24 and 25

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g

h

i

j

k

l

..      Fig. 1.10 (continued)

notwithstanding its temporary effect, involves less risk and costs. If the asymmetric movement occurs on the lower lip, a greater space between the incisal edges and the lower lip will result in one of the sides, impairing the symmetry of the smile. In those cases, the maxillary teeth can slightly be lengthened to compensate for this problem [66]. In repose or when the patient says “M,” there should be an exhibition of 3–4 mm of the incisal edge of the central maxillary incisors in young women or 1–2  mm in men. After 40 years of age, the quantity of exposition of the incisal edge decreases in about 1 mm per decade, while it increases the exposition of the lower incisors [58, 66, 71]. When the patient says “E,” a space between the upper and lower lips will form.

If less than 50% of this space is occupied by the maxillary central incisors, probably, a lengthening of the tooth will improve the esthetic of the smile. On the other side, if more than 70% of space is occupied by the maxillary incisor, the lengthening of the incisor will not be pleasant [66]. When the patient says “V” or “F,” the edges of the upper central incisors should slightly contact the border of the lower lip [66]. From the middle to the corners of the mouth, the upper lip curvature should form a curve facing upward, due to the activity of the facial muscles during the smile (. Fig. 1.10a–c). However, some people have a straight (. Fig. 1.10h) or even downward curvature (. Fig.  1.10i), affecting the attractiveness of those smiles. In those cases, some improvement can  

 

 

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27 Diagnosis and Treatment Planning

a

b

c

d

..      Fig. 1.11  a Incisal embrasures with progressively increasing sizes as they distance from the midline; b incisal embrasures with similar sizes, giving a less natural aspect and an aged look; c cervically located

contact, causing a very large incisal embrasure; d very small contact causing a dark triangular space

be obtained using techniques of muscle training when the other components of the smile do not compensate for this deficiency [58]. The incisal edges of the incisors and cusp tips of posterior teeth form the occlusal plane, which is actually a curved surface. When analyzing the esthetics of a smile, the cuspal tips of the maxillary posterior teeth should present a visual progression, in general upward, starting from the tip of the canine cusp, without high or low points. The right and left sides must be symmetric [66]. In . Fig.  1.10i, the occlusal plane is inclined downward on the right side, breaking the harmony of the smile. The space between buccal surfaces of the posterior maxillary teeth and the cheeks is called buccal corridor, which becomes visible during smiling and mouth opening. During a broad smile, the corridor is almost completely occupied by teeth with a small lateral space toward the cheek. A constricted maxillary arch (. Fig. 1.10k) can cause an excessive buccal corridor and thereby impair the esthetics [66]. Conversely, the complete absence of the smile corridor can also negatively affect the esthetics. Facing a patient from the front, as the eyes move laterally from midline, each tooth must seem proportionally thinner than its mesial neighbor. This is called the principle of gradation [39]. The distal half of the maxillary canine must not be

visible when viewing the patient from the front. Inadequate contouring or misalignment may break the front teeth harmony (. Fig. 1.10l) [66]. The proportion between height and width of each individual tooth also influences the dental esthetic and is further discussed in 7 Chap. 14. The size of the incisal and gingival embrasures changes with age. In young individuals, the incisal embrasures are large and open increasing from the midline to the canine, while gingival embrasures are little visible (. Fig. 1.11a). With aging, the size of the incisal embrasures decreases and may disappear completely because of tooth wear (. Fig.  1.11b). Simultaneous to the incisal wearing, gingival papilla suffers from recession, increasing the size of the gingival embrasures. In some cases, abrasion happens before gingival recession, leaving the teeth shorter and apparently wider. In other cases, the gingival recession happens first, giving the teeth an apparently longer appearance. Both cases contribute to an aging of the smile [7].

 

 

 

 

 

 

>> The size of the incisal and gingival embrasures changes with age. In young individuals, the incisal embrasures are large and open increasing from the midline to the canine, while gingival embrasures are little visible.

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If the interdental contact is positioned too far away from the incisal area, a too large embrasure leaves an unnatural appearance (. Fig. 1.11c). If the contact does not extend far enough toward the gum, the interproximal space will be open, creating a dark triangle (. Fig. 1.11d).  

 

>> Aging has a tremendous impact on teeth, alveolar bone, and connective tissues.

1.4

Evaluation of Caries Risk

Untreated dental caries is the most prevalent chronic condition worldwide [34]. It is known that the etiology is multifactorial and associated with behavior, socioeconomic status, and physical, environmental, microbiological, and other host-related factors. Each patient can present a combination of different factors that will determine the characteristics of the current disease and the likelihood of progression referred to as caries activity [54]. The higher the number of risk factors, the higher his caries risk will be. However, caries risk assessment is not a standardized process in clinical practice and is based on various techniques; the most prevalent is the visual-tactile assessment [21]. This evaluation can help to guide the treatment. Elimination or control of etiological factors should be the primary goal in high-risk patients, whereas monitoring and re-evaluation might be sufficient guidance for patients with lower caries risk [54]. >> Untreated dental caries is the most prevalent chronic condition worldwide. It is known that the etiology is multifactorial and associated with behavior, socioeconomic status, and physical, environmental, microbiological, and other host-related factors.

Caries risk factors can be divided into oral and non-oral parameters. For the oral aspects, dental anatomy can foster biofilm deposit (presence of deep fissures and pits), no contact with fluoride, inadequate oral hygiene, presence of restorations (that may indicate a past history of high caries activity), and the presence of defective restorations that allow the deposit of biofilm, contributing to a higher caries risk. Nonoral factors, associated with an increased caries risk, are age, low socioeconomic status, systemic diseases (Sjogren’s syndrome, diabetes, chronicle stress, radiotherapy, etc.), intake of medications that reduce the salivary flow, high consumption of carbohydrates, smoking [51], and alcohol abuse [53], besides systemic debilitating diseases that reduce self-­care ability [54]. Among all the factors, the most important indicators for caries activity are the presence of active or recently treated caries lesions, a great quantity of cariogenic biofilm, frequent sugar consumption, and low saliva flow [66, 72]. In patients with active lesions, microbiological biofilm analysis, evaluation of dietary habits, and salivary flow are important to assess the susceptibility to caries and prediction of the likelihood of success for any restorative treatment. Salivary flow rate can easily be determined, asking the patient to chew on a gum or a piece of wax for about 5 min,

spitting inside a graduated cylinder of 20  ml. To eliminate the foam of the saliva and have a precise measurement, some drops of dimethicone can be added to the collected content. This addition does not interfere with the measurement because the volume used is very small [18]. The result is divided by 5, which is the flow rate per minute. The normal values must be between 1.5 and 3 ml/min. Values between 1 and 1.5  ml/min indicate a slight hyposalivation, while a value between 0.5 and 1  mm/min indicates a moderate hyposalivation. A flow between 0.05 and 0.5 indicates a severe hyposalivation [18, 68]. Based on a 7-day dietary protocol, patients’ nutrition habits can be evaluated. Presenting a full nutrition record, including the amount of food, snacks, and beverages to most patients, is a very intimate and personal matter. A trustful doctor-patient relationship is therefore the ultimate prerequisite for unaltered protocols. Professionals must not be judgmental and demoralizing or must not point an incriminating finger at a person but should offer help and support patients who want to change their habits for the better. Motivational interviewing is a counseling method that gradually helps patients to develop discrepancies and establish solutions for behavior change [25]. In dentistry, there are numerous fields of application, starting with oral hygiene motivation and diet counseling, culminating in smoking cessation, or establishing a responsible drinking behavior. Biofilm control is one, if not the key, issue in the prevention of dental caries. Therefore, it is a standard practice to register plaque formation over time. Many indices are proposed for daily routine or epidemiologic purposes (API, QHI and PI, PFRI). The O’Leary index, for example, is based on the presence or absence of biofilm on four surfaces (buccal, lingual, mesial, and distal). After disclosing the biofilm with a dye, presence of plaque is marked the diagram as shown in . Fig. 1.15 [52]. Missing teeth should be marked with an X on the diagram, so they are not taken into consideration for the calculation. The result is expressed as the percentage of surfaces with biofilm in relation to the entirety of examined, surfaces using the following formula:  

O¢Leary Index =

Quantity of dyed surfaces ´100 Total surfaces analyzed ( number of present teeth ´ 4 )

The use of a plaque index objectively visualizes biofilm deposit and enables monitoring changes over time. Indices between 0% and 12% are acceptable; values between 13% and 23% are considered increased. Values from 24% to 100% express ineffective oral hygiene. Results of a biofilm index, however, are just one tessera of the complex caries risk assessment. In order to obtain an overall impression, as many possible risk factors should be gathered and weighed. The software Cariogram integrates risk parameters calculating the probability of future lesion development. However, it was found to be inferior to identify high-risk patients compared with clinical judgment based on decayed surfaces and incipient lesions [29].

29 Diagnosis and Treatment Planning

Biofilm indices can be collected on several occasions during treatment course and on every recall appointment when appropriate. Improvement of oral hygiene is, like any other behavioral change, a delicate matter that cannot be achieved by simply telling the patients to do so. Instructions can be helpful for those who are capable and willing to implement new routines. Frequent recall interval, including professional tooth cleansing, is an effective alternative for those who have a lack of motivation or are manually incapable of maintaining efficient oral hygiene. Tip

Try to gather as many risk and protective factors, and, for practicality, organize your patients into groups of high, moderate, or low caries risk. Re-evaluate factors in defined intervals.

1.5

General Treatment Plan

The treatment plan is a series of treatments planned to eliminate or to control etiological factors, to repair existing damage and create a functional oral environment, possible to be maintained [54]. A precise prognosis for each tooth and the general oral health of the patient is fundamental for its success. To establish a treatment plan, the dentist should be capable to foresee the outcome of treatment procedures, regarding best available evidence as well as risks and side effects of different treatments, based on the individual risk of a patient [54]. One principle of medical ethics is to ensure patienty’s safety, preventing any injury to them (non-maleficence), which also applies to dentistry [11]. Clinicians should have profound knowledge of the current evidence about risks and benefits of treatments being offered. As mentioned above, invasive therapy is flanked by more or less unwanted side effects that need to be taken into consideration, as well as the wanted benefits of operative treatment. Replacement of a restoration causes additional substance loss, leading to larger restorations. This may happen many times during the patient’s life, resulting in what is called the repetitive restorative cycle, which leads more invasive restorations with every treatment, endodontic treatment, and tooth loss as the final consequence and worst-case scenario [15, 54]. >> One principle of medical ethics is to ensure patienty’s safety, preventing any injury to them (non-maleficence), which also applies to dentistry [11]. Tip

Invasive treatment should be considered with caution, since the so-called repetitive restorative cycle leads to continuous substance removal and premature loss of teeth as final consequence.

Having an initial list of patient-centered problems and knowing about the patients’ preferences, the clinician should propose treatment alternatives to the patient. Following the rules of shared decision-making, advantages and risks of each option should thoroughly be evaluated [5]. Shared decision-­ making basically aims at achieving mutual agreement about the clinical procedure, diagnostic methods, and therapy of choice between the caregiver and the patient and/or their legal guardians. Both doctor and the patient rather act as partners, trying to overcome the natural asymmetry of knowledge. The clinician should enable the patient to make a self-determined therapy decision and to comprehend the risks and benefits that are associated with this choice or any other alternative. The outcome of this process is ideally an informed choice that is recorded on a chart (. Fig. 1.16). The treatment process should follow a reasonable order. The sequence of treatments is ordered as follows: systemic phase, urgency phase, control phase, re-evaluation phase, definitive phase, and maintenance phase [22, 54, 66]. Following this treatment concept will guarantee a structured and biological sequencing of therapy steps.  

>> Shared decision-making basically aims at achieving mutual agreement about the clinical procedure, diagnostic methods, and therapy of choice between the caregiver and the patient and/or their legal guardians.

Objective of the systemic phase is to determine whether there is a medical risk for the patient or for the professional team during dental treatment. According to their physical conditions, patients can be classified according the American Society of Anesthesiology (ASA), employed to evaluate surgical risk [23]. According to this system, the patients are classified into six categories: 55 ASA I – Healthy patient, without any physiological, biochemical, or psychical disturbs and little or no anxiety. No risk for dental treatment. 55 ASA II – Patient with slight or moderate systemic and controlled diseases, not compromising his normal activities. Conditions may affect surgical and anesthesia procedures. Healthy patients (ASA I) with extreme anxiety or fear for the dental treatment can also fall into this category. They present a minimum risk during treatment. For example, well-controlled diseases as prehypertension, non-insulin-dependent diabetes, epilepsy, asthma or thyroid problems, patients ASA I with active allergies, breathing problems, or pregnancy. They might need a previous medical consultation. 55 ASA III – Patients have severe systemic diseases that are hard to control, limiting their normal activities, but it does not incapacitate them, presenting impact on the surgical procedures and anesthetics. There are, for example patients who suffered or currently suffer from angina pectoris, myocardial infarction, cerebrovascular accident, congestive heart failure more than 6 months before the dental appointment, hypertension, controlled insulin-­dependent diabetes or chronic obstructive

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pulmonary disease of little intensity. They need a previous medical consultation. 55 ASA IV – Patients with incapacitating life-threatening systemic diseases with great impact on surgical anesthesia. These patients have a significant risk during dental treatment; hence, any elective treatment should be dropped or postponed. 55 ASA V – Dying patients with life expectancy less than 24 h notwithstanding any medical treatment. They have terminal diseases and are almost always at the hospital. Dental treatment is definitively contraindicated, but an emergency palliative care might be provided in the hospital. 55 ASA VI – Declared cerebral death and kept alive for organ donor.

toration or integration into full mouth rehabilitation; or they might have had a negative response and should rather be extracted. Then, the rehabilitating plan should be modified, including possible prosthetic replacement of the mentioned teeth. Control of bacterial biofilm usually results in improvement of gingival health and a reduced risk of developing further caries lesions. In some cases however, strategies could not have been efficient and may require modification before the next step. At the end of this phase, the patient should be orally healthy without an active disease [22]. The corrective treatment focuses on restoring masticatory function and esthetics concerning the patients’ expectations in these matters. A favorable prognosis is highly depending on controlling the disease causing factors in the longer term and hence requires informed patients who are willing and capable to maintain good oral health [22]. After completion of the systemic phase and in the event a Another reason to change the initial treatment plan may be patient can be safely treated, urgent treatments are usually financial matters. Treatment costs may actually not fit the given the first priority [22]. The urgent phase is dedicated to patient’s financial situation at that moment. It is wise to pain relief and infection control. These conditions should be address costs for dental treatment overtly and nonjudgmeneliminated prior to realization of any further treatment [66]. tal and provide less expensive treatment options whenever Esthetic problems can also be considered as urgency treat- possible. No treatment at all or postponing cost-intensive ment; in particular, when anterior teeth are involved [22]. procedures is usually preferable to losing a patient due to Another important reason to treat urgent problems first is obscure pricing strategy. that, in general, patients are not capable to take adequate Before follow-up maintenance, the definitive or correcdecisions when they suffer pain [22]. tive phase is the final phase of the treatment concept [54, 66]. When the patient is pain-free, the treatment plan might It aims to reconstitute the dentition to a comfortable, esthetic, be re-evaluated regarding the definitive phase. It might hap- and functional situation, as defined by the patient’s demands pen that patients take different decisions when pain and dis- [22]. Many procedures that fall into the control phase, like comfort are no longer present. During the control phase, restoration of carious teeth, may control the disease and act etiological risk factors of a disease are eliminated or reduced as definitive restoration at the same time [66]. In addition, [66]. In order to achieve and later on maintain healthy oral some procedures improving esthetic and function, such as conditions, an individual program is designed to establish prosthetic, orthodontic, cosmetic restorative, or surgical oral hygiene measures and possibly support the patient to treatments, may be indicated. This part is frequently the most refrain from health endangering habit [54]. The ultimate suc- cost intensive. cess of any rehabilitating treatment plan depends on how The maintenance phase aims to stabilize treatment results well diseases are controlled over time [22]. Treating the and hinders diseases to reoccur. The frequency of the re-­ symptoms of a disease is doomed to fail since persisting etio- evaluation intervals will greatly depend on the patient’s risk logical factors will jeopardize the treatment outcome [22]. to oral diseases. A longer interval of approximately 1 year can Examples for causal-therapeutic measures comprise infec- be recommended for patients with a very low documented tion control, establishment of oral hygiene, periodontal and risk for developing periodontal diseases and caries lesions endodontic therapy, (provisional) restoration of open cavities [54]. On the other side, high-risk patients may benefit from or defective restorations, removal of cervical overhangs, and more frequent recall intervals, for example, every 3–4 months extraction of hopeless teeth. Based on the individual caries [54]. It is expected that this phase is the longest of the treatrisk, the dentist should develop an individual treatment plan ment, and it is focused on keeping the oral health for the aiming at arresting and preventing caries and periodontal whole life of the patient [22]. diseases, as well as any other oral disease or detrimental conBitewing radiographs may flank oral examination in risk-­ dition [54]. Again the definitive treatment should be re-­ orientated intervals as well. There is no general agreement evaluated after this phase and amended if necessary [22]. about the frequency of radiographic re-evaluation. The higher the risk for the development of new lesions and the >> It might happen that patients take different decisions more differentiated the treatment concept for caries lesions when pain and discomfort are no longer present. are, in particular in non-operative care, the more frequent Time should be allowed between the control and definitive bitewing radiographs may be beneficial for the patient. On phase in order achieve oral conditions that are free of pain the downside, a higher frequency of radiographs may lead to and inflammation. For example, teeth with pulpal or peri- overdiagnosis and overtreatment, initiating the abovemenodontal doubtful diagnosis may have responded positively to tioned repetitive restorative cycle [31]. Frequently patients causal treatment and may be considered for a definitive res- are skeptical about radiographic examinations because of

31 Diagnosis and Treatment Planning

radiation exposure, which has to be taken into consideration for the decision whether and, if yes, how frequent bitewing radiographs will improve oral health.

Tip

The treatment concept enables clinicians to structure a treatment into biological stages, in a logical order, aiming at creating and maintaining healthy conditions and improving a patient’s oral health-related quality of life.

>> Frequently patients are skeptical about radiographic examinations because of radiation exposure, which has to be taken into consideration for the decision whether and, if yes, how frequent bitewing radiographs will improve oral health.

1.6

Planning Restorative Treatment

Planning an individual and tooth-specific restoration is the final step in the restorative treatment plan. It requires the consideration of four main factors and a number of modifying factors. The main factors are quantity and shape of the remaining tooth structure, functional requirement of an individual tooth, and the superordinate objective of the treatment plan in general [66]. Above all this, it is of course the patients’ demands that largely provide the direction which kind of restoration is preferred. The quantity of remaining tooth structure determines its resistance and possibility of retention for the restorative material and thereby influences the drawing of the final restoration. Since longevity of a restoration is an ultimate treatment goal in most scenarios, the design of a restoration should prevent fracture and displacement. Small and medium Class II cavities can easily be restored with amalgam or resin composites. However, when the amount of lost tooth structure is greater than one-third of the intercuspal distance, the tooth is more susceptible to fracture. Indirect restorations claimed to be a solution for those problems. However, modern concepts of adhesive dentistry advocate the unlimited use of direct composite restorations even in endodontically treated teeth [44]. Doctrines differ considerably, yet direct adhesive suppresses increasingly indirect restorations. Besides the width, the depth of the preparation is also fundamental. On large and deep preparation, the need to protect the cusps from fracture is greater either with direct amalgam restorations or with indirect restorations. In anterior teeth, the amount of the remaining tooth structure as well will determine the success of a restoration. Direct composite restorations are sufficient in most cases and can be seen as the standard anterior restoration. In cases of severe loss of tooth structure, extreme malpositioning or overal esthetic impairment, veneers, or full crowns may be indicated. However, masters of their craft are capable to solve

even the most complex cases using direct restoration techniques [66]. When choosing the material for a dental restoration, it needs to be considered whether a patient suffers from excessive occlusal load and parafunction or not. Patients with bruxism, deficient disocclusion guide, worn facets, or severe attrition due to heavy occlusal stress are probably not the best candidates for delicate and fragile ceramic restorations. Therefore, signals of excessive functional load should be carefully evaluated during the clinical exam [66]. Even though the indication of indirect metallic restoration has decreased significantly, they present excellent properties and acceptable longevity [48]. They may also be favorable on preparations with deep subgingival margins. Indirect restorations are fabricated and polished outside the mouth, which makes it easier to obtain a convex and smooth contour compared to direct restorations [54]. The longevity and hence the clinical success of restorations depend on numerous variables including materials-, patient-, and dentist-­related factors [27]. >> The longevity and hence the clinical success of restorations depend on numerous variables, including materials-, patient-, and dentist-related factors.

Indirect restorations can be performed with light-curing composites designed for laboratorial use, feldspar porcelain, pressed ceramic, or ceramic/composite blocks for computer-­ generated restorations (computer-aided design/computer-­ assisted machining  – CAD/CAM). They present physical properties that are superior in relation to the direct composite restoration. However, they are associated with higher costs, because materials are more expensive and laboratorial work and more treatment time are required. Even though composites for laboratorial use have improved resistance, no difference regarding longevity compared to direct composite restorations can be found [19]. The restorations of feldspar porcelain are an alternative for large Class II cavities and have predictable esthetics, even though it has a relatively high incidence of fractures, especially when they are exposed to occlusal stress. They also wear the opposing tooth because of higher microhardness in relation to natural enamel or other restorative materials. Pressed ceramics offer an excellent marginal adaption, low abrasion of the opposing tooth, and superior resistance if compared to the indirect composites or feldspar porcelain. It offers an alternative to indirect metallic restorations. The restorations made with CAD/CAM technology are indicated from Class I and II cavities up to single crowns and have higher resistance to occlusal stress and low abrasion than direct composites [54]. The choice of a restorative material has to be in line with the superordinate treatment plan. For example, restoration of a tooth that later on serves as an abutment for prosthetic rehabilitation might be different from a permanent restoration without further treatment [66]. After shared decision-making and after the patient has made an informed choice on the treatment, the whole process should be brought to a logical order. The adequate

1

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1

C. R. G. Torres et al.

sequence is many times critical for the success of the treatment, avoiding unnecessary complications. Most of the restorative treatments will be in the phase of disease control or definitive rehabilitation. Restorative interventions aiming to control the disease mostly comprise direct restorations with amalgam, composites, or glass ionomer cement. The treatment sequence should be coordinated with the patient’s preferences. Symptomatic teeth, those with severe decay or esthetically compromised teeth, are usually treated first. However, it is highly recommended to fulfill a patient’s chief complaint at a very early stage, signaling a patient-centered and professional demeanor. Restorative procedures in the definitive rehabilitation phase may go beyond the necessity to stabilize the disease and may include treatments destined to improve esthetics, for instance, placing veneers for closing diastemas or offering adequate function by replacing missing teeth [66]. The treatment sequence should be registered on the clinical chart as presented in . Fig. 1.16.  

1.7

Interdisciplinary Aspects

Dentistry today consists of highly specialized disciplines, which bring up the need for interdisciplinary teamwork. In complex cases where more than one dentist is involved, one colleague has to have the coordinating role. Usually the family or general dentist takes the lead and refers patients to specialists. >> Dentistry today consists of highly specialized disciplines, which bring up the need for interdisciplinary teamwork.

Periodontal treatment frequently precedes restorative treatment, creating more favorable environment and facilitating operatory maneuvers. Teeth with unsatisfactory periodontal prognosis should not be considered for comprehensive prosthetic rehabilitation. Restorations may precede periodontal treatment in inflammation-free periodontal conditions or in the presence of open cavitation or lost restorations. Treatment of deep caries lesions may require a temporary filling, to promote oral hygiene capability and prevent from caries progression. Self-explanatory endodontic treatments should be performed prior to definite restoration and periodontal treatment. If surgical periodontal treatments become necessary, indirect restorations and prosthetic measures are postponed until complete healing of the operated area. Teeth planned for indirect restoration should receive temporary restorations before periodontal surgery, defining the position of the margins and improving access for surgery. Preparations which margins invade the biological width should be submitted to crown lengthening surgery, before a definitive restoration is placed. A minimum of 3 months and possibly up to 6 months is necessary before initiation of definite prosthetic treatment [32]. Orthodontic pretreatment may be the prerequisite to achieve optimal function and/or esthetic results in complex cases. Minor interventions comprise single tooth movement, uprighting molars, or extrusion therapy. Caries and peri-

odontal diseases need to be controlled adequately before comprehensive orthodontic treatment over a longer period. Indirect restorations should preferentially be postponed until removal of orthodontic appliances [54]. Surgical interventions like tooth extraction or removal of impacted teeth should precede restorative treatment. This is particularly important in the cases of third molars, where, as a side effect, surgical procedures can lead to damage or displacement of restorations on second molars [54]. Occlusal analysis can evince a lack of disocclusion guide or interferences, which might be treated before restorative and prosthetic procedures. If necessary, the occlusal adjustment is initiated before the definitive phase [54]. It might be easier to place direct restorations before indirect ones; however it also works in reverse order. 1.8

Oral Health Records

A detailed documentation of anamnestic and patient-related information is fundamental for quality control when planning the treatment. This also applies for documentation of treatment procedures and incidents, as well as discussions and telephone calls with the patient or relatives. The patient file serves as the basis in case of legal disputes, as documentation to a third-party payment, and in the case of forensic identification [54, 63, 66]. Patient’s oral health records should contain a central document, which might be flanked by supplementary documents [3]. Additionally intraoral camera image and photography are excellent features for documentation [54, 66]. Documentation should follow the statutory requirements of the Federal Council that control a clinician’s activity in each country [3]. The complete oral health record allows the clinician to analyze the case, even when the patient is not present, and to anticipate the treatment at the following appointment [54, 66]. >> A detailed documentation of anamnestic and patient-related information is fundamental for quality control when planning the treatment. This also applies for documentation of treatment procedures and incidents as well as discussions and telephone calls with the patient or relatives. The patient file serves as the basis in case of legal disputes, as documentation to a third-party payment, and in the case of forensic identification.

Every clinical chart contains the clinician’s and the patient’s identification, patient’s master data, anamnesis, clinical findings, treatment plan, and records about the progress and intercurrences during the treatment. It is mandatory to have the clinician’s identification including name and registration number of the Federal Dental Council, on all printed papers. As to patients’ identification, the following information are essential to meet legal requirements according to each country: complete name, address, national identification number, social security number, health insurance information, place and date of birth, civil status, nationality, and gender. The way a patient chose a specific clinician should also be

33 Diagnosis and Treatment Planning

r­ egistered. When the patient is underage or has been declared incompetent, it is necessary to register contact data of his legal guardian. It may be important to record the name of clinicians whom the patient previously attended and, if possible, date and place of attendance (. Fig. 1.12). Anamnestic records contain the chief complaint, the history of the present illness, and medical and dental history as it has already been described (. Figs.  1.12 and 1.13). Findings of the clinical examination (objective examination) are noted as objective signals and symptoms divided in extraand intraoral diagnostic findings (. Fig. 1.14). Recordings of dental and periodontal findings are best registered on charts, which graphically provide a number of information in a clearly arranged manner (. Fig.  1.15). Furthermore, these records become indispensable in the communication with third parties or a fellow colleague [57, 66]. The condition of every tooth, restorations, defects, caries, and soft and hard tissues are registered. A detailed record of nature, place, and even the size of restorations should be performed [16].  

 

 

 

Tip

No matter how busy you are in a day, take your time for documentation; it is worth the effort and can save you money and trouble in the event of a legal dispute.

During shared decision-making, different treatment options, including their benefits and potential risks, are discussed with the patient. Ultimately both the patient and the doctor come to a therapeutic solution both parties support and agree upon. It might be useful to briefly note all options, including those services the clinician cannot provide himself, since it may happen that patients regret their decision. Therefore, it will be helpful to refer to the notes of the decision-­ making process. It is highly recommended to explain and to describe treatment options thoroughly, registering the teeth, procedure, and materials involved. Risk communication includes the discussion of limitations and potential harms of every treatment option, based on the best available evidence and more importantly in a clear and nontechnical language (. Fig.  1.16) [3]. The best way to document the result of a shared decision-making is an informed consent signed by all parties involved. The patient has the right to receive clear, simple, and comprehensible information about diagnoses and possible therapeutic actions. In a consumer point of view, the offering and presentation of the treatment should be correct, clear, precise, ostensive, and in patient’s language, informing the characteristics, quality, quantity, composition, price, and guarantee, as the risks that they might present to his health and safety [49].  

>> During shared decision-making, different treatment options, including their benefits and potential risks, are discussed with the patient. Ultimately both the patient and the doctor come to a therapeutic solution both parties support and agree upon.

>> The patient has the right to receive clear, simple, and comprehensible information about diagnoses and possible therapeutic actions. In a consumer point of view, the offering and presentation of the treatment should be correct, clear, precise, ostensive, and in patient’s language, informing the characteristics, quality, quantity, composition, price, and guarantee, as the risks that they might present to his health and safety.

Apart from risk communication, costs and length of the treatment should be transparent and overtly discussed. As mentioned before, it is the patients’ inherent right to decide what treatment they prefer and, perhaps more importantly, which option is unwanted. Medical laypersons often dread to take decisions because they feel overstrained, helpless, and uneasy to be responsible for their decision. It is therefore the clinicians’ duty to enable a patient to take part in the decision-­ making process according to their medical literacy. In conclusion, patients do not have to become professionals in order to take a self-determined therapy options, but doctors need to learn how to transfer the existing evidence into easily consumable facts and how to carve out the patients’ very own interests. Tip

Risk communication seems to be unpleasant, especially for inexperienced dentists. Patients, however, have a right to learn about the risks involved in a particular treatment option and usually appreciate clear-cut information.

Every treatment is documented separately and in detail in the patients’ file including date, which tooth surface has been treated and what procedure has been carried out mentioning all materials (. Fig.  1.17). Changes of the initial treatment plan, nonattendance, and new information should be recorded. Whenever needed the patients’ signature may be added as a sign of mutual agreement [3]. Oral health records are legal documents. They might become key component of a legal dispute. Hence, clarity and completeness in documentation are quintessential [66]. Erasing text passages is not allowed and impossible in electronic patient files. Mistakes are marked as such and corrections should follow below, dated and signed [40, 66]. In many ethical proceeding of the Dental Councils, dentists did not do technical mistakes but failed to adequately state risks and alternatives to the proposed treatment [3]. . Figures 1.12 and 1.17 display an example of clinical charts following the guidelines of the Dental Federal Council. In the course of progressive digitization and networking, various documentation and accounting software have become available for dental offices and universities. While handwritten documents may have their veracity proven by graphological methods, and a photography finds its proof on the negative film, a digital document may lack proof [3].  

 

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34

C. R. G. Torres et al.

DENTIST'S NAME DENTIST'S SPECIALITY REGISTRATION NUMBER Complete address

1 Name: Date of birth: / / Marital status: Phone (com): Home address: Business address: Spouse name: Recommended by: Last dentist: Legal guardian: Name: Social Security:

ID: Gender: ( )M ( )F City of birth: Profession: Cell number:

Social security: Nationality: Phone (res): E-mail:

ID: Insurance company:

Social security: Insurance number: Last consult: / ID:

/

Marital Status:

ANAMNESIS Chief Complain: History of the present illness:

MEDICAL HISTORY YES

Are you under any medical treatment? What? Doctor's name: Taking any medication? What? Have taken or is taking: Blood thinner? Anticonvulsants? Tranquilizer? Antihistamines? Analgesics? Corticosteroids? Have you received dental anesthesia? Have you been submitted to a surgery? What? Have you been hospitalized? Why? Gained or lost weight quickly recently? Why? Do you practice sports or physical activity? What? How often? Since when? Do you drink alcoholic beverages? What? How often? Since when? Do you smoke? Did you receive chemotherapy or radiotherapy? Why? BREATHING PROBLEMS Do (Did) you have any of the following diseases? Pneumonia? Sinusitis? Rhinitis? Bronchitis? Asthma? Hemoptysis (spit blood)? Pneumoconiosis (Disease caused by inhaling dust)? Lung Emphysema? Other breathing problem? What? Cough for more than 3 weeks?

NO DON’T KNOW

( ( ( ( ( (

( ( ( ( ( ( ( ( ( ( ( ( ( (

( ( ( ( ( ( ( (

( ( ( ( ( ( ( (

( ( ( ( ( ( ( (

( ( ( ( ( ( ( (

( ( ( ( ( ( ( (

( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( (

( ( ( ( ( (

( ( ( ( ( ( ( ( ( ( ( (

( ( ( ( ( ( ( ( (

( ( ( ( ( ( ( ( (

( ( ( ( ( ( ( ( (

( ( ( ( ( ( ( ( (

( ( ( ( ( ( ( ( (

( ( ( ( ( ( ( ( (

( ( ( ( ( (

CARDIOVASCULAR PROBLEMS Do (Did) you have any of the following problems? Cardiac problems? Pacemaker? Chest pain? Cardiac transplant Shortness of breath or easily tired? How many pillows do you use? Cardiac valve problems? Heart murmur? Hypotension? (Low blood pressure) Hypertension? (High blood pressure) Bleeds much when gets cut or extracts a tooth? Varicose veins? Infarction (Heart attack)? Cerebrovascular accident? Feet or legs swelling? Heart problems? What? ALLERGIES Are you allergic or had a reaction to: Dental anesthesia? Penicillin or other antibiotic? Sulfamethoxazole (Bactrim)? Aspirin? Dipyrone? Metals? Latex (rubber)? Iodine? Animals? Food? Resins? Oxygenated water? Other ? What ? KIDNEY PROBLEMS Do (Did) you have any of the following problems? Nephritis? Kidney failure? Hemodialysis? Polyuria? (large amounts of urine) Pollakiuria? (extraordinary daytime urinary frequency) Dysuria? (Painful urination) Cystitis (inflammation of the bladder)? Any other kidney problem? What?

..      Fig. 1.12  Template of clinical chart (identification data, anamnesis, medical history)

YES

NO

DON’T KNOW

( ( ( ( (

( ( ( ( (

( ( ( ( (

( ( ( ( (

( ( ( ( (

( ( ( ( (

( ( ( ( ( ( ( ( ( (

( ( ( ( ( ( ( ( ( (

( ( ( ( ( ( ( ( ( (

( ( ( ( ( ( ( ( ( (

( ( ( ( ( ( ( ( ( (

( ( ( ( ( ( ( ( ( (

( ( ( ( ( ( ( ( ( ( ( (

( ( ( ( ( ( ( ( ( ( ( (

( ( ( ( ( ( ( ( ( ( ( (

( ( ( ( ( ( ( ( ( ( ( (

( ( ( ( ( ( ( ( ( ( ( (

( ( ( ( ( ( ( ( ( ( ( (

( ( ( ( ( ( ( (

( ( ( ( ( ( ( (

( ( ( ( ( ( ( (

( ( ( ( ( ( ( (

( ( ( ( ( ( ( (

( ( ( ( ( ( ( (

1

35 Diagnosis and Treatment Planning

YES NO DON’T KNOW ONLY WOMEN BLOOD PROBLEMS Are you pregnant? How far? Do (Did) you have anemia? ( ( ( ( ( ( ( ( ( ( ( ( Are you breastfeeding? Do (Did) you have Leukemia? ( ( ( ( ( ( Are you taking birth control pills? Do you have hemophilia? ( ( ( ( ( ( Are you under hormone replacement therapy? Did you receive blood transfusion? ( ( ( ( ( ( Is it regular your menstrual cycle? Why? Do (Did) you have hemorrhage? HEPATIC PROBLEMS ( ( ( ( ( ( Where? Do (Did) you have cirrhosis? ( ( ( ( ( ( Why? Do (Did) you have other hepatic problem? Do (Did) you have any blood problem? What? What? JOINT/BONE PROBLEMS Did you fracture any bone? ( ( ( ( ( ( SALIVARY PROBLEM Where? Do you have excessive production of saliva? ( ( ( ( ( ( Did you have any facial trauma? Do you have xerostomia? (little or no saliva) Do (Did) you have arthritis? ( ( ( ( ( ( Did you have salivary stone? Do (Did) you have arthrosis? ( ( ( ( ( ( NEUROLOGIC PROBLEMS Do (Did) you have rheumatism? ( ( ( ( ( ( Do you have frequent fainting? Do (Did) you have rheumatic fever? ( ( ( ( ( ( Do you have frequent headache? Do (Did) you have osteoporosis? ( ( ( ( ( ( Do (Did) you have facial neuralgia? Do (Did) you have any bone calcification problem? ( ( ( ( ( ( Did you have convulsions? Do (Did) you have join problems? ( ( ( ( ( ( Do you have epilepsy? Do (Did) you have other joint or bone problem? ( ( ( ( ( ( Do (Did) you receive psychiatric treatments? What? Since when? TRANSMISSIBLE DISEASES Why? Do (Did) you have gonorrhea? ( ( ( ( ( ( Are you stressed? Do (Did) you have syphilis? ( ( ( ( ( ( Do (Did) you have any other neurologic problem? ( ( ( ( ( ( Do you have AIDS? What? ( ( ( ( ( ( Do (Did) you have hepatitis? GASTROINTESTINAL PROBLEM ( ( ( ( ( ( Do (Did) you have tuberculosis? Do (Did) you have gastritis? Do (Did) you have any childhood disease? ( ( ( ( ( ( Do (Did) you have stomach ulcers? Other? What? Did you vomit blood? ( ( ( ( ( ( Do (Did) you have any other gastrointestinal problem? ENDOCRINE DISORDERS (hormonal disorders) What? ( ( ( ( ( ( Do you have polyphagia (excessive hunger)? Do you have polydipsia (excessive thirst)? ( ( ( ( ( ( FAMILY HISTORY Do you have diabetes? ( ( ( ( ( ( Is there any one sick in your family? ( ( ( ( ( ( Do you have hypothyroidism? What disease? ( ( ( ( ( ( Do you have hyperthyroidism? In your family, was there any case of: ( ( ( ( ( ( Do you have Hyperparathyroidism? Cancer? ( ( ( ( ( ( Do (Did) you have any other endocrine problem? - Diabetes? What? - Infarct? OPHTHALMIC PROBLEMS - Hypertension? ( ( ( ( ( ( Do (Did) you have glaucoma? - Renal Problem? Did any doctor recommend the use of antibiotic before the dental treatment? Did you have any other health problem not mentioned in this questionnaire? What?

DENTAL HISTORY

YES

NO DON’T KNOW

YES

( ( ( (

NO

( ( ( (

( ( ( (

DON’T KNOW

( ( ( (

( ( ( (

( ( ( ( ( ( ( ( ( ( ( (

( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( (

( ( ( ( ( (

( ( ( ( ( (

( ( ( ( ( (

( ( ( ( ( (

..      Fig. 1.13  Template of clinical chart (medical and dental history)

( ( ( ( ( (

( ( ( ( ( ( ( ( ( ( ( ( ( ( ( (

( ( ( (

( ( ( (

( ( ( (

( ( ( (

( ( ( (

( ( ( ( ( ( ( ( ( ( ( ( (

YES

( ( ( ( ( ( (

( ( ( ( ( ( (

( ( ( ( ( ( (

( ( ( ( ( ( (

( ( ( ( ( ( (

NO DON’T KNOW

( ( ( ( ( Did you have cold sores in the lips? Did you receive professional oral hygiene instructions? ( ( ( ( ( ( ( ( ( ( ( Have you lived -erg a place without water treatment? How many times do you brush your teeth a day? ( ( ( ( ( ( ( ( ( ( ( Do you grind or ciench your teeth (day or night)? Do you use dental floss? ( ( ( ( ( Do you chew in just one side? How often? ( ( ( ( ( ( Why? Does your gum bleed? ( ( ( ( ( ( ( ( ( ( ( Do you hear a clicking when open your mouth? Are your teeth sensitive to temperature changes? ( ( ( ( ( ( ( ( ( ( ( Do you feel pain in the ear, head, face or neck? Are your teeth sensitive to sweets? ( ( ( ( ( ( ( ( ( ( ( Do you have difficulty to open your mouth? Are your teeth sensitive when biting? ( ( ( ( ( ( ( ( ( ( ( When waking up, feel face muscles and/or teeth in pain? Are you feeling any pain on teeth? ( ( ( ( ( Did you have any problem with dental treatment? Where? What? Do you have the habit of nail biting and thumb sucking? ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( Do you have mouth sores Do you have the habit of biting objects? ( ( ( ( ( ( ( ( ( ( ( Do you practice any sports Do you often bite tongue, lips or cheeks? ( ( ( ( ( ( ( ( ( ( ( Did you have any impact on the mouth? Do you breathe through the mouth? ( ( ( ( ( ( ( ( ( ( ( Do you feel food deposit between teeth? Do you drink coffee/soda during the day? ( ( ( ( ( ( ( ( ( ( ( Did you have any other oral problem? Do you frequently have mouth sores? ( ( ( ( ( ( What? Do you have any tooth mobility? ( ( ( ( ( ( Did you receive orthodontic treatment? ( ( ( ( ( ( How often do you visit the dentist? Are you satisfied with your oral aesthetics? ( ( ( ( ( ( Did you have any mouth infection? I certify that every answer, including personal information, above written is true. I compromise to inform any change in my current health status. , , of 20 Patient's/legal guardian's signature

( ( ( (

( ( ( ( ( ( ( ( ( ( ( ( ( (

36

1

C. R. G. Torres et al.

CLINICAL EXAM General aspect: Vital signs: Pulse:

bpm (

/

/

);

( (

; Glycemic index: Blood pressure:

EXTRAORAL Lymph nodes: Muscle palpation: Lesions:

/ /

/ /

); );

( (

/ /

/ /

); );

( (

/ /

/ /

Swelling and asymmetry: TMJ palpation: Other:

INTRAORAL Occlusion evaluation ; Overbite: Static evaluation: Angle classification: ; Tooth migration or leaning? Tooth extrusions? Anterior open bite? Loss of molar support?

Overjet: Loss of vertical dimension?

; TMJ snaps? Functional evaluation: Relation between CR and CO: ; Right lateral: ; Left lateral: Disocclusion guidance: Anterior: ; Abfraction? Wearing facet from attrition? ; Protrusion interference? Non-working side interference? ; Deviation when opening? Amount of mouth opening: Soft tissues evaluation Lips: Dorsum of the tongue: Palate:

; cheeks: ; Ventral surface of the tongue: ; Tonsils:

; Vestibule: ; Floor of the mouth:

Teeth evaluation DENTAL CHART IN

1.8.

1.7.

4.8.

4.7.

AM

AM

CE

CE

COM

1.6.

1.5.

1.4.

4.6.

4.5. AM

= Lesion (carious/non carious)

X

4.4.

1.3.

/

COM

COM

COM

AR

FPD

FPD

FPD

COM

AM

1.2.

1.1.

2.1.

2.2.

2.3.

2.4.

2.5.

2.6.

2.7.

4.3.

4.2. 4.1.

3.1.

DT

COM COM

COM

AM

/

3.2.

3.3.

2.8.

3.4.

3.5.

3.6.

3.7.

3.8.

GIC

CM

CE

FSP

FSI

= Amalgam

MC

= Metal-ceramic

= Deficient restoration

COM

= Composite resin

FPD

= Fixed partial denture

= Satisfactory restoration

GIC

= Glass ionomer cement

RPD

= Removable partial denture

= Absent tooth

CM

= Cast metal

FSI

= Fissure sealant is indicated

= Endodontic treatment is necessary

CE

= Ceramic

FSP

= Fissure sealant is present

= Endodontic treatment is present

AR

= Acrylic resin

DT

= Darkened tooth

= Implant

TR

= Temporary restoration

..      Fig. 1.14  Template of clinical chart (clinical examination – extraoral and intraoral)

WSL

= White spot lesion

); );

37 Diagnosis and Treatment Planning

Periodontal evaluation Date: Probe Depth GM to CEJ Attachment Loss

/

/

18

17

16

15

14

13

12

11

21

22

23

24

25

26

27

28

18

17

16

15

14

13

12

11

21

22

23

24

25

26

27

28

48

47

46

45

44

43

42

41

31

32

33

34

35

36

37

38

48

47

46

45

44

43

42

41

31

32

33

34

35

36

37

38

B U C C A L L I N G U A L

Probe Depth GM to CEJ Attachment Loss

Probe Depth GM to CEJ Attachment Loss L I N G U A L B U C C A L

Probe Depth GM to CEJ Attachment Loss

Gingival bleeding index 1.8. 1.7. 1.6. 1.5. 1.4. 1.3. 1.2. 1.1. 2.1. 2.2. 2.3. 2.4. 2.5. 2.6. 2.7. 2.8.

/

/

GBI: 4.8. 4.7. 4.6. 4.5. 4.4. 4.3. 4.2. 4.1. 3.1. 3.2. 3.3. 3.4. 3.5. 3.6. 3.7. 3.8. 1.8. 1.7. 1.6. 1.5. 1.4. 1.3. 1.2. 1.1. 2.1. 2.2. 2.3. 2.4. 2.5. 2.6. 2.7. 2.8.

/

/

GBI: 4.8. 4.7. 4.6. 4.5. 4.4. 4.3. 4.2. 4.1. 3.1. 3.2. 3.3. 3.4. 3.5. 3.6. 3.7. 3.8.

O’Leary plaque index 1.8. 1.7. 1.6. 1.5. 1.4. 1.3. 1.2. 1.1. 2.1. 2.2. 2.3. 2.4. 2.5. 2.6. 2.7. 2.8.

/

/

PI: 4.8. 4.7. 4.6. 4.5. 4.4. 4.3. 4.2. 4.1. 3.1. 3.2. 3.3. 3.4. 3.5. 3.6. 3.7. 3.8. 1.8. 1.7. 1.6. 1.5. 1.4. 1.3. 1.2. 1.1. 2.1. 2.2. 2.3. 2.4. 2.5. 2.6. 2.7. 2.8.

/

/

PI: 4.8. 4.7. 4.6. 4.5. 4.4. 4.3. 4.2. 4.1. 3.1. 3.2. 3.3. 3.4. 3.5. 3.6. 3.7. 3.8.

..      Fig. 1.15  Template of clinical chart (clinical examination – periodontal evaluation, bleeding index, plaque index)

1

38

C. R. G. Torres et al.

TREATMENT PLAN

1

Problems List

Treatment option

1

17 – Carious lesion OL (2 surfaces)

2

14 – Deficient restoration OD (2 surfaces)

3

13 and 33 — Pulpal necrosis

4

11, 21 and 41 – Defective restorations (4 surfaces)

5

22 – Defective total crown

6

26 – Defective MODV restoration

7

46 – Carious MOD lesion (3 surfaces)

8

45 – Defective MO restoration

9

43 – Darkened tooth

10

46, 44 and 32 – Non carious cervical lesion (3 surfaces)

a)Amalgam restoration b)Composite restoration c) ---------a)Amalgam restoration b)Composite restoration c) ---------a)Endodontic treat. + Compos. b) ---------c) ---------a)Composite restoration b) ---------c) ---------a)Metal free full crown b)Metal ceramic crown c) Metallic-plastic crown a)lndirect ceramic rest. b)Amal. rest.+ comp. veneer c)Composite restoration a)Amalgam restoration b)Composite restoration c) ---------a)Amalgam restoration b)Composite restoration c) ---------a)lnternal bleaching b)lndirect veneer b)Direct veneer a)Composite restoration b)GlC restoration c)Amalgam restoration

Advantage/ Disadvantage > Durability > Aesthetic ---------> Durability < Durability ---------Only option ------------------Only option ------------------> Aesthetic > Resistence < Aesthetic >Aesthetic, >Resist.

< Aesthetic < Resistence > Durability > Aesthetics ---------> Durability > Aesthetic ---------Less Invasive Dental wearing Dental wearing > Aesthetic wearing

TOTAL Treatment sequence:

Fees

Time

100.00 200.00 ---------100.00 200.00 ---------800.00 ------------------400.00 ------------------1000.00 800.00 300.00 1000.00 250.00 500.00 150.00 300.00 ---------100.00 200.00 ---------200.00

1h 1h ---1h 1h ---4h ------3h ------3h 3h 3h

400.00 200.00 300.00 150.00 150,00 3400.00

2h 1h 1h 1h 1h ---1h 1h ---4h 3h 1h 1h 1h 1 21h

Patient's option X

X

X

X

X

X

X

X X

X

3, 1, 7, 6, 2, 4, 8, 10, 5, 9 INFORMED CONSENT DECLARATION

I state that after being informed about of the purposes, risks, costs and treatment alternatives, according to what is presented above. I agree, accept and authorize the treatment, and declare to follow the professional instructions and pay the costs that are mentioned on the presented budget.

,

Patient's or Legal Guardian signature ..      Fig. 1.16  Template of clinical chart (treatment plan, informed consent)

,

of 20

Dentist's signature

39 Diagnosis and Treatment Planning

..      Fig. 1.17  Template of clinical chart (records of procedures and relevant information about the dental visit)

1

40

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C. R. G. Torres et al.

Other than that, current legislation in some countries still oblige dental services that patient documents must be handwritten or have a “physical existence” [3]. However, as this new tendency seems to be irreversible, it has been calling researchers and legislators to change the system to legally recognize electronic documentation, without the possibility of adulteration or violation of medical confidentiality [3]. The Dental Council gave dentist the choice between handwritten or computerized documentation [3]. Information and requirements have to be supplied, inside a pattern of authenticity regardless of the documentation mode [3]. In recent years, many countries create a system of digital certification, designated to guarantee the authenticity, the integrity, and the juridical validation of the documents in electronic form [3]. This is a method to recognize the authenticity of a digital document (Digital Certificate) similar to an “authentication” by a notary. After the identification and the registration of the user by an official authority, they receive a “key” (called token or a smart card), a type of identity card. Technically, an external device that is connected to the computer liberates, through a pin code, a text that is incorporated into the document that needs to be authenticated. A type of an “electronic stamp” that declares its authenticity. This signature is achieved or printed together along with the document and can be sent with the document to the receiver. However, if for some reason there is an alteration of at least one letter, the certificate is excluded, disappearing the authentication registration and canceling the recognition. On this way, the document is protected against adulterations [3]. However, the contract of service, authorization for the treatment (in case of minors or incapable), anamnesis, and any further documents that may need the signature in paper still need to be printed, unless patients or their legal representatives also have their digital signature [3]. Conclusion Patients seeking for dental treatment present actual complaints and have their own theories of a disease and personal preferences regarding treatment options. It is the clinician’s duty to uncover this information and to develop a personalized treatment plan in accordance with the patient. The patient has to be an equal partner in this process, even though not being a dental professional. Therefore, dentists need to avoid technical language and always should be aware of anxieties and concerns. Active listening is a basic communication skill that encourages people to talk and keep them interactive. Identification of the chief complaints and knowing a patient’s medical attitude and expectation build a reliable and solid fundament for an intact doctor-patient relationship. Empathy and respecting patients’ autonomy are simple to adopt prerequisites to build up an equal partnership. They are also an essential precondition for shared decision-­making. Apart from the interpersonal level, a sound examination allows proposal of a most probable diagnosis, which in turn is the fundament for the treatment plan. Dentists need to accept that diagnoses may be false, and they need to explain that to their patients giving likelihood ratios at the best. It is advisable to follow a certain systematic during the clinical

examination. After the interview, it is best to start with the extraoral and then proceed with the intraoral assessment. Dental findings are recorded separately from periodontal and endodontic findings using hard copies or digital files. Many patients are unsatisfied with their esthetic appearance and possibly state these concerns during the medical interview. Analysis of dental, periodontal, and facial esthetics may round off a comprehensive clinical examination. Based on clinical findings and in conjunction with the patient’s complaints, a treatment plan is developed. In a modern doctor-patient relationship, an empowered patient takes a self-responsible informed choice after discussing advantages and risks of potential options. Clinicians need to be up-­ to-­date with the best available evidence, in order to provide actual information needed to take a treatment decision. Sometimes no treatment can be an option as well and displays a deliberate choice as well. Shared decision-making is opposed to a paternalistic model where doctors dictate patients what choice is best for them. In many countries, shared decision-making is made mandatory by law. After shared decision-making, patients are informed better, have more control, and stick to their therapy of choice. Implementation of the treatment plan is sequenced in different phases, systemic, urgency, control, corrective, and maintenance phase. Each phase helps the patient to establish oral health and improve or maintain masticatory function or dental esthetics. Ultimately, every intervention should improve oral health-related quality of life.

References 1. Alam M, Bastakoti B. Therapeutic guidelines: antibiotic. Version 15. Aust Prescr. Melbourne: Therapeutic Guidelines Limited; 2015; 38:137. https://doi.org/10.18773/austprescr.2015.049. 2. Allen EP.  Surgical crown lengthening for function and esthetics. Dent Clin N Am. 1993;37:163–79. 3. Almeida C, Zimmermann R, Cerveira J, Julivaldo F. Prontuário odontológico – Uma orientação para o cumprimento da exigência contida no inciso VIII do art. 5° do Código de Ética Odontológica. Cons Fed Odontol Rio de Janeiro; 2004. 4. Andrade E. Terapêutica medicamentosa em odontologia. São Paulo: Artes Médicas; 2002. 5. Asa’ad F. Shared decision-making (SDM) in dentistry: a concise narrative review. J Eval Clin Pract. 2019.;jep.13129; https://doi. org/10.1111/jep.13129. 6. Attin T, Wegehaupt FJ.  Impact of erosive conditions on tooth-­ colored restorative materials. Dent Mater. 2014;30:43–9. https://doi. org/10.1016/j.dental.2013.07.017. 7. Baratieri LN, Monteiro Junior S, Andrada MA, Ritter AV. Odontologia Restauradora: Fundamentos e Possibilidades. São Paulo: Santos; 2001. 8. Barbe A, Heinzler A, Derman S, Hellmich M, Timmermann L, Noack M.  Hyposalivation and xerostomia among Parkinson’s disease patients and its impact on quality of life. Oral Dis. 2017;23:464–70. https://doi.org/10.1111/odi.12622. 9. Barbe AG.  Medication-induced xerostomia and hyposalivation in the elderly: culprits, complications, and management. Drugs Aging. 2018;35:877–85. https://doi.org/10.1007/s40266-018-­0588-5. 10. Barbe AG, Bock N, Derman SHM, Felsch M, Timmermann L, Noack MJ.  Self-assessment of oral health, dental health care and oral health-related quality of life among Parkinson’s disease patients. Gerodontology. 2017;34:135–43. https://doi.org/10.1111/ger.12237.

41 Diagnosis and Treatment Planning

11. Beauchamp TL, Childress JF. Principles of biomedical ethics. 7th ed. Oxford: Oxford University Press; 2013. 12. Berkey DB, Berg RG, Ettinger RL, Mersel A, Mann J. The old-old dental patient: the challenge of clinical decision-making. J Am Dent Assoc. 1996;127:321–32. 13. Brandão RCB, Brandão LBC. Finishing procedures in orthodontics: dental dimensions and proportions (microesthetics). Dental Press J Orthod. 2013;18:147–74. https://doi.org/10.1590/S2176-­94512013000500006. 14. Brännström M. The hydrodynamic theory of dentinal pain: sensation in preparations, caries, and the dentinal crack syndrome. J Endod. 1986;12:453–7. https://doi.org/10.1016/S0099-­2399(86)80198-4. 15. Brantley CF, Bader JD, Shugars DA, Nesbit SP.  Does the cycle of rerestoration lead to larger restorations? J Am Dent Assoc. 1995;126:1407–13. 16. Bullen CME, Sierra E. Odontograma para tratamientos preventives y conservadores en restauradora dental. Rev Fola/Oral. 1997;3 17. Busato ALS. Dentística: Filosofia, conceitos e prática clínica. 1st ed. São Paulo: Artes Médicas; 2005. 18. Conceição M, Marocchio L, Fagundes R. Técnica de Sialometria para uso na prática clínica diária. Available at: http://www.­halitofresco.­ com.­b r/pdf/tecnica-de-sialometria-para-uso-na-pratica- ­c linica-­ diaria.­pdf. 19. Congiusta MA.  No differences in longevity of direct and indirect composite restorations. Evid Based Dent. 2017;18:46. https://doi. org/10.1038/sj.ebd.6401237. 20. Dablanca-Blanco AB, Blanco-Carrión J, Martín-Biedma B, Varela-­ Patiño P, Bello-Castro A, Castelo-Baz P. Management of large class II lesions in molars: how to restore and when to perform surgical crown lengthening? Restor Dent Endod. 2017;42:240. https://doi. org/10.5395/rde.2017.42.3.240. 21. Drancourt N, Roger-Leroi V, Martignon S, Jablonski-Momeni A, Pitts N, Doméjean S. Carious lesion activity assessment in clinical practice: a systematic review. Clin Oral Investig. 2019;23:1513–24. https://doi.org/10.1007/s00784-019-02839-7. 22. Fasbinder DJ. Treatment planner’s toolkit. Gen Dent. 47:35–9. 23. Fehrenbach MJ, Weiner J. Saunders review of dental hygiene. St. Louis: Saunders; 2008. 24. Genovese WJ. Metodologia do exame clínico em odontologia. 2nd ed. São Paulo: Pancast; 1992. 25. Gillam DG, Yusuf H. Brief motivational interviewing in dental practice. Dent J. 2019;7:51. https://doi.org/10.3390/dj7020051. 26. Gimenez T, Piovesan C, Braga MM, Raggio DP, Deery C, Ricketts DN, et al. Visual inspection for caries detection. J Dent Res. 2015;94:895– 904. https://doi.org/10.1177/0022034515586763. 27. Goldstein GR. The longevity of direct and indirect posterior restorations is uncertain and may be affected by a number of dentist-, patient-, and material-related factors. J Evid Based Dent Pract. 2010;10:30–1. https://doi.org/10.1016/j.jebdp.2009.11.015. 28. González-Cabezas C, Hara AT, Hefferren J, Lippert F. Abrasivity testing of dentifrices  – challenges and current state of the art; 2013. p. 100–7. https://doi.org/10.1159/000350476. 29. Hänsel Petersson G, Åkerman S, Isberg P-E, Ericson D. Comparison of risk assessment based on clinical judgement and Cariogram in addition to patient perceived treatment need. BMC Oral Health. 2017;17:13. https://doi.org/10.1186/s12903-016-0238-4. 30. Haralur SB, Alqahtani AS, AlMazni MS, Alqahtani MK. Association of non-carious cervical lesions with oral hygiene habits and dynamic occlusal parameters. Diagnostics. 2019;9:43. https://doi. org/10.3390/diagnostics9020043. 31. Heaven TJ, Firestone AR, Weems RA. The effect of multiple examinations on the diagnosis of approximal caries and the restoration of approximal surfaces. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 1999;87:386–91. 32. Hempton TJ, Dominici JT.  Contemporary crown-lengthening therapy: a review. J Am Dent Assoc. 2010;141:647–55. 33. Imfeld T.  Dental erosion. Definition, classification and links. Eur J Oral Sci. 1996;104:151–5.

34. Kassebaum NJ, Bernabé E, Dahiya M, Bhandari B, Murray CJL, Marcenes W. Global burden of untreated caries. J Dent Res. 2015;94:650– 8. https://doi.org/10.1177/0022034515573272. 35. Kidd EAM, O’Hara JW. The caries status of occlusal amalgam restorations with marginal defects. J Dent Res. 1990;69:1275–7. https://doi. org/10.1177/00220345900690061001. 36. Klein F, Keller AK, Staehle HJ, Dörfer CE. Proximal contact formation with different restorative materials and techniques. Am J Dent. 2002;15:232–5. 37. Kupke J, Wicht MJ, Stützer H, Derman SHM, Lichtenstein NV, Noack MJ. Does the use of a visualised decision board by undergraduate students during shared decision-making enhance patients’ knowledge and satisfaction? – A randomised controlled trial. Eur J Dent Educ. 2013;17:19–25. https://doi.org/10.1111/eje.12002. 38. Lang F, Floyd MR, Beine KL. Clues to patients’ explanations and concerns about their illnesses. A call for active listening. Arch Fam Med. 2000;9:222–7. 39. Lombardi RE. The principles of visual perception and their clinical  application to denture esthetics. J Prosthet Dent. 1973;29: 358–82. 40. Machen D. Legal aspects of orthodontic practice: risk management concepts. Current concepts in orthodontic informed consent. Am J Orthod Dentofacial Orthop. 1989;96:88–9. 41. Magne P, Belser U. Restaurações adesivas de porcelana na dentição anterior: Uma abordagem biomimética. São Paulo: Quintessence; 2003. 42. Mamoun J, Napoletano D. Cracked tooth diagnosis and treatment: an alternative paradigm. Eur J Dent. 2015;9:293. https://doi. org/10.4103/1305-7456.156840. 43. Marinho VCC. Prática odontológica baseada em evidência. Sua aplicação na promoção de saúde bucal. In: Buischi YP, editor. Promoção saúde bucal na clínica odontológica. São Paulo: Artes Médicas; 2000. p. 339–59. 44. Mergulhão V, de Mendonça L, de Albuquerque M, Braz R. Fracture resistance of endodontically treated maxillary premolars restored with different methods. Oper Dent. 2019;44:E1–11. https://doi. org/10.2341/17-262-L. 45. Miller EL, Bodden WR, Jamison HC. A study of the relationship of the dental midline to the facial median line. J Prosthet Dent. 1979;41: 657–60. 46. Milosevic A.  Direct placement composite: the treatment modality of choice to restore the worn or eroded dentition in primary dental care. Prim Dent J. 2016;5:25–9. 47. Mjör IA, Shen C, Eliasson ST, Richter S. Placement and replacement of restorations in general dental practice in Iceland. Oper Dent. 27:117–23. 48. Mulic A, Svendsen G, Kopperud SE. A retrospective clinical study on the longevity of posterior Class II cast gold inlays/onlays. J Dent. 2018;70:46–50. https://doi.org/10.1016/j.jdent.2017.12.010. 49. Paranhos LR, Salazar M, Ramos AL, Siqueira DF. Orientações legais aos cirurgiões-dentistas. Rev Odontol. 2007;15:8. 50. Pashley DH. How can sensitive dentine become hypersensitive and can it be reversed? J Dent. 2013;41:S49–55. https://doi.org/10.1016/ S0300-5712(13)70006-X. 51. Petersson GH, Twetman S.  Tobacco use and caries increment in young adults: a prospective observational study. BMC Res Notes. 2019;12:218. https://doi.org/10.1186/s13104-019-4253-9. 52. Pinto VG.  Saúde bucal coletiva. 4th ed. São Paulo: Editora Santos; 2000. 53. Priyanka K. Impact of alcohol dependency on oral health – a cross-­ sectional comparative study. J Clin Diagn Res. 2017;11:ZC43–6. https://doi.org/10.7860/JCDR/2017/26380.10058. 54. Roberson TM, Heymann H, Swift EJ. Sturdevant’s art and science of operative dentistry. 5th ed. St. Louis: Mosby; 2006. 55. Roberson TM, Heymann H, Swift EJ, Sturdevant CM. Sturdevant’s art and science of operative dentistry. Orlando: Mosby/Elsevier; 2006.

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43

Ergonomics Principles Applied to the Dental Clinic Karen Cristina Kazue Yui, Cristiani Siqueira Barbosa Lencioni, Eliel Soares Orenha, and Carlos Rocha Gomes Torres 2.1

Introduction – 44

2.2

Ergonomics in Dentistry – 44

2.2.1 2.2.2 2.2.3 2.2.4 2.2.5 2.2.6 2.2.7 2.2.8 2.2.9 2.2.10 2.2.11 2.2.12

 orking Posture – 45 W Positioning of the Delivery Unit and Dental Chair – 50 Positioning of the Patients on the Chair – 53 Positioning of the Patient’s Head – 54 Positioning the Operating Field in Relation to the Dentist – 55 Positioning of the Operating Field in Relation to the Assistant – 56 The Use of Overhead Chair Light – 57 Vision of the Teeth to Be Treated – 58 Types of Movements During the Dental Treatment – 58 Ways to Grasp the Hand Instruments – 59 Rest Places – 61 Work Environmental Conditions – 63

2.3

Work-Related Musculoskeletal Disorders – 65

2.3.1 2.3.2

 ccupational Diseases Epidemiology – 67 O WMSD Prevention – 68

2.4

Exercises to Prevent Osteomuscular Problems – 69

2.5

 urrent Panorama of Dental Ergonomic: Challenges, C Proposals, and Goals – 74 References – 75

© Springer Nature Switzerland AG 2020 C. R. G. Torres (ed.), Modern Operative Dentistry, Textbooks in Contemporary Dentistry, https://doi.org/10.1007/978-3-030-31772-0_2

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Learning Objectives

2

The learning objectives of this chapter are related to the following topics: 55 The principals of ergonomics in dentistry 55 How to ergonomically seat during the dental treatment 55 How to properly position the patient in the chair in order to have the operating field facing the operator and assistant 55 How to grasp the instruments and rest the fingers in the oral environment, in order to have the full control of the hand during treatment 55 How to deal with the work environmental condition in order to protect the dental team health 55 How to prevent the most common work-related musculoskeletal disorders in dentistry

2.1

Introduction

We, human beings, are provided of a force that drives us to a continuous search of the knowledge of ourselves and to better adapt to the environment in which we live, aiming to improve and ease the development of our activities, so we can reach superior levels of interaction, satisfaction, and internal and external well-being, socially and individually. This power, which at the same time drives and is driven by this search, enhances our capacity to transcend and develop; and nowadays, it has come to proportions never imagined before [29]. Throughout the last few years, we have noticed a rapid transformation in our society due to the huge quantity, availability, and transference of information. This has allowed a significant improvement at work and life conditions. Multiand transdisciplinary strategies have each day been more used to break barriers that once before hindered the acquisition, transference, and availability of knowledge. The ergonomics, by its own nature, has benefited on this context, enclosing and interconnecting the knowledge of physiology, psychology, sociology, architecture, semiotics, industrial design, anthropometry, engineering, physical therapy, anthropology, medicine, communications, and many other neighboring sciences, applied to the work and on human being activities, with the purpose to improve the adaptation of the methods, means, and environment work to men [20]. Ergonomics is the study of the adaptation of the job to men, and it has been defined as “the group of scientific knowledge about men that are needed to conceive an instrument, a machine and tools that can be used with maximum comfort, safety and efficiency” [30, 36, 64]. What has been seen on most of the professions is an adaptation of men to the job and not the inverse. However, the human being is not always capable to adapt to the job. Therefore, it can be seen that men should be the center of the attentions to elaborate projects for each job, adapting it to the human being capacity and limitations [60]. Therefore, for the ergonomic studies, it is important for us to know human being’s characteristics (physical, physiological, psychological, social aspects and age, gender, training, and motivation), characteristics of the

machine (equipment, tools, furniture, and spatial arrangement), and characteristics of the worker’s environment (temperature, noise, vibrations, light, colors, gases, etc.), besides the consequences of the job, among other things. In dentistry, as in any other health professions, this interaction between the worker, the environment, and the tool has very special characteristic. The goal of the activity is not to produce or manufacture a product or an object but to offer a service. This service is very special, because it is performed for and to a human and not for nor to an object; this fact, obviously, leads to very specific aspects, where the emotional aspects relative to the environment, the clinician, and the patient play a very fundamental role. That is why a satisfactory adaptation between the dentist and his job requires an environment that is emotionally positive and pleasant; where the feelings to go further than comfort and productivity flourish such as desire, pleasant surprises, interest, delight, admiration, satisfaction, fascination, kindness, acceptance, tolerance, proactivity, motivation, and confidence [29]. A good adaptation does not occur where there is negativity and is not pleasant and where feelings such as indignation, disdain, grief, unpleasant surprise, excessive competition, dissatisfaction, frustration, intolerance, suspicion, subordination, monotony, and fear flourish. Giving emphasis to the emotional aspects and using the knowledge on human sciences as psychology and sociology, the contemporary ergonomics aims to turn the dental service more pleasant and enjoyable, and that way demystify the image people have about the dentist, untying it from unpleasant feelings and experiences. For that, it needed a more humanized dentistry, where more empathy, affection, love, and satisfaction are noticed. Positive sensations and good feelings must be instilled on the dentistry character and on the development of the dental attention to reach those sublime goals [29].

Ergonomics is the study of the adaptation of the job to human being. What has been seen on most of the professions is an adaptation of human being to the job and not the inverse. However, the human being is not always capable to adapt to the job.

2.2

Ergonomics in Dentistry

The knowledge on dental ergonomics has advanced much on the last decades, revealing its importance for the dentist. However, we observe the non-implementation and practice of this knowledge. Some studies show that it is high the occurrence of joint, muscles and lumbar problems, and many clinicians’ diseases related to the bad posture, lack of ergonomic planning of the dental treatment unit, work ­environment, work systems, among others [27]. This has caused many of the dentists to work on a low productivity rate, without comfort and especially without the quality of

45 Ergonomics Principles Applied to the Dental Clinic

life and, in many cases, it has even drive them to abandon the career prematurely. There is no doubt the dentistry is a weary and stressful profession, which causes damage to the health, both physical and psychic [10, 37, 39, 41, 46]. Studies about the musculoskeletal disorders among dentists have been performed since the 1950s, and they are responsible for the first proposes to change their working process, including the changes on the orthostatic position to the sitting position [61]. The actual postural awkwardness at the dental work has been subject to many discussions [12]. Non-ergonomic dental workspace and awkward postures cause musculoskeletal disorders, which are common among dentists. This context is the theme for studies, especially in the ergonomics area. The posture adopted by the dentist on their tasks has changed throughout the world over the last 30 years [40]. However, the requirements of the dental practice, as the restrict visual field and adoption of awkward postures, increase the predisposition for the dentist to get musculoskeletal diseases [40, 51, 58]. Therefore, more research is needed, which can define the impacts of the muscular and nervous diseases on those clinicians, with the aim to prevent their development. With that, there will be a better quality of life and a better service [52]. There is a consensus among authors in relation to the causes of repetitive strain injuries (RSI) and work-related musculoskeletal disorders (WMSD) among the dentists and it can be highlighted: 55 Factors with organizational nature: Movement concentration on the same person, extra work hours, double shifts, accelerated work rhythm, lack of necessary pauses, pressure from the boss, and others 55 Factors with biomechanical nature: Excessive strength, intense repetitiveness of the same movement pattern, the wrong posture of the upper limbs, compression on the lower limb structures, static posture, and others 55 Factors with psychosocial nature: Excessive pressure for results, excessively tense work environment, interpersonal relation problems, excessive rigidity at the work system, and others 55 Factors of work conditions: Temperature, vibration, furniture, noise, illumination, space, tools, and others For the described factors to be considered a risk to cause RSI/ WMSD, it is important to observe their intensity, duration, and frequency [44, 45]. Among those predisposed elements, it can be pointed out the factors with organizational nature. The way in which the work is organized can cause a greater impact on the well-being of the individuals when compared to the other factors. The ergonomics applied to dentistry has the primary goal to find mechanisms to reduce the physical and mental stress on the dentist, to prevent diseases related to the dental practice, increasing the productivity  but also the quality of life [52]. The rationalization of the job can be obtained by means of organizing the clinical procedures, applying the corporate management concepts and ergonomic principles, space arrangement, and four-handed dentistry.

>> The rationalization of the job can be obtained by means of organizing the clinical procedures, applying the corporate management concepts and ergonomic principles, space arrangement, and four-handed dentistry.

International standards on the ergonomic field were elaborated aiming to promote significant improvement and to assure that the standard procedures, for a healthy and safe job, are established. The ISO 11226:2000/Cor 1:206 establishes the health limits for a static sitting job [31]. The ISO 6385:2004 presents a glossary of the main ergonomic terms, requirements and necessary procedures for the development of working systems and places [33]. In 2009, the ISO 4073 was revised and updated, and even though its first edition has been published about 40 years ago, not all clinicians apply its principles on the spatial arrangement of their work environment [15, 32]. In . Fig. 2.1, a correctly spatial arrangement of the dental office according to the ISO 4073, in which we can notice a correct division of working zones on the floor, will be described further in this chapter.  

2.2.1

Working Posture

The posture is defined by the American Academy of Orthopedics as a reactive arrangement of the body parts; the good posture is related to the balance between the support structures, the muscles, and bones, protecting themselves from aggression (direct trauma) or progressive deformity (structural changes) [1]. It is called postural work, the invisible effort that the back, shoulders, and arms muscles do in silence against gravity. When we are sitting, there is a continuous effort of the back muscles to maintain the torso erect, any other way, the body would collapse. This muscular effort generated is in disadvantage because it blocks the blood flow. To have postural comfort, uncomfortable positions for the torso, head, and arms should be avoided [5]. During the dental procedure, it should be ­permitted to alternate between the sitting and standing

..      Fig. 2.1  Dental clinical room built observing the criteria of the ISO 4073:2009 standard

2

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positions. When only one of the positions needs to be chosen, the sitting position must be preferred. Another important aspect is the interchange of the body posture to avoid prolonged muscular static tension, that will lead to fatigue. On the same way, a good balance between the body movements should be established, and the movement must be preferred against the prolonged immobility. The high precision movements, common in dentistry, should not involve a significant muscular force. The healthy posture for the dental job is sitting, also called “finger control posture” or “pianist posture.” The working position should be similar to the positions that we adopt when we are reading a book, in a way that the visual field is perpendicular to our visual axis [26]. To reach this healthy posture, three basic work positions can be used [26, 28]. 55 Active (dynamic): Static positions are only possible when the object to be seen by the dentist can face his visual axis. For example, when the dentist is adjusting a temporary crown outside the mouth, all the surfaces can be easily seen by rotating the tooth completely without having to change the visual axis. On the other hand, when the dentist makes a preparation on the buccal and lingual surfaces of the tooth 46, it is necessary to change his position and the position of the patient’s head in a way that it is possible to look in a perpendicular manner to the working field. This frequently happens during the intraoral procedures. Therefore, it is frequent the necessity to visualize different sites, which cannot be completely positioned in the direction of the visual axis of the dentist, being necessary to move to get adequate vision without excessive inclination. For that, it is necessary to have enough space under the back of the patient’s dental chair that will allow the dentist to freely move, without obstructions and where the legs will not be “hindered and restrained” under the back of the chair. 55 Symmetric (stable and balanced): The working field must be positioned in front of and centralized in relation to the chest of the dentist. Every time that the working field is not centralized in relation to the chest of the dentist, an asymmetric work posture will occur. It requires more muscular effort to maintain the balance and it will generate more fatigue and tiredness. The inclination and effort will lead to scoliosis. Other important disadvantage will be the difference in distance among the objects focused by the left and right ocular globe [62]. This difference in distance leads to more effort on the ocular muscles to correct the distortion of the image that will be generated, which will predispose prematurely the dentist to a presbyopia condition [24]. A symmetrical position is reached when there is a parallel relation to the imaginary lines that go through the pupils, shoulders, hips, knees, and feet completely laying on the ground. This also requires that the foot control of the chair is closely positioned to the foot of the dentist, so it is not necessary to stretch the leg to reach it.

55 Erectus: It is reached when we intentionally position the forward and upward, with the vertebral column in a neutral position, and the closest as possible to the shape that it has when it is in the orthostatic position (standing). This avoids overload of the intervertebral discs, herniated disc, hyperlordosis, hyperkyphosis, and scoliosis of the vertebral column. This way, when passively seated, the correct support on the upper and lateral parts of the pelvis, which must be proportioned by the support of the dental stool, is fundamental to increase stability and reduce the muscular overload. >> The healthy posture for the dental job is sitting, but this working position has also to be erectus, active, and symmetric.

The ISO 11226:2000/Cor 1:2006: standard “Ergonomics  – Evaluating the posture of static work” establishes the healthy limits for a job performed sitting and static and determines the ideal position considering the head, the torso, the arms, and the legs angles [31]. To reach an ideal posture, according to this standard, the column must be erect, the legs must remain perpendicular to the ground, and the tights must be parallel to the ground or slightly leaned, forming a 90° to a 125° angle on the knees and hip angle (. Fig. 2.2a). The head can lean up to 20° forward in relation to the column, while the torso can lean up to 10° forward (. Fig. 2.2a). The upper arms must present a maximum angulation of 20° on the forward inclination (. Fig. 2.2a).  

 

 

Tip

The dentist must pay attention to his body. The head should not lean more than up to 20° forward in relation to the column, while the torso can lean up to 10° forward. The upper arms must present a maximum angulation of 20° on the forward inclination.

The patient must be positioned in a way that the forearms of the operator are leaned, at least, 10° and the most to 15° upward, when the hands are in a position of operating (. Fig.  2.2a). This inclination of the forearms avoids the excessive frontal inclination of the torso, so it is possible to have a good vision of the operating field [26]. The elbows must be close to the body with a maximum lateral distance of 20° (. Fig. 2.2b) [26, 28]. It is very common to observe that the dentist and the dental students usually work with an excessive distance between the elbows, and always that the patient’s mouth is positioned above the recommended distance from the ground, which is 5–10  cm below the elbows when the dentist is well positioned in the stool. This patient’s position can avoid that the dentist leans the torso beyond the 10° forward, in the anteroposterior direction. To lean the body forward produces a reduction of body’s agility and increase the static load. The back and neck of the dentist should not lean or rotate laterally, and the top of the  

 

47 Ergonomics Principles Applied to the Dental Clinic

a

b

..      Fig. 2.2  Healthy work posture for the dentist according to the ISO 11226:2000 standard. a Side view; b back view

shoulders should stay parallel to the ground, which characterizes a symmetric and equilibrated posture, without muscular overload (. Fig. 2.2b) [26, 28]. On the other hand, the effective application of the rules to the postural needs of the dentist demonstrates a great challenge, because the working field (surface, tooth, quadrant, or region) cannot always be directed perpendicularly to the visual axis. In many cases, the use of the clinical mirror is essential because it facilitates the visualization without the need to lean laterally or forward, especially in procedures performed on the upper jaw, and even that, it is not always enough [28]. One difficulty is related to the angles formed by the thigh and the leg. When a 90° knee angle is adopted (. Fig. 2.3a), the space under the back of the chair is limited, especially when the patient is sitting down, forcing the dentist to back up from the patient and to lean forward to approach the working field, causing a compression on the abdominal region that will lead to a diminishing of the venous circulation [26]. This space becomes greater when we increase the angle to 110°, and it can go up to 125° (. Fig.  2.3b, c). Another additional benefit is that this increase, to at least 110°, propitiates less compression on the abdominal region, facilitating the blood circulation on this region. It also permits that the work posture of the dentist become more dynamic, prone to the movement, permitting the alternation of the position on a simple way, naturally and without obstacles, which is an essential condition, for example, when a procedure is performed on the first quadrant, comprehending the buccal, lingual, mesial, and distal surfaces. This  

 

 

mobility and freedom of movements are necessary when we do a cavity preparation that comprehends two or more surfaces, or even the preparation for a full crown that comprehends all surfaces of the tooth. On those cases, only asking for the patient to move the head left or right, backward or forward, may not be enough and requires that the dentist move himself more to the right or behind the patient. Consequently, there is a need for a work posture that is at the same time symmetrical, erect, balanced, and stable, but prone to the movement [26, 28]. Other benefit in using an angle greater or equal to 110° between the thigh and lower part of the leg is that this leads to a neutral positioning of the pelvis, slightly leaning forward and downward. When this angle is lower, close to 90°, there is an upper and backward leaning of the pelvis. Therefore, when the pelvis is raised and forced back, there is more tension on the lumbar region of the vertebral column, reducing its normal curvature and causing a compression on the intervertebral discs [31]. Kinematic chain balance and neutral working posture is most easily achieved by working in a higher sitting posture, with a 125° knee/hip angle, because it allows the patient’s chair to be raised, creating the necessary space for proper movement of the legs of the dentist under the back of the chair. However, currently, most of the dental stools offered on the global market have a flat seat; hence working in a higher sitting posture leads to a greater compression on the returning venous circulation, and, consequentially, there are more chances to have varicose veins because there is a greater support on the legs and less support on the coccygeal

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a

b

c

2

..      Fig. 2.3  Angle between the leg and the thigh. a 90° angle. Distance between 5 and 10 cm between the height of the elbows and the mouth of the patient; b 110° angle. The inadequate stool leads to a compression of the thigh (arrow). c Use of the saddle shaped stool (Salli System)

a

c

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d

..      Fig. 2.4  Dental stool with design of two-inclination seat, which allows the dentist to adopt a healthy work posture. a, c Stools with straight seats; b, d stool with double inclination. (Courtesy from Professor Paul A. Engels)

region (. Fig. 2.3b – arrow) [2]. So that does not happen, it is necessary that the dentist’s stool comprises a seat pan, consisting of a horizontal rear part for the pelvis, and an inclinable sloping down front part for the upper legs, with a vertically and horizontally adjustable back rest [13, 28]. . Figure 2.4 shows the Ghopec dental stool with an appropriate design, that allows the dentist to assume a passive as well as a dynamic posture [28]. Other option would be to use stools shaped like a horse’s saddle (Salli System), as it can be shown in . Fig. 2.5. On this type of seat, the support happened at the ischium bones in a  

 

 

simulation as if the individual was standing up, and because of that, there is no back in the stool. The angle on the knee region is found to be more adequate, which lowers the pressure on the knees, improves the joint metabolism (knee and hips), and lowers the risks of future problems, also contributing to improve the circulation on the legs. Because it is composed of two separate pars, it ventilates the genital region of the woman, which reduces the occurrence of infections and reduces the pressure on the masculine genital organ. This system also reduces pressure on the chest, on the ribs, and on the upper part of the column, increasing the inhaled oxygen

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49 Ergonomics Principles Applied to the Dental Clinic

Vianna and Arita [63] described a working position that is based on the logic performance concept, which is a scientific model of improved performance by means of emphasis on a more natural position, to do a finite task on a balanced posture. Studying the space relation between the operator and his work plane, it can be concluded that the dental work is much better performed on the midsagittal plane, with the hands, on the chest or heart level, in myocentric harmony (. Fig. 2.2). The dentist must sit with his feet completely supported on the ground, providing a position of equilibrium and a positive physiologic condition.  The greater the area in which a force acts on, the smaller the pressure and better distribution, so more favorable to the health of the feet. The feet must be parallel to the ground, in a way where the right foot is slightly ahead of the left foot, and this position can be alternated. The right foot must be free on a plane area to reach the command of the dental chair, without diverting the attention from the operating field. Furthermore, the shoes must be comfortable and loose [19]. The dentist should not sit on his legs and should always sit on the gluteus region, with the support on the ischium bones, which is part of the hip bones [2]. The whole seat surface must be used to support the operator’s weight. The compression of the tissues varies with the type of seat, been greater on the stools with a flat surface and lower on a saddle-shaped stool, as it can be seen on the . Fig. 2.6a, b. In relation to the angle formed by the gap between the legs, it can be between 25° and 45° (. Fig. 2.14).  

 

 

>> The dentist must sit with his feet completely supported on the ground, providing a position of equilibrium.

..      Fig. 2.5  Saddle-shaped stool (Salli System)

quantity. Furthermore, lowers the pressure on internal organs, especially on intestine and stomach (. Fig.  2.3c). Limitations are attributed to saddle stool which are related to increased angle in the lumbar spine when sitting with a 135° hip angle and muscle fatigue in the same region by the absence of the backrest [13]. A recent systematic review [50] has revealed that there is a limited number of studies and insufficient scientific evidence that using saddle stool leads to improved dentist’s sitting posture, and there are no studies on its effect to reduce neck pain and musculoskeletal pain. Therefore, prospective longitudinal studies that are necessary to strengthen the scientific evidence about its contribution and effect. However, the recommendation to use an angle >90° continues to be a problem for most of the dentist around the world, who may not have a stool with a proper design available on the market. In the case the stool does not have one of the mentioned designs and an angle >90° is used, the resulting forces on the tripod legs stool can push the stool backward and also result in the compression and venous obstruction on the thigh region. Therefore, in the abscence of an adequate stool, a 90° angle should be used. The incorrect drawing of the stool can seriously affect the health of the clinician, leading to an irreversible deformation of the vertebral column [2].  

In relation to the leaning of the body on the anteroposterior position, the ideal is to maintain the sitting positioning on a medium posture (. Fig.  2.7a). On this position, it is recomended a support on the upper pelvic region or lumbar [28], which alleviates the abdominal cavity, an important region for blood flow and digestion [2]. A slight leaning forward > During the procedure, the operator must be capable to keep hands and eyes on the working field without being worried about from where the next instrument will come.

The  concept that the less movement done, the less use of energy and the greater the productivity should be adopted [2]. The working surfaces to place the instruments must be in front of the patient, more or less 20 cm from his chin, on the frontal transference zone, next to the working area. The oral cavity of the patient, the dentist’s delivery unit, the assistant’s delivery unit, the top of the furniture with the equipment, and the trays with the instruments, must be placed on a hypothetical horizontal plane, from 5 to 10  cm above the elbow of the dentist (. Fig. 2.3a).  

2.2.3

Positioning of the Patients on the Chair

The patient must be, always as possible, positioned in a supine position (lying on his back), so that the dentist and the assistant can have a direct vision on the operating fields. One of the advantages of the supine position is that the patient’s tongue falls behind, blocking the pharynx, this way, even when the patient’s mouth is full of water he does not have the need to swallow. In addition, if any material or tool escapes the hands of the dentist, the chances of being swallowed are minimum, since the deglutition is harder on this position (. Fig.  2.11a, b) [2]. The working field on the mouth of the patient can be turned to the visual axis of the dentist in an easier way if the patient is in a supine position. On the supine position, the knees and the legs of the patients must be at the same level as the head (. Fig. 2.12). This replicates the position that most people adopt when they are sleeping for many hours without blocking the blood flow. The position of the patient when the legs are higher than the head for a prolonged time is not recommended [7]. Once the patient is in a supine position, the operator can lower the chair up to the point where the patient’s head is at his lap, so he will not have to raise the forearm above 15° or lean himself more than 10° to work at the patient’s mouth [7]. The dentist will have to lean excessively forward when the patient is at the same height or lower than his elbows. On the other side, when the mouth is positioned much higher than the level of the dentist’s elbow, the dentist will have to raise the shoulders, arching them and moving the elbows far away. As it has already been mentioned, the mouth of the patient must be 5–10 cm above the elbows of the dentist.  

 

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a

b

2

..      Fig. 2.11  Relation between the leaning of the head and the opening of the digestive and respiratory way. a Patient sitting with the oropharynx opened; b patient laying down with the oropharynx closed by the backing up of the tongue

tributing to the infection control. The operator will also not invade the breathing space of the patient, and this way will show consideration about his comfort throughout the treatment. For the working position currently recommended, the leaning of the chair’s back depends on where the dentist will be working in the oral cavity of the patient. The leaning of the articulated headrest of the chair must change according to the arch that is being treated. On the upper jaw, the patient must be on the supine position, and the headrest must be leaning backward. For procedures on the lower jaw, the headrest must be leaning forward (. Fig. 2.13a, b).  

..      Fig. 2.12  Adequate positioning of the patient on the supine position

It is important that both legs are positioned under the back of the chair, without being “restrained” or “blocked,” with the head of the patient, who is on the supine position, being able to alternate the position from 9 to 12 o’clock and keeping his posture. As it has already been mentioned, this is attained by adjusting the angle between the leg and the thigh above 90° using an appropriated stool. Therefore, the correct working height depends on the dentist’s height and when he is positioned correctly on the stool. This way, the dentist and the assistant must be at compatible heights, so that the adjustment of the chair for the dentist is not uncomfortable for the assistant. The final visual adjustments and the access to all quarters of the mouth can be reached by rotating the head of the patient. The torso of the dentist must be the closest as possible to the back of the chair; this way, the head of the patient will be leaning on his lap at a distance of 30–40 cm below the eyes/safety glasses, providing comfort for the vision and con-

>> One of the advantages of the supine position is that the patient’s tongue falls behind, blocking the pharynx.

2.2.4

Positioning of the Patient’s Head

The patient’s head must be placed in a way that the working field is facing the dentist’s visual axis, considering that he is correctly positioned on the stool. To reach this position, the patient’s head can be moved in three axis and three directions (. Fig. 2.13a–f): 55 Forward, by flexion, for a horizontal position of the lower jaw. Backward, by extension, so that the occlusal plane of the upper jaw can be switched in some cases on a 20–25° angle in relation to the vertical plane. The further the head is positioned backward, the more favorable is to work with a direct vision in a correct posture on the upper jaw (. Fig. 2.13a, b). 55 To the left or right by the side flexion, positioning the head of the patient on a 30–40° angle sideways in relation to the body’s long axis. This movement is  

 

55 Ergonomics Principles Applied to the Dental Clinic

a

b

c

d

e

f

..      Fig. 2.13  Movement of the patient’s head in three ways to place the working field perpendicularly to the visual axis of the dentist. a Forward; b backward; c leaning to the left; d leaning to the right; e right rotation; f left rotation

necessary to put the operating field on the patient’s mouth on a symmetrical plane of the dentist (. Fig. 2.13c, d). 55 To the left or right, rotating along the longitudinal axis of the head (. Fig. 2.13e, f).

2.2.5

 ositioning the Operating Field P in Relation to the Dentist

 

 

Tip

It is easier to move the patient’s head than try only to adjust the dentist’s position to see the operating field.

It is frequent for us to see that the operating field on a patient’s mouth is not directed toward the dentist, and it is placed asymmetrically in front of him, resulting in an asymmetric and stressful operating posture. This must be avoided in a way that the symmetrical posture can be kept. The principles for the correct positioning of the operating field are described next: 55 The operating field must be placed symmetrically, straight in front of the chest of the dentist, at a distance

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of 20–25 cm from the sternum bone. In addition, it must be placed in a height that allows a correct working posture. 55 The clinician must look perpendicularly to the operating field or to the mirror. If this is not possible, as it happens on the posterior region of the mouth or when using a handpiece, the field or the mirror must be as perpendicular as possible. The rotation of the patient’s head allows the good positioning on the visual field. It can be turned in three directions, according to the previous description, to promote this vision. If the head of a bur or instrument is positioned on the sightline, interfering with the good visualization, the patient’s head is rotated and the dentist position is adjusted instead of the dentist moving his torso and head laterally to reach more visibility. After defining those general rules, taking in consideration the position of the operating field in the patient’s mouth, the question is how it can be reached and how the arches of the patient must be placed. This position depends completely on the procedure to be performed: 55 When a procedure is done on the mandibular occlusal plane, the dentist must sit on the side of the patient on a position between 9 and 10 o’clock, for the right-handed people, and the occlusal plane will be placed more or less horizontally. The patient’s head will be turned to the dentist in a way that he looks perpendicularly to the occlusal plane. If the lower jaw is not placed like that, but in an oblique way, the dentist will have to raise the right arm to reach the operating field. 55 When a procedure is done on the mandibular occlusal plane, from behind the patient (on the position from 10:30 to 12 o’clock for the right-handed people), the occlusal plane on the lower jaw is placed approximately 40° in relation to the horizontal plane, in a way that the operating field is viewed perpendicularly, with the help to the head’s rotation. 55 When treating the maxillary occlusal plane, with an indirect vision from behind the patient, the occlusal plane of the upper jaw is turned around 25° backward in relation to the vertical plane. Followed by a rotation of the head, it is placed on the correct position in relation to the mirror. Those 25° of rotation promote a great adjustment for the necessary position of the mirror. The problem with most headrests is that it is impossible to position the upper jaw occlusal plane at 25° backward. Hence, the dentist is forced to lean the torso forward to obtain a better visibility of the operating field. 55 When procedures are done on the buccal and lingual surfaces of the teeth, the dentist must place himself on the side of the patient, on a position between 9 and 11 o’clock, with a direct vision, except for the anterior teeth. 55 The more the dentist wants to work on the upper jaw with direct vision, the more the patient’s head needs to be turned backward. However, the possibility to do that must be evaluated.

Tip

The more the dentist wants to work on the upper jaw with direct vision, the more the patient’s head needs to be turned backward.

2.2.6

 ositioning of the Operating Field P in Relation to the Assistant

The assistant plays an important role on the productivity and on the improvement of the work quality inside a dental office. Therefore, the dentist divides with her some of his secondary attributions, such as some complementary tasks, saving the time of the clinician and leaving to him the work that only he can do [21]. As advantages of the assisted work, there is the reduction on the movement quantity, that the dentist would have to perform if he was working alone, reducing the physical and mental fatigue. In addition, the work at four hands allows a higher performance, reducing the duration of the treatment [21]. It will be the assistant’s duty to accommodate the patient’s head and to open his mouth, putting away his tongue and cheeks, suctioning the blood and saliva, always placing the operating field to the direct vision field of the dentist [2]. >> The assistant plays an important role on the productivity and on the improvement of the work quality inside a dental office. Therefore, the dentist divides with her some of his secondary attributions, saving the time and leaving to him the work that only he can do.

The dentist’s assistants must be capable to work sitting down at a healthy position, similar to the posture described for the dentist. However, she should occupy the position that goes from 2 to 4 o’clock [2]. When the dentist sits at the 12 o’clock position, this is almost impossible. The assistant will have to sit with the legs slightly separated, and so it does not interfere with the movement. The assistant’s legs must be synchronized with the dentist’s legs (. Fig. 2.14) [2]. At this position, she will avoid the torsion of the column to the left and the raising of the arms during the operative procedures, being better located in relation to the delivery unit, to reach with the left hand her elements and to help the dentist. Her back should rest on the back of the stool and slightly leaning forward. Her head must be leaned downward, visualizing the working field [2]. Both the dentist and the assistant must have all the material to the reach of their hands. The assistant should not move the whole arm, and for that, it is suggested that a third assistant to prepare and bring the materials that are more distant [2]. Another way to reach this goal is to do an effective previous planning of the tray, and placing it on the ideal distance, to reach all the material and instruments that will be necessary during treatment. The adjustments on the patient’s  position must be performed with the aid of the assistant, up to the point where  

57 Ergonomics Principles Applied to the Dental Clinic

..      Fig. 2.14  Synchronization of the dentist’s and assistant’s legs

those relations are established. When a deviation on the posture is noticed, she can communicate politely with the clinician asking: “Are you comfortable?” This is a sign that maybe a rearrangement on the position is needed. The assistant needs to be capable to see and have favorable access to the oral cavity, at least of the teeth or the area that is being treated. To increase visibility, the height of the assistant’s stool could be at least 10–15 cm above the dentist’s head (. Fig. 2.15). To make it possible, it is necessary that the assistant’s stool has footrest. However, when this special stool is not available, it must be adjusted so that the head of the assistant is at the same height of the dentist’s head.  

2.2.7

The Use of Overhead Chair Light

The visual performance influences directly the efficiency of the dentist’s work. The better the clinician can see, the faster and more reliable the work will be. The main components of the visual performance are the ability to see small details (visual sharpness) and the ability to see small contrast (contrast sensitivity). The light at the work environment must be well planned to allow a good dentistry to be performed, a professional activity that requires accuracy and details. The perfect light at the dental office will reduce the fatigue and the incidence of visual fatigue. The environment next to the mouth of the patient must be lighted with at least 1/10 of the light over the mouth. For example, if the light over the mouth has a illuminance of 20,000 LUX (lx), then the surroundings must be lighted with at least 2000 lx and the room with 1000 lx. >> The better the clinician can see, the faster and more reliable the work will be.

One of the most frequent mistakes done by the dentists is in relation to the incorrect positioning of the dental overhead light, putting it in front of the patient and perpendicularly to the visual axis. This causes the formation of shadows by the interposition of the hands and instruments between the light and the object to be seen [62]. The light beam must be

..      Fig. 2.15  Adequate vertical relation between the assistant and the dentist for better visualization

directed nearly parallel to the dentist’s line of sight, without shadows, with a maximum deviation of 15°. Proper positioning of the dental operating light will avoid shadows behind the lips, teeth, and face, under the hand and on the operating field or around it (. Fig. 2.16a, b). Visual sharpness does not indefinitely get better with crescent light levels; there is a peak when the luminance is around 1000 cd/m2 (candela per square meter). Therefore, the illumination above this value does not bring any benefit in terms of vision sharpness. A best level of illumination also does not exist, because it depends from each observer and on the reflexivity of the working area. The illumination from the dental light must go from 8000 to 24,000 lx, which corresponds to 200 to 2000 cd/m2 of the light inside the mouth. The illuminance of 8000 lx is enough to visually discriminate a white tooth, and 24,000 lx is more appropriate for the visualization during procedures done in darker areas inside the patient’s mouth, for example, during the procedures on the molars. The light level from the dental chair light must be easy to adjust. In combination with other sources, the illuminance of the mouth must not exceed 30,000 lx. Greater light levels cause visual discomfort and reduction of visual sharpness. The correct distance of the overhead light to the operating field (patient’s mouth) must be around 70–80 cm, and the environment’s light must be compatible with the illumination inside the oral cavity, allowing the gradual accommodation of the eyes [17]. When the dental light is positioned at 70 cm apart from the patient’s mouth, it must form a rectangle of light with the concentrated area and limited by 10 cm height and 20 cm width, in a way that there is no direct light beam to the patient’s eyes, which causes dazzle and discomfort. Therefore, when the patient leans laterally together with the rotation of the head, it is important that the light beam may follow this position of the mouth without causing discomfort for the patient. Near the mouth, instrument that have a reflectivity similar to mouth should be choosen. Instruments with dull surfaces are preferable to avoid strong reflection, that will cause  

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b

a

2

..      Fig. 2.16  Correct positioning of the dental light to avoid the appearance of shadows and to improve the illumination

tension on the eyes and reduction of the eye sharpness. In addition, white and black objects should also be avoided. Other important factor for the correct positioning of the light beam of the dental chair light is the need to have three rotating axis. This is important so the beam of light can follow the movement of the patient’s head and, consequentially, his mouth. It is common that the mouth is placed on an oblique manner in relation to the headrest, on the vertical, horizontal, and depth ways. The length of the chair light’s arm must be enough to place the light on the side and above the head of the dentist, even if he is in any position between 9 and 12 o’clock. Especially, when he places himself at 12 o’clock, the light must be placed according to the clinician’s visual axis, being at most 15° laterally or above the dentist’s head, being this information little known and applied by most clinicians. 2.2.8

Vision of the Teeth to Be Treated

The operator can use two forms to see the operating field in the oral cavity, the direct and indirect vision. The direct vision occurs when the operator looks directly to the cavity preparation or the place to be treated; the indirect vision requires the operator to look through a mirror to see the area to be treated. The indirect vision eliminates the need for the operator to lean to see the operating field. To treat the occlusal surface of the second upper molar on the right side, even with the patient on the supine position, maybe the clinician will need to lean a little to have a direct vision. The use of a mirror will allow the operator to be seated in a healthy posture and observe the operating field satisfactorily using an indirect vision. >> The direct vision occurs when the operator looks directly to the cavity preparation or the place to be treated; the indirect vision requires the operator to look through a mirror to see the area to be treated. The indirect vision eliminates the need for the operator to lean to see the operating field.

Even if the dentist is in an adequate posture, the patient and operating field are on a correct position, and it is hard not to lean the head more than 20° as recomended. Due to that, special glasses were developed for the dentist, so it can allow an adequate position of the head and neck (. Fig.  2.17a–f). Those glasses have a piece of a prism on the lower part of the lens, and they are tilted. This way, when the dentist directs his vision to this area of the glasses, there is no need to lean the head and the neck. Others also present magnifying lens to enlarge the image.  

 ypes of Movements During T the Dental Treatment

2.2.9

The movements executed by the dentist and the assistant can be divided into five classes, with increasing complexity order [6]: 55 Class 1 – Finger movement. For example, the root canal preparation 55 Class 2 – Finger and wrist movement. For example, cavity preparation 55 Class 3 – Finger, wrist, and elbows (forearm). It is important that this occurs inside the ideal space in the transference zone. For example, to reach the high-speed handpiece at the delivery unit 55 Class 4 – Movement of the whole arm. It is the maximum reaching area. For example, open an auxiliary drawer when it is slightly farther than the transference zone and inside the functional working circle (. Fig. 2.18) 55 Class 5 – Torsions of the body and displacement. For example, to reach the suction across the patient, at the assistant’s side  

From all those movements, the ones in Classes 4 and 5 are the ones more difficult and time-consuming, because they need more muscle activity, new visual accommodation, and new focus on the operating field. Movement 5 is eliminated by the

59 Ergonomics Principles Applied to the Dental Clinic

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b

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..      Fig. 2.17  a Special glasses with a prism segment to correct the leaning of the head; b glasses with image magnification and correction the head position; c posture without the glasses; d posture with the prismatic glasses; e–f posture with the image magnification glasses

work with an assistant, and in case she is efficient, it can even eliminate the movements Class 4, leaving for the dentist only movements Class 1, 2 and 3. Therefore, movements 4 and 5 must be always avoided, and this rule is applied to the dentist and the assistant [2]. The correct posture can be easily maintained if the operator remembers that the operating field must be positioned in his direction. >> The movements of the whole arm, torsions of the body, and displacements produce more tiredness and are most time-consuming, because they need more muscle activity, new visual accommodation, and new

focus on the operating field. Therefore, they should always be avoided, and this rule is applied to the dentist and the assistant.

2.2.10 

Ways to Grasp the Hand Instruments

During the dental procedure, the hand instruments can be grasped by the hands in different ways, depending on the dental arch to be treated and the work to be performed. To guarantee the correct positioning and the precision of the job, the hands must be rested, which also avoids accidents.

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Class 4 movement. (Scheme kindly supplied by the Dabi-Atlante company)

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On the lower teeth, a modified pen grasp is used (. Fig.  2.19a). It is a grasp that allows more gentle movements. The name means that it is similar to the one when we hold a pen, but not identical. The pads of thumb, index, and middle fingers contact the instrument, while the tip of the ring and little finger is slightly placed on a dental surface nearby, at the same arch, as a rest point. The palm of the hand is not facing the operator. The pad of the middle finger is placed on the topside of the instrument, and its work, together with the wrist and the arm, produces the pressure on the blade of the instrument. The instrument must not rest on the first articulation of the middle finger, as a conventional pen, which restrings the pressure applied [56]. On the upper teeth, a modified and inverted pen grasp must be applied (. Fig. 2.19b). The position of the fingers is the same position of the modified pen grasp. However, the hand is turned, and the palm of the hand faces the operator [56]. For the upper teeth, when more force is needed, a palm-andthumb grasp can be adopted (. Fig. 2.19c). It is similar to the position used to hold a knife when peeling an orange. The  

 

 

a

handles are placed on the palm of the hand and held tightly by all fingers except the thumb, which will rest on a tooth right next to it, on the same arch, for firmness. For an adequate control, this grasp form requires careful use [56]. >> During the dental procedure, the hand instruments can be grasped by the hands in different ways, depending on the dental arch to be treated and the work to be performed.

2.2.11 

Rest Places

To obtain a correct rest place for the instrument is fundamental for a precision dental procedure. Extra oral rest and the rest at the opposing arch should be avoided due to the possibility of the patient to move. Whenever possible, the dentist should opt for a rest point on the teeth nearby the place where the treatment is being performed. The closest the rest to the area of working, the more thrust worthy it is.

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..      Fig. 2.19  Ways to grasp the hand instruments. a Modified pen grasp; b inverted and modified pen grasp; c palm-and-thumb grasp

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However, in some situations, it is not possible to establish a rest place on a tooth structure and the soft tissues must be used. Neither the soft tissue nor the hard tissues farther from the operating area allow a reliable control. Occasionally, it is also not possible to establish a regular rest using the fingers of the same hand that is grasping  the instruments. On those cases, the control can be reached using an index finger  of the other hand, touching the instrument on the handle, or using an indirect rest. That means that the operating hand will rest on the other hand, which will rest on a stable oral structure [56]. On the anterior teeth, there is the possibility to directly visualize the surfaces to be treated. However, in some regions of the mouth, this can become very difficult, if not impossible, that is the reason we opt for an indirect vision, through the reflected image on an oral mirror.

2.2.11.1  Lower Arch

At this arch, the modified pen grasp  is recommended, with rest place on the teeth of the same arch, next to the cavity preparation, using the ring and little finger (. Fig.  2.20a). When working on the buccal surface, the mirror is used  to displace  the check musculature to improve the visualization  (. Fig.  2.20b). When working on the lingual surface, the mirror  is used to displace the tongue (. Fig. 2.20c).  

 

 

2.2.11.2  Upper Arch

On this arch, the modified and inverted pen grasp is recommended. On the right side of the patient, the use of the clinical mirror improves the illumination of the operating field when using the direct vision or allows the indirect vision. The rest place is on the neighboring teeth on the same arch (. Fig. 2.21a). On the left side, the use of the clinical mirror improves the illumination at the operating field and allows the indirect vision, besides helping to displace  the check musculature. The rest place is at the same arch, on the opposing side (. Fig. 2.21b). When the palm-and-thumb grasp is used, the tip of the thumb is placed on the tooth that is being treated in a neighboring tooth or on a convenient area at the same arch.  

Tip

To properly grasp the instrument and rest the hand is essential for stability and precision while working. Rest your finger on teeth nearby the place where you are doing out intervention.

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..      Fig. 2.20  Rest areas using modified pen grasp of dental instruments at the lower arch. a Rest on the teeth from the same arch; b check musculature displacement; c tongue displacement

63 Ergonomics Principles Applied to the Dental Clinic

a

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..      Fig. 2.21  Rest areas for the use of instruments on the upper dental arch. a Rest on the neighboring teeth on the same arch at the right side; b work on the left side of the patient and rest on the right side

2.2.12 

Work Environmental Conditions

High stress sources at work are the unfavorable environmental conditions, such as the excessive heat, noise, and vibrations. Those factors raise the risk of accidents and produce discomfort and damage to the health [30]. The environmental comfort is an extremely important point for the dentist, who spends his whole day inside a closed room and concentrated on the treatment of his patients. Studies developed by Heimstra and McFarling [23] have already mentioned the complexity involved on the creation of a satisfactory environmental condition, for a group of people who work at the same place, because each worker presents a different level of physical and psychological sensitivity. The authors report that the noise, temperature, humidity, and illumination can produce comfort or annoyance, affecting the performance of the individual. 2.2.12.1  Noise

When looking for noise definition, the literature is ambiguous, but in a general way, the noise can be defined as an undesirable sound. There is a subjective and a physic definition for noise, described as followed: 55 Subjective definition: Noise is all the annoying or unhealthy audible sensation. 55 Physic definition: Noise is all not periodical acoustic phenomenon without harmonic components defined. On the last decades, more people have been affected by the noise, but since 1989, the World Health Organization started to treat noise as a public health problem. The human ear can notice a great range of sound frequencies from 20 to 20,000 Hz, and the intensity (volume) of the sound is defined by the level of sound pressure, varying approximately from 0 to 130 decibels. The noise can cause damage on the hearing organ, as deafness, that is characterized by a deficit in the range of 3000–6000 Hz, or fatigue, which manifests by a temporary increase of

the hearing threshold. For prevention, there are protective hearing devices, such as earplugs and earmuffs, but on the  other hand, they can cause deficiency on the ­communication. When the noise happens on a nonconstant way or even in an unexpected way, it can interfere with the concentration, reducing the intellectual performance and making it harder to do more complex tasks. The noises that are not so loud can only cause a slight bothering, but the greater the intensity, frequency/duration and the age of the individual, the more damage the noise will cause [36]. According to Fernandes et al. [16], the dentist is subjected to two types of noises: 55 Outside the working environment: Traffic, voices, compressor (when outside the work environment), telephone, bell, and sounds coming from the waiting room 55 Inside the working environment: Dental handpieces, air compressor (when inside the work environment), suction, amalgamator, air conditioner, among others According to the standards from the Occupational Safety and Health Act (OSHA), 80 decibels (dBA) is at the maximum tolerable limits of sound for the dentist [9]. The manufacturers in general claim that the noise level of their dental treatment unit (especially of the handpieces) is below 80 dBA. The longer the dentist is exposed to the noise during his professional life, the greater will be the chances of a reduction of the hearing capacity [49]. The noise-damaging effects can also produce many physical, mental, and social problems on the dentist. Tip

The use of handpieces with low noise emission is a very important point when deciding the purchasing of a new one.

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2.2.12.2  Temperature

2.2.12.4  Illumination

The stress caused by the heat or cold at work environment is motive of concern because it affects, besides productivity, the physical and mental health of the worker. The literature the ideal temperature to work is between 16 and 22 °C, but in countries with a hot weather, it can be accepted up to 5 °C more. Other standards state a temperature between 20° and 23°, emphasizing that the difference in temperature in the same environment cannot be >4 °C. According to Bauman [3], technically comfortable environments favor the achievement of high quality services; the worker feels more attracted by the working post, by his activity and by the positive results of his tasks. It  is noticed less complaints in relation to the individual necessities and in relation to the diseases acquired on those environments, which result in a drop on the operational costs. According to Grandjean [20], “the excessive heat at working places leads to tiredness and drowsiness, which reduces prompt responses and increase the chances of  mistakes  to happen.” Therefore, the thermal factor produces a great influence in the comfort during the work. The temperature, air speed, solar radiation, and relative humidity are fundamental for a comfortable thermal sensation, which also depends on the type of work being performed and the kind of  clothes worn. The speed of air displacement should not be superior to 0.2 m/s. Guiton [22] states in his studies that the human body presents its own mechanism to produce heat. The heat generated by the metabolic activity exceeds the need to maintain the body temperature in its normal level, of approximately 37 °C. That means that we should not need any other external heating source and that the most important thing would be to eliminate this excess of heat, without affecting the functioning of the organism.  Our working environment should allow the control of the temperature, avoiding an extremely hot or cold sensation.

In all working places, there must be adequate illumination, natural or artificial, but always accordingly to the nature of the activity. It should be uniformly distributed and diffuse, avoiding obfuscation, reflection, shadows, and excessive contrasts. A well-illuminated environment with light colors on the background, brings to  the environment visual comfort and rest, improving the quality of life and at work. The light level is measured in lux. A well-illuminated environment is important to have visual comfort, avoiding, this way, the loss of sight sharpness, fatigue, misreading, and work accidents. Some studies has  shown that bad light conditions can cause psychosomatics problems, as stress, and greater sensibility to the microbial attack. The effects of the very luminous environments over the vision are significant in a long-­term. In cases of obfuscation there is always the risk of accidents. The lack of adequate illumination can cause visual fatigue, characterized by the irritation and pain on the eyes, redness on the conjunctiva, modification on the blinking pattern, tearing, photophobia (light intolerance), diplopy (double vision), feeling of blurred vision, perception of colored aura around objects, abnormal persistence of after-images, and instability of the image on its optical definition and in space. It usually comes with other symptoms as headaches. The following are some very important points in relation to the illumination: 55 Type of light bulb and luminaire: Depends especially on the environment’s characteristics and on the activities to be developed. 55 Quantity of light bulbs/luminaire: An adequate number should be installed with the goal to reach the needed illumination, with base on a technical project, which will consider the variables from the environment. 55 Distribution and placement of the luminaires: The luminaires must be placed on the environment in a way to give a homogeneous and uniform illumination, considering the physical arrangement of the place, avoiding contrasts and shadows at the working areas. 55 Maintenance: The burnt out light bulbs or with inadequate illumination must be changed, and the good ones frequently cleaned. 55 Colors: The colors of the walls, dental treatment unit, and furniture must be chosen in a way that they have a good light reflection in the room. The working table and the delivery unit, for example, cannot have a very reflexive surface because the incidence of light could obfuscate the eyes. 55 Variation of light: The accentuated difference between the levels of illumination between one environment and another can damage the eyes, bringing fatigue and loss of sharpness; this occurs due to a sudden dilatation/ contraction of the vision muscles, even in a small-time interval. When repeated many times during the years, it could cause an injury.

>> The thermal factor produces a great influence in the comfort during the work. The temperature and air speed, solar radiation, and relative humidity are fundamental for a comfortable thermal sensation, and it also depends on the type of work being performed and the clothes worn.

2.2.12.3  Relative Humidity of the air

The relative humidity must not  be below 40 or higher than 60% in the work environment. The exposition to environments with levels of humidity far from the ideal may cause diseases, but can aggravate some preexisting ones,  such as osteomuscular diseases (generally called rheumatism), the lung, and skin diseases. >> The exposition to environments with different relative humidity can aggravate some preexisting osteomuscular, lung, and skin diseases.

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55 Age: The greater the age of the people at the working place, the greater should be the light intensity. 55 Direct incidence: Windows should be positioned so that there is no excess of natural light within the work environment. In dental offices located in the southern hemisphere, it is recommended that the window be directed in a north-northeast direction, and in cases where it faces south, it is recommended that there is a clear wall for natural light to be reflected into the interior of the environment. In dental offices located in the northern hemisphere, it is recommended that they should be facing south or north, and that the design of the roof and windows be planned according to the path of the sun to prevent the direct incidence of solar rays during the summer, and allow their entry during the winter. Regardless of which hemisphere the dental office is located, when the window is directed to the east, there is an excess of illumination in the morning and a shortage in the afternoon, the opposite occurring when the window is facing west. In these cases, it is mandatory to use barriers (internal or external) to avoid excess light, forcing the use of artificial lighting. >> A well-illuminated environment, with light colors on the background, brings to the environment visual comfort and rest, improving the quality of life during the working hours.

2.3

Work-Related Musculoskeletal Disorders

The multitissue lesions of the upper limbs of the motor system, attributed to be caused by repetitive strains at work, previously known as repetitive strain injuries (RSI), were renamed to work-related musculoskeletal disorders (WMSD), because it is the most appropriate name. The WMSD, according to Lopes [38], is characterized by the affections of the motor system, upper limbs, shoulder and neck, that have direct relation with the requirements for the repetitive, fast and  continuous movements of the tasks executed. In addition, the stress generated during the dental practice is other factor that can contribute for the development of the WMSD [1]. The WMSD is defined as a phenomenon related to work, characterized by the incidence of different symptoms at the same time or not, with pain, paralysis, heavy feeling, and recurrent fatigue, generally on the upper limbs [45]. Those disturbances, related to the work, initially cause pain and can evolve to the incapacity to do some movements, temporarily or permanently. Therefore, the early detection of the lesions can be essential to avoid the worsening of the disease, long treatment, and medical conditions that would take the professional away from his practice [1].

When there is not a good relation among the different parts of the body, a bad posture can happen, inducing to an increase of aggression to the supporting structures, resulting in a less efficient balance of the body over the legs. During the dental work, many inadequate postures occur, which could lead to musculoskeletal overload over some body segments, which could cause lumbar inflammation, cervical pain, and aches [1]. According to Rio [54], the following inadequate posture could occur: 55 Flexion, extension, lateral leaning, and lateral rotation of the neck 55 Abducted arms 55 Elevated arms above the shoulder levels 55 Flexion of the forearms higher than 90° 55 Pronation and supination of the upper limbs 55 Ulnar and radial deviation from the body 55 Lateral leaning and torsion of the vertebral column The problems caused  by the incorrect work posture are a lumbar and back pain, and affect the feet and lower limbs. It is called lumbar pain all and any pain located on the lumbar column. Many are the causes for the lumbar pain, and the treatment can be conservative, which will include specific medication, physiotherapy, back braces, and medical orientation or surgical treatment, which involves different types of surgeries [1]. According to Knoplich [35], the work on a sitting position increases the intradiscal pressure, increasing the bad adjustment of the disc and column. In addition, the dentist executes movements of lateral leaning, flexions, and extensions, which lead to defects of postural origin, named scoliosis, kyphosis, and lordosis. The scoliosis is a lateral deviation, permanent to the vertebral column. When the inclination can be corrected voluntarily, it is a scoliotic attitude. Kyphosis is sagittal curves on the normal vertebral column on the anterior concavity, located on the dorsal and sacrum and coccyx segment, while lordosis is the posterior concavity, specifically in the cervical and lumbar region [19]. When a dissolution or destruction of vertebrae occurs, it is called spondylosis. >> Incorrect work posture causes lumbar and back pain and affects the feet and lower limbs.

The dentists can be affected by return venous circulation problems, as varicose veins and thickening of the nails, and also the formation of bunion, callus, and hallux valgus, which happens because of the use of badly dimensioned shoes that are made from inadequate fabrics or materials. It is essential that the dentist works with his feet completely rested on the ground, keeping, this way, a balanced position and a positive physiological factor on the physical condition, lowering the pressure on the feet [1]. If hand injuries happens to the dentist, this could force him to leave work for a short or long period  many times throughout his professional life. The improper use of dental instruments can promode hands injuries and are related to

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constant and repetitive force, with a pinching movement of the fingers and thumbs, combined with extreme hand movements. The carpal tunnel syndrome  has the highest prevalence among the dentists. The carpal tunnel is limited by the concave arches formed by the carpal bones of the hands and by the transverse carpal ligament, holding the carpal nerve, nine flexor tendons and blood vessels, as can be observed on . Fig. 2.22a–i.  

>> The improper use of the instruments can produce the carpal tunnel syndrome, resulting in motor and functional alterations, pain, swelling, and stiffness of the hand, requiring surgical treatment by surgery.

When the hand is flexed, it extends or deviates from the central position; the volume of the tunnel is reduced and the internal pressure increases (. Fig. 2.23a, b). According to Osamura et al. [48], the most characteristic tissue in the carpal tunnel is the subsynovial connective tissue and its small  permeability can explain the predisposition of the region to increase the pressure, causing this neuropathy.  

Oh et al. [47], verified that ultra-structural changes occur in the subsynovial connective tissue from patients with carpal tunnel syndrome, as deformed collagen fibers, that appear to be in a spiral form, and phagocytosis of the elastic fibers. The tendons, when compressed, press the nerve, which, with chronicle repetition of the movement, become inflamed and suffer damages. This causes sensitive, motor, and functional alterations, pain, swelling, and stiffness of the hand. If this situation continues for a period of, for example, 1 or 2 years, a paresthesia sensation on the wrist level, pain, and swelling of the fingers will occur. Later, if the situation persists, from 2 to 8 years, a reduction of the pinching force will appear and an atrophy of the hand’s muscles will  eventually result in incapacity to hold an instrument. Once the damage is installed, the treatment consists in immobilization of the hand, hydrocortisone injections  and finally surgical treatment, depending on the degree of the nerve’s alterations. The presence of the carpal tunnel syndrome can be confirmed by the positive result on

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..      Fig. 2.22  Hand’s sections in different levels. a Carpal bone; b thenar muscle; c transverse carpal ligament; d median nerve; e concave arch of the carpal bones; f flexor tendons; g cubital nerve; h–i flexor tendons

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..      Fig. 2.23  a Correct work positioning of the hand; b flexed hand, resulting in a diminishing of the carpal tunnel volume

67 Ergonomics Principles Applied to the Dental Clinic

the Phalen’s maneuver, which consists on the placement of the dorsum of the hands in contact to each other, with the individual with the shoulders and elbows in 90°. With this maneuver, the mediated nerve is pressed against the ventral retinaculum and reproduces the night symptoms, which is “tingling” (hypoesthesia) [11]. 2.3.1

Occupational Diseases Epidemiology

The application of the ergonomic principles in the dental office allows rationalizing the work, allowing the elimination of nonproductive maneuvers. This way the clinician produces more and faster, with less stress and more results, providing at the same time more comfort and safety to the patient [2]. Therefore, it is fundamental to avoid or to correct the wrong working habits, the ones that can bring serious damage to the clinician. Seventy-two percent of the dentists examined by Rundcrantz et al. [59] reported complained about some discomfort or pain on the head, neck, or shoulders. Similar results were reports by Kerosuo et al. [14], who observed that 70% of the general dental practitioners had musculoskeletal symptoms. They also observed that the symptoms were more frequent on women. Some specific body areas are associated with injuries related the dental practice as described as followed: 55 Carpal tunnel syndrome – Problem associated with the continuous flexion and extension of the wrist 55 Shoulder and neck ache – Tension or flexion of the shoulders for more than 1 h/day 55 Back and neck ache – Extension or elevation of the arms for a long period 55 Low back region ache – Torsion of the body for a long period According to Wagner [65], from all the occupational diseases affecting the dentists, the ones that are caused by the posture are those with the most neglected prevention, because they will only feel its effects with the passing of the years. It is very hard to convince the young dental students in the universities to take prophylactic measurements in relation to the damages to the column. Even with the ergonomic coming to help the profession, there are excessive working hours spent at the clinic. In addition, there are idiopathic predispositions from each one to specific types of skeletal degeneration, such as spondylosis and intervertebral disc flaccidity, that sooner or later compromise the column of some individuals, while others never come to manifest any symptom, at least, during the productive practice of his profession [18]. On the Netherlands, a study was done to evaluate the posture adopted by 1250 dentists throughout dental procedures, which was named the Sonde Project [27]. The authors concluded that high percentages of deviations in relation to the correct working posture are practiced by the clinicians, as they are shown here:

55 About 89% show forward flexion of the head, exceeding in 20°, which is considered the limit for a healthy position. 55 About 61% show rotation of the neck combined with strong flexion forward. 55 About 63% show flexion of the posterior part of the body exceeding in 20°. 55 About 36% work with the neck turned combined with the torsion of the back. 55 About 35% keep their forearms on an angle higher than 20°. 55 About 32% keep their forearms on an angle higher than 25°above the horizontal line. 55 About 25% rest their hands wrongly when working. 55 About 47% do not grasp correctly the instruments (on the modified pen position). 55 About 20% show strong flexion of the wrist. 55 About 65% work with a stool with a wrong back support. 55 About 75% of the dentists work without the head of the patient being symmetrically in front of them. 55 About 32% work with their feet and legs farther than the necessary from the dental chair. 55 About 55% work for more than 7 h sitting down every day. 55 About 75% work with inadequate light and differences in light distribution that are not according to the standards. Santos Filho and Barreto [61] performed a study evaluating the prevalence and sysmtoms of osteomuscular pain on 358 dentists, using a self-reporting questionnaire, and they observed the prevalence of pain on the upper segment was 58%, being 22% on the arms, 21% on the column, 20% on the neck, and 17% on the shoulder; 26% reported that the pain was daily and 40% was moderate/strong. According to Méndez and Gómez-Conesa [43], the information about the arrangement of the dental treatment unit and the adequate posture at work can reduce the musculoskeletal symptoms risk. According to Melis et al. [42], there is a critical need to insert the topics of ergonomics on the educational system to prevent the risks for the future clinicians. A study performed with students of a university demonstrated that more than 70% of them report pain already on the third year of school. It also demonstrated that this number increased gradually from the first to the last year of the course. The authors concluded that the teaching of ergonomics needs to be better elaborated and worked throughout undergraduate phase [55]. >> The application of the ergonomic principles on the dental office allows rationalizing the work, allowing the clinician the elimination of nonproductive maneuvers. This way the clinician produces more and faster, with less stress and more results, providing at the same time more comfort and safety to the patient.

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2.3.2

WMSD Prevention

It is important to adapt the work environment to the operator instead of the operator having to adapt to the environment [2]. This concept requires that the dentists take a favorable sited posture and then place the patient, assistant, and delivery unit in relation to his position. This working condition is called “balanced posture” [8]. It does not intend to have the operators sitting like a statue but to establish a series of rules that may help them  to obtain comfort while working. The specialists agree when they say that the frequent change in position, for those who work sitting down, is the key to prevent problems on the column [25, 26, 28]. >> It is important to adapt the work environment of the operator instead of the operator having to adapt to the environment.

The adoption of a healthy posture at work is fundamental on the prevention of WMSD.  Besides having dental treatment unit that permits to work correctly, it is important that the dentist effectively know and apply the necessary knowledge about the correct use of that unit. Only having a good dental treatment unit is not a guarantee that the dentist will work on a correct posture. Therefore, the learning/teaching process in ergonomics is determinant to adopt a healthy work posture [28]. A good ergonomic training during the university studies on the preclinical phases and initial clinic is essential, so that the student learn to identify and adopt a healthy work posture. The use of the proprioception mechanism is fundamental, so that the dentist can effectively develop and adopt a correct work posture [4, 57]. The proprioception is the capacity to recognize the position in space of each part of the body. It results from the interaction among the muscles to keep the body position, the tactile information and on the vestibular system, found on the internal ear, responsible for the equilibrium. The proprioception mechanism works automatically as part of the chain of reflexes to keep the body balanced and organizing the movements. It can be used to recognize and locate the problems and adapt the posture [4, 57]. The healthy work posture is not a condition preprogrammed by the proprioception, and it does not occur without a conscious learning. Learning and training are necessary to get the adequate posture, starting by determining the aim to a physiologically acceptable posture, understanding how to reach that and then executing the necessary actions, followed by a training at the mirror for feedback, or using a biofeedback equipment [4]. To consciously use of the knowledge about proprioception is  only possible during the preclinical training, where low complexity work is being performed, which allows the student to concentrate on the ergonomic training, without having to worry with the result of the procedure itself. On this initial phase, the student has not established bad postural habits, which will lead the body to find alternative postures to keep balance. Because of that, it is important that the dental schools prioritize the teaching of ergonomics at the preclinical phase or at the initial clinical phase.

It is known that the constant force during the pinching movements of the fingers and the extreme movements of the hands, used simultaneously, can produce the carpal tunnel syndrome. On the other hand, the damage can be completely avoided with the preventive elimination of the causal factors, which must be recognized and identified early. Therefore, aiming to prevent those lesions, some measurements can be taken. The first would be to give preference to instruments with thicker handles (. Fig.  4.5), which diminishes the need to a strong pinching to hold them tightly. The habit constantly to hold the instrument strongly should also be avoided, because it results on unnecessary fatigue and incorrect control of the hands. The correct attitude is to hold the instruments gently, only squeezing when necessary to perform an active movement, reducing the force right after to relax the muscles. The extreme movements of the hands should also be avoided, because the displacements of the tendons that are compressed during those movements compress the median nerve causing damages. The arm should turn around its fulcrum, using as rest place the surface to be instrumented, avoiding the excess digital work or the turning of the hand. Regis Filho et al. [53] confirm on their study that most dentists use instruments that do not follow the ergonomic requirements and execute procedures inadequately, among other factors, being submitted to adverse work conditions, where pain and discomfort are present. Hokwerda and Shaw [26] recommend that the dentist should adopt a more dynamic posture of work. According to the authors, the problem with the dentist’s work posture is the static nature, while the human body is supposed to be in constant movement. During the dynamic movement, the muscles act as bomb for the blood supply, with high levels of oxygen, and removal of blood with residual products from the metabolic activity of the muscles. The movement is necessary to recover the distended muscles by the static work. Therefore, the dentists must keep a more dynamic work model, as, for example, the incorporation of the most movements as possible in his activities. The different activities can contribute to that [26, 28]: 55 Adopt a dynamic way to seat alternating between active and passive seating. 55 Use various positions the maximum as possible. 55 Receive personally the patients at the waiting room. 55 Always possible, to work standing up or sitting down alternately. This requires an office with adjustable heights of the patient’s chair and delivery unit. In addition, it is also possible to give instructions to the patient on a standing up position. The computer work can also be done on a standing up position, if it is organized for that. 55 The installation of a sink on an adequate distance from the head of the patient, so it is always necessary to stand up and walk to the sink. 55 The planning of the short procedures should be alternated with the long ones. 55 Schedule short intervals during the treatment, when small exercises can be done, as flexion of the fingers, deep breathing, and stretching (more details later on). 55 Take short intervals between treatments, also taking stretching exercises.  

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55 Take longer breaks, for coffee, tea, and lunch. Take at least 10 min of break after each two hours of work. 55 To keep or maintain the muscles in good conditions by doing exercises at least twice a week. 55 Plan short or long vacations, courses, etc. every 6 weeks. The dental profession is very hard, so it is essential to schedule regular breaks. It is proven that adequate leisure and sport activities reduce stress. 55 Do not work more than 8 h/day. Other indispensable factor to allow a healthy work posture is the use of dental treatment unit that has the ergonomic requirements. Significant changes on the concepts changed the design of dental treatment units, which allow the work on a more ergonomic way. It is important to know how to adopt a healthier work posture and know how to recognize the ergonomic requirements when purchasing a new  dental treatment unit [25, 26, 28, 33]. The market for dental units is regulated by the demand, and this means that the dentists need to claim for units that allow an adoption of a healthy posture. The treatment of WMSD must be multidisciplinary, so the doctor identifies the alteration and coordinates the treatment, the physiotherapist  uses exercises to rehabilitate the compromised movements, the occupational therapist verifies if the work environment needs to be changed, and the psychologist or psychiatrist detects the causes or factors like anguish and anxiety at the work environment [1]. To avoid fatigue, tiredness, and stress, the dentist can follow the checklist presented on 7 Box 2.1 [19, 26, 28].  

>> The carpal tunnel syndrome can be avoided with the preventive elimination of the causal factors; such as giving preference to instruments with thicker handles; eliminating the habit to strongly hold the instrument; and avoiding extreme movements of the hands.

Box 2.1  Ergonomic Check List for a Good Dental Practice (According to ESDE Document) [28]

 rgonomic Check List E 1. Legs perpendicular to the ground. 2. Feet soles on the ground, while the pedal is positioned in a direction in which the feet does not need to be directed sideways during the operation. 3. The angle between the thigh and the lower part of the leg is greater or equal to 110°, in a way that the knees are slightly below the hip level (just if there is an adequate stool with double inclination or a saddle stool). For the regular stool this angle must be 90°. 4. Forearms slightly elevated at least 10° to the maximum of 15°. 5. Arms ahead at maximum of 20°. 6. Elbows next to the body and not far more than 20° sideways. 7. Symmetrical sitting position with the shoulders lowered and relaxed. 8. Avoid torsion of the torso and pressure the intervertebral discs of the column.

9. Avoid forward flexion of the vertebral column. 10. Keep the legs slightly separated (between 35° and not more than 45°). 11. Do not keep the neck bent or pulled. 12. Rest the back on the upper part of the pelvis. 13. Oral cavity of the patient from 5 to 10 cm above the height of the dentist’s elbows. 14. Distance from 30 to 40 cm from the operator’s nose and the patient’s face. 15. Head leaned forward not more than 20°. 16. Operating field well-illuminated and on the medium line of the dentist. 17. The back of the patient’s chair is positioned lying down to allow the operator to freely move the legs under the back of the chair. 18. Avoid sudden movements and forces that cause heavy stress of short duration. 19. Change posture and perform movements. 20. Limit the duration of any continuous muscular strength, preventing muscular exhaustion. 21. Take short and frequent breaks. 22. Take a well-accommodated position at the seat of the stool, in a way that it supports the whole weight of the body. 23. The head of the patient is rotated accordingly in three directions (backward or forward, leaning to the right or left, and turned on the longitudinal axis) in a way that the operating field is positioned symmetrically in front of the dentist’s thorax. That allows to look into the mouth or to the mirror as perpendicularly as possible. 24. The dental light must be as parallel as possible to the line of sight, at a 15° angle, with the light being positioned to the left or the right, very close to the side and above the dentist’s head. When an intraoral mirror is necessary, the light must be positioned slightly in front of the head. 25. Instruments need to be grasped with the tip of the first three fingers, which must be arched around the instrument, in a way to reach three contact points, and the fourth and fifth fingers must be used to rest on the mouth. If necessary, one finger of the inactive hand is used for help the rest. 26. The instruments must be positioned at the same height to the patient’s mouth, as much as possible inside the visual field of the dentist (30° to the left and right). The hand instruments must be positioned at a distance of 20–25 cm and the handpieces at 30–40 cm.

2.4

 xercises to Prevent Osteomuscular E Problems

The stretching exercises can be done at the office, during intervals between sessions, to obtain flexibility of the articulations, improving the circulation and loosening the tense areas, preserving the health, and optimizing the quality of life of the practitioners. They are recommended for prevention of tenosynovitis, tendonitis, synovitis, myositis, fasciitis, ­epicondylitis, paralysis of the upper limbs, and tingling of the hands. During the stretching the dentist must be alert not to pass the expansion limit of his muscle, to hold the exercise for 10 s and to avoid postural compensations of bad positioning during the exercise. Each stretching must be repeated three times, alternating the sides (. Figs. 2.24 and 2.25).  

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a

b

2

c

..      Fig. 2.24  Stretching for the back, shoulders, chest region, arms, and neck. a Stretching of the arms. With the arms raised above the head and palms of the hands together, stretch out the arms upward and a little to the back. Breathe in while stretching upward. b Stretching of the arms and thorax. Interlace the fingers, turn the palms outward, above the head, and extend the arms. Stretch, this way, the arms and thorax. c Stretching of the arms. Interlace the fingers, extend the arms in front of yourself with the palms facing outward. Feel the stretching of the arms and on the upper back. d, e Stretching of the arms. With the arms extended above the head, hold the elbow of one of the arms with the hand of the other arm. Pull kindly the elbow behind the head. Stretch both sides. f Stretching of the shoulders. With the fingers interlaced behind the head, keep the elbows facing outward, wide open, keep the torso erect. Push the elbows backward, one toward the other. Keep the feeling to liberate the tensions for about 8–10 s, then relax. g, h Stretching of the arms. Hold the right arm right above the elbow with the left hand. Now pull slowly the elbow on the direction of the left shoulder while looking over the right shoulder.

d

Keep the stretching for 10 s and repeat the other side. i Stretching of the chest. This stretching must be done with the fingers interlaced behind the back. First, slowly roll up the elbow inward while the arms extend. Second, elevate the arms behind the back until you feel the arms, shoulders and chest stretching. j Stretching the back. Stand up with the feet apart about the same distance of your shoulders and feet pointing forward. Keep the knees slightly bent, put one of the hands on the hip for support and the other arm extends over the head. Now lean to the side in the same direction as the hand on the hip. Come back slowly and keeping the control. k Stretching of the arms. Instead of using the hand on the hip for support rise both arms above the head. Hold the right hand with the left one and bend slowly to the right side, using the right arm to gently pull the left arm above the head and later downward, toward the ground. Using one arm to pull the other is possible to intensify the stretching. l–o Stretching of the neck. Turn the neck slowly and in case you feel a greater tension in any position keep there for 10 s

71 Ergonomics Principles Applied to the Dental Clinic

e

f

g

h

i

..      Fig. 2.24 (continued)

j

k

2

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l

m

n

o

2

..      Fig. 2.24 (continued)

a

..      Fig. 2.25  Stretching for the hands and wrists. a Stretching of the flexor muscle. Start the exercise with the palm of the hand facing downward, extending the right arm. Put the left thumb over the dorsal side of the fingers and the other four fingers over the palm side of the fingers for support. Stretch the flexor muscle group pulling the fingers backward (dorsal flexion). Keep this position for 10 s and then let it go. b Stretching the external side of the forearm. Stretch the external side of the forearm and keep the arm at this position, with the palm of the hand facing downward. Put the four fingers of the left hand over the dorsal surface of the right wrist. Bend the whole hand inward. Keep this flexed position for 10 s. c Stretching of the wrists. Interlace the fingers of both hands and extend both arms in front of you. Turn the hands interlaced to the left, having the wrists as the fulcrum of the movement. After, turn to the right. Each rotation must take 5 s. Turn first to the left

b

and then to the right, repeating every series 3 times. d–f Stretching of the wrists. Open the hands and touch them in “praying” position. With the fingers together, compress one hand with the other in a way that the forces are concentrated on the wrists. Lean the palm of the hand in the direction of the arms. Repeat to the other side. g–i Stretching of the fingers. Open the fingers the farther as possible. Close the fingers squeezing them with the hand extended. Squeeze the fingers against each other, stretching them one by one. It can be done with all the fingers at the same time. j Stretching of the fingers. Squeeze the thumb against the other fingers of the hand, one at a time. k Stretching of the fingers. Cross the fingers and thumbs, one by one, each finger forming a hook. l Stretching of the fingers. Close the hands tightly as they are holding something strongly. After open them and stretch the fingers well. After, put the arms down and swing them, rotating to the sides

73 Ergonomics Principles Applied to the Dental Clinic

c

d

e

f

g

h

i

j

..      Fig. 2.25 (continued)

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k

l

2

..      Fig. 2.25 (continued)

>> The stretching exercises can be done at the office, during intervals between sessions, to obtain flexibility of the articulations, improving the blood circulation and loosening the tense areas, preserving the health, and optimizing the quality of life of the practitioners.

2.5

 urrent Panorama of Dental Ergonomic: C Challenges, Proposals, and Goals

The international literature reveals that the practice of the dental profession needs more use of the existing ergonomic knowledge. To change this picture, it is needed the implementation of a vast program to stimulate the application of ergonomics in dentistry. This program must embrace actions in every sector of the dental system, in a way that there is an effective participation on the dental schools and representative associations of dentists, such as Federal and State Dental Boards, Unions, and any other Dental Associations. It is necessary that parameters should be defined and strategies should be created, to allow the adequate teaching of ergonomics on dental courses and that this information would be applied when building clinics and preclinical laboratories, which allow students and clinicians to work at a healthy posture. The manufacturers of  dental treatment unit and their ­representative associations need to stimulate the constant search and improvement of the unit, and their suitability to the ESDE document [28]. It is important that dental treatment unit manufactures promote ergonomic studies in their  ­laboratories and in conjunction with  the egnonomic’s research associations. The companies should be stimulated to commit part of their incomings to the development of ergonomic research, and to create manuals that promote the adequate use of the dental treatment unit, because only to  manufacture a ergonomic unit does not guarantee that they will be used in an ergonomic way.

The dental schools should promote the development pedagogical strategies that are more efficient to allow the proper teaching of ergonomics. The student must be stimulated to appreciate and to take a healthy work posture since the first work, performed in laboratory or preclinical and, later on, the clinical activities. The current knowledge of ergonomics must be spread out on the various specialties, through manuals of ergonomics that serves as the base for the students and for the professors of every area. The clinicians must be stimulated to select and to buy dental treatment unit that satisfy the ergonomic principles, and to know the cost benefit relationship when taking their decision. Only with the effective and integrated participation of all those sectors, of this complex dental system, will  be possible to implement the necessary improvement of the dental work conditions. >> The dental schools should promote the development of more efficient pedagogical strategies to allow the proper teaching of ergonomics. Students should be strongly encouraged to understand and value the importance of adopting a healthy work posture as soon as possible, ie, from the first procedures performed in mannikin and during the procedures performed in patients at all clinics during the dental course.

Conclusion The working position in dentistry is essential to protect the dental team health. In this chapter, the correct way of ergonomically seat during the dental treatment and properly position the patient in the chair was explained, as well how to grasp the instruments and rest the fingers in the oral environment. The control of the environmental condition in order to protect the health was explained. The exercises that can be done inside the dental office were shown, helping to prevent the most common work-related musculoskeletal disorders.

75 Ergonomics Principles Applied to the Dental Clinic

References 1. Barbosa M, Marques JA, Muse JO. Odontologia em debate: Ergonomia e as doenças ocupacionais. Feira de Santana: Universidade Estadual de Feira de Santana; 2003. 2. Barros O. Ergonomia. 2nd ed. São Paulo: Pancast; 1999. 3. Bauman FS. Giving occupants what they want: guidelines for implementing personal environmental control in your building. World Work 99. Los Angeles; 1999. 4. Belenky M. Human-centered ergonomics: proprioceptive pathway to occupational health and peak performance in dental practice. In: Murphy DC, editor. Ergon Dent care Work. Washington, DC: Am Pub Health Assoc; 1998. p. 275–99. 5. Brandimiller PA. O corpo no trabalho. Guia de conforto e saúde para quem trabalha em microcomputadores. 2a. J.  Bras. Clínica Odontológica Integr. São Paulo: Editora Senac, 1999. 6. Camacho Perdomo JE. Ministério da Saúde. Colômbia: Universidade de Antioquia; 1984. 7. Chasteen JE.  Four-handed dentistry in clinical practice. 1a ed. St. Louis: Mosby; 1978. 8. Chasteen JE.  Essentials of clinical dental assisting. 4 ed. St. Louis: Mosby; 1989. 9. Coelho ACC. Análise de ruídos em laboratórios e clínicas de prótese dentária. [Bauru]: FOB – USP; 2003. 10. Coster EA, Carstens IL, Harris AM. Patterns of stress among dentists. J Dent Assoc South Africa. 1987;42:389–94. 11. Couto H, Lech O. Gerenciando a LER e os DORT nos tempos atuais. Belo Horizonte: ERGO Editora; 2007. 12. Delleman NJ, Haslegrave CM, Chaffin DB.  Working postures and movements. Tools for evaluation and engineering. 1st ed. London: CRC Press; 2004. 13. de Bruyne MAA, Van Renterghem B, Baird A, Palmans T, Danneels L, Dolphens M.  Influence of different stool types on muscle activity and lumbar posture among dentists during a simulated dental screening task. Appl Ergon. 2016;56:220–6. 14. Eero Kerosuo L.  Self-reported health complaints among general dental practitioners, orthodontists, and office employees. Acta Odontol Scand. [Internet]. 2000;58:207–12. https://doi. org/10.1080/000163500750051755. 15. Europäische Gesellschaft für Zahnärztliche Ergonomie  EGZE.  Techinische Berichte: Nr. 10  - 12. Landdruckerei Späthling. Weissenstadt; p. 96. 16. Fernandes JC, Oliveira JR, Fernandes VM.  Avaliação do Ruído em Consultórios Dentários. XI SIMPEP. Bauru; 2004. 17. Ferreira RC. Cargas de trabalho em odontologia e formas de prevenção – Guia curricular para formação de atendentes de consultório para atuar na rede pública do SUS. Área Curric. I, Cargas Trab. Brasilia; 1998. 18. Finocchiaro JA, Aassaf DL, Finocchiaro M. Manual de Prevenção das Lombalgias. Lex Editora; 1978. 19. Genovese W, Lopes A. Doenças Profissionais do CD. 1a ed. São Paulo: Pancast; 1991. 20. Grandjean E. Manual de ergonomia: adaptando o local ao homem. 2nd ed. Porto Alegre: Bookman; 1998. 21. Guidi D, Fichman DM, Santos J Jr. A auxiliar odontológica. São Paulo: Editora Pedagógica e Universitária; 1977. 22. Guiton AC. Tratado de Fisiologia Humana. Rio de Janeiro: Guanabara Koogan; 1983. 23. Heimstra N, McFarling L.  Psicologia Ambiental. São Paulo: Editora da Universidade de São Paulo; 1978. 24. Henriques DYP, Medendorp WP, Gielen CCAM, Crawford JD.  Geometric computations underlying eye-hand coordination: orientations of the two eyes and the head. Exp Brain Res. [Internet]. 2003;152:70–8. https://doi.org/10.1007/s00221-003-1523-4.

25. Hokwerda O, Wouters JAJ. Zicht op licht. Adviezen en richtlijnen op het gebied van verlichting, optische hulpmiddelen en beeldschermen in de tandheelkunde. Nieuwegein: Movir; 2004. 26. Hokwerda O, de Ruijter RAG, Shaw S.  Adopting a healthy sitting working posture during patient treatment. Center for Dentistry and Oral Hygiene, University Medical Center Groningen, p.  28. 2009. Available at: https://www.­rug.­nl/research/ctm/kenniscentrum/ ergonomie/pdfergonomie/1adoptingahealthysittingworkingpostu reduringpatienttreatment.­( jan2009).­pdf. 27. Hokwerda O, Wouters JAJ. Eindrapportage Sonde project. Nieuwegein: Movir; 2002. 28. Hokwerda O, Wouters JAJ, Ruijter RAG, Zijlstra-Shaw S. Ergonomic requirements for dental equipment. Guidelines and recommendations for designing, constructing and selecting dental equipment. European Society Of Dental Ergonomics (ESDE), editor. 2007. Available at: http://www.­esde.­org/docs. 29. Iida I.  Ergonomic contributions do design. 6th Int Congr Ergon Usability Human-Technology Interfaces Prod Information, Built Environ Transp. Bauru; 2006. 30. Iida I.  Ergonomia: projeto e produção. São Paulo: Editora Edgard Blücher; 1998. 31. ISO 11226:2000. Ergonomics -- evaluation of static working postures. ISO: International Standard Organization, editor. 2000. p. 19. 32. ISO 4073:2009. Information system on the location of dental equipment in the working area of the oral health care provider. 2 Edition. ISO: International Standard Organization, editor. 2009. p. 4. 33. ISO 6385:2004. Ergonomics principles in the design of work system. Int. Stand. Organ. ISO: International Standard Organization. 2004. 34. Kimmel K. Zahnärztliche Praxis- und Arbeitsgestaltung. Ergonomie als Grundlage der Leistungs- und Lebensqualität. Köln: Deutscher Zahnärzte Verlag Däv-Hanser; 2001. 35. Knoplich J. Enfermidades da coluna vertebral. São Paulo: Panamed Editorial; 1986. 36. Laville A. Ergonomia. São Paulo: EPU; 1977. 37. Lopes A, Neto RV. A Síndrome do túnel carpal: Um risco profissional para o cirurgião-dentista. Rev da Assoc Paul Cir. 1994;48:1545–52. 38. Lopes MF. O CD e o DORT – Conhecer para prevenir. 2000. 39. Mandel ID. Occupational risks in dentistry: comforts and concerns. J Am Dent Assoc [Internet]. 1993;124:40–9. https://doi.org/10.14219/ jada.archive.1993.0215. 40. Marshall ED, Duncombe LM, Robinson RQ, Kilbreath SL.  Musculoskeletal symptoms in New South Wales dentists. Aust Dent J [Internet]. 1997;42:240–6. https://doi.org/10.1111/j.1834-7819.1997. tb00128.x. 41. Medeiros U, Riul LF. Riscos ocupacionais do CD e sua prevenção. Rev Paul Odontol. 1994;6:34–43. 42. Melis M, Abou-Atme YS, Cottogno L, Pittau R. Upper body musculoskeletal symptoms in Sardinian dental students. J Can Dent Assoc [Internet]. 2004;70:306–10. 43. Méndez FJ, Gómez-Conesa A. Postural hygiene program to prevent low back pain. Spine [Internet]. 2001;26:1280–6. 44. Ministério da Saúde. Protocolo de investigação, diagnóstico, tratamento e prevenção de DORT. Secretaria de Políticas de Saúde, editor. Brasília; 2000. 45. Ministério da Saúde. Lesões por esforços repetitivos (Ler)/distúrbios osteomusculares relacionados ao trabalho (Dort). Departamento de Ações Programáticas Estratégicas ÁT de S do T, editor. Brasília; 2000. 46. Nogueira DP. Riscos ocupacionais de dentistas e sua prevenção. Rev Bras Saúde Ocup. 1983;41:16–24. 47. Oh J, Zhao C, Zobitz ME, Wold LE, An K-N, Amadio PC. Morphological changes of collagen fibrils in the subsynovial connective tissue in carpal tunnel syndrome. J Bone Jt Surg [Internet]. 2006;88: 824–31. https://doi.org/10.2106/JBJS.E.00377.

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7. Rock I. Perception. New York OSABI, editor. 1987. 5 58. Rucker LM, Sunell S. Ergonomic risk factors associated with clinical dentistry. J Calif Dent Assoc [Internet]. 2002;30:139–48. 59. Rundcrantz BL, Johnsson B, Moritz U. Cervical pain and discomfort among dentists. Epidemiological, clinical and therapeutic aspects. Part 1. A survey of pain and discomfort. Swed Dent J [Internet]. 1990;14:71–80. 60. Santos CMD. Móveis ergonômicos. Rev Proteção. 1999:62–5. 61. Santos Filho S, Barreto SM. Atividade ocupacional e prevalência de dor osteomuscular em cirurgiões-dentistas de Belo Horizonte, Minas Gerais, Brasil: contribuição ao debate sobre os distúrbios osteomusculares relacionados ao trabalho. Cad Saúde Pública. 2001;17:181–93. 62. Varkenvisser JK, Kriekaard JJ. Richtlijnen en adviezen ten behoeve van de werkplek van de tandarts op het gebied van verlichting en optometrie. TNO Rapp nr TM-02-C029 Soesterb TNO Tech Menskd. 2002. 63. Vianna R, Arita ES.  Desempenho Lógico. Rev Bras Odontol. 1989;46:27–31. 64. Vieira SI. Manual de saúde e segurança do trabalho. 1a. Florianópolis: Mestra Editora; 2000. 65. Wagner M. Safeguarding the physical well-being of dentists. J Am Dent Assoc. 1985;110:16–24. ­https://doi.org/10.14219/jada. archive.1985.0302.

77

Cariology Taciana Marco Ferraz Caneppele, Alessandra Bühler Borges, Carlos Rocha Gomes Torres, José Roberto Rodrigues, and Thomas Attin 3.1

Introduction – 78

3.2

Etiology of Dental Caries – 78

3.3

 ole of Microorganisms on the Development on Carious R Lesions – 80

3.4

Importance of the Saliva as a Protecting Factor – 81

3.5

Fluoride Action – 82

3.6

Development of the Carious Lesions – 82

3.6.1 3.6.2 3.6.3

L esions at the Occlusal Surface – 88 Lesions at the Proximal and Cervical Third of Smooth Surfaces – 91 Lesions at the Root Surface – 91

3.7

Caries Diagnosis – 93

3.7.1 3.7.2

 ethods for Detecting and Diagnosing Dental Carious Lesion – 95 M Secondary Carious Lesions – 110

3.8

Treatment Decision – 112

3.9

ICDAS – 113 References – 119

© Springer Nature Switzerland AG 2020 C. R. G. Torres (ed.), Modern Operative Dentistry, Textbooks in Contemporary Dentistry, https://doi.org/10.1007/978-3-030-31772-0_3

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Learning Objectives

3

The learning objectives of this chapter are related to the following topics: 55 Carious should be understood as a disease starting already before a cavitation appears. 55 Lesion progression is dependent on the caries risk of the patient and may vary within individual lifetime. 55 Decision about how to treat carious lesions should be based on the knowledge of the individual caries risk. 55 The final goal of the caries disease treatment is to achieve an oral environment, in which demineralized areas may remineralize and in which no new lesions will appear in the future.

3.1

Introduction

Since the beginning of the history of dentistry, the treatment of the dental caries has been focused on the restorations of the cavities using many techniques and materials, which have presented a great evolution throughout time. However, patients still presented the development of carious lesions at the margins of the restorations, called secondary caries, as well new lesions on other dental surfaces. This happened because the secondary caries was being considered to be a distinct entity, closely related to the quality of the restorative material and restorative technique. Nowadays, the secondary caries is considered only a reflex of the caries disease that was not completely treated, confirming the importance of the knowledge of its etiopathogenesis so that it is possible to establish its proper prevention, avoiding the appearance of new lesions [27]. Therefore, the incorporation of the knowledge coming from the cariology must be considered as the base for the success of the restorative treatment [27]. The treatment of the dental caries, which historically based itself only on the reparation of the damage, is considered, nowadays, unacceptable. The modern vision is that the dental caries is a bacterial disease that produces the destruction of the dental organ, causing lesions that are nothing more than the clinical signs of its presence. Therefore, the treatment of the disease must precede the treatment of the signals. In any other way, the lack of success of the treatment surely will happen. >> Dental caries is a bacterial disease that produces the destruction of the dental organ, causing lesions that are nothing more than the clinical signs of its presence. The treatment of the disease must precede the treatment of the lesions.

biofilm, there are some that are capable to metabolize those carbohydrates and besides reproduce themselves; they produce a large quantity of acidic substances that come in contact with the dental structure. The dental enamel is essentially built of hydroxyapatite, which is also present in the dentin, and it is susceptible to dissolution when there is a high quantity of acids in the biofilm fluid and the pH is below a level considered critical (pH = 5.2–5.7). On those cases, the concentration of calcium (Ca2+) and phosphate ions (HPO42−) in the biofilm fluid becomes lower than to the product of solubility of the hydroxyapatite, promoting a physical and chemical tendency of the enamel to loose Ca2+ and HOP42− to the oral environment, at the attempt to reach a new state of balance in function of the reached pH.  This phenomenon is called demineralization. However, a drop of the quantity of fermentable carbohydrate in the oral cavity may reduce microbial activity, bringing back the “normal” status with the biofilm fluid being oversaturated with calcium and phosphate ions in relation to the dental structure. This means that the calcium and phosphate concentration in the biofilm fluid is higher than the product of solubility of the hydroxyapatite. As a consequence, remineralization or at least reparation will occur since those abounded minerals tend to be reincorporated into the dental hard tissue as a phenomenon called remineralization [27]. If there are more periods of remineralization than demineralization, the dental structure keeps itself intact. However, in the cases, in which the periods of demineralization prevail in relation to the periods of remineralization, the structural loss increases gradually, resulting on the presence of cavities, known as carious lesions (. Fig. 3.1). The cycles of demineralization and remineralization are influenced by many determinant factors, which turn the caries a multifactorial disease. Basically, for the development of a carious lesion, three factors are essential, and they are the host (tooth), microbiota, and diet (substrate). Many studies demonstrated that the caries does not develop in animals completely without bacteria [74] nor in animals with oral  

remineralization pH Ca++ HPO4--

Ca++ HPO4-pH demineralization

3.2

Etiology of Dental Caries

It is a proven fact that the caries disease occurs only in individuals with a diet rich in fermentable carbohydrates, especially sucrose. Among the bacteria present on the oral

enamel

biofilm

saliva

..      Fig. 3.1  Schematic drawing explaining the demineralization and remineralization process that happen on the tooth surface due to the pH oscillation of the oral environment

79 Cariology

bacteria but that are fed with a cariogenic diet through stomach canulas [53]. It is evident that only the existence of the three factors happening simultaneously does not result in an instant mineral loss, but it is necessary that they interact for some time, making time to be the fourth important factor. Those factors have been called primary determinants for the caries disease because they are essential to the process of the development of the lesions [71, 75]. . Figure  3.2 illustrates the relation between the dental biofilm and the multiple biological determinants that interfere on the probability to develop a carious lesion. On the internal and interlaced circles, the primary determinant factors for a carious lesion to occur are represented. They are the susceptible dental structure, cariogenic microbiota, the substrate for the microorganisms, and time, so that the demineralization can occur. In relation to the tooth structure, it represents the element which will be attacked in the presence of the caries disease. The age of the patient determines the stage of tooth eruption and the resistance of the teeth against the demineralization, because of the presence or absence of posteruptive enamel maturation. The presence of fluoride on the oral cavity turns the tooth more resistant to the acidic attack and allows better remineralization, while the dental  

morphology may or may not aid the retention of the bacteria on the surface. In relation to the microorganism, the types present also have great influence because the existence of the acidogenic and aciduric bacteria is essential for the process. In addition, the adequate dental hygiene may result in the disorganization of the biofilm, reducing the quantity of acids produced. Depending on the concentration of fluoride on the biofilm, the metabolic activity of the bacteria may also be diminished. In relation to the substrate, the composition and frequency of the diet favors or not the bacterial activity, so it is also a decisive part of the process because they are the nutrients so that the bacteria survive on. The adequate oral hygiene habits can remove the food residues, reducing the substrate available. In relation to the time, due to the diet with high consumption of fermentable carbohydrates, there is a variation of pH that leads to mineral loss. It is necessary that this interaction is kept through some time so it results in the formation of the incipient lesions initially and later on the cavitation. In the light blue circle, the secondary main determinant factor is presented, which is the saliva. It is saturated in calcium and phosphate and participates in the processes of demineralization and remineralization. Its compositions, the

SCHOLARITY SOCIAL CLASS

KNOWLEDGE SALIVA (COMPOSITION, FLUX, BUFFER CAPACITY)

TIME

TOOTH (AGE, FLUORIDE, MORFOLOGY)

CARIOUS LESION

MICROBIOTA (TYPE, QUANTITY FLUORIDE, HYGIENE)

SUBSTRATE (COMPOSITION OF DIET, FREQUENCY, HYGIENE)

SALIVA

ATTITUDES

INCOME

BEHAVIOR

..      Fig. 3.2  Schematic drawing of determinant factors for caries disease. On the internal interlaced circles, the primary determinant factors are given. On the light blue circle, the secondary determinant

factor, while on the dark blue circle the confounding factors are depicted. (Adapted from Fejerskov and Manji) [26]

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salivary flow or flux, and its capacity to neutralize the acidity by the buffering effect have a great influence on the occurrence or not of those lesions. On the dark blue circle, the factors that are not decisive for the disease but are tied to it in some way are presented. They are called “confounding factors” because they do not always influence on the same way in all societies, although the determinant factors will certainly always be the same in all populations [26]. As examples are the social class, the financial income, and knowledge, which can allow greater access to information about the causes of the disease, besides the monitoring by a clinician. In addition, the behavior and the attitudes will favor that the patient has healthy dietary and hygiene habits. 3.3

Role of Microorganisms on the Development on Carious Lesions

Keyes [52] investigation, at the beginning of the 1960s decade, demonstrated the need of a specific microbiota for occurrence of the dental caries. The researcher verified that the hamster babies, which the mothers had been treated with antibiotics during the breastfeeding period, did not develop carious lesion, even receiving a diet with a great cariogenic potential. Those “not contaminated” babies only developed lesions when in contact with infected hamsters, or when inoculated with material provided from the biofilm of those animals. Until the decade of 1960, it was believed that the caries disease was the result of the collective production of acids by the acidogenic bacterial communities on the biofilm. This way of seeing the process was called the “non-specific plaque hypothesis.” However, later studies demonstrate that the members of a colony of hamsters without caries but that had a microbiota composed by numerous acidogenic microorganisms only developed caries when contaminated by specific Streptococcus, which came from lesions from hamster that had active caries and were submitted to a diet rich in sucrose [30]. Those microorganisms, later identified as mutans group streptococci, are cariogenic by nature and present a potential to produce carious lesions much higher than any other acidogenic microorganism on biofilm. Since those first studies until today, many researches have demonstrated the role of this group of microorganisms on the etiology of the caries. The biofilms removed from the areas with cavities are bacteriologically and biochemically different from those coming from a healthy zone, proving that there is a more specific microbiota on the development of the carious lesion [55]. Those observations gave origin to the “specific plaque hypothesis.” It helps to explain the results of an epidemiological study, performed in 2001, in the United States, when 60% of the carious lesions happened in only 20% of the analyzed population, while only 5% of the population was caries free [90]. In . Fig. 3.3, the disclosed bacterial biofilm can be seen in a patient with high caries activity. These findings changed some concepts from the 1950s when it was believed that Lactobacillus was the main suspect for the initiation of the carious lesions, due to its  

..      Fig. 3.3  Disclosed bacterial biofilm

capacity to produce acid and presence in high amounts on patients with high caries experience. However, the studies of the microbiota of the biofilm demonstrated that Lactobacillus represents only a reduced fraction of the total microorganisms present on the biofilm, and it was impossible to claim that they were responsible for the presence of carious lesions. In addition, they had a low adhesive capacity to the acquired salivary pellicle. On the other hand, streptococci species with a high cariogenic potential were numerically much more significant on the biofilms that appeared right before the initial carious lesions, keeping a relation of 10,000:1, in relation to the Lactobacillus. Additionally, streptococci presented a much higher adherence capacity to the tooth surfaces. Nowadays, there is great evidence that the mutans group streptococci play an important role in the initiation of human caries. They are highly acidogenic (capable to produce acids) and acidurics (capable to live in an acidic environment), and its cariogenic potential is well established in animals. They preferably colonize the teeth, and they are found in high proportions in the grooves, fissures, contact areas, and other retentive zones, in a way that its pattern of colonization happens in parallel with the areas that are susceptible to caries [36]. The lactobacilli are, usually, found on the carious lesions that already have cavitated, and its number at the saliva generally maintains a positive correlation with the caries experience. On the other hand, the rigorous restraint to the consumption of sugars, in general, decreases significantly the caries activity and the number of Lactobacillus in the saliva [48]. However, as it has already been described, everything seems to indicate that the lactobacilli are not essentially involved at the initiation of the caries, acting mostly as “secondary invaders” that take advantages of the acidic conditions and the retention that prevails inside the carious lesion. This fact is corroborated by the observation that lactobacilli are usually not detected in biofilms that cover incipient caries. At these conditions, the detection of a high concentration of Lactobacillus in the saliva (>100,000/ml) would work as an excellent indicator of risk for progression of initial preexisting caries. This indicator may have an important function in

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the decision to treat, restoratively or not, incipient caries, especially in cases of interproximal caries detected by radiography, and that does not allow a clinical evaluation of the presence or absence of cavitations [76]. Under common circumstances, without the exaggerated consumption of sucrose, as it happens in isolated populations that do not have access to the modern diet with processed food, the microbiota that colonizes the teeth presents low cariogenic potential. The dental surface can be seen as a habitat to be colonized. As soon as the teeth erupt, the pioneer bacteria, which produce extracellular polysaccharide capable to adhere to the surface, will bond to the salivary pellicle. They start to reproduce, forming an initial bacterial biofilm, so they are considered pioneer bacteria. Among them, streptococci from the oralis group are present, which are aerobic bacteria (e.g., Streptococcus sanguinis, Streptococcus mitis, and Streptococcus oralis). Those bacteria modify the environment and allow that the biofilm becomes attractive for other bacteria to live in, turning it more complex. In each interval, the conditions of the environment change in a way that can favor or disfavor the presence of certain bacterial group. After a determined period, the biofilm reached its maximum degree of maturity. The observation of this ecological sequence of microorganisms gave origin to the so-called ecological plaque hypothesis. The first ecological microbial succession happens after the teeth erupt, and it is called the primary succession. However, every time the bacterial biofilm is disorganized or completely removed by brushing, it will develop itself again, through a new ecological succession, called the secondary succession. On the other hand, every time an ecological succession occurs, the conditions of the environment may favor or disfavor the development of a certain group of microorganisms. One example of that happens in individuals with low caries activities that for some reason begin to consume a high quantity of sucrose and to neglect the oral hygiene. On those cases, the acidogenic bacteria, as the mutans group streptococci and the lactobacilli, are starting to produce acid, which will lead to a lowering of the pH of the biofilm. These same bacteria are aciduric and resistant to this environment. However, this hinders that the acidsensitive bacteria as the Streptococcus from the oralis group to develop, and its quantity is drastically reduced. The capacity for the acidogenic and aciduric bacteria to perform a natural selection during the ecological succession allows them to be called pH strategist [13]. Some studies demonstrate that the chance of an individual to develop a pathogenic biofilm is lower when the primary ecological succession occurs in a low consumption of sucrose and the first colonizing bacteria are not being cariogenic. Therefore, some members of a dental biofilm are considered beneficial for the host, because they may play a role of a protector against the colonization of exogenous species or even to produce substance as bacteriocins, surfactants, and hydrogen peroxide, which have antagonist effects on the establishment of the Streptococcus mutans and Lactobacillus [42]. This prevention is called primary or true prevention.

3.4

I mportance of the Saliva as a Protecting Factor

Saliva is a glandular secretion with a complex composition presenting organic and inorganic components. The organic components consist of a variety of proteins, carbohydrates, and enzymes, each one having an important function of control of the oral environment. The inorganic components, such as sodium, potassium, calcium, chlorite, bicarbonate, and phosphate, determine the relative saturation of the fluid in relation to hydroxyapatite. Other than those inorganic components, many cellular elements are found in the saliva, especially epithelial cells peeled from the mucosa, leukocytes, and neutrophils originated from the gingival sulcus, besides microorganisms [75]. Saliva is present during the development of carious lesions, influencing in an important way the process of tooth decay. A study showed that an extreme deficiency of saliva results in an increase of the cariogenic activity [33]. The saliva acts actively on the process of demineralization and remineralization of the dental hard tissue, through the ionic exchange of Ca2+ and HPO42− with the biofilm and dental mineral structure. Saliva presents a buffering capacity, which is the capacity of the saliva to keep its pH constant between 6.9 and 7.0. Due to its mucinate/mucin, bicarbonate/carbonic acid, and monophosphate/bisphosphate buffers, it counteracts the excess of acids or bases, neutralizing the acids formed by the bacterial metabolism [91]. Other important protector role of the saliva is the mechanical clearance (removing food ­detritus and bacteria) through the saliva flux. Saliva also influences the ecological balance of the oral microorganisms, since it serves as substrate for the bacteria, interferes on the microbial adhesion by the formation of an acquired pellicle, and has antimicrobial substances with immunological (secretory IgA, IgG, and IgM) and non-immunological effects (lactoferrin, lysozyme, lactoperoxidase, and myeloperoxidase) [64]. The non-stimulated salivary flux varies between 0.25 and 0.35 ml/min, increasing from 1 to 3 ml/min when it is stimulated by the chewing. The saliva flux varies during the day, coming to its minimum during sleep, with a minimum of its protector effect, what may additionally explain the appearance of rampant carious lesion in children having a baby bottle with sucrose as a night habit. Some systemic diseases, such as Sjögren’s syndrome, rheumatic arthritis, diabetes mellitus, nervous anorexia, Parkinson disease, and depression, among others, have the side effect of reducing the production of saliva. The use of some medications as antispasmodic, antidepressants, muscle relaxants, antiarrhythmic, antihistaminic, antihypertensive, diuretics, and anti-inflammatory, among others, also reduces the salivary flux. People with reduced saliva flux lack the protective action of the saliva, and so, they are more prone to the development of carious lesion. Some clinical evidence is related to the reduction of the saliva flux, for example, reports from patients about dry mouth, constant thirst, difficulties to talk and to swallow,

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burning and tingling sensation on the tongue, and difficulty to use total or removable prosthetic appliances. Additional clinical signs of reduced salivary flux are oral mucosa irritability, presence of fissures and ulcers on the commissures, red and fissured tongue, and carious lesions on tooth smooth surfaces, usually places of self-cleaning, as the areas above the height of curvature and incisal edge. During the manipulation of the oral cavity, it can also be verified that the clinical mirror or a gloved finger adheres to the dried-out mucosa. 3.5

Fluoride Action

Nowadays, it is known that the cariostatic effect of fluoride is a consequence of its presence on the organic fluids during the cariogenic attack. Because of the pH variation on the oral environment, the dental enamel suffers a process of constant demineralization and remineralization. Fluoride, even in a small concentration, interferes on the cariogenic process. Below pH 5.5 (critical level of demineralization of the enamel), the tooth environment (biofilm fluid) becomes unsaturated with respect to hydroxyapatite. Thus, diffusion of enamel minerals from the tooth to the environment occurs (demineralization) to restore the ionic balance between them. The hydroxyapatite of the enamel starts to dissolve at a pH around 5.3–5.5; However, fluorapatite is not dissolved until the pH is below 4.5. When the oral environment pH is between 5.5 and 4.5, the enamel release calcium, phosphate, and hydroxyls to the oral environment. At this pH range, if fluoride ions are available, the minerals will be able to form fluorapatite and fluoridated apatite, which will deposit on and in the dental enamel. The fluoride presence at biofilm fluid promotes a remineralization without the need for the pH to reverse above the critical pH for hydroxyapatite. Therefore, the availability of fluoride ions for prolonged periods is important, even in low concentrations. The demineralization process will depend on the fluoride concentration on the tooth/biofilm interface and on the pH of the biofilm fluid. The lower the pH of the environment, the higher is the concentration of fluoride needed to hinder the demineralization process of the dental structures. However, there is a limit for the action of fluoride ions. If the pH is below 4.5, the biofilm fluid will become unsaturated with respect to the two apatites (hydroxyapatite and fluorapatite); as consequence, mineral loss will happen [17, 63]. Besides the interference on the process, the demineralization and remineralization, the fluoride interferes on the growth and the bacterial metabolism. Low levels of fluoride can change the metabolism of the carbohydrates by the bacteria, resulting in the reduction of the production of acids and polysaccharides and in the bacterial adherence [39]. At low concentration it presents bacteriostatic effects, but in high concentration, it can have a bactericide effect. When fluoride is applied to the dental surface in concentrations above 100 ppm, in an acidic formulation or with a prolonged contact to the surface, a calcium fluoride-like layer (CaF2) is formed on the surface. That substance per se is not stable in the environment of the oral cavity. However, under

clinical conditions, the surface-deposited CaF2 is covered by phosphate and proteins from the saliva, forming a type of protection. This so-formed calcium fluoride-like layer shows a low dissolution rate, making it to act as a slow fluoride-­ releasing agent. In case of a pH drop in the biofilm, the phosphate and protein layer of the deposit is solubilized, exposing the soluble CaF2. The release of fluoride and calcium to the environment promotes formation of fluorapatite right at the time point of the acidic attack. That means that remineralization directly occurs parallel to the time point of demineralization. When the pH recovers to physiological values, the remaining CaF2 is once again coated and is available to participate in a new cycle of demineralization and remineralization. By this, it can be considered a continuous reserve of fluoride, with an active participation on the dynamic of the development of the carious lesion. In order to keep the deposit of calcium fluoride at a high level, it is fundamental that fluoride-containing products, such as toothpaste or mouthwash, are frequently used. 3.6

Development of the Carious Lesions

With the formation of the bacterial biofilm on the dental surface and in the presence of a diet rich in fermentable carbohydrates, acids will be formed by the bacterial metabolism, which will reach the surface of the enamel, promoting its demineralization. This accumulation of biofilm occurs especially in regions protected from friction with the soft tissues and with the food bolus, as the bottom of the grooves, interproximal regions, and cervical areas of smooth surfaces below the height of curvature (. Fig. 3.11a). Initially, dissolution of the interprismatic enamel is started, with the accentuation of the prism prominences, creating a rough surface with surficial porosities (. Fig. 3.4a). The acids continue to diffuse into intercrystallite water-filled spaces and the process keeps on, following the direction of the enamel prisms. At the surface layer of the lesion, the level of mineral loss is lower than in the more inner regions, due to its contact with the mineral-rich and oversaturated saliva. After some time, an incipient carious lesion is formed in the enamel with a relatively intact surface, with a porosity volume of approximately 1%, called surface zone, and a subsurface porous part, with a porosity volume of 5–25%, called the lesion body (LB). At the deepest inner portions of the lesion, the front of demineralization (translucent zone) is created, with a porosity volume of 1%. At this area the dissolution of the intact enamel prisms is happening. The dissolved mineral salts at this area, before leaching outward, temporarily accumulate on the neighboring region, called dark zone, with 2–4% of porosity. Afterward, the minerals diffuse to the LB and later to the oral environment through the pores in the surface zone. In . Fig. 3.4b, c, the histological aspect of a subsurface carious lesion, pointing out the surface zone (arrow), and the LB is depicted. . Figure 3.4d shows a schematic drawing of the variation of porosities in the different layers of an initial enamel lesion.  

 

 

 

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a

b

c

d

..      Fig. 3.4  a Scanning electron microscopy image of human enamel surface showing on the left a white spot lesion with many pores (arrow), contrasting with the aspect on the right, where the enamel is intact; b histological aspect of an enamel carious lesion observed on the optical microscopy (2.5×); c greater magnification of the lesion

presented in the image b, showing the lesion body (LB) and the surface zone (arrow) (10×); d scheme showing the levels of porosity on the different zones of the enamel lesions (arrow, surface zone; LB, lesion body of the; DZ, dark zone; TZ, translucent zone)

As a consequence of the presence of this subsurface lesion, there is a modification of the optical behavior of the dental structure. According to the laws of optics, when there is a difference in refractive index between two materials, there will be an interface that deviates the light waves [19]. When the enamel is intact, the whole tissue has a refractive index of 1.62 and there are no interfaces. The light travels through the tissue without modification on its trajectory, until it reaches the DEJ, being then reflected back. However, the caries lesion has many porosities filled mainly with water from saliva, which has a refractive index of 1.33. In this case, the light waves reach multiples interfaces between the fluid and the mineral phase, with different refractive indices. At each interface the light is deviated and reflected, becoming imprisoned in an “optical maze” that is over-luminous and therefore perceived as white, creating a so-called white spot lesion [19]. Small subsurface lesions may not be visible when the tooth is wet because the amount of water present on the internal porosity of the lesion may not be capable to deviate the light enough. However, when it is dried with a blow of air, the water inside the porosities is replaced by air, which has an even lower reflection index, equal to 1, making it visible for a naked eye. On the other hand, more advanced sub-

surface lesions are visible even when they are hydrated because of the high amount of water inside. When such a lesion is dried, its visible size becomes even greater (. Figs. 3.5a–h and 3.6a–d). A study correlated the severity of carious lesions and their histological depth. White spot lesions, which require air-­drying, are most likely to be limited to the outer ½ of the enamel. The depth of a white lesion which is obvious without air-drying is located some place between the inner 1/2 of the enamel and the outer 1/3 of the dentin [23]. When dried with a blow of air, active enamel caries lesions present an opaque white, chalky, and dull surface. In contrast, non-active, arrested initial lesions show a glossy white surface after drying. Every effort must be kept on the way to diagnose and stop the lesion yet at this stage. At this moment preventive treatments are mandatory to interrupt and stop the bacteria colonization of the surface and to disorganize the biofilm on the surface. However, if the surface pseudo-intact layer is destroyed and breached, for example, by probing with a dental instrument, a bacterial invasion into the body of the lesion will occur. In such a cavitated lesion control and removal of the biofilm is almost impossible and the lesion is going to progress. This means that a cavitated and not cleanable lesion,  

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a

b

c

d

e

f

g

h

3

..      Fig. 3.5  Teeth with active carious white spot lesions. The clinical aspect is modified when the tooth is wet or dry. a, c, e With the teeth wet and the lesions seem smaller; b, d, f dry teeth showing the real size

of the lesions. g, h White spot lesion on the occlusal surface, with the surface wet and dry, respectively

e.g., at the proximal aspect of a tooth, will be necessary to be filled up with a restoration (. Fig. 3.6a–d). In smooth surfaces, as the mesial, distal, buccal, and lingual surfaces, the carious lesions progress with a cone shape, with the base facing the external surface of the tooth, while at the region of the grooves, due to the inclination of the cuspid, the lesion at the enamel progresses with cone shape with the base facing the dentinoenamel junction (. Figs.  3.7a and 3.8a). When the acids go through the intercrystallite spaces and reach the dentin, even with an intact surface zone of the lesion, the demineralization expands laterally along the DEJ,

forming a second cone, with apices directed toward the pulpal chamber, following the dentinal tubules (. Figs. 3.7b, c and 3.8b). If the surface is still intact, no bacterial invasion into the lesion body will occur, and progression of the lesion might be stopped simply by removing the bacterial biofilm from the surface, allowing its remineralization by the saliva. As soon as the surface zone of the lesion is fractured, it often becomes impossible to remove the bacterial biofilm with common oral hygiene measures, and a restoration is indicated (. Figs. 3.7d and 3.8c, d). With time, all the adjacent dentin is destroyed, and only the undermined enamel is

 

 

 

 

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b

a

d

c

..      Fig. 3.6  a Anterior teeth with great accumulation of bacterial biofilm; b aspect after removal of the biofilm with the surface still wet; c aspect after drying with a blow of air. It can be observed that the white spots are more visible and seem larger than when the teeth are

dry. It can also be verified the presence of cavity on the cervical region on the tooth 12; d sectioned extracted teeth showing the breaking out of the surface zone of a white spot lesion, resulting in a cavity and bacterial invasion in the lesion body

left (. Fig.  3.8d). When the cavity reaches the dentin, the tubules are invaded by the bacteria, and the acids and proteolytic enzymes lead to a liquefaction necrosis process of the outermost layer of dentin (. Fig. 3.8d – Asterisk). Below this very soft layer of liquefaction necrosis, an intermediary demineralized and contaminated layer, called infected dentin, exists. As the penetration of the acids in the tubules precedes the bacterial invasion, a deeper dentin area is already demineralized without the presence of bacteria, called affected dentin. With the progression of the lesion, the contaminated area spreads, and when there is only 0.5  mm of remaining tooth structure covering the pulpal chamber, the diffusion of the bacterial metabolic reaches the pulp and can start an inflammatory reaction, called pulpitis [72]. If ­nothing is done and the process continues, the bacterial invasion into the pulp tissue will lead it to necrosis. In . Fig. 3.9a, and b the clinical aspect of the necrotic dentin being removed with a spoon excavator is depicted. More internally, when excavated, the demineralized and contaminated dentin is removed in chips.

When the enamel carious lesion at the enamel comes close to the dentinal tissue, even before the start of dentin demineralization, the odontoblasts react trying to obliterate the tubules by the deposition of calcium salts inside the lumen, forming the so-called sclerotic dentin (. Fig. 3.7 – red arrows) [50, 89]. This could be interpreted as an attempt to block irritating and aggressive agents from reaching the pulpal tissue. In . Fig. 3.10, the clinical aspect of the sclerotic dentin can be observed at the pulpal wall. It presents an extremely hard consistence to probing and a dark brown or black color. With the lesion progression, the increase of dentin demineralization stimulates the primary odontoblasts in contact with the affected tubules. They start the focal secretion of dentin matrix tissue inside the pulpal chamber, forming a tertiary dentin known as reactionary, which shows tubular continuity with the secondary dentin [46]. With the increase of the injury intensity, the primary odontoblasts will be compromised in terms of survival until cell death. When the pulp defense mechanism is still active,

 

 

 

 

 

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a

b

c

d

3

..      Fig. 3.7  Progression of the carious lesion on smooth surface. a Subsurface lesion limited to the enamel; b, c dentin demineralization without the presence of cavity; d demineralization and disorganization

of the dentin after cavitation. The black arrows indicate the demineralized dentin, while the red arrows indicate the sclerotic dentin

stem/progenitor cells may be recruited to the injury site, creating a new generation of odontoblast-like cells secreting reparative tertiary dentin [7]. In this case there will be a lack of tubule continuity with the secondary dentin, creating a barrier effect that will protect the pulp tissue, until the caries process reaches this region [46]. However, this sequence of events only happens in the cases when the carious lesion has low-speed progression. In patients with high caries activity, the lesions can progress so fast that there is no time for sclerosis and much less for the formation of reactionary or reparative dentin, increasing the risk for development of an irreversible involvement of the pulp. In addition, during cavity preparation of a tooth with a lesion of fast progression, a greater chance of accidental exposure of the pulpal tissue also occurs, due to the higher quantity of softened dentinal tissue. In some special cases, with teeth showing no signs of irreversible pulpitis, it may be advised to restore the not completely carious-free cavity temporarily. This intermediary step may allow remineralization of the affected dentinal tissue, as well as formation of the tubule’s sclerosis and of the reactionary dentin. Further details are provided in the following chapters. When the white spot lesion in enamel is detected before cavitation happens, the treatment of the caries disease by

intensifying preventive measures along with fluoride applications will promote the deposition of calcium salts on the surface and inside the lesion. By this it may happen that small lesions completely disappear. However, once the pores of the surface zone are closed, minerals will not be deposited homogeneously inside the lesion body. Thus, the bigger a lesion is, the more likely it will stay visible, even after being arrested. Clinical studies demonstrate that only 33 to 49% of white spot lesions disappear when being arrested. It is known that white spot lesions become inactive as soon as no biofilm is present on its surface. At this inactive state, white spot lesions present a shining surface when dried with a blow of air (. Fig.  3.11b). During the arresting process, pigments and dyes present in the oral cavity from the diet can deposit into the porosity, changing the white spots to darkish or brownish spots (. Fig. 3.12a, b). The activity of caries disease is related to the interaction between the determinant factors, leading to an unbalance of the demineralization/remineralization process with more mineral loss than gain, due to the production of acids in the biofilm. However, this conjuncture can be changed at any time, and a patient with a high caries activity can be changed to low activity, resulting in an abrupt drop of the acid production. When this happens, the existing lesions, even if  

 

87 Cariology

a

b

c

d

..      Fig. 3.8  Progression of the carious lesion on the occlusal surface. a Subsurface lesion limited to the enamel; b dentin demineralization without the presence of cavitation; c, d demineralization and

disorganization of the dentin after cavitation. The black arrows indicate the demineralized dentin and the asterisk the necrotic dentin

b

a

..      Fig. 3.9  Clinical aspect of carious dentin. a Necrotic dentin with a “porridge” aspect; b demineralized dentin removed in chips

cavitated, change their aspect. The active cavitated lesions of intense acidogenic activity, called acute carious lesion, have a large quantity of bacterial biofilm and a wet appearance, and the dentinary tissue shows a light brown color and is extremely soft (. Fig. 3.13a). Frequently there are white spots on the enamel margins of those cavities. However, in lesions  

of low acidogenic activity, called chronic carious lesions, no biofilm is visible, and the dentin looks dryer, with a darker color and a consistency described as similar to leather (. Fig.  3.13b). In turn, as an acute lesion may become chronic, the opposite may also happen, when the determinant factors of the caries disease may prevail again.  

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3.6.1

Lesions at the Occlusal Surface

Carious lesions located at the occlusal surface of posterior teeth have a higher prevalence than at other tooth areas, as

3

..      Fig. 3.10  Clinical aspect of darkened sclerotic dentin at pulpal wall

a

shown in epidemiological studies [78, 79]. Clinically, it often occurs as a localized phenomenon at one single spot of the groove and fissure system. This happens, since the carious lesion starts on sites where the bacterial growing is more protected against the functional contact and removal [14]. Therefore, two factors have been considered to be important for the growing of biofilm and the onset of a carious lesion at the occlusal surfaces: the eruption stage of the tooth that is related to the functional use of the teeth and the specific anatomy of each tooth [14–16]. Throughout the eruption process of the teeth, up to the occlusal contact with its antagonist, these teeth are more susceptible to caries. Although the dental enamel is completely formed at the time of eruption, it still presents high porosity. It has been suggested that it goes through a posteruptive enamel maturation period after its exposure to the saliva, which will increase its resistance to demineralization [54, 96]. The nature of this maturation is still not completely understood, but it is believed that during this period the mineral ions and the fluoride in the oral environment diffuse into the enamel.

b

..      Fig. 3.11  White spot lesions in enamel. a The presence of lesions is associated to the places where bacterial biofilm occurs, as in cervical and interproximal regions; b inactive lesions with shiny surface

a

b

..      Fig. 3.12  Darkened inactive carious lesion in enamel. a Labial surface; b proximal surface

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a

b

..      Fig. 3.13  Clinical aspect of a carious lesion. a Acute lesions; b chronicle lesions

The partially erupted teeth do not participate in the chewing, since they do not contact their antagonists. Thus, accumulation of a biofilm is more likely. This come together with the fact that a regular hygiene of these teeth with the surface below the level of the other teeth is more demanding [14]. Therefore, bacterial growth can be accentuated at those sites of not fully matured enamel (. Fig. 3.5). As the tooth comes close to the complete functional occlusion, the shearing forces, coming from functional chewing, disorganize the dental biofilm, so that no biofilm is formed on the cuspal incline. However, the bacterial deposits, located in the deepest area of pits and grooves, are still protected against those mechanical removal forces. Therefore, it is observed that the visible signs of the caries develop at places where the bacterial deposits remain protected against the removal oral forces for a long period. One of the reasons for the greater prevalence of carious lesions in molars in relation to premolars is related to the fact that they take longer to erupt, thus staying susceptible for bacterial adherence for longer time. The molars take from 12 to 18 months to come in contact with the antagonist, whereas the premolars take from 1 to 2 months. A correlation between the morphology of the occlusal surface and the caries onset at this area exists. In the past, it was believed that patients with deeper dental grooves were more susceptible to develop lesions than the ones with shallower grooves, since the bristles of a toothbrush would not be capable to clean this region. . Figure 3.14a–f shows the basic types of grooves that can be found in the population. Type 1 represents a shallow and open groove, while Type 2 is a narrow and deep one. Type 3 is the ampoule or bottle-shaped groove, with narrowing at the entrance and an enlargement at the base. Type 4 is a real fissure because there is no coalescence of the enamel from one cuspal incline with the other and there is a direct contact between the environment and the dentin [84]. A pit is a small fault located on the tooth’s surface. It is generally found on the intersection of two fissures or at the end of a developmental groove. However, it was shown that a carious lesion does not begin in the deepest part of grooves, but on the side, next to  

 

the surface (. Fig. 3.15). For the development of the microbiota in the biofilm, it is necessary to have space and nutrition, which is less likely at the bottom of the groove Type 2 (. Fig. 3.14c). Therefore, more important than the depth of the pits and grooves is the form of the occlusal morphology, which may or may not favor the retention of the bacterial biofilm. With increasing tooth wear, teeth will show a smoother surface, reducing the propensity to biofilm accumulation (. Fig. 3.16a–d). It was noticed that this fact reduces the risk of lesion development despite the groove anatomy. Conversely, grooves Type 3, bottle-shaped, are a concern because this morphology allows the growth of the microbiota in its interior (. Fig. 3.14d). However, this fissure type is only seen in 10% of the teeth and is associated with the presence of very high cusps. The presence of real fissures is another problem because it favors the carious lesion to reach the dentin and it has a very fast progression. However, its frequency is even smaller than the other configurations [84]. Real fissures and pits are more common at the buccal groove of the lower molars, where lesions progress into the dentin without external signs, resulting later in lesions like the one observed in 7 Fig. 5.13c. The peculiar characteristics during the developing of carious lesions at occlusal surfaces, shaped as two cones, one over the other, base against base, favor the expansion of the carious lesion under clinically intact enamel. This special feature may result in the phenomenon known as hidden caries lesion (. Fig. 3.17a–c) [12]. Externally, the structure of the enamel is kept intact, or sometimes there is a darkened aspect on the groove, while internally the dentin can be completely compromised and the enamel undermined. Sometimes those patients report pain when chewing and when consuming cold or sweet food. The frequent presence of fluoride in the oral cavity, increasing the resistance of the enamel against demineralization, is regarded as one of the factors that may propitiate the occurrence of hidden caries. In the past, before the intense use of fluorides, the incidence of the hidden lesions was lower, since the demineralized enamel fractured more likely and exposed the cavity. However, the nowadays use of fluorides is effective to keep the enamel around the grooves  

 

 

 

 

 

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b

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..      Fig. 3.14  a Groove types. (Adapted from Roberson et al. [84]); b shallow and large groove; c narrow and deep groove; d bottle-­ shaped groove; e macroscopic aspect of the buccal surface on a

mandibular molar showing a pit at the end of the groove suggesting the presence of a fissure; f existence of a direct connection between the oral environment and dentin, representing a real fissure

and pits stable, thus keeping the dentin lesion hidden. Because of that, some authors describe the great number of hidden lesions found nowadays as the “fluoride syndrome” [12]. Even though the hidden carious lesion can clinically manifest as darkened grooves and pits on the occlusal surfaces, the caries disease by itself is not the only reason for this darkened aspect in those areas. Because of the retentive characteristics of this region, residues coming from the diet, dead bacteria, calculus, and many other dark coloring substances

can deposit and seal those areas (. Fig. 3.18a). This phenomenon is called biological sealing. In . Fig. 3.18b, a transverse cut of a darkened groove shows the presence of deposits, without any evidence of caries. Therefore, the mere presence of a darkened groove should not be considered as a sign for caries.  

 

>> Merely the presence of a darkened groove should not be considered as a sign for caries.

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3.6.2

 esions at the Proximal and Cervical L Third of Smooth Surfaces

The establishment of the proximal contact points hinders the deposition of a bacterial biofilm exactly at this region. However, below the contact area, the bacteria are protected against removing oral forces, and together with a gingival retraction, this place can favor the appearance of clinically

detectable lesions. The shape of the proximal white spot is determined by the biofilm location between the marginal gingiva and the contact area, resulting in a lesion of an elliptic or “kidney” shape. The cervical margin of the lesion is formed following the contour of the marginal gingiva (. Fig. 3.19a– d). On the buccal and lingual surfaces, the deposit of bacterial biofilm happens in the region below the height of contour (crest of curvature), where the friction with the food bolus is not capable to remove it, following the edge of the marginal gingiva (. Fig. 3.20a–c). From the necessity of intervention point of view, lesions of smooth surfaces should not be treated in an invasive approach as long as they are not cavitated. Those lesions may arrest if the bacterial biofilm is regularly disorganized and eating habits are changed. On the buccal and lingual surfaces, the direct vision allows an easy decision, and it is only mandatory that the surface is perfectly clean. However, at the proximal surfaces, the verification of surface integrity is more difficult.  

 

3.6.3

..      Fig. 3.15  White spot lesion progressing at the side of the groove

Lesions at the Root Surface

The retraction of the gingival margin is a consequence of an inadequate oral hygiene and the loss of the periodontal insertion happening with age. As the gingival margin retracts, the

a

b

c

d

..      Fig. 3.16  Occlusal macro-morphology. a, b Irregular surface that favors the deposit of biofilm; c, d worn teeth impairing biofilm deposition

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..      Fig. 3.17  a–c Hidden carious lesion with a minimal superficial opening and large cavitation in dentin

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..      Fig. 3.18  a Darkened grooves by deposit of pigments; b biological sealing inside the groove

enamel-dentin junction becomes exposed. This tooth region is very irregular and represents the propitious area for bacterial accumulation. Consequently, most of the root caries start at this area [25]. Root exposure, especially in wide interproximal spaces, favors the growth of an undisturbed, protected bacterial biofilm. The root caries comprehends an ongoing sequence of clinical manifestation, starting from minuscule areas of slightly softened and discolored dentin up to yellow-­

brownish extended areas, hard or softened, which can sometimes surround the entire root surface (. Fig.  3.5a). The lesions may or may not present a cavity. Besides the mutans group streptococci and the lactobacilli, present in lesions at other regions, the root carious lesion also may be colonized with filamentary bacteria of the genus Actinomyces, which secretions have a proteolytic effect. Patients with periodontal disease often also suffer from root carious lesions.  

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a

b

c

d

..      Fig. 3.19  Carious lesion aspect at the proximal surface. a White spot; b brownish spot; c, d cavity

Initial root carious lesions appear as a radiolucent zone on the root cement. Traumatic brushing, e.g., horizontal brushing of the teeth with great pressure or scraping of the root surfaces, damages and removes the cement exposing the dentin. Therefore, initiation of the carious lesion happens directly in the dentin, which was exposed to the oral environment. In contraposition to the initial lesions at the enamel, the root carious lesions, even at its initial development, can present a softened surface pattern. This results from the microorganism that penetrates through the surface zones of the lesions and because of collagen fibers that are partially exposed by demineralization. Due to the specific microbiota, the dentin destruction spreads much faster than in enamel (. Figs. 3.21a–c and 3.37c, d). The root carious lesions can be classified as active or inactive [73]. The active lesions are defined as an area that demonstrates a yellowish or slightly brownish appearance, with undefined borders. Mostly, this kind of lesion shows a visible bacterial biofilm and presents a softened or leathery consistency when probing with moderate pressure (. Fig.  3.22a). Inactive or arrested lesions present defined borders, with a root surface with dark brown or black discoloration. When probing with moderate pressure, this kind of lesion appears smooth, bright, and hard (. Fig. 3.22b, c).  

 

 

3.7

Caries Diagnosis

For a long-lasting and profound treatment of caries, it is important to detect the respective etiological and determinant factors in the patient and not only to treat lesions that are already cavitated. The diagnosis of caries is not the end point of treatment but a moment to start with prognostic considerations and therapeutic decisions. Many diagnostic methods are used, and they serve the purpose to determine the presence of the disease and its extension in a patient, allowing to choose the most suitable treatment alternative, to monitor the disease progression, to evaluate the efficacy of the treatment, and to determine the presence of factors that may favor the establishment and the progression of the caries. The main objective when obtaining diagnostic information is to improve the patient’s health, and not only to find symptoms and local conditions [50]. The sooner the activity of the disease can be identified, the more favorable will be the prognosis, with greater chances of the re-establishment of the health without damage and sequela. Thus, a precise diagnosis of the activity lesions is indispensable, since this estimation will serve as an indicator for the progression of the disease allowing the adequate treatment.

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..      Fig. 3.20  Carious lesion on the buccal surface. a Opaque active lesions; b, c inactive shiny lesions with cavitation

An ideal diagnostic tool should be trustworthy and capable to detect carious lesion at an initial stage, able to differentiate between reversible and irreversible lesions, and should permit its documentation. If the aim of the diagnosis is the early detection of the carious lesion, the clinician must detect the demineralized areas on the enamel yet in the stage of incipient white spot or at least before the lesions become a cavity. If detected at this stage, lesions might be remineralized or arrested, especially with the help of fluoride applications [90]. In addition, an ideal diagnostic method should have accessible costs, guarantee the comfort of the patient, and be fast and easy to use. It must also to be used in every site of teeth with the same efficacy. In recent times, knowledge of the total number of teeth that presented carious lesions (prevalence), or the number of new cases that happened during a defined period (incidence), were regarded as the main factors to estimate the caries activity of a patient. That approach was only focused on the signs of the disease and not on the etiology [95]. The caries disease does not start at the moment, when clinically visible lesions appear, but much before that time point. Therefore, the activity of the caries and its associated cariogenic factors must be considered to avoid progression of existing or onset of new lesions. For optimal prevention, a broader evaluation of the patient’s conditions is necessary,

including the information about the patient’s diet, salivary factors, and microbiota composition, thereby determining if the patient has a high or a low caries risk [2, 71, 90, 95]. Laboratorial exams to determine the buffering capacity, salivary flux, and the number of Streptococcus mutans and Lactobacillus were improved so that they become simpler, faster, and easier to be conducted in the daily practice. However, the often high costs and the limited gain of precise information have turned those tests frequently inacceptable [44]. Measurement of the stimulated saliva flow, collecting saliva during 5  min, may reveal patients with hyposalivation or xerostomia, which indicates the necessity of taking greater care of the teeth, medical exams, and intensifications of the preventive measures [57]. Additionally, evaluation of the pH and the buffering capacity of the saliva may provide information about the caries risk of a patient [58]. High or very high lactobacilli counts are associated, in many cases, with the high frequency of ingestion of sugar or even a great number of the open carious lesions [57]. The presence of high amount of Streptococcus mutans in the saliva is related to the risk of getting new lesions and could be a useful tool for motivation of the patient [4, 22, 41, 59, 70, 86]. However, general recommendations for using of the bacterial counting tests as a risk assessment tool cannot be justified yet due to lack

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a

b

c

..      Fig. 3.21  a–c Root carious lesion at proximal surface with preservation of enamel and destruction of the adjacent dentin

of well-designed studies [82, 92]. During the clinical examination, high-risk patients very often present multiple primary or secondary carious lesions, multiple endodontic treatments and/or the lost teeth, and restorations on smooth surfaces or on the root, besides a precarious oral hygiene and complete lack of information. In contrast, the typical low-risk patient does not present primary or recurrent lesions, does not have a lack of teeth due to extractions or endodontic treatment caused by caries, and presents no or little restored surfaces and an adequate oral hygiene, with high or good degree of information. Tip

High caries-risk patients very often present multiple primary or secondary carious lesions, multiple endodontic treatments and/or the lost teeth, and restorations on smooth surfaces or on the root, besides a precarious oral hygiene and complete lack of information about prevention.

>> The caries disease does not start at the moment when clinically visible lesions appear, but much before that time point.

3.7.1

 ethods for Detecting and Diagnosing M Dental Carious Lesion

The word diagnostic has a Greek origin (diagnostikós), and it means “knowledge or determination of a disease by mean of signals and symptoms.” Nowadays, diagnosis of the carious aims to decide if a demineralization is present, to investigate the depth of mineral loss and the presence of cavities, besides to the information, whether the process is progressing on a fast or slow speed or if it is arrested [75]. For a minimally invasive dentistry approach and maximum preservation of tooth structure, the earliest detection of the carious lesion is required. When detected in its initial stages, the lesion progression can be stopped [6]. Precise diagnosis of non-­ cavitated lesions is extremely valuable, as an estimation of caries activity, to detect circumstance that needs to be treated with a more intensive preventive program [8]. Many methods can be used to determine the presence or the absence of carious lesions. To analyze how precisely a diagnostic method reflects reality, dichotomous analysis can be performed (presence or absence of the disease), and the results can be compared with another evaluation, called validation standard or “gold” standard. The diagnostic decisions can be positive or negative for the absence of a lesion, and depending on the real state, four types of results can be obtained:

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..      Fig. 3.22  Carious lesion at the cervical region. a Active; b, c inactive

55 True positive decisions – The diagnostic method used was positive for the presence of the lesion, and the validation standard confirmed this result. 55 True negative decisions – The diagnostic method used was negative for the presence of the lesion, and the validation standard confirmed this result. 55 False-positive decisions – The diagnostic method used was positive for the presence of the lesion, and the validation standard did not confirm this result. 55 False-negative decisions – The diagnostic method used was negative for the presence of the lesion, and the validation standard did not confirm this result.

3.7.1.1 

This way, sensitivity of a method, its capacity to diagnose correctly cases in which the lesion really exists (true positive results), and the specificity of a method, its capacity to correctly diagnose the cases where the lesion is absent (true negative), can be defined. Ideally, a diagnostic method must not be invasive and must give reliable and repeatable results, with a high level of sensitivity and specificity. Unfortunately, none of the available methods present a 100% precise result in relation to the existence or not of lesions on all surfaces [75].

3.7.1.2 

Anamnesis

Diagnosis of caries and caries risk starts already with the anamnesis of the patient. The patient needs to be asked about the existence of pain symptom in tooth, spontaneous or provoked. Some patients report pain when consuming cold or sweet food or drinks, or when they touch the tooth. The temperature variation produced by the cold and variation of the osmotic concentration by the sugar provoke a dentin fluid movement, which leads to hypersensitivity and pain. Presence of pain to a simple touch of a tooth may be signs of pulpal inflammatory process, which must be further investigated.

Visual Examination

The visual examination is the simplest way to check for abnormalities or diseases of dental structures. It is self-­ evident that a removal of the entire bacterial biofilm and/or extrinsic stains should precede the examination. Cotton rolls must be placed and the surface must be completely dried with a blow of air. A good illumination of the operating field is also fundamental. The teeth must be analyzed with a clinical mirror of good quality, preferably to the ones with a reflexive area on the surface of the mirror, also called first

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..      Fig. 3.23  Teeth with darkened grooves showing the absence of lesions on the transversal section

surface mirror (. Fig. 4.41a–c). All tooth surfaces should be inspected. Plaque disclosing agents may help to determine the presence and quantity of bacterial biofilm. The eruption stage of teeth should also be evaluated, and presence of gingiva partially covering the occlusal surface of an erupting tooth should be noted, since it can increase the retention of a biofilm. After the tooth cleaning, cotton roll isolation, and drying, the existence of dark groove and groove with white spot lesions at the entrance has to be verified. In . Fig.  3.23, a human tooth extracted with occlusal dark-colored grooves is shown. After it was sectioned in two parts, none of them present a carious lesion, showing that the dark discoloration was only due to staining. In . Fig.  3.24, the darkened areas were associated with white spot lesions that were arrested and then stained. Even though there was a demineralization of the dentin, a cavity was not created, and the lesion was arrested. In . Figs. 3.25 and 3.26, teeth with some grooves only stained and other with cavities are shown. This corroborates the before-mentioned fact that darkening of grooves is not a good indicator for the presence of a carious lesion. A darkened groove can simply be a biological sealing or an inactive white spot lesion, which was stained by dyeing substances in the diet. However, it can also be related with cavities and hidden carious lesions on dentin, which aggravates the diagnosis. Carious lesions are cavitated when the collapse of the undermined enamel has happened. In those cases, diagnosis is simple, and the coloration of the dentin should be analyzed, which may give a hint to the caries activity. A dentin lesion with light brown color and wet appearance indicates an active lesion (acute), while a darkened and dry dentin may serve as an indicator for an inactive lesion or little activity (chronic) (. Fig. 3.27a, b). Diagnose is much more impaired for un-cavitated lesions with an apparently intact enamel surface. An indicator for the presence of a lesion in dentin is the presence of opacity through the enamel adjacent to a darkened groove (. Fig. 3.28). Another indicator for the presence of dentin lesions are microcavities that may be associated with white

..      Fig. 3.24  Teeth with discolored groove showing the presence of arrested and pigmented carious lesions in enamel, without cavitation

 

 

 

 

..      Figs. 3.25 and 3.26  Teeth with discolored groove showing the absence of lesions, on the transversal section in certain region of the central groove, and cavitated lesion at other sites

 

 

spots (. Fig. 3.29a, b). However, some studies showed that when microcavities are clinically detectable in grooves, in fact, only 31–42.7% of real lesions exist in the underlying dentin. In contrast, when the microcavities were associated to the presence of adjacent white spots, dentin lesions were existent in 78–91.2% of the cases. This means that the  

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b

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..      Fig. 3.27  Open occlusal carious lesions. a Acute carious lesion; b chronic carious lesion

However, it was demonstrated that 30–60% of the pits and grooves, where the instrument gets stuck, did not present carious lesions. The instrument may get retained only because of the occlusal anatomy, leading to a wrong diagnosis, as shown in . Fig. 3.32a–d. The probing can also cause destruction of the surface zone of a white spot lesion, thereby creating a cavity with bacterial invasion into the lesion body [21, 24]. In addition, when probing all grooves, cariogenic bacteria can be transferred from one place to another, contamination sites which were previously free from this kind of bacteria [21]. Some studies also demonstrate that the use of probing is not more precise than the visual examination by itself, to detect occlusal incipient lesions, showing low sensitivity [61]. Therefore, the exploratory probe should only be used at open lesions to check the consistency of the dentin tissue. Probing of intact surfaces of root caries lesions with a sharp probe may create also small cavities, thus reducing the chance of remineralization. Therefore, a periodontal probe with a blunt tip must be used, such as a WHO ball-ended probe, making possible to feel the consistency of the tissue, without damaging the surface. On the proximal surfaces, the tactile exam can be performed with a dental floss. In case the dental floss comes to rip when passing this region, a cavity with sharp edges might be present in the region.  

..      Fig. 3.28  Presence of opacity under enamel

association of white spots and microcavities is a strong indicator of the need of intervention on an occlusal lesion [75]. The visual exam of the occlusal surface by itself has a sensitivity of 62% and a specificity of 84% [61]. On the proximal surfaces, the visual exam can be effective in the cases where the lesion has already considerably developed toward the marginal ridge. An alteration in color right below the ridge can be observed. In more advanced lesions, even a rupture of the ridge might appear (. Figs. 3.30a, b and 3.31a, b). All teeth must be also observed from the buccal and lingual aspects, searching for any changes in color and translucency. At root carious lesion on the buccal or lingual surfaces, the visual exam must determine whether the lesion is active or inactive. However, the main difficulty is found at proximal surfaces, where there is no access to direct vision, and complementary examinations are necessary.  

3.7.1.3 

Tactile Examination

In the past, it was recommended for diagnosing occlusal lesions that a very sharp exploratory probe was moved through the bottom of the grooves. Retention of the probe should indicate carious lesions needed to be treated.

3.7.1.4 

Radiographic Examination

The radiographic examination is the most important auxiliary tool to diagnose carious lesion, showing whether a certain loss of dental mineral is present or not. It presents the advantages of being not invasive, allows the detection of hidden lesions, and is helpful to follow progression or regression of lesions. However, it is not capable to detect lesions at early stages, because the little mineral loss at this stage is not high enough to be visible on a radiographic image [77]. In addition, it does not directly distinguish between presence and absence of cavitation. However, the depth of the lesion as depicted on a radiograph mostly correlates with the status of the surface. That means, the deeper a lesion is on an X-ray, the more probable a cavitation is present. Due to the overlap-

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a

b

..      Fig. 3.29  a Presence of the micro-cavitation and opaque areas below the enamel (arrow); b carious tissue removed by cavity preparation

a

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..      Fig. 3.30  Clinical signs of a carious lesion at the proximal surfaces. a Darkened aspects under the marginal ridge; b breakage of the marginal ridge

a

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..      Fig. 3.31  Clinical signs of a carious lesion at the proximal surfaces of anterior teeth. a Darkened aspect under the marginal ridge; b open cavity

ping of images, there is a risk of a false-positive result, generating images of ambiguous interpretation. With respect to occlusal surface lesions, the radiographic examination is able to detect 33% of incipient carious lesions in dentin and 100% of deep caries lesions. The occlusal

changes are observed on a radiography, when the demineralization has histologically reached the medium third of the dentin (2–3 mm beyond the DEJ). At this stage an invasive treatment might be required [85]. In general, the time from the onset of an occlusal lesion until reaching a radiographic

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b

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..      Fig. 3.32  Retention of the exploratory probe in the groove due to the occlusal anatomy. a Occlusal view; b retention of the probe; c, d transversal cut of the area, where the probe got stuck, showing the absence of lesion

evidence in dentin can take from 3 to 9  years [66]. In . Fig. 3.33a–d, radiographic images of lesions of the occlusal surfaces are shown. Monitoring of existing lesions can be conducted as an alternative to invasive treatments. In patients with high caries risk, radiographic examination might be advisable to be performed every 1–2  years, whereas in patients with low risk, it can be performed every 2–4 years. Indication to an invasive treatment has a direct relation with the presence of a cavitation, which is not accessible to regular removal of biofilm with oral hygiene measures. A cavitation often makes it impossible, at least at proximal regions, to remove the bacterial biofilm, thus rendering control of the lesion impossible. In those cases, a restoration will turn the previously cavitated surface into a smooth surface, which could be adequately kept clean. Following these considerations, only cavitated and not accessible lesions must be restored. White spot lesion should be treated with preventive measures. However, at the proximal surfaces being in contact with adjacent teeth, the surface of a lesion could not be directly checked. Thus, decision taking must be based on indirect methods as radiographic examination. To get confirmation if a proximal lesion is cavitated or not, it might be helpful to perform a tooth separation, using orthodontic rubbers for 1–2 days. After this the teeth may be separated enough to allow direct vision to the proximal surfaces. In  

studies, injection of a silicone impression material into the proximal space is often done. After curing and removal, the presence or absence of cavitation could be verified in the impression (. Fig. 3.48a–i). Based on the radiographic image, the caries lesion on the proximal surface can be classified according to its depth in one of six scores. For that, enamel is divided into two halves, while the dentin is divided in three thirds (. Fig. 3.34). When nothing is seen, the score E0 is applied. When the lesion is located on outer half of the enamel, it is classified as E1, while when reaching the inner half of the enamel, it is scored E2. The lesions located on the outer third of dentin are D1, while reaching the middle third of dentin, they scored as D2. Finally, when located on the inner third of dentin, they scored as D3 [9]. Studies tried to correlate the depth of the lesion, according to the radiographic image, and the presence of cavitation. They observed that E1 lesions had almost no cavitation, while E2 was cavitated in only 10–19.3% of the cases [3, 80]. However, 32% of D1 lesions were cavitated, while 72% of lesions extending into the inner 2/3 of the dentin (D2 and D3) also showed cavitation [43]. In addition, some studies observed that when the radiolucency reaches the inner third of dentin (D3), cavitation was present in 100% of the cases [3, 67, 80]. Taking this into consideration, the depth of a carious lesion on a radiographic image allows to  

 

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a

b

c

d

..      Fig. 3.33  Radiographic images suggestive of carious lesions at the occlusal surfaces (arrows)

It has to be noticed that lesions visible on a radiography have more deeply progressed histologically. . Figure  3.36 presents a relation between the histological, radiographic, and clinical aspects of a carious lesion at proximal surfaces. In summary, when the carious lesion in enamel has histologically reached at least half of the thickness of the enamel, it is not visible clinically nor radiographically. Only when it has reached more than half of the thickness of the enamel histologically, it will appear as a radiolucent area in the outer half of the enamel and clinically as a white spot. Only the lesion that is radiographically already in dentin shows association to clinical or histological presence of a cavitation. The radiographic examination is also valuable, in cases, in which a lesion is hidden inside a periodontal pocket. Those lesions present a very fast progression, and the patients should be monitored radiographically more often than patients with a low caries risk. In . Fig. 3.37a–d, X-rays with radiolucent areas suggesting carious lesions at root surfaces are depicted. Nowadays, besides the radiographic films, sensors are available that transfer the information of the image directly to a personal computer. The advantage of digital radiographies is the possibility to process the image by a software, adjusting the contrast and brightness, allowing a better observation of the details, and performing more precise diagnosis [90]. There is also a possibility of using a computer-­  

E1 E2

D1 D2 D3

..      Fig. 3.34  Classification of caries lesions according its depth. The enamel is divided into two halves (E1 and E2), while the dentin is divided in three thirds (D1, D2, D3)

estimate the cavitation risk, selecting between an invasive or noninvasive intervention. Therefore, invasive restorative treatments are not recommended until radiolucency has reached dentin. In . Fig. 3.35a–e, examples of X-rays of various situations are given. It should however be noted that the radiographic examination of the proximal surfaces has high specificity (95%) but only a moderate sensitivity (59%) [40].  

 

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b

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..      Fig. 3.35  Radiolucent images of proximal surfaces of posterior teeth. a Lesion on the outer half of the enamel, E1; b inner half of the enamel, E2; c outer third of the dentin, D1; d middle third of the dentin, D2; e inner third of dentin, D3

aided detection tool, which is a software analyzing tooth density and demineralization patterns for interproximal caries (Logicon Caries Detector, Carestream Dental, Atlanta, GA, USA). It extracts characteristics of the images from the digital radiography and correlates it with a database of known lesions, allowing to obtain more information from digital radiography than with the naked eye. This software analyzes

shades of gray and is capable to localize and classify proximal carious lesions, indicating the depth of the lesions [35]. The image shows superimposing lines representing the borders of the lesion over the image from the digital radiography, besides graphics indicating changes of mineral density and the probability of the presence of a carious lesion [32, 93]. A study showed a sensitivity of 90.5% and specificity of 88.3%

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on the occlusal surface. However, this could lead to ­ambiguous results, due to the specific morphology of this region. Nevertheless, FOTI can be an auxiliary to the visual exam to detect extensive hidden lesion in dentin [65, 75, 94]. Transillumination can also be used at anterior teeth to verify NAKED EYE the presence and the extension of composite restorations and recurrent caries at the gingival margins. The transillumination method presents the advantage of not being invasive, being simple and comfortable for the patients, and not requiring radiation, being very valuable when a radiography is not possible to be performed. An innovation of FOTI method was the introduction of computer-assisted image analysis of the transilluminated PROBE WHITE SPOT area, called digital imaging fiber-optic transillumination NAKED EYE CAVITY (DIFOTI, Electro-Optical Science, Irvington, NY, USA). For that, the light from a probe is placed on one side of a tooth, ..      Fig. 3.36  Schematic drawing of the histological stages of a carious and the image in the non-illuminated opposite side is caplesion correlating with the radiographic and clinical examination. tured by a camera and then analyzed by a software. This Histological aspect of the lesion is always bigger than the clinical and method has the potential to detect initial lesion and to evaluradiographic. (Adapted from Darling [18]) ate its progression, besides the possibility of image documentation [97]. Under in vitro conditions, the diagnostic accuracy when the software was used [35]. The author highlighted that of DIFOTI in detecting early approximal enamel lesions is the software use promoted 20.2% of improvement on the greater than that of film and digital radiography, while the sensitivity, in relation to when it was not employed [35]. potential for detecting lesions in dentin is similar for all three methods [10]. 3.7.1.5  Fiber-Optic Transillumination While the FOTI and DIFOTI use visible light, the posThe principle of the fiber-optic transillumination (FOTI) is sibility of using near-infrared light was also investigated based on the fact that the teeth present different light trans- [34]. It was observed that longer wavelengths showed lower mission indexes that may vary accordingly to its state of light scattering inside the tooth structure, being able to healthiness, the presence or not of carious lesions, calculus, penetrate more deeply and produce a higher contrast and restorative materials. Taking into account that a carious between the caries and the sound hard tissue [38, 51]. Thus, lesion presents a lower light transmission index than the the near-infrared light transillumination (NILT) method intact structure, an area affected by caries will be seen, when was created, and a new camera was developed, named transilluminated, as a dark shadow that follows the external DIAGNOcam (KaVo, Biberach, Germany). The camera has contour of the lesion [75]. With this examination tool, dental two light sources, using a wavelength of 780 nm, which are calculus appears as a dark area involving the cervical third of placed buccally and lingually to the tooth to be examined, the tooth. For adequate use of FOTI, teeth should be clean illuminating the crown from cervical to occlusal and not and the light of the dental unit must be turned off. A light-­ directly into the interproximal space. A digital video camemitting device with an optical fiber probe tip is used, with era is located above the occlusal surface and shows the interchangeable tips of various diameters, or even a low-level scene live on the screen, in monochromatic grayscale, being laser device emitting visible red light. possible to capture different stages of interproximal enamel For the detection of the proximal lesion in anterior teeth, and dentin lesions and cracks, which are clearly visibly as the probe tip must be applied on the lingual aspect, and the darker shadows (. Fig. 3.39). Studies showed a sensitivity of alteration of the light transmission is observed on the labial 72.73–99.2% for lesion on DEJ [56, 98] DIAGNOcam is side, or vice versa (. Fig. 3.38a, b). On the proximal areas of more capable of detecting initial proximal lesions than posterior teeth, a small probe tip with 0.5  cm in diameter digital radiography and also has a higher sensitivity for must be used to get information of the proximal tooth sur- dentin lesions [60]. face (. Fig. 3.38c, d). The tooth must be dry and the probe tip be positioned below the proximal contact point, touching the 3.7.1.6  Electrical Conductance Measurements gingiva from buccal or lingual sides. The changes in light This method is based on the principle that the electrical contransmission can be observed from the occlusal aspect, on ductance of the enamel is directly related to the degree of the the marginal ridge. If a lesion is present, a darkened shadow porosity of the tissue. In principle, intact enamel is a good will appear. This method diagnoses most of the proximal electrical insulator. During development of a carious lesion, carious lesions in dentin. For the occlusal surface lesions, a mineral loss results in an increase of the porosities that, in probe tip of 2 mm in diameter must be positioned next to the general, are filled with water and saliva ions. With the margin of the gingiva on the buccal or lingual surface. The increase of the size of the pores, a network of interconnected changes on the light transmission will be visible as shadows water-filled paths allows the passage of electrical current, HISTOPAHOLOGY

 

 

 

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a

b

c

d

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..      Fig. 3.37  Radiographic images associated with carious lesion on the root surfaces

reducing the insulating characteristic of the dental enamel. Therefore, the greater the demineralization degree of the enamel, the greater the electrical conductivity is [45]. The device indicates the dental structural integrity through visual and sound signals. It presents an electrode that is placed on the dental surface and a handpiece, which is given to the patient to hold, closing the electrical circuit of low intensity

(3 μA) (. Fig. 3.40a, b). A study showed a sensitivity of 61% and specificity of 86% for the diagnosis of enamel lesions on the occlusal surfaces and sensitivity and specificity values both of 76% for lesions in dentin [83]. Examples available on the market are the Electronic Caries Monitor III (ECM III; LODE, Groningen, The Netherlands) and the CarieScan (CarieScan Limited, Dundee, Scotland).  

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a

b

c

d

..      Fig. 3.38  Transillumination of a carious lesion. a, b Interproximal area of anterior teeth; c, d interproximal area of posterior teeth

incident light and emit a light with another color, called fluorescence. For the principle of QLF (quantitative light-induced fluorescence), it is important to notice that tooth fluorescence is caused by the presence of the chromophores inside enamel and dentin. When a sound tooth is irradiated with blue light, the chromophores inside the dentin are excited, shining with green dentin back-illumination. Due to the carious process, the enamel is getting more porous, leading to scattering of the dentin back-illumination in the enamel. Thus, the illumination is reduced in the area of the white spot lesion, providing a “dark” reflection of the tooth at this site. The reflected light is captured by a camera and analyzed by software that quantifies the mineral loss (Inspektor Dental Care, Amsterdam, The Netherlands). . Figure 3.41a, b shows an extraoral camera for obtaining images of whole arcs of teeth (e.g., frontal, sides, occlusal, and lingual) and an intraoral QLF camera for zooming in on specific element surfaces. The dental fluorescence information can be stored in a computer and used for monitoring of initial lesions [5]. As mentioned, the incipient lesions appear as dark spots, while more extended lesions (. Fig. 3.41d) and the biofilm (. Fig.  3.41f) appear in red, indicating the presence of bacteria. This can easily be shown to the patient, increasing the motivation for preventive daily practices [90]. The DIAGNOdent device (KaVo, Germany) works with a different principle. It irradiates the tooth with red light at  

..      Fig. 3.39  Transillumination of caries lesion on the proximal surface (arrow) using DIAGNOcam (KaVo). (Image kindly provided by Dr. Pune Nina Paqué (Zurich University – Switzerland))

3.7.1.7 

Fluorescence Measurements

This method is based on the principle of fluorescence of chromophores naturally incorporated in the mineralized dental hard tissues or originating from bacteria. When those chromophores, e.g., porphyrin or porphyrin derivatives, are stimulated by light with specific wavelengths, they absorb

 

 

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655 nm coming from a diode laser. When the probe is directed to a tooth surface, it induces fluorescence from chromophores, which can be captured and measured. The results are presented on an electronic screen with values from 0 to 99. The lower the mineral content of the structure, the more chromophores are incorporated and the greater the fluorescence is. A a

direct correlation exists between the measured value and the size of the lesion (. Fig.  3.42a) [28, 75]. It however shows some problems in the detection of lesions when organic, fluorescent residues in the grooves and pits are present, giving a false-positive result. Therefore, prophylaxis with a sodium bicarbonate abrasive blast or bristle brush with pumice should  

b

..      Fig. 3.40  Device for caries detection using electrical conductance measurement (CarieScan)

a

b

c

d

..      Fig. 3.41  Quantitative light-induced fluorescence. a Extraoral QLF camera for obtaining images of whole arcs of teeth (Qraycam, Inspektor Research Systems); b intraoral QLF camera (Qraypen, Inspektor Research Systems); c image under natural light showing

proximal lesions (arrows); d under blue light, the red fluorescence of the caries lesion (arrows) helps the diagnosis; e image of the lower arch under natural light (the biofilm is not visible); f red fluorescence of the biofilm in molars and tongue under the blue light

107 Cariology

e

f

..      Fig. 3.41 (continued)

a

b

..      Fig. 3.42  Device to quantification of the induced fluorescence by laser. a DIAGNOdent; b The Canary System

be performed before the reading, to remove the residues of organic material. For the use of this device, the surface to be evaluated needs to be cleaned and dried. It has a sensitivity to detect lesions in enamel on the occlusal surface of 79% and a specificity of 74% [62]. It is not adequate for diagnosis of recurrent caries next to restorative materials, and it is not capable to differentiate active from inactive lesions [90]. The Canary System (Quantum Dental Technologies, Toronto, Canada) uses a low-power pulsed laser light, which is converted to heat to detect caries lesions (. Fig.  3.42b). Usually, caries modifies the thermal properties and luminescence of teeth. As a lesion grows, a corresponding change of those parameters appear. When the light from The Canary System is absorbed, these two phenomena are observed, namely, the occurrence of fluorescence (luminescence) and the release of heat (photothermal effect). The reflected heat from a demineralized caries lesion site is increased, and the fluorescence signal of a caries-affected tooth is decreased [1, 49]. The temperature rise is only 1–2 °C, and it does not cause harm on the tooth. A study showed a sensitivity of 93.3% and specificity of 82.5 for proximal lesions [56]. However, at the  

moment there is a lack of independent studies for giving a final judgment of the system. A new generation of intraoral cameras came to the market with multiple functions. They can be used as regular intraoral cameras, with illumination provided by white LEDs, or as special diagnostic tools when the illumination is provided by colored LEDs, capable to induce tooth fluorescence. They also offer some software to analyze the collected images and help the clinician with the treatment decision. One example is Soprolife (Acteon, La Ciotat, France), an intraoral camera that has blue LEDs capable to induce the autofluorescence, helping to identify caries-affected areas. The software can work on the image, and the caries lesions are detected as red color, while the surrounding tissue is displayed in black and white. Another example is VistaCam iX (Durr Dental, Bietigheim-Bissingen, Germany), which has interchangeable heads intended for specific uses [60]. The “Proof ” head emits violet light (405  nm) that stimulates bacterial metabolites, causing them to glow red. The healthy enamel can be identified by green fluorescence. A software shows caries via a color scale and numerical values (. Fig. 3.43).  

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b

c

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..      Fig. 3.43  Intraoral camera inducing the tooth’s autofluorescence. a View of the occlusal surface of a caries-affected tooth under natural light; b scheme showing the occlusal surface being illuminated by violet light, causing red fluorescence of the caries lesion. (Picture kindly

3.7.1.8 

Reflection and Refraction Measurement

The technology for measurement of the reflection and the refraction of the tooth using LED light source (Midwest Caries I.D., Dentsply Professional, York, PA, USA) has been developed to detect caries lesions. The functioning of the device is based on the fact that the whole enamel, due to the layering of adjacent prisms, presents a translucent crystalline nature, which allows light to pass through it. When there is a demineralization, the crystalline structure is degraded, narrowing the prisms and leaving spaces between them. As a result of that, carious enamel is less translucent than sound enamel. To detect a carious lesion, the device emits a light that comes from an LED and penetrates through the enamel. It uses three separated optic fibers inside the probe, the first emits green light, the second emits red light, and the third is a receptor fiber, to collect the light reflected by the tooth. If the enamel is sound, the light is absorbed by the tooth and the green light remains turned on. If a demineralization is present, the light will be reflected, refracted, or spread. The receptor fiber will capture this light, and the green light will be turned off, while the red one will be turned on. At the

provided by Dürr Dental SE, Germany); c image obtained by VistaCam (Dürr Dental) showing red glowing on the caries-affected area. d Image analyzed by software, converting the fluorescent emission to different colors according to the caries lesion depth

same time, a sound signal will be emitted, alerting the user that the structure has changed (. Fig. 3.44). This method has shown its capability to diagnose 92% of the occlusal lesions and 80% of the proximal lesions [90]. For the detection of the proximal lesions, the probe needs to be directed parallel to the long axis of the tooth over the marginal ridge. The same VistaCam iX (Durr Dental), previously discussed for fluorescence evaluation, has also a “Proxi” interchangeable head intended for detection of proximal caries by reflection of infrared light (λ = 850 nm) (. Fig. 3.45a). That wavelength makes healthy enamel appear translucent, while caries lesions, by reflecting more waves, create a light opaque appearance on the image (. Fig. 3.45b) [47].  

 

 

3.7.1.9 

Image Magnification Method

It seems obvious that magnification of the image sizes of the tooth structure helps to improve diagnosis and detection of irregularities. Studies comparing caries detection and diagnosis performed by dentists with naked eyes, with the results obtained using magnifications aids, showed better results for the groups using the support of magnifications [31, 90]. The videoscope method uses an intraoral camera to aid the diag-

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Red indicator fiber

Green indicator fiber

Receptor fiber

..      Fig. 3.44  Midwest Caries ID (Dentsply)

nostic process (. Fig. 3.46a, b). Its advantage is that it generates an image 5–10 times bigger than the naked eye, and that is part of a computer system, which allows adjustment of brightness and contrast of the image. Similar to the visual exam with naked eyes, the tooth surface must be clean and dry. Some studies demonstrated that this method increases the sensitivity but it reduces the specificity. Other possibilities to get magnified images are the use of operative microscopes, or magnifying lenses and loupes (7 Fig. 4.57a, b).  

 

3.7.1.10 

Temporary Elective Tooth Separation

Due to the difficulty of diagnosing carious lesions at proximal surfaces, the technique of the temporary elective tooth separation can be a help, allowing direct visible access to the proximal surface. It can be performed by the immediate or delayed technique. The immediate technique uses mechanical separators or wooden wedges to separate the teeth (. Fig. 3.47a–c). Initially a topical anesthesia is applied on the interdental gin 

gival papilla, and the separator is placed and slowly closed. However, there is some discomfort, and if it is not done carefully, it can cause damage to the periodontal tissues. The slow or delayed technique consists in using orthodontic rubber band separators (. Fig.  3.48). They can be positioned by two dental tweezers or two pieces of dental floss (. Fig. 3.49a–i). When it is placed, the rubber ring must surround the proximal contact. It should stay in position for 24 h (incisors), 3 days (premolars), and up to 1 week (molars). The space gained varies from 0.35 to 1 mm. After this period, there is a direct vision to the proximal surface allowing for diagnosis of caries lesions or cavities (. Figs. 3.49f and 3.50b). Also, a light silicone impression material can be injected into the interproximal space, using an impression syringe with a thin tip [87] (. Fig. 3.49g). The impression can be used for checking presence of cavitation at this proximal area (. Fig.  3.49i). After the rubber ring is removed, space will close itself in about 48 h.  

 

 

 

 

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Besides the abovementioned supplementary tools for detecting and diagnosing caries, there are others on the market or in developmental state, which are not described in this

3

a

chapter. Generally, it should be noticed that there is no instrument or device, which alone provides enough information for a correct detection and diagnosis of caries. They should be seen as supplementary devices to support the visual and radiographic evaluation. 3.7.2

b

..      Fig. 3.45  Detection of caries lesion by reflection of infrared light. a Scheme of light emission and reflection by the Proxi head of VistaCam iX (Dürr Dental). b Image of the proximal surface. The healthy enamel appears translucent, while the caries lesions, by reflecting more waves, show a light opaque appearance (arrows). (Images kindly provided by Dürr Dental SE, Germany)

a

..      Fig. 3.46  a Intraoral camera; b camera in position to obtain an image

Secondary Carious Lesions

Patients may present carious lesion at the margins of existing restorations, generally called secondary carious lesions. It is nowadays considered just another primary carious lesion, located near to an existing restoration. They can be a result of mistakes during the restorative procedures, as the incorrect use of the matrix and wedge system or the incorrect placement of the restorative material into the cavity, resulting in defective spaces at the interface, or the incorrect use of the adhesive system and light-curing, leading to the formation of marginal gaps. One important reason for the appearance of new secondary lesions is the fact that only the carious lesion was treated, and not the disease of the patient, thus leaving the caries risk on high level. Therefore, new lesions will happen, and many of them will begin on the interface between tooth and restorations, because it is a propitious region for biofilm retention. Clinical studies observed that in adults, secondary carious lesions are eight times more frequent than the primary ones, especially on those who are more than 50  years old [11, 37]. Thus, secondary carious is the greatest reason for the failure of restorations. The difficulties on the diagnostics of the secondary lesions are, in some aspects, similar to the one of the primary lesion. As with primary lesions, there is a difficulty in differentiating whether the lesion is active or inactive. There is no current method providing an insight into the activity of secondary lesions. Wall lesions are secondary carious lesions, which occur at the interface between the restorative material and the cavity wall. The color next to the amalgam restoration represents a problem for proper diagnosis, since the gray or bluish appearance can either be because of amalgam corrob

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a

b

c

..      Fig. 3.47  Immediate dental separation. a Ivory (for anterior teeth) and Eliot (for posterior teeth) separators; b Ivory separator in position; c Eliot separator in position

..      Fig. 3.48  Orthodontic rubber band separators with different diameters

sion or due to secondary lesions [11]. On the other hand, with composite restorations, the interfacial staining and the presence of darkened areas under the enamel, next to the margins, can be an indicator that marginal microleakage is going on, and it can be associated to the presence of secondary lesions (. Fig.  3.51a–f). However, marginal staining of composite restorations should not be considered as the key  

indicator for existence of secondary caries. With time, all adhesive interface soaks some water and saliva, accompanied by discoloring agents. Thus, marginal staining must not be mixed up with secondary caries. Lesions at proximal surfaces represent 94% of secondary lesions at amalgam restorations and 62% at composite restorations [69]. Due to superimpositions on a radiograph, they cannot in all cases be detected on X-rays [29]. Therefore, the radiography must be used in conjunction with a meticulous clinical examination, including probing of the margins, to determine if the lesion has or has not a cavity [11]. During probing, it must be verified if there is lack or excess of restorative material on the margins, as well the presence of the marginal ditches. For that, the probe must be moved from the surface of the restoration toward the tooth structure, and vice versa, crossing the interface. If the probe gets stuck on both ways, there is a ditch on the interface. If it gets stuck only toward the restoration, there is an excess of restorative material, and it should be removed. If it gets stuck only toward the tooth, there is a lack of material. On those cases of lack of material and ditch, a restorative intervention will only be necessary if there is an exposure of dentin. In . Fig. 3.51a–f, clinical images of secondary carious lesions are shown, while in . Fig.  3.52a–d radiographic images are presented.  

 

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a

b

c

d

e

f

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..      Fig. 3.49  Delayed dental separation technique followed by impression. a Radiography showing radiolucent image on the mesial surface; b darkened aspect under the marginal ridge; c–e placing the

3.8

Treatment Decision

For treatment decision after caries diagnoses, many factors must be considered. Firstly the caries risk of the patient must be taken into consideration and should be addressed. In case of lesions imposing risk to pulpal vitality, a possible approach might be to close cavities temporarily, e.g., with glass ionomer cement, thus achieving an oral environment stabilization (OES). This reduces the oral bacterial load and allows for interventions to reduce the carious risk before final treatment. The goal is to achieve an oral environment,

rubber ring with dental floss straps; f separation was reached; g, h silicone injection into the space; i mold showing the presence of cavitation (arrow)

in which demineralized areas may remineralize and in which no new lesions will appear in the future. In case of unclear situations, which do not definitively indicate an active cavitated carious lesion, which is inaccessible to hygiene measures, or in patients with low caries risk, a more restrictive and defensive attitude should be applied. Under those circumstances the indication to perform restorative procedures should be postponed and reevaluated after monitoring. It should be considered that progression of initial carious lesion may take some years before approaching inner dentin areas [68].

113 Cariology

g

h

i

..      Fig. 3.49 (continued)

a

b

..      Fig. 3.50  a, b Tooth separation that allowed enough space to have a direct view to the cavity, without the need of impression

Tip

55 Consider the caries risk and activity before treatment decision. 55 Use different methods for caries diagnosis to prove presence or absence of cavitated caries lesions. 55 Establish individual regimes to maintain intraoral conditions favoring oral health.

>> Individuals present individual caries risk, which should be considered and addressed by dentists.

3.9

ICDAS

The International Caries Detection and Assessment System (ICDAS) is a scoring system for clinical detection and assessment of dental caries lesion. Its aim is to obtain quality infor-

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a

b

c

d

e

f

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..      Fig. 3.51  Secondary carious lesions. a, b Lesion at the interface with the buccal cavosurface margin being probed; c, d observation of a secondary lesion on the buccal wall, seen through transparency on the

buccal enamel and more evident on the occlusal view; e caries lesion (red arrow) detected after removal of the restoration on the distal surface of the canine; f staining of the tooth-restoration interface

mation for an appropriate diagnosis, prognosis of caries, and clinical management. Based on the measurement of surface characteristic of the lesion, mainly by visual analysis, the potential histological depth and activity of the lesion is considered, helping the decision-making process about the most recommended treatment. The system has two criteria, which are the detection and the activity of the lesions. The original ICDAS was created in 2003, but several improvements were performed, and the second version became available in 2005, named ICDAS II [20, 81, 88, 99].

The system has two categories, which are coronal primary caries and root caries. For the coronal caries, the lesion is identified by two digits: the first is related to the level of previous dental treatments performed on the tooth and receives codes ranging from 0 to 9 (. Table 3.1), and the second digit is used to identify the lesion extension and receives codes ranging from 0 to 6 (. Table 3.2) [20, 81]. However, the detailed description of the lesion extension is done separately, based on the place where the lesion is located and the presence of previous restorations, since the  

 

115 Cariology

a

b

c

d

..      Fig. 3.52  a–d Radiographic images of a secondary carious lesions at the gingival walls

visual signs associated with each code can vary, resulting in four headings: 55 Pits and fissures 55 Smooth surface with contact – mesial or distal surfaces that have contact with adjacent teeth and require visual inspection from the occlusal, buccal, and lingual directions

55 Free smooth surfaces – buccal and lingual surfaces and mesial and distal surfaces that have no adjacent teeth and allow direct examination of buccal, lingual, mesial, and distal surfaces 55 CARS – caries associated with restorations and sealants

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..      Table 3.1  First digit of the ICDAS II coding system, related to the previous dental intervention [20, 88, 99]

..      Table 3.3  Description of the ICDAS II codes for pit and fissures [20, 88, 99]

Code

Previous intervention

Code

Description

0

Surface not restored or sealed

0

1

Partial sealant

There should be no change in enamel translucency after 5 seconds of air-drying

2

Full sealant

1

3

Tooth colored restoration

4

Amalgam restoration

5

Stainless steel crown

When seen wet there is no evidence of any change in color. After 5 seconds of air-drying, a carious opacity or discoloration is visible that is not consistent with the clinical appearance of sound enamel and is limited to the confines of the pit and fissure area

6

Porcelain or gold or PFM crown or veneer

2

7

Lost or broken restoration

When wet there is a carious opacity and/or brown carious discoloration which is wider than fissure (the lesion is still visible when dry)

8

Temporary restoration

3

96

Tooth surface cannot be examined

97

Tooth missing because of caries

98

Tooth missing for reasons other than caries

99

Unerupted

When wet there is a carious opacity and/or brown carious discoloration which is wider than fissure. Once dried for approximately 5 seconds, there is carious loss of tooth structure at the entrance to, or within, the pit or fissure/fossa, but dentin is not visible in the walls or base of the discontinuity

4

This lesion appears as a shadow of discolored dentin visible through an apparently intact enamel surface, which may or may not show signs of localized breakdown. The darkened area may appear as gray, blue, or brown in color and is seen more easily when the tooth is wet

5

Cavitation in opaque or discolored enamel exposing the dentin beneath

6

The cavity is deep and wide and dentin is clearly visible

..      Table 3.2  Second digit of the ICDAS II coding system, related to the lesion extension [20, 88, 99] Code

Lesion extension

0

Sound surface

1

First visual change in enamel

2

Distinct visual change in enamel

3

Localized enamel breakdown (without clinical visual signs of dentinal involvement)

4

Underlying dark shadow from dentin

5

Distinct cavity with visible dentin

6

Extensive distinct cavity with visible dentin

. Tables 3.3, 3.4, 3.5, and 3.6 describes the application of the  

codes for each situation of coronal primary caries. For the second categories of ICDAS II, related to the root caries, the system is divided into two groups, depending if the surface has or no restoration. Despite that, the codes are basically the same (. Table 3.7) [20, 81, 88]. The ICDAS II system also assesses the caries activity to determine the caries risk status and the prognosis of the treatment. That allows to identify patients who may require  

intensive preventive intervention. . Table  3.8 shows the activity criteria for coronal caries. For root caries, the color, perception on probing, appearance, texture, cavitation, and location can help the determination of the lesion activity, as described on . Table 3.9 [20, 81]. In addition to the detection and assessment system, the International Caries Classification and Management System (ICCMS) was proposed for handling the patients with regard to caries prevention, aiming to promote health and preservation of tooth structure. Besides the assessment of the caries process, it proposes a risk-adjusted preventive care, control of non-cavitated lesions, and conservative restoration of the cavitated ones. The key elements of ICCMS are classification of the lesions according to their severity and activity, management of preventive care plan and risk status, and risk-­ based recall interval including monitoring and review, creating an optimal personalized caries management plan for optimal long-term health outcomes [81].  

 

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..      Table 3.4  Description of the ICDAS II codes for smooth surface with contact [20, 88, 99] Code

Description

0

There should be no change in enamel translucency after 5 seconds of air-drying

1

When seen wet there is no evidence of any change in color. After air-drying a carious opacity is visible that is not consistent with the clinical appearance of sound enamel and is seen from the buccal or lingual surface

2

When wet there is a carious opacity and/or brown carious discoloration and the lesion is still visible when dry. Lesion may be seen when viewed from the buccal or lingual direction. When viewed from the occlusal direction, this opacity may be seen as a shadow confined to enamel, seen through the marginal ridge

3

Once dried for approximately 5 seconds, there is distinct loss of enamel integrity viewed from the buccal or lingual direction

4

This lesion appears as a shadow of discolored dentin visible through an apparently intact marginal ridge, buccal or lingual walls of enamel. This shadow may appear as gray, blue, or brown in color and is often seen more easily when tooth is wet

5

Cavitation in opaque or discolored enamel with exposed dentin

6

Obvious loss of tooth structure; extensive cavity may be deep or wide and dentin is clearly visible on both walls and at the base. The marginal ridge may or may not be present

..      Table 3.5  Description of the ICDAS II codes for free smooth surfaces [20, 88, 99] Code

Description

0

There should be no change in enamel translucency after 5 seconds of air-drying

1

When seen wet there is no evidence of any change in color. After air-drying a carious opacity is visible that is not consistent with the clinical appearance of sound enamel

2

When wet there is a carious opacity and/or brown carious discoloration and the lesion is still visible when dry. The lesion is located in close proximity of the gingival margin

3

Once dried for 5 seconds, there is carious loss of surface integrity without visible dentin

4

This lesion appears as a shadow of discolored dentin, which may or may not show signs of localized breakdown. This shadow may appear as gray, blue, or brown in color and is often seen more easily when tooth is wet

5

Cavitation in opaque or discolored enamel with exposed dentin

6

Obvious loss of tooth structure; extensive cavity may be deep or wide and dentin is clearly visible on both walls and at the base. An extensive cavity involves at least half of a tooth surface or possibly reaching the pulp

..      Table 3.6  Description of the ICDAS II codes for CARS. The details are related to the lesions adjacent to a restoration/sealant margin [20, 88, 99] Code

Description

0

A sound tooth surface adjacent to a restoration/sealant margin. There should be no evidence of caries

1

When seen wet there is no evidence of any change in color. After air-drying a carious opacity or discoloration is visible that is not consistent with the clinical appearance of sound enamel.

2

If the restoration margin is placed on enamel, tooth must be viewed wet. When wet there is an opacity consistent with demineralization that is not consistent with the clinical appearance of sound enamel. The lesion is still visible when dry. If the restoration margin is placed on dentin, discoloration can be seen that is not consistent with the clinical appearance of sound dentin

3

Cavitation at the margin of the restoration/sealant less than 0.5 mm, in addition to either an opacity or discoloration consistent with demineralization (continued)

118

T. M. F. Caneppele et al.

..      Table 3.6 (continued) Code

Description

4

Tooth has a shadow of discolored dentin which is visible through an apparently intact enamel surface or with localized breakdown in enamel but no visible dentin. This shadow may appear as gray, blue, orange, or brown in color and is often seen more easily when tooth is wet

5

Distinct cavity adjacent to restoration/sealant

6

Extensive distinct cavity with visible dentin

3

..      Table 3.7  Description of the ICDAS II codes for root caries [20, 88, 99] Code

Characteristic of the lesion

E

If the root surface cannot be visualized directly, then it is excluded

0

The root surface does not exhibit any unusual discoloration that distinguishes it from the surrounding root areas nor does it exhibit a surface defect at the CEJ or root surface. The root surface has a natural anatomical contour

1

There is a demarcated area on the root surface or at the CEJ that is discolored, but there is no cavitation (loss of anatomical contour > To avoid the overheating and maintain them in adequate working condition, handpieces should be lubricated prior to use with appropriate mineral oil-based lubricants, available in bottles or in spray.

The vibrations and the noise are related to the speed of the turbines and can cause discomfort to the patient and dentist and eventual hearing lesions to the clinician. The vibratory waves can be described according to the frequency and amplitude. The frequency is the number of oscillations in an interval, while the amplitude is the distance between two consecutive wave peaks, and there is a reverse relation between both. When a bur is used on a speed of up to 10,000 rpm, the amplitude is high and the frequency is low, transmitting a higher vibration sensation to the patient. There-

Tip

The rotary movement should always start or stop before the contact with tooth structure. In addition, it should never go in or come out of the mouth with the motor working, because of the risk of hurting the soft tissues.

When the speed of the turbine is superior to 60,000 rpm, the amplitude reduces and the frequency increases. On those situations, the patient stops feeling the vibration of the bur, but begins to notice the noise, which is acute and uncomfortable. The noise can cause shivering and discomfort to the patient and acoustic lesions and psychological lesions to the clini-

4

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S. E. de Paiva Gonçalves et al.

a

b

c

d

e

f

4

..      Fig. 4.21  FG high-speed handpiece associated with a wrench bur remover. a–c Sequence of bur placement; d–f sequence of bur removal

cians, who are exposed to the noise all day long and for many years. Noise above 75 db can cause hearing damage, and turbines of high speed can generate 70 and 94 db [23]. To minimize the deleterious effects of the noises on the patient and the clinician, handpieces with low levels of noise emission should be used. Those should also be used in an intermittent way, in a way that the periods of silence are greater than the periods of noise. The other option is to work with ear protectors while the turbines are being used, which can also be performed by the patient using earphones, for example. The sound reflexes can be attenuated in the clinic using materials that protect from the noise on the floor, walls, and ceiling.

>> To minimize the deleterious effects on hearing, handpieces with low levels of noise emission should be used. Ear protectors are also recommended.

4.3.2

Parts of the Rotary Instrument

The rotary instruments present three parts, and they are the shank, neck, and head (. Fig. 4.22a). The shank is the longest part of the instrument and serves to connect it to the rotary device. To connect to the straight handpiece attached to the low-speed micromotor, the shank is long and smooth. For the  

139 Instruments and Equipments

a

b

c

d

..      Fig. 4.22  a Representation of the parts of the rotary instruments (shank, neck, and head); b types of shanks (1, straight handpieces; 2, contra-angle; 3, high-speed); c types of high-speed rotary instruments

(1, short shank; 2, regular shank; 3, long neck; 4, long shank); d latchtype contra-angle adapter for use of high-speed rotary instruments on low-speed contra-angle

straight attachments/nose cones and Doriot-type low-­speed handpieces, the shank is long, named HP type. For the contraangle low-speed handpiece, the shank is short and has a latch, being called right angle/latch type or RA/CA.  For the highspeed handpiece, the shank is thinner, is shorter, and does not have latches, because the connection happens by friction, being called friction grip or FG (. Fig.  4.22b). There are burs with short, conventional, or long shanks, depending on the necessity of the access (. Fig. 4.22c). The neck, also called intermediary, is the portion between the shank and the head, which is the active part of the instrument. Its length and diameter are vital for the balance of the instrument and consequent transmission of the vibration. It has the function to improve the access and the visibility to the area to be prepared. The metallic alloy that the neck is made of is also very important for the quality of the instrument, because it is subjected to high stress due to its thinner diameter. Its length varies according to the access, the visibility, and the freedom to use the active part of the instrument, and it can be short or long (. Fig. 4.22c). The active part or head corresponds to the functional end of the instrument. The shape and the material from which they are made differentiate its function and the way of action. The high-speed rotary instruments can also be used in low-speed contra-angles, using a latch-type contra-­angle adapter, as it can be seen in . Fig. 4.22d.

4.3.3

 

 

 

 

Types of Rotary Instruments

The rotary instruments used in the cavity preparation to receive a restoration can be classified, according to the way they act, as cutting or abrasive. 4.3.3.1

Cutting Rotary Instruments

It is called a cutting instrument the one that is capable of separating a part of a whole by means of a blade or a sharp edge, which concentrates the force on a small area and results on the propagation of a fracture along the surface touched by the blade, causing the formation of the shavings. The cutting rotary instruments are called burs and can be manufactured in carbon steel, which was the material used on the first rotary instruments, or tungsten carbide which only became available on the market in 1947. The burs have successive blades that when touching the tooth structure remove shavings, similar to what is observed on hand instruments, but on a more efficient way. . Figure 4.23a shows a scheme of a bur blade cutting a substrate and generating the shavings. For the blade to begin the cutting action, it must be sharp and have hardness and elasticity modulus greater than the material to be cut. The high hardness and the elasticity modulus are essential for the concentration of the applied force on a small  

4

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a

b

4

..      Fig. 4.23  a Cutting action of a blade; b cross-sectional scheme of a dental bur and its parts. (Adapted from Phillips [21])

area of the blade’s edge, which must be higher than the shear resistance of the material to be cut [23]. The mechanical distortion of the dental structure due to the blade produces heat, and it is mandatory to use refrigeration, especially in high speed [23]. In . Fig. 4.23b, there is a schematic cross-sectional view of a bur for typical dental use, with six blades, showing the names of the faces and angles. The real cutting action of a bur happens on a very small region on the edge of the blade. Each blade has two sides or faces, and they are the rake and clearance faces. The rake face is on the same direction of the cut, while the clearance face is on the opposite side. They also have three important angles, and they are the rake, edge, and clearance angles. The edge angle usually is not acute. It is around 90° to allow resistance to the blade and increase the longevity and the cut efficiency of the bur. The rake angle is formed between the rake face of the blade and a line that passes through the center of the instrument and the edge of the blade (radius of the bur). It is said to be negative when the rake face is in front of the radius. The scheme of the bur shown in . Fig. 4.23b has a negative rake angle, as most of the burs for dental use, increasing the durability and allowing a good performance in high and low speed. A positive cutting angle would produce an edge angle that is more acute, allowing it to be used only to cut soft surfaces, such as carious dentin. If they were used to cut hard tissues, as enamel or healthy dentin, the edge would quickly become an irregular surface, chip, and dull [25]. The clearance angle eliminates the friction of the clearance face and allows a stop to avoid that the tip of the bur excessively penetrates into the tooth structure, besides allowing the space to the shavings being cleared [23]. The cutting efficiency and the roughness of the resulting surface will depend also on the number of blades. The conventional burs have 6 blades, but this number can vary to 12, 30, or even 40 (. Fig. 4.24a, e, f). The higher the number of blades, the lower the cutting efficiency, but the smoother is the resulting surface. For this reason, the so-called multi-­ bladed burs, that is, the ones with more than six blades, are used for finishing and polishing of the restoration. Before the

a

b

c

d

e

f

 

 

 

..      Fig. 4.24  Burs with different number of blades. a, b Regular bur with 6 blades; c crosscut bur with 6 blades; d bur with 12 spiral blades; e bur with 12 straight blades; f bur with 30 straight blades

development of the high-speed turbines, crosscut burs were very popular, which have transversal cuts on the blades to increase the cut efficiency (. Fig. 4.24c) [25]. This principle is justified by the fact that on crosscut burs, a smaller area of the blade will be touching the surface at the cutting moment, which results on a greater pressure and consequently higher cut efficiency. Nowadays, this bur design is no longer used for cavity preparations, but on burs designated to cut metal, named transmetal burs, indicated to remove metallic restorations. The blades can be disposed parallel to the long axis of the burs on a spiral shape. The spiral disposition results on a smoother surface, even though it reduces the cutting efficiency (. Fig. 4.24d).  

 

4.3.3.2

Abrasive Rotary Instruments

The abrasive rotary instruments are the ones capable of removing material from a structure by the action of friction or fragmentation. They present irregular particles, harder than the substrate to be abraded, deposited on a stainless steel head. During its friction with the surface, it causes frag-

4

141 Instruments and Equipments

a

a

b

c

b

..      Fig. 4.25  Action of an abrasive grinding particle over a substrate. a Ductile materials; b brittle material. (Adapted from Phillips [21])

mentation and consequent grinding (. Fig.  4.25a, b). The grinding happens because of multiple points of individual hard particles that are protruded from the surface, instead of a continuous blade. Those particles have many sharp edges that are randomly oriented over the surface of the instrument head. The material that suffers the abrasion can be classified into ductile or brittle. The ductile materials are less hard and suffer deformation or distention when they are pressed by the abrasive particles. The brittle materials are harder, and they break when they are submitted to tensions. The dentin is an example of ductile material, specially the carious one, while the enamel is brittle. When the abrasive instruments are used over ductile materials, some parts can be removed in chips, but most parts move laterally from the way that is followed by the abrasive particle, forming a type of crest of deformed material on the surface (. Fig. 4.25a). The repeated deformation hardens the distorted material until it becomes brittle, fracturing and removing it. The burs are preferable to cut ductile material, like carious dentin. The interaction of brittle materials with diamonds or other abrasive particles occurs differently. The removal of the material results from fracture by tension which produces subsurface cracks (. Fig.  4.25b). The diamonds are more effective to grind brittle materials and are superior to the burs to remove dental enamel [23]. Examples of abrasive rotary instruments are diamond points, stone points, and the abrasive discs.  

 

 

Diamond Instruments The diamond abrasive instruments or diamond points were developed in 1935. They were fabricated in stainless steel with the shape of heads similar to the burs. Over the head, an agglutinant layer is applied by means of an electroplating process that connects the steel to the diamond particles with different dimensions. This way, when the instrument spins, the irregular diamond particles are rubbed over the substrate, causing the grinding. They represent the class of rotary

..      Fig. 4.26  Diamond points of different particle sizes. a Regular grit; b fine grit; c extra fine grit

instrument that is most used on daily practice, because they can easily grind enamel and dentin. Grinding with diamond instrument should be performed with new points and under refrigeration. The size of the diamond particles electroplated has direct relation with the efficiency of the grinding and the roughness of the resulting surface. The greater the particle size, the more efficient the abrasion will be and the rougher will be the surface. Conversely, the smaller the particles, the smoother the resulting surface will be. In general, six diamond grades can be found on the market, and they are identified by colored rings on the shank, resulting in super coarse (150 μm, black ring), coarse (125 μm, green ring), medium or conventional (100 μm, without a colored ring), fine (30 μm, red ring), extra fine (15 μm, yellow ring), and ultrafine grit (8 μm, white ring) diamond points. The medium grit is the most used on dental preparations. The coarse or super coarse grits are indicated when a great quantity of material need to be removed, such as old restorations. The thin, extra fine, and ultrafine grit points serve to finish and polish the composite resin restorations (. Fig. 4.26a–c). With time, especially if insufficient refrigeration is used, the diamond points can become clogged by the deposit of residues between the diamond particles, which reduces its grinding effectiveness. The clogging is characterized by the presence of a whitish material on the surface of the point that is visible by naked eyes (. Fig. 4.27a). To solve this problem, the point can be briefly rotated over a specific ceramic stone, and the abrasive capacity is restored (. Fig. 4.27b, c). The systematic use of ultrasonic bath to clean the instruments also prevents the clogging. However with prolonged use, the diamond particles will eventually become rounded, or they will debond from the  

 

 

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a

b

c

d

4

..      Fig. 4.27  a Diamond point clogged with residues after abrasion with insufficient refrigeration; b stone diamond instrument cleaning (Limpapontas – KG Sorensen); c the same point shown in A immedi-

a

ately after cleaning; d deterioration of the diamond points (1, new; 2, worn head showing the loss of many diamond particles)

b

..      Fig. 4.28  Mounted stones with different shapes. a Arkansas stones; b silicon carbide stones

agglutinant, reducing the grinding efficiency (. Fig. 4.27d). On the attempt to compensate for the insufficient abrasion, the dentist tends to apply more pressure on the instrument. This can cause overheating of the tooth structure, with risk of damage to the pulp tissue. The diamond points must be ­constantly replaced, and in some countries they are used only once.  

Mounted Stones They are naturally or artificially obtained stones made by hard abrasive agents, mounted on a metallic shank that can be adapted to a straight handpiece, contra-angle, or high speed (. Fig. 4.28a, b). They are indicated for the finishing of restorative procedures performed directly inside the mouth or in laboratory.  

4

143 Instruments and Equipments

The Arkansas stones have white color and are naturally obtained from a rock called novaculite, original from the state of Arkansas (United States). They have been used for centuries to sharpen cutting metallic instruments. Those stones present microcrystalline quartz in its composition, which gives its abrasive property [23]. They present excellent performance, but they cannot be dry sterilized, as they may lose the crystallization water and deteriorate. They must be sterilized in humid heat (autoclave) or chemically. Artificial stones can be made with SiC or aluminum oxide. The SiC stones usually present a greenish color, although some have black color. The aluminum oxide stones can have various colors, as white, pink, beige, blue, and gray, depending on the composition. Besides the abrasive type, they can also vary according to the size of the particles, corresponding to the desired indication. The artificial stones can be sterilized in dry or humid heat. The usual fabrication process requires to carefully press the abrasive particle onto the desired shape and to heat until it becomes solid. To keep the cutting edges of the sharp particles, the fabrication process results on a porous material. The properties of the stones depend on the volume and the size of the pores and on the composition and size of the abrasives that were used [23].

Abrasive-Impregnated Rubber They are rotary instruments with the active head made of rubber, on which many different types of abrasive particles are interspersed such as SiC, aluminum oxide, or diamond powder. The abrasive rubber rotary instruments are used to polish restorations directly in the mouth or in laboratory. Depending on the particle size of the abrasive agent, it allows for a more or less rough surface. In general, they are sold in kits with decreasing abrasivity. Each abrasivity is identified by a different color. They can be used to polish metallic or amalgam restorations, composite resin, or ceramic. The abrasive rubbers are available in various shapes, and the most common are the points (cones), cups, and discs, as those can allow the access to different sites intended to be polished (. Fig. 4.29a–c). Recently abrasive rubber spiral wheels were launched on the market, with the advantage of reaching difficult areas (. Fig. 4.29d). With prolonged use, the tapered points wear off, impairing the access to certain areas of the occlusal surface, such as the cusps  inclines and the bottom of the developmental grooves. Those points can have their shape recovered by gently rotating it over an abrasive surface, as a diamond dresser (KG Sorensen) (. Fig. 4.29e–g), a stone used for sharpening hand instruments, or a SiC disc (. Fig. 11.18a–c). The diamond dresser can also be used to correct the shape of mounted stones, due to the greater hardness of the diamond particles.  

 

 

 

Abrasive Discs The abrasive instruments can also be found on the shape of a disc. They are available in many diameters (1/2, 5/8, 3/4, and 7/8 inches) and require some type of mandrel so they can be used. Many are made using a metallic or plastic disc, over

which an agglutinant and a layer of abrasive are applied. For this reason, they are called abrasive-coated instruments (. Fig. 4.30a, b). The discs made over a plastic base are used for polishing flat surfaces of composite restorations on anterior teeth, while the diamond metallic discs are used in laboratorial work. To create a smooth surface, they are presented in kits of discs in decreasing abrasivity identified by different colors. There are discs made completely by abrasive stone, similar to a mounted stone. They are much used to finish or to cut metallic pieces outside the mouth and are generally called Carborundum discs (. Fig.  4.30c). However, the word Carborundum does not refer exactly to an abrasive material, but to the name of a company founded by Edward Goodrich Acheson in 1891, after he invented the SiC, the first artificial abrasive.  

 

4.3.3.3

Accessory Rotary Instruments

Some rotary instruments frequently used on daily practice are not abrasive by themselves, but are used with abrasive pastes. Among them are some rotary bristle brushes and the rubber and felt instruments (. Fig. 4.31a1–4, b). The brushes present plastic bristles and can have a flat or conic tip, generally named Robinson’s brushes. The rubber instruments can have a conic or a cup shape, while the felt instruments can have the shape of a disc or of a cone. The brushes as well as the rubber cups and cones are used for dental prophylaxis and for polishing of restorations. The felt discs are available in various diameters. They are indicated to polish composite restorations on anterior teeth. The felt cones are indicated to polish the occlusal surfaces of composite resin restorations or on the lingual surfaces of the maxillary anterior teeth. The accessory rotary instruments are used with abrasive pastes such as pumice, calcium carbonate (Spanish white), zinc oxide, aluminum oxide, or diamond, among others, depending on the purpose. As for the other abrasive instruments, to reach a well-polished surface, a sequence of pastes that contain abrasive grains with decreasing sizes must be used, to reduce the substrate roughness on each change. There are some brands of felt discs that already come impregnated with an abrasive agent (. Fig.  4.31b, asterisk), as well as of brushes that already contain silicon carbide abrasive particles on the bristle composition (. Fig. 4.31a, – 5 and 6).  

 

 

4.3.4

 aterials Used on the Fabrication M of Rotary Instruments

The hardness of a cutting or grinding instrument is an essential property. Of course, the cutting instrument must be harder than the substrate. . Table 4.1 shows the hardness of some tissues, abrasives, instruments, and materials involved in dental treatment. Previously, the burs were made of carbon steel because the hardness was almost three times higher than that of the enamel. However, it frequently suffered from oxidation and quick loss of cut. In 1947, the tungsten carbide burs were  

144

a

S. E. de Paiva Gonçalves et al.

b

4 c

d

e

f

g

..      Fig. 4.29  Abrasive-impregnated rubber with different shapes. a Points; b cups; c discs; d abrasive rubber spiral wheels, e rubber point with head worn after use; f sharpening of the rubber point with the diamond dresser (KG Sorensen); g rubber point after the reshaping

145 Instruments and Equipments

a

b

c

..      Fig. 4.30  Abrasive discs. a Abrasive-coated discs; b diamond-­coated metallic disc; c discs made of abrasive stone

a

b

..      Fig. 4.31  Accessory rotary instruments. a Robinson brushes (1 and 2); rubber cups and cones (3 and 4); brushes with bristles impregnated by silicon carbide (5 and 6); b felt discs and cones (∗disc impregnated by abrasive agent)

launched onto the market, with a hardness almost six times greater than the enamel [23]. Those showed a much greater durability and do not suffer from oxidation. Because the milling process of tungsten carbide is difficult and the material is

more brittle, just the head of the bur is made with this material, while the shank is made with stainless steel. The diamond particles present great grinding efficiency as it is one of the hardest materials in nature, about 20 times harder than the enamel.

4

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S. E. de Paiva Gonçalves et al.

..      Table 4.1  Knoop microhardness of some material and tooth tissues [5]

4

Material/tissue

Knoop microhardness

Use

Diamond

7000

Abrasive rotary instrument

Silicon carbide (SiC)

2480

Abrasive rotary instrument

Tungsten carbide

1900

Burs

Aluminum oxide

1500

Abrasive rotary instrument

Carbon steel

890

Burs

Silicon dioxide (silica)

800

Air abrasion

Feldspathic Porcelain

460

Restorative material

Enamel

340

Tooth structure

Stainless steel

300

Hand cutting instruments

Amalgam

120

Restorative material

Dentin

70

Tooth structure

Hybrid composite resin

55

Restorative material

Cement

40

Tooth structure

Microfiller composite resin

30

Restorative material

Silver

30

Restorative material

Gold

24

Restorative material

Acrylic resin

20

Temporary indirect restorations

4.3.5

 asic Shape of Burs, Diamond Points, B and Mounted Stones

a

b

..      Fig. 4.32  Basic shapes of the rotary instruments (1, spherical or round; 2, cylinder os straight fissure; 3, cone; 4, long inverted cone; 5, short inverted cone). a Diamond points; b burs

numbers proposed by the American National Standards Institute/American Dental Association (ANSI/ADA) and by the International Organization for Standardization (ISO 2157), which is related to the shape, diameter, and length of the head, as well as the diameter and length of the shank. It is useful to know the diameters and the length of the bur as a reference to measure the amount of grinding and the distances inside the tooth [25]. The use of each type of bur or diamond point is presented in the corresponding chapters along with the corresponding restorative technique (7 Chaps. 10, 11, 12, 13, 14, 15, 16, and 17).  

The head of rotary instruments is manufactured with some shapes and characteristics to attend specific clinical applications. The basic shapes of the burs, diamond points, and abrasive stones are round (spherical), cylinder (straight fissure), cone (taper or tapered fissure), and inverted cone (short or long) (. Fig.  4.32a, b). The cylinder- and cone-­ shaped instruments may have a flat, round, bevel, or point end. Many other shapes are available, but most are modifications of the basic shapes. Another significant characteristic of the burs and the diamond points is related to the rounding of the corners formed between the end and the sides of the instrument head. This characteristic creates round internal line and point angles on a preparation, which avoids stress concentration, reducing the chances of fracture of the tooth structure. The burs and the diamond points are identified by

4.3.6

 actors Related to the Use of Rotary F Instruments

 

The axial rotation speed of a rotary instrument is the speed that is developed following the longitudinal axis of the instrument. However, when cutting or grinding is performed on any dental tissue, the peripheral speed of the border of the instrument that touches the tooth surface is more important than the axial speed, being called cutting speed. The cutting speed increases as the diameter of the instrument increases. Therefore, a diamond disc of 20 mm of diameter turning on an axial speed of 24,000 rpm will have a peripheral speed on

147 Instruments and Equipments

the cutting edge of 25 m/s. For a bur of 2 mm in diameter to have the same peripheral speed and consequently have the same cutting efficiency, there is the necessity of an axial speed of 240,000 rpm [18, 23]. With the current practice of minimally invasive dentistry, the use of rotary instruments with small diameter became very popular, which makes the use of a high-speed handpiece important so that an adequate cutting or grinding efficiency is obtained [23]. Another very important point in relation to the action of the rotary instrument is the concentricity. It is the symmetry of the instrument head and is related to the neck and the shank. If the head or the bur presents an eccentricity during use, the neck probably is leaned in relation to the long axis of the shank, or the connection of the shank to turbine may have a problem. Any detected eccentricity caused by one of those factors must be solved immediately, because it reduces the cutting effectiveness and produces an irregular cut of the tooth structure and more vibrational effects. This may generate working difficulties to the dentist and great discomfort to the patient. The torque represents the capacity of the rotary instrument to resist the tendency of stopping the movement due to the pressure produced by the contact between the instrument and the cutting surface [9]. The torque is measured in N/cm or g/cm, and the current turbines have a torque of 11–20 g/cm. When the cut or grinding of the tooth structure is performed, part of the kinetic energy from the burs in contact with the tooth is transformed into heat. One must therefore avoid to produce exaggerated pressure with the instrument as it may cause excessive heating and compromise the pulpal vitality. Therefore, the torque level of the handpieces must be limited so that the instrument stops before an exaggerated heat is produced [23]. Besides the cutting pressure, the friction heat has a direct relation to the rotation speed, type, size, quality, and time of use of the cutting or grinding instrument. When it turns more than 4000 rpm, all instruments must be refrigerated to avoid pulpal damage. The recommended refrigeration is with water/air spray that must be directed to the head of the bur. Apart from allowing the dissipation of frictional heat, the refrigeration during the cut acts as a cleansing agent of debris generated during the cut. 4.3.7

jected towards the eyes of the dentist or assistant, causing irritation and even serious damages. This can be avoided with the use of proper safety glasses with lateral protection [22]. Even the individuals that use corrective glasses must wear safety glasses, over the corrective glasses, or use protection glasses with the necessary degree of correction. The aerosol created by the cutting procedures (containing saliva or blood, for instance) can contaminate the dentist and his auxiliary staff, causing cross contamination through the working area and equipment. For this reason, the use of surgical masks is mandatory for the dentist and assistant to avoid aspiration of the contaminants present in the aerosols. It is worth mentioning that the patients can eventually have infectious diseases such as hepatitis, tuberculosis, and meningitis. Another measure that can contribute with the protection of the dentist and assistant is to work under rubber dam  isolation, even during the cavity preparation. The rotary instruments must be sterilized before use. For this reason, some manufacturers produce burs and diamond points for single use that are previously sterilized by gamma radiation. The burs can be sterilized by dry or humid heat or even using antimicrobial solutions. However, the chemical sterilization tends to lead to instrument corrosion. When sterilized in a stove or autoclave, the burs must be positioned in bur block holders, which also allows for better organization and localization during clinical procedures (. Fig. 4.33).  

4.4

Oscillatory Abrasive Instruments

The oscillatory instruments for dental use are metallic shanks with heads covered by diamond and attached to an oscillating device. Instead of producing a rotary movement, they vibrate or oscillate in different directions, promoting the friction of the head with the tooth structure, resulting in grinding. The oscillatory handpieces can work by vibration, as in the cases of sonic or ultrasonic devices, or by back-and-forth reciprocating linear motion, called the EVA system.

Safety Procedures

Almost all procedures that use operatory instruments involve some risk to the patient, dentist, and assistant. This can be related to eye lesions because of particle projection, ear lesions because of the noise, and the constant inhalation of toxic substances or infectious agents. Specifically to the patient, there is the risk of pulpal damage due to heating or accidental exposure, besides soft tissue injuries. However, the use of adequate security measures can reduce most of the risk [23]. During the use of rotary instruments, particles of old restorations and dental fragments can be displaced and pro-

..      Fig. 4.33  Burs block holders for sterilization of the rotary instruments

4

4

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S. E. de Paiva Gonçalves et al.

4.4.1

Oscillatory Handpieces

a

The oscillatory handpieces produce vibrational waves that can generally be classified into mechanical and nonmechanical. The mechanical waves are the ones that propagate in a deformable or elastic environment. As examples, the sound waves, waves on a spring, or waves on the water can be mentioned. They originate from a disturbance in a region of an elastic environment. If the environment has elastic properties, the disturbance is transmitted successively from one point to another. The particles of the environment vibrate only around its position of equilibrium, without a whole displacement. The nonmechanical waves, such as the electromagnetics, do not need a material environment for its propagation. An example is the light, which can go through the vacuum in the interstellar space. The sound waves are characterized by vibrations (variations of pressure) on the air. A healthy human being can hear and distinguish sounds on the approximate range of frequency from 20 to 20,000 Hz. The ultrasound is a sound with a frequency superior to the one that the human ear can notice. The sonic waves are inside the range of human perception, while the waves below 20  Hz are known as infrasound. The researchers noticed that the use of instruments that oscillated in very high frequencies could be useful in many dental applications, as on the removal of calculus or on the cavity preparation. Nowadays, there are two types of vibrational oscillating devices available for dental purposes, and they are sonic and ultrasonic. The oscillating devices with reciprocating movements produce a back-and-forth movement, promoting friction of the abrasive agents with the surface to be worn. 4.4.1.1

Sonic Devices

On the sonic systems, the work is generated from a pneumatic pressure applied internally on an axis supported over rubber rings. The exit of the air happens through the holes that exist on the axis, over which a steel bushing is fixated and will rotate by the pressure of the air, keeping intermittent contact with the external surface of the axis. The turning of the bushing over the axis transmits an oscillatory movement to the handpiece attached to the instruments, with an approximate frequency of 6000–8000 Hz, depending on the brand. Besides the air for propulsion used to rotate the bushing, there is a water connection with exit on the handpiece tip. The refrigerating air jet avoids overheating, keeps the work surface clean, and reduces the sensitivity after the treatment. The movement amplitude of the vibration wave can be adjusted in some devices. The greater the amplitude, the greater is the effectiveness of the grinding. The SONICflex LUX 2003/L (KaVo) device allows that the amplitude is adjusted by the operator to 120 μm (finishing and delicate procedures), 160 μm (cavity preparation), or 240 μm (faster and more aggressive preparations). Other examples of devices are the SONICborden 2000  N (KaVo) and the Cavitador Sonico Air Scaler (Microdont) (. Fig. 4.34a, b).  

b

..      Fig. 4.34  Sonic devices for the cavity preparation a SONICborden 2000 N (KaVo); b Air Scaler (Microdont)

4.4.1.2

Ultrasonic Devices

The work in ultrasonic devices is generated by transducers. Briefly, the transducer is a device that converts one type of energy into another. The ultrasonic transducers convert electrical energy into mechanical energy. There are two types of transducers that can produce ultrasonic movement, the magnetoelectric or magnetostrictive as well as the piezoelectric systems. The magnetostrictive system consists of the passage of electricity over special metallic blades, creating vibrations and producing heat during the use, which requests more refrigeration. This technology was used on the first-­generation devices. The piezoelectric effect was discovered by Pierre and Jacques Curie, in 1880, and it consists of a variation on the physical dimension of specific crystalline materials that were subjected to electrical field. When a piezoelectric material is put into an electrical field, the electrical charge of the crystalline net interacts with it and produces mechanical tensions. The quartz and the tourmaline, natural crystals, are piezoelectrics. However nowadays, special ceramic chips made of polycrystalline lead zirconate titanate (PZT) are used on these devices. The crystal to be used as a transducer must be cut in a way that an alternated electrical field, when applied on it, produces variations on its width. Those variations produce a movement of the faces of the crystal, originating sound waves. Each transducer has a natural resonance frequency so that the smaller the thickness of the crystal, the greater the vibration frequency. Most of the ultrasonic devices available in the market use a piezoelectric system (. Fig. 4.35). It is important to mention that patients and dentists that have a heart pacemaker should not use ultrasonic devices, due to undesirable interferences that they can produce to the heart’s rhythm. This problem is more critical with the use of magnetostrictive devices, but on a safer way, it is wise to advice clinicians and patients who have a heart pacemaker not to work with nor undergo treatment with any ultrasonic device [17].  

4.4.1.3

Reciprocating Movement Devices

These devices use a working principle called the vertical reciprocating action, which is based on the conversion of the rotary movement of the turbines on a back-and-forth movement, repeated many times in a continuous way. The ampli-

149 Instruments and Equipments

..      Fig. 4.35  Ultrasonic device (CVDent 1000 – CVDentus)

..      Fig. 4.36  Handpiece of the EVA system (Ti-Max – NSK)

tude of this movement can vary from 0.8 to 1.4 mm, depending on the brand of the device, and is known as the EVA system. They promote a grinding action similar to a sandpaper, but on a much smaller scale. It can be associated with many types of diamond or plastic points, for different applications, such as for finishing and polishing or cavity preparation. The most common type is the point with the pyramidal section, similar to a wooden wedge, that adapts into interproximal spaces to polish or remove restoration overhangs. The contra-angle EVA Prophylactic Head (KaVo), Ti-Max EVA (NSK), and EVA-F (Brasseler) are examples of this technology (. Fig. 4.36).  

4.4.2

Types of Diamond Points

The diamond points used in sonic or ultrasonic oscillating devices can be made by agglutination of natural diamonds, similar to a rotary diamond point, or by deposition of the newly formed diamond directly onto the shank. 4.4.2.1

Points with Agglutinated Diamonds

The diamond points for use in oscillating devices can have many different shapes, depending on the desired clinical application, as it can be observed in . Fig.  4.37. On these points, the natural diamond particles are bonded to the metallic head by means of an electroplating process. The SONICflex LINE Tips kit, produced by the KaVo company (Germany), is recommended for the use in sonic devices. It has many points for various applications in operative dentistry, such as the preparation of minimally invasive occlusal cavities, proximal surfaces with difficult access, removal of carious tissue, or the preparation of marginal bevels. It can also be used in the preparation of indirect restorations, where the buccal and lingual walls of the proximal boxes need to be prepared with an ideal angulation and standardized cavosurface margin (. Fig. 15.11a–h). The recommended points for proximal surfaces present diamond deposition on only one side, which avoids the undesired grinding of the adjacent tooth. The EMS company (Switzerland) also produces points  

 

..      Fig. 4.37  Diamond points with various shapes produced by agglutination of diamond particles (SONICflex LINE Tips – KaVo)

with agglutinated diamonds in many shapes to be used in ultrasonic devices, while the Intensiv company (Switzerland) produces many points with agglutinated diamond to use with the contra-angle of reciprocating action on the EVA ­system. 4.4.2.2

Points with Deposited Diamonds (CVD)

Another alternative for the manufacturing of diamond instruments is the deposition of artificial diamonds directly over the metal head of the instrument, through a process called chemical vapor deposition or CVD. The points made by this process were developed by the DIMARE (Diamonds and Related Materials) group from the National Institute of Space Research (INPE) in Brazil, based on experiments that produced the columnar growth of diamonds on metal threads with a small diameter [27]. The CVDVale company patented this technology for dental use in ultrasonic device,

4

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a

b

4

..      Fig. 4.38  Microscopic image of the CVD diamond point surface a, in comparison with a point with agglutinated diamonds b

and the points were launched onto the market in 2001. The metal heads of CVD points are made of molybdenum. The vapor chemical deposition happens due to methane and hydrogen gases inside a reactor, under vacuum and high temperature. Those points have a thick and well-bonded layer of diamond on the active head, without the need of an agglutinant for connection (. Fig. 4.38a, b). They are very durable, resisting to the ultrasound vibrations when grinding hard materials. The points have various shapes and grits and work together with the adapters that promote the connection with the ultrasonic devices (. Fig.  4.39a–c). They are indicated for cavity preparation, removal of amalgam or composite restorations, and bone grinding. The many shapes and angles allow for adequate use in different applications. As these points promote the grinding through vibration, they do not require long-axis symmetry and balance. This allows the production of heads with flat shapes or with multiple angles, improving significantly the access to remote sites. The use of diamond instruments with the ultrasonic device, on the range of frequency between 25,000 and 35,000 Hz, produces changes on the structure where the waves propagate. The particles of the environment where the waves are applied are energized, causing vibration and transmission of energy also in the form of waves to the adjacent particles [3]. In the liquid environment, the waves are transmitted and dissipated with little resistance, causing the formation of air bubbles (. Fig. 4.40). When the ultrasonic technology is clinically used for grinding of the tooth structure or in the removal of old restorations, significant differences in relation to the use of rotary high-speed handpiece are noticed. These include the  

 

 

pressure applied, the direction of the grinding head, and the use of a continuous contact with the tissue or substrate. In relation to the pressure applied, while on the rotary highspeed instruments, the increase of pressure increases the removal of the structure; with the sonic and ultrasonic points, the increase of pressure significantly decreases the grinding effectiveness. That increases the working time and reduces the durability of the instrument. This is attributed to the fact that the pressure applied by the dentist on the handpiece counteracts the anterior-­posterior vibration that naturally happens on the device, decreasing the effectiveness of the grinding. The ideal pressure for the handling of an ultrasonic device is the weight of the handpiece itself, avoiding an extra pressure from the operator. The reduced pressure is considered to be a factor that contributes to the reduction of tooth sensitivity during the use of ultrasonic points [14]. Some studies demonstrated that the use of ultrasonic devices for cavity preparation is more comfortable for the patient. It allows for a psychological reprogramming and an improvement of the pain threshold, when compared to the use of high-speed rotation, reducing the need of anesthetics in some procedures [10, 15]. The reduction of sensitivity should not reflect in complete elimination of the anesthetic procedure. The variations among patients in relation to the pain threshold, the psychological preparation, and the depth of the cavity preparation should be taken into consideration on the choice of treatment. Besides reduced pressure, lower teeth sensitivity can be due to reduced dentinal fluid movement and heating of the tooth structure. This is because in CVD devices, the water used in irrigation slightly warms up as it passes through the handpiece, avoiding thermal discomfort to the dentin [7, 14, 28]. An in  vivo study has compared the dentin-pulp complex

151 Instruments and Equipments

a

b

c

..      Fig. 4.39  Points with various shapes with CVD diamonds. a Regular grit; b fine grit; c adapter for the CVD diamond point to connect the device

..      Fig. 4.40  Formation of bubbles during the use of the ultrasonic diamond points

response between the use of CVD point for ultrasonic device and the diamond point for high-speed handpiece in human molars. It concluded that none of the systems caused significant changes to the odontoblastic layers [7]. The abrasion speed of the CVD systems is slower than the rotary instruments. Therefore, procedures that require the cut of big amounts of substrate, such as prosthetic tooth

preparations, removal of metallic or ceramic prosthesis, or endodontic access, are not indicated for ultrasonic points [14]. The ultrasonic system presents an average of 2 minutes longer working time in comparison to the rotary high-speed handpiece [8]. However, amalgam restorations become loose during removal with the ultrasonic device, which turns the work easier. All the points have a 60° angulation, and some models have double angulation. Under the action of the ultrasonic device, the active end vibrates back and forth on the same plane defined by the point. This movement results in areas with distinct grinding effectiveness around the head. The anterior and posterior areas of the head cause a greater impact and faster grinding over the surface to be worn than the sides of the head. Both lateral surfaces are in a perpendicular plane to the anterior-posterior movement generating no impact. The oscillations of the sides produce a more characteristic movement of polishing, resulting in a smoother surface. In a comparative evaluation, moving the head forward grinds out faster than backward. In general, the most efficient grinding happens when the device is moved toward the head side. To increase the efficiency of grinding, the head must be constantly moved, but this movement cannot be associated with pressure. To start a cavity preparation, the movement must begin with slight

4

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pressure and circular movement, for the tip of the head to achieve a more effective grinding. However, to enlarge the cavity, an anterior-posterior movement must be used, also with a slight pressure and avoiding the lever movement. Another advantage of the use of the ultrasonic device is its selective grinding. It only works on hard tissues, without harming the soft tissues. That is why no harm or bleeding of the lips, cheeks, and tongue, as well as no piercing of the rubber dam, polyester matrix strips, or gauze and cotton rolls, is usually observed. 4.5

Complementary Instruments

Most of the complementary instruments to the restorative procedures are similar in appearance to the hand cutting instruments, but with differences in the blade. The amalgam carver, for example, has blades for sculpting instead of blades for dental cutting. For the non-cutting instruments, the blade is replaced by nibs with various applications. In the amalgam condenser and burnisher, the blade is replaced by flat and dull nibs, respectively. Special spatulas are used for mixing materials and others to carry the protecting or restorative materials into the cavity. Other complementary instruments include the clinical mirror, exploratory probes, tweezers, and pliers, besides the anesthetic syringe and small pots, as presented here [25].

a

4.5.1

Clinical Mirror

For the procedures performed in the mouth, it is important that the dentist has a perfect vision of the operating field. Whenever possible, the direct vision must be used. However, in specific areas of the mouth, the indirect vision obtained with a clinical mirror is the only option to allow for an adequate visualization of the operating field. The indirect vision helps clinicians to keep a correct work posture, without the need to lean the body forward or sideward. The mirror also allows for light reflection, which helps illuminate the area that is being examined or treated [25]. The clinical mirror also serves to put away the cheeks, tongue, or lips to aid for the access and visualization [25]. For clear vision, the reflexive surface of the mirror must be above the glass, on the so-­ called first-surface mirror (. Fig.  4.41a). Some mirrors present the reflexive surface under the glass, which is called the second-surface mirror, resulting in distortions and double and less clear images (ghost images and waviness) (. Fig.  4.41b). To differentiate both types, an instrument should be put in contact with the mirror (. Fig. 4.41a). If the instrument touches the image, it is a first-surface mirror. Clinical mirrors have a circular shape and are presented in several sizes, related to determined reference numbers (3–1.95 cm, 4–2.23 cm, and 5–2.43 cm). The most commonly used in adults are the numbers 4 and 5. For the areas of hard access or for children, the number 3 can be useful  

 

 

b

c

..      Fig. 4.41  a First-surface mirror; b second-surface mirror; c clinical mirror with different sizes

4

153 Instruments and Equipments

a

b

c

d

e

f

g

a b

c

d ..      Fig. 4.43  Exploratory probes. a–c Straight probes; d, e curved probes; f inactive end probe; g straight probe with bended end

..      Fig. 4.42  Different types of tweezers and forceps. a, b Clinical tweezers; c Miller articulating paper forceps; d Halstead mosquito forceps

a

b

c

d

(. Fig. 4.41c). Most mirrors have flat surfaces creating a 1:1 sized image, while others have a concave surface, which slightly increases the image size [25].  

Tweezers and Forceps

4.5.2

The tweezers are other indispensable item in the routine of a dentist. The clinical tweezer is useful to hold small items, such as cotton rolls, and carry them into the mouth (. Fig.  4.42a, b). Another very useful instrument is the Halstead hemostatic mosquito forceps, which is similar to a tweezer but with a lock, and is used to firmly insert or remove items, such as the interproximal wooden wedges (. Fig. 4.42d). The Miller articulating paper forceps was created to bring into the mouth the articulating paper, in between the dental arches, to mark the contact between opposing teeth (. Fig. 4.42c).  

 

..      Fig. 4.44  Different types of spatulas. a Spatula No. 22; b spatula No. 50; c spatula No. 24; d spatula No. 36

 

Exploratory Probe

4.5.3

4.5.4

The exploratory probe or dental explorer is a pointed instrument used for tactile examination of irregularities on the tooth surface and restorations, and determination of the consistency of tissues. The most used type has the shape of a hook (. Fig. 4.43e). Another common type presents a straight end with a fold in a straight angle (. Fig. 4.43g). In general, these two tips are associated with the same instrument. Another useful probe is known as “cow horn” or “pigtail” (. Fig.  4.43d). There are also probes with straight end for endodontics (. Fig. 4.43a–c) or probes with dull end for checking the root surfaces, on the diagnose of carious lesions or periodontal disease (. Fig. 4.13f). Most of the instruments available in the market are double-ended, presenting different tips on each side.  

 

 

 

 

Mixing Spatula

A great variety of restorative materials need to be mixed with a spatula, over a paper block or a glass plate, before use. The spatulas are available in different sizes and thickness, depending on the application (. Fig. 4.44a–d). The large spatulas are used to mix large amounts of materials, while the small ones are for reduced quantities, such as in the case of protective lining materials. Small spatulas have also been used to mix small quantities of resin cements. The thin spatulas are more flexible than the thick ones, and the choice between one over another depends on the material to be mixed [25]. The zinc oxide-eugenol cement, for example, needs a more rigid spatula, while the glass ionomer cement is easily mixed with a flexible spatula.  

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4.5.5

Instrument for Filling and Modeling

­ seful to smoothen up the superficial layer of esthetic restou rations (. Fig. 14.38u). The retraction cord packing instruments are available with straight or round edge. Their thin edges and fine serrations sink into the cord, preventing it from slipping off and reducing the risk of cutting the gingival attachment (. Figs. 4.46a and 14.44c). Finally, another instrument that is used for applying protective materials is the calcium hydroxide liner placement instrument (. Figs. 4.46b and 9.18g). It presents a tiny sphere on the nib that retains the material, which can be precisely applied in areas of difficult access. This instrument is also commonly used for the application of GIC.  

The plastic filling instruments are used for carrying materials into the cavities and sculpting composites or GIC, to restore the shape of the damaged tooth structure. Various options are available, made in many shapes and with different materials (. Fig. 4.45a). The most used instrument has two paddle-­shaped flat ends, in perpendicular directions, which are very useful to shape anterior restorations (. Fig.  4.45a). Some instruments are also covered with a non-sticking coating of titanium nitride of golden color (. Fig. 14.47k). Different combinations are available for double-ended instruments, such as a flat nib on one side and a plugger or a small sphere on the other side, that help to adapt the material into cavities with difficult access (. Fig. 14.47j). In addition, those instruments are also used to help the rubber dam placement and for the insertion of gingival retraction cords. There are also sculpting instruments with silicon nibs, which present the advantage of being non-sticky (. Fig. 4.45b, c). Other instruments that are very useful for modeling resin composites are special brushes with tips in various shapes. The best ones are made of natural Kolinsky fur or synthetic materials (. Fig.  4.45d). The flat brushes are particularly  

4

 

 

 

 

 

 

 

4.5.6

The condensers or pluggers are instruments used to condense and adapt the amalgam toward the walls of a cavity preparation (. Fig. 11.6j, k). Their nibs are flat and generally circular in cross section, even though some models can also be rectangular- or diamond-shaped. There are basically three types of condensers, the ones developed by Black have a cylindrical nib, while the ones developed by Hollenback have coneshaped nibs. The pluggers created by Ward have inverted  

a

b

c

d

..      Fig. 4.45  a Many types of plastic filling instruments for sculpting composites; b instruments with silicon tips (silicon brush – Micerium); c silicon sculpting instruments (Esthetics Plus, TDV); d brushes with

Condensers

different shapes (on the left the Kolinsky fur and on the right synthetic fur – Kota)

4

155 Instruments and Equipments

a

b

..      Fig. 4.46  a Retraction cord packing instruments; b calcium hydroxide liner placement instrument

a

b

..      Fig. 4.47  Amalgam condensers. a Ward; b Black

cone-shaped nibs (. Fig. 4.47a, b). The pressure of condensation is related to the force applied by the operator and to the diameter of the nib. The small ones result in more pressure and are ideal to condense the material in places of difficult access, such as retention areas. The large nibs are used to condense large amounts of material on the occlusal surface.

a

 

4.5.7

b

c

d

e

f

g

h

Carvers

The carvers are used to shape amalgam restorations (. Fig. 11.6y). The blades must be kept sharp to provide effective 

ness. The most used carvers are the No. 3 and No. 3S (Hollenback carvers), the discoid (on the shape of a disc) and the cleoid (claw-shaped), the set of instruments developed by Frahm, and the interproximal carver (IPC) (. Fig. 4.48). The use of each instrument depends on the site and type of anatomy to be reproduced, besides individual preferences during the use. More details will be provided in 7 Chap. 11.

..      Fig. 4.48  Amalgam carvers (a IPC; b, c and d Frahm set; e discoid; f cleoid; g Hollenback 3; h Hollenback 3S)

 

 

4.5.8

Burnishers

The burnisher is an instrument that has a dull nib with many shapes. It is used by rubbing the nib on the surface of amalgam restorations, before and after carving, to improve con-

densation of the material and create a smoother surface (. Fig. 11.6h, i, j). . Figure 4.49 shows examples of different burnishers.  

4.5.9

 

Intraoral Carriers

Intraoral carriers are instruments used to carry material into the cavity preparation, similarly to a syringe. They have a

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cannula with a circular cross section, where the material is compressed, and an embolus that when pressed pushes the material out. There are many models available in the market, depending on the desired application. . Figure 4.50a shows carriers for silver amalgam, while . Fig. 4.50b shows carriers for powder materials, such as calcium hydroxide pro-analysis (PA) and the mineral trioxide aggregate (MTA).  

 

4

4.5.11 

Matrix Retainer

The matrix retainers are instruments designed to hold a metallic strip, called matrix band, used to give contour to restorations at the proximal surfaces (. Fig. 8.2a). There are many types available in the market, as it can be observed in . Fig.  4.52a–c. More details are presented in 7 Chap. 8.  

 

 

4.5.10 

Scissors

The scissors are used in operative dentistry for many purposes, such as to cut matrix strips, rubber dam, and retraction cords. The most commonly used scissors are with a fine tip also called Iris scissors. These can reach areas of difficult access inside the mouth, as in the moment when the septum of rubber dam in the interproximal spaces needs to be cut, to remove the rubber dam isolation. The Iris scissors have this name because they were originally designed for the fine detail work of ophthalmic surgery. There are also the so-called scissors for gold, used in the past to cut gold foil for direct restorations. Both types can present straight or curved ends, depending on the application (. Fig. 4.51a, b).

4.5.12 

 lamps, Clamp Forceps, and Rubber C Dam Punch

The clamps are instruments designed to adapt to the cervical area of the tooth, allowing the fixation of rubber dam in a rubber dam isolation (. Fig.  4.53a). Clamps are taken to position by clamp forceps, as it is shown in . Fig. 4.53b. The rubber dam punch forceps is an instrument used to open holes on the rubber dam (. Fig. 4.53c). More details are presented in 7 Chap. 7.  

 

 

 

 

a

b

c

d

a

b

..      Fig. 4.49  Amalgam burnishers (a egg shape; b Bennett; c ­Hollenback No. 6; d Clev-Dent burnisher)

..      Fig. 4.51 Scissors. a Iris scissors; b Scissors for gold

a

b 1 1 2

2 3

..      Fig. 4.50  a Amalgam carriers (1 10A-PF, Duflex; 2 12A-H, Duflex; 3 S.S. White model, Duflex); b powder material carriers (1, MTA carrier, Angelus; 2, MTA 010 M carrier, Golgran)

4

157 Instruments and Equipments

a a

b b

c

..      Fig. 4.54  a Flat-nose plier; b riveting pliers

c

..      Fig. 4.52  Matrix retainers. a Tofflemire; b Ivory; c Siqveland

d

e

b a

a

b

f

..      Fig. 4.55  Dappen dishes. a Glass; b plastic; c silicon; d plastic with lid; e stainless steel with lid; f Teflon coated

prepare a custom-made matrix and its use is explained in 7 Chap. 12 (. Fig. 12.15a–o).  

 

4.5.14 

Dappen Dishes

Dappen dishes are very useful pots that retain relatively small quantities of materials, such as abrasive agents, gels, solutions and adhesives, used during the restorative treatment. Dappen dishes can be made of glass, plastic, silicon, or even metal, in many shapes, with or without lids (. Fig. 4.55a–f).

c

 

4.5.15 

..      Fig. 4.53  a Clamps; b forceps for clamps; c Ainsworth rubber dam punch

4.5.13 

Some pliers can have a very important role in restorative procedures, helping to adjust the clamps (7 Chap. 7) or to bend the matrix strips, as it is the case of the “flat-nose” pliers (. Fig.  4.54a). The riveting pliers (. Fig.  4.54b) are used to  

 

The carpule syringe or dental syringe is used to inject local anesthetics, which allows for the control of pain during treatment. It presents a system that allows adaptation of the dental carpules, which are small cylindrical tubes containing dental anesthetics, and needles of small diameters which are screwed onto dental syringes (. Fig. 4.56 – 1, 2, and 3).  

4.6

Pliers

 

Carpule Syringe

Vision Magnifiers

The quality of work performed by the clinician has direct relation with the capacity to clearly visualize the operating field. Therefore, devices that amplify the vision are very useful in restorative procedures. Among the vision magnifiers, there are the dental loupes, which are attached to the head of

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S. E. de Paiva Gonçalves et al.

the dentist or on their glasses, allowing for a magnification of up to four times the size of the original image (. Figs. 4.57a and 2.17f). Dental loupes with greater magnification capacity are generally heavy and can restrict head movement and impair the stability of the vision field. In the 1970s the use of the dental operating microscope has been introduced in dentistry. Despite the name, the device does not allow for microscopic observation of objects, providing a magnification that can range from 3 to 20 times [18]. Similar instruments for laboratorial use are known as stereomicroscope (. Fig. 4.57b). The use of the microscope allows the dentist to work on a more ergonomic posture. Moreover, some models transfer the images on to a screen and are able to record the dental procedure on a personal computer.  

4

 

Tip

There are some loupe systems associated with headlights, which facilitates visualization of the working environment.

4.7

Airborne-Particle Abrasion

speed by air blow of high pressure. The friction of the particles with great kinetic energy on the tooth surface promotes an abrasion. In the 1940s, an electrical abrasive instrument called Airdent, manufactured by the S.S.  White company, was launched onto the market to be used on cavity preparations. However, at the time, all the restorations needed a defined geometrical shape, which could not be obtained with this technology. For this reason, its use was abandoned. With the popularization of the restorative adhesive materials in the 1980s, the device was reintroduced to the market and it was better accepted [25]. One advantage of this method is the absence of vibration and noise, which is a characteristic of the high-speed handpiece, besides allowing minimally invasive cavity preparations. Large particles (50 μm) can be used to promote a faster grinding, while small particles (27 μm) are recommended to promote a slower grinding. One disadvantage of the previous devices was that they generated a lot of dust, because of the spreading of particles and debris in the oral environment. In the more modern devices, the powder jet on the center of the tip is surrounded by a water jet, which allows for less contamination of the environment with the powder. Airborne-particle abrasion devices are available as independent units or attached to the compressed air outlet of the dental delivery units (. Fig. 4.58a, b). Some devices can slightly heat the water to decrease the discomfort caused by the thermal shock, in the cases where anesthesia is not being used.  

The technique of airborne-particle abrasion consists of the use of abrasive aluminum oxide particles expelled in high

4.8

..      Fig. 4.56  Disposable needle (1), carpule syringe (2), and dental carpules

a

Laser

The word LASER is an acronym for light amplification by stimulated emission of radiation. The light is electromagnetic energy which moves through space, with specific characteristics according to the wavelength. As examples of electromagnetic waves with different wavelengths, from the smallest to the greatest, there are the gamma rays, the X-rays, the ultraviolet, the visible light, the infrared, the microwaves, and the radio waves. On the so-called visible light, the wavelength can vary from 390 to 770 nm, being

b

..      Fig. 4.57  Vision magnifiers. a Dentist using dental loupes during clinical procedure; b dental operating microscope

159 Instruments and Equipments

a

b

..      Fig. 4.58  Air abrasion device. a PrepStart H2O (Danville); b air abrasion handpiece – RONDOflex (KaVo)

captured by human eyes and identified by the brain as various colors. Each color corresponds to a range of wavelength. However, the emitted light by the laser presents peculiar characteristics, different for example, from the solar light or from the ones that come from a conventional bulb. The laser light has monochromaticity, collimation, and coherence [26]. The first of them is related to the color. While in the white light coming from a light bulb there is a mixture of many different wavelengths, on laser there is only one wavelength and color, being called a monochromatic light. . Figure  4.59a shows a schematic representation of the white light and laser passing through a prism. The white light is separated in its different wavelengths, while the laser does not separate. In addition, the regular light waves travel in different directions, while in the laser all the waves travel on the same direction, forming a collimated beam (. Fig.  4.59b). The third characteristic of the laser corresponds to coherence. It means that the many waves that compose the beam are emitted in a way that its crests and valleys coincide (. Fig. 4.59c). The theory of stimulated emission of radiation was proposed by the physicist Albert Einstein in 1917. However, it was only converted into reality by the studies of Charles H. Townes in 1950, by means of amplification of the microwaves with the MASER device, and by Theodore Maiman in 1060, when the first laser equipment was built with the ruby crystal [11]. The emission of the light from laser devices happens by a quantum process. It is known that the atoms present a nucleus, composed of protons and neutrons, and are surrounded by the electrosphere. On it the electrons are disposed on energetic sublevels. The closest to the nucleus an electron is orbiting, the less energy it has, and it is said on the fundamental state. If this atom receives energy from an external source, the electron goes to a more external sublevel, entering to what is called an excited state. In normal situations, this electron will not be able to maintain this state and will return to the fundamental state. Therefore, the absorbed energy is eliminated as a photon, which is a packet of energy. This process is called spontaneous emission of radiation.

a

WHITE LIGHT

 

LASER b

 

 

c

..      Fig. 4.59  Characteristics laser light. a Monochromaticity; b collimation; c coherence

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In the laser devices, the atoms that are responsible for the light generation are named active laser medium, and they are in an environment which can be solid (crystal), liquid, or gas. When it receives energy from an external source, the electrons of those atoms pass to an excited state. However, before they eventually return to the fundamental state, they receive more energy, so it causes the electron to be forced to return to the most internal sublevel, releasing now two exactly similar photons by stimulated emission, with the same wavelength and coherence. Therefore, on a process of stimulated emission, there is a type of cloning of photons, increasing the quantity of similar photons. The active medium is built between two mirrors in a device called optical resonator, in a way that only the photons that travel in the same direction are used, allowing the beam to have a collimation [26]. Depending on the material used as an active medium, many wavelengths can be produced. The active medium is mixed with the other materials that compose the environment where the light is produced. For example, in the ruby laser developed by Maiman, the ruby is a crystal of aluminum oxide that contains a little chromium inside, and the chromium is the active medium. On the helium and neon gas lasers, the neon atoms are the ones that generate the characteristic red light. Therefore, the active medium gives the name to the laser. Each type of active medium is capable of generating a specific wavelength, and it can be part of the visible or non-visible spectrum of light, such as the ultraviolet or the infrared [23]. The laser can be emitted continuously or in a pulsing way, in an attempt to control the heat produced. Depending on the power output, the devices can be classified into high- or low-power laser (. Table 4.2).

Depending on the characteristics of the target tissue, different interactions between the laser and the substrate can happen. The laser light can be reflected by the surface of the material it hits, be transmitted through it, spread on its interior, or be absorbed. What determines which effect will take place is the characteristics of the substrate. The most important biological effects happen when the light is absorbed, where the light energy is converted in heat, on the so-called photothermal effect. Depending on the quantity of heat generated, the laser energy can be used to coagulate or vaporize the tissue. For the light to be absorbed, the spectrum of the laser emission has to coincide with the peak absorption of the target tissue. However, even when the heating is low, biological effects called photochemicals may also occur. . Table  4.3 shows the effect of different temperatures over the tissues.  

..      Table 4.3  Temperature and respective effect over the biological tissues Temperature

Effects

37–60 °C

Heating, absence of visual change

60–100 °C

Denaturation of the protein and coagulation, shrinkage of the tissue, hemostasis

Above 100 °C

Vaporization, disintegration of the tissue, cut, ablation

Above 400 °C

Carbonization of the organic materials, melting and crystallization of the inorganic material

 

..      Table 4.2  Types of laser, active medium, power, wavelength, and operational mode Type

Active medium

Power

Wavelength (nm)

Mode

Infrared

CO2

High

10,600

Continuous

Er,Cr:YSGG

High

2780

Continuous/pulse

Er:YAG

High

2940

Continuous/pulse

Ho:YAG

High

2060

Pulse

Nd:YAG

High

1064

Continuous/pulse

Diode laser (GaAlAs)

Low

850

Continuous/pulse

Diode laser (GaAlAs)

Low

650

Continuous

HeNe

Low

633

Continuous

Argon

High/low

514; 488

Continuous

XeF

High

351

Pulse

XeCl

High

308

Pulse

KrF

High

248

Pulse

Arf

High

193

Pulse

Visible

Ultraviolet

161 Instruments and Equipments

The effects of the laser depend on its power and how the irradiated tissue interacts with this energy. Therefore, the equipment that generates low power can promote nonthermal effects, such as an analgesic and anti-inflammatory action, and the stimulation of the tissue repair. On the analgesic effect, it acts from the peripheral receptors up to the stimulus on the central nervous system. The anti-­inflammatory and antiedema effect results from the acceleration of the microcirculation, promoting changes at the capillary hydrostatic pressure, with reabsorption of the edema and the elimination of the deposit of intermediate catabolites. In addition, the low-power laser also increases the cell functions on the irradiated tissues, accelerating the time for mitosis. This is mainly observed on the scarring repair of the lesion because of its greater vascularization and abundant formation of granulation tissue. As examples of the low-power devices, there are the HeNe (helium-neon) laser and the low-power diode lasers that emit on the visible red or on the infrared spectrum [11, 24, 30]. They are used in operative dentistry for the treatment of the tooth hypersensitivity and on cases of pulpal inflammation. On the other hand, the high-power devices are used in cutting and for coagulation and vaporization of tissues in medicine and dentistry, besides other industrial applications [12, 30]. The most used high-­power lasers over the tooth structure are the erbium:yttrium aluminum garnet (Er:YAG); erbium, chromium:yttrium, scandium, gallium garnet (Er,Cr:YSGG); and neodymium:yttrium aluminum garnet (Nd:YAG). 4.8.1

Erbium Lasers

a

b

The Er:YAG and Er,Cr:YSGG are solid-state lasers, where the active medium is formed by erbium or erbium and chromium atoms, inside a synthetic crystalline material of the garnet group, composed of yttrium and aluminum (YAG) or yttrium, scandium, and gallium (YSGG). The Er lasers have an excellent interaction with tooth tissues due to the ­wavelength of 2.79 and 2.94 μm, which coincides with the maximum absorption of water, commonly available in biological tissues. Those lasers are also absorbed by collagen and hydroxyapatite available in the tooth structure. When absorbed, a great quantity of energy concentrated in a very small area of the tissue causes an immediate evaporation of water content. This results in an abrupt expansion, leading to a small explosion that mechanically eliminates pieces of the tissue, called photomechanical ablation [2, 13]. The Er lasers are indicated for cavity preparations. This device has red light guide since the erbium laser is not on the visible spectrum (. Fig.  4.60a, b). The standard handpiece works without contact and must be adjusted by the operator to the correct distance (. Fig. 4.60b). Innumerous researches demonstrate that the energy used must vary according to the tissue to be irradiated and the effect that is  

 

..      Fig. 4.60  Er:YAG Laser device (Key III – KaVo); b handpiece for cavity preparations

desired. The enamel is a more mineralized tissue and requires more energy for ablation, while the dentin requires less energy to produce ablation [11, 30]. A significant difference in relation to the preparation with rotary instrument is that laser does not produce smear layer, leaving a clean ­surface (. Fig. 4.61a–d).  

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a

b

c

d

4

..      Fig. 4.61  Tooth surface treated with Er:YAG laser. a Aspect of a laser pulse over enamel; b greater magnification of the prepared enamel surface; c aspect of a laser pulse over dentin; d greater magnification of the prepared dentin surface

163 Instruments and Equipments

4.8.2

Nd:YAG Laser

a

This laser uses as an active medium the neodymium atoms inside a solid matrix composed of a crystal of yttrium and aluminum garnet, emitting a wavelength on the infrared region of 1.064 μm (. Fig. 4.62a, b). This laser is used in dentistry due to its cutting, vaporization, and coagulation properties, mainly on soft tissue surgeries. When applied over the tooth structure, it promotes the melting and the recrystallization of the surface, producing an antimicrobial effect. Therefore, it is used for sealing the grooves and the fissures and on the disinfection of root canals. However, since there is no refrigeration, depending on the energy used, it can cause carbonization of the tissue or even an undesired effect on the adjacent soft tissues. The light is applied by means of an optical fiber. Because it is not visible, it also uses low-power red laser as a guide light (. Fig. 4.62b). The application of the Nd:YAG laser before the application of adhesive systems has shown to cause negative effects on the bond strength. It impairs the penetration of the adhesive into the tooth substrate (enamel/dentin) as laser melts the tissue, making it more resistant to the acid etching (. Fig. 4.63a–d). However, favorable results were observed in some studies, when the laser was applied after the etching and the application of the adhesive system, prior to light curing [1, 12, 16]. Therefore, its use during adhesive procedures is still extremely controversial and should not yet be indicated for clinical use. The application of the Nd:YAG laser over the enamel, with simultaneous application of topical fluoride, has shown excellent results on the reduction of the hydroxyapatite solubility. This technique has been recommended for caries prevention [29].  

 

 

4.8.3

b

Safety Procedures

Due to the fact that it is a highly concentrated light, the effects of laser can be extremely deleterious when unintentional irradiation happens, as on the eye, for example. All the laser equipments are accompanied by specific glasses to filter the different wavelength emitted by each light. The safety glasses of the Nd:YAG device, for example, must not be used during the procedure with the Er:YAG or any other, because they are absolutely specific for each equipment (. Fig.  4.64). The room where the devices are used must have a sensor on the door, which automatically turn off the laser, in case any person comes in inadvertently [26]. The devices have security keys and some also have protected pedals, a way to guarantee that the beam is only emitted under the total control of the operator.  

..      Fig. 4.62  a Nd:YAG laser device PulseMaster 600 IQ (American ­Dental Technologies); b optical fiber to apply laser over the tooth structure

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a

b

c

d

4

..      Fig. 4.63  Tooth surface treated with Nd:YAG laser. a Aspect of the laser pulse over enamel; b greater magnification of the prepared enamel surface; c aspect of a laser pulse over dentin; d greater magnification of the prepared dentin surface

165 Instruments and Equipments

..      Fig. 4.64  Safety glasses for the use of high-power devices

Conclusion The development of dental instruments and equipments happened concomitantly with the development of materials and restorative/preventive concepts, following the technological advancements in dentistry. The operatory supply nowadays is composed of a wide range of instruments and equipments, with very specific design and clinical applicability. Dentists should get familiarized with such existing resources, in terms of characteristics, indication, and clinical applicability. This will enable practitioners to select a personal armamentarium that best suits the type of treatment offered and allow for best clinical practice.

References 1. Araujo RM, de Paula Eduardo C, Duarte Junior SLL, Araujo MAM, de Castro Monteiro Loffredo L. Microleakage and nanoleakage: influence of laser in cavity preparation and dentin pretreatment. J Clin Laser Med Surg. 2001;19:325–32. https://doi. org/10.1089/104454701753342785. 2. Bachmann L, Zezell DM.  Estrutura e Composição do Esmalte e Dentina – Tratamento Térmico e Irradiação Laser. 1st ed. Livraria da Fisica: São Paulo; 2005. 3. Balamuth L.  Ultrasonics and dentistry. Sound Its uses Control. 1963;2:15–9. https://doi.org/10.1121/1.2369595. 4. Baron A. L’Art Dentaire à Travers la Peinture. Paris: ACR Édition; 1986. 5. Baum L, Phillips RW.  Dentistica Operatória. Rio de Janeiro: Guanabara Koogan; 1996. 6. Black GV.  A work on operative dentistry. Chicago: Medico-Dental Publishing Company; 1908. 7. Boer NC.  Análise comparativa, clínica e histológica, do complexo dentina-polpa utilizando-se ponta CVD para ultrassom e ponta dia-

mantada para caneta de alta rotação em molares humanos. Vale do Paraiba University – UniVap. São José dos Campos; 2006. 8. Carone FM, Vieira DV. Comparação do tempo de trabalho no preparo cavitário entre as pontas CVDentus em Ultra-som e as pontas diamantadas em alta rotação. Técnicas Estéticas. 2007;4:42–6. 9. Corrêa AA. Dentistica Operatória. Artes Médicas: São Paulo; 1979. 10. Diniz MB, Gianotto RM, Cordeiro RC.  Remoção de tecido cariado com pontas CVD ultrassonicas como estratégia de manejo de criança. Rev Inst Cien Saude. 2008;26:263–6. 11. Genovese WJ. Laser de baixa intensidade. Aplicações Terapêuticas em Odontologia. Lovise Ltda: São Paulo; 2000. 12. Gonçalves SE, de Araujo MA, Damião AJ.  Dentin bond strength: influence of laser irradiation, acid etching, and hypermineralization. J Clin Laser Med Surg. 1999;17:77–85. 13. Gutknecht N, Eduardo CP. A Odontologia e o Laser. Quintessence: São Paulo; 2004. 14. Lima LM, Motisuki C, dos Santos-Pinto L, dos Santos-Pinto A, Corat EJ. Cutting characteristics of dental diamond burs made with CVD technology. Braz Oral Res. 2006;20:155–61. https://doi.org/10.1590/ S1806-83242006000200012. 15. Mastrantonio SS, Gondim JO, Josgrilberg EB, Cordeiro RCL. Minimizing fear during dental treatment using ultrasonic points. Rev Gauch Odontol. 2010;58:online. 16. Matos AB, Oliveira DC, Navarro RS, De Paula CE, Matson E. Nd:YAG laser influence on tensile bond strength of self-etching adhesive systems. J Clin Laser Med Surg. 2000;18:253–7. https://doi. org/10.1089/clm.2000.18.253. 17. Mesquita E, Kunert I. O Ultrassom na Prática Odontológica. Artmed: Porto Alegre; 2006. 18. Mondelli J, Ishikiriama A, Franco EB, Mondelli RL. Fundamentos de Dentística Operatória. 1st ed. Santos: São Paulo; 2006. 19. Mooney JB. Operatória Dental. Panamericana: Buenos Aires; 2006. 20. Morais ER. O medo do paciente ao Tratamento Odontológico. Rev Fac Odontol Porto Alegre. 2003;44:39–42. 21. Phillips RW.  Skinner’s science of dental materials. 8th ed. Rio de Janeiro: Interamericana; 1984. 22. Ring ME. Dentistry: an illustrated history. New York: Harry N Abrams Inc; 1998. 23. Roberson TM, Heymann H, Swift EJ. Sturdevant’s art and science of operative dentistry. London: Mosby/Elsevier; 2006. 24. Shintome LK, Umetsubo LS, Nagayasu MP, Jorge AL, Gonçalves SE, Torres CR. Avaliação clínica da laserterapia no tratamento da hipersensibilidade dentinária. Cien Odontol Br. 2007;10:26–33. 25. Summitt JB, Robbins JW, Hilton TJ, Schwarts RS.  Fundamentals of operative dentistry: a contemporary approach. 3th ed. Chicago: Quintessence; 2006. 26. Torres CRG, Borges AB, Kubo CH, Gonçalves SE, Araujo RM, Celaschi S, et al. Clareamento Dental com Fontes Híbridas LED/LASER. 2nd ed. São Paulo: Livraria Santos Editora Ltda; 2007. 27. Trava-Airoldi VJ, Corat E, Moro J. Studies of CVD diamond applications as ultrasound abrading devices in odontology and relates uses. Rev Bras Aplic Vácuo. 2006;25:15–9. 28. Vieira D.  Pontas de diamante CVD: Inicio do fim da alta-rotação? [Brazilian Ed]. J Am Dent Assoc. 2002;5:307–13. 29. Vlacic J, Meyers IA, Kim J, Walsh LJ.  Laser-activated fluoride treatment of enamel against an artificial caries challenge: comparison of five wavelengths. Aust Dent J. 2007;52:101–5. 30. Wigdor HA, Walsh JT, Featherstone JDB, Visuri SR, Fried D, Waldvogel JL. Lasers in dentistry. Lasers Surg Med. 1995;16:103–33. https:// doi.org/10.1002/lsm.1900160202.

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Nomenclature and Classification of Cavities and Tooth Preparations Carlos Rocha Gomes Torres and Ana Carolina Botta 5.1

Introduction – 168

5.2

Nomenclature – 168

5.2.1 5.2.2 5.2.3

 ental Planes – 168 D Basic Components of Tooth Preparations – 170 Nomenclature Rules for the Tooth Preparation Components – 172

5.3

Classification of Cavities and Tooth Preparations – 173

5.3.1 5.3.2

 lack’s Classification – 174 B Mount and Hume’s Classification – 177

References – 182

© Springer Nature Switzerland AG 2020 C. R. G. Torres (ed.), Modern Operative Dentistry, Textbooks in Contemporary Dentistry, https://doi.org/10.1007/978-3-030-31772-0_5

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Learning Objectives

5

The learning objectives of this chapter are to: 55 Define the nomenclature of tooth preparation 55 Identify the section and delimitation dental planes 55 Identify the walls and angles of tooth preparations 55 Present the nomenclature rules for the tooth preparation components 55 Describe the historical classification of lesions and tooth preparations based on the number of surfaces involved, anatomic location, extension, depth, and susceptibility of caries lesions and other defects

5.1

Introduction

Pathological processes that occur in the oral cavity can develop lesions on the tooth structure for various reasons: (1) carious lesions due to the caries process; (2) fractures due to traumas; (3) abfraction lesions due to occlusal overload associated with an unbalanced occlusion; (4) erosive tooth wear lesions due to the tooth contact with acidic substances that come from the diet or gastroesophageal reflux; and (5) abrasion lesions caused by the constant friction with hard substances over the teeth. These lesions may require surgical intervention due to loss of dental structure, tooth sensitivity, and the need of reestablishment of form, esthetics, and function. Despite the cause, before  the tooth structure to be restored and the data related to the procedures be registered and transmitted to other dentists, the location and the components of a tooth preparation must be easily identified through specific nomenclature. G.V. Black (1908) created a nomenclature system that can be used for all types of tooth preparations, allowing it to be easily identified by different observers [1]. Tooth preparations can be classified in different ways [3]. However, the most common classifications are still the ones created  by G.V.  Black (1908) [1] and modified by Simon (1956) [12] and Howard (1973) [5]. This chapter describes the nomenclature of lesions and tooth preparations and their historical classification based on the number of surfaces involved, anatomic location, extension, depth, and susceptibility to caries lesions and other defects.

to describe a caries lesion that promoted a distinct discontinuity or break of the tooth surface integrity. When the affected tooth was treated, the preparation of the remaining tooth structure was referred to as cavity preparation. Currently, as many indications for surgical treatment of teeth are not related to carious lesions, the preparation of the tooth should no longer be referred to as cavity preparation but as tooth preparation [2]. The tooth preparation is the result of a group of operative procedures that are necessary to remove carious tissue and produce adequate and compatible shapes to the remaining tooth structure and to receive a proper restorative material [3]. The objectives of tooth preparation are to (1) conserve as much healthy tooth structure as possible; (2) remove all defects while simultaneously providing protection of the pulp–dentin complex; (3) create a form on the tooth preparation so that, under the masticatory forces, the tooth or the restoration (or both) will not fracture and the restoration will not be displaced; and (4) allow the adequate placement of a restorative material [2]. Due to the shapeless aspect of the carious lesions and other lesions on the hard tissues, the explanations about nomenclature will be presented on tooth preparations, which have a more defined geometry. However, whenever possible, the same terms applied on the prepared cavities can be applied to describe the parts of the pathological cavities. 5.2.1

Dental Planes

In order to apply names to the components of tooth preparation, as well to the analysis of the inclinations of preparation walls, specific references called section and delimitation planes must be used [10]. Three section planes are used in the study of human anatomy (. Fig. 5.1). The anatomical plane that divides the body into right and left portions is called sagittal or median plane (longitudinal, anteroposterior), because it is a plane parallel to the sagittal suture. The frontal plane or coronal plane (vertical) divides the body into ventral and dorsal portions. The transverse or horizontal plane (lateral, horizontal) divides the body into cranial and caudal portions [4]. The sagittal plane is not ideal for analysis of each tooth separately due to the curvature of the dental arch (. Fig. 5.2). The sagittal and frontal planes would involve different surfaces from the incisors to the molars [3]. Only the horizontal plane would not have this variation. For this reason, in addition to the horizontal plane, two special vertical or axial section planes, named axiomesiodistal and axiobuccolingual planes, or just mesiodistal and buccolingual planes, are used. Those dental planes are parallel to the long axis of the teeth and extend in a mesiodistal or buccolingual direction, respectively. They also divide the tooth into mesial and distal halves or occlusal and cervical halves, respectively. In . Fig. 5.3, those planes are sectioning the central position of all tooth surfaces.  

 

5.2

Nomenclature

Nomenclature is a system of names or terms used in a particular science, discipline, or art, by which the professionals working on that area are able to understand each other. In order to have a good communication with colleagues and the dental team, it is very important to become familiar with the proper terminology of tooth preparations presented in this chapter. In the past, most restorative treatments were performed due to cavitated caries lesions, and the term cavity was used

 

169 Nomenclature and Classification of Cavities and Tooth Preparations

..      Fig. 5.3  Section planes for the tooth structure

..      Fig. 5.4  Delimitation planes ..      Fig. 5.1  Anatomic planes. F – frontal plane; H – horizontal plane; S – sagittal plane

tooth preparation) (. Fig.  5.4). The delimitation occlusal plane of a tooth is different from the occlusal plane of the dental arch, which is an imaginary plane extending from the incisal edge of the incisors along the cusp tips of the posterior teeth. Although not a real plane, the occlusal plane of the dental arch represents the mean of the occlusal surfaces curvature. In order to describe the location of a lesion and tooth preparation and its extension, the tooth surfaces can be divided into thirds (. Fig. 5.5) [1, 10]. The occlusal surface, on the mesiodistal direction, considering the buccolingual section plane, can be divided into mesial, middle, and distal thirds. On the buccolingual direction, considering the mesiodistal section plane, the occlusal surface can be divided into buccal, middle, and lingual thirds. The mesial, distal, lingual, and facial surfaces of a crown can be divided into thirds, both longitudinally and horizontally (. Fig. 5.5). In regard to the horizontal division, each axial surface of a crown can be divided into an occlusal (or incisal), middle, and cervical third. In regard to the longitudinal division, each facial or lingual surface may be divided into a mesial, middle, and distal third, while each mesial or distal axial surface may be divided into a lingual, middle, and facial/buccal third.  

 

..      Fig. 5.2  Difficulties of the use of the sagittal plane on the tooth nomenclature

Besides the section planes, delimitation planes tangent to the different tooth surfaces can be used for reference purposes. They are the mesial, distal, buccal/labial, lingual, gingival, and occlusal planes (commonly used as a reference during

 

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5.2.2

 asic Components of Tooth B Preparations

surface (. Fig. 5.6 – in yellow). The surrounding walls parallel to the long axis of the tooth are named vertical surrounding walls, while the ones perpendicular to the long axis of the tooth are named horizontal surrounding walls. The internal walls are the ones facing the pulpal chamber and do not extend to the external tooth surface (. Fig. 5.6 – in blue). The angles are the junction of two or more walls of the tooth preparations. Although the word angle leads the reader to imagine a “sharp edge,” in some preparations they can have a round configuration to reduce  stress concentration. Despite that, those junctions are still referred as angles for descriptive and communication purposes [11]. They can be of two types: line and point. A line angle results from the junction between two walls of different orientations along a line (. Fig. 5.7), while a point angle results from the junction of three walls of different orientations (. Fig. 5.8). The line angles can be subdivided in external and internal. The internal line angles are line angles whose apex points into the tooth. They can be divided into two sets. The first set includes the ones created by the junction of two external walls (. Fig. 5.7 red line – 1st S). The second set includes the ones created by the junction of the external and internal walls (. Fig. 5.7 – black line – 2nd S). An external line angle is a line angle whose apex points away from the tooth such as the ones formed by the junction between the internal walls (. Fig. 5.7d–f – blue line – E ). The nomenclature of the walls and angles is based on the tooth preparation as a cubic space, or the shape of a box. Although the tooth preparation can have an irregular shape, its wall and its angles are named as if they have a regular shape.  

Tooth preparations present two basic components: walls and angles [1]. The walls are the prepared (cut) surfaces of tooth preparations and can be divided into two types: external and internal. The external walls, also called surrounding walls, are the prepared surfaces that extend to the external tooth

5

 

 

 

 

 

 

..      Fig. 5.5  Division of the tooth surfaces in thirds

a

BUCCAL PULPAL

OCCLUSAL

b

c

AXIAL

LABIAL

LINGUAL MESIAL

AXIAL MESIAL

DISTAL

DISTAL

LINGUAL d

BUCCAL

GINGIVAL DISTAL

GINGIVAL

e

f

BUCCAL

PULPAL

BUCCAL

PULPAL

INCISAL

DISTAL AXIAL

LINGUAL AXIAL

BUCCAL AXIAL

GINGIVAL

GINGIVAL

AXIAL GINGIVAL

..      Fig. 5.6  Tooth preparation walls. The lines point to the names of the walls. a–f preparations on different teeth and tooth surfaces

LABIAL AXIAL GINGIVAL

5

171 Nomenclature and Classification of Cavities and Tooth Preparations

BP (2nd S)

a

b

MB (1st S)

DB (1st S)

OA (2nd S)

DO (1st S)

MO (1st S)

c

FL (1st S)

LA (2nd S)

MP (2nd S)

FA (2nd S)

LG (1st S) DP (2nd S) DL (1st S)

ML (1st S)

LP (2nd S)

DG (1st S)

st BP (2nd S) BD (1 S)

d

e

GA (2nd S)

IF (1st S) FA (2nd S)

DA (2nd S)

FG (1st S)

BA (2nd S)

LG (1st S)

AP (E)

IA (2nd S)

BP (2nd S)

LA (2nd S)

BG (1st S)

ID (1st S)

f

MA (2nd S)

AG (2nd S)

GA (2nd S)

MG (1st S)

DP (2nd S) BA (2nd S)

FG (1st S)

MA (2nd S)

DA (2nd S)

BG (1st S) AP (E) AG (2nd S)

MG (1st S)

AG (2nd S) DG (1st S)

AA (E)

AA (E)

..      Fig. 5.7  Line angles: (1st S) Internal first set – red lines; (2nd S) Internal second set – black lines; (E) External angles– blue lines. Their names correspond to the walls associated to them. a–f preparations on different teeth and tooth surfaces

a

MPB

b

c

FAL

DPB MPL

MAO

OAD

GAL

FAG

MAG

GAD DPL

DAI

BPD d

e

f

FAI

LAP

BAP

DAG MPA

MAG LAG

FAG

BPA BAG

BAG

AIA

AGA

APA AGA

..      Fig. 5.8  Point angles surrounded by circles. Their names correspond to the walls associated to them. a–f preparations on different teeth and tooth surfaces

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5.2.3

 omenclature Rules for the Tooth N Preparation Components

In order to simplify the understanding of the tooth preparation components nomenclature, G.V. Black proposed general rules [1, 3]: 55 1st rule – The cavity or tooth preparation receives the name of the surface or surfaces where it is located.

5

Following this rule, a tooth preparation only on the occlusal surface receives the name of occlusal or “O” preparation (. Fig. 5.6a). Preparation involving the mesial and occlusal surfaces is called mesio-occlusal preparation or “MO” (. Fig. 5.6d). Preparation involving the mesial, occlusal, and distal surfaces receives the name of mesio-occluso-distal preparation or “MOD.” Preparation involving the occlusal and lingual surfaces receives the name of occluso-lingual preparation or “OL,” and so on.  

 

..      Fig. 5.9  Sub-pulpal wall (arrow)

Tip

The description of the tooth preparation can be abbreviated by using the first capitalized letter of the tooth surface involved.

55 2nd rule – It is necessary to indicate the tooth where the cavity or the tooth preparation is located. Therefore, an occluso-distal preparation on the mandibular right first molar must be identified with an “OD” on tooth 46 (. Fig. 5.6d). A mesio-occluso-distal preparation on the mandibular right first molar must be identified as “MOD” on tooth 46. A mesio-occluso-disto-lingual preparation on the maxillary left first molar must be identified as “MODL” on tooth 26 (. Fig. 5.6e). 55 3rd rule – The external wall takes the name of the tooth surface that the wall is facing. 55 Following this thought, the wall that faces the buccal surface is called buccal wall. The wall facing the mesial surface is called mesial wall, and so on (. Fig. 5.6). 55 4th rule – The internal wall next to the pulpal chamber and parallel to the horizontal plane is called pulpal wall/ floor (. Fig. 5.6a, d, e). When the pulpal chamber is opened and the dental pulp removed, the wall that is parallel to the horizontal plane and corresponds to the floor of the pulpal chamber, receives the name of the sub-pulpal wall (. Fig. 5.9). 55 5th rule – The internal wall next to the pulpal chamber, but not parallel to the horizontal plane, is called axial wall. This type of wall occurs on the anterior teeth preparations and posterior teeth with the involvement of the smooth surfaces (. Fig. 5.6b–f).  

 

 

 

 

 

>> The axial wall is an internal wall that is oriented parallel to the long axis of the tooth. The pulpal wall is an internal wall that is oriented perpendicular to the long axis of the tooth and is located occlusally to the pulp. This internal wall may also be referred to as the pulpal floor [2].

55 6th rule – The line and point angles receive the names of the walls from which they are formed. Therefore, the junction of the buccal and gingival walls of preparation on posterior teeth with a proximal involvement is called bucco-gingival line angle or “BG” (. Fig. 5.7d). In this same preparation, the junction among the buccal, axial, and gingival walls is called bucco-axio-­gingival point angle or “BAG” (. Fig. 5.8d). The order to mention the wall that forms the angle is not important. The angles formed by the junction of the facial and lingual or facial, lingual, and axial walls, in preparations that involve the proximal surfaces of anterior teeth, can also be called the incisal line or incisal point angles, respectively (. Figs. 5.7c and 5.8c).  

 

 

>> The angles receive the names of the walls from which they are formed.

The angle formed by the junction among the buccal, axial, and gingival walls can be called BAG, GAB, ABG, and so on. 55 7th rule – The angle formed by the junction of the external surface of the tooth and a prepared wall is called cavosurface angle. The cavosurface angle may differ with the location on the tooth, the direction of the enamel rods on the prepared wall, or the type of restorative material to be used [2]. For better identification, it is convenient to specify the wall associated with the cavosurface angle. Therefore, the buccal, lingual, mesial, and distal cavosurface angles can be observed in . Fig. 5.10a, while in . Fig. 5.10b, the occlusal, gingival, mesial, and distal cavosurface angles are indicated. The terms preparation margin or cavosurface margin are also used to designate the junction of the tooth surface with the restorative material after it has been applied [5].  

 

173 Nomenclature and Classification of Cavities and Tooth Preparations

a

b

d

c

e

f

..      Fig. 5.10  Cavosurface angles are pointed. a–f preparations on different teeth and tooth surfaces

5.3

 lassification of Cavities and Tooth C Preparations

The word “classify” means to arrange in groups or categories that have similar characteristics. Many classifications of the cavities produced by the caries lesion have been proposed throughout history, according to its different aspects and treatments available. The simplest way to classify a cavity or a tooth preparation is according to the number of surfaces that are involved [7, 10]: 55 Simple cavities or preparations involve only one tooth surface. As an example, those placed exclusively on the occlusal, facial, lingual, or proximal surfaces (. Fig. 5.6a–c). 55 Compound cavities or preparations involve two tooth surfaces. As examples, the occluso buccal, mesio occlusal, mesiolingual preparations, etc. (. Fig. 5.6d, f). 55 Complex cavities or preparations involve more than two tooth surfaces (. Fig. 5.6e). The most common example is the MOD tooth preparation.  

 

 

Tooth preparation can also be classified according to its extension in the following types [7, 11]: 55 Intracoronal or inlay – preparation that is limited to the interior of the tooth structure, without the covering of any cusp. An inlay is usually “boxlike”, having internal and external walls (. Fig. 5.11). 55 Partial coverage extracoronal – can be of two types according to the number of cusps that are covered:  

55Onlay – preparation that covers one or more cusps of a tooth but not all of them (. Fig. 5.11b–d) 55Overlay – preparation that covers all cusps of a tooth but does not cover all smooth surfaces, with some parts of facial and/or lingual surfaces remaining preserved (. Fig. 5.11e) 55 Full coverage extracoronal or full crown – preparation that involves all the cusps and completely cover all the smooth surfaces of the teeth (. Fig. 5.11f).  

 

 

The preparations can also be classified according to the restorative plan in [7]: 55 Therapeutic preparations are the ones made with the aim to restore the tooth structure that was damaged by the caries disease, erosive tooth wear, abrasion, abfraction, or fractures. 55 Prosthetic preparations are the ones that are made in intact teeth, when it is necessary to make some indirect restoration that will support artificial teeth on an edentulous space. However, when they are made on partially destroyed teeth, they also have a therapeutic aim. Another way to classify the tooth cavities and preparations is in relation to its depth and proximity to the pulp, as presented on . Fig. 5.12a–f. The depth of the preparation is extremely important on the determination of the restorative technique to be used and on the protection that will be applied to the dentin-pulp complex. According to Mondelli [6], they can be classified in the following types:  

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a

b

c

d

e

f

5

..      Fig. 5.11  Classification of the tooth preparation according to their extension. a Inlay; b–d onlay; e overlay; f full crown

55 Shallow preparation – with the internal walls at the level before or slightly after the dentin-enamel junction (DEJ) (. Fig. 5.12b). 55 Medium preparation – with the internal walls from 0.5 to 1 mm beyond the DEJ (. Fig. 5.12c) 55 Deep preparation – with the internal walls beyond half the thickness of the dentin but still keeping more than 0.5 mm of remaining dentin between the wall and the pulpal chamber (. Fig. 5.12d). 55 Very deep preparation – the remaining tooth structure between the internal wall and the pulpal chamber is smaller than 0.5 mm, allowing the visualization, due transparency, of a pink discoloration in the internal wall because of the presence of the pulp underneath it. There is a great probability that small pulpal exposures that cannot be seen clinically exist (. Fig. 5.12e). 55 Pulpal exposure – an evident communication between the pulp and the tooth preparation (. Fig. 5.12f). Other classifications of the caries lesions are presented in other chapters of this book. The ICDAS classification is presented in the 7 Sect. 3.9 of 7 Chap. 3, while the radiografic lesion depth on 7 Chap. 16 (. Fig. 16.9).  

 

 

 

 

 

 

 

 

used  worldwide, which are the etiologic and the artificial. The etiologic classification grouped the cavities according to the susceptibility to caries lesions in specific tooth areas, due to the difficulty of good hygiene and the easy growth of bacterial biofilm. Based on this, the etiologic classification has two categories: 55 Pit and fissures – located in zones with greater susceptibility to develop caries lesions due to the accumulation of bacterial biofilm 55 Smooth surfaces – located in zones with relative immunity to caries lesions, due to self-cleaning effect provided by the contact with the soft tissues or the food bolus The artificial Black’s classification arranged the cavities into classes based on the tooth areas affected by the diseased and the associated type of treatment. Five classes were originally created [1]. Lately, Simon [12] included a new class to the original Black’s classification. 55 Class I – cavities and tooth preparations located on regions of pit and fissures of the posterior and anterior teeth, without the involvement of the proximal surfaces (. Fig. 5.13a–g). These include preparations on: 55Occlusal surface of premolars and molars (. Fig. 5.13a, b, g). 55Occlusal two-thirds of the buccal surface of the mandibular molars (. Fig. 5.13a, c).  

5.3.1

Black’s Classification

 

The two classifications of the cavities and tooth preparations proposed by G.V.  Black (1908) [1] are still the most

 

175 Nomenclature and Classification of Cavities and Tooth Preparations

a

b

c

d

e

f

..      Fig. 5.12  Classification of the tooth preparation, according to their depth. a Intact tooth; b shallow; c medium; d deep; e very deep; f pulp exposure – arrow

a

b

d

c

e

g

f

..      Fig. 5.13  a–f Class I caries lesion (arrows). g Occlusal erosive tooth wear lesion due to the abusive ingestion of acidic beverages

55Occlusal two-thirds of the lingual surfaces on maxillary molars including the lesions on Carabelli’s tubercle (. Fig. 5.13d). 55The lingual pit near to the cingulum on the lingual surface on the anterior maxillary teeth (. Fig. 5.13e). 55Sockwell [13] included in this class the cavities located on the incisal two-thirds of the labial surface of the anterior teeth (. Fig. 5.13f).  

 

 

55 Class II – cavities and tooth preparations that involve the proximal surfaces of the posterior teeth (. Fig. 5.14a–f). Even if the occlusal surface or any other tooth surface is involved simultaneously, the preparation is still named Class II. 55 Class III – cavities and tooth preparations placed on the proximal surfaces of the anterior teeth, without the involvement of the incisal edge (. Fig. 5.15a–d).  

 

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a

b

c

d

e

f

5

..      Fig. 5.14  a–f Class II caries lesions and tooth preparations (arrows)

a

b

c

d

..      Fig. 5.15  a–d Class III caries lesions and tooth preparation (arrows)

55 Class IV – cavities and tooth preparations that involve the proximal surfaces of the anterior teeth, with the loss of the incisal edge (. Fig. 5.16a–d). 55 Class V – cavities and tooth preparations located on the gingival third of the facial and lingual surfaces of all  

teeth, with the exception of the lingual surfaces of the anterior maxillary teeth, which are considered Class I (. Fig. 5.17a–d). 55 Class VI – cavities and tooth preparations located on the tip of the cusps and the incisal edges (. Fig. 5.18a–d).  

 

177 Nomenclature and Classification of Cavities and Tooth Preparations

a

b

c

d

..      Fig. 5.16  a–d Class IV caries and dental fracture lesions (arrows)

Black’s artificial classification revealed a chronological order, following the sequence of carious lesions development in individuals of different ages [3]. In young patients, the most common carious lesions are the Class I, followed by Class II cavities. In teenagers, Class II and Class III cavities are the most prevalent. The Class IV cavities may be a complication of the Class III due to trauma or progression of carious lesions. Finally, the Class V cavities are found, more frequently, in elderly patients [3]. Although being developed to describe the caries lesions, the Black’s classification has been also used to identify the preparations and restorations (e.g., a Class I amalgam preparation or a Class I amalgam restoration) [2]. 5.3.2

Mount and Hume’s Classification

Graham J.  Mount and W.  Rory Hume [9] proposed a new classification for cavities and preparations. Due to the modifications on the cutting instruments’ technology for tooth preparation, the development of adhesive restorative materials, and the current possibility of replacement of some restorative procedures by preventive measures, those authors concluded that Black’s classification failed by omitting the lesion extension, which is related to the decision about surgical and nonsurgical approaches [8].

This classification was based on two characteristics to describe the lesion on the tooth structure: site and size. This allows dentists to have a better understanding of the involvement of the tooth structure by the lesion and the selection of the most adequate treatment for each situation. This classification also simplifies the electronic data records and subsequently the communication among clinicians. According to the site, the lesions can be located on: 55 Site 1 – It describes all the lesions on located on pits and fissures of the occlusal surfaces of the posterior teeth, besides other defects on smooth surfaces of a tooth [9]. This includes grooves on the buccal surfaces of the mandibular molars, lingual groove on maxillary molars, grooves on cingulum, pits on anterior teeth and similar defects, as well as erosive tooth wear and abrasion lesion on the incisal edges of the anterior teeth and the occlusal surface of the posterior teeth (. Fig. 5.19a–f) [9].  

Tip

Site 1 includes all the lesions identified as Class I and VI according to Black’s classification.

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a

b

c

d

5

..      Fig. 5.17  a–d Class V caries and non-carious lesions (arrows)

55 Site 2 – It describes all lesions associated with the contact areas and placed below them, on the occlusal two-thirds of the tooth crown, both on anterior and posterior teeth (. Figs. 5.20a–g and 5.21a–g) [9].  

Tip

Site 2 includes all the lesions identified as Class II, III, and IV according to Black’s classification.

55 Site 3 – it describes all the lesions originated next to the gingival areas, on the cervical third of the crown or areas of exposed root, both on enamel, cement, or dentin, around the whole circumference of a tooth, including the proximal surfaces (. Fig. 5.22a–i).  

Tip

Site 3 includes the Class V according to Black and also lesions in root surfaces located on the mesial or distal surfaces, after gingival recession.

According to the size, the lesions can be classified as: 55 Size 0 (incipient) – It is a small and subsurface lesion, without cavitation, that can be remineralized or that has already remineralized, and there is only a residual stain [9]. No restoration is necessary for this size of lesion, and only preventative treatments are recommended. 55 Size 1 (minimum) – It is a lesion that progressed to the point of transition, where it cannot be exclusively treated with a preventative approach, and an operative intervention is indicated [9]. There is a small cavitation but with minimum involvement of dentin. 55 Size 2 (moderate) – It is a large lesion, but there is still sufficient sound tooth structure to maintain the integrity of the remaining crown and resist to the occlusal forces, without the need for additional changes on the tooth preparation, other than the removal of the carious tissue [9]. There is a moderate involvement of the dentin. 55 Size 3 (enlarged) – It is a more extended lesion. The remaining tooth structure is weakened to the extent that cusps or incisal edges are split or are likely to fail if left exposed to occlusal or incisal load [9]. The tooth preparation needs to be modified so that the restoration can be designed to provide support and protection to the remaining tooth structure [9].

179 Nomenclature and Classification of Cavities and Tooth Preparations

a

b

c

d

..      Fig. 5.18  a–d Class VI caries and attrition lesions (arrows)

55 Size 4 (extensive) – it is a lesion that has extensive loss of tooth structure such as a cusp of a posterior tooth or an incisal edge of an anterior tooth [9]. The application of this classification must include the use of both characteristics (site and size), as can be observed in . Table 5.1. In . Figs. 5.19, 5.20, 5.21, and 5.22, examples of this classification are shown, applied to clinical situations. If there are multiple lesions on the same tooth, each one of them must be reported separately.  

 

Example Examples of lesions description according to the Mount and Hume’s classification: 55 “Lesion 2.4 on the distal surface of the tooth 12” indicates that the lesion on the distal surface of the maxillary right

lateral incisor progressed in such a way that the incisal edge was lost. It suggests the need of a large esthetic restoration on this tooth. 55 “Lesion 2.1 on the mesial surface of the tooth 46” indicates that there is a small lesion on the mesial surface of the mandibular right first molar. It suggests the need of a minimally invasive tooth preparation. 55 “Lesion 2.2 on the OD surfaces of the tooth 36” indicates that there is a lesion of a moderate size, involving the occlusal and distal surfaces of the mandibular left first molar, with enough remaining tooth structure to resist to occlusal forces. 55 “Lesion 3.1 on the buccal surface and a lesion 2.2 on the MOD surfaces on the tooth 47” indicates that there are two distinct lesions on the mandibular right second molar. One small cervical lesion on the buccal surface and one moderate lesion involving the mesial, occlusal, and distal surfaces.

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b

a

c

5 d

e

f

..      Fig. 5.19  Use of the Mount and Hume’s classification at the site 1. a Size 0; b size 1; c size 2; d size 3; e, f size 4

a

e

b

c

f

d

g

..      Fig. 5.20  Use of the Mount and Hume’s classification at the site 2 on posterior teeth. a Size 0; b size 1; c size 2; d, e size 3; f, g size 4

181 Nomenclature and Classification of Cavities and Tooth Preparations

a

b

c

d

f

e

g

..      Fig. 5.21  Use of the Mount and Hume’s classification at the site 2 on anterior teeth. a Size 0; b, c size 1; d size 2; e size 3; f, g size 4

c

b

a

e

f

g

d

h

i

..      Fig. 5.22  Use of the Mount and Hume’s classification at the site 3. a Size 0; b size 1; c–f size 2; g, h size 3; i size 4

..      Table 5.1  Possibilities of application of the Mount and Hume’s classification Size Site

0

1

2

3

4

Incipient

Minimum

Moderate

Enlarged

Extensive

1 – Pit/fissure

1.0

1.1

1.2

1.3

1.4

2 – Contact areas

2.0

2.1

2.2

2.3

2.4

3 – Cervical area

3.0

3.1

3.2

3.3

3.4

5

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Conclusion

5

This chapter has addressed the nomenclature of lesions and tooth preparation and their classification. Dentistry has developed terminology useful in the communication of all aspects of tooth preparation, among dental students, professors, and clinicians. The nomenclature and classification of tooth preparations effectively describe preparation aspects with regard to complexity, anatomic location, three-­ dimensional orientation, geometry, and susceptibility of caries lesions and other defects. The classification of lesions is also important in regard to the patients’ treatment plan, influencing whether a restorative or preventative approach should be taken into consideration.

References 1. Black GV. A work on operative dentistry. London: Chicago Medico-­ Dental Publishing Company; 1908. 2. Boushell LW, Walter R. Fundamentals of tooth preparation. In: Ritter AV, Boushell LW, Walter R, editors. Sturdevant’s art and science of operative dentistry. 7th ed. St. Louis: Elsevier; 2019. p. 120–35.

. Corrêa AA. Dentística Operatória. Artes Médicas: São Paulo; 1979. 3 4. Dangelo JG, Fattini CA. Basic Dental anatomy. Rio de Janeiro: Atheneu; 1988. 5. Howard WW. Atlas of operative dentistry. 2nd ed. St. Louis: Mosby; 1973. 6. Mondelli J. Proteção do Complexo Dentinopulpar. São Paulo: Artes Médicas; 1998. 7. Mondelli J, Franco EB, Pereira JC, Ishikiriama A, Francischone CE, Mondelli RF, et  al. Dentística: Procedimentos Pré-Clínicos. 1st ed. São Paulo: Santos; 2002. p. 265. 8. Mount GJ, Hume WR.  A new cavity classification. Aust Dent J. 1998;43(3):153–9. 9. Mount GJ, Hume WR. A revised classification of carious lesions by site and size. Quintessence Int. 1997;28(5):301–3. 10. Ritacco AA. Operatória Dental: Cavidades Modernas. 2nd ed. Buenos Aires: Mundi; 1966. 11. Roberson T, Heymann H, Swift E.  Sturdevant’s art and science of operative dentistry. 5th ed. St Louis: Mosby; 2006. 12. Simon WJ.  Clinical operative dentistry. Philadelphia: Saunders; 1956. 13. Sockwell CL.  Silicate cement and self-curing acrylic resin restorations. In: Sturdevant CM, editor. The art and science of operative dentistry. New York: McGraw-Hill; 1968.

183

General Principles of Tooth Preparation and Carious Tissue Removal Carlos Rocha Gomes Torres and Falk Schwendicke 6.1

Introduction – 184

6.2

Biological Principles – 185

6.3

Mechanical Principles – 195

6.4

Prior to Tooth Preparation – 199

6.5

Steps of Tooth Preparation – 200

6.5.1 6.5.2 6.5.3 6.5.4 6.5.5 6.5.6 6.5.7

 utline Form – 200 O Resistance Form – 203 Retention Form – 210 Convenience Form – 213 Carious Tissue Removal – 215 Finishing of the Enamel Walls – 218 Cleaning of the Cavity – 218

References – 220

© Springer Nature Switzerland AG 2020 C. R. G. Torres (ed.), Modern Operative Dentistry, Textbooks in Contemporary Dentistry, https://doi.org/10.1007/978-3-030-31772-0_6

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Learning Objectives The learning objectives of this chapter are related to the following topics: 55 To understand the biological and mechanical principles of the tooth preparation 55 To explain the prior procedures of the tooth preparation 55 To learn about the steps of tooth preparation

6.1

6

Introduction

The main goal of tooth preparation and carious tissue removal was and remains the therapy of carious lesions. Traditionally, all carious lesions were managed invasively, i.e., using cutting or drilling action, and restoratively, i.e., with the placement of a restoration after the preparation and carious tissue removal. It is highly relevant to emphasize that, as discussed elsewhere in this book, current approaches for managing carious lesions focus on non-restorative measures and only employ invasive/ restorative means if not avoidable or due to aesthetic or functional reasons. Note that tooth preparation and carious tissue removal are further not strictly separated from each other, but rather interlink, and that for many modern materials, the preparation of a specific cavity shape during tooth preparation has lost some relevance given these materials being applied defect-oriented. Traditionally, however, and still applying to materials like amalgam (or ceramics or indirect metal restorations), the preparation was found to be the foundation for the superstructure, the restorative material; if the foundation fails, the superstructure will easily succumb to the stress that the tooth will undergo [1]. In a research performed by Healey and Philips, it was observed that 56% of the failure on the amalgam restorations that led to its replacement were due to incorrect tooth preparations, demonstrating the importance of this stage for the success of the restorative treatment [2]. On the other hand, it must be kept in mind that the tooth preparation is an irreversible surgical procedure, where mistakes damage tissues in an irreversible way [3]. Tooth preparation is defined as the biomechanical treatment of the carious lesion and other lesions on tooth hard tissues, in a way that the remaining tooth structure can receive a restoration that protects it, is resistant to the occlusal stress, and prevents the disease recurrence [4]. Note that tooth preparation performed for reasons other than caries, like erosive tooth wear, abrasion, abfraction, attrition  or other non-cariogenic hard tissue defects, will not include the carious tissue removal step [5].

Tooth preparation is defined as the biomechanical treatment of the carious lesion and other lesions on tooth hard tissues, in a way that the remaining tooth structure can receive a restoration that protects it, is resistant to the occlusal stress, and prevents the disease recurrence.

The main objectives of tooth preparation are (1) providing access to and allowing removal of the carious tissue, (2) providing clear margin (in a conservative way) where the restoration can end, and (3), for certain materials, providing a cavity shape so that under biting forces, the tooth and/or the restorations do not fracture and the restoration do not displace [5]. After the tooth preparation is ready, the restoration of the lost structure is performed, recovering the shape, function, and aesthetics of the tooth [4–6]. Therefore, it is the dentist’s responsibility to reconstruct the damaged tooth structure and complete its anatomy, reestablishing its function, allowing the patient to clean the restored surface while preserving the  sound remaining tooth structure and pulp vitality. Especially on the anterior teeth, the restoration must present an adequate color match with the remaining tooth structure, recovering the aesthetic. It is important to remember that the restorative procedure just repairs the damage caused by the carious disease and other problems; but this, by itself, does not eliminate the etiological factors that initially caused the lesion. To recover the patient’s health, an effective preventive program must be established, leading to a situation of low risk to develop new lesions [5]. Wherever possible, active lesions should be converted to inactive ones, helping the processes of defense and healing of the dentin and pulp. Before recommending an invasive treatment, noninvasive strategies should be considered, as every restoration has statistically only a limited lifetime. The decision to restore a tooth may begin a repetitive restorative cycle, where the restorations are changed several times during the life of the patient, and in each replacement, the cavity preparation gets bigger, resulting in an additional destruction of the tooth tissue, which may eventually lead to the extraction of the tooth. Every time that the dentist proposes the replacement of a restoration, the size of the preparation tends to increase, due to inadvertently cut of healthy tissue around the old restorations. In addition, as restoration fails oftentimes for different reasons (mainly secondary caries and fractures), that may also affect the remaining dental tissues [7]. >> The restorative procedure just repairs the damage caused by the carious disease and other problems; but this, by itself, does not eliminate the etiological factors that initially caused the lesion. >> Before recommending an invasive treatment, noninvasive strategies should be considered first, as every restoration has statistically only a limited lifetime. The decision to restore a tooth may begin a repetitive restorative cycle, where the restorations are changed several times during the life of the patient, and in each replacement, the cavity preparation gets bigger, resulting in an additional destruction of the tooth tissue, which may eventually lead to the extraction of the tooth.

185 General Principles of Tooth Preparation and Carious Tissue Removal

However, when a cavitation already exists, noninvasive measures will oftentimes not be able to arrest the lesion. The cavity needs to be filled by a restorative material, which is shaped to recover the tooth contour, allowing the control of the bacterial biofilm [7]. Other reasons to perform an invasive treatment are when the teeth show hypersensitivity to heat, cold, and sweet; when the attempts to arrest the lesion had failed; when some improvement on tooth function or aesthetics is needed; or when a dental displacement is probable to occur due to the loss of the interproximal or occlusal contact [7]. Restorations can be performed on three different ways, and they are the direct, the semi-direct, and the indirect techniques [8]. Using the direct technique, the restorative material is applied and shaped by the dentist directly into the tooth preparation in the patient’s mouth, creating the final restoration in one clinical session. Using the semi-direct technique, the restoration is also made in one clinical session, but the restoration is handled outside the mouth and then cemented into the tooth. The semi-direct technique can be intra- or extraoral. The intraoral technique consists in applying the restorative material directly into the tooth preparation, and, after curing, the restoration is removed, finished, and polished outside the mouth. After that, it is cemented into the tooth preparation. In the extraoral technique, an impression or scanning of the tooth preparation is performed. In the first case, an impression of the preparation with alginate is obtained, and a fast-setting material is used to prepare a model. Generally, a special die silicone material is used, which is applied inside the impression, creating a flexible model [9]. The restoration is made chairside by the dentist using composite resin and then cemented into the preparation. On the second case, the three-dimensional information of the preparation and surrounding teeth is transferred to a CAD/CAM system (computer-aided design and computer-aided manufacturing) using an intraoral scanner. Then, the restoration is prepared by the machine and cemented by the dentist. In the indirect technique, after the tooth preparation, an impression using a silicone material or an intraoral scanning is performed and a interim restoration is performed. Then a plaster or digital model is obtained and sent to a laboratory, where the laboratory technician will prepare a restoration (either using conventional techniques or digitally using CAD-CAM). After sending back to the dentist, it is cemented on the prepared tooth. The indirect technique requires two clinical sessions. >> Dental restorations can be performed on three different ways, which are the direct, the semi-direct, and the indirect techniques.

structures, but in perfect contact. Therefore, under bite stress, the adequate distribution of the force on the tooth-restoration interface is fundamental for the preservation of the remaining tooth structure and of the restoration itself. In this case, aspects like uniform depth of the preparation, specific shapes of the walls, and defined marginal configurations become important [5]. On the other side, the adhesive capacity that some restorative materials have modifies this scenario, because the forces applied over the remaining tooth structure are transmitted through the adhesive interface to the restorations, and vice versa, so that both behave similar to one, not two bodies, reducing the interference of the cavity shape. Therefore, the very precise requirements for the tooth preparation of nonadhesive restorations are reduced for adhesive ones. As described briefly above, the most common type of adhesive restoration, the resin composite ones, requires mainly the removal of the carious tissue, without the need to prepare uniform and specific cavity depth, designs for the walls, or marginal shapes. This simplification of the preparations is due to the physical characteristics of the composite and to the bond of the tooth structure [5]. Due to that, most of the adhesive restorations increase the fracture resistance of weakened teeth, which does not happen with conventional amalgam, for example [10]. The general principles of the tooth preparation can be divided into two groups, named biological and mechanical. Biological principles are related to the preservation and the protection of the tooth structure and periodontal tissue, whereas mechanical principles are related to the factors associated with stress distribution inside the remaining tooth structure and restorative material, transmitted through the tooth-restoration interface. 6.2

Biological Principles

The success of the clinical procedures requires a comprehension of the anatomic and biological nature of the tooth, with its components enamel, dentin, pulp, and cement, as well as supporting tissues. A clinical practice that violates the physical, chemical, and biological parameters of the dental tissues can lead to premature failure of the restorations, compromising the integrity of the crown, leading to secondary caries, discomfort to the patient, and eventually pulpal necrosis [3]. Enamel is composed mainly from hydroxyapatite crystals, with about 88% per volume, organized in a prismatic arrangement, creating a hard and strong structure that protects the vitalized dental tissues, namely, the dentin and the pulp. There are about 3000–4000 prisms (or rods) per mm2 of enamel (. Fig. 6.1a–d) [3]. Among the prisms, there is a mineralized structure called interprismatic enamel (or interrod) (. Fig.  6.1b). Even though most of the enamel is organized as prisms, a more external and smaller layer has crystals organized parallel to one another and perpendicular to the surface, called the prismless enamel (. Fig. 6.1d). The prisms run from the dentin-enamel junction (DEJ) to the external surface of the tooth (. Fig.  6.1a), and each  

An extremely important point when studying tooth preparations are the bonding properties presented by some restorative materials. Based on the bonding to the tooth structure, we can divide direct restorations in two types: adhesive and nonadhesive restorations. When a tooth is restored with a nonadhesive material, such as dental amalgam, the remaining tooth structure and the restorative material behave as two independent

 

 

 

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a

b

c

d

..      Fig. 6.1  a Photomicrography showing the longitudinal section of the enamel prisms “E” starting on the DEJ and following parallel to each other; b greater magnification showing the prisms core “P” and

the interprismatic enamel (red arrows); c cross section of the enamel prisms showing the prism core “P” and the interprismatic enamel (red arrows); d prismless enamel “PL” and prismatic enamel “P”

successive row drives through a slightly different path, following the pattern of a wave and a spiral course, producing a different arrangement for each group or layer of prisms. They change the direction horizontally and vertically, changing from clockwise to anticlockwise directions and vice versa, from the dentin to the external tooth surface [3, 11]. They initially follow a curved track through 1/3 of the thickness of the enamel next to the DEJ. Then, the prisms usually follow a

more direct track through the last 2/3 of the enamel to the surface. The borders of the enamel prisms form natural cleavage lines through which the longitudinal fractures can happen [3]. On the most external layer, where they are parallel, the enamel is more prone to fracture. This external enamel also has bigger prisms [12]. Groups of prisms of enamel can intertwine with other groups, creating the gnarled enamel, which happens next to the tip of the cusps and incisal edge.

187 General Principles of Tooth Preparation and Carious Tissue Removal

a

b

..      Fig. 6.2  a Presence of undermined enamel over an amalgam restoration (arrow); b fracture of the undermined enamel following the direction of the prisms after receiving a load on this region

The gnarled enamel is not prone to fractures like regular enamel, being as a result of functional adaptations of the enamel rods in areas of high loads. The enamel is as hard as steel, with a Knoop microhardness of 340, much higher than the dentin microhardness, which is around 70 [13]. A normal physiological contact between opposite teeth wears the enamel in a rate of 29 μm a year [14]. However, its effect on the vertical dimension can be compensated by the apical cementogenesis and passive tooth eruption [3]. Although the tooth enamel presents high microhardness, which gives it resistance to wear, it is also very brittle. When it is properly supported by dentin, this characteristic is not relevant in terms of fracture resistance. The dentin provides flexibility, and is capable to absorb the occlusal loads received by the enamel, preserving its integrity [15]. However, undermined enamel loses more than 85% of its resistance [15]. If a nonadhesive restorative material (such as the amalgam) is used under the undermined enamel, the load applied over the enamel will not be absorbed and dissipated by the material under it, and there is a great possibility of enamel fracture (. Fig. 6.2a, b).  

>> Although the tooth enamel presents high microhardness, which gives resistance to wear, it is also very brittle. When it is properly supported by dentin, this characteristic is not relevant in terms of fracture resistance. However, undermined enamel loses more than 85% of its strengths.

There are two possibilities to solve the problem related to the presence of undermined enamel. The first one is to remove it completely, even though this represents an increase of the final dimensions of the tooth preparation. The second possibility is to create artificial support to the enamel, providing its reinforcement, by using a restorative material that bonds to the tooth structure and simulate the mechanical behavior of the dentin [16]. For example, glass ionomer cements can

be used as dentin replacement (. Fig. 6.3a–c), or full composite resin restorations can be performed (. Fig. 6.3d). For nonadhesive restorations, cavity margins should hence follow, preferably, the same direction of the enamel prisms, avoiding that undermined prism remains. Otherwise, marginal degradation can occur, leading to deposition of bacterial biofilm and caries lesion development [15]. To reach this goal, the direction of the prisms on all the tooth surfaces must be known. In order to study the direction of the enamel prisms on the occlusal surfaces, the inner cusp inclines can be divided into three parts (. Fig. 6.4a). The prisms on the central third of the occlusal surfaces always lean toward the grooves in the direction of the center of the crown. The prism below the occlusal grooves is parallel to the long axis of the tooth, but the prisms in each side vary about 20° [17]. The greater the cusp angle, the greater the inclination of the prisms will be. On the medium third of the cusp inclines, the prisms trend to become perpendicular to the surface, whereas on the external thirds, that is, next to the cusp tip and marginal ridges, the prisms trend to lean to those tips. On the cusp tip, the prisms are almost parallel with the long axis of the tooth [15]. In the smooth surfaces, the prisms on the occlusal or incisal third lean toward the occlusal or incisal surface, around 24° in relation to a line perpendicular to the tangent plane on this region [3, 17]. On the medium third, they form a 90° angle with the tangent plane on this region, whereas on the gingival third, they lean around of 2° toward the cervical in relation to a line perpendicular to the tangents (. Fig. 6.4b) [15, 18]. In a circumferential analysis, the prisms around the tooth are perpendicular to the tangent plane (. Fig. 6.4c, d) [15]. In order to create enamel walls with the margins following the direction of the prisms, the whole direction of the cavity wall (CW) can be modified or only the enamel margins. This last procedure is called marginal trimming (. Fig. 6.50).  

 

 

 

 

 

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a

b

c

d

6

..      Fig. 6.3  Different ways to treat the undermined enamel. a Carious lesion with undermined enamel; b removal of the carious tissue preserving the undermined enamel (dotted line); c dentin “replace-

ment” using glass ionomer cement, followed by an amalgam restoration; d completely adhesive restoration using composite resin

As it has already been mentioned, the dentin is resilient, and it presents a good capacity to bear compression, due to its elasticity, and absorb the impact hitting the enamel, avoiding its fracture [3]. This is due to the presence of a high organic content, of about 30% by volume, mainly composed by type I collagen fibers, associated to 45% of inorganic ­material and 25% of water [3]. The dentin has many tubules running from the pulpal chamber to the DEJ. Encircling each tubule is the peritubular/intratubular dentin, formed mostly by minerals, while between them is the intertubular dentin, where the collagen fibers are located (. Fig. 6.5a–d). Another very important function of the dentin is to protect the pulpal tissue. Every time a preparation with a specific shape is prepared, as required for nonadhesive restorations, dentin tissue may be lost. To avoid dentin loss in deep areas of the cavity, base materials may be used. Instead of removing the healthy tooth structure to allow a uniform depth of the cavity, a base material can be used to level out the cavity floor (. Fig. 6.6a–d). The dentin can be classified in  three types, namely primary, secondary, and tertiary. The primary dentin is formed fast by the odontoblasts during the odontogenesis, until the end of the root formation. After this point, the dentin continues to form slowly, gradually reducing the internal volume of

the pulpal chamber; this one is called secondary dentin. Contiguously throughout the person’s life, peritubular dentin is constantly produced by the odontoblasts. As a result, the tubule lumen gradually becomes narrower. When external aggression occurs, it is detected by the pulp cells, and the formation of new dentin inside the pulpal chamber is increased, generating the so-called tertiary dentin. It can be classified in reactional or reparative. When low levels of irritative stimulus occur, such as the penetration of acids from a carious lesion through the tubules, that stimulate the odontoblasts to react and form more dentin on the region related to the affected tubules. Such tertiary dentin is called reactionary dentin. However, a high level of irritative stimulus or the pulpal exposure can destroy the odontoblastic layer. In that case, undifferentiated mesenchymal cells in the pulp will migrate to the area and differentiate to odontoblast-like cells, producing a kind of tertiary dentin named reparative dentin. In this case, the tubular organization is very different from that of primary or secondary dentin. The formation of tertiary dentin serves to protect the pulp from diffusion or penetration of bacteria and metabolic products. There is another kind of dentin named sclerotic (. Fig. 6.7a, b) [3]. Actually, the sclerotic dentin is the same primary or secondary dentin but with a greater mineraliza-

 

 

 

189 General Principles of Tooth Preparation and Carious Tissue Removal

a

b + 24 °

-2 °

c

d

..      Fig. 6.4  Direction of the prisms. a Longitudinal section of the crown on the buccolingual direction and the orientation and direction of the prism on each region; b direction of the prisms observed on the cervical third of smooth surfaces; c transverse cross section of the

crown showing the direction of the prisms in relation to the external surface; d prisms oriented on a perpendicular direction in relation to the external surface

tion. It is always associated with a carious lesion that stimulates the pulp reaction. The rate of peritubular dentin deposition increases, obliterating the tubules. Moreover, calcium and phosphate released from dentin hydroxyapatite, by the bacterial acids, reprecipitate deeply inside the tubules below the lesion, filling them up [19, 20]. The preservation of sclerotic dentin is the best way to protect the pulp. It should never be removed, although has a darkened color, ranging from brown to black. It is very hard on probing, as it contains a greater amount of minerals and radiographically appears as a radiopaque region (. Fig. 6.7b). The sclerosis is a predictable response that protects the dentin tubules in more than 95% of the teeth with caries lesions [3].

Another important aspect to be considered during tooth preparation is to avoid the heating of the tooth structure. The friction of the cutting or abrasion instruments, when they are not cooled properly, can lead to very high temperatures. This heat is easily transmitted to the pulp, causing injuries. Zack and Cohen reported that the continuous contact of a dental bur on a tooth for 25 s, without cooling, can produce an increase of the pulp temperature up to 6 °C above the normal [21]. Another study from the same authors showed that a temperature increasing of 5.5 °C above the normal situation can lead to irreversible damage of the pulpal tissue in 15% of the cases. They also showed that a temperature increasing of 11 °C will result in pulp necrosis in 60% of the cases [22]. The heating can not only occur during tooth preparation but also during polishing of restorations at high speed or with excessive pressure [23–25]. To avoid such problems, the high-speed handpieces must only be used with a strong spray of air-water, and the contact between instrument and tooth should not be continuous but intermittent [5, 26]. In cavities with a box shape, the use of high-speed handpieces with only one

 

Tip

The preservation of sclerotic dentin is the best way to protect the pulp. It should never be removed, although has a darkened color, ranging from brown to black. It is very hard on probing, as it contains a greater amount of minerals and radiographically appears as a radiopaque region.

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a

b

c

d

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..      Fig. 6.5  Dentin tubules. a, b Cross section; c, d longitudinal section (I, intertubular dentin; P, peritubular dentin)

water outlet may not allow sufficient cooling of the active head of the rotary instrument, because the water jet will hit the external surface of the tooth and not enter the cavity (. Fig. 6.8a). Therefore, handpieces with several air-water spray outlets are required, avoiding the occurrence of blind spots (. Fig.  6.8b). Moreover, sharp burs or diamonds should always be used, increasing their cutting or abrasion efficiency and reducing the heating generation. In addition, restorative material with small exothermal curing reactions and low heating light-­ curing units should be employed [27].  

Tip

Handpieces with several air-water spray outlets are required, avoiding the occurrence of blind spots with insufficient cooling of the active head of the bur.

 

It is also important to avoid excessive drying of the dentin with air blows [27]. As can be observed in . Fig. 6.9a–c, the dentin has several tubules, which have direct contact with the pulp. Due to the presence of interstitial fluid in the pulp, the tubules  

191 General Principles of Tooth Preparation and Carious Tissue Removal

a

b

c

d

..      Fig. 6.6  Creating a flat pulpal wall through the application of a base material. a Pulpal wall with remaining carious tissue on the central region; b removal of the carious remaining tissue with a round

a

bur; c prepared cavity with an irregular pulpal wall; d filling of the irregular area with GIC (arrow)

b

..      Fig. 6.7  Sclerotic dentin. a Clinical aspect of the darkened dentin on the pulpal wall; b radiography of the same clinical case showing the radiopaque aspect at the floor of the cavity (arrow)

are constantly filled by the so-called dentinal fluid. A pulpal pressure of about 11 mmHg creates a flux of this fluid toward the outer dentin surface [28]. A very intense drying causes the evaporation of the fluid inside the tubules, and, by capillarity,

a suction force is created, which aspirate the odontoblasts killing the cells. That results in postoperative sensitivity, forcing the pulp to promote the recovery of the odontoblastic layer by mesenchymal stem cell differentiation (. Fig. 6.9a–c).  

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a

b

6 ..      Fig. 6.8  a High-speed handpiece with only one water outlet, resulting in “blind” spots without irrigation (arrow); b handpiece with several air-water sprays in different directions, producing an adequate cooling

following chapters (. Fig. 10.13r–t), or using specific guards for this purpose, as it can be observed on . Fig. 6.10a, manufactured in very strong stainless steel. There is an interproximal guard that already comes with a wedge attached to it, protecting at the same time the adjacent tooth and the gingival tissue (WedgeGuard®-Triodent) (. Fig. 6.10b). The metallic strip can be removed, and the wedge be then used during the restoration step. It is also very important to consider the thickness of the enamel and the dentin and their relation to the volume of the pulpal chamber in each region of the tooth. In . Figs. 6.11a–o and 6.12a–o, there are pictures of the same teeth obtained from the intact structure, after complete demineralization to exhibit the dentin and after further clearing to show the pulpal chamber. It is possible to analyze different tooth groups in facial, mesial, and incisal/occlusal view. It can be observed that the enamel covers the entire anatomic crown of the teeth with various  thicknesses in different areas. Enamel is thicker on the occlusal and incisal areas and becomes progressively thinner on the axial surfaces toward the cementoenamel junction (CEJ), with a thickness of 0.2 mm on cervical areas. The thickness also varies from one type of tooth to another, with an average of 2 mm on the incisal edges, ranging from 2.3 to 2.5 mm on the premolar’s cusp tips and 2.5–3 mm on the molar’s cusp tips. Generally, on the occlusal surface of posterior teeth, the thickness is reduced toward the junction of the developmental lobes. On the internal third of the occlusal cusp inclines, the thickness varies from 0.2 to 0.5 mm and sometimes zero when there is a fissure in the junction of the lobes. The lingual layers of the enamel generally are thinner than the facial ones. With the aging, the enamel thickness on the occlusal surfaces decreases due to the abrasion promoted by of the food bolus or attrition with the opposite tooth, while the mineral content increases making it more brittle. The dentin thickness changes throughout the life, due to the constant deposition of secondary dentin and, in some  

 

 

 

..      Fig. 6.9  Aspiration of the odontoblastic process because of the excessive drying of the dentin. a Cell in the normal position; b dentin fluid being removed due to excessive drying producing the cell aspiration; c odontoblasts completely aspirated inside the tubule

Tip

The excessive drying of the dentin with air blows can result in odontoblastic layer death and must be avoided.

Besides avoiding damage to the tooth that will be restored, tooth preparation procedure should also not cause damage to the adjacent tooth. Unfortunately, iatrogenic cutting of intact adjacent surfaces is frequent. A study showed that during the approximal box preparation, without protection of the neighboring tooth, iatrogenic damage can happen in up to 100% of the adjacent surfaces, even if the procedure is performed carefully [29]. The slight contact of a bur or a diamond point over those surfaces can cause an immediate damage that the bacteria would take years to create. Therefore, those regions should be protected with interproximal guards, either by the use of a steel matrix band, as it will be described on the

193 General Principles of Tooth Preparation and Carious Tissue Removal

a

b

..      Fig. 6.10  Interproximal guards. a InterGuard® (Ultradent); b Wedgeguard® (Triodent)

a

b

c

d

e

f

g

h

i

..      Fig. 6.11  Crowns of maxillary teeth in a facial, mesial, and occlusal/incisal view, showing the thickness of the enamel and the volume of the pulpal chamber. a–c Central incisor; d–f lateral incisor; g–i canine. j–l premolar; m–o molar

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j

k

l

m

n

o

..      Fig. 6.11 (continued)

situations, also tertiary dentin, reducing the volume of the pulpal chamber (. Fig. 6.13a, b). It is known that the secondary dentin is deposited preferably on the pulpal horns and on the pulpal chamber roof and floor, causing that, after many decades, it becomes very narrow on the occlusogingival direction [30]. Therefore, the tooth preparation on the teeth of a young patient presents a significantly greater chance of pulpal exposure than on those of a patient with more advance age.  

>> The tooth preparation on teeth of a young patient presents a significantly greater chance of pulpal exposure than on those of a patient with more advance age.

It is known that the shape of the pulpal chamber follows the morphology of the tooth cusps. Therefore, when a preparation is performed to create a flat pulpal wall, not following the external contour of the crown, there will be areas where pulpal tissue is closer to the wall, resulting in a greater risk of accidental exposure. On the mandibular first premolars, for example, there is a very large discrepancy of the cusp volume, resulting in a buccal pulp horn much larger than the lingual one. Therefore, as will be presented on further chapters, the classic shape of a cavity for silver amalgam is modified, making the pulpal wall parallel to a plane that tangents both cusps, instead of being perpendicular to the long axis of the tooth, in order to avoid the accidental exposure of the pulpal tissue (. Fig. 6.14a, b). Another very important biological aspect is related to the physiological principle of biologic width, which is a natural seal that develops around the tooth and protect the internal medium from bacterial penetration [4]. Its preservation or  

recovery is paramount to the periodontal health. The biologic width is the natural distance between the bottom of the gingival sulcus and the top of the alveolar bone crest, including the juntional epithelium and connective tissue attachments (. Fig. 6.15) [31]. In the past, it was proposed to place the cavity margins inside the gingival sulcus, because this region was considered an area of relative immunity to the caries. However, nowadays, it is known that the restoration interface will almost never be perfect and interfacial defects and gaps will certainly exist in some regions. Those areas are susceptible to biofilm deposition, resulting in aggression to the surrounding gingival tissue [5]. The margins of the restorations placed more than 1 mm inside the sulcus, invading the biologic width, may be related to the inflammation, bleeding, hyperplasia, and gingival recession. Therefore, the preparation margins should, whenever possible, be placed above the gingival margin [3, 4]. However, when restorations are placed in aesthetically relevant areas, such as the maxillary anterior region, the preparation margin needs sometimes to be placed a little inside the sulcus, to hide the tooth-restoration interface, but never invading the biologic width [3, 4]. With highly aesthetic materials (like composites or ceramics), this is, however, usually not needed any longer.  

The biologic width is the natural distance between the bottom of the gingival sulcus and the top of the alveolar bone crest, including the junctional epithelial and connective tissue attachments.

195 General Principles of Tooth Preparation and Carious Tissue Removal

It is also important to avoid damage to the gingival tissue, with cutting instruments, during the preparation procedure. For that, wooden wedges can be inserted into the interproximal space before the preparation of the proximal boxes (. Fig. 10.13e). This way, any unexpected contact of the cutting instrument will happen on the wedge, and not on the gingiva [5]. There are also some specific instruments for displacement and protection of the gingival tissue during the tooth preparation, as shown in . Fig. 6.16.  

 

6.3

Mechanical Principles

The external forces applied onto both the restoration and the remaining tooth structure produce internal stress inside the restorative material and tooth, being transmitted through the interface. As it has been mentioned before, for the nonadhe-

sive restorations, the restorative material and the remaining tooth structure behave as independent structures in intimate contact, which can result in some circumstances in fracture of the tooth and displacement of the restoration. The mechanical principles of the tooth preparation have the objective to avoid that such phenomenon to happen, increasing the longevity of the restorations. Therefore, it is important to analyze the adhesive capacity of the restorative material, its physical properties, and the final characteristics of the tooth preparation. The restorations undergo a combination of forces, both in axial, oblique, and transversal direction [32]. An intact mandibular molar requires an axial force of about 300 kg to fracture [32]. However, the maximum biting force reported on the literature was 81.6 kg [33]. The main question is what is the resistance of the restored tooth, weakened by the destruction of its natural structure. According to Corrêa [6], even

a

b

c

d

e

f

g

h

i

..      Fig. 6.12  Crowns of mandibular teeth in a facial, mesial, and occlusal/incisal view showing the thickness of the enamel and the volume of the pulpal chamber. a–c Central incisor; d–f lateral incisor; g–i canine. j–l premolar; m–o molar

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j

k

l

m

n

o

..      Fig. 6.12 (continued)

a

b

..      Fig. 6.13  a Pulpal chamber of the tooth of a young patient (arrow – pulp horn); b pulpal chamber of the tooth of an elderly patient with a worn occlusal surface and reduced volume of the pulpal chamber

though it was possible to perform precise mathematical calculation and to determine exactly the intensity of the forces that the restorations and tooth preparations undergo under mastication, the clinical reality does not allow such precision. Instead of building absolute numbers, hence, knowledge about mechanical principles of tooth preparation and restoration should be applied. The forces necessary for mastication are produced by the muscles and are transmitted to the teeth through the alveolar bone and periodontal ligaments. The response of the tooth is determined not only by the magnitude of the forces but also by the nature and position of the contact surfaces. When certain forces hit inclined planes, such as those created by contacts among the smooth and masticatory cuspal inclines of a

mandibular premolar with the masticatory cuspal inclines of a maxillary premolar, they are decomposed, resulting in horizontal components, producing so-called wedge effect. It can lead to the displacement or fracture of either the remaining tooth structure or the restoration, depending on which offers lesser resistance (. Fig. 6.17) [6]. It is possible sometimes  to see the consequences of the  wedge effect in large MOD nonadhesive metallic restorations. When they receive occlusal loads, the forces are partially transmitted to the surrounding walls, pushing them and producing cuspal deflection, sometimes resulting in oblique crack propagation from the internal line angles toward the cervical area and cusp fractures (. Fig. 6.18a, b) [4, 34].  

 

197 General Principles of Tooth Preparation and Carious Tissue Removal

a

b

..      Fig. 6.14  Modification of the cavity shape due to the tooth anatomy of the first mandibular premolars. a Pulp wall parallel to the horizontal plane, with the consequent exposure of the pulp and

excessive cutting of the buccal cusp (arrows); b pulpal wall parallel to the plane that tangents the top of the cusps, avoiding pulp exposure

GINGIVAL SULCUS JUNCTIONAL EPITHELIUM

CONNECTIVE TISSUE ATTACHMENT

..      Fig. 6.16  Protection of the gingiva during the tooth preparation

..      Fig. 6.15  Biologic width (junctional epithelium + connective tissue attachment). Image kindly provided by Dr. Miguel Angel Castilho Salgado, professor of Histology at the Institute of Science and Technology of São José dos Campos – UNESP – Brazil

When the teeth are prepared and the reinforcing structures such as marginal and oblique ridge are removed, the cusp elongation phenomenon occurs [35–37], resulting in even greater cuspal deflection. On intact teeth the cusps have a mechanic height equal to the anatomic height, measured from the cusp tip to the bottom of the central groove (. Fig.  6.19a). When a MOD preparation is created, the mechanical height of the cusp increases, since it has now the distance between the tip of the cusp and the gingival wall of the preparation (. Fig. 6.19b) [34]. The larger and deeper the cavity, the larger is the mechanical height. According to Mondelli [4], such elongation can lead to disastrous effects if the restoration is not planned to compensate this mechanical  

 

..      Fig. 6.17  Wedge effect on an intact tooth

effect, for example, by providing an adhesive restoration or by covering the cusps when the nonadhesive restoration is performed. Strain is the response of a system to an applied stress. When a material is loaded with a force, it produces a stress,

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a

b

6 ..      Fig. 6.18  a Wedge effect on a restored tooth. The compressive load (vertical arrow) produces tensile stress (horizontal arrows) toward the cavity walls; b oblique fracture of a cusp, starting on the sharp line angle

a

b

..      Fig. 6.19  Phenomenon of the elongated cusps. a The anatomic and mechanic heights of the cusps are equal on intact tooth; b the mechanic height in a prepared tooth is higher, increasing the cuspal deflection

which then causes a material to deform. In  engineering the  strain is defined as the amount of deformation in the direction of the applied force divided by the initial length of the material. The tooth structures and the restorations undergo a combination of forces, both axial (compression and tensile) and oblique or transversal [38]. When a material is loaded with a force, it produces internal stress that causes a deformation on the material. The stress is defined as the force per unit area of a material. According to the direction of the load, the stress can be compressive, tensile, or shearing (. Fig.  6.20a–c). If the force is of compression nature, as a result of the occlusal contact with an antagonist tooth or food, compressive stress will occur in the interior of the material, and the strain will result in the shortening of the structure (. Fig. 6.20a) [33]. If tensile load is applied, such as when chewing sticky food, the tensile stress will occur and result in the elongation of the body (. Fig.  6.20b). A very sticky food can generate tensile forces from 5 to 10 kg [38]. If one end of the structure  

 

 

is fixed, as a cantilever beam, and it receives a lateral load on the free end, known as shear load, one side of the beam will show tensile and the other compressive stress (. Fig. 6.20c). This type of stress happens, for example, when the cusp elongated after deep tooth preparation contact the antagonist tooth, or when the lingual surface of maxillary incisors contacts the incisal edge of mandibular incisor [6, 39]. The deformation of the structure can be elastic, which is reversible and will disappear when the load is removed, or plastic, when it is permanent. Each restorative material, as well as the enamel and dentin, has a certain capacity to undergo elastic deformation under occlusal loads, maintaining its original shape. However, when an inadequate restorative material is used, or the capacity of elastic deformation is exceeded, a fracture of the restorative material or of the tooth structure will occur. Other aspect to be analyzed is that materials, subjected to repeated loading above a certain threshold, will suffer fatigue and microscopic cracks will occur at locations of stress con 

199 General Principles of Tooth Preparation and Carious Tissue Removal

centration. Those can propagate suddenly causing catastrophic failure. Fatigue can be defined as the weakening of the materials by damage accumulation, at a specific region, caused by repeatedly applied loads. In this situation, the

material may fracture after receiving a load much smaller than the normal nominal material strength. All occlusal contact in new restorations should be properly adjusted to reduce the cyclic stress, increasing their longevity [6, 39].

a

Fatigue can be defined as the weakening of the materials by damage accumulation, at a specific region, caused by repeatedly applied loads.

-h h

Tip

b

The occlusal contacts in new restorations should be properly adjusted to reduce the cyclic stress and fatigue of the material and remaining tooth structure, increasing their longevity. +h

6.4

h

c

d

Prior to Tooth Preparation

Before starting the tooth preparation, a series of aspects should be considered to guarantee that the best strategies of preparation and restoration are chosen. The adjacent tooth’s position should be considered. If migration of the affected tooth has occurred, or the proximal surface of the adjacent tooth has invaded the interproximal space, restoring the proximal contour without compromising the space for the interdental gingival papilla can be impossible (. Fig. 6.21a, b). In this case, the recovery of the space, through orthodontic movement, must be performed before the final restoration is performed. Initially, a temporary restoration of the cavity needs to be performed, and then, orthodontic appliances or  – much simpler  – an orthodontic elastic separator (rubber ring) is placed. That can be repeated until a total recovery of the space is reached, allowing an anatomically corrected final restoration to be performed.  

..      Fig. 6.20  Deformation of the materials under external the forces. a Compression; b tensile; c shear. The red arrows show the direction of the loads, while the green arrows show the direction of the stress. h means the height of the bar; −h shows a negative strain; +h shows a positive strain; d shows strain under shear forces

a

b

..      Fig. 6.21  a, b Mesialization of the adjacent tooth and the invasion of carious lesion cavity

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a

b

6 ..      Fig. 6.22  Importance of the radiographic analysis on the planning of the preparation. a Lesion of medium depth, with a good amount of intact dentin above to the pulp chamber (arrow); b deep lesion with a

great risk of pulpal exposure during the removal of the carious tissue (arrow)

In relation to the occusion of the  antagonist tooth, it is important that the contacts on the maximum intercuspation (MIC) or centric occlusion (CO) are verified. For that, a thin sheet of articulating paper, preferably > The contemporaneous approach is to remove the minimum quantity of tooth tissue, only enough to adequate the preparation to receive the restorative material.

When preparing the outline form, the dentist should evaluate the extension of the lesion and the consequent weakening of the cusp. If a nonadhesive restoration is planned, cusp covering should be considered, i.e., covering the cusps with a restorative material. To decide about cusp coverage, the distance between the central groove and the top of the cusp should be evaluated (. Fig. 6.25a) [5]. If the extension is less than 2/3 of the distance, the cusp covering is not necessary. On the other side, if the extension is greater than 2/3, it should be considered (again, mainly if using nonadhesive materials) (. Fig.  6.25b) [5]. The cusp covering of a weakened teeth with large preparations can increase the fracture resistance considerably [4]. If a fracture happens, it will occur in the restorative material, not the tooth, and the treatment will be reparable. If an adhesive material is used, however, this may allow increasing the fracture resistance even without cusp coverage [5].  

 

b

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a

b

6 c

..      Fig. 6.24  Variations of the outline of a Class I preparation for silver amalgam. a Involving all the grooves (classic preparation); b involving only the central groove; c restricted to the pits. The outline must be the

a

most conservative possible, restricted to the caries-­affected grooves, for the maximum preservation of intact tooth structure

b

..      Fig. 6.25  a Analysis of the lesion extension and the weakening of the cusp by evaluating the remaining tooth structure. The distance between the central groove and the cup tip is divided in three thirds. b Restoration with cusp covering

The outline form varies according to the anatomic shape of each tooth. As it extends over the pits and fissures on the occlusal surface, the margins usually do not take a straight line from one point to another, but they follow a soft line that preserves sound tissue [5]. An abrupt change in the outline form may increase the risk of fracture, especially if amalgam is used as restorative material. The angle formed by the junc-

tions between the surrounding walls of a preparation (first set of internal line angles) must also be rounded to improve the adaptation of the restorative material and decrease the concentration of stress. In addition, such rounding often allows to remove undermined enamel [15]. Sometimes, a pit or groove is extremely deep and allows retention of bacterial biofilm, and it is not favorable to have

203 General Principles of Tooth Preparation and Carious Tissue Removal

the interface of an amalgam restoration on this area. On the classic technique using the extension for prevention principle, all the grooves would be included on the preparation, resulting in cutting of healthy tooth structure. Alternative, wearing and smoothing the enamel, thereby removing the retentive groove, has been proposed. This procedure of minimal changing the enamel shape with rotary cutting instruments is known as enameloplasty, avoiding extending the outline form of the preparation [5]. However, it also involves removal of sound tissue. In most cases, then, sealing such areas can be a valid option. Generally, when using adhesive materials, such considerations play a lesser role. As it has already been mentioned, the contact with the antagonistic tooth should not happen exactly in the region of the interface tooth-restoration. If this happens, the outline of the preparation should be modified to include this region, reducing the chances of marginal fractures (. Fig. 6.26a, b) [15, 44]. Reinforcing structures, such as the oblique and marginal ridges, should be preserved  wherever possible. However, when there is a plan to make a nonadhesive restoration, it is important that the remaining ridge structures have at least 1 mm thickness [4]. If it is too fragile, e.g., > Caries is no longer understood as an infectious disease, but rather as an ecological imbalance within the biofilm, which is shifted toward acidogenic and aciduric bacteria, mainly facilitated by a frequent intake of carbohydrates.

Consequently, the management of a carious lesion does no longer mainly rely on removal of the “infected” diseased tissue and the placement of a restoration. Instead, restricting

carbohydrate intake and controlling the presence of a biofilm via oral hygiene are emphasized. However, removing biofilms will no longer be possible if a carious lesion is not cleanable with a toothbrush, i.e., the lesion is cavitated, with overhanging enamel/dentin preventing the toothbrush from accessing it. Hence, for such cavitated lesions, carious tissue removal, cavity preparation (as described), and restoration oftentimes remain needed. The question now, however, is: How much carious tissue do we need to remove after having prepared the cavity and before placing the restoration? >> Biofilms removal is not possible in cavitated carious lesion, and carious tissue removal (cavity preparation) and restoration remain needed.

Previously the aims of carious tissue removal were to remove all bacterially contaminated and demineralized tissue, without any discrimination about different qualities of carious tissue (hardness, moisture, color). This was carried out

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regardless of the consequences, and it was considered better to remove it all, even at the expense of the dental pulp, with high risks of pulp exposure, especially if performed in deeper lesions (extending close to the pulp). Today, the main question is, instead: “How can we achieve the best longevity for the tooth?” To answer this question, a number of guiding principles were agreed on [64, 65]: 55 Preserve non-demineralized and remineralizable tissue. 55 Achieve an adequate seal by placing the peripheral restoration onto sound dentin and/or enamel, thus controlling the lesion and inactivating remaining bacteria. 55 Avoid discomfort/pain and dental anxiety. 55 Maintain pulpal health by preserving residual dentin (avoiding unnecessary pulpal irritation/insult) and preventing pulp exposure. 55 Maximize longevity of the restoration by removing enough soft dentin to place a durable restoration of sufficient bulk and resilience [65].

Hence, the following terms have been agreed on to describe the dentin which is left or removed [64]: 55 Soft dentin: “Soft dentin will deform when a hard instrument is pressed onto it, and can be easily scooped up (e.g. with a sharp hand excavator) with little force being required.” 55 Leathery dentin: “Although the dentin does not deform when an instrument is pressed onto it, leathery dentin can still be easily lifted without much force being required. The hardness of leathery dentin is between that of soft and firm dentin.” 55 Firm dentin: “Firm dentin is physically resistant to hand excavation and some pressure needs to be exerted through an instrument to lift it.” 55 Hard dentin: “A pushing force needs to be used with a hard instrument to engage the dentin and only a sharp cutting edge or a bur will lift it. A scratchy sound or ‘cri dentinaire’ can be heard when a straight probe is taken across the dentin.”

Of course, avoiding pulpal exposure is relevant mainly in deep lesions, in teeth with vital painless pulps, as any kind of exposure will be managed using endodontic means, which either have a poor prognosis (like direct capping) or are highly invasive and oftentimes shorten the lifetime prognosis of the tooth (like root-canal treatment) [66–68]. On the other hand, leaving carious dentin beneath restorations means leaving softer, bacterially contaminated, demineralized dentin below this restoration. The lower elastic modulus of such dentin and the reduced bond capabilities compared with sound dentin have been found, to varying degree, to affect the stability of the restoration [69– 71]. It is likely that this is relevant when very large amounts of carious dentin left under a restoration are left, while small areas of soft dentin being left to not expose the pulp will have only limited impact [72–74]. When there is no risk of pulp exposure, however, there is no argument against removing carious dentin in a way which will maximize restoration longevity. If these general principles are to be employed, dentists need to be able to assess carious tissue removal, i.e., what was removed, what was left, and how exactly this was done. Often, removal strategies had been termed as “complete” or “incomplete.” However, this was not grounded in any evidence: Carious tissue removal strategies should not pretend to remove specific carious tissues, giving them names like “complete” or “incomplete” excavation, as it remains completely unclear what is completely or incompletely removed (bacteria? soft dentin? discolored dentin? hydrolytically degraded collagen?), but also numerous studies found all removal strategies to be somewhat “incomplete” “complete” (mainly as the gradual changes between different dentin “zones” will not be assessable clinically). Instead, strategies should be termed according to what is done, i.e., descriptively, instead of what one aims to remove or retain.

The hardness criterion has been validated against clinical outcomes in several studies [75] and is assessed using probes or via tactile feedback during excavation. There are further criteria, like dentin color (which is highly unreliable and possibly affected by the incorporation of external stains, i.e., from existing amalgam restorations, as shown in . Fig.  6.49a, b), lesion activity status (active lesions have yellowish or slightly brownish appearance, while the inactive ones are often highly stained, as shown in . Fig. 6.49c, d), fluorescence-­based methods (which target bacterial removal, which is not a good criterion if working close to the pulp, as remaining bacteria may be sealed, while over-invasive removal of bacteria will lead to pulp exposure) [75], or caries detector dyes (which are not at all recommended to be used in pulpal areas of a cavity, as they are neither reliable nor valid, increasing the risk of pulp exposure dramatically) [75]. In summary, using the hardness criterion will allow the dentist to, somewhat reliably, assess carious tissue removal. Based on the agreed principles, and understanding that bacteria may be sealed beneath restorations, five main carious removal strategies have been defined. These are described below [76].  

 

6.5.5.1

Nonselective Removal to Hard Dentin

Nonselective removal to hard dentin (formerly also known as “complete removal”) aims to remove soft dentin, stopping the removal only when hard dentin (similar to healthy dentin) is reached. This is done everywhere in the cavity: as the same criterion (the same endpoint) of carious tissue removal is used both peripherally and pulpally, it is termed nonselective (compare with selective removal; see below) [64]. Nonselective removal to hard dentin bears significant risks for the pulp when applied to in deep lesions [77, 78] and is not recommended any longer [65].

217 General Principles of Tooth Preparation and Carious Tissue Removal

a

b

c

d

..      Fig. 6.49  a Old amalgam restoration being removed; b stained dentin due to the metal corrosion; c brownish appearance of caries-affected dentin in active lesion on the pulpal wall; d highly stained dentin in inactive lesions (arrows)

6.5.5.2

Selective Removal to Firm Dentin

In selective removal, not one but different criteria (endpoints) are used to assess carious tissue removal in the periphery of the cavity and in proximity to the pulp. As described above, one guiding principle is to allow the best adhesive seal of a restoration in the periphery of the cavity. Such aim can be achieved when “sound” enamel and hard dentin are left in the periphery. This approach also serves another guiding principle: maximizing restoration longevity. In the pulpal area of a cavity, however, another criterion (endpoint) is used, with firm dentin being left [64]. Such firm dentin is physically resistant to hand excavator. This approach is recommended for shallow or moderately deep lesions, but not deep lesions (i.e., those extending beyond the pulpal third or quarter of the dentin radiographically). 6.5.5.3

Selective Removal to Soft Dentin

Selective removal to soft dentin is recommended for deep carious lesions in teeth with vital painless pulps. Here, in the pulpal area of a cavity, to avoid pulp exposure and maintain residual dentin thickness is prioritized (. Fig. 9.18). Consequently, it is accepted to leave leathery or, if needed, soft carious dentin in the pulpal aspect of the cavity, serving the  

guiding principle of maintaining pulp vitality. In the periphery, achieving a good seal and maximizing restoration survival are prioritized, with peripheral enamel and dentin again being hard at the end of the removal process. Selective removal to soft dentin has been shown to reduce the risk of pulpal exposure compared with nonselective removal to hard or selective removal to firm dentin. Note that this removal technique has been previously known as partial or incomplete removal.

Stepwise Excavation Stepwise excavation (or removal) involves “selective removal to soft dentin” at Stage 1, followed 6–12 months later by “selective removal to firm dentin” for Stage 2 (. Fig. 9.19). Stage 1 has the same carious tissue removal aims as “selective removal to soft dentin” with soft dentin being left pulpally. The periphery of the cavity should be hard – with similar appearance and tactile characteristics to sound dentin. A provisional restoration is placed with a restorative material that is considered suitable to last for up to 12 months. The subsequent removal of this provisional restoration should then be followed by the “selective removal to firm dentin” pathway with placement of a definitive restoration aiming for longevity. This technique has previously been also known as “two-step excavation.”  

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6.5.6

Finishing of the Enamel Walls

Even though it is the hardest tissue of the human body, the enamel is the weakest one when undermined. The prism’s core is stronger than the interprismatic enamel. Therefore, when pushed, it generally cracks  in the interprismatic enamel following the long axis the prisms. As it has already been mentioned, while the undermined enamel can be preserved when performing an adhesive restoration, because it is protected by the restorative material, for non-adhesive restorations it is essential its removal or protection via a base material. The purpose of the finishing of the enamel walls, for an amalgam restoration, is to remove the irregularities and undermined enamel prisms left by the initial prepara-

tion steps, to ensure that just full-length enamel prisms remained, creating the best marginal sealing as possible between the restorative material and the tooth structure [4]. According to Black, it is the last cutting step to be performed and can be done with the rubber dam isolation already in position [4, 5, 43]. The procedure for the removal of the undermined enamel prisms is called marginal trimming. In order to perform this step on the CS angle of the gingival wall, in Class II preparations, the direction of the prisms has to be followed, cutting them about 15–20° in relation to a line perpendicular the long axis of the tooth, creating a slightly bevel (. Fig. 6.50). The finishing also must be performed on the CS angles of the buccal and lingual walls of proximal boxes, in Class II preparations, removing the remaining undermined enamel that was left after the use of rotary instrument (. Fig. 10.15).  

 

6.5.7

15 a 20°

..      Fig. 6.50  Slight marginal trimming of the enamel on the region of the cavosurface angle of the gingival wall

a

Cleaning of the Cavity

The cavity cleaning is performed after the isolation of the operating field, to remove all the residues and lose debris that deposited during the cutting procedures, before starting the restoration [5, 15]. It is known that after the end of tooth preparation, residues of oil from the high- and lowspeed handpieces, saliva, blood, bacterial biofilm, lose debris, and abrasive fragments from the rotary instruments, among others, remain in contact with the cavity, besides remaining fragments of enamel and dentin [4, 45]. All those residues forms over the CWs a smear layer of about 1–3 μm (. Fig.  6.51a) as well as smear plugs (. Fig. 6.51b) [16].  

 

b

7 um ..      Fig. 6.51  a Smear layer covering the cavity wall; b smear plug (arrow)

219 General Principles of Tooth Preparation and Carious Tissue Removal

Anionic detergents based on sodium lauryl sulfate, antimicrobial agents like 2% chlorhexidine gluconate solution or alkaline solutions of calcium hydroxide have been used for cavity cleaning or disinfection (. Fig. 6.52a–e). The use of a chlorhexidine solution presents also the advantage of being able to deactivate the dentin matrix metalloproteinase enzymes (MMP), which are released by the demineralization promoted by the bacterial acids, responsible for the formation of the carious lesions. Those enzymes are responsible for the hydrolysis of the exposed collagen, favoring the progression of the carious lesion. When chlorhexidine is applied on the cavity for 10–15 s, it is capable to chelate the Zn2+ ions and results in the inactivation of the metalloproteinases [79].  

One option when performing amalgam restorations is to apply a 2% neutral sodium fluoride solution on the preparation walls. This procedure will promote the deposition of calcium fluoride over the walls, acting as a fluoride reservoir that will be released if there is a drop in the pH. The application of the fluoride solution reduces up to 60% of the formation of secondary caries on the amalgam restoration margins and interface. For adhesive restorations, the surface treatment will depend on the bonding system used. Etch-and-rinse adhesives require the previous etching of the preparation walls with a 32–37% phosphoric acid gel, which removes the smear layer and open of the dentin tubules (. Fig. 6.53a), creating microporosities in the enamel (. Fig.  6.53b). The enamel etching increases the surface area available for bonding by  10 to 20 times [3]. After the application and curing of an adhesive, resin tags will be created in the enamel and allow a micromechanical retention. The dentin collagen network, exposed by the acid etching, is impregnated by the adhesive monomers forming the hybrid layer, hence promoting the adhesion to the dentin. For the self-etching systems, phosphoric acid gel is not used, and the smear layer is dissolved by the acidic resinous monomers in its composition. Self-etch adhesives are capable to penetrate through the smear layer and interact with the underlying dentin, creating a hybrid layer. Overall, however, the effects of the antimicrobial agents can be only superficial, due to the presence of the residual bacteria inside the dentin tubules and within the smear layer. However, considering what was explained before, the relevance of the cavity disinfection is questioned anyway. Sealing the cavity seems more relevance than performing such disinfection.  

 

..      Fig. 6.52  Substances for cavity cleaning. a 11.5% polyacrylic acid; b calcium hydroxide solution; c 2% chlorhexidine digluconate; d anionic detergent; e 37% phosphoric acid gel

a

b

..      Fig. 6.53  a Opening of the dentin tubules by the acidic etching on the right side of the image. The left side remained covered by the smear layer; b Etching pattern of enamel

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Conclusion

6

Caries is no longer understood as an infectious disease, but rather as an ecological imbalance within the biofilm, which is shifted toward acidogenic and aciduric bacteria, associated with the high consumptions of fermentable carbohydrates. Therefore, if the carbohydrates can be controlled, so can the biofilm, recovering the ecological balance and the oral health. However, in cavitated lesions, it is not possible to control the biofilm by regular tooth cleaning techniques, such as brushing and flossing. In this case, the dental restorations are still recommended, and the cavity preparation is required. The restorations can be performed with nonadhesive or adhesive materials. Although the use of nonadhesive restorations performed with dental amalgam is reducing nowadays, it is still used in many situations. For this material, special characteristics of the preparation are required, in order to provide a long-lasting restoration. On the other hand, adhesive materials, such as composite resins and glass ionomer cements, are able to bond to the remaining tooth structure, creating its reinforcement. In this case, the actual shape of the cavity is less important than to provide an adequate marginal sealing for the restoration. In this chapter, the biological and mechanical principles of the toot preparation were presented, as well as the traditional steps of tooth preparation, which can guide the dental students to easily obtain the desired preparation characteristics. The current principles are based on the maximum preservation of the remaining tooth structure, creating a defect-oriented preparation.

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endodontically-treated maxillary premolars. Oper Dent. 2010;35: 599–604. https://doi.org/10.2341/10-064-C. 38. Plasmans PJ, Kusters ST, de Jonge BA, van’t Hof MA, Vrijhoef MM. In vitro resistance of extensive amalgam restorations using various retention methods. J Prosthet Dent [Internet]. 1987 [cited 2019 May 24];57:16–20. 39. Anusavice KJ. Phillips science of dental materials. 11th ed. London: Elsevier; 2005. 40. Dawson M, Soro V, Dymock D, Price R, Griffiths H, Dudding T, et al. Microbiological assessment of aerosol generated during debond of fixed orthodontic appliances. Am J Orthod Dentofac Orthop [Internet]. 2016 [cited 2019 May 25];150:831–8. https://doi.org/10.1016/j. ajodo.2016.04.022. 41. Hovliaras CA. Preprocedural rinsing in the dental office: a consideration for improved infection control among the dental team and patients. J N J Dent Assoc [Internet]. 2013 [cited 2019 May 25];84:27–31. 42. Shetty SK, Sharath K, Shenoy S, Sreekumar C, Shetty RN, Biju T. Compare the efficacy of two commercially available mouthrinses in reducing viable bacterial count in dental aerosol produced during ultrasonic scaling when used as a preprocedural rinse. J Contemp Dent Pract [Internet]. 2013 [cited 2019 May 25];14:848–51. 43. Black GV.  A work on operative dentistry. Chicago: Medico-Dental Publishing Company; 1908. 44. Christensen G.  Alternative for class II restorations. Clin Res Assoc Newslett. 1994;18:1–2,7. 45. Horsted-Bindslev P, Mjör IA.  Modern concepts in operative dentistry: Wiley-Blackwell; 1989. 46. Markley M.  Restorations of silver amalgam. J Am Dent Assoc. 1951;43:133–46. 47. Gilmore HW, Lund MR. Operative dentistry. Saint Louis: Mosby; 1973. 48. Simon WJ.  Clinical operative dentistry. Philadelphia: Saunders; 1956. 49. Howard WW. Atlas of operative dentistry. 2nd ed. St. Louis: Mosby; 1973. 50. Hollenback GM.  The economic value of amalgam in operative dentistry and the technic of its use. J Am Dent Assoc Dent Cosm [Internet]. 1937;24:1318–26. https://doi.org/10.14219/jada. archive.1937.0233. 51. Stratis S, Bryant RW. The influence of modified cavity design and finishing techniques on the clinical performance of amalgam restorations: a 2-year clinical study. J Oral Rehabil [Internet]. 1998 [cited 2019 May 22];25:269–78. 52. de Vree JH, Peters MC, Plasschaert AJ. The influence of modification of cavity design on distribution of stresses in a restored molar. J Dent Res [Internet]. 1984 [cited 2019 May 22];63:1217–20. https:// doi.org/10.1177/00220345840630101001. 53. Symons AL, Wing G, Hewitt GH. Adaptation of dental amalgam to the cavosurface margin of Class I cavity preparations. J Oral Rehabil [Internet]. 1987 [cited 2019 May 22];14:65–76. 54. Bryant RW. The influence of modified cavity design and finishing techniques on the margin region of amalgam restorations: a simulated clinical study. Aust Prosthodont J [Internet]. 1992 [cited 2019 May 24];6:39–45. 55. Elderton RJ.  Cavo-surface angles, amalgam margin angles and occlusal cavity preparations. Br Dent J [Internet]. 1984 [cited 2019 May 22];156:319–24. 56. Akerboom HB, Advokaat JG, Van Amerongen WE, Borgmeijer PJ.  Long-term evaluation and rerestoration of amalgam restorations. Community Dent Oral Epidemiol [Internet]. 1993 [cited 2019 May 22];21:45–8. 57. Mondelli J, Ishikiriama A, Galan JJ, Navarro MF.  Dentística operatória. São Paulo: Sarvier; 1976. 58. Massler M, Barber TK.  Action of amalgam on dentin. J Am Dent Assoc [Internet]. Elsevier; 1953 [cited 2019 May 22];47:415–22. https://doi.org/10.14219/JADA.ARCHIVE.1953.0197. 59. Fichmann DM, Santos W.  Restaurações à amálgama. Savier: São Paulo; 1982.

60. Granath LE. Photoelastic model experiments on class II cavity restorations of dental amalgam. Odontol Rev. 1965;16:7–38. 61. Mahler DB. An analysis of stresses in a dental amalgam restoration. J Dent Res [Internet]. SAGE Publications Sage CA: Los Angeles; 1958 [cited 2019 May 22];37:516–26. https://doi.org/10.1177/002203455 80370032301. 62. Mooney B. Operatoria dental. Buenos Aires: Panamericana; 1995. 63. Crockett WD, Shepard FE, Moon PC, Creal AF. The influence of proximal retention grooves on the retention and resistance of class II preparations for amalgams. J Am Dent Assoc. 1975;91:1053–6. 64. Innes NP, Frencken JE, Bjorndal L, Maltz M, Manton DJ, Ricketts D, et  al. Managing carious lesions: consensus recommendations on terminology. Adv Dent Res. 2016;28:49–57. https://doi. org/10.1177/0022034516639276. 65. Schwendicke F, Frencken JE, Bjorndal L, Maltz M, Manton DJ, Ricketts D, et al. Managing carious lesions: consensus recommendations on carious tissue removal. Adv Dent Res. 2016;28:58–67. https://doi. org/10.1177/0022034516639271. 66. Bjørndal L, Reit C, Bruun G, Markvart M, Kjaeldgaard M, Näsman P, et al. Treatment of deep caries lesions in adults: randomized clinical trials comparing stepwise vs. direct complete excavation, and direct pulp capping vs. partial pulpotomy. Eur J Oral Sci [Internet]. 2010 [cited 2019 May 22];118:290–7. https://doi.org/10.1111/j.16000722.2010.00731.x. 67. Schwendicke F, Stolpe M, Meyer-Lueckel H, Paris S, Dörfer CE. Costeffectiveness of one- and two-step incomplete and complete excavations. J Dent Res [Internet]. 2013;90:880–7. 68. Whitworth JM, Myers PM, Smith J, Walls AW, McCabe JF.  Endodontic complications after plastic restorations in general practice. Int Endod J. 2005;38:409–16. https://doi.org/10.1111/ j.1365-2591.2005.00962.x. 69. Hevinga MA, Opdam NJ, Frencken JE, Truin GJ, Huysmans MC.  Does incomplete caries removal reduce strength of restored teeth? J Dent Res [Internet]. 2010;89:1270–5. https://doi. org/10.1177/0022034510377790. 70. Schwendicke F, Kern M, Blunck U, Dorfer C, Drenck J, Paris S. Marginal integrity and secondary caries of selectively excavated teeth in  vitro. J Dent. 2014;42:1261–8. https://doi.org/10.1016/j. jdent.2014.08.002. 71. Schwendicke F, Kern M, Meyer-Lueckel H, Boels A, Doerfer CE, Paris S.  Fracture resistance and cuspal deflection of incompletely excavated teeth. J Dent. 2013;42:107–13. 72. Bakhshandeh A, Qvist V, Ekstrand K. Sealing occlusal caries lesions in adults referred for restorative treatment: 2–3 years of follow-up. Clin Oral Investig [Internet]. Springer Berlin/Heidelberg; 2012;16:521–9. https://doi.org/10.1007/s00784-011-0549-4. 73. Hesse D, Bonifacio CC, Mendes FM, Braga MM, Imparato JC, Raggio DP.  Sealing versus partial caries removal in primary molars: a randomized clinical trial. BMC Oral Health. 2014;14:58. https://doi. org/10.1186/1472-6831-14-58. 74. Mertz-Fairhurst EJ, Curtis JW Jr, Ergle JW, Rueggeberg FA, Adair SM. Ultraconservative and cariostatic sealed restorations: results at year 10. J Am Dent Assoc. 1998;129:55–66. 75. Schwendicke F, Paris S, Tu YK. Effects of using different criteria and methods for caries removal: a systematic review and network metaanalysis. J Dent. 2015;43(1):1–15. 76. Innes N, Schwendicke F. In: Schwendicke F, editor. Management of deep carious lesions: Springer; 2017. 77. Ricketts D, Lamont T, Innes NP, Kidd E, Clarkson JE. Operative caries management in adults and children. Cochrane Database Syst Rev. 2013;28:CD003808. 78. Schwendicke F, Dorfer CE, Paris S.  Incomplete caries removal: a systematic review and meta-analysis. J Dent Res. 2013;92:306–14. https://doi.org/10.1177/0022034513477425. 79. Zhang S, Kern M. The role of host-derived dentinal matrix metalloproteinases in reducing dentin bonding of resin adhesives. Int J Oral Sci. 2009;1:163–76. https://doi.org/10.4248/IJOS.09044.

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Isolation of the Operating Field Alessandra Bühler Borges, Carlos Rocha Gomes Torres, Ana Raquel Benetti, and Azam Bakhshandeh 7.1

Introduction – 224

7.2

Isolation Using Rubber Dam – 224

7.2.1 7.2.2 7.2.3 7.2.4 7.2.5 7.2.6 7.2.7 7.2.8 7.2.9 7.2.10

 ubber Dam – 224 R Rubber Dam Frame – 225 Punch – 225 Clamps – 226 Forceps – 232 Other Retainers – 233 Number of Teeth to be Isolated – 234 Technique for Isolation Using Rubber Dam – 234 Modified Techniques for Isolation in Special Clinical Situations – 246 Sealing Leakage on the Rubber Dam Isolation – 248

7.3

Using Cotton Rolls Combined with Suction – 248

7.3.1 7.3.2 7.3.3 7.3.4 7.3.5 7.3.6

S aliva Ejector and High-Volume Evacuators – 250 Cotton Rolls and Absorbent Pads – 251 Cheek and Tongue Retractors – 254 Light-Cured Gingival Barriers – 255 Gingival Retraction Cords – 255 Cotton Roll Isolation Technique – 256

References – 260

© Springer Nature Switzerland AG 2020 C. R. G. Torres (ed.), Modern Operative Dentistry, Textbooks in Contemporary Dentistry, https://doi.org/10.1007/978-3-030-31772-0_7

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Learning Objectives The learning objectives of this chapter are related the following topics: 55 To understand the importance of isolation of the operating field 55 To become acquainted to the instruments and consumables used for that procedure 55 To acquire knowledge about the techniques employed for controlling the moisture on the operating field

7.1

7

Introduction

Certain dental treatment procedures require a clean and dry working field. The isolation of the operating field aims primarily to control moisture and avoid contamination from microorganisms or saliva during treatment. It can be obtained in two ways: (1) by application of a rubber dam or (2) by using saliva absorbers, such as cotton rolls, saliva ejectors, and retraction cords. Evidence regarding which is the best method to obtain a clean and dry operating field is limited. A systematic review published in 2016 found only low-quality evidence studies suggesting that the use of rubber dam during direct restorative procedures may lead to a lower failure rate of the restorations, when compared to the failure rate registered for restorative procedures conducted under isolation with cotton rolls [1]. Further high-quality studies investigating the impact of the use of rubber dam during different restorative procedures are recommended. The limited evidence is, according to some authors, not sufficient to support changes to current practice regarding the placement of direct restorations [2]. Although it appears very difficult to scientifically prove the impact of the use of rubber dam on the final outcome of restorative procedures, [3] consensus exists towards the need of a clean surface and moisture control when bonding to teeth – regardless of the method used to achieve this. A meta-analysis on the clinical outcome of non-­retentive and cervically placed composite restorations, identified a significantly higher retention rate of such restorations placed using rubber dam [4]. As a rule of thumb, the use of rubber dam is preferred over the use of cotton rolls combined with effective suction to obtain a clean and dry operating field for a number of restorative procedures, the reasons are explained in details in the sections to come. Though it is valid to point out that both techniques have advantages and limitations, thus an individual assessment may be necessary to guarantee that the best technique is employed for each clinical situation. 7.2

Isolation Using Rubber Dam

The use of a rubber dam was introduced by Sanford Christie Barnum [5, 6] to completely eliminate fluids from the operating field. If well performed, the moisture control with its use is simple and effective; hence it is highly recommended to maintain the teeth dry during restorative procedures. Further

important advantages are obtained when isolating the operating field by using a rubber dam: this ensures (1) retraction and protection of the patient’s soft tissues, (2) protection of the patient’s respiratory and digestive tracts, and (3) improvement of access to visualization of the operating field, thus allowing the dentist to concentrate on the treatment to be performed. In addition, it avoids interruptions of the treatment, otherwise necessary to change cotton rolls and retract soft tissues [7]. The use of rubber dam is also important during excavation of deep carious tissue, as it prevents the contamination of the pulp from microorganisms present in the oral fluids, specially in the case of an accidental pulp exposure during excavation. During the removal of amalgam restorations, the use of a rubber dam prevents the patient from swallowing amalgam residues. Other than allowing a clean and dry operating field, with an adequate moisture control by exclusion of saliva, crevicular fluid, and occasional bleeding, the use a rubber dam may aid obtaining optimal conditions for the dental materials, whose properties may become impaired by early contact with moisture [1]. Regarding protection of the patient, the use of a rubber dam eliminates the risk of the patient swallowing or aspirating materials or instruments that are used during the operative procedures, and reduces the risk of accidental damage to the patient’s soft tissues. The rubber dam also benefits the dentist and the dental team because it reduces dispersion of oral microorganisms to the working environment. Improved efficiency is expected when the rubber dam is in place due to simplification of the restorative procedures, and the reduction of time spent with patient expectoration and conversation [5, 8]. Some dentists avoid placing the rubber dam, justifying as main reasons the lack of supporting evidence, additional time spent with this procedure and the unwillingness of the patients [4]. However, training leads to improvement of the technique and consequently reduction of the working time. Additionally, if the patients are well-informed about the improved prospect of the dental work performed using the rubber dam, they often accepts its use. There are, however, cases shown impossible or very difficult to use a rubber dam. Examples are teeth on initial stages of eruption, misaligned teeth, patients with breathing problems, and lack of latex-free rubber dam for patients with allergy to latex [8]. In such cases, proper moisture control of the operating field shall be achieved using cotton rolls and effective suction. 7.2.1 

Rubber Dam

The rubber dam isolates the operating field from the oral cavity. It is often fabricated with natural latex and is available in several colors. Latex-free sheets made of silicone or nitrile rubber are also available and are indicated for patients allergic to latex. The colors that contrast with the teeth are preferred because they improve the visualization of the preparations’ and restorations’ details. The blue color is ­generally chosen: it is the complementary color to the yellow

7

225 Isolation of the Operating Field

of the teeth, increases the perception of contrast, and is a relaxing color to the vision [9]. Rubber dams are available generally as 13 cm × 13 cm sheets with various thicknesses (thin, medium, thick, and extra thick) (. Fig.  7.1). Thick rubber sheets are easier to pass through tight interproximal contacts, but they tear more easily [3]. On the other hand, thicker rubber sheets are more tear resistant and better to retract the soft tissues [10]. The thick rubber dam is helpful for isolating Class V lesions associated with a cervical retainer. Medium-thick rubber dam is most widespread and is usually preferred as the thin one is more prone to tearing and the extra thick one is more difficult to apply. As latex deteriorates with time, it will tear more easily, and therefore, new rubber sheets must be used [6].  

7.2.2 

Rubber Dam Frame

The rubber dam frame is used to keep the borders of the rubber sheet in position. The rubber sheet must be stretched and fixed on the lateral pins of the frame. Different frame shapes are available. The Young frame has a U-shape with lateral pins used

to fix the rubber sheet (. Fig. 7.2a, b). The Otsby frame has an hexagonal shape, anatomically projected for better contouring the face of the patient (. Fig. 7.3a, b), thus allowing some distance between the rubber dam and the patient’s nose for more comfortable breathing [11]. Rubber dam frames are made of metal or plastic, the latter does not interfere on the uptake of radiographic images during the operative procedures. There are also frames integrated to the rubber sheet, aiming to simplify the placement of the rubber dam: these have high flexibility and may reduce the need of clamps (ex. Optradam Ivoclar-Vivadent) (. Fig. 7.4a–d).  

 

 

7.2.3 

Punch

The punch forceps is used to perforate the rubber sheet in the positions where the teeth to be isolated shall fit. The Ainsworth punch is commonly used: it has a plunger with a sharp end and a rotating disk-shape metal table with several holes (. Fig.  7.5a). These perforating holes have different diameters to better fit the teeth. The Ivory punch also has a rotating metal disk with perforating holes of distinct diameters (. Fig.  7.5b). The diameter of the perforating hole must be selected according to the cervical diameter of each tooth, generally following the sequence presented in . Fig.  7.6. However, variations are sometimes needed, depending on the tooth size, the dentist choice, and rubber sheet thickness [6]. In order to perforate the rubber sheet, the plunger should be placed over the pre-marked positions and pressed firmly. It is easier to perforate the rubber when the sheet is under slight tension, but not attached to one of the sides of the frame (. Fig. 7.7a). It is important that the punch can deliver perfect and complete perforations (. Fig.  7.7b). Incompletely cut perforations easily result in tear of the rubber during manipulation or may lead to penetration of saliva after the rubber dam is in place (. Fig. 7.7c) [12]. In order to avoid these problems, the perforating table of the punch shall always be sharp; if necessary, the punch can be sharpened.  

 

 

 

 

 

..      Fig. 7.1  Rubber dam sheets with different colors

a

..      Fig. 7.2  Young frames. a Plastic; b metallic

b

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a

7

b

..      Fig. 7.3  Ostby frames. a Plastic; b metallic

a

b

c

d

..      Fig. 7.4  Frame integrated to the rubber dam (ex. OptraDam, Ivoclar Vivadent). a Frontal view of the set showing the extension of the sheet for lip protection; b back view of the set, showing the

7.2.4 

Clamps

Clamps are used to secure the rubber sheet in place and are generally made of a flexible metal. The clamps should be placed on the tooth that is more distal on the arch to the tooth in which the treatment is to be performed, particularly when isolating posterior teeth. The most distally placed clamp must resist traction from the rubber towards the frame. Anywhere

marking for punching; c application into the patient’s mouth; d rubber dam isolation finished

else in the isolated quadrant, additional clamps can be used to retract the gingiva whenever necessary. Clamps are available in different sizes and specifically adapt to each group of teeth. They are composed by the bow that connects two horizontal jaws (. Fig. 7.8). Those jaws present prongs that grip the tooth cervically below its largest circumference, while the round holes, are used for fitting the forceps. They also present rectangular holes, which allow placing a bold hand instrument for  

227 Isolation of the Operating Field

a

b

..      Fig. 7.5  Punch forceps. a Ainsworth; b Ivory

..      Fig. 7.6  Detail of the perforating holes in the rotating metal table on the Ainsworth punch and their corresponding group of teeth. The largest hole is used to make perforations for anchor molars

transposing the rubber sheet underneath the wings of the clamp (. Fig. 7.33i). Some clamps have wings (. Fig. 7.9a, c) that allow attaching the clamp in the rubber dam (. Fig. 7.33a– d), while others are wingless (. Fig. 7.9b, d). The clamps recommended for posterior teeth have one bow, while those used in anterior teeth possess two bows (. Fig. 7.9). The clamps are flexible and can be opened with the aid of the forceps to trespass the largest circumference of the tooth. When in position, the clamp is released to grip the cervical area of the tooth (. Fig.  7.10a, b). Winged clamps are more bulky and can therefore interfere with the matrix, the matrix holder, or the wedges used in the restorative procedure [5, 10, 13]. Several models of clamps are available on the market; this chapter shows, among a variety of clamps, the winged clamps No. 200–205 used on molars, No. 206–209 used on premolars, and No. 210–211 used on maxillary and mandibular incisors, respectively (. Fig.  7.11a–c). The chapter includes  

 

 

 

 

 

 

also a variety of smaller, wingless clamps and describes later their placement techniques (. Fig. 7.11d). In some situations a clamp can be modified to individually adapt to a specific case. This is achieved by heating the jaws of the clamp until they become red hot and then immediately submerging it in water. The necessary modifications are made on the jaws by bending them using flat pliers or, when necessary, cutting them with mounted stones. The clamp is tempered by heating it again on a flame, up to a slightly lower temperature, and submerging it in oil (. Fig.  7.12a–g) [7]. This could be advantageous for clamp no. 212 to adjust the facial jaw to a more cervical position on the tooth crown, thus allowing retraction of gingiva and exposure of the gingival margins of the cavity. Gingival retraction clamps (. Fig. 7.13a, b) are designed to be used in teeth that are not completely erupted and if lesions are too close to the gingival level. In these clamps, the jaws are  

 

 

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a

7

b

c

..      Fig. 7.7  Punching the rubber dam. a Punch in position with rubber dam under slight tension; b complete and correct perforations; c inadequate partial perforations, which increase the risk of tearing the rubber

..      Fig. 7.8  Components of the clamps

BOW

JAW

HOLE FOR FORCEPS

WING

PRONG

RECTANGULAR HOLE

229 Isolation of the Operating Field

..      Fig. 7.9  a Winged clamp with one bow; b wingless clamp with one bow; c winged clamp with two bows; d wingless clamps with two bows. The red arrows indicate the wings

a

b

c

d

a

b

..      Fig.7.10  a Winged clamp at rest; b flexibility is shown when the clamp is opened by the forceps

a

0

00

2

2A

206

207

208

209

b

3

7

8

200

201

202

..      Fig. 7.11  Clamps most commonly used in operative dentistry. a Winged clamps for premolars; b winged clamps for molars; c clamps for anterior teeth; d wingless clamps for premolars (top row) and molars (bottom row)

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c

d 210

W2A

29

211

W8A

7

27

26

28

W56

..      Fig. 7.11 (continued)

a

b

c

d

..      Fig. 7.12  a Clamp number 212 in its original shape; b exposure of the clamp’s jaws to the flame; c immersion into water; d modifications on the clamp are made using two flat pliers to bend the facial jaw apically; e the jaws are exposed again to the flame; f the clamp

is then immersed in oil for tempering; g final shape of the clamp with the facial jaw on a more apical position to retract the gingival tissues

231 Isolation of the Operating Field

e

f

g

..      Fig. 7.12 (continued)

a

..      Fig. 7.13  a Examples of gingival retractor clamps for posterior teeth, with jaw and prongs on a more apical position (arrows); b retractor clamps no. 212 (upper image), 212R (lower right),

b

and 212L (lower left). Clamps 212R and 212L allow the restorative procedure to be made simultaneously in adjacent teeth

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a

7

b

..      Fig. 7.14  a Retraction clamp no. 212 with jaws at the same alignment; b clamp no. 212M modified by the manufacturer, with the facial jaw on a more cervical position to improve gingival retraction during restoration of class V cavities

a

b

c

..      Fig. 7.15  Clamp forceps. a Palmer; b Brewer; c Ivory

directed gingivally to allow anchorage on a more cervical region of the tooth. For a single cervical restoration, the regular 212 clamp is recommended, while for two restorations on neighboring teeth, clamps 212R and 212L are used simultaneously (. Fig. 7.13b). For an extra gingival retraction on anterior teeth or premolars, the gingival retraction clamp no. 212 can be customized as mentioned earlier (. Fig. 7.12a–g) or can be purchased already modified by the manufacturer (. Fig. 7.14a, b).  

 

 

7.2.5 

Forceps

The clamp holding forceps is used to securely position the clamp on the tooth. The most commonly used forceps are Palmer (. Fig.  7.15a), Brewer (. Fig.  7.15b), and Ivory (. Fig.  7.15c), which vary according to the angle of the shank and the presence or not of curvature towards the active tip. The Palmer forceps is mono-angled and can pres 

 

 

233 Isolation of the Operating Field

ent a knurled surface or notches in the active end (. Fig. 7.16a, b) to fit the holes on the clamps.  

7.2.6 

Other Retainers

Besides using clamps, the rubber dam can be retained and stabilized using other types of retainers.

7.2.6.1

Ligatures

Dental floss is used to stabilize the rubber dam and to retract the gingiva. There is no need to make ligatures in every tooth; this procedure is only needed where it is difficult to invert the rubber dam or if gingival retraction is desired. A piece of dental floss is then used to embrace the cervical area of the tooth, and, with the aid of a bold hand instrument that pushes the dental floss apically, the floss is directed towards the gingival crevice. After the margins of the perforation on the rubber dam are effectively inverted, the floss is tied on the facial side with a double knot first, followed by a simple knot for stabilization (. Fig. 7.17a–f) [14].  

Tip

Ligatures with a double knot are difficult to perform when the operator is unassisted and should preferably be performed with help. The operator and assistant have to ensure that the knot is in the right position, retracting the gingiva, and not sitting loose around the cervical areas of the tooth.

a

b ..      Fig. 7.16  Detail of the tip of the Palmer forceps. a With slots; b with a knurled surface

It is also possible to make ligatures with a running knot, where a running loop is made outside the mouth and the dental floss

a

b

c

d

..      Fig. 7.17  Sequence to prepare ligatures using double knots with dental floss. a Introduction of the dental floss into the crevice; b, c double knot (surgeon knot) used to stabilize; d, e simple knot used to fix the ligature; f ligatures finished

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e

7

f

..      Fig. 7.17 (continued)

is then adapted around the tooth and tied (. Fig.  7.18a–i). Another simple knot is made over the first knot for fixation of the ligature. If no additional gingiva retraction is desired, the dental floss is then cut next to the knot.  

Tip

Ligatures using a running knot are more stable and therefore preferred. It is also possible to use this ligature when working unassisted.

 tabilizing Cords, O-rings, and Elastic S Ligatures

7.2.6.2

Dental dam stabilizing cords are made of natural latex (. Fig.  7.19a) and available in various diameters. They can sometimes substitute clamps or ligatures if the rubber dam is placed on the anterior and premolar regions. The stabilizing cords are used on the most distal tooth when isolating the anterior teeth (. Fig.  7.19b) or on the most mesial tooth when isolating posterior teeth (. Fig.  7.19c). Alternatively, pieces of the rubber sheet can be used to stabilize the rubber dam (. Fig.  7.20a–c). O-ring ligatures commonly used in orthodontics to fixate the archwire onto the brackets are also suitable to stabilize the rubber dam in the gingival area. The O-rings can be stretched and brought onto the teeth by using either the forceps or two opposing pieces of dental floss (. Fig. 7.21a–f) [14]. Elastic ligatures can also be used to stabilize the rubber dam. They are available in two shapes, for anterior and posterior teeth, respectively, and can in some situations replace the use of clamps (. Fig. 7.22a, b).  

 

 

 

 

 

7.2.7 

Number of Teeth to be Isolated

For some procedures in operative dentistry, it is enough to place the rubber dam on only one tooth (. Fig. 7.23): when there is no involvement of the approximal region or when there is only one tooth on the hemiarch.  

>> The clamp may in some situations be placed directly on the tooth which will receive treatment, such as single restorations of class I, class V, or sealing of occlusal pits and fissures, as well for endodontic treatment or internal bleaching.

In cases of class II preparations, a minimum of one tooth mesially and one distally to the tooth being treated should be isolated. This allows anatomical visualization of the adjacent teeth used for reference during build up of the restoration, and allows the placement of matrices and wedges. Some authors suggest the isolation of the entire hemiarch of the region that will be treated, extending the procedure to the lateral incisor or canine of the contralateral hemiarch to improve access and visualization of the operating field [6, 8, 10, 12, 15]. However, this procedure is generally not necessary. >> The clamp shall not be placed directly on the tooth of interest if the restorative procedure involves the interproximal space. This will interfere with positioning the matrice and wedges.

For restorative procedures on anterior teeth, the isolation is preferably made from canine to canine or from premolar to premolar (. Fig.  7.24a, b). In such cases, the use of clamps can often be avoided because the rubber dam can be stabilized using other retainers (. Figs.  7.19b, 7.20c, and 7.21f). Stabilizing cords, O-rings, or elastic ligatures can be tried before deciding for the use of a clamp. For restoration of class V cavities, no. 212 gingival retraction clamp is used to isolate and restore one tooth at a time (. Fig.  7.25a). Clamps no. 212R and 212L can be used to restore two adjacent teeth (. Fig. 7.25b).  

 

 

 

7.2.8 

 echnique for Isolation Using Rubber T Dam

7.2.8.1

Preparation

Firstly, the need for anesthesia must be assessed. Isolation with the rubber dam does not necessarily require anesthesia

235 Isolation of the Operating Field

of the gingival tissues, but is recommended if the gingival retraction clamps are used and, in some cases, when the ligatures are necessary. However, if the restorative treatment requires local anesthesia, this must be applied before placing the rubber dam [14]. The next step is to test the clamp. It is necessary to choose the one that best adapts on the anchor tooth. The choice of clamp is simply based on the fit, which depends on the tooth size, location on the arch, and eruption stage of the anchor tooth. The clamp bow must be directed distally to the anchor tooth.

>> For patient safety, a piece of dental floss (about 30 cm long) must be tied on the clamp holes or bow before inserting it into the mouth to avoid accidental deglutition or aspiration. It can also be tied on both circular holes of the clamp, increasing the safety in the case it breaks on the region of the bow while inside the mouth (. Fig. 7.26a, b).  

The clamp must be opened with the forceps until it trespasses the tooth circumference and grips the cervical region. It is released from the forceps, and its stability on the tooth must

a

b

c

d

e

f

..      Fig. 7.18  Sequence to prepare ligatures using a running knot. a–d Preparation of the running knot outside the mouth. e Placement of the dental floss around the tooth; f tied knot; g, h additional simple knot used for fixation; i ligature finished and cut closely to the knot

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g

7

h

i

..      Fig. 7.18 (continued)

a

b

c

..      Fig. 7.19  a Dental dam stabilizing cord roll used to stabilize the rubber dam (Wedjets – Coltène/Whaledent); b isolation of anterior teeth stabilized distally with the stabilizing cords; c mesial placement of the cord to stabilize the rubber dam during isolation of posterior teeth

237 Isolation of the Operating Field

be verified, by touching the clamp slightly with the tip of the index finger (. Fig. 7.27a, b). If there is lack of stability, the clamp will move, and the efficacy of the procedure will be compromised. Care must be taken to not open the clamp excessively: then there is a risk of the clamp not returning to its original dimension [8].  

a

Before actually placing the rubber dam, the interproximal contacts must be checked with dental floss (. Fig. 7.28). Any sharp regions, such as defective restorations or approximal carious lesions, are likely to tear the rubber sheet, and these areas should be smoothened with the aid of abrasive strips. Smoothing sharp margins  

b

c

..      Fig. 7.20  a A piece of rubber is cut from the edge of the dam; b the piece of rubber is placed distally to the canines when isolating anterior teeth; c isolation finished using pieces of rubber dam for stabilization

a

..      Fig. 7.21  a Orthodontic O-ring ligatures. b the O-ring can be placed at the tip of the Palmer forceps. c stretching of the O-ring with the Palmer forceps. d alternatively, the O-ring can be enlaced with two

b

opposing pieces of dental floss. e stretched O-ring using dental floss. f dental isolation using O-ring ligatures for stabilization

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c

d

e

f

..      Fig. 7.21 (continued)

a

b

..      Fig. 7.22  a Elastic ligatures (Angelus) for anterior (1) and posterior teeth (2); b elastic ligature placed on a molar. Such ligatures could be useful in cases of fissure sealants or alternatively for endodontic treatments

after removing old restorations is also recommended before placing the rubber dam. 7.2.8.2

Preparation of the Rubber Dam

The rubber sheet must be perforated to adjust properly around the teeth to be isolated. There are several techniques to determine the position of the perforations in the rubber dam, such as the use of a stamp (. Fig.  7.29a, b) and tem 

plates (. Fig. 7.30a, b) or by directly marking the position of the perforations in the mouth (. Fig. 7.31a).  

 

Stamps Stamps (. Fig. 7.29a, b) can be used to print the position of the teeth on the rubber dam. After wetting the stamp with ink, it must be centralized on the rubber dam to transfer the locations of the orifices to be made. This technique allows  

239 Isolation of the Operating Field

marking the rubber dam in advance; later only the positions corresponding to the teeth to be isolated need to be punched. This technique is easy, but it does not allow individualization

of the positions of the teeth and may not be the best option in cases of tooth misalignments or absence of teeth.

Templates Templates (. Fig. 7.30a, b) made of paper or plastic can also be used to mark the position of the orifices on the rubber dam. After placing the template centrally on the rubber sheet, a marker pen is used to mark the position of the orifices. A ballpoint pen should not be used because it does not allow correct marking on the rubber. Similar to the use of stamps, this technique is easy but does not account for individualization of tooth positions in the dental arch.  

Marking the Perforation Positions in the Mouth

..      Fig. 7.23  Placing the rubber dam in only one tooth is sufficient when there is no involvement of the approximal area; here during application of pit and fissure sealant

a

Although the use of stamps or templates is a rather easy way for demarcating the perforations, they lack individualization for the position of the teeth in the patient’s arch. Thus, by marking the position of the perforations in the mouth, it is possible to account for teeth that are misaligned or farther apart from the neighboring teeth. According to this method, the rubber dam must be attached to the frame and placed centrally in the oral cavity. It is important to verify that the b

..      Fig. 7.24  Rubber dam placed to restore anterior teeth without using clamps. a The rubber dam was stabilized using only dental floss ligatures on the canines (arrow). b The ligatures do not hinder positioning the silicone mold used for reconstruction of the fractured teeth

a

b

..      Fig. 7.25  a Gingival retraction clamp number 212 applied to isolate only one tooth; b gingival retraction clamps 212L and R used for simultaneous isolation and exposure of the cervical margins of two adjacent teeth

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a

7

b

..      Fig. 7.26  a A piece of dental floss is tied onto the clamp to increase the safety during the placement into the mouth. b dental floss tied on both circular holes of the clamp, increasing the safety in case it breaks on the region of the bow while inside the mouth

a

b

..      Fig. 7.27  a Testing the clamp onto the tooth; b verification of the clamp stability with the finger

under the rubber sheet. A marker pen is then used to mark the center of the occlusal surface of posterior teeth (. Fig.  7.31a) and the center of the incisal edge of anterior teeth. In the absence of teeth, the corresponding space shall remain unmarked.  

7.2.8.3

Punching the Rubber Dam

The marks on the rubber dam must now be perforated by pressing the punch firmly. The size of the perforations must correspond to the size of the teeth, as described previously. In order for the punch to reach all marks, the rubber sheet must be partially removed from the frame (. Fig. 7.32).  

7.2.8.4 ..      Fig. 7.28  Verification of interproximal contacts with dental floss to make sure it will be possible to pass the rubber between the teeth without tearing

position of the rubber dam in the mouth leaves the nose free from contact with the rubber [16]. Using the tip of the fingers, the rubber dam must be stretched towards the teeth to be isolated, so it is possible to see the contour of the teeth

Placing the Rubber Dam

The rubber dam can be placed in the patient’s mouth using different techniques as described below.

Placement of the Whole Set: Clamp, Dam, and Frame In this technique, winged clamps must be used. The appropriate clamp is selected and tested beforehand, tied to dental floss. The wings must be attached to the perforation corre-

7

241 Isolation of the Operating Field

a

b

Maxila

Mandibula

..      Fig. 7.29  a Stamp used to print the position of the teeth on the rubber dam; b marked rubber dam with the stamp

a

b

..      Fig. 7.30  Examples of templates used to mark the rubber dam. a Vivadent; b Ivory

..      Fig. 7.31  Marking the position of the teeth directly in the mouth. The rubber shall be stretched over the teeth and held in position, while the center of the tooth is marked using a permanent marker

sponding to the anchor tooth, the bow directed distally (. Fig. 7.33a–d). The perforations must be lubricated on the side of the rubber sheet to be in contact with the teeth with a water-­soluble lubricant or the patient’s own saliva. Petroleum jelly or oil-based products must not be used because residues  

..      Fig. 7.32  Punching the marked positions on the rubber

on the tooth can impair bonding procedures or damage the rubber dam. The lubrication facilitates the passage of the rubber dam through the interproximal contacts (. Fig. 7.33e). In sequence, the forceps must be engaged on the round holes of the clamp, and the whole set containing the clamp, the rubber dam, and the frame are placed into the mouth  

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of the patient (. Fig. 7.33f–h). The clamp must be opened to allow adaptation onto the cervical area of the anchor tooth. After releasing the clamp from the forceps, the clamp stability must be tested. Thereafter, a bold instru 

ment is used to release the rubber sheet from the wings: the instrument is inserted into the rectangular holes of the clamp, and the rubber dam is directed underneath the clamp (. Fig.  7.33i, j). The most anterior perforation is  

a

b

c

d

e

f

7

..      Fig. 7.33  Sequence to assemble the clamp onto the rubber dam and subsequent placement of the whole set into the mouth. a–c Fitting the clamp into the corresponding orifice for the anchor tooth by placing the rubber under the wings; d view of the clamp wings from the opposite side; e lubrication of the rubber dam on the side to be in contact with the teeth; f fitting the forceps into the round orifices of the clamp; g positioning the clamp on the anchor tooth while bringing the whole set onto the mouth; h view of the clamp on anchor tooth with the rubber above the wings; i the rubber dam is moved underneath the clamp’s wings using a bold instrument; j view

of the rubber dam with good seal around the anchor tooth; k the rubber is then passed over the most mesial tooth included in the perforations; l thereafter, the rubber is passed between the remaining teeth with help of dental floss, which is at the same time used to invert the rubber into the crevice on the approximal surfaces; m if necessary, the dental floss can be passed again in the same interproximal space to push the rubber through; the double strand of floss is then removed from the facial embrasure; n the rubber dam is also inverted on the remaining dental surfaces using a bold instrument and air stream; o rubber dam isolation finished

243 Isolation of the Operating Field

g

h

i

j

k

l

m

n

..      Fig. 7.33 (continued)

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Placement of the Dam and Frame Set Over a Pre-­ positioned Clamp

o

This technique is used with wingless clamps, which cannot be attached to the rubber sheet. In this case, it is essential that the rubber sheet is not too thick and well-lubricated. The clamp must be previously placed on the anchor tooth. Afterwards, the lubricated rubber dam attached to the frame is taken in the mouth, and the most distal perforation is pushed over the clamp using the fingertips [6]. Then, the remaining teeth are passed over their corresponding perforations (. Fig. 7.34a–c).  

Placement of the Dam and Wingless Clamp Followed by the Frame

7

..      Fig. 7.33 (continued)

In this technique, after choosing the correct clamp (. Fig.  7.35a), the bow of the wingless clamp must pass through the most distal perforation in the rubber dam (. Fig.  7.35b). The open clamp with the attached rubber sheet is placed on the anchor tooth using the forceps, usually held in the one hand (. Fig. 7.35c). Generally, the other hand is used to pull the rubber dam out of the way, so the field is visible for placement of the clamp on the tooth (. Fig.  7.35d). Afterwards, the frame is positioned (. Fig.  7.35e). The rubber perforation around the anchor tooth is stretched and passed completely over the clamp (. Fig.  7.35f). In sequence, the remaining teeth are passed over their corresponding perforations, following the same steps previously described [6, 8].  

 

then passed through the most anterior tooth included in the isolated field (. Fig. 7.33k) and stabilized using a piece of elastic, stabilizing cord, ligature, or alternatively a piece of the rubber sheet. The remaining perforations on the rubber are then passed through the remaining teeth, one by one, with the help of fingers, dental floss, and the bold instrument (. Fig. 7.33l). If the interproximal contacts are very tight, it may be necessary to repeatedly use the dental floss until the rubber dam is successfully passed through the interproximal contacts. In this case, it is recommended to work with the dental floss always from the surface of the tooth towards the edge of the perforation on the rubber dam, instead of pushing the rubber between two perforations  – the latter increases the risk of tearing the rubber dam.  

 

Tip

If the interproximal contacts are too tight and multiple passings of the dental floss are needed, a larger piece of floss can be used to direct the rubber dam between the teeth. After the first half of the dental floss has passed between the teeth, it is left in position, and the second half is pushed through the contacts. The double strand of dental floss is then removed towards the facial side of the tooth (. Fig. 7.33m), thus reducing the risk of tearing the rubber.  

 

 

 

 

7.2.8.5

 lacement of the Clamp over P the Rubber Dam

This technique is generally performed when the rubber dam is used to restore class V cavities or non-carious cervical lesions using the gingival retractor clamp no. 212. This clamp is wingless and large, and therefore the techniques described previously do not apply. Therefore, the dam is first attached to the frame. The perforation on the rubber dam is pushed towards the cervical area of the selected tooth until the preparation margins are visible (. Fig. 7.36a). Clamp no. 212, engaged in the forceps, is brought over the rubber dam; the most apical jaw is carefully placed to retract the gingival tissue, so the margins are completely exposed (. Fig. 7.36b). In this technique, care must be taken not to not compress the gingiva lingually while moving the clamp facially nor damage the enamel or the cement on the cervical region. The clamp jaw must be placed about 0.5–1 mm below the gingival cavosurface angle (. Fig. 7.36c) [8]. In cases of cervical lesions with large gingival extension, clamp no. 212M should be used instead (. Fig.  7.14b). This technique is more easily performed four-handed. Placing the clamp over the rubber dam can also be used in posterior teeth if the dentist is working with assistance. In that case, the punched rubber dam is placed over the tooth and held in place by the dental assistant, while the dentist places the clamp. A disadvantage of this technique when working in the posterior region is the reduced visibility [8].  

 

 

 

After the dam is in place, the edges of the perforation must be inverted into the gingival crevice. A bold hand instrument aided by air-blowing is used for this task (. Fig. 7.33n). This step is very important to secure adequate isolation of the operating field when using the rubber dam; otherwise leakage will occur (. Fig. 7.33o).  

 

245 Isolation of the Operating Field

7.2.8.6

Inverting the Rubber Dam Edges

The perforation edges of the rubber dam must be inverted into the gingival crevice of all isolated teeth, [6] to obtain an effective seal and avoid contamination with saliva, blood, or a

crevicular fluid (. Fig. 7.37a, b). On the interproximal area, the rubber dam must be inverted towards the interproximal papilla using dental floss. After moving the floss gingivally, it should be removed facially or lingually, not occlusally  

b

c

..      Fig. 7.34  Placing the rubber dam and frame set over a pre-­positioned clamp. a Placing the clamp; b passing the most distal perforation over the bow of the clamp; c the remaining perforations are passed over their corresponding teeth

a

..      Fig. 7.35  Sequence for placement the rubber dam over the clamp, without the frame. a Testing the clamp, which is then removed; b passing the rubber dam over the bow of the clamp outside of the

b

mouth; c fitting the forceps into the round orifices of the clamp; d placement of the dam and clamp on the tooth; e assembling the dam on the frame; f passing the rubber dam completely over the clamp

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c

d

e

f

..      Fig. 7.35 (continued)

(. Fig.  7.33m). On the facial and lingual surfaces, a bold instrument must be used to direct the rubber sheet inside the crevice simultaneously with an air stream on the tooth, which will dry the surfaces and direct the dam into the gingival crevice (. Fig. 7.38a, b).  

 

7.2.8.7

Removing the Rubber Dam

After the end of the restorative procedure, the clamp must be carefully removed from the tooth. The rubber sheet is then stretched, and the rubber in the interproximal area is carefully cut (. Fig.  7.39). The underlying soft tissue must be protected by the dentist’s fingers, and care must be taken not to cut the lips of the patient, which sometimes are exposed on the perforations when the rubber dam is stretched. After the rubber dam is removed, it must be inspected to verify if there are missing pieces of rubber. The interproximal spaces shall also be inspected with a dental floss. The gingiva surrounding the clamped anchor tooth should be massaged to stimulate blood circulation on the areas of compression.  

7.2.9 

Modified Techniques for Isolation in Special Clinical Situations

If placing rubber dam is needed next to abutment teeth of a fixed prosthesis or work needs to be done on the abutment teeth, the technique is modified accordingly [6, 10].

Other special situations include the placement of rubber dam to include teeth with fixed orthodontic retainers or yet drying the operating field around deep subgingival margins or gingival retractions. In such situations, it may not be possible to place a clamp or trespass the rubber dam individually around the teeth nor retract the gingival tissues. Thus, the easier and most used approach when the use of rubber dam is desired in such clinical situations is the use of the sleeve technique. Here, the rubber dam is not perforated but instead cut in an arch to include several teeth. For the sleeve technique, a clamp is placed in the most distal anchor tooth to stabilize the rubber dam, and the rubber is folded towards the gingiva (. Fig. 7.40). In anterior areas, the use of clamp may be unnecessary, but instead the rubber dam can be stabilized using elastic ligatures. The use of the sleeve technique is beneficial in special situations, for example, if the rubber dam must be used in the area of bridges or orthodontic retainers. Additionally, the sleeve technique may be advantageous when the use of conventional rubber perforations may not result in a satisfactory solution. . Figure 7.41 shows a veneer tooth preparation on central incisor, in which proper positioning of the rubber dam was not achieved with the regular technique. In this case, the sleeve technique was applied to expose the gingival margin of the preparation to allow the restoration with composite. The sleeve technique can be beneficial for adhesive  

 

247 Isolation of the Operating Field

a

b

c

..      Fig. 7.36  Sequence for placement of the clamp over the rubber dam. a Fitting the punched dam over the tooth; b fitting the clamp no. 212, retracting the gingiva on the labial surface and exposing the gingival cavosurface angle of the preparation; c isolation finished

..      Fig. 7.37 Schematic drawings showing the importance of inverting the rubber dam into the crevice. a Flow of the gingival fluid and the saliva through the rubber dam perforation; b by inverting the edge of the rubber dam inside the gingival crevice, the passage of fluids is blocked

a

restorative procedures in teeth with deep subgingival margins or located at areas of gingival retraction, particularly if the gingiva is thin. Although the sleeve technique offers better moisture control of the operating field and retraction of the soft tis-

b

sues than the use of cotton rolls combined with suction, there is a possibility of salivary flow into the operating field. That must nevertheless be controlled and is more problematic when working on the lower jaw due to accumulation of saliva. . Figure 7.42 shows a clinical case of a patient with  

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a

7

b

..      Fig. 7.38  Inversion of the rubber dam into the crevice using a bold instrument and air stream. a The instrument is used to push the rubber towards the crevice while air-blowing; b rubber dam edges were inverted inside the crevice

a light-cured gingival barrier, to completely seal the margins of the rubber dam. Tip

When using the sleeve technique, applying light-cured gingival barriers at the margins of the rubber dam can protects the gingiva and may help to improve the seal (. Fig. 7.42).  

..      Fig. 7.39  Removal of the dam is easier by cutting the rubber whilst protecting the patient’s soft tissues from the scissors

>> Attention must be given when the clamp is placed cervically on resin composite or ceramic crowns or veneers, due to the possibility of edge fractures of the material.

7.2.10 

 ealing Leakage on the Rubber S Dam Isolation

Sometimes, small undesired flaws in the rubber dam isolation may compromise seal (. Fig. 7.43). Commonly encountered flaws may result from inadequate punching of the rubber sheet, e.g., if the distance between perforations is too small, which adversely affect the correct protection of the papilla and inversion of the rubber dam into the crevice (. Fig. 7.44a–c). Some of these flaws can be sealed with success using flexible light-cured resin-based gingival barriers, although this is not always the case.  

 

..      Fig. 7.40  Example of a sleeve dam technique, where the rubber is cut to include several teeth under the opening. The sleeve dam offers retraction of the soft tissues and is here stabilized by placing clamps on the most distally teeth

orthodontic retainer on the lingual surface of lower incisors, which impairs the regular application of the rubber dam. In this case, the sleeve technique was associated with

7.3

 sing Cotton Rolls Combined U with Suction

The use of cotton rolls combined with suction aims to control the moisture of the operating field and displace the surrounding soft tissues around the teeth, such as the lips, cheeks, and tongue. It is difficult to reach complete moisture control during the operative procedures, and because

249 Isolation of the Operating Field

a

..      Fig. 7.41  a Conventional isolation did not allow visualization of the preparation margins on the central incisor, and concern existed that the use of a gingival retraction clamp could further compromise

a

b

the gingival contour. b the rubber dam was removed and replaced as a sleeve dam, where access to the whole preparation margin was granted

b

..      Fig. 7.42  Conventional isolation of the upper arch combined with sleeve dam isolation of the lower arch, due to the presence of an orthodontic retainer on the lingual surface of the lower incisors.

Pieces of rubber are used to stabilize the dam instead of using clamps. a gingival barrier was applied to protect the gingiva; b the gingival barrier is in place and a cotton roll is used on the lingual opening

..      Fig. 7.43  An undesired perforation in the rubber dam compromises seal and allows flow of saliva into the operatorative field (arrow)

this technique does not hinder the involuntary movement of the soft tissues, it must be used with caution, during short periods of time and preferably in four-­handed work [5]. In favorable cases, it can adequately substitute the need for rubber dam isolation [17]. Although the use of cotton rolls can be relatively effective in controlling the moisture, it does not reduce the risks of contaminations and accidents [16]. The use of cotton rolls combined with suction in operative dentistry are indicated in the following situations [11]: 55 When rubber dam isolation is impossible or impairs the aesthetic evaluation of the operating field 55 In patients with nasal obstruction or mouth breathing 55 When rubber dam isolation has failed 55 In teeth that are partially erupted or misaligned and placing the clamp or other retainer is not possible

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a

7

b

c

..      Fig. 7.44  Sealing flaws on the rubber dam is sometimes possible using light-cured gingival barriers. a Failure on the isolation exposing of the gingival papilla; b application of the gingival barrier; c light-cured gingival barrier in position

55 In patients who are allergic to latex, if latex-free sheets are not available 55 For topical fluoride application 55 In cases of temporary restorations 55 For direct veneers or large restorations on anterior teeth. Here, the use of cotton rolls and suction allows a better overview of the operating field and improved visualization of the relationship between the teeth and the gingival level 55 For multiple cervical lesions. Here several teeth can be restored at once, while the rubber dam limits restoring two teeth at a time Cotton rolls shall obstruct the exit of the salivary glands’ ducts (. Fig. 7.45a–c) to reduce the moisture in the oral cavity. . Figure 7.46 illustrates the path of the saliva inside of the oral cavity.  

 

7.3.1 

 aliva Ejector and High-Volume S Evacuators

sues. Disposable saliva ejectors that have a flexible metallic rod are preferred, as they can be curved and adapted in several places of the oral cavity (. Fig. 7.47a). Careful placement of the saliva ejectors is necessary to avoid suction, trauma, or ulceration of the soft tissues on the cheeks or oral cavity floor. Modified saliva ejectors with thin tips exist, and they can be inserted inside the tooth preparation or be used for suction of gels applied over the tooth surface. Some saliva ejectors are anatomically designed to adapt to the mouth at the same time as it retracts the tissues and provides suction. Hygoformic saliva ejectors are curved, adjustable plastic devices which are equipped with five small holes (. Fig.  7.47b, left side). They are placed in the floor of the lower jaw, can reach the most posterior teeth, and push the tongue aside from the working field (. Fig.  7.48a, b). Another very useful saliva ejector also offers tongue retraction (. Fig. 7.47b, right side). It has an anatomic design that can keep the tongue away. It is only found in one size but can fit all patients due to the good flexibility of the plastic. High-volume evacuators (HVE), i.e., larger diameter plastic suction tips with beveled end, collect the water spray as the tooth is being rinsed or prepared (. Fig. 7.49a, b). HVE are capable of quickly removing higher volumes of liquids as well as small solid residues from the operating field and are ideal for four-handed work. HVE are very useful when  

 

 

 

 

Saliva ejectors are devices used to remove saliva and water that comes from the high-speed handpiece [14]. Saliva ejectors are usually made in soft plastic not to hurt the soft tis-

7

251 Isolation of the Operating Field

a

b

c

..      Fig. 7.45  a Exit of parotid gland duct at the parotid papilla, which lies between the first and second upper molars. b Ducts of submandibular and sublingual glands exit in the sublingual caruncles. c Visible saliva drops from minor salivary glands, which are scattered all over the mouth

removing amalgam restorations, thus minimizing the amount of amalgam residues to be swallowed by the patient. Tongue and cheek retraction dam (ex. Ez-Dam dry isolation field) is another technology regarding saliva ejection: it is equipped with high volume suction, tongue retractor, cheek retractor, and biting block all in one device (. Fig. 7.50a, b). The biting block is made of silicone and is available in five different sizes.  

Tip

Hygoformic saliva ejectors shall be placed on the same side of the jaw as you work. It can preferably be adjusted by bending the coil so it pushes the tongue further away from the teeth. These ejectors can be stabilized to the lower jaw by curving it around the chin of the patient.

7.3.2 

Cotton Rolls and Absorbent Pads

The cotton rolls must be highly absorbent of saliva (. Fig. 7.51a). Long cotton rolls are used to isolate one hemiarch (. Fig. 7.51b). Cotton rolls must always be used together with the saliva ejectors and shall be carefully replaced when they become saturated. At the end of the procedure and  

..      Fig. 7.46  Schematics of the saliva path inside the oral cavity. On the right side, the saliva flow comes from the parotid gland, and on the left side the flow comes from the submandibular and sublingual glands

 

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a

7

..      Fig. 7.47  a Examples of disposable saliva ejectors for regular and high-suction evacuation; the transparent tubes can be curved for adaptation in the oral cavity. b Hygoformic saliva ejectors, which are

a

b

more delicate to the surrounding soft tissues; the one on the right of the image also retracts the tongue (ex. Sweflex saliva ejector)

b

..      Fig. 7.48  a Hygoformic saliva ejector in the mouth. b in combination with cotton roll to control moisture of the operating field

a

b

..      Fig. 7.49  a High-volume evacuator combined with hygoformic saliva ejector and cotton rolls in the mouth. b High-volume evacuator used in combination with rubber dam

253 Isolation of the Operating Field

a

b

..      Fig. 7.50  a Tongue and cheek retraction dam is connected directly to the suction unit. b Small perforations in the silicone allow suction of saliva while simultaneously retracting the tongue and cheek

a

b

c

d

..      Fig.7.51  a Examples of cotton rolls of different thicknesses; b long cotton rolls with an internal metallic rod to allow curving (Roeko); c absorbing paper rolls (ex. Septembar Group); d saliva absorbing pads

to be adhered to the mucosa on the exits of the parotid glands. Some pads have a reflexive external side (ex. NeoDrys)

before removing the cotton rolls, it is important to check if they are dry. In this case, they must be moistened with water before removal to avoid undesired damage of the mucosal epithelium. There are also absorbent rolls made of paper and

covered by a layer of non-­woven fabric (TNT), with an identical shape as the cotton rolls (. Fig. 7.51c). There are advantages of not sticking to the oral mucosa of the patient even when they are dry.  

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a

b

c

d

e

f

..      Fig. 7.52  Examples of soft tissue retractors. a Lip and cheek retractor (ex. J. Morita); b labial retractor for procedures on anterior teeth (ex. Indusbello); c labial retractor with protecting rubber (ex. Optragate – Ivoclair/Vivadent); d tongue retractor (ex. Villevie); e cheek

and tongue retractor (ex. Arcflex – FGM); f cheek and tongue retractor combined with saliva ejector (ex. Nola Dry Field System – Great Lakes Orthodontics)

Absorbent pads adhere onto the cheeks’ mucosa, blocking the exit of the parotid gland duct. Such absorbent pads tend to retain more water than cotton rolls. They are made of cellulose or filled with acrylate polymers that retain the moisture and transform it in a gel (. Fig. 7.51d). The absorbent pads must also be moistened before their removal from the oral cavity.

7.3.3 

 

Cheek and Tongue Retractors

The cheek retractor protects cheeks and lips while increasing the visual field (. Fig. 7.52a–c). Before using these retractors, it is necessary to lubricate the patient’s lips with lip balm to avoid drying and lip fissures when the tissue is stretched. There are  

7

255 Isolation of the Operating Field

a

b

..      Fig. 7.53  a Biting blocks with a central orifice to tie dental floss; b biting block in the mouth

also flexible retractors made of rubber, which retract the lips and cheeks evenly and gently (. Fig. 7.52c). The tongue retractor in the form of a disposable bite block restrains the tongue and provides bilateral support (. Fig.  7.52d). Some cheek retractors can be attached to a tongue retractor (. Fig. 7.52e). The cheek and tongue retractor combined with saliva ejector is shown in . Fig. 7.52f; besides retracting the lips and cheeks, it presents a tongue guard and tubes that aspirate saliva. Biting blocks made of silicone can be used to keep the mouth open in patients with difficulties or opening limitations (. Fig.  7.53a). The biting blocks have multiple slots along the lateral surfaces to stabilize on the occlusal surfaces of the teeth. The biting blocks must be inserted between antagonist teeth on the opposite hemiarch to the one that will receive treatment: the narrower edge facing the more distal tooth. The more posterior the biting block is placed, the more the mouth will open anteriorly [15]. It is recommended to tie a piece of dental floss on the biting block for safety reasons (. Fig. 7.53b).  

 

 

 

 

 

7.3.4 

Light-Cured Gingival Barriers

The light-cured resin-based gingival barriers are flowable resins with pigments, which are used to protect the gingival tissues (. Fig. 7.54a, b). Even after light-curing, these resins still show certain flexibility, which makes their removal easy (. Fig. 7.54c). The light-cured gingival barriers can be useful to protect the gingiva from in-office bleaching agents, but as mentioned earlier, they can be also used to correct small defects in the rubber dam or in combination with rubber dam in modified applications (. Fig. 7.42a, b).  

 

 

7.3.5 

Gingival Retraction Cords

Flexible cords are inserted into the gingival crevice to retract the gingiva, improve the visualization and access to gingival

margins during tooth preparation and restoration, as well as control gingival fluid or bleeding during the restorative ­procedure. Twisted (cotton thread twisted around itself), braided (where the threads are weaved), and knitted (formed by rings as knitting stitches or chains) cords are available (. Fig. 7.55a), and the choice is determined by the dentist’s preference, even though the knitted and weaved cords are easier to use [18]. The thicknesses of the cord to be used depends on the depth of the gingival crevice (. Fig. 7.55b). The cords must be packed into the crevice with a thin bold instrument or using specific packing instruments (. Fig. 7.55c), some with fine serrations on the working edge to avoid slipping and damaging the gingival tissue. Retraction cords to mechanically retract the gingiva can be impregnated with astringent or vasoconstrictors solutions, which will cause contraction of the gingival tissue, reduce the flow of gingival fluid, and control bleeding. The most commonly used astringent solutions are aluminum chlorite, aluminum sulfate, zinc chlorite, or iron sulfate. These compounds only act locally and rarely cause systemic reactions while promoting adequate hemostasis of the gingival tissues. Epinephrine can also be used, but possible risks are the increase of the cardiac frequency and arterial pressure as well as allergenic potential. When applying cords impregnated with astringent, their use shall be limited to short periods of time, preferably up to 15 min [19]. Since procedures in operative dentistry generally take longer, mechanical retraction is preferred using non-impregnated cords. The thickness of the retraction cord is chosen according to the depth of the crevice and the degree of desired retraction. The cord is cut to size (. Fig.  7.56a, b) and carefully packed into the crevice (. Fig. 7.56c, d). Care must be taken to not create prolonged ischemia of the tissue; if this is the case, the cord must be replaced by a thinner one. As packing of the cord progresses, part of the cord already inserted into the gingival crevice tends to be displaced as the instrument moves forward. Therefore, the instrument shall return a little and press the previous region again, repositioning the cord.  

 

 

 

 

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a

7

b

c

..      Fig. 7.54  a Light-cured gingival barrier being applied; b after curing; c removal of the gingival barrier

The gingival retraction can cause discomfort to the patient and may lead to permanent gingival retraction. To avoid these problems, the technique must be performed correctly, without excessive pressure during insertion of the cord in the crevice. >> At end of the restorative procedure, the cord must be carefully removed from inside the gingival crevice with the aid of an exploratory probe.

glands (. Fig. 7.58a). When the labial frenulum is small, a single long cotton roll can be placed on the vestibule region (. Fig. 7.58b).  

 

7.3.6.3

Maxillary Posterior Teeth

The cotton rolls must be positioned on the bottom of the vestibule on the posterior region, blocking the exit of saliva from the parotid gland’s duct and retracting the cheek (. Fig. 7.59a). Absorbing pads can also be used; they adhere to the cheek mucosa and absorb the saliva (. Fig. 7.59b). Some absorbing pads have a reflective surface that improves light distribution inside the oral cavity. The saliva ejector must be kept at the floor of the mouth or at the area behind the last molar [14].  

 

7.3.6 

Cotton Roll Isolation Technique

7.3.6.1

Maxillary Anterior Teeth

Two cotton rolls must be placed on the bottom of the vestibule on each side of the labial frenulum to better accommodate it and to avoid their displacement (. Fig.  7.57a). On patients that have a small labial frenulum, a single long cotton roll can be used on the whole arch (. Fig. 7.57b).  

 

7.3.6.2

Mandibular Anterior Teeth

Two cotton rolls must be placed on the bottom of the vestibule, one on each side of the lower lip frenulum. Two additional cotton rolls must be placed on each side of the lingual frenulum. These block the exit of the submandibular and sublingual glands, as well as the exits of minor salivary

7.3.6.4

Mandibular Posterior Teeth

It is the region that requires most care and attention when using cotton rolls and suction, due to the large quantity of saliva and the movement of the tongue, lips, and cheeks. A cotton roll must be placed over the exit of the parotid gland’s duct in the upper vestibule. Another cotton roll must be paced in the lower vestibule, beside the tooth to be treated, and one or two more cotton rolls shall be placed on the floor of the mouth, under the tongue. This ensures that saliva is absorbed at the same time that the tongue is displaced (. Fig. 7.60a). It is important to remember that the saliva ejectors must be placed at all times  – during the  

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257 Isolation of the Operating Field

restorative procedure  – in the oral cavity, removing the saliva and maintaining the cotton rolls in position. Alternatively, a long cotton roll can be placed on the upper and lower vestibule (. Fig. 7.60b) or the cotton roll can be combined with absorbing pads, always under constant suction (. Fig. 7.60c).

Tip

When you want to remove the cotton rolls or absorbant pads, make sure that they are wet. Otherwise they adhere to the mucosa and can wound the epithelium.

 

 

b

a

c

..      Fig. 7.55  a Examples of gingival retraction cords (1, twisted; 2, braided; and 3, knitted); b cords with varying thicknesses; c instruments used for placement of the retraction cords into the gingival crevice

a

b

..      Fig. 7.56  Placement of gingival retraction cord. a Initial situation; b retraction cord cut to size and brought to the cervical region of the tooth; c packing the cord into the crevice with a special packing instrument of round tip (ex. Millennium); d gingival retraction finished

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c

7

d

..      Fig. 7.56 (continued)

a

b

..      Fig. 7.57  Cotton roll isolation of the area of maxillary anterior teeth. a Two cotton rolls placed on each side of the upper labial frenulum; b single, long roll placed on the upper arch vestibule

a

..      Fig. 7.58  Cotton roll isolation of the area adjacent to the mandibular anterior teeth. a Cotton rolls are placed beside the lower labial frenulum. Cotton rolls placed on the lingual side are stabilized by

b

the saliva ejector; b pre-curved, long cotton rolls placed over the lower arch vestibule and under the tongue

259 Isolation of the Operating Field

a

b

..      Fig. 7.59  a Cotton roll isolation of the area adjacent to the maxillary posterior teeth; b saliva-absorbing pad positioned onto the cheek mucosa

a

b

c

..      Fig. 7.60  Cotton roll isolation of the area of mandibular posterior teeth. a Cotton rolls positioned on the lower vestibule, under the tongue and over the exit of the parotid duct; b pre-curved, long cotton

roll positioned over the exit of the parotid duct and in the lower vestibule; c cotton roll combined with absorbing pad (red arrow) and hygoformic saliva ejector (blue arrow)

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Tip

After acid etching and rinsing of the surface during an adhesive technique, you need to change the cotton rolls or absorbant pads in order to avoid moisture reaching the operating field. If the cotton rolls are contaminated with adhesive or resin-based materials, these must be changed to avoid contact of unpolymerized material with the patient’s soft tissues.

Conclusion

7

Controlling moisture and contamination in the operating field offer the best conditions for optimal restorative work. The use of rubber dam is preferred for effective control of moisture and preventing contamination, both essential prerequisites for adhesive dentistry. If the use of rubber dam is not possible, the next best available option is the use of cotton rolls combined with suction. This chapter explains the importance of isolation of the operating field to enhance the quality of the restorative procedures. The necessary instruments and consumables for providing effective moisture control, either by using rubber dam or combining cotton rolls with suction, have been revised. The techniques for obtaining moisture control of the operating field have been thoroughly explained.

References 1. Wang Y, Li C, Yuan H, Wong MCM, Zou J, Shi Z, Zhou X. Rubber dam isolation for restorative treatment in dental patients. Cochrane Database Syst Rev. 2016;9:CD009858. 2. Keys W, Carson SJ.  Rubber dam may increase the survival time of dental restorations. Evid Based Dent. 2017;18(1):19–20. 3. Browet S, Gerdolle D. Precision and security in restorative dentistry: the synergy of isolation and magnification. Int J Esthet Dent. 2017;12(2):172–85.

4. Mahn E, Rousson V, Heintze S.  Meta-analysis of the influence of bonding parameters on the clinical outcome of tooth-colored cervical restorations. J Adhes Dent. 2015;17(5):391–403. 5. Gilmore HW, Lund MR, Bales CD, Vernetti S, editors. The operating field. Operative dentistry. 3rd ed. St. Louis: CV Mosby Company; 1977. p. 100–16. 6. Summitt JB. Field isolation. In: Summitt JB, Robbins JW, Schwarz RS, editors. Fundamentals of operative dentistry. Illinois: Quintessence Books; 1996. p. 109–39. 7. Barrancos Mooney J, Rodríguez GA.  Isolamento do campo operatório. In: Barrancos Mooney J, editor. Operatória Dental. Buenos Aires: Medica Panamericana; 1999. p. 395–438. 8. Wilder AD.  Preliminary considerations for operative dentistry. In: Roberson TM, Heymann HO, Swift EJ, editors. Sturdevant’s art and science of operative dentistry. St. Louis: Mosby/Elsevier; 2006. p. 447–91. 9. Besek M.  Optidam, the new dimensional rubber dam. Available from: http://www.­kerrhawe.­com/products/documents/Article_ Besek_en.­pdf. 10. Baum L, Phillips RW, Lund MR, editors. Isolation of the working field. Textbook of operative dentistry. Philadelphia: WB Saunders Company; 1995. p. 187–219. 11. Conceição EN, Soares CG. Isolamento do campo operatório. In: Conceição EN, Colaboradores, editors. Dentística: Saúde e Estética. Porto Alegre: Artes Médicas Sul; 2000. p. 83–94. 12. Mondelli J. Fundamentos da Dentística Operatória. São Paulo: Santos; 2006. 13. Luz MA. Isolamento do campo operatório. In: Garone Neto N, editor. Introdução à Dentística Restauradora. São Paulo: Santos; 2003. p. 25–41. 14. Souza JB, Fernandes MI, Filho AV, Taveira WS, Rocha LI, Gonçalves AM. Isolamento do Campo Operatório. In: Busato AG, editor. Grupo Brasileiro dos Professores de Dentística. São Paulo: Santos; 2005. p. 203–36. 15. Marzouk MA, Simonton AL, Gross RD, editors. Controle do Campo Operatório. Dentística Operatória: Teoria e Prática Moderna. Santos: São Paulo; 1987. p. 95–118. 16. Iorio PA, editor. Isolamento do campo operatório. Dentística Clínica: Adesiva e Estética. Santos: São Paulo; 1999. p. 3–19. 17. Brunthaler A, König F, Lucas T, Sperr W, Schedle A.  Longevity of direct resin composite restorations in posterior teeth. Clin Oral Investig. 2003;7:63–70. 18. Donovan TE, Chee WW. Current concepts in gingival displacement. Dent Clin North Am. 2004;48(vi):433–44. 19. Reiman MB. Exposure of subgingival margins by nonsurgical gingival displacement. J Prosthet Dent. 1976;36:649–54.

261

Matrix and Wedge Systems Cesar Rogério Pucci, Carlos Rocha Gomes Torres, and Ali Ibrahim Abdalla 8.1

Introduction – 262

8.2

Matrix – 263

8.2.1 8.2.2

 etallic Matrix – 263 M Transparent Plastic Matrix – 268

8.3

Matrix Retainer – 270

8.4

Wedges – 276

8.4.1 8.4.2

F requent Mistakes Related to the Use of Wedges – 279 Elastic Wedges – 280

8.5

Challenges for the Correct Use of Matrix and Wedges – 281

8.6

Custom-Made Matrices – 283

8.6.1 8.6.2 8.6.3 8.6.4 8.6.5

S pot-Welded and Riveted Matrix – 284 Window Matrix – 285 Barton Matrix – 285 T- band Matrix – 285 S-shaped Matrix – 285

References – 288

© Springer Nature Switzerland AG 2020 C. R. G. Torres (ed.), Modern Operative Dentistry, Textbooks in Contemporary Dentistry, https://doi.org/10.1007/978-3-030-31772-0_8

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Learning Objectives The learning objectives of this chapter are related to the following topics: 55 To explain the definitions, characteristics, and importance of the matrix and wedge use during restorative procedures 55 To present the different kinds of metallic and plastic matrices (circumferential and sectional) 55 To explain the use of different matrix retainers in detail, followed by its indications and techniques of use 55 To present the frequent mistakes related to the use of wedges and the solution for challenging situations 55 To explain the technique to prepare custom-made matrices, including spot-welded and riveted matrix, window matrix, Barton’s matrix, T-band matrix, and S-shaped matrix

8

8.1

Introduction

There are several reasons that can lead to the loss of tooth structures, such as the caries disease, traumas, attrition, occlusal overload, erosive tooth wear, among others. Regardless of the cause, the restorations of those lost structures must recover the lost shape, function, and esthetics using an artificial restorative material. Those materials present plastic viscosity so that they can be applied into the cavity and be shaped, before they undergo some kind of curing reaction and become hard, maintaining the shape created and restoring the lost tooth surfaces. In some situations, such as on the occlusal surfaces of the posterior teeth (Class I) or on the facial or lingual surfaces of the posterior and  anterior teeth (Class V), the tooth preparations present surrounding walls that will hold the restorative material in place, simplifying the procedure (. Fig. 8.1a). However, in the cases where the lesion, and consequently the preparation, reached the interproximal surfaces, it is impossible to guarantee the perfect restoration of the lost surface if the material is inserted directly into the preparation,

because it will flow into and invade the interproximal space and facial and lingual embrasures. To solve this technical problem, it is necessary something be used as a temporary artificial holder for the restorative material until its setting, allowing that the contour and smoothness of the proximal surface are restored (. Fig. 8.1b – arrow). This device, called matrix, is basically a strip or band made of metallic or plastic material that works as a type of a tray, inside which the restoration will be made. The use of a matrix to restore teeth was introduced in Dentistry by Dr. Louis Jack, in 1871. In order to keep the matrix in position around the tooth structures during the restorative procedure, several different types of instrument can be used, commonly called matrix retainer. When the matrix is placed in position on the interproximal region, it must be stabilized and better adapted to the remaining tooth structure. To reach this goal, a small wedge with triangular cross section is inserted into the interproximal space (. Fig.  8.1b  – asterisk). The set of the three components is known as the matrix and wedge system, which have the following goals: [3, 4, 6]. 55 To allow the application or condensation of the restorative material inside the cavity 55 To hold the restorative material until it passes through the setting reaction and keep the desired shape 55 To allow the anatomic and physiological reconstruction of the teeth 55 To allow the restoration of the interproximal contact 55 To allow the sculpture of the restoration 55 To prevent the restorative material extrusion at the cavosurface margin, resulting in excess at the margins (flash) or overhangs in the cervical region, which would result in the presence of and deposit of bacterial biofilm 55 To help the isolation of the prepared tooth, once it will help to keep the rubber dam in position and retract the gingiva  

 

 

a

..      Fig. 8.1  Indications of a matrix system. a The preparations surrounded by vertical walls are capable to hold the restorative material. b When the proximal surface was lost, it is necessary a temporary

The matrices and wedge system can be used in cavities that involve proximal surfaces, such as Class II, III, and IV according to Black classification, or even on the Class I compound

b

holder during the restorative procedure (the  arrow indicates the matrix band; the wedge can be seen in the interproximal space)

263 Matrix and Wedge Systems

preparation, where the matrix will aid the restoration of the buccal groove on the mandibular molars or lingual groove on the maxillary molars. Occasionally, the matrices can also be used for Class V restorations. >> The correct application of a wedge can prevent the restorative material extrusion at the cavosurface margin, which would create overhangs in the cervical region, promoting biofilm deposition and periodontal inflammation.

8.2

Matrix

In order to a matrix band has an adequate performance, some basic requirements must be present. In the first place, they must be very thin, so they do not take too much space in the interproximal area, but at the same time be capable to resist the pressures applied over the restorative material, as it occurs during the amalgam condensation. They must be flexible, to adapt on the contours of the remaining tooth structure, and smooth to create a restoration with the external surface roughness like the remaining tooth structure. In addition, they must be rigid enough to not suffer deformation during the use and be compatible with the restorative material, not sticking to it [6]. The matrices can be classified on several manners, which will allow to understand better its purpose. In relation to the involvement of the dental crown, they can be classified in the circumferential matrix, which involves the mesial, distal, facial, and lingual surfaces simultaneously, or partial (also called sectional), which involves only one of the proximal surfaces (. Fig. 8.2a, b). In relation to the restorative material used, the matrices can also be classified in matrices for silver amalgam and matrices for esthetic materials, as composite resins or glass ionomer cement. On the anterior teeth, the matrices for esthetic materials need to be transparent to allow the passage of the light from the light-curing unit through it. In relation to the way of use, the matrices can be called universal, when  

a

they are ready-made and can be used in several different situations, or custom-made, when the dentist makes by hand a specific matrix for a special clinical situation [5]. The matrices can also be made of metal, used for posterior teeth, or plastic that can be used for anterior and posterior teeth. It is important to emphasize that the matrix band must never be used more than once. When the band is used again, there is an increase of the surface roughness and change of the contour due to the deformation, which will significantly jeopardize the smoothness and desired profile of the proximal surface to be restored [1]. 8.2.1

Metallic Matrix

Several types of metallic matrices are available on the market, and they can be circumferential or sectional. They can be used on posterior teeth, both for amalgam and composite restorations, once the light for the curing is applied occlusally.

Circumferential Metallic Matrix

8.2.1.1

The most commonly used metallic matrices are the straight bands. They are flat bands available in two thicknesses, 0.03  mm (0.0015 inch) or 0.05  mm (0.002 inch), and two heights, 5 mm indicated for teeth with shorter clinical crowns and 7  mm indicated for longer crowns (. Fig.  8.3a). They need to be cut on the necessary size to wrap the crown and to be fixated onto the matrix retainer, resulting in a cylindrical shape (. Fig. 8.3b). There are also the metallic bands with a V or boomerang shape, known as Tofflemire matrix band. They are 7 cm long with various widths for different crowns sizes. Some of them present projections in the internal border that serve to adapt onto the preparations where the gingival walls go far down into the cervical region (. Fig.  8.3c). The boomerang-­shaped matrix must be assembled on the retainer with the internal edge of its curvature facing the cervical region. This will result on a funnel-shaped cone when wrapped around a tooth, placed with its smaller diameter facing the cervical area, contributing for a better adaptation  

 

 

b

..      Fig. 8.2  Classification of the matrices, according to the surrounding of the crown. a Circumferential; b sectional

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a

b

c

d

8

..      Fig. 8.3  Metallic circumferential matrix bands used with the matrix retainer. a Straight strips. b straight strip assembled on the matrix retainer. c Tofflemire matrix. d Tofflemire matrix assembled on the retainer

of the matrix (. Fig. 8.3d). It is also available pre-contoured Tofflemire circumferential matrix, which follows the natural contour of the proximal tooth surface. Some metallic bands present an integrated retainer system that dismisses the use of a separated matrix retainer. They can have disposable retainers integrated with the bands or be retainerless. The applications of the retainerless circumferential matrices are particularly interesting in the cases where the tooth, which will be restored, is also the anchor tooth and will receive the clamp for isolation. Some examples can be observed in . Figs. 8.4, 8.5, and 8.6.  

 

8.2.1.2

Sectional Metallic Matrix

The sectional matrices surround only one proximal surface during the restoration, which present some advantages. As the matrix band has a certain thickness that occupies a space between the restorative material and the adjacent tooth, to get a proper interproximal contact, the wedge must separate the adjacent teeth with enough distance to compensate the thickness of the band. On the cases of a Class II cavity that involves only one proximal surface, when using a circumferential matrix, the separation produced by the wedge must compensate twice the thickness of the matrix. On the other hand, using a sectional matrix the need of teeth separation is smaller. The sectional matrices can be prepared cutting a piece of the straight band with a length enough to involve the proxi-

mal surface and go further in about 1/3 of the mesiodistal dimensions of the crown, in the buccal and lingual surfaces. The corners of the matrix that will be facing the gingiva must be cut, avoiding that it damages the soft tissues (. Fig. 8.7a). Then, it is burnished over a paper mixing pad to become curved as the proximal surface (. Fig. 8.7b, c). After that, it is placed and wedged, being burnished in position to improve the contact with the proximal surface of the adjacent tooth (. Fig.  8.7d, e). After that, a piece of green low fusion compound is handled as shown in . Fig. 12.16a–i and applied on the buccal and lingual embrasures to avoid the extrusion of the restorative material (. Fig.  8.7f). At the moment of compound application, the matrix must be pressed toward the contact with the adjacent tooth with the back of a spoon or a burnisher. This technique was proposed by Sweeney, in 1942, and it is a type of custom-made matrix [5, 6, 8]. The compound can be replaced by a light-cured gingival barrier. In 1986, Alvin Meyer projected and produced sectional matrices that were ready to be used, with pre-contoured surfaces, simplifying the anatomic reconstruction of the proximal surface. They have a different occluso-gingival height, adapting to different crown sizes. They also present models with extensions in the internal edge for cavities with a large cervical extension (. Fig.  8.8a). Analyzing it sideways, they have a concave and a convex edge  

 

 

 

 

 

8

265 Matrix and Wedge Systems

a

b

c

d

..      Fig. 8.4  a Retainerless circumferential matrix bands with a built-in tensioning ring (TDV). b Matrix in position. c The pinched aluminum built-in tensioning ring acts as a retainer for better adaption around the tooth. d Ring folded to not harm the soft tissues or the cheek

a

b

..      Fig. 8.5  a Retainerless circumferential matrix bands (AutoMatrix, Dentsply), available in multiple heights and gauges for varied clinical solutions. A device is available in the set for tightening the matrix

around the tooth (Automate Tightening Device) as well as a snipper for removal. b AutoMatrix in place

(. Fig.  8.8a  – arrow). They also have a concave side that must face the tooth preparation and a convex side that faces the adjacent tooth (. Fig. 8.8b). First of all, the occluso-gingival height of the sectional matrix is chosen, and it must be compatible with the depth of the cavity. With a clinical tweezer, it is placed into the interproximal region, observing that the concave side of the

matrix must be in contact with the adjacent tooth (. Fig. 8.8c). The convex edge is placed toward the cervical area. After that, a wedge is placed, and then, using a clamp forceps, a separation ring is placed to bring the borders of the matrix in contact with the tooth surface in the embrasure area (. Fig. 8.8e). This hinders what the restorative material extrudes, and it promotes the additional dental separation, simplifying to

 

 

 

 

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a

8

..      Fig. 8.6  a Disposable circumferential matrix band and retainer (Omni-Matrix, Ultradent), with different sizes identified by the color of the conical handle. The pivoting head allows the retainer to be turned

b

to any side, depending on the tooth to be restored. b Omni-Matrix in position

a

b

c

d

..      Fig. 8.7  Technique for the preparation of custom-made sectional matrix. a Sectioning a piece of the matrix band. b Burnishing over a paper mixing pad for contouring. c Contoured matrix. d Matrix in position and wedge application. e Burnishing of the matrix toward the

contact with the adjacent tooth. f Application of the of low fusion compound in the embrasures to improve the adaptation and prevent flash formation

267 Matrix and Wedge Systems

e

f

..      Fig. 8.7 (continued)

a

b

c

d

..      Fig. 8.8  a Pre-contoured sectional matrices with different dimensions (the arrows point to the edges). b Lateral view of the matrix showing the concave side. c Matrix taken in place by a dental tweezer. d Different types of separation rings (1, unimatrix, TDV; 2,

Palodent, Darway). e Separation rings being positioned using a clamp forceps. The wedge was already placed (Curvy – Voco). f Set in position

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e

f

..      Fig. 8.8 (continued)

8

obtain proper proximal contacts during composite restoration. The separation rings are based on the principle of the McKean master separator ring, developed for more than 50 years ago. The separation rings may have different configurations. Some present tines with a round cross section, whereas others present a flat rectangular cross section (. Fig. 8.8d). In some cases, the tines with a round cross section may allow a better adaptation of the matrices in the embrasure areas, but they cannot be used in preparation where the proximal boxes present a large buccolingual dimension (. Fig. 15.9g, h). However, the rings with a rectangular cross section can be used in those situations. The separation rings must be placed over the wedges, touching the proximal surface of the adjacent tooth in the embrasure areas, providing an adequate separation and more predictable contacts on posterior composites (. Fig. 8.8f). There are on the market several variations, based on the idea of the sectional matrices with the separation ring, that present some advantages in relation to the regular systems presented. However, the basic principles are the same. As examples, we have the V Ring® (Triodent), Composi-Tight 3D® (Garrison), Hawe Adapt® (Kerr Hawe), etc. The TriClip® system (Triodent) presents the matrix and the ring attached in a one set and an elastic wedge integrated, simplifying the process to use it. In . Fig.  8.9a–d, it can be observed the Composi-Tight 3D® system, which has two kinds of separation rings. The larger ring is for most premolars and molars, and the smaller one is for short or badly positioned teeth. The larger ring has notches on its tines which allows the passage of the wedge through it and also has soft silicon faces that rest on the proximal surfaces of the adjacent teeth in the embrasures, pressing the matrix and better adapting to the surface, reducing the possibility to have composite flash at this area. The presence of those soft faces allows its adaptation even on preparation with large proximal boxes, where a regular separation ring would not be used, because it would penetrate the preparation through the embrasure. The matrices in this system have a very thin layer of a nonstick material, which hinders the composite bond to the matrix.  

8.2.1.3

Metallic Cervical Matrix

They are matrices to restore the facial and lingual cervical areas of teeth in Class V preparations using a chemical curing material, such as conventional glass ionomer cements or self-­ curing composites. They are available in several sizes, adapting on different tooth morphologies. They have a concave and a convex side. Nowadays, its use is reduced due to the dentist’s preference for light-curing materials on those types of restorations (. Fig. 8.10a, b).  

 

 

 

8.2.2

Transparent Plastic Matrix

The clear plastic matrices have the advantage to allow the passage of the light through them and are recommended for composite restorations, where there is the need to apply light through the matrix. They are always used in restorations on anterior teeth and may be optionally used on composite restorations of posterior teeth, since the light is applied from the occlusal surface and not through the matrix. They should never be used for amalgam restorations, since they are not capable to resist the condensation forces. They are made of polyester, cellulose acetate, or polyvinyl chloride (PVC) and can be straight or pre-contoured, circumferential, or sectional. There are also special matrices shaped as the region that will be reconstructed, such as the entire crowns or the cervical region. 8.2.2.1

Circumferential Plastic Matrix

The most commonly used plastic matrix is the straight polyester strip or “Mylar” strip. Mylar® is generally used to describe polyester films, although it is a trademark owned by DuPont company. It is flat and transparent strip used on the restoration of anterior teeth (. Fig. 8.11). It has the inconvenience of not presenting the natural curvature of the proximal surface of the teeth. To restore the anterior teeth, this deficiency is easily overcome by the use of the wedge and a careful restorative technique (. Fig. 8.11b). However, if used for restorations of the posterior teeth associated to a matrix retainer, it will produce a flat proximal surface, incompatible with the original anatomy.  

 

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a

b

c

d

..      Fig. 8.9  Composi-Tight 3D® matrix system (Garison). a On the left a ring with soft silicon faces to improve the adaptation of the matrix and on the right the ring for short or badly positioned teeth. b Sectional

a

matrices in several shapes covered with a nonstick material. c Ring in position. d The cervical slot can be observed, which allows the passage of the wedge

b

..      Fig. 8.10  Metallic pre-contoured cervical matrix (Hawe Neos Dental). a Different shapes. b Side view showing the concavities on one of the sides

To be used on posterior teeth, some manufactures created pre-contoured polyester strips, as it can be seen in . Fig. 8.12a, b. Some require the use of the matrix retainer, whereas others are retainerless. The use of the transparent matrices on posterior teeth was proposed based on the theory that composite resin shrinks toward the light. Therefore, to improve the marginal  

sealing of the composite restoration in the gingival wall, it would be necessary that the light was applied initially on this region, passing through the matrix. Nowadays, it is known that the composite shrinks toward the bonded cavity walls, despite the light direction [9]. Therefore, the use of clear plastic matrices for the composite restoration of posterior teeth has drasti-

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a

b

..      Fig. 8.11  a Straight polyester strips; b clinical use

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a

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..      Fig. 8.12  Pre-contoured polyester strips for posterior teeth. a To use with matrix retainer (premolar strips – TDV); b retainerless (TDV)

cally been reduced, because they are thicker and more difficult to take into position, when there is remaining of the interproximal contact, and cannot the burnished. 8.2.2.2

Special Plastic Matrices

Some plastic matrices present the shapes and sizes of the tooth surface that will be reconstructed. As examples, there are the cellulose acetate or PVC transparent plastic crowns forms (or transparent strip crowns), as seen in . Fig. 8.13a, b. They are used as a shell matrix for the restoration or teeth reshaping, simplifying the sculpture process. The set of crowns presents several sizes to adapt to most teeth crowns. The most adequate is chosen, according to the mesiodistal dimensions and the inciso-cervical height, and then fitted by cutting the excess with scissors. Another type of special plastic matrix is the cervical matrix for light-curing materials (. Fig. 8.14a, b). They can be used for composite resin  or  modified glass ionomer cement restorations, and it is especially indicated to the last one, due to its viscous and sticky consistency. The technique for use of this matrix can be seen in . Fig. 14.44a–l.  

 

 

8.3

Matrix Retainer

They are devices intended to hold the matrix in position and to adjust it around the tooth that will be restored, allowing a correct contour to be obtained, hindering the extrusion of the material into the buccal and lingual embrasures and on the gingival margin. They can be used with metallic or plastic strips. There are several types on the market, even though the most popular are the Tofflemire, Ivory, and Siqveland [5, 7]. The most commonly used is the Tofflemire matrix retainer, developed by Joseph Benjamin Franklin Tofflemire, also called “universal” retainer. It has two different models, depending on the angulation of the guide posts of the head, which has guide channels where the matrix is adapted (. Fig. 8.15) [6]. The model with guide posts at a 90° angle with the long axis of the instrument should be used buccally, while the model with the guide posts contra-angled can be used lingually when the preparation extends to the buccal surface. This type of retainer has the advantage of being easily separated from the band in an occlusal direction, avoiding, for example, the fracture of the recently condensed amalgam  

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a

b

..      Fig. 8.13  a Polyvinyl chloride transparent strip crowns; b clinical use for reshaping of the peg-shaped lateral incisors

a

b

..      Fig. 8.14  Cervical matrix. a Hand instrument with clear cervical matrix attached to the tips (TDV); b cervical matrix to be attached to the tip of the light-curing devices (TDV)

LOCKING VISE

KNURLED INNER NUT KNURLED OUTER NUTS

SCREW

GUIDE CHANNELS DIAGONAL SLOT

..      Fig. 8.15  Tofflemire Matrix retainer types. (1) Straight. (2) Contra-angled. The differences are indicated by the arrows

restoration, because this material takes longer to reach the final crystallization and its maximum strength [5, 6]. . Figure  8.16 presents the different parts of the instrument. On one of the ends is the head of the retainer, with the U-shaped guide posts and the guide channels, where the  

FRAME

..      Fig. 8.16  Nomenclature of the parts of Tofflemire retainer

band must go through and then be positioned on the diagonal slot of the locking vise. On the other end are the knurled outer and inner nuts, which tighten or loose the matrix from the retainer and increase or decrease the band circumference, respectively. The frame holds all the components and guides the movement of the locking vise.

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To assemble the matrix band on the Tofflemire retainer, the dentist must first verify the diameter of the tooth that will be restored. When the band is bought in rolls, it must be cut in a way to surround the entire tooth, leaving a small portion that will be attached to the locking vise. In general, about 7 cm of the matrix band is enough. Some matrix bands are sold already cut on the final dimensions, such as the Tofflemire matrix, which facilitates the use. The retainer must be prepared to

receive the band, turning the inner knurled nut (larger) counterclockwise until the locking vise is about 5  mm from the head of the retainer. Holding the inner nut, the vise locking screw must be unscrewed, turning the outer knurled nut (smaller) counterclockwise until the pointed spindle is free of the diagonal slot. The dentist folds the band end to end to form a loop (. Fig. 8.17a), passing through the correct guide channel (. Fig. 8.17b), attaching the band inside the diagonal slot  

 

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..      Fig. 8.17  Assembling of band on the Tofflemire matrix retainer. a Folding the band end to end to form a loop. b passing the band through the correct guide channel, attaching it inside the diagonal slot of the vise. c the outer knurled nut is turned clockwise to tighten the pointed spindle toward the band. d–f options to assemble the band

into the guide channels. g the inner knurled nut is turned clockwise, adjusting the matrix to the diameter of the crown, tightening it. h correct positioning of the retainer with the slotted side of the head directed gingivally. i incorrect positioning with the slotted side of the head occlusally

273 Matrix and Wedge Systems

g

h

i

..      Fig. 8.17 (continued)

of the vise. Then, the outer knurled nut is turned clockwise to tighten the pointed spindle against the band (. Fig.  8.17c). The choices of which guide channel will be used depend on the tooth that will be restored. In general, the retainer is placed buccally with its long axis parallel to the teeth arch. However, its position (right, left, or parallel) can vary according to the convenience of each situation (. Fig.  8.17d–f). The matrix band assembled in the retainer is placed around the tooth, and the inner knurled nut is turned clockwise, adjusting the matrix to the diameter of the crown, tightening it (. Fig. 8.17g). The matrix retainer must be positioned on the arch with the slotted side of the head directed gingivally, to permit easy separation of the retainer from the band occlusally (. Fig. 8.17h). After finishing the restoration, the retainer removal is made turning the outer knurled nut counterclockwise to release the band, pulling the retainer toward the occlusal surface, with the matrix remaining in position. If the retainer is placed upside down, with the slotted side of the head occlusally, its removal before the matrix band will be more difficult (. Fig. 8.17l).  

 

 

 

 

In . Fig. 8.18a, b, the Ivory No. 8 matrix retainer can be observed. It works like Tofflemire retainer, with a difference that there is only one guide channel. It also presents a locking vise, a locking screw, and inner and outer knurled nuts. This type of retainer also allows the removal of the retainer before the matrix, by loosen the fixation outer nut. Another type of popular matrix retainer is the Siqveland, also known as Steele’s Siqveland retainer (. Fig.  8.19a). By the fact that it does not have a fixation nut, the matrix must be folded on a specific sequence so that it is assembled, according to what can be observed in . Fig. 8.19a–l, and it is necessary about 10  cm of the matrix band. It presents as advantages the swivel locks, which can be turned from one side or another, improving the adaptation of the matrix in the cervical region of tapered teeth (. Fig. 8.19b, l). As a disadvantage, there is the fact that it is not possible to separate the matrix from the retainer before its removal from the tooth structure, unless the band is cut, which is a difficult procedure to be made inside the mouth.  

 

 

 

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..      Fig. 8.18  Ivory No. 8 matrix retainer. a View of the instrument in different angles. b Matrix retainer assembled in position

8 a

b

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..      Fig. 8.19  a Siqveland matrix retainer from different views. b Options to adjust the swivel lock for adaptation of the band on the cervical region. c–j steps to assemble the band. k matrix properly assembled. l cervical adjustment by the correct positioning of the swivel lock

275 Matrix and Wedge Systems

e

f

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h

i

j

k

l

..      Fig. 8.19 (continued)

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8.4

8

Wedges

The wedges are pieces of wood, plastic, or elastic material introduced into the interproximal space, between the matrix and the proximal surface of the adjacent tooth, over the interdental gingival papilla, to guarantee the correct restoration of the proximal surface. Among the functions of the wedges, the following ones must be highlighted: 55 Helps to stabilize the matrix band 55 Aids on the restoration of the adequate contour of the lost surface, because it approaches the matrix to the remaining tooth structure on the cervical region of the proximal surface 55 Prevent the extrusion of the restorative material in the gingival margin of the preparation 55 Aids to retract the rubber dam and the interdental gingival papilla 55 Promotes separation between the adjacent teeth to compensate the thickness of the matrix band

first and second maxillary molars, where the buccal embrasure is larger. However, if the tooth presents some rotation, each case in particular must be evaluated, analyzing the embrasures by looking at them from the occlusal point of view, checking which one is the largest. The wedges must be taken into position with a forceps that can produce a firm grasp, such as the mosquito forceps, preferable with a curved end to ease the access. The dental tweezer does not allow the necessary grasp to firmly insert the wedge into its position. Preferably, the wedges must be used associated with the rubber dam isolation of the operating field. Otherwise, it can fall into the oral cavity and be aspirate or swallowed. >> The interproximal space has a triangular shape, with the apex toward the contact point and the base toward the gingival tissue. Therefore, the wedge should also present a triangular cross section, being named anatomic wedges. Tip

Wedges are pieces of wood, plastic, or elastic material introduced into the interproximal space, between the matrix and the proximal surface of the adjacent tooth, to guarantee the correct restoration of the proximal surface.

The wedges are inserted through the larger embrasure, once they have a convergence toward the tip. The attempt to insert the wedge from the smaller embrasure will hinder its complete penetration into the interproximal space.

When made of a rigid material, it must have the exact shape of the interproximal space as it can be observed in . Fig. 8.20a. The interproximal space has a triangular shape, with the apex toward the contact point and the base toward the gingival tissue. Therefore, the wedge must also present a triangular cross section, being named anatomic wedges (. Fig. 8.20b). The wedges are inserted through the larger embrasure, once they have a convergence toward the tip. The attempt to insert the wedge from the smaller embrasure will hinder its complete penetration into the interproximal space. On teeth that are properly positioned on the arches, the lingual embrasures are generally the largest ones, with exception between the

To restore a proximal surface of a tooth, a matrix band is placed between the teeth, and then the restorative material is applied. As the matrix occupies some space due to its thickness, in case no wedge is used, when the matrix is removed the space occupied by it will remain opened, resulting on food impaction (. Fig. 8.21a–c). When a wedge is placed between the matrix and the adjacent tooth, before the application of the restorative material, besides preventing the extrusion of the material into the cervical region, it promotes the tooth separation to compensate for the thickness of the matrix band (. Fig. 8.22a, b – arrows). The wedges must be positioned in such way that it is held on the tooth surface below the cavosurface gingival angle, effectively

 

 

a

 

 

b

..      Fig. 8.20  Correct shape of the anatomic wooden wedge. a Shape of the interproximal space – asterisk; b shape of the anatomic wedge

277 Matrix and Wedge Systems

a

b

c

..      Fig. 8.21  Importance of the space occupied by the matrix on the restoration of the proximal contact. a Preparation done removing the contact with the adjacent tooth. b placement of the matrix without

a

wedge. c restoration performed failing to recreate the interproximal contact due to the space occupied by the matrix

b

..      Fig. 8.22  Use of the anatomic wedge. a Dental separation to compensate the thickness of the matrix; b proximal contact reestablished

pressing the adjacent tooth without deforming the matrix. When the matrix and the wedge are removed, the teeth come back to the normal position, and the contact is recovered. The regular wedges can be made of wood or plastic material. The wooden wedges present the advantage that when they become wet, absorb a little water and expand, adapting firmly into the interproximal space. Some manufacturer offers on the market roughly finished anatomic wooden

wedges in a set like a “comb.” They need to be removed and finished with an abrasive disc before used, adjusting its size to the space between the teeth (. Fig. 8.23a, b). When finishing the wedges, it is important that after the procedure, it presents a gradual convergence toward the end, ensuring that all interproximal space will be filled. The wedge must be inserted under pressure between the teeth. Therefore, it should not be so thin that it would not be able to separate the  

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b

..      Fig. 8.23  a Roughly finished anatomic wooden wedges supplied as a “comb”; b finishing of the wedge with an abrasive disc

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a

b

c

..      Fig. 8.24  Types of wedges. a Finished wooden wedges. b transparent and opaque plastic wedges. c curved wedges (Curvy – Voco)

teeth and may fracture. In addition, and it should not have just a very short convergent tip, as a spear, which would not be capable to penetrate the space between the teeth. Other manufacturers produce finished individual wedges, identified by colors according to its several sizes (. Fig. 8.24a). The plastic wedge is made in opaque or transparent material (. Fig.  8.24b). The clear wedges, also  named reflective wedges, were developed to be used in association with clear matrix bands, to conduct light to the cervical region of the proximal surface, on the attempt to direct the polymerization  

 

shrinkage vectors toward this region. However, several studies have proved that this does not occur, making this technique each time less used. The plastic wedges are generally  straight and anatomically shaped, similar to the wooden wedges, with a triangular cross section. However, some manufacturers offer curved wedges that also follow the contour of the bone crest and the proximal surface of the teeth, improving the adaptation of the matrix onto the tooth (. Fig. 8.24c). The colors indicate if they are recommended to restore the mesial or distal sur 

279 Matrix and Wedge Systems

 requent Mistakes Related to the Use F of Wedges

faces, and they can be thinner or thicker, depending on the size of the interproximal space.

8.4.1

>> The wedge must separate the adjacent teeth enough to compensate the thickness of the matrix band. It has to be inserted under pressure into the interproximal space. Therefore, it should not be so thin that it would not be able to separate the teeth and may fracture. In addition, it should not have just a very short convergent tip, as a spear, which would not be capable to penetrate between the teeth.

When using a rigid anatomic wedge, several mistakes can be done that will seriously compromise the proximal contour of the restoration, and consequently the health of the periodontal tissue. The most common mistake is to insert the wedge upside down into the interproximal space (. Fig. 8.25a). On this position, the wedge will deform the matrix, resulting in a concave proximal contour instead of a convex one, besides not being able to seal correctly the gingival margin, allowing  

a

b

c

d

e

f

..      Fig. 8.25  Mistakes during the application of wedges. a Inverted wedge. b wedge above the gingival margin. c wedge with a very large upper edge. d very high wedge. e very small and loose wedge.

f rubber dam penetration inside the preparation. The arrows indicate the extrusion of the restorative material or defects of the restoration contour

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b

..      Fig. 8.26  The use of a very short wedge. a Results on a wrong proximal contour b

8

the extrusion of the material producing overhangs. That will result in bacterial biofilm growing, gingival inflammation, and secondary caries lesions. Another very common mistake is to place the wedge above the cavosurface gingival angle (. Fig. 8.25b). Besides hindering the separating effect of the wedge, it will deform the matrix and the proximal contour of the restoration, other than allowing the extrusion of the material and formation of overhangs. The wedges with the upper edge too large will also result on the concave proximal contour of the restoration (. Fig. 8.25c). If a wedge, besides having a very large edge, is also very high in occluso-gingival direction, the matrix will remain far from the proximal surface of the adjacent tooth, and an open contact may also occur (. Fig. 8.25d). The wedges must be inserted into the interproximal space in such way that they enter under pressure and remain tight in position. If the wedge is smaller than the necessary, remaining  loose between the teeth, it will  not produce the necessary teeth separation, which  allow the extrusion of restorative material into the gingival sulcus and occurence of overhangs (. Fig. 8.25e). Another mistake that may happen is the remaining of rubber dam or gingival tissue inside the gingival wall of the preparation, after the placement of the matrix and the wedge. On those cases, after the application of the restorative material and isolation removal, the space occupied by the dam or gingiva will remain empty, allowing the growing of bacterial biofilm, postoperative tooth sensitivity, and secondary carious lesions (. Fig. 8.25f). On the other hand, the use of very small wedges in occluso-gingival dimensions, even though they are tight between the teeth, may result in the formation of a very large contact area on the occluso-gingival direction, when the material is applied, specially in the case of the amalgam, that is condensed under pressure, reducing the spaces for the gingival papilla and the col (. Fig. 8.26a, b). Another very serious mistake occurs when the matrix is not taken beyond the gingival cavosurface angle over the proximal tooth surface, and the wedge is applied, pressing the matrix inside the preparation. This will result, besides an inadequate proximal con 

 

 

 

 

 

..      Fig. 8.27  Matrix and wedge positioned inside the preparation

tour, in the presence of part of the gingival wall exposed to the oral cavity, causing postoperative sensitivity and resulting in bacterial biofilm growing, gingival inflammation, and carious lesion (. Fig. 8.27). In . Fig.  8.28a–d, there are radiographic images of the restorations performed without the correct placement of the wedges, resulting in overhangs and inadequate proximal contours.  

 

8.4.2

Elastic Wedges

The elastic wedges were developed to adapt to the proximal surfaces, promoting a correct positioning of the matrix and the tooth separation (. Fig. 8.29a–c). To be positioned, after matrix placement, it must be stretched with a clamp forceps and taken in place (. Fig.  8.29b, c). They present different thicknesses, indicated by colors, depending on the size of the interproximal space (. Fig. 8.29a). It has advantages to easily adapt to the different anatomic contours of the proximal surface. They present small holes on the central region that allow, when stretched, to become thin enough to be posi 

 

 

281 Matrix and Wedge Systems

a

b

c

d

..      Fig. 8.28  a–d Restorative material overhang on the cervical region and the inadequate proximal contours (arrows)

tioned on the cervical region. They act simultaneously on the buccal and lingual surfaces, by the presence of the rubber handles. To remove them, one end must be pulled with forceps to cut the wedge on the central part. 8.5

 hallenges for the Correct Use of Matrix C and Wedges

One of the challenging situations to the correct adaptation of the matrix on the region of the gingival wall happens in some MOD preparations, where one of the gingival walls is located more cervically than the others. Taking into account that the band must touch the proximal tooth surface, beyond the cavosurface gingival angle of the preparation, what happens is that when the matrix is applied, it will firstly touch the gingival tissue and sometimes the bone crest on the side where the cavity is shallower, hindering the matrix to go further cervically on the side where the cavity is deeper, leaving a gap between the matrix and the cavosurface angle (. Fig.  8.30a). This happens because the more the carious lesion or the restoration goes further cervically, the greater can be the bone resorption on this area, resulting in a bone unevenness, i.e., the bone crest is higher on the side where  

the cavity is shallower and lower on the side where the cavity is deeper. To solve this problem, the matrix band must be assembled on the matrix retainer and taken in position. The exact position of the deepest box must be observed and the matrix removed from the tooth. All the cervical contour of the matrix, except the area that corresponds to the deepest box, is cut with scissors, and the matrix is replaced (. Fig. 8.30b–d). Then, the wedges are applied and the restoration can be properly made [6].  

Tip

In case of MOD preparations with too different depth and uneven bone crests, the band can be cut on the side of the shallower preparation, allowing a deeper matrix penetration on the opposite side, corresponding to the deepest cavity.

Other challenging situations occur on the mesial surface of the first maxillary premolar. At this place, there is an anatomical peculiarity, where the root bifurcation produces a fluted (concave) area on the proximal surface. Different cross

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a

b

c

8

..      Fig. 8.29  a Elastic wedges (Elastic wedge – Danville). b Use of the forceps to stretch the wedge. c Elastic wedge in position associated to a sectional matrix and separation ring

sections of this kind of tooth is presented in . Fig. 8.31a, b, allowing to better visualize this concavity, showing that it increases cervically. The more cervically located is the gingival wall of the preparation, the more the existing concavity hinders the adequate adaptation of the matrix and wedge on the cavosurface margin. That creates a gap between the matrix and the proximal tooth surface, allowing the extrusion of the restorative material and overhangs (. Fig.  8.32a). To solve this problem, two options are presented. The first is to use a small cotton ball between the anatomical wedge and the matrix band, which would press the band toward the external tooth surface, closing the gingival margin (. Fig. 8.32b–e) [6]. For that, the wedge is placed on the entrance of embrasure, but before inserting it completely into the interproximal space, the small cotton ball is positioned between it and the proximal surface of the tooth. When the wedge is completely inserted, the cotton is forced toward the concave area, pushing the matrix and sealing the cervical region (. Fig. 8.32e). Other technique, known as wedge wedging, consist in using an oblique wedge on the lingual side, preferably a toothpick with round cross section or even a small anatomic wedge, which is inserted between the matrix band and the wedge already placed. The oblique wedge will press the matrix band toward the tooth, closing the gap (. Fig. 8.32f) [2, 6].  

Tip

On the mesial surface of first upper premolar, an anatomical concavity can hinder the proper adaptation of the matrix to the cavosurface angle. In order to improve the band contact with the margin, a small cotton ball or an oblique toothpick can be placed between the wedge and the matrix.

 

 

 

 

When the space between the adjacent teeth is too wide and a single wedge is not enough to fill the area, or when the proximal box is wide in the buccolingual dimensions, the double wedging technique can be applied. On this technique, one wedge is inserted from buccal embrasures and another from the lingual, side by side. A melted compound or light-­cured gingival barrier can be applied to stabilize the wedges. In the case of shallow proximal box associated with gingival recession, the wedge will remain significantly apical to the gingival margin, not properly sealing the matrix.  In this case, the piggyback wedging technique can be used. For that, one larger wedge is inserted as normally used, while another smaller wedge (piggyback) is applied above the first one, providing a good adaptation and contour for the matrix.

283 Matrix and Wedge Systems

a

b

c

d

..      Fig. 8.30  Proximal boxes with different depths in MOD preparations. a The applied matrix is not capable to reach the gingival margin on the deepest box, due to touching gingival tissue on the shallower

a

side. b cutting of the band preserving the area corresponding to the deepest box. c matrix ready to use. d matrix properly positioned

b

..      Fig. 8.31  a Concavity on the mesial surface of the maxillary first premolar. b Cross sections of the crown showing the concavity on the mesial surface which becomes deeper gingivally

8.6

Custom-Made Matrices

In some specific situations, the uses of universal or regular matrices supplied by the manufacturers do not allow the correct reconstruction of the lost tooth structure. Therefore, the dentist needs to prepare the special hand-

made matrices, which are named  individual, anatomic, or custom-made. One kind of custom-made matrix is the sectional Sweeney matrix for Class II restorations, which was already presented in . Fig. 8.7a–f. Other types will be described next, with their indications and specifications.  

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..      Fig. 8.32  Techniques to allow a correct adaptation of the matrix to the mesial surface of the maxillary first premolars. a Use of a wedge with a conventional shape resulting on a lack of adaptation of the gingival cavosurface angle. b insertion of a small cotton “ball” with the

8.6.1

Spot-Welded and Riveted Matrix

When restoring the proximal surfaces of posterior teeth, the straight matrix band attached to the matrix retainer solves most of the cases. However, in some situations, such as on cases where the tooth to be restored is also the anchor tooth with the clamp, or when the clamp in the neighbor tooth

wedge. c cotton ball being inserted. d, e cotton in position allowing the correct adaptation of the matrix. f Technique of the oblique wedge inserted lingually

touch the matrix retainer/band set, hindering its correct cervical adaptation, the use of the universal matrix is contraindicated. In addition, on the cases of large preparation, involving one or more lost cusps, the tensile on the band created by the matrix retainer makes the matrix penetrate the preparation, hindering the correct anatomic shape restoration. On those cases, the custom-made retainerless spot-­

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surfaces, due to its inclination toward the occlusal surface. Therefore, a small piece of the matrix is placed on the exact region of the buccal or lingual box, which will be pressed toward the tooth surface using a wooden wedge. Details about the preparation of this matrix can be found in . Fig. 11.14a–u.  

8.6.4

..      Fig. 8.33  Welding the matrix

welded or riveted matrices can be used. To make it, a piece of the straight band is cut and then positioned around the tooth, drawn taut with flat-nosed pliers or mosquito forceps, after which the band is removed. The demarcated matrix circumference can be fastened with a spot-welding device, generally used for the building up orthodontic bands, which create a welded joint (. Fig. 8.33). Another option to fasten the matrix is to use a No. 141 riveting plier as presented in . Fig. 12.15.  

 

T- band Matrix

The T-band matrix can be obtained already shaped from the manufactures or be prepared by the dentist. The prefabricated band is made of brass or stainless steel and can be straight or curved. It has two flanges on one tip, which gives its T-shape (. Fig.  8.34). The flanges are folded forming a U-shaped path. The free end of the band is slipped through the U formation. The flanges are closed, and the free end is bent or curled to produce a circle and surround the tooth circumferentially. The T-band matrix can also be hand made by the dentist, using a straight band, as can be observed in . Fig.  8.35a–i. For that, about 6 cm of the matrix strip is used. In one of its ends, the corners are cut creating a spear-shaped (. Fig. 8.35a). Then, a smaller piece of band is cut, with about 1.3 cm, and placed on the flat end of the already cut band, creating a T-shape (. Fig.  8.35b). The ends of the smaller band are folded, to adapt to the longer strip (. Fig.  8.35c). The flat end of the longer strip is folded with the aid of a tweezer (. Fig.  8.35d) and the smaller strip slide under it (. Fig.  8.35e). Then, the matrix is turned upside down (. Fig. 8.35f), and the spear-shaped end is pulled and passes between the smaller and the larger bands, on the opposite side of the folds (. Fig. 8.35f, g). The matrix is placed around the tooth, and the spear end is pulled, adapting to the tooth contour. Then, it is folded fastening the final position (. Fig.  8.35h, i). This type of retainerless matrix presents similar indications to the spot-welded and riveted matrix, with the advantage that it can be prepared in advance, without the patient on the chair.  

 

 

 

 

8.6.2

Window Matrix

 

 

On large Class V preparations for amalgam, the direct application of the restorative material is very hard, because when it is condensed in one side of the preparation, it escapes on the other, due to the fact that the cavity is large and the axial wall is convex. To solve this problem, it was proposed the use of a window matrix. It is prepared applying the universal matrix around the tooth, using a matrix retainer on the opposite surface to the one with the preparation, opening a window on the region that corresponds to the preparation, but with smaller dimensions. The material is then applied through the window, allowing to obtain the desired shape of the restoration. Details about this matrix can be found in . Fig. 11.15a–o.

 

 

 

8.6.5

S-shaped Matrix

 

8.6.3

Barton Matrix

On compound Class I preparation, the application of amalgam on the lingual or buccal boxes is very difficult. That is related to the fact that a universal matrix placed around the tooth is not capable to correctly adapt onto those smooth

The S-shaped matrix is indicated for restoration of horizontal slot Class II preparations. In this case, the restorative material must be applied through the buccal or lingual cavity access, contraindicating the use of a matrix retainer. A straight matrix band is shaped like an “S” and applied between the teeth. A wedge with the heated compound is applied on the opposite side of the cavity access. More details about this technique can be seen in . Fig. 11.16.  

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a

b

c

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e

..      Fig. 8.34  a Prefabricated straight T band made of stainless steel or brass (in the middle). b flanges folded forming a U-shaped path. c the free end of the band is slipped through the U formation to produce a

circle. d the flanges are closed. e the matrix is adjusted around the tooth and the free end is bent to lock the matrix

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f

..      Fig. 8.35  a–i Technique for preparation of a custom-made T-band matrix

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h

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..      Fig. 8.35 (continued)

Conclusion This chapter described the definitions, characteristics, and importance of the matrix and wedge use during restorative procedures. The different kinds of metallic and plastic matrices (circumferential and sectional) and  the matrix retainers were explained in detail, followed by its indications and techniques of use. The frequent mistakes related to the use of wedges and the solution for challenging situations were presented. The  various techniques to prepare custom-made matrices were described. The clinician must know all options available and its different indications and advantages, being able to apply the best technique for each clinical situation.

References 1. Anauate Netto C, Fichman DM, Youssef MN. Estudo in vitro da rugosidade superficial e do perfil proximal de amálgamas condensados contra matrizes de aço inoxidável. Rev Odontol da Univ São Paulo [Internet]. 1997;11:173–80. https://doi.org/10.1590/S0103-­06631997000300005.

2. Baratieri LN, Monteiro Junior S, Andrada MA, Ritter AV. Odontologia Restauradora: Fundamentos e Possibilidades. Santos: São Paulo; 2001. 3. Gilmore HW, Lund MR. Operative dentistry. Saint Louis: Mosby; 1973. 4. Horsted-Bindslev P, Mjör IA. Modern concepts in operative dentistry. Copenhaguen: Munksgaard, 1988.  5. Mondelli J, Ishikiriama A, Galan JJ, Navarro MF.  Dentística Operatória. Sarvier: São Paulo; 1976. 6. Roberson TM, Heymann H, Swift EJ. Sturdevant’s art and science of operative dentistry. 5th ed. St. Louis: Mosby; 2006. 7. Summitt JB, Robbins JW.  Amalgam restoration. In: Schwartz RS, Summitt JB, Robbins JW, editors. Fundam oper dent a contemp approach. Illlinois: Quintessence Publishing; 1996. 8. Sweeney JT.  The class V amalgam restoration. J Am Dent Assoc. 1942;29:2140–4. https://doi.org/10.14219/jada.archive.1942.0342. 9. Versluis A, Tantbirojn D, Douglas WH. Do dental composites always shrink toward the light? J Dent Res. 1998; ­https://doi.org/10.1177/0 0220345980770060801.

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Protection of the Dentin-Pulp Complex Adriana Cristina de Mello Torres, Ana Paula Martins Gomes, Claudio Hideki Kubo, and Carlos Rocha Gomes Torres 9.1

Introduction – 291

9.2

Understanding the Dentin-Pulp Complex – 291

9.2.1 9.2.2

 entin – 291 D Pulp – 294

9.3

Defense Mechanisms of the Dentin-Pulp Complex – 295

9.4

Assessment of Pulp Condition – 296

9.4.1 9.4.2 9.4.3 9.4.4

 namnesis – 296 A Extraoral Clinical Exam – 296 Intraoral Clinical Exam – 296 Radiographic Examination – 300

9.5

Diagnostic Hypothesis – 301

9.6

Origins of Pulpal Alterations – 302

9.6.1 9.6.2 9.6.3 9.6.4

 arious Lesion – 302 C Tooth Preparation – 302 Occlusal Trauma – 303 Restorative Procedure – 303

9.7

Factors Affecting the Dentin-Pulp Complex Protection – 304

9.8

Cleaning of the Tooth Preparations – 305

9.8.1 9.8.2

 emineralizing Cleaning Agents – 305 D Non-demineralizing Cleaning Agents – 306

9.9

Protective Materials – 307

9.9.1 9.9.2 9.9.3 9.9.4

 avity Varnish – 308 C Desensitizing Agents – 308 Adhesive Systems – 308 Zinc Oxide-Eugenol Cement – 308

© Springer Nature Switzerland AG 2020 C. R. G. Torres (ed.), Modern Operative Dentistry, Textbooks in Contemporary Dentistry, https://doi.org/10.1007/978-3-030-31772-0_9

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9.9.5 9.9.6 9.9.7 9.9.8

 lass Ionomer Cement – 309 G Calcium Hydroxide – 310 Mineral Trioxide Aggregate (MTA) – 310 Materials Containing Bioactive Molecules – 311

9.10

Techniques for Protection of the Dentin-Pulp Complex – 312

9.10.1 9.10.2

I ndirect Pulp Protection – 312 Direct Pulp Protection – 319

References – 329

291 Protection of the Dentin-Pulp Complex

Learning Objectives The learning objectives of this chapter are related the following topics: 55 The histology and physiology of the dentin-pulp complex 55 Defense mechanisms of the dentin-pulp complex 55 How to perform the assessment of pulp condition and create the diagnostic hypothesis 55 What are the origins of pulpal alterations 55 Factors affecting the dentin-pulp complex protection 55 How to perform the cleaning of the tooth preparations 55 To understand the characteristics of all protective ­materials 55 To perform different techniques for protection of the dentin-­pulp complex

9.1

The great interrelation between the pulpal tissue, represented by the odontoblasts, and the dentin, complicates the separation of the physiopathological phenomena that occurs in one or other tissue. Therefore, the pulp and the dentin form an integrated system that is generally named dentin-­pulp complex. The cut of the dentin tissue actually means the cut of a living tissue, formed by mineralized and cellular parts, represented by the odontoblast process inside the dentin tubules. A minimal intervention on the most external part of the dentin is immediately noticed by the pulpal tissue, and a corresponding response, of local or general magnitude, starts to develop [111].

Introduction

Several factors can produce aggressions to the teeth, such as the carious lesions, trauma, non-carious lesions of erosive tooth wear, abrasions, abfraction, etc. Regardless of the cause, the restoration must recreate the shape, function, and esthetic of the tooth structure, avoiding producing alterations to the biological equilibrium on the pulp tissue. Therefore, the procedures of the tooth preparation must be carefully performed, avoiding overheating or exposure of the pulpal tissue. The restorative material applied must not be an irritation source to the pulp, but it must protect it from the external aggression. This way, the knowledge about the dentin-pulp complex physiology, as well of the materials and restorative techniques, are essential to perform a minimally invasive dentistry, with minimum intervention and a maximal preservation of the tooth structure.

9.2

>> Dentin and pulp are closely connected, in a way that physiopathological responses in one tissue will also affect the other. Therefore, they form an integrated system that is called the dentin-pulp complex.

Understanding the Dentin-Pulp Complex

The structural components of the dentin-pulp  complex are the dentin, composed by the mineralized dentin and the non-mineralized predentin, and the pulp, which is a type of loose connective tissue. The dentin and the pulp have the same embryonic origin, working as a single functional unit [26]. Even though there are differences of structure and composition between the dentin and pulp, those tissues are closely connected, in a way that physiopathological responses in one tissue will also affect the other [26, 107]. The close relation between the dentin and the pulp can be observed since the developing of the dental organ, when the odontoblastic cells from the pulp are responsible for the formation, organization, and maturation of the collagen fiber and proteoglycans for the dentin formation. On the other hand, the beginning of the dentinogenesis determines the differentiation of the dental papilla into pulp [168].

9.2.1  Dentin

The dentin is an avascular mineralized connective tissue. It is composed of approximately 45% of inorganic material (hydroxyapatite and other ions), 30% of organic material (collagen, lipids, glycosaminoglycan, and other substances in smaller quantities), and 25% of water by volume. Its composition varies with the age due to the constant formation of new mineralized tissue, even after the complete tooth formation [108]. The basic structural components of the dentin are the following: The odontoblast with the odontoblast process, the dentin tubule, the periodontoblastic space, the intratubular dentin matrix (peritubular), and the intertubular dentin. The odontoblasts are peripheral cells which are responsible for the formation of the dentin tissue and for the transmission of several stimuli to the pulpal tissue, because they are in direct contact with the pulp. The dentin tubules hold the odontoblast processes and are formed during the dentinogenesis (. Fig.  9.1). The diameter and the volume of the tubule’s lumen vary according to the age of the tooth and the location inside the dentin. The closer the dentin is to the pulp, the greater is the amount and diameter of the dentin tubules (. Fig. 9.2a, b). The periodontoblastic space is located between the tubule wall and the odontoblast process. This space has tissular fluid and some organic components, such as thin collagen fibers. The intratubular dentin is deposited on the tubule walls, and it is characterized by its high mineral content and the lack of the organic components. The intertubular dentin is located between the dentin tubules, around the intratubular dentin [108]. Despite its high degree of mineralization, it is rich in organic matrix composed of collagen fibers surrounded by amorphous substances (. Fig. 6.5) [7]. The tissular fluid present in the pulp is under pressure  due to the blood circulation, and it tends to overflow through the dentin tubules if they are cut, being called dentinal fluid. The intrapulpal pressure, in normal conditions, is  

 

 

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estimated to be 25–30 mmHg, transferring part of this force to the dentinal fluid [66]. Therefore, the dentin has a certain permeability that varies according to some factors, such as the proximity to the pulp, age, and the degree of dentin mineralization [107, 123]. The dentin permeability is proportional to the number and the diameter of the tubules; consequently the deeper the cavity is, the greater it will be [168]. In . Fig.  9.3, there is an extracted tooth in which occlusal surface was ground flat until the dentin is exposed. After that, it was acid etched to open the tubules. As the pulpal chamber follows the external anatomy of the tooth, on the region corresponding to the cusp tips, the pulpal horns are closer to the surface, and the dentin is deeper [112]. The tooth was connected to a device to create a simulated pulpal pressure. After some time, on the areas close to the pulpal horns, it was observed a greater overflow of liquid, showing the higher permeability at this region. The

movement of the dentinal fluid inside the tubules due to the exposure of the dentin by the operative procedures, traumas, caries, and others is called transdentinal permeability or simply dentin permeability [72, 168]. >> The dentin close to the pulpal tissue has tubules with larger diameter, in higher amount, resulting in increased dentin permeability.

 

..      Fig. 9.1  Microphotography of the dentin-pulp complex showing the odontoblasts (black arrow) and the odontoblast process inside the dentin tubules (red arrow). Mallory’s trichrome stain, 400× magnification. (Photography kindly supplied by Prof. Dr. Miguel Angel Castillo Salgado, Professor of Histology, ICT, São José dos Campos – UNESP)

a

Between the mineralized dentin and the odontoblast layer, there is the predentin, a layer of non-mineralized matrix with about 10–20 μm thickness. It is formed by the odontoblasts and consists mostly of collagen fibers and proteoglycan. The predentin exists not only during the dentinogenesis, but also it is found covering the circumpulpar dentin of the teeth with complete rhizogenesis and in function, once there is a continuous and slow deposition of dentin during the entire life of the tooth [108]. The dentin can be classified into three basic types: primary, secondary, and tertiary [89]. The primary dentin is

..      Fig. 9.3  Regions of higher dentin permeability on the deeper areas close to the pulpal horns

b

..      Fig. 9.2  Relation between the diameter and the number of tubules and the proximity of the pulpal chamber. a Superficial dentin with less tubules; b deep dentin with more tubules

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formed mostly before the tooth eruption and presents a regular tubule disposition. The secondary dentin is formed due to the low intensity stimuli, resulting from the normal biological function, during the clinical use of the tooth after its eruption. It presents narrower and slightly sinuous tubules. It is deposited all over the pulpal surface and especially on the roof and on the floor of the pulpal chamber [7]. As a result of the continuous deposition of secondary dentin, the volume of the pulpal chamber is each time smaller with the passing of the years (. Fig. 6.13a, b).  

>> As a result of the continuous deposition of secondary dentin, the volume of the pulpal chamber is reduced with the aging.

odontoblasts, after the death of the original odontoblastic layers due to aggressions suffered by the tooth. The tertiary dentin formed by the pre-existing primary odontoblasts that survives the moderate irritation is called reactionary dentin, while the dentin formed by newly differentiated odontoblastlike cells formed due to the death of the original odontoblasts, from a pulpal progenitor cell, is called reparative dentin [147]. The formation of the tertiary dentin, reactional or reparative, represents a defense mechanism that is important for the dentin-pulp complex (. Fig.  9.4a–c). The interface between the tertiary reparative dentin and the dentin formed by primary odontoblasts is important, once the tubules between both types of dentin do not communicate directly, forming a barrier against the entrance of some aggressive agents in direction to the pulp (. Fig. 9.4c). Inside the dentin tubules, it can be observed the presence of the odontoblastic process responsible for the formation of the dentin matrix, besides the dentinal fluid and, occasionally, amielinic free nerve ending [32]. Every stimulus, no matter if it is mechanical, physical, chemical, or biological, applied on the external surface of the tubule, causes the movement of the dentinal fluid that reflects on the free nerve ending that occasionally penetrates slightly on the dentin  

 

The tertiary dentin is formed when there are pulp irritations, such as caries, tooth preparations, erosion, abrasion, and thermal, mechanical, chemical, or electrical stimulus, among others. It is located on underlying irritation zones and presents scarce, tortuous, or absent dentin tubules [48, 85, 158, 167]. In relation to this point, it is important to make distinctions between the tertiary dentin formed by the primary odontoblasts, and the ones formed by cells differentiated in a

b

c

..      Fig. 9.4  a Presence of tertiary dentin on the region of the pulp chamber roof on tooth with attrition (arrows); b tooth where the defective restoration was removed, showing the presence of the tertiary dentin on the region of the mesiobuccal pulp horn (arrow) exposed during the preparation; c microphotography showing the

difference between the secondary dentin (SD) with regular tubules and the tertiary dentin (TD) with irregular deposition of the matrix and tubules. Mallory’s trichrome stain, 400× magnification. (Microphotography kindly supplied by Prof. Dr. Miguel Angel Castillo Salgado, Professor of Histology, ICT, São José dos Campos – UNESP)

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tubules or on the ones located on the peripheral region of the pulp. This explanation, named  hydrodynamic theory, was stated by Brännstrom and is the most accepted one to explain the dentin sensitivity [66]. 9.2.2  Pulp

The dental pulp can be defined as a highly specialized loose connective tissue, with an ectomesenchymal origin, surrounded by the dentin wall, occupying the pulpal chamber and the root canal. It is directly connected to the circulatory and nervous system through the neurovascular bundle that enters through the apical foramen [65]. The specialization of the pulpal connective tissue is mainly due to cells that are disposed on its periphery, the odontoblasts, which are responsible for the formation of the dentin matrix [53]. The pulp is composed of 25% of organic material and 75% of water. It is basically formed by the following structural elements: progenitor cells (odontoblasts, fibroblasts, and undifferentiated mesenchymal cells or stem cells), defense cells (lymphocytes and macrophages), amorphous interstitial substances (proteoglycans and glycoproteins), and interstitial fibrous substance (collagen fibers) [27]. On the study of the pulp structure, the dental pulp can be divided into two zones: peripheral, composed of the odontoblastic and subodontoblastic layers, and central core, composed mostly by vessels and nerves (. Fig. 9.5). The most external layer of the pulp, called odontoblastic, is formed by the cell bodies of the odontoblasts, located underlying the predentin. The main function of the odontoblasts is the production of dentin [26]. Below the odontoblastic layer, there is the cell-free zone of Weil, rich in blood capillaries, amielinic nerve fiber network (Raschkow plexus), and the cytoplasmic process of the fibroblasts.  

..      Fig. 9.5  Microphotography of the dentin-pulp complex showing the odontoblastic layer (OL), acellular zone of Weil (AZ), cell-rich zone (CZ), and pulp central region (CR). Mallory’s trichrome stain, 200× magnification. (Microphotography kindly supplied by Prof. Dr. Miguel Angel Castillo Salgado, Professor of Histology, ICT, São José dos Campos – UNESP)

Below the cell-free zone, there is a cell-rich zone, composed of fibroblasts, mesenchymal undifferentiated cells (pre-odontoblasts), macrophages, and lymphocytes. When there is the death of the odontoblasts, there is an increase of the mitosis on the cellular zones and the migration of those cells toward the odontoblastic layer, and this is the beginning of the odontoblastic layer recovery process after pulpal damage [168]. This process is possible due to the capacity of the mesenchymal cells to differentiate into odontoblast-like cells and, consequently, to reactivate the reparative capacity of pulp on the injured region [111]. The central core of the pulp has thicker blood vessels and nerves surrounded by connective tissue rich in fibroblasts, as well mesenchymal undifferentiated cells. The arterioles and venules that enter and exit the pulpal cavity through the foramens and the apical ramifications create the rich vascular supply of the dental pulp. Following the track of the blood vessels, there is an abundant nerve supply, originating from the trigeminal nerve. The nervous fibers that enter the pulp are mielinic and mediate the pain sensations caused by the external agents, while the amielinic fibers are associated with the blood vessels, having, among other functions, the vasomotor control. Those fibers are basically classified into two types, according to the location, function, diameter, and speed of nervous impulse conduction: A delta and C fibers. On the peripheral zone, there are the A delta fibers, which are mielinic and thermoreceptors for cold, with high-speed conduction of the nervous impulse and not related to the tissue damage. On the central zone, next to the blood vessels are the C fibers, amielinic, thermoreceptors for heat, with low speed of nervous impulse conduction and related to the tissue damage (inflammatory process). The dental pulp has four basic functions: formative, nutritive, sensory, and defense [47]. The formative function is related to the formation of the dentin during the entire life of the tooth, being the most important one. The nutritive function is related to its rich vascularization, by the entrance of the nutrients and oxygen through the vessels and exit of the tissue metabolic waste. The sensory function is characterized by the capacity of the pulp to respond with pain to different aggressive agents, by means of the mielinic and amielinic nervous fibers. The defense function may be observed when the pulp defends itself from the aggressive stimuli with the formation of sclerotic or tertiary dentin [27]. The dental pulp changes with the time due to the aging physiological process. Those changes include the modification of a young tissue (rich in cells and poor in fibers) to an old tissue (poor in cells and rich in fibers), that is, changes from the loose connective tissue to dense connective tissue. Those changes are important from the clinical point of view, because the defense capability of an old pulp is smaller than the one of a young pulp [108] and the prognostic for keeping of the pulp vitality after the direct protection of the dentin-­ pulp complex may be reduced. Young patients that submitted their teeth to several “aggressive” stimuli (caries, trauma,

295 Protection of the Dentin-Pulp Complex

smoking, among others) throughout their lives may lead to the reduction of the of pulp tissue defense capability by the aging of the connective tissue. >> The dental pulp changes with the time due to the aging physiological process. Those changes are important from the clinical point of view, because the defense capability of an old pulp is smaller than the one of a young pulp, and the prognostic for keeping of the pulp vitality after some dental treatments may be reduced.

9.3

 efense Mechanisms of the Dentin-Pulp D Complex

The dentin-pulp complex can suffer changes when exposed to different types of external aggressors, such as the dental caries, traumas with or without tooth fracture, tooth preparations, attrition, abrasion, erosive tooth wear, restorative materials, orthodontic movement, and acid etching. The dental pulp tries to block those aggressors by means of three defense mechanisms: dentin sclerosis, deposition of tertiary reactionary and/or reparative dentin, and pulpal inflammation. The response of the dentinpulp complex to the aggressors depends basically on the pulpal condition and the maintenance of the pulp vitality. The maintenance of the dentin-pulp complex vitality is essential, because it is responsible for the response to the external stimuli. >> The dental pulp tries to block the aggressors by means of dentin sclerosis, deposition of tertiary dentin, and pulpal inflammation.

Under external aggressions, first, the tissue responds with local tubular sclerosis by deposition of intratubular dentin on the underlying region to the carious lesions, which reduces the diameter of the dentin tubules [16, 47, 107, 157]. Clinically, the tubular sclerosis results in the darkening of dentin color (. Fig. 9.16a, b). The tubular sclerosis is produced by light to moderate irritating agents, such as slow progression carious lesions, moderate trauma after tooth preparation, abrasion, erosion, attrition, and aging. The tubular sclerosis will not happen if the odontoblasts have previously been destroyed. When the aggression is too intense, the odontoblasts die and the corresponding tubules are referred as dead tracts. The second line of defense of the dentin-pulp complex is a deposition of tertiary reactional dentin, with the intention to increase the distance between the aggressor agent and the pulpal tissue [98]. The structure of the deposited dentin matrix depends on the activity of the carious lesion. The more active the lesion is, the more irregular the formed tertiary dentin will be [15]. This tertiary dentin generally presents more sinuous and less numerous tubules than the primary dentin, and sometimes they are completely absent  

(. Fig. 9.4c). It is characterized by being more mineralized and less sensitive than the primary dentin due to the lack of continuity of the tubules. If the odontoblasts are destroyed due to external aggressors, they are replaced by the mesenchymal undifferentiated cells that differentiate themselves in odontoblast-­like cells and secrete dentin matrix. They may not take the column-like and polygonal shape of the odontoblasts but a cubic or flat appearance. The resulting dentin has an interrupted continuity of the dentin tubules, acting as barrier against the penetration of external irritants [176]. The pulp inflammation must be understood as a defensive response that has by objective to limit the aggressive agent. The inflammation leads to vascular alterations, as the vascular dilatation and the increase of vascular permeability. The anatomic location of the pulp, among hard and nonelastic walls, associated to the lack of the collateral circulation is a factor that makes the pulp expansion difficult, which is observed after the increase of the blood flow (vascular dilatation) and vascular permeability, resulting in the increase of the pulpal pressure. On the vascular congestion, part of the interstitial liquid is pushed outward with the intention to accommodate the increase of blood flow. At the first moment, there is an increase of the arterial flow (arterial or active hyperemia), and at the next stage, there is a reduction of the venous flow (venous or passive hyperemia), producing the plasma exudation and the cell migration, characterizing the acute inflammation. However, the inflammation is a more complex phenomenon, controlled by the presence of chemical mediators that act on the defined stages and with specific functions. The pain is a consequence of the pressure increasing on the tissue due to the hyperemia, the edema, and the release of the inflammatory mediators (pain mediators).  

>> The pulp initially responds to the different stimuli with the dentin formation. If the intensity and the frequency of the stimuli are below the defense capacity of the pulp, there will be an inflammation with different intensities but with a reversibility potential of the inflammatory process. If the intensity and the frequency of the aggression are above the defense capacity of the pulp, there will be an irreversible inflammation. This irreversible inflammation can lead to the pulp necrosis.

The defense mechanisms of the dentin-pulp complex, even when they are effective on the maintenance of the pulp vitality, will have as a natural consequence the pulp aging process [37]. At this case, there is a reduction of cellularity and on the number of the vessels and nerves on the pulpal tissue. Consequently, there will be a reduction of the reparative capacity after the conservative treatments, such as the pulp capping and pulpotomy, which will be described later. On those situations, the treatment planning includes a thorough evaluation of the pulp condition, which will determine the clinical treatment to be performed.

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Assessment of Pulp Condition

The diagnosis of the pulp condition represents the base for proposing the treatment, especially when the patient’s chief complaint is related to pain. The pain is the most frequent reason patients seek dental treatment. It is an important reference for the dentist to reach a diagnosis, since there is no clear relation between the clinical symptoms and the histopathological findings. Therefore, the histopathological results cannot be extrapolated to the clinical conditions of treatment. For this reason, nowadays, the diagnosis is defined by the clinical conditions (pain) of the pathological pulp situation [36, 94, 97]. The challenge is to recognize the etiological factor responsible for the pain on the oral structures, which is fundamental for diagnosis and the success of the dental treatment [53]. For the diagnosis of the pulpal condition, it is not only necessary to understand the biological responses of the pulp, but also the interpretation of those responses. The diagnosis of the pulp condition can be divided in phases: anamnesis, intra- and extraoral clinical exam, pulp testings, complementary testings, and radiographic examination. 9.4.1  Anamnesis

The anamnesis represents the subjective examination performed through an interview to interrogate the patient, which directs the investigation in relation to the signals and symptoms associated with the pathological process. The clinical history must be collected and registered in an organized manner, using objective and defined questions. The anamnesis involves the analysis of the data obtained separately and interpreted in an associated manner to integrate the diagnosis process [53]. The anamneses are composed of the chief complaint, history of the current and previous disease, and the medical history of the patient. In some cases, the interaction with the doctor may be necessary to determine the general state and the medications used by the patient, assuring adequate planning and treatment. It is essential to ask the patient where and when the pain happens and if it is continuous, throbbing, spontaneous, or provoked. 9.4.2  Extraoral Clinical Exam

..      Fig. 9.6  Extraoral clinical exam showing a chronic draining fistula

9.4.3  Intraoral Clinical Exam

The intraoral clinical exam represents the objective exam of the signals that identify one specific disease [53]. The visual observation of the soft and hard tissues, associated with the physical inspection (by means of the clinical mirror, exploratory and periodontal probes), allows the identification of the carious lesions, crown and/or root fractures, presence of fistulas, restoration fractures, periodontal pockets, and pulp exposure. The intraoral clinical exam is not conclusive to reach a diagnosis about the pulp condition, and it must be associated with other clinical testings (. Fig. 9.7a–d).  

9.4.3.1  Palpation

The palpation allows determining, using the tactile perception, the consistence and texture of the soft  tissues, adherence, mobility, and smoothness, besides the presence of the painful areas. On the periapical abscess without fistula, the palpation allows verifying its stage of evolution  (initial, in evolution, acute) and if it presents a fluctuation sign (. Fig. 9.8) [53]. When it is pressed, the region corresponding to the lesion produces a painful sensation.  

9.4.3.2  Percussion

The percussion consists of a method in which the dentist applies soft tapping on the tooth crown with the aid of the handle of a clinical mirror, on the vertical and horizontal directions (. Fig.  9.9a, b) [94]. Even though it is a simple testing, the percussion is important to find the tooth responsible for a pain of endodontic origin, or due to a premature occlusal contact. The positive response to the vertical percussion  (the presence of pain sensation) may be associated with periapical alterations while to horizontal percussion can be associated with periodontal alterations [47]. One positive response to the percussion testing must always be confirmed by pulp sensitivity testing and radiographic exams.  

As a basic protocol for an extraoral exam, the dentist must observes the patient since  when entering into the  office. Signals of physical limitations, as well signals of facial asymmetry, may be present. A visual exam must be performed to determine if there is edema, extraoral fistulas, lacerations, excoriations, scarring, bruising, etc. The palpation of the face and the neck allows the dentist to determine if really there is an edema and if it is localized or diffused, firm, or fluctuating (. Fig. 9.6) [36].  

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a

b

c

d

..      Fig. 9.7  Intraoral clinical exam visually analyzing the soft and hard tissues. a Fistula (arrow); b darkened teeth associated with the pulp necrosis; c carious lesions; d fractured teeth showing a pink discoloration of the dentin due to the thin layer of remaining dentin over the pulp

ing must also be performed during the intraoral exam of the patient. It can be performed by the digital palpation or with the aid of dental instruments (. Fig. 9.10b).  

9.4.3.4  Transillumination

It consists in the application of an intense light on the lingual surface of a tooth. In the case of dental trauma, the transillumination is important on the diagnosis of fractures or cracks (. Fig. 9.11). On the tooth with necrotic pulp, generally the shadow of the pulpal chamber appears to be darker in relation to the rest of the crown, due to the decomposition of the pulpal tissue. On the teeth with vital pulp, this difference is not too evident.  

..      Fig. 9.8  Palpation of the periapical region

9.4.3.3  Periodontal Probing and Mobility

Testing

The periodontal probing allows to evaluate the presence or not of the periodontal pockets, gingival exudation, or even drainage via the gingival sulcus. The dentist must perform, whenever necessary, the indicated periodontal treatment for each clinical situation (. Fig. 9.10a). The tooth mobility test 

9.4.3.5  Pulp Sensitivity Testing

The pulp sensitivity can be evaluated using thermal (cold and heat) and/or electric testing. The pulp sensitivity testing aids on the differentiation of the teeth with normal pulps to the ones with pathologically altered pulps, especially on the cases of pulp necrosis, when the other teeth are used as control. Clinical studies were done to evaluate the performance of thermal and electrical testing on the determination of the pulp vitality [177]. It was observed that 97% of the teeth which responded positively to the

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a

b

..      Fig. 9.9  a Vertical percussion with the handle of a mirror; b horizontal percussion

a

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..      Fig. 9.10  a Periodontal probing; b tooth mobility testing

a low cost, and reproducible, those testings indirectly monitor the pulp vitality through the evaluation of the pulp nervous response, and not of the pulpal blood flow [83]. The thermal testing has a limited value to the diagnosis of the pulpal condition on the tooth with incomplete root formation and large apical foramen. On those cases, for the correct diagnosis, it must be considered the presence of irreversible pulpitis symptoms or periapical periodontitis; clinical signals of periapical infection (edema, sensitivity to percussion, mobility, and fistula); bone loss detected radiographically; progressive root resorption; and delay on the root development when compared with the adjacent teeth [29]. ..      Fig. 9.11  Transillumination showing the cracks on the tooth crown

testing presented pulp vitality, verified through the direct visual inspection of the pulp chamber. However, the results of the thermal testing must be interpreted with caution, because even though they are noninvasive, objective, with

Tip

Almost all teeth which responded positively to the pulp sensitivity testing presented pulp vitality. However, the thermal testing has a limited value on the tooth with incomplete root formation and large apical foramen, and other analyses are required.

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Understanding that the inflammatory pulp alterations are related to vascular changes, agents that cause modification on the blood flow (vasoconstriction or vasodilation) are capable to produce stimulation on the nervous termination, characterizing the possible clinical situation of the tissue (normal or inflamed, but still vital). However, several agents are capable to stimulate the sensitivity on the nervous termination, which will not necessarily certify that the tooth is vital. The nervous fibers are the last ones to suffer degeneration and, on the teeth with pulpal necrosis, can  sometimes still  respond with sensitivity when stimulated [53]. >> The nervous fibers are the last ones to suffer degeneration and, even on the teeth with pulpal necrosis, can sometimes still respond with sensitivity when stimulated.

Cold Test The thermal stimulations of the pulp with cold can be performed with an ice stick or cotton pellet soaked in a volatile refrigerant, such as ethyl chloride, tetrafluoroethane (Endo Ice®, Hygenic), dichlorodifluoromethane (DDM), carbon dioxide (dry ice or carbon dioxide snow), or a propane/ butane/isobutane gas mixture (Endo Frost, Roeko) (. Fig.  9.12a, b). Those agents promote a decrease of the intrapulpal temperature, stimulating pulp nervous terminations due to vascular changes (vasoconstriction), causing pain. The greater the temperature reduction, the greater the stimulus [53]. During the application of the cold test, cotton roll isolation must be used. The test must be initiated on the adjacent teeth or even on the analog tooth of that under suspicion of alteration, from posterior to anterior teeth, on the facial surface, and, finally, on the suspected tooth. The time of application of the cold test may vary from 1 to 4 s [53, 94]. The absence of painful response after the application of the thermal stimulus may indicate that the pulp is necrotic.  

a

Heat Test On the thermal testing performed with heat, a heated gutta-­ percha stick is applied over the labial surface of the anterior teeth or the occlusal surface of the posterior ones [94]. On this test, it is difficult to precisely control the temperature during the application. It is important that before the application, the tooth is lubricated with saliva or petroleum jelly, so that the gutta-percha does not stick to the surface. In the case of a positive response, the heat must be immediately removed. The excessive and prolonged heat must be avoided, which may cause irreversible pulp alterations (. Fig. 9.13a, b) [137]. The testing of the pulp sensitivity to with cold does not aggravate the situation of a normal or inflamed pulp. However, the opposite may be observed with the heat test, which should not be applied as a routine on pulps with normal characteristics [53]. The heat test is used in situations where it is required to establish a differential diagnosis, when the tooth with the symptoms is not easily identified. Due to the fact that heating can promote vasodilation, on the teeth with symptomatic pulp inflammation, depending on the extension of the process, the painful response to the heat can become intense and immediate.  

>> The testing of the pulp sensitivity with cold does not aggravate the situation of a normal or inflamed pulp. However, the opposite may be observed with the heat test, which should not be applied as a routine on pulps with normal characteristics.

Electric Pulp Test The electric test allows the evaluation of the pulp response to electrical stimulation over the nervous fibers on the pulp. The objective of this test is to stimulate the pulp sensitivity, but as the thermal tests, it does not give information over the blood supply, a determinant factor for the vitality [53]. The electric devices used for pulp sensitivity testing use different types of electrical current, and the high frequency is the most adequate, in which graduations may be regulated on a continuous mode. The positive response to the electrical

b

..      Fig. 9.12  Cold test. a Application of the Endo-Frost volatile refrigerant spray (Roeko) with a little cotton pellet; b touching of the small frozen pellet on the tooth to be evaluated

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b

..      Fig. 9.13  Heat test. a Heating of the gutta-percha stick over the flame; b touching the stick on the tooth to be evaluated

originated in the upper or lower arch. In addition, during the clinical examination, there is not a clear indication of the tooth with pulpal problem, and the results of thermal tests are not clear. On those cases, the area of the most suspected tooth can receive anesthesia, to evaluate if the painful sensation disappears. In case of a negative response, the next suspicion tooth or area also receives anesthesia, until the affected tooth is determined. 9.4.4  Radiographic Examination

..      Fig. 9.14  Device for electric pulp test. (Digitest Pulp Tester, Parkell Inc.)

test is noticed by the patients as a heating or tingling sensation, that disappears after the removal of the electrode (. Fig.  9.14) [94]. The absence of response to the electrical test on the cases of vital pulp may indicate a false-negative response, such as on the cases of traumas, calcifications on the root canal, incomplete root formation, patients that used analgesics or tranquilizers, or even defects on the device [33, 130, 132].  

Test Cavity Preparation The objective of this test is to evaluate the presence of painful response during the cutting of the dentin. It should be used if there is still doubt or inconclusive results about the pulp condition, after the use of the sensitivity testing to cold. On this testing, the dentin exposed by a caries lesion is removed with excavators or large diameter burs, without the use of anesthesia. The lack of painful response may indicate pulpal necrosis [94].

Local Anesthetic Test Sometimes, the symptoms are poorly referred or  localized, and the patient has a difficulty to describe whether the pain

The radiographic examination is a complementary resource used for the diagnosis of the pulpal condition, which allows the evaluation of the tooth mineralized structure and the apical and periapical regions. However, in some situations, the radiographic appearance of a pathological process may be very subjective. Therefore, the radiographic image is an important method but only complementary to the diagnosis. When not associated with anamnesis, clinical examination, and pulp sensitivity testing, the radiographic examination alone may lead to a wrong interpretation about normality or disease. >> When not associated with anamnesis, clinical examination, and pulp sensitivity testing, the radiographic examination alone may lead to a wrong interpretation about normality or disease.

Several factors may influence the quality of the radiographic interpretation, including the dentist’s ability when taking the radiography, quality of the film, X-ray radiation source, film processing, and the way that the radiography is visualized. Controlling all those variables may be a hard challenge, but it is essential to obtain a reasonable radiographic interpretation [87]. Besides the conventional radiography, direct digital images can be obtained with intraoral sensors. The digital radiography does not use films and does not need a chemical

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processing. A sensor is used to capture the image created through a radiation source. This sensor is attached directly or indirectly to a computer that interprets the signal and converts it into a digital image using specific software, allowing its exhibition and improvement. The image is stored and may be revised whenever necessary. The quality of diagnosis using digital radiography is comparable, but not superior to the conventional radiographic film, when properly exposed and processed [52, 87]. However, the exact pulp condition cannot be obtained by  radiographic examination  alone. On cases of reversible and irreversible pulpal alteration, the radiographic examination may show the presence of carious lesion or defective restorations, but the apical periodontal ligament may  be within normal limits or only slightly thickened, with an intact lamina dura [94]. However, when the pulp is necrotic, the examination may show the breaking of the lamina dura and the presence of the periapical lesions.

9.5

Diagnostic Hypothesis

The diagnosis must be understood as a dynamic process, performed with integrated stages (subjective and objective exams, clinical testing, and radiographic examination). Finishing the initial evaluation phase, the dentist must establish the diagnostic hypothesis, interpreting the collected data to plan and execute the treatment. The treatment to be performed (conservative or radical) will be based on the diagnosis of the pulpal condition, i.e., evaluating whether the pulp is vital or not. The odontogenic pain may basically have three origins: exposed dentin, pulpal inflammation, and periapical inflammation. Some clinical characteristics of pain collaborate during the establishments of the diagnostic hypothesis. Among them, it can be pointed the location of the pain, when it appears, its duration, frequency, and intensity. The dentin pain is generally acute and easily localized, provoked by specific stimulus, such as mechanic (touch), physical (cold or heat), chemical (acids), osmotic (sugar), and dehydration [111]. The pain occurs due to the movement of liquid inside the tubules, creating shear forces that stimulate the free nerve terminations, disappearing as soon as the causing agent is removed. The mechanoreceptors detect those movements leading to the generation of an action potential and consequentially the perception to the pain [102]. >> The odontogenic pain has basically three origins: exposed dentin, pulpal inflammation, and periapical inflammation.

Diagnosis to the pain of pulpal origin generally is more complex. The pain may be diffuse (referred or reflex), spontaneous, and throbbing, complicating the exact localization of the compromised tooth. The report of spontaneous pain discards almost always the possibility of the pulp to present

characteristics of reversible pathological alterations. In this case, the pathological acute pulpal alterations can be classified, only with the objective of clinical treatment indication, in acute reversible pulpitis (conservative treatment indicate) and acute irreversible pulpitis (radical treatment indicated) [94]. The protection of the dentin-pulp complex, defined as a conservative treatment, will only be indicated on the cases where the pulp presents characteristics of reversible pathological alterations. On those cases, the pain is acute and provoked, generally localized, with the duration of no longer than 1 minute, stopping after the removal of the stimulus. The indicated treatment is conservative, such as indirect or direct pulp capping, according to what will be explained later on [94]. In the cases of acute irreversible pulpits, the pain is sharp, spontaneous, and generally intense and throbbing, of long duration and sometimes diffuse and/or reflex. The indicated treatment is radical, through the biopulpectomy. On the teeth with incomplete root formation, even when the pulp has characteristic of irreversible alteration, the pulpotomy will be indicated, which is the removal of the pulpal tissue only on the crown area, allowing the finishing of root formation [94]. The acute irreversible pulpitis may develop slowly to a chronic pulpitis. That pulp alteration is generally observed on young patients, resulting from a low-level and long-term irritation, over a pulp with great resistance. Clinically, two types of chronicle pulpitis can be observed: ulcerative and hyperplastic chronicle pulpitis. The ulcerative chronic pulpitis is characterized by presenting an ulcer on the exposed surface of the pulp, isolating the remaining pulp tissue by means of a barrier of an ulcerated tissue and defense cells. Generally, the pain is provoked, localized, and produced by the compression of food in the carious cavity. The regular  indicated treatment is biopulpectomy. On the teeth with incomplete root formation, the pulpotomy will be indicated [94]. The hyperplastic chronic pulpitis is characterized by the proliferation of a granulomatous tissue on the level of pulp exposure, named pulp polyp. The pain is generally provoked, localized, and produced by the compression of food during mastication. The indicated treatment is the biopulpectomy. On the teeth with incomplete root formation  the pulpotomy is indicated [94]. The acute and chronicle pulpitis, depending on the pulp condition and on the intensity of the aggressor agent, may develop slowly or fast to the death of the pulp. The pulp necrosis is generally asymptomatic and can produce a color change of the tooth crown. Generally, there are no response to the pulp sensitivity testing, but on doubtful cases, the cavity preparation test must be performed. The indicated treatment is the necropulpectomy. >> The protection of the dentin-pulp complex, defined as a conservative treatment, will only be indicated on the cases where the pulp presents characteristics of reversible pathological alterations.

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Tip

The diagnosis of pulp condition can be summarized as shown below: 55 Reversible pathological alterations: The pain is acute and provoked, generally localized, with the duration no longer than 1 minute, stopping after the removal of the stimulus. 55 Acute irreversible pulpits: The pain is sharp, spontaneous, and generally intense and throbbing, of long duration and sometimes diffuse and/or reflex. 55 Ulcerative chronicle pulpitis: Characterized by presenting an ulcer on the exposed surface of the pulp; the pain is provoked, localized, and produced by the compression of food in the carious cavity. 55 Hyperplastic chronic pulpitis: Characterized by the proliferation of a granulomatous tissue on the level of pulp exposure. The pain is generally provoked, localized, and produced by the compression of food during mastication. 55 Pulp necrosis: Generally asymptomatic, it can produce a color change of the tooth crown. Generally, there are no response to the pulp sensitivity testing, but on doubtful cases, the cavity preparation test must be performed.

Several factors such as caries, tooth preparation, occlusal trauma, operative procedures, and marginal microleakage, besides resinous components that may reach the pulp, have the capability to promote pulpal alteration and will be discussed later [74]. The correct diagnosis of the pulpal ­condition and the knowledge about the factors that may promote pulpal alterations, separately or in association, are essential to allow the dentist performing dental procedures maintaining the vitality of the pulpal tissue, reducing the damage, and promoting the rehabilitation. 9.6.1  Carious Lesion

The caries disease promotes alterations on the pulp through the diffusion of bacteria and its by-products through the dentin tubules. The degrees of pulpal lesion are determined by the characteristics of the patient (age, caries risk, and potential of tissue response) and by the characteristics of the lesion (cavity depth, size of the lesion, and mineralization degree of the dentin) [128]. Therefore, the maximum preservation of remaining  dentin separating the pulpal tissue of the cavity floor  is very important. On asymptomatic and well-sealed teeth, the maintenance of the pulp vitality after tooth preparation on dentin without pulp exposure is excellent, even when some residual carious dentin tissue remains [74]. 9.6.2  Tooth Preparation

9.6

Origins of Pulpal Alterations

In the past, it was believed that the main causes of pulpal inflammation were the toxic effects of the restorative material. However, from the half of the 1970s decade, several researches have shown that the pulp can tolerate a variety of restorative materials if bacteria are absent, depending obviously on the type of material and whether it is or it is not in direct contact with the pulpal tissue [74]. Therefore, the main cause of the pulp alterations is the bacterial invasion and their toxins on the pulpal tissues, especially by the lack of sealing on the margins and of the dentin tubules that were cut during the preparation [75]. However, the direct contact of the materials with cytotoxicity and immunosuppressive effect with the pulpal tissue contributed for the persistence of tissue inflammation [83]. Cytotoxic materials may destroy specific pulpal cell, reducing its capability to respond to a future bacterial invasion [74]. >> The main cause of the pulp alterations is the bacterial invasion and their toxins on the pulpal tissues, especially by the lack of sealing on the margins and of the dentin tubules that were cut during the preparation. However, the direct contact of some materials with the pulpal tissue may contribute to the persistence of tissue inflammation.

In order to perform the tooth preparation, a rotating cutting instrument assembled on high- or low-speed handpiece, a high-power laser, or an air abrasion device can be used [30]. Those instruments are capable to generate heat in a larger or smaller degree, and it may cause alterations on the pulpal tissue due to the temperature rise, producing postoperative sensitivity or even necrosis [141]. According to Zach and Cohen, the temperature rise of the pulpal tissue must not be superior to 5.5 °C above the body temperature, due to higher risk of irreversible tissue alterations and pulpal necrosis [180]. Studies verified that the action of the rotary cutting instruments produces movement of dentinal fluid, toward the pulpal tissue and toward the tooth surface, due to the heating generated by the use of a non-correctly refrigerated instrument. This movement is also observed when the preparation is excessively dried with air stream [21, 122]. The excessive force applied by the dentist over the handpiece during the tooth preparation can also cause more heat [159]. The increase of the force applied may be the result of a small hand sensitivity, stress, and wrong dentist’s technique or reduced cutting effectiveness of the rotary instruments [141]. In order to minimize the trauma, new rotary cutting instruments with high cutting effectiveness must be used, associated with the abundant refrigeration and application of small and intermittent cutting force. In addition, excessive drying of the preparation with a strong air stream must be avoided, being preferably performed with small cotton pel-

303 Protection of the Dentin-Pulp Complex

lets, absorbent papers, or small indirect and intermittent air stream [128]. The use of unbalanced and eccentric cutting instruments or handpieces causes a greater frictional heat by the vibration and must be replaced or repaired [66, 128]. Tip

In order to reduce aggression during the tooth preparation, the dentist needs to: 55 Reduce and apply intermittent force over the handpiece 55 Use new rotary cutting instruments and copious refrigeration 55 Avoid excessive drying of the preparation 55 Not use unbalanced and eccentric cutting instruments or handpieces

9.6.3  Occlusal Trauma

Restoration with excessive occlusal contact transfers the chewing load to the tooth, pressing the periodontal ligament on an abnormal manner, causing a periapical inflammation and pain [128]. The pain is localized and throbbing. The patient describes pain when the teeth are in contact, which is related to a very slight dental extrusion, making the patient avoid teeth contact [95]. In order to prevent or solve this problem, the dentist must always adjust the interarch contact after finishing the restorations, evaluating it on centric occlusion and during the protrusive and lateral excursive movements. 9.6.4  Restorative Procedure

The marginal microleakage is the passage of ions, fluids, and bacteria through the tooth-restoration interface due to the lack of sealing or a noneffective contact between the restorative material and the tooth preparation. The microleakage is associated with the bacterial infection of the dentin and secondary caries, favoring the infection and necrosis of the pulpal tissue, and failure of the restorative material, with the total or partial displacement of the restoration [66, 138].

The marginal microleakage is the passage of ions, fluids, and bacteria through the tooth-restoration interface due to the lack of sealing or a noneffective contact between the restorative material and the tooth preparation.

The correct use of the adhesive systems allows an adequate bonding of the restorative material to the tooth structure, reducing the microleakage and extending the longevity of the restorations [138]. However, in order to perform the adhe-

sive technique, operative procedures such as the acid etching, hybridization, and light-curing of the restorative material, besides the restorative material by itself, can cause pulp alterations [128]. 9.6.4.1  Acid Etching

The acid etching of dental enamel increases the surface roughness and energy, by selective dissolution of the hydroxyapatite crystals, which is penetrated by the adhesive monomers, creating resinous microtags and micromechanical bonding. On the dentin, due to its composition and characteristics, the etching tends to cause a movement of the ­dentinal fluid, due to its hypertonic action [124]. It promotes a thorough cleaning of the surface, removing the smear layer and the smear plugs, demineralizing the peritubular and intertubular dentin and exposing the collagen fiber network, increasing the dentin permeability due to the opening of the tubules, and creating a direct path to the pulpal tissue. If the dentin is not properly sealed by means of the adhesive system application, the tubules will remain open, allowing bacteria and their irritating by-products, as well as irritant components of restorative materials, reach the pulp [109]. When the self-etching adhesive systems are used, the demineralization and the penetration of the adhesive monomers occur simultaneously. Therefore, instead of the tubules being opened and then sealed later, as on total-etch materials, they remain closed, reducing the chances of pulpal contamination. 9.6.4.2  Dentin Hybridization

The hybridization of the dentin consists in the impregnation of the collagen fiber network exposed by the acid etching with the resinous monomers of the adhesive system. This procedure may produce an adequate sealing of the tooth-­ restoration interface, but not in a permanent way [113]. The degradation of the interface allows pulp irritation due to marginal microleakage into interfacial gaps and/or the nanoleakage on the base of the hybrid layer, on interfibrillar spaces not properly infiltrated by the adhesive [49, 86]. In case of a heterogeneous impregnation of the hybrid layer, the dentin tubules may remain open, allowing the movement of the dentinal fluid, activating the pulp nociceptors, and resulting in a postoperative sensitivity [38, 128]. Besides the failures that may occur on the of hybridization process, some components of the adhesive systems have cytotoxic and immunosuppressive effects and can diffuse through the tubules and reach the pulpal tissue, especially on the very deep cavities, with less than 0.5 mm of dentin remaining [38, 177]. A study evaluated the effect of acid etching and application of an adhesive system on very deep cavities, without the pulpal protection [69]. The authors verified a persistent inflammatory response on the pulp when the globules of the resinous materials reached the pulp through the tubules, starting a foreign body inflammatory pulpal response, characterized by the presence of the macrophages and giant cells with multiple nuclei. Another study evaluated the response of the dentin-pulp complex on very deep Class V cavities restored with total-etch adhesive sys-

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tem and c­omposite resin [72]. The authors verified the occurrence of hyaline changes of the cellular matrix, related to the local edema and the overflow of the blood plasma from the capillaries, which were dilated and congested on the coronary pulp. The displacement of odontoblasts was observed when the thickness of the dentin remaining, between the pulp tissue and the pulpal wall, was smaller than 0.3 mm. The knowledge about the characteristics of the tooth substrate may minimize the adhesion failures, and reduce the diffusion of the adhesive system components to the pulpal tissue, through the dentin tubules. Therefore, in deep and very deep cavities, it is necessary to use a protective material before the acid etching and hybridization, avoiding that the adhesive system becomes a source of irritation of the pulpal tissue. >> In deep and very deep cavities, it is necessary to use a protective material before the acid etching and hybridization, avoiding that adhesive system becomes a source of irritation of the pulpal tissue.

9.7

 actors Affecting the Dentin-Pulp F Complex Protection

To protect the dentin-pulp complex means to protect the dentin and the pulp against the action of external aggressive agents, aiming to preserve its vitality. In order to do so, besides the correct diagnosis of the pulpal condition, some other factors must be considered, such as the depth of the preparation, the age of the patient, the presence of sclerotic dentin, the material used for the protection, and the type of restorative material. The depth of the preparation is determined by the thickness of the dentin remaining between the cavity floor and the roof of the pulpal chamber [26]. The clinical determination of the cavity depth is a difficult procedure, and it must be assisted by the radiographic examination of the tooth structures. The thicker is the dentin remaining between the cavity floor and the roof of the pulpal chamber, the better the prognostic for the pulp will be, because the thickness of the remaining is the most important factor to protect the pulp from external aggressions. As it has already been stated in Chap. 5, the preparation can be classified, accordingly to their depth, in shallow, medium, deep, and very deep. However, it is very difficult to clinically determine the depth of the cavity, because it is not only related to how many millimeters of depth the cavity has, since the volume of the pulpal chamber decreases with aging. Therefore, a cavity of only 2 mm deep on a first permanent molar of an 8-year-old child may be considered very deep, but it may be considered shallow on this same tooth when the patient reaches 40 years old. The teeth of younger patients, with some exceptions, present a large pulpal chamber and  dentin tubules, which will favor the penetration of toxic or irritating agents. The only clinical

aspect that can give to the dentist an absolute information about the cavity depth is when a pink discoloration is observed on the pulpal wall, indicating that probably less than 0.5 mm of dentin remaining is covering the pulp. In this case, some small pulpal exposures can be present, not visible to naked eyes, and the cavity is named very deep, as it is observed in . Fig. 9.7d.  

>> The depth of the preparation is determined by the thickness of the dentin remaining between the cavity floor and the roof of the pulpal chamber. The thicker is the remaining, the better the prognostic for the treatment. The conservation of the dentin remaining is more important for the health of the pulpal tissue than the application of a protective artificial material. When a pink discoloration is observed on the dentin, that indicates that less than 0.5 mm of dentin remaining is covering the pulp and some small pulpal exposures can be present, not visible to the naked eyes.

During the tooth preparation, the dentist must preserve the largest amount possible of dentin, since the remaining dentin will protect the pulpal tissue, acting as a thermal isolation and physical and chemical barrier against the penetration of the bacteria, toxins, and acids. In vitro studies showed that a dentin remaining of 0.5 mm thick is able to reduce the toxicity level of restorative materials up to 75%, while 1 mm thick reduces up to 90% [106]. With a remaining of 2 mm thick, on most of the cases, the pulpal response is inexistent [75, 156]. The dentin has an excellent buffering capacity to neutralize the acids that come from the cariogenic activity, as well as the one used for the acid etching for the adhesive technique. The conservation of the dentin remaining is more important for the health of the pulpal tissue than the application of any protective artificial material [75]. In an attempt to perform a more objective estimate about the amount of dentin remaining, the electrical conductance of the dentin can be evaluated. The method is based on fact that the smaller is the remaining, the greater is the passage of an electrical current. The Prepometer® device (Hager) presents an electrode to be placed on the oral mucosa of the patient, while the reading tip closes the circuit when touching the dentin (. Fig. 9.15). The visual indication about the dentin remaining quantity is given by the LEDs that light up. Depending on the cavity depth, the color of the LED that lights up is changed. The green LEDs represent a safe distance, the orange ones represent a limit zone of safety, and the red ones represent danger of pulpal exposure. In the absence of this device, the dentist must develop a concept about the cavity depth, through the observation of the cavities with exposed pulps or during the opening of the crown for the endodontic treatment, associated to the analysis of the radiographic images. Another possibility is the study using extracted teeth, making cross sections on the mesiodistal and facial-lingual directions. Another factor that influences the necessity of a protective a material application is the presence of sclerotic dentin on the cavity floor, which can be clinically seen as an area  

305 Protection of the Dentin-Pulp Complex

with darkened brownish or black color, extremely hard to the touch (. Fig. 9.16a). It indicates that a long-lasting and low-­ intensity aggression took place, allowing a deposition of minerals inside the tubule, leading to its sealing. Radiographically, it can be seen as a radiopaque area (. Fig. 9.16b). The sclerotic dentin is capable to effectively seal the dentin and protect the pulp, making unnecessary the application of any additional protective material.  

 

>> The sclerotic dentin can be clinically seen as an area with darkened brownish or black color, extremely hard to the touch. It is capable to effectively seal the dentin and protect the pulp, making unnecessary the application of any additional protective material.

9.8

Cleaning of the Tooth Preparations

After the tooth preparation with hand or rotary cutting instruments, an amorphous and thin layer is deposited upon the tooth surface, named smear layer, composed of organic and inorganic materials from the tooth structure, oil from

the rotary instruments, saliva, blood, and microorganism from the carious process. This layer represents a natural protection of the dentin-pulp complex against the invasion of bacteria and its toxic and acid by-products, because it occludes the tubules and reduces the dentin permeability. On the other hand, the presence of the smear layer also presents disadvantages, as the direct interference on the bonding mechanism of some adhesive systems and maintenance of the bacteria in the preparation walls [111]. Due to those observations, the cleaning of the preparations is a recommended procedure, which allows the protection of the dentin-pulp complex by the reduction of microorganisms through the friction, washing, or chemical action. This procedure reduces the contamination, eliminating residues of the preparation and loose enamel and dentin fragments, oil from the handpieces, blood, and saliva, besides contributing with the action of the protective agents. The cleaning of the preparation is a continuous process which starts with the use of cutting instruments and washing the cavity with air/water spray, and continues with the rubber dam placement and use of cleaning agents or antiseptics, immediately before the application of a protective material and restoration of the tooth [111]. The cleaning agents can be classified in demineralizing, when react with the smear layer removing it partially or completely; and non-demineralizing, when they act by the simple washing action, removing the loose residues or promoting the disinfection. 9.8.1  Demineralizing Cleaning Agents 9.8.1.1  Phosphoric Acid

..      Fig. 9.15  Device to determine the cavity depth using the measurement of electrical conductance (Prepometer—Hager)

a

The acid gels, mainly the phosphoric acid, promote an effective cleaning of the tooth surface [23, 62, 91, 101]. Several acids may be used to produce the necessary microporosities for the retention of the adhesive system on the enamel, but the 30–50% phosphoric acid, more commonly 35–37%, is the choice as a conditioning agent [2]. After the tooth preparab

..      Fig. 9.16  a Sclerotic dentin on the floor of the cavity exhibiting the brownish or darkened coloration; b radiopaque aspect of the sclerotic dentin in the radiography (arrow)

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tion, washing, and drying, the phosphoric acid is applied over the preparation for 15 s. Its thoroughly  washing with water must be performed, at least, during  the same time it was used for conditioning [111]. After the washing, the tubules will be opened and the dentin collagen fibers network exposed. When the surface is dried with a stream of air the water inside the interfibrillar spaces, which maintains the collagen web expanded, is evaporated, producing its collapse and  closing the nanometric interfibrillar spaces essential for adhesive monomer penetration. Therefore, the dentin overdrying must be avoided. The fourth- and fifth-generation adhesive systems produce better results when applied over a wet dentin, that is, when just the excess of water is to be removed with the blot drying technique, using small cotton pellets, leaving the surface slightly wet [145]. This procedure prevents the collapse of the collagen fibers, allowing a deeper penetration of the adhesive system and consequentially higher bond strength. In addition, the blot drying also avoid the aspiration of the odontoblasts cells into the dentinal tubules, generally observed when the dentin is overdried with air stream. 9.8.1.2  Polyacrylic Acid

When the indicated protective agent is the glass ionomer cement (GIC), the preparation cleaning can be performed with 10–25% polyacrylic acid gel. It can be applied over the preparation walls with disposable applicators during 10–30s, followed by washing and drying with gently air stream. This procedure increases the bond strength of the GIC to the tooth structure, without the cause damage to the pulp on shallow, medium, and deep cavities [39, 133]. As it is less aggressive, it just removes the smear layer but does not expose the dentin collagen or opening of the tubules. Therefore, the cavity can be dried with soft air stream without the risk of collagen collapse. However, some studies disagree about the effectiveness of the previous application of the polyacrylic acid on the tooth surface, even though other studies stated that it really works [117]. 9.8.2  Non-demineralizing Cleaning Agents 9.8.2.1  Detergent

The anionic detergents are cleaning agents that act reducing the surface tension of the liquids. They do not have a bactericide action, but they interact with the residues of the tooth preparation, keeping them suspended in the solution and allowing its removal [111]. The detergent molecules have an alkyl tail and a head formed by oxygen, sodium, and potassium atoms. The tail is hydrophobic and lipophilic, and the head is hydrophilic, characterizing an amphoteric substance. When the tail acts as an anion, the solution is called anionic. When the tail is a cation, the detergent is cationic [114]. The anionic detergents are biocompatible, the opposite of the cationic ones, which have an antimicrobial activity, but harm live tissues.

The most used detergent is the sodium lauryl sulfate (SLS) solution on pH 6.4. It is efficient in the removal of blood and oil from the preparation, and it has a moistener and emulsifier action but does not remove the smear layer [62]. It must be applied on the preparation using disposable applicators, followed by washing and drying with soft air stream. It may be used to clean the preparation walls before the amalgam restoration procedure. 9.8.2.2  Aqueous Solution of Calcium

Hydroxide

The aqueous solution of calcium hydroxide may be used in preparation of any depth, and is the most indicated to clean deep and very deep cavities, during the stepwise excavation and during the operative procedures for the direct protection of the dentin-pulp complex. The aqueous solution of calcium hydroxide, with pH 12, inhibits the enzymatic activity of the microorganism, acting as a bacteriostatic and hemostatic agent, besides stimulating the formation of sclerotic and reparative dentin [111]. The solution can be prepared by the dentist, by adding 10 g of pure calcium hydroxide of pro-analysis (p.a.) quality into 100 ml of distilled water. After the mixture, a suspension is produced that may be immediately used. After some time, the calcium hydroxide that did not dissolve will deposit at the bottom of the bottle. There is no need to shake the bottle before use, because the alkaline solution created is already saturated. The solution can be stored for up to 3 months [115]. After the end of the tooth preparation and isolation of the operating field, the preparation can be washed with a calcium hydroxide solution, using small hydrophilic cotton pellets or disposable applicators soaked with the solutions, brushing it for 15 s (active application) or using a Luer syringe with a needle (passive application). Then, the cavity can be dried with small hydrophilic cotton pellet or with soft air stream [111]. In case of pulpal exposure, the solution is applied on the cavity with the small sterile cotton pellet until the hemostasis is obtained. 9.8.2.3  Chlorhexidine Gluconate

The chlorhexidine gluconate is an antimicrobial substance commonly used as a mouthwash for the reduction of bacterial biofilm formation in the oral environments. Due to its positive charge is adsorbed during the topic application on the tooth surface, biofilm, and oral mucosa, which present a negative charge. Its releasing is gradual, allowing a continuous antimicrobial effect (substantivity). It is also adsorbed by the cellular walls  of the bacterias causing the lysis of the microorganisms [178]. When used in low concentrations, its action may be bacteriostatic by the inhibition of the ATP synthesis by the bacteria. In high concentration, it presents the bactericidal effect by the rupture of the cytoplasmic membrane. As cleaning agents of the tooth preparations, the 2% chlorhexidine can be used for disinfection of the walls before

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or after the acid etching, and it does not interfere in the adhesion process [60, 103, 126]. The chlorhexidine has been used to inhibit the action of the protease enzymes improving the durability of the hybrid layer [24, 125]. The dentin matrix metalloproteinases (MMPs) are a class of calcium- and ­zinc-­dependent endopeptidases, incorporated into the mineralized dentin matrix during odontogenesis. Those may be released after acid etching, producing the degradation of the unprotected collagen fibers inside the hybrid layer [58]. The application of chlorhexidine on the collagen network exposed by the acid etching, before the application of the adhesive, reduces the degradation of the hybrid layer, increasing the durability of the adhesion. 9.8.2.4  Fluoride Solution

The use of fluoride solutions has the aim to reduce the formation of secondary caries under amalgam restoration [2111]. A 2% sodium fluoride aqueous solution on a neutral pH can be applied for 2–4 min [8]. The high concentrations of fluoride in contact with preparation walls have a bactericidal or bacteriostatic effect, due to the capacity of the fluoride ion to penetrate through the plasma membrane and destroy the bacteria [174]. Additionally, it promotes the deposition of calcium fluoride over the preparation walls, acting as a fluoride reservoir that will be released if there is a reduction of the pH. Its application is indicated only before amalgam restorations because it can impair the acid etching for adhesive procedures. 9.9

Protective Materials

The materials available to protect the dentin-pulp complex have a large range of composition, depending on its physical, chemical, mechanical, and biological behavior. In order for a protective material to be considered ideal, it must be capable to [111]: 55 Protect the dentin-pulp complex from thermal and electrogalvanic shocks 55 Be bactericidal or inhibit the bacterial activity 55 Bond to the tooth structure and release fluoride 55 Remineralize the demineralized dentin remaining after tooth preparation of teeth with carious lesions of fast progression 55 Hypermineralize the underlying dentin 55 Stimulate the formation of tertiary reactional or reparative dentin on the deep lesions or pulpal exposures 55 Be biocompatible maintaining the pulp vitality 55 Prevent the discoloration of the tooth, inhibiting the penetration of metallic ions from the amalgam restorations into the surrounding dentin 55 Avoid the penetration of toxic or irritating substances from the restorative materials into the dentin tubules and pulp 55 Improve the marginal sealing of the restorations, avoiding the microleakage of the saliva and microorganisms into the tooth/restoration interface

A protective material should also present a modulus of elasticity similar to the dentin, adequate mechanical strength, low solubility and copolymerize with the resinous restorative material [40]. Unfortunately, no protective material presents all those characteristics. The materials to protect the dentin-­ pulp complex are indicated for the application over the remaining dentin tissue or directly over the exposed pulp tissue. The dentist must evaluate the characteristics and the properties of each material as well as carefully evaluate the clinical case to be treated. The materials to protect the dentin-pulp complex may be classified in the following categories: 1. Sealers: They are materials that produce a thin protective pellicle that covers the tooth structure recently cut during the tooth preparation. They are applied over all walls with the aim to seal the dentin tubules. Examples are the varnishes, dentin desensitizer, and adhesive systems. 2. Liner: They are materials applied in layers with a thickness between 0.2 and 1 mm, over the pulpal or axial walls. They are used to act as a physical barrier to the microorganisms and its by-products, to seal the dentin tubules bonding to the tooth structure, besides acting as a thermal and electrical isolator. They may also present a therapeutic action through the antibacterial effect, fluoride release, pain relief, recovery of the pulpal tissue health, or stimulation the of the calcified tissue formation. Some examples are the calcium hydroxide and glass ionomer cements. They are generally applied only on the deeper areas of the preparations. 3. Bases: They are materials used to protect and/or replace the dentin, allowing that a smaller volume of the restorative material is applied. It can also be used to fill retentive areas in preparations for the indirect restorations or to give an adequate geometry for amalgam preparations. They are used in a thickness larger than 1 mm, according to the need to reconstruct undermined walls. Some examples are the zinc phosphate, zinc oxide-eugenol, zinc polycarboxylate, and glass ionomer cements, besides the flowable composites. The use of bases must be performed with a caution for amalgam restorations, since the larger the base thickness, the smaller the fracture resistance of the amalgam restoration will be [55, 80]. There are several materials available to protect the dentin-­ pulp complex, which the most used ones will be described next. The adequate choice of the protective material must be based on the evaluation of the pulpal tissue condition and on the factors that lead the indication of the protective materials, as it has already been described. >> The materials to protect the dentin-pulp complex are applied over the remaining dentin tissue or directly over the exposed pulp tissue. They are classified as sealers (thin pellicle), liners (0.2 and 1 mm), or bases (more than 1 mm).

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9.9.1  Cavity Varnish

It is composed of a natural (copal or colophony) or synthetic (nitrocellulose) resin dissolved on an organic solvent, which can be the acetone, chloroform, ether, etc. [111, 128]. It presents a moderate thermal and electrical isolating property. The cavity varnish can be considered a sealer and used to protect the dentin-pulp complex under the amalgam restorations. The use of cavity varnish reduces the passage of the electrical current and minimizes the diffusion of metallic ions from the amalgam restorations into the tooth structure, avoiding the darkening of the tooth when low-copper amalgam alloys are used. They allow an initial reduction of the microleakage in association with amalgam restorations, and would be indicated as a protective agent in shallow cavities or in association with other protector materials in deeper cavities [26]. Due to the fact that the film thickness is very thin, it does not act as a thermal isolator [75]. The use of the cavity varnish has been drastically reduced, since the high-copper amalgam alloys used today do not present a significant γ2 phase (Sn7-8Hg) and, consequentially, suffer less corrosion (deposition of metallic ions of tin oxide and/or tin oxychloride) on the tooth-restoration interface [2]. Although they were largely used in the past, several studies showed that the varnish is not capable to promote a good sealing of dentin, even if applied on several layers. In addition, it suffers dissolution with the time, leaving an empty space on the interface that must be occupied by the corrosion products of the amalgam. It is also less effective than the use of the dental adhesives to reduce the marginal microleakage [1]. For those reasons, they are almost not used anymore. 9.9.2  Desensitizing Agents

Some studies indicate the use of a desensitizing agent after the application of a liner or base, before amalgam restorations, despite the preparation depth, replacing the cavity varnish [14, 139]. The goal of the desensitizer is to reduce the dentin permeability and consequently the movement of fluids through the dentin tubules. Among the available materials, there are the aqueous solutions of 35% hydroxyethyl methacrylate (HEMA) associated or not with 5% glutaraldehyde [138]. The glutaraldehyde-based solutions promote the precipitation of the dentinal fluid proteins, through its denaturation, forming plugs inside the tubules [143]. Some studies analyzed the use of GLUMA Desensitizer (Heraeus Kulzer) after the full crown preparation [57]. They concluded that tooth sensitivity was significantly reduced in comparison to preparation where the desensitizer was not applied. In relation to the biocompatibility of desensitizer agent components, some studies observed that glutaraldehyde and the HEMA present cytotoxic, mutagenic, and cytopathic effects [41, 70]. Another study suggested that the use of desensitizer containing glutaraldehyde and/or HEMA must be performed with care, because they present a high diffu-

sion capability through the dentin, mainly on the cases of young patients, as well as on very deep tooth preparations, where the dentin is very permeable [40]. 9.9.3  Adhesive Systems

The mechanism of action of an adhesive system, as a protective agent to the dentin-pulp complex, is based on obtaining a sealing zone on the tooth surface, by deposition of a homogeneous layer of resinous material which occludes the dentin tubules [40]. When applied on shallow and medium depth cavities, they are biocompatibility and favorable for the maintenance of the pulp vitality. However, on deep and very deep preparations, its components can diffuse through the dentin tubules and reach the pulpal tissue. Nonpolymerized residual monomers and resin globules that are present inside the tubules may reach the pulpal chamber by the dentin fluid. Some studies showed that the direct contact of the resinous components with cell or pulpal tissue present toxicity [41, 70, 81, 151, 161]. Therefore, the adhesive systems must be used with care. For the indirect protection, on the cases of deep or very deep preparation, more biocompatible liners or bases must be applied before the adhesive system application. The use of the adhesive systems as materials for direct protection of the dentin-pulp complex was described some years ago [84]. Even though some studies have showed promising results on animals, the persistent inflammatory response of the pulpal tissue was verified on the cases of direct pulp capping of human teeth, resulting in the phenomenon of anachoresis, where the microorganisms invade the inflamed pulpal tissue with low defense capability. Therefore, the cytotoxic and immunosuppressive effects of the adhesive system components and the possibility of increasing of adhesive failures, in case of pulpal tissue exposure, contraindicate the use of those materials for the direct protection of the dentin-pulp complex [173]. 9.9.4  Zinc Oxide-Eugenol Cement

The zinc oxide-eugenol cements (ZOE) are generally available as a zinc oxide powder and a eugenol-containing liquid. The setting is based on an acid-base reaction that consists in the hydrolysis of the zinc oxide and a later reaction between the zinc hydroxide and eugenol to form a chelate. There are four different types of ZOE cements: Type I, used for temporary cementation; Type II, indicated for long-lasting cementation of fixed prosthesis; Type III, indicated as a temporary restorative material or base for the thermal isolation; and Type IV, for long-lasting temporary restorations up to a year [2]. They were largely used in the past and, still today, are very useful on dental procedures on the public health system as temporary restoration. Although they present a deficient marginal sealing, they are effective on the sealing against the biological leakage due to its antibacterial properties [74, 119].

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They must not be used in direct contact with the pulpal tissue, because of its irritating and cytotoxic effect [44]. The liner and bases prepared with this material allow a good thermal isolation [131]. However, they have ­non-­satisfactory mechanical properties and can increase the microleakage under amalgam restorations [55, 99]. In addition, the presence of the free residual eugenol on the cement can interfere in the adequate polymerization of composites, and they should never be associated [2, 31, 179]. Based on the fact that materials with better properties are available, such as the GICs, the ZOE cements must be used only as a temporary filling material or for temporary cementation [111]. 9.9.5  Glass Ionomer Cement

The glass ionomer cement is composed of a powder and a liquid that when mixed together start a setting reaction to form a solid material [117]. On the conventional GIC, the setting reaction is of the acid-base type, where the polyacrylic acid attacks the surface of the glass particles (fluoride-­ containing calcium aluminosilicate), and the calcium, aluminum, sodium, and fluoride ions are released into the aqueous mean. The polyacrylic acid chains cross-links with the calcium ions, forming a solid mass (calcium cross-links). In the next phase, the calcium is replaced by the aluminum ions in 24 h. The sodium and fluoride ions do not participate on the cross-links of the cement, but they combine to be released as sodium fluoride. The cross-linked phase becomes hydrated throughout time, with the same water used for the mixture, adding strength to the cement (maturation process). The portion of the glass particles that did not react is covered by a silica gel (silica gel sheath), formed by the leaching of cations from the outer portion of the particles. This process may last for up to 7 days [2117]. Right after the mixture of the material, the pH is acid, but it tends to neutralize in 24 h [34]. On the resin modified glass ionomer cement (RMGIC), additionally to the acid-base reaction, a mechanism of chemical and/or light-activated polymerization was incorporated to the material, so that some of the disadvantages of chemical curing materials were minimized [2, 117, 160]. Therefore, hydrophilic monomers and the methacrylate modified polyacrylic acid are used and allow fast curing of the material when light-activated. On some systems, during the monomer polymerization process, a chemical reaction also occurs, promoted by an activator/initiator system, that has an advantage to assure the complete curing of a resinous component even in the absence of light. The GICs present several positive properties for a protective material, such as the chemical bonding to the tooth structure, fluoride release, and the antimicrobial effect [111, 116, 117]. The conventional GIC presents coefficient of linear thermal expansion similar to the tooth structure, while on the RMGIC, this coefficient varies according to the percentage of the resinous component incorporated to the material [116]. In relation to the cytotoxicity, the conventional one has been proven to be less toxic than the one modified by resin

[3, 153]. The incorporation of HEMA on the composition increases the cytotoxicity of the material, probably due to the residual uncured diffuses through the dentin tubules, which is related its low molecular weight [3]. Some studies verified that the RMGIC is toxic to the culture of human pulp cells, and it is not recommended on the cases of direct pulp protection [90]. However, other  studies verified that the RMGIC did not cause an inflammatory reaction on the pulpal tissue when applied as a liner on deep Class V preparation, and they can be used as a material for the indirect protection of the dentin-pulp complex [74, 152, 154]. Although less toxic, the conventional GIC should not be used as a material for direct protection as well, because it presents certain toxicity when in direct contact with the pulpal tissue, even though it is very biocompatible when used for indirect protection, even in deep preparations. >> The GICs present several positive properties for a protective material, such as the chemical bonding to the tooth structure, fluoride release, and the antimicrobial effect.

Before using the conventional GIC, a 10–25% polyacrylic acid conditioner should be applied on the tooth surface, for 15–30 s, followed by washing for 20–30 s and drying with a gentle air stream. When the conventional cement is applied as a liner or base, the restorative material is applied over, protecting it from the syneresis and water absorption phenomenon. However, when the conventional  GIC is applied completely filling the preparation, getting contact with the saliva, there is a need for surface protection of the material with a layer of some impermeable substance, such as the cavity varnish, clear nail varnish, or dental adhesives. When the RMGIC is used, there is no need for a surface protection, because the resinous matrix reduces drastically the syneresis and water absorption by the material, resulting in the so-­ called umbrella effect. When the conventional GIC is used as a line or base before the adhesive restorative procedures, the acid etching of the cement must not exceed 20 s, in order to prevent damages to the material. The acid etching of the GIC surface increases its bonding to the composite applied later on, by the increase of the superficial roughness of the cement layer [76].

Tip

55 For improving the bonding of GIC to the tooth structure, a previous polyacrylic acid etching can be performed. 55 When a preparation is completely filled with a conventional GIC, the surface must be protected with a thin varnish or adhesive layer until the ending of the setting reaction. This procedure is not necessary for RMGIC. 55 The GICs should not be directly applied over the exposed pulp tissue.

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9.9.6  Calcium Hydroxide

55 Cauterization of the pulpal tissue due to the alkaline properties of the calcium hydroxide (pH >12). Some studies demonstrate that the calcium hydroxide is The use of calcium hydroxide was introduced in Dentistry, in capable to solubilize and release bioactive dentin 1920, by Hermann [95]. Until today, the calcium hydroxide-­ molecules that stimulate the formation of the calcified containing products are still used for protection of the tissue, such as the bone morphogenetic proteins and the dentin-­pulp complex due to its capability to stimulate the transforming growth factor, which are important formation of tertiary dentin, protect the pulp against thermediators of pulp repair [74]. moelectrical stimuli, antibacterial and acid neutralizer 5 5 On the first few days, it was histologically verified the action, antiexudative effect, besides promoting formation formation of a superficial layer of necrotic tissue, mineralized tissue. The calcium hydroxide-containing prodinfiltrated of inflammatory cells and bleeding. The ucts are available, according to the clinical application, as a alkaline pH neutralizes the lactic acid secreted by the powder, paste, suspensions, solutions or cement. osteoclasts and may help to prevent the destruction of The application of the calcium hydroxide powder over the the mineral tissue, acting as a buffer against the effects of pulpal exposure must be limited to the exposed pulpal tissue the inflammatory process [110]. In addition, the calcium area only, and never extends up to the dentin walls and marions may reduce the capillary permeability, allowing a gins of the tooth preparation. The calcium hydroxide paste greater availability of the calcium ions on the mineralizamay be prepared by the dentist with distilled water and caltion regions [73]. cium hydroxide powder or obtained readymade by a manu5 5 Throughout the days, the inflammatory response is facturer (Calcicur—Voco, UltraCal—Ultradent). As all gradually reduced, and a matrix rich in collagen is calcium hydroxide powder or paste does not set, it is necesformed in contact with the necrotic zone or directly sary to cover it with a layer of calcium hydroxide cement and, adjacent to the liner material, by the differentiation of over it, a layer of GIC [111]. stem cells in odontoblast-like cells and production of The calcium hydroxide is also available as chemically amorphous and non-tubular dentin matrix. activated or light-cured cement and indicated as a cavity 5 5 The mineralization occurs after the secretion of the liner. The calcium hydroxide cement promotes protection amorphous tissue that is irregular and contains numeragainst the thermoelectrical stimuli. The chemically actious cellular inclusions. After that, a dentin-like tissue vated cement is presented in two pastes that must be mixed with tubules is formed, covered by odontoblast cells, before the use. Its mechanical properties, especially comcalled “dentin bridge.” It can be observed about 30–45 pressive strength 7 min after the mixture and shear strength days after the direct capping. after 10 min, allow it to be indicated as a liner in cases of indirect protection on very deep cavities, under the amalgam restorations, because it would resist to the condensation The calcium hydroxide also presents the antimicrobial effect, because few oral microorganisms survive on an alkaline stress [35, 100]. The solubility of the calcium hydroxide cements in acidic environment produced by this material, hindering the residconditions, under restorations with the deficient marginal ual microorganisms that remain contaminating the site of sealing, produces its softening and complete dissolution, exposure to interfere on the repair [13]. The low cost and the resulting in empty spaces in the tooth-restoration interface, predictable repair of the pulpal exposure, when the treatment that may increase microleakage and reduce the fracture is performed based on the correct diagnosis and technique, resistance of the large restoration [22, 88, 129, 175]. To over- make the calcium hydroxide the best material for direct pulp come this problem, light-activated materials were devel- protection procedures [74]. oped, being more acid resistant and having a higher >> The calcium hydroxide is considered the best material compressive strength. These materials do not need to be for direct application over the exposed pulp, with a mixed prior to use. The resinous monomers present on its large clinical and scientific evidence of its efficacy. composition allow some bonding to the resinous restorative materials. According to several studies, the calcium hydroxide is considered the most indicated material for direct application 9.9.7  Mineral Trioxide Aggregate (MTA) over the exposed pulp, due to the consistent clinical and scientific evidence [13, 74, 110]. In a revision of 14 clinical stud- The MTA was described initially by Lee et al., in 1993 [92]. ies, including more than 2300 cases of direct pulp capping Since then, it has been researched and indicated in several with calcium hydroxide, a success rate above 90% was clinical situations, such as the direct pulp capping, pulpotobserved [12]. The exact mechanism explaining how the cal- omy, retrograde obturation, sealing of root perforations, apicium hydroxide promotes the deposition of hard tissue over cal barriers for apexification or apexogenesis, and most the pulp exposure is not completely understood; however, recently a sealer for root canal obturation [18, 74, 110, 120, the sequence of repair after the treatment of a healthy exposed 140, 164]. The MTA is a mixture of the refined Portland cement, pulp with the calcium hydroxide may be summarized as folbismuth oxide (that gives radiopacity), SiO2, CaO, MgO, lows [13]:

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K2SO4, and Na2SO4. It must be mixed with sterile water, on the ratio of 3:1 (three parts of powder to one of water) [120]. The Portland cement is a mixture of a dicalcium silicate, tricalcium aluminate, gypsum or calcium sulfate (added to control the setting time of the cement), and the tetracalcium aluminoferrite [28, 142]. Portland cement is the worldwide name for the material commonly known as a cement, used in civil construction. It is defined as hydraulic binder, that is, a product that hardens only through the reaction with water but also forms a waterproof product. However, the MTA and the Portland cement used on the construction work are not identical materials, because the first one has smaller and standardized particles and few toxic heavy metals (such as copper, manganese, strontium, and arsenic), following a strict manufacturing process for production of medical materials, which allows the standardization and purity of the composition, as well as the prevention of the contamination [82, 121, 140]. After the hydration of the MTA, the material forms a colloidal gel that gets solid after 2–3 h [46]. The initial pH of the cement that has just been prepared is 10.2 rising to 12.5 3 hours after the mixture. When the MTA powder is mixed with water, there is a formation of calcium hydroxide, which is responsible for the high alkalinity after the hydration, allowing the material to be considered bioactive and present a capacity to allow an adequate environment for the repair of the pulpal and periradicular tissue. The calcium hydroxide formed releases calcium ions for adhesion and cell proliferation; creates an alkaline mean with antibacterial and antifungal properties; modulates the production of cytokines; promotes the differentiation and migration of the hard tissue-forming cells; and forms carbonated apatite when exposed to the physiological solutions, promoting the biological repair [20, 59, 64, 140, 165]. However, different from the powder of calcium hydroxide, the MTA promotes a sealing of the tooth structure, when used to seal the root or furcation perforations or for retrograde obturation. It is available in white or gray colors [74]. Due to the fact that the gray MTA may cause tooth staining by the presence of iron and manganese ions on its composition, the white MTA was developed to be used on regions that might have an esthetic involvement, even though some studies also have verified discoloration of roots obturated with white MTA [74, 120]. The lower concentration of the iron (FeO), aluminum, and magnesium ions on the white MTA is responsible for its color [20, 46, 59]. The particles of the white MTA are smaller than the ones of the gray MTA, and its setting time is faster [121]. The setting time of the MTA is of 2 h and 45 min, which requires, after the protection of the pulp tissue, the application of a fast setting cavity liner or base over it, such as a GIC or a RMGIC, making possible to restore the tooth at the same treatment session [163]. Another option is to perform the procedure to protect the pulp on two separate clinical sessions. In the first one, the direct protection with the MTA is performed, and a small sterile cotton pellet embedded on distilled water or physiological solution is applied over the MTA, to allow the setting of the cement, followed by a tem-

porary restoration. On the second session, the temporary restoration is removed, and then a final restoration is made. One disadvantage of the MTA is that its cost is higher than the pure calcium hydroxide. The cost to buy 1 g of white MTA corresponds approximately to the amount of money enough to buy 276 g of calcium hydroxide cement or 816 g of the calcium hydroxide p.a. Clinically, the MTA has been used in the cases of direct pulp protection. Many studies analyzed the effect of MTA on pulp capping on intact teeth, using various animal models (dogs, pigs, and cats) and demonstrate the capacity of the MTA (gray or white) to promote the biological repair of the exposed area with the formation of a thick barrier of the mineralized tissue, keeping the pulpal tissue without inflammation and maintaining the vitality [5, 11, 19, 25, 71, 104, 134, 144, 169]. Clinical studies have shown that the MTA has a similar capacity of calcium hydroxide to promote the pulp repair in the case of exposure. Up to this moment, there were not enough number of scientific evidences to claim that the MTA is better than the traditional calcium hydroxide, which effectiveness and high percentage of success are largely reported in the literature [74]. It seems that the greater advantage of the MTA lies on the fact that it can set and a seal by itself the exposed area. However, due to the long setting time, it must be kept in mind the use of a GIC over the MTA so that the immediate restoration can be performed, as it happens with the calcium hydroxide p.a., which limits its advantages on the cases of pulp exposure on a cavity that will be immediately restored [74]. On the other hand, the use of the MTA in other circumstances, such as perforations on the root and the retrograde obturation, turns it into a material with incomparable value, once the chemical setting will make it remain in a position and seal the cavity after closing and suture the flap. >> There is not enough of scientific evidences that MTA is better than the traditional calcium hydroxide for direct pulp capping.

9.9.8  Materials Containing Bioactive

Molecules

Several dental materials have been studied and developed based on the strategy of repair and regeneration of dentin, through the stimulation of the pulpal cells by bioactive subtances that would be incorporated to the restorative materials. The scientific knowledge in relation to the development of the new materials has been obtained through researches on molecular biology, related to the odontogenesis and tissue repair mechanisms [40]. Several proteins are produced by the pulp and are incorporated in the dentin matrix during the odontogenesis, such as the bone morphogenetic proteins (BMP) and the transforming growth factor beta (TGF-β), known to be capable to stimulate the hard tissue-forming cells [50, 149]. The proteins capable to modulate the cell  functions have been called cytokines, growth factors, or cell modulators [79].

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In the cases of caries lesions, the bacterial acids promote the demineralization of the dentin and the release of the modulator proteins, which bind to specific membrane receptors of the odontoblasts and/or their cytoplasmic process. That can stimulate the secretion of several types of specific dentin proteins, resulting in mineral deposition inside the dentin tubules near the carious lesion (dentin sclerosis), as well the deposition of the reactionary dentin in the pulpal chamber [98, 146, 148, 172]. When the aggression is of high intensity, such as in the cases of dentin overheat, overdrying, or application of acid etching on very deep cavities, the death of odontoblasts may occur with the aspiration of those cells into the dentin tubules. This way, the undifferentiated mesenchymal cells or pre-odontoblasts, according to the conditions and the characteristics of the pulp before the aggression, are stimulated to differentiate into odontoblast-like cells and secrete the amorphous and non-tubular dentin matrix, characteristic of the tertiary reparative dentin. Several molecular and biochemical events are involved in the process of the biological repair of the pulpal tissue. However, the cell membrane receptors may be activated by metabolically active proteins [38, 40, 98, 146, 148, 172]. Some studies have shown positive results with the use of those molecules on the direct pulp capping [67, 170]. However, difficulties on the developing of the materials containing those bioactive molecules have also been verified, especially on the development of a scaffold to lead the molecules to the site of pulp exposure [171]. However, they may represent the future of the protection agents for the dentin-­pulp complex [38, 166]. Dental materials that contain bioactive glasses have been added to composites and RMGIC to improve its biological effects, presenting the capability to release calcium and phosphate and to form the hydroxyapatite over the dentin. The β-tricalcium phosphate, a bioceramic material that presents the biological property to work as a scaffold for the bone development, being progressively reabsorbed as the growth of the mineralized tissue takes place, was used in a study as material for direct pulp protection [144]. The authors verified that it promoted the repair of the pulpal exposure, with the formation of the hard tissue and the preservation of the pulp tissue vitality. 9.10 Techniques for Protection

of the Dentin-Pulp Complex

The techniques to protect the dentin-pulp complex may be classified in two groups. The first one includes the techniques of indirect protection, where the protective material is applied over the dentin, while the second one includes the techniques of direct protection, where the protective material is applied over the exposed pulpal tissue.

9.10.1  Indirect Pulp Protection

The indirect protection of the dentin-pulp complex consists in the application of the protective materials over the remaining dentin, when pulpal tissue exposure has not occurred. It can be performed after finishing the preparation and immediately before applying the restorative material, in deep and very deep cavities, named just indirect pulp capping. It can also be done after the partial removal of the carious tissue, when it is intended to reopen the cavity later to finish the removal of the remaining carious tissue, in case of the stepwise excavation procedure. In this last case, it is desired that the protective material stimulates the remineralization of the caries-affected dentin tissue, avoiding a pulpal exposure that could occur if a total removal of the softened dentin had been performed immediately.

The indirect protection of the dentin-pulp complex consists in the application of the protective materials over the remaining dentin, when pulpal tissue exposure has not occurred. The techniques are the indirect pulp capping (after total infected dentin removal) and the stepwise excavation (after partial infected dentin removal).

9.10.1.1  Indirect Pulp Capping

The aims of the indirect pulp capping are to block the thermal, electrical, and chemical stimuli that come from the restorations and from the oral environment, to produce a therapeutic effect over the dentin-pulp complex, maintain the pulp vitality, avoid or reduce the microleakage and the bacterial growth under the restorations, and improve the marginal sealing properties [26]. The indirect pulp capping is performed immediately after the end of the tooth preparation, as an additional protection to the pulp in deep and very deep preparation, where there is no sclerotic dentin. Generally, the dentists used to recommend that all carious tissue should have been removed before the restoration. However, exactly defining where is the carious dentin tissue is a very hard task. Due to the demineralization process, the dentin tissue becomes softened, and the analysis of this parameter was initially recommended in order to take a decision about what should be removed. It was recommended that the entire softened dentin should be removed until a hard tissue was reached, which could be identified due to a unique sound that the hard dentin produces when it was touched with the exploratory probe. This procedure inevitably results in a great number of pulpal exposures on deep and very deep cavities, especially on acute lesions. Later studies have shown that the lesion presents three distinct layers. The superficial layer corre-

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sponds to a liquefaction necrosis, highly contaminated. Below it there is an intermediary layer of demineralized and highly contaminated tissue, known as the infected dentin, and then a deeper portion that is demineralized but little infected, known as the affected dentin. It was then recommended that just the necrotic and infected dentin should be removed, keeping the affected dentin which could remineralize. However, although several attempts were performed to differentiate both layers, with the use of dyes  or other methods, this distinction was many times very difficult, if not impossible. On the other hand, some studies have shown that even when infected dentin remained in the preparation walls, the restored teeth presented a similar success rate to the ones that had the entire softened dentin removed [61, 105, 135, 136, 162]. It was shown that the softened carious dentin can remineralize and becomes hard again, and the viable bacteria can be reduced or eliminated when the preparation is properly restored. It was proved that the removal of the entire carious tissue is not necessary for the success of the restorative treatment. However, it is essential to obtain a restoration with an adequate marginal sealing in order to eliminate the nutrition source for the remaining bacteria [136, 162]. >> The removal of the entire carious tissue is not necessary for the success of the restorative treatment. However, it is essential to obtain a restoration with an adequate marginal sealing in order to eliminate the nutrition source for the remaining bacteria.

Apart from the kind of treatment to be selected, with the total or partial removal of the carious tissue, when the preparation is deep or very deep, the use of a protective material that stimulates the remineralization and isolates the pulp from the irritating effect of the direct restorative material, such as the adhesive systems and composite resins, or from the thermal stimuli on the amalgam restoration, becomes essential. In order to make the indirect capping, after the end of the tooth preparation, the cleaning of the cavity can be performed with a of 2% chlorhexidine solution, anionic detergents, or calcium hydroxide solution, before the application of the protective agents of the dentin-pulp complex. The materials indicated for indirect pulp capping are selected according to the depth of the preparation and the restorative material to be applied. On shallow and of medium depth preparations, due to the amount of remaining dentin protecting the pulp tissue, no additional protective material is necessary, regardless of the type of the restorative material to be used. For amalgam restorations, a solution of anionic detergent can be applied into the cavity, followed by washing and drying. The restorative material may be directly applied. Another option is to apply, after the detergent washing and drying, a 2% sodium fluoride solution for 2–4 min on the preparation walls, fol-

lowed only by drying with an air stream, which will result in the deposition of calcium fluoride on the walls, aiming to reduce the chances of a future caries lesion in the tooth-­ restoration interface. Another possibility is to wash the cavity with an air and water spray, followed by drying it with air stream. Then, calcium hydroxide solution or 2% chlorhexidine solution or a glutaraldehyde-based desensitizer is applied, followed by another drying with the air stream. When the amalgam is chosen as a restorative material, the smear layer must not be removed, remaining on the walls to seal the tubules and reduce the dentin permeability. Therefore, the demineralizing agents should never be used. For composite restorations on shallow and medium depth cavities, the 35–37% phosphoric acid gel is applied if a total-­etch adhesive system will be used. After washing the acid, the surface must remain wet, removing only the excess of moisture by the blot drying technique, followed by adhesive system application. Another option is to gently dry the surface with a soft air stream and then to apply a of 2% chlorhexidine solution to hydrate it again and to impregnate the collagen fibril network, in order to reduce the long-term degradation of the collagen fibers by the dentin metalloproteinases. Then, the drying is performed through the blot drying technique, using a small cotton pellet, followed by the adhesive system application, drying, and light-curing. In those cases, the adhesive layer applied will promote the sealing of the dentin tubules and control of the sensitivity, besides bonding to the composite restorative material. In case of the self-etching adhesives, the acid primer will promote the etching of the dentin and the formation of the hybrid layer without the need of a previous phosphoric acid application. When performing amalgam restorations on deep preparation, when the proximity with the pulpal tissue is greater, but it is not possible to observe any area in the pulpal or axial walls with a pink discoloration, a protective material must be applied in the internal walls in order to promote thermal isolation to the metallic restoration; otherwise, tooth sensitivity will probably come up when hot or cold food contacts the tooth. The material of choice is usually the chemical or light-­ cured GIC. The previous treatment of dentin with polyacrylic acid for 15–30 s can be performed, followed by the washing and drying with a gentle air stream. For composite restorations, the GIC should also be used (. Fig. 9.17a–d). The preferable instrument used for application is the calcium hydroxide liner placement instrument, which has a small sphere at the end that allows to precisely apply the material on the internal preparation wall (. Figs. 4.46b and . 9.17c). The calcium hydroxide cement does not need to be used on deep cavities. On very deep cavities, where areas of the internal walls with pink discoloration can be observed, some clinically undetected pulp microexposures  may exist. Therefore, it is  

 

 

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..      Fig. 9.17  Indirect pulp capping on deep preparation using glass ionomer cement. a Large carious lesion on tooth upper premolar; b removal of the carious tissue, showing the deep internal walls; c mixed

glass ionomer cement being caught by a calcium hydroxide liner placement instrument; d liner material applied on the pulpal and axial walls

necessary to use a material that is capable to stimulate the odontoblasts to form mineralized tissue to protect the pulp. The most adequate material for this situation is the calcium hydroxide cement, which can be dispensed over a mixing pad, mixed with a No. 22 spatula and taken into position with a calcium hydroxide liner placement instrument. Its application must be performed only over areas with pink discoloration, in layers of 0.5–0.7 mm, and not over other regions [139]. Over the calcium hydroxide cement and in the rest of the pulpal or axial wall with deep dentin, a layer of GIC should be used [75]. After the initial setting of the cement, the amalgam or composite restoration can be performed (. Fig. 9.18a–g) [139].

oral environment only by a thin layer of the carious dentin, which if removed may cause the exposure of the pulp. It is also recommended when there is doubt about the capacity of the pulp to keep the vitality after a strong aggression caused by the carious process. For that, the removal of the carious dentin is performed in two clinical sessions, being possible to re-evaluate the condition of the pulp and allow a remineralization of the dentin tissue. On the first clinical session, the entire carious dentin is removed from the external walls of the preparation, and only the demineralized dentin tissue over the pulpal and axial walls should remain, as it is shown in . Fig.  9.19a–f. After that, the cleaning of the preparation is performed using a calcium hydroxide solution or an anionic detergent or a 2% chlorhexidine solution, followed by drying of the walls with soft air stream. Over the softened tissue on the internal walls, a layer of calcium hydroxide cement liner is applied. The whole preparation is then filled with a temporary restoration made of GIC or RMGIC. The surface of the material must be protected with a varnish, if a chemical curing GIC is used, avoiding the syneresis or water absorption. In cases of large preparations, the use of a syringe is recommended for easier  material applications. Its technique of use is shown in . Fig. 14.43a–f.

 

>> The indirect pulp capping is performed only in deep and very deep preparation, when there is no sclerotic dentin.

9.10.1.2  Stepwise Excavation

The stepwise excavation is indicated in the cases of very deep acute carious lesion, in young patients, with the absence of spontaneous pain and with response to the tactile and thermal stimuli, specially to the cold with a fast relief [77, 150]. It is applied in a situation where the pulp is separated from the

 

 

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After finishing the temporary restoration, the occlusal contacts must be adjusted and periapical radiography obtained to use as control. This restoration can remain in place for a period of 30–45 days up to 1 year, so that the carious lesion activity is reduced and allows that dentin-pulp complex to remineralize the demineralized dentin and forms sclerotic and/or tertiary, significantly reducing the number of

microorganisms and the risk of pulpal exposure during the removal of the remaining carious tissue, on the next opening of the cavity [17, 74, 93, 118]. On the second session, after the waiting period, the anamnesis, sensitivity, and pulp vitality tests must be repeated. The radiographic exam may show the formation of sclerosis or tertiary dentin below the remaining dentin. With a positive

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..      Fig. 9.18  Indirect capping in very deep preparation. a Initial aspect; b opening the cavity to obtain full access to the lesion; c removal of the carious tissue; d very deep region over the mesio-­ lingual pulp horn with pink discoloration; e equal portions of the base and catalyst pastes of calcium hydroxide cement being placed over the paper mixing pad; f material being mixed with a No. 22 cement spatula; g mixed material being caught with the end of a calcium

hydroxide liner placement instrument; h application of the calcium hydroxide cement over deepest area with pink discoloration; i application of a layer of GIC over the entire pulpal wall; j application of the primer; k application of the adhesive; l application of composite increments in the undermined enamel areas; m placement of oblique increments; n finished restoration

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..      Fig. 9.18 (continued)

317 Protection of the Dentin-Pulp Complex

determination of the pulp vitality and absence of any symptoms, the treatment can be continued, removing the remaining carious dentin. For that, the anesthesia and the isolation of the operating field are performed. The cavity is open, and the remaining carious dentin can be removed using large diameter round bur (No. 4, 6, or 8) in low-speed handpiece. Extreme care must be taken at this moment to avoid pulpal

exposure. Then, the preparation cleaning is performed using calcium hydroxide solution, anionic detergent, or 2% chlorhexidine solution. Considering that the stepwise excavation is performed on very deep cavities, the protective material indicated is the calcium hydroxide cement, applied only on areas next to the pulp with pink color, if they exist. If there were no areas with pink discoloration, just a layer of GIC is

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..      Fig. 9.19  Stepwise excavation. a Deep carious lesion in which the entire removal of the carious tissue could result in pulp exposure; b, c total removal of the carious tissue from the surrounding walls, without touching the pulpal wall; d necessary materials (1, calcium hydroxide cement; 2, glass ionomer cement powder and liquid; 3, protective varnish); e application of a calcium hydroxide cement layer over the demineralized dentin; f temporary restoration with glass ionomer

cement; g after the waiting period, removal of the temporary restoration and remaining carious tissue is performed avoiding to expose the pulp; h lining with glass ionomer cement; i application of the universal matrix and wooden wedge; j after the application of the adhesive system, the restoration of the proximal contact was done; k restoration of the dentin with opaque composite; l finished restoration after the application of the enamel shade composite (Grandio SO—Voco)

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g

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..      Fig. 9.19 (continued)

applied, and the final restoration is performed. After that, the occlusal contact adjustment is required (. Fig. 9.19g, h). The aim of the stepwise excavation is to block the aggressions that reach the pulp from the carious lesions through dentin tubules, hindering the metabolic circuit that occurs due to the oral fluids and the bacteria of the carious tissue, inactivate the bacteria by bacteriostatic or bactericide effects of the calcium hydroxide, remineralize the remaining demineralized dentin, hypermineralize the underlying health dentin, and stimulate the formation of reactional dentin. Those effects allow the complete removal of the remaining carious tissue on the second clinical session, without the exposure of  

the pulpal tissue [111]. Several studies have shown that when the cavity is opened again, the color of the lesion changes from light brown to dark brown, the consistency changes from wet and soft to dry and hard, and the number of viable Streptococcus mutans and Lactobacillus are significantly reduced or even completely disappear. The radiographic image may show no change or even decrease of the radiolucent area, the dentin sclerosis, or the formation of tertiary dentin [74]. Clinical studies reported high success rate with the stepwise excavation and showed that, in 83% of the treated teeth, the pulp presented normal clinical response to the vitality

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tests [127]. They observed that the immediate success (60– 90 days after the treatment) depends on the initial clinical condition of the pulp, and the long-term success is directly related to the quality of the final restoration. They also verified that the age of the patient did not influence the success rate. In addition, just the partial removal of the carious tissue reduces the risk of pulpal exposure in up to 98%, when compared to the removal of the entire carious tissue on deep preparation [74]. In order to perform the treatment, the pulp vitality must be confirmed with pulp sensitivity testing, and the reversibility of the inflammatory response must be evaluated. The report of spontaneous pain that is not relieved with the use of analgesics turns the prognosis of the treatment somewhat doubtful. Radiographically, the tooth must not present periapical alterations and internal or external resorption. The use of the calcium hydroxide on the stepwise excavation has its effectiveness proved by several authors, promoting the remineralization of the demineralized dentin and the reduction of the inflammatory response of the pulp, due to its bactericidal and bacteriostatic properties [51, 54, 155]. However, the type of the material used is less important for the success of the treatment than to obtain a restoration with an adequate marginal sealing, during the waiting period between the first and second clinical sessions [56, 74, 127]. 9.10.2  Direct Pulp Protection

The direct protection of the dentin-pulp complex consists of the placement of a protective material directly over the exposed pulp, to maintain its vitality and promote the pulp healing and the formation of a mineralized barrier over it. The technique for direct protection of the dentin-pulp complex may be divided in three types: direct pulp capping, pulp curettage, and pulpotomy.

The direct protection of the dentin-pulp complex consists of the placement of a protective material directly over the exposed pulp, to maintain its vitality and promote the pulp healing and the formation of a mineralized barrier over it. The techniques are direct pulp capping, pulp curettage (superficial pulp removal), and pulpotomy (pulpal chamber pulp removal).

9.10.2.1  Direct Pulp Capping

The direct pulp capping is indicated in the cases of mechanical or accidental exposure, when the pulp is vital and sound, or with a reversible inflammation [26]. This situation generally occurs during the tooth preparation, where the accidental exposure of the pulp may happen, and in the cases of dental traumas. The most important factors directly related to the success of the direct pulp capping are the correct diagnosis of the pulpal condition, the absence of bacterial

c­ ontamination, the use of adequate protective materials, and the effective sealing of the cavity with a proper restoration [74]. Some studies showed that it is more probable that the treatment of the exposed pulp is successful, when the exposure has happened due to mechanical reasons than when it happens due to caries [74]. The penetration of the caries lesion toward the pulp will result in the bacterial invasion and the pulp inflammation. This causes the pulp to be less capable to respond and to heal itself, compared to what is seen when there is a mechanical exposure and the inflammation is not present [74]. >> The key factors for the success of the direct pulp capping are the correct diagnosis of the pulpal condition, the absence of bacterial contamination, the use of adequate protective materials, and the effective sealing of the cavity with a proper restoration.

The presence of bacteria on the pulp exposure areas must be avoided, once several studies have shown the adverse effects of the bacterial contamination [22, 42, 43]. Therefore, the direct pulp capping is more indicated when the exposure is recent, and any contamination is not associated with a real pulp infection. In addition, the rubber dam isolation and the operating field disinfection are important to reduce the contamination possibility. In the cases of pulp contamination due to trauma, it is important to evaluate the patient’s clinical history, the time that pulp is exposed to the oral environment, the extension of the tooth fracture, the quality of the tooth remaining, and the viability of the restorative treatment. The most favorable responses are obtained when the treatment of the pulpal tissue occurs up to 24 h after the trauma [26]. The calcium hydroxide powder or paste is still the most used material for the direct protection of the dentin-pulp complex [74]. However, the MTA has also been indicated and used for this purpose. A clinical study evaluated the direct pulp capping made with the calcium hydroxide in 249 teeth, during 16 years [45]. The authors verified that the treatment was most favorable in patients with age under 40 years old in relation to the patients with age over 60 years old. They also verified that the probability of loss of the pulp vitality after the treatment was significantly greater in the first 5 years of treatment. In the favorable cases, the dentin bridge closing the exposure must be formed 30–45 days after the procedure [4]. >> The greater chances of success of direct pulp capping are on patients under 40 years old in relation to those with age over 60 years old. After a trauma, the most favorable responses are obtained when the treatment occurs within the first 24 h.

If the exposure happens during the cut of healthy dentin, on the final phase of the tooth preparation, the protection of the exposed area must be performed before the preparation is concluded. If the preparation is being performed without the rubber dam isolation and an exposure occurs, the immediate isolation and the antisepsis of the operating field with 2%

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chlorhexidine solution should be performed before the capping. However, the chlorhexidine must not be applied over the exposed pulp. If the exposure occurs during the removal of a deep caries lesion, and the removal of the remaining carious tissue will result in an increase of the exposure, it must be interrupted and the capping be made. If the remaining carious tissue does not coincide with the exposure area, the capping should be performed and the remaining carious tissue removed, since this procedure does not lead to new exposures. To avoid the contamination of the exposed pulp area, the complete removal of the surrounding carious tissues is always recommended before using cutting instruments on the internal walls, because if an exposure occurs, the contamination will be reduced. In . Figs. 9.20a–i and . 9.21a–d, it is shown the sequence for the direct pulp capping. The preparation is irrigated with a saline solution or calcium hydroxide solution, because they are less aggressive to the pulpal tissue [74]. Bleeding must be controlled to allow adequate contact between the protective material and the exposed pulpal tissue. Among the factors that have shown a significant role in the success of the treatment is the bleeding control. The presence of the interposed blood clot, between the calcium hydroxide or MTA and the pulp, may make the lesion repair reactions difficult. In addition, the bleeding that does not stop may indicate a greater degree of pulp inflammation, resulting in a reduction of the reparative capacity. The moisture and the contamination of the dentin area adjacent to exposure, due to the bleeding, may turn it difficult to reach an adequate sealing of the restoration and to prevent the later marginal microleakage [74].  

 

>> During direct pulp capping, the bleeding must be fully controlled to allow adequate contact between the protective material and the exposed pulpal tissue. The presence of the interposed blood clot between the calcium hydroxide and the pulp will make the repair difficult.

After the hemostasis, the cavity is dried with sterile small cotton pellets or a sterile piece of absorbent paper. After that, a solution composed by an association of antibiotics and antiinflammatory, sold with the name of Otosporin® (GlaxoSmithKline—otologic suspension—association of hydrocortisone, polymyxin B sulfate, and neomycin sulfate) or Maxitrol (Alcon—ophthalmic solution—association of dexamethasone, polymyxin B sulfate, neomycin sulfate), is applied using small pellets soaked with the medication during 10 min, directly over the pulpal tissue (. Fig. 9.20e). A new irrigation with saline or calcium hydroxide solution is performed to remove the medication. Then, the area is dried with a sterile cotton pellet. Then a material to stimulate the formation of dentin bridge is applied over the exposed area. This material can be the MTA or calcium hydroxide p.a. (powder or paste). The protective material must be applied over the pulpal tissue, without compression, and only on the surface of the exposed pulp, and the excess is removed (. Figs. 9.20g and 9.21b). In  

 

order to facilitate the placement of the material in the correct place, an intraoral carrier can be used (. Fig. 4.50b), which is filled with the material. It presents a plunger that, when pushed, projects the material outward the tip, allowing its application (. Fig.  9.20f). Over this material a layer of calcium hydroxide cement should be applied, covering a little further than the exposed area, in such a way that the applied powder is protected (. Figs. 9.20h and 9.21c). As the calcium hydroxide cement must be protected from the acid etching, and the rest of the cavity is deep and also needs to be protected, a layer of GIC is applied over the whole internal wall, in case the final restoration is immediately  performed (. Fig. 9.20i) [75]. After the GIC setting, the cavity may be restored with amalgam or composite, and then the occlusal contact evaluated. Another option is to completely fill the cavity with GIC, to certify that there are no symptoms of pain on the days following the procedure (. Fig. 9.21d). It is necessary to wait a period of 45–60 days for the postoperative control. After this time the pulp sensitivity testing to cold is performed, and also a new radiographic exam is done, in order to evaluate the periapical area looking for signals of pulpal necrosis. The tooth must remain without symptoms [63]. In the case of pulp vitality, absence of symptoms and periapical lesions, the removal of the superficial portion of the GIC can be done, and the final restoration is performed.  

 

 

 

 

9.10.2.2  Pulp Curettage

This procedure is recommended, for example, when the pulp has been exposed due to a dental trauma and the pulp horn is projected outward the dentin wall, or when the patient has delayed some time to look for the dental treatment, resulting in the contamination of the superficial pulpal tissue. It is mostly indicated on teeth with incomplete apex formation. The procedure consists in the superficial removal of a small amount of the pulpal tissue, exposing the underlying tissue without inflammation or bacteria, increasing the exposed area available for contact with the protective material [111]. According to some authors, on the cases where the pulp is too contaminated, this technique presents the inconvenience of not knowing exactly if all the necrotic focus in the pulpal tissue were removed, especially the ones that are on other areas of the coronary pulp far from the pulp exposure site. In this case, the pulpotomy should be the better indication [78]. Other authors claimed that the curettage must be performed only on the cases of incomplete root formation, due to the fact that in this case, the pulp presents a greater blood supply [138]. In the cases where the root apex is complete, the pulpotomy should be performed to increase the success rates of the procedure [9, 10, 26]. The sequence for pulp curettage is presented in . Fig.  9.22a–l. To perform this procedure, the anamnesis, radiographic exam, and clinical diagnosis of the pulp condition have to be performed. After that, the anesthesia, rubber dam isolation and disinfection of the operating field with a 2% chlorhexidine solution are done. The complete removal of any remaining carious tissue must be performed, and the  

321 Protection of the Dentin-Pulp Complex

cavity irrigated with saline or calcium hydroxide solution. After that, the superficial curettage of the exposed pulp is done using a very sharp spoon excavator or a large diameter round diamond point, on high-speed handpiece and copious irrigation (. Fig.  9.22f) [68]. Then, an abundant irrigation with saline or calcium hydroxide solution is performed, and the walls and pulp tissue are dried with small sterile cotton pellets until the hemostasis is reached. When the bleeding  

stops, the characteristics of the remaining pulp tissue must be evaluated, and it must have a firm consistency and bright red color. Then, the corticosteroid/anti-inflammatory solution is applied for 10 min, and a new irrigation with saline or a calcium hydroxide solution is performed to remove the medication. The drying is performed with small sterile cotton pellet, and the material to stimulate the formation of the mineralized tissue is applied.

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..      Fig. 9.20  Direct pulp capping. a Initial aspect; b removal of the carious tissue; c accidental exposure of the distobuccal pulp horn; d materials necessary for the direct capping (1, Otosporin; 2, calcium hydroxide p.a.; 3, calcium hydroxide cement); e application of the association of corticosteroid/anti-inflammatory; f application of the calcium hydroxide powder using an MTA carrier (Angelus); g calcium

hydroxide p.a. applied over the exposed pulp; h application of the calcium hydroxide cement a little further than the area covered by the powder, closing the exposure area; i protection of the pulpal wall with glass ionomer cement; j acid etching; k application of the adhesive system; l restoration with composite resin (Grandio SO—Voco)

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..      Fig. 9.20 (continued)

Over the exposed area, a thin layer of the calcium hydroxide p.a. (powder or paste) or MTA is applied. The protector material must be inserted with no compression over the pulp tissue, and only over the exposed pulp surface, using an intraoral carrier (. Fig. 4.50b), and the excesses removed. Over this material, a layer of the calcium hydroxide cement is applied, covering the exposed area and a small region around it. Over the calcium hydroxide cement and the rest of the internal wall with deep dentin, a layer of GIC is placed, and the final restoration can be immediately done. Another option is to completely fill the preparation with GIC to follow up the pulp tissue response after the procedure. A period of 45–60  

days can be waited before the postoperative control. After this period, the pulp sensitivity testing to cold can be performed, as well a new radiographic examination to evince the status of the periapical area. The tooth must have no symptoms [63]. In the cases of pulp vitality, the absence of symptoms and periapical lesion, a superficial layer of the glass ionomer can be removed and the final restoration performed. 9.10.2.3  Pulpotomy

The pulpotomy consists of the removal of the inflamed coronary pulp tissue, maintaining the integrity of the radicular pulp. It is indicated on the tooth with incomplete root forma-

323 Protection of the Dentin-Pulp Complex

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..      Fig. 9.21  Direct pulp capping associated to the temporary restoration. a Accidental pulp exposure happened on the axial wall of the distal box during the tooth preparation; b after controlling the

bleeding, application of the calcium hydroxide p.a. over the area of the exposure; c application of the calcium hydroxide cement covering the entire axial wall; d temporary restoration with glass ionomer cement

tion in which the pulp remained exposed for more than 24 h. It is also indicated on teeth with large coronary destruction, but just on cases where there is no necessity to place an intracanal post [6]. In order to perform the pulpotomy, a good clinical and radiographic diagnosis is required. Some authors verified that the percentage of success of the pulpotomy (clinically and radiographically) was of 100% on young patients and 84% on adults [63]. The pulpotomy must be indicated only when there is no bone rarefaction on the periapical region or internal resorption and there is an integrity of lamina dura. In the clinical exam, the coronary pulp tissue will be considered macroscopically vital when it presents firm consistency, resistance to the  cut, followed by a  slight bleeding with bright red color, that stops in a few minutes after the cutting [95]. The pulpotomy may be performed on a single session (immediate technique) or in two sessions (delayed technique). For the immediate technique, the anamnesis, radiographic exam, and clinical diagnosis of the pulp condition are performed. Then, the anesthesia, rubber dam isolations, and the disinfection of the operating field with a 2% chlorhexidine solution must be done. The complete removal of the carious tissue, when there is any, is performed with round burs in a low-speed handpiece, and the opening of the pulpal

chamber is done  with diamond burs on high-speed handpiece. The cut of the coronary pulp tissue is performed with sterile and sharp dentin spoon excavator or a round diamond point on high-speed handpiece, with good refrigeration. The use of burs on low-speed must be avoided, because dentin shaves can be pressed over the pulpal tissue, interfering on the reparative process [96]. The bleeding must be controlled to allow the adequate contact between the protective material and the exposed pulp tissue. In order to do this, the irrigation of the cavity must be performed with saline or calcium hydroxide solution. Then the cavity must be dried with sterile small cotton pellets (. Fig. 9.23a–i). The antibiotics/anti-inflammatory solution (Otosporin or Maxitrol) is applied for 10 min over the pulp tissue with a small cotton pellet soaked with the medication. A new irrigation with saline or calcium hydroxide solution is performed to remove the medication, and the cavity is dried with a small sterile cotton pellet. Then, the pulp tissue must be covered by calcium hydroxide p.a. (powder or paste) or MTA. The protective material must be inserted without any compression over the exposed pulpal tissue, using an intraoral carrier, and the excess be removed. Over it the calcium hydroxide cement is applied covering the exposed area. The final restoration may be performed on the same session, followed by the  

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occlusal contact adjustment. If the final restoration is not performed in this same session, a temporary sealing of the cavity must be done with GIC, waiting for 45–60 days for the postoperative control. During the procedure, it is important to analyze the details of the remaining pulpal tissue. On teeth with several roots, there might be pulp with no conditions to be preserved in one or more roots, and it will contraindicate the pulpotomy. In this case, the conventional endodontic treatment will be the first choice.

In the delayed technique, immediately after the removal of the coronary pulp and the hemostasis, a piece of cotton soaked on an association of corticosteroids/antibiotics is placed over the pulp tissue for 48–72 h, which will be closed with a temporary restoration. This procedure is performed to reduce the inflammation caused by the cut of the pulp, reducing the increase of intrapulpal pressure, which could adversely affect the reparative process [6]. After this period, on the second session of treatment, the cotton pellet is

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f

..      Fig. 9.22  Pulp curettage. a, b Fracture of the tooth No. 21; c surgically open area to expose the fracture limits; d fragment removed showing the involvement of the pulp horn; e rubber dam isolation; f curettage of the superficial contaminated pulp with a diamond point; g application of the corticosteroid/anti-­inflammatory solution

(Otosporin, Glazo Smith Kline); h aspect of the pulp after curettage and hemostasis; i application of the calcium hydroxide p.a.; j covering of the region with calcium hydroxide cement; k finished restoration and suture; l aspect after 3 weeks

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g

h

i

j

k

l

..      Fig. 9.22 (continued)

removed, and the root pulp is covered with an adequate protector material, according to what is described on the immediate technique (. Fig. 9.24a–i). After pulpotomy, the tooth must be preferably restored at the same session. However, on the delayed pulpotomy technique, it is necessary to use a material for temporary restorative material. The GIC or RMGIC is the most indicated one for the temporary sealing. Between the sessions of treatment, it is very important that there is no displacement or fracture of the temporary restoration, which would allow the microleakage of microorganisms, leading to failure of the procedure.  

The postoperative follow-up must be performed at least for 2 years. Once the coronary pulp is removed, the sensitivity tests are not considered trustworthy for the evaluation of the pulp vitality. To determine the success, it is important to observe the absence of the signals and symptoms, as well the integrity of the lamina dura and the presence of a mineralized barrier or dentin bridge, although is  not always possible seen on radiography, besides the absence of a periapical lesion [6]. In the cases where the teeth have incomplete apex and the pulp is already on the initial phase of necrosis, apexification techniques must be applied.

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a

b

c

d

e

f

..      Fig. 9.23  Pulpectomy with the immediate technique. a Fracture of the tooth 21 resulted on a large pulp exposure on a tooth with an incomplete apex formation; b, c surgery to expose the region and rubber dam isolation; d curettage of the coronary pulp with the spherical diamond point; e irrigation with saline solution to promote

the bleeding control; f coronary pulp removed; g application of the calcium hydroxide p.a. over the pulpal tissue; h covering with the calcium hydroxide cement; i closing of the cavity with the glass ionomer cement

327 Protection of the Dentin-Pulp Complex

g

h

i

..      Fig. 9.23 (continued)

a

b

..      Fig. 9.24  Pulpectomy with the delayed technique. a–c Initial aspect of the fractured incisor with an incomplete apex formation. The pulp was exposed to contamination for more than a week. The coronary pulp was removed and a medication with corticosteroid/ anti-inflammatory association applied, remaining for 48 hours; d the coronary pulp on the second session; e application of the calcium hydroxide p.a.; f after 90 days, testing of the presence of the dentin

c

bridge with a gutta-percha cone; g formation of the dentin bridge clinically visible; h application of the calcium hydroxide cement over the dentin bridge; i filling of the cavity with a glass ionomer cement. (Images kindly supplied by Associate Prof. Carlos Henrique Ribeiro Camargo, Professor of the Endodontics, ICT, São José dos Campos – UNESP)

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d

e

f

g

h

i

..      Fig. 9.24 (continued)

Conclusion The aim of this chapter was to teach about materials, techniques, and principles currently available concerning the protection of the pulp-dentin complex. The histology and physiology of this complex was explained, as well the origins of pulpal alterations and the defense mechanisms. The methods to assess of pulp condition and create the diagnostic hypothesis were also presented. The knowledge about the cleaning and protective agents were presented, before

describing the different techniques and its indications. Due to the constant developments of materials and new scientific findings, some recommendations will certainly be changed in the next years. However, the search for the best technique should be kept in the dentist’s mind. The particularities of each human being must be considered by the clinicians, and the procedures should not be always standardized but be recommended according to the clinical conditions and particularities of each clinical case.

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110. Modena KC da S, Casas-Apayco LC, Atta MT, Costa CA de S, Hebling J, Sipert CR, et al. Cytotoxicity and biocompatibility of direct and indirect pulp capping materials. J Appl Oral Sci. 2009;17:544–54. https://doi.org/10.1590/S1678-­77572009000600002. 111. Mondelli J. Proteção do complexo dentinopulpar. São Paulo: Artes Médicas; 1998. 112. Mondelli J. Dentística operatória. 4th ed. São Paulo: Sarvier; 1979. 113. De Munck J, Van Meerbeek B, Yoshida Y, Inoue S, Vargas M, Suzuki K, et  al. Four-year water degradation of total-etch adhesives bonded to dentin. J Dent Res. 2003;82:136–40. https://doi. org/10.1177/154405910308200212. 114. Nagem FH. Adesão – adesividade em Odontologia. OdontoMaster – Estética. 1995;2:5–17. 115. Nagem Filho H, de Abreu Poletto LT, Vieira LC, Pereira JC. Chemical properties and biocompatibility of Ca(OH)2. Rev Odontol da Univ Sao Paulo. 1987;1:20–3. 116. Navarro MFL, Pascotto RC. Cimentos de ionômero de vidro. 1st ed. São Paulo: Artes Médicas: Série EAP-APCD; 1998. 117. van North R.  Introduction to dental materials. 4th ed. London: Mosby; 2007. 118. Orhan AI, Oz FT, Ozcelik B, Orhan K. A clinical and microbiological comparative study of deep carious lesion treatment in deciduous and young permanent molars. Clin Oral Investig. 2008;12:369–78. https://doi.org/10.1007/s00784-008-0208-6. 119. Pameijer CH, Wendt SL. Microleakage of “surface-sealing” materials. Am J Dent. 1995;8:43–6. 120. Parirokh M, Torabinejad M. Mineral trioxide aggregate: a comprehensive literature review-part III: clinical applications, drawbacks, and mechanism of action. J Endod. 2010;36:400–13. https://doi. org/10.1016/j.joen.2009.09.009. 121. Parirokh M, Torabinejad M. Mineral trioxide aggregate: a comprehensive literature review-part I: chemical, physical, and antibacterial properties. J Endod. 2010;36:16–27. https://doi.org/10.1016/j. joen.2009.09.006. 122. Pashley DH. Dynamics of the pulpo-dentin complex. Crit Rev Oral Biol Med. 1996;7:104–33. https://doi.org/10.1177/104544119600 70020101. 123. Pashley DH, Carvalho RM.  Dentine permeability and dentine adhesion. J Dent. 1997;25:355–72. https://doi.org/10.1016/ S0300-­5712(96)00057-7. 124. Pashley DH, Horner JA, Brewer PD. Interactions of conditioners on the dentin surface. Oper Dent. 1992;Suppl 5:137–50. 125. Perdigão J. Dentin bonding: variables related to the clinical situation and the substrate treatment. Dent Mat. 2010;26:e24–37. 126. Perdigão J, Denehy GE, Swift EJ. Effects of chlorhexidine on dentin surfaces and shear bond strengths. Am J Dent. 1994;7:81–4. 127. Pereira JC, Berbert A, Segala AD.  Long term clinical and radiographic evaluation of teet submitted to indirect pulp capping. J Dent Res. 1997;76(Spec. I):Abstract n. 1328. 128. Pereira JC, Furuse AY, Benetti AR, Hannas AR, Canova GC, Costa LC, et al. Proteção do complexo dentinopulpar. In: Busato AL, editor. Dentística Filos Conceitos e prática clínica. São Paulo: Artes Médicas; 2005. p. 147–201. 129. Pereira JC, Manfio AP, Franco EB, Lopes ES. Clinical evaluation of Dycal under amalgam restorations. Am J Dent. 1990;3:67–70. 130. Pesce HF, Medeiros JMF, Capriglione V, Santos M.  Avaliação do teste elétrico pulpar quando alicado nos diferentes grupos dentais. Odontol Mod. 1990;17:7–9. 131. Peters DD, Augsburger RA. In vitro cold transference of bases and restorations. J Am Dent Assoc. 1981;102:642–6. 132. Petersson K, Soderstrom C, Kiani-Anaraki M, Levy G. Evaluation of the ability of thermal and electrical tests to register pulp vitality. Endod Dent Traumatol. 1999;15:127–31. 133. Powis DR, Folleras T, Merson SA, Wilson AD. Improved adhesion of a glass ionomer cement to dentin and enamel. J Dent Res. 1982;61:1416–22. 134. Reston EG, de Souza Costa CA.  Scanning electron microscopy evaluation of the hard tissue barrier after pulp capping with cal-

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Biomed Mater Res – Part B Appl Biomater. 2007;81:175–84. https:// doi.org/10.1002/jbm.b.30651. 155. Sowden JA. A preliminary report on the recalcification of carious dentin. J Dent Child. 1956;23:187–8. 156. Stanley HR.  Human pulp response to restorative dental procedures. 2nd ed. Florida: Starter Printing; 1981. 157. Stanley HR, Pereira JC, Spiegel E, Broom C, Schultz M. The detection and prevalence of reactive and physiologic sclerotic dentin, reparative dentin and dead tracts beneath various types of dental lesions according to tooth surface and age. J Oral Pathol. 1983;12:257–89. 158. Stanley HR, White CL, McCray L. The rate of tertiary (reparative) dentine formation in the human tooth. Oral Surg Oral Med Oral Pathol. 1966;21:180–9. 159. Taira M, Wakasa K, Yamaki M, Matsui A. Heat generated when cutting natural tooth enamel, composite resin model tooth enamel and glass-ceramic Typodont tooth. Hiroshima Daigaku Shigaku Zasshi. 1990;22:210–2. 160. Tam LE, Pulver E, McComb D, Smith DC. Physical properties of calcium hydroxide and glass-ionomer base and lining materials. Dent Mater. 1989;5:145–9. https://doi.org/10.1016/0109­5641(89)90001-8. 161. Tay FR, Gwinnett AJ, Pang KM, Wei SH.  Structural evidence of a sealed tissue interface with a total-etch wet-bonding technique in vivo. J Dent Res. 1994;73:629–36. 162. Thompson VT, Craig RG, Curro FA, Green WS, Ship JA. Treatment of deep carious lesions by complete excavation or partial removal. J Am Dent Assoc. 2008;139:705–12. https://doi.org/10.14219/jada. archive.2008.0252. 163. Torabinejad M, Hong C, MC Donald F, Pittford T. Physical and chemical properties of a new root-end filling material. J Endod. 1995;21:349–53. https://doi.org/10.1016/S0099-2399(06)80967-2. 164. Torabinejad M, Chivian N. Clinical applications of mineral trioxide aggregate. J Endod. 1999;25:197–205. https://doi.org/10.1016/ S0099-2399(99)80142-3. 165. Torabinejad M, Parirokh M. Mineral trioxide aggregate: a comprehensive literature review—part II: leakage and biocompatibility investigations. J Endod. 2010;36:190–202. https://doi. org/10.1016/j.joen.2009.09.010. 166. Torres CRG, Carvalho JC, Valera MC, Araújo MAM. Materiais ósseoindutores para o complexo dentino pulpar. Rev Fac Odontol São José dos Campos. 2000;3:88–96. 167. Trowbridge HO.  Pathogenesis of pulpitis resulting from dental caries. J Endod. 1981;7:52–60. 168. Trowbridge HO, Kim S. Pulp development, structure and function. In: Cohen S, Burns RC, editors. Pathways pulp. 6th ed. St. Louis: Mosby; 1994. p. 296–336. 169. Tuna D, Ölmez A. Clinical long-term evaluation of MTA as a direct pulp capping material in primary teeth. Int Endod J. 2008;41:273– 8. https://doi.org/10.1111/j.1365-2591.2007.01339.x. 170. Tziafas D, Alvanou A, Panagiotakopoulos N, Smith AJ, Lesot H, Komnenou A, et al. Induction of odontoblast-like cell differentiation in dog dental pulps after in  vivo implantation of dentine matrix components. Arch Oral Biol. 1995;40:883–93. https://doi. org/10.1016/0003-9969(95)00069-2. 171. Tziafas D, Belibasakis G, Veis A, Papadimitriou S.  Dentin regeneration in vital pulp therapy: design principles. Adv Dent Res. 2001;15:96–100. https://doi.org/10.1177/089593740101500125 01. 172. Tziafas D, Smith A, Lesot H. Designing new treatment strategies in vital pulp therapy. J Dent. 2000;28:77–92. https://doi.org/10.1016/ S0300-5712(99)00047-0. 173. Tziafas D. Experimental bacterial anachoresis in dog dental pulps capped with calcium hydroxide. J Endod. 1989;15:591–5. https:// doi.org/10.1016/S0099-2399(89)80157-8. 174. Uribe Echevarria JU. Operatoria dental: Ciencia y pratica. Madrid: Avances Medico-dentales; 1990.

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175. Vieira DF, Mondelli J. Fracture strength of class II amalgam restorations condensed over protective bases. J Prosthet Dent. 1973;30:166–72. 176. Weine FS.  Tratamento endodôntico. 5th ed. São Paulo: Editora Santos; 1998. 177. Weisleder R, Yamauchi S, Caplan DJ, Trope M, Teixeira FB. The validity of pulp testing. A Clinical Study J Am Dent Assoc. 2009;140:1013– 7. https://doi.org/10.14219/jada.archive.2009.0312.

178. Weyne S. Cariologia, a cárie como uma doença infecciosa e transmissível. In: Baratieri LN, editor. Dentística – procedimentos Prev e restauradores. 3rd ed. Rio de Janeiro: Santos; 1990. p. 1–42. 179. Yap AU, Shah KC, Loh ET, Sim SS, Tan CC.  Influence of eugenol-­ containing temporary restorations on bond strength of composite to dentin. Oper Dent. 2001;26:556–61. 180. Zach L, Cohen G.  Pulp response to externally applied heat. Oral Surg Oral Med Oral Pathol. 1965;19:515–30.

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Introduction – 336

10.2

Instruments and Materials – 336

10.3

Previous Procedures – 336

10.4

Class I or Site 1 Preparations – 338

10.4.1 10.4.2

S imple Preparation – 338 Compound Preparation – 344

10.5

Class II or Site 2 Preparations – 350

10.5.1 10.5.2

 ccess Through the Occlusal Surface – 359 A Access Through the Buccal or Lingual Surfaces – 363

10.6

Class V or Site 3 on Free Smooth Surface – 365

10.6.1 10.6.2 10.6.3 10.6.4 10.6.5 10.6.6 10.6.7 10.6.8

 utline Form – 366 O Resistance Form – 368 Retention Form – 368 Convenience Form – 369 Removal of the Remaining Carious Tissue – 370 Finishing the Enamel Walls – 370 Cleaning of the Preparation – 370 Final Characteristics of the Preparation – 370

References – 370

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Learning Objectives The learning objectives of this chapter are related to the following topics: 55 The instruments and materials necessary to perform a tooth preparation for amalgam. 55 The previous procedures that must be performed before starting. 55 The steps for Class I preparations of simple and complex cavities. 55 The steps for Class II preparations by access through the occlusal or free smooth surfaces. 55 The steps for Class V preparation on smooth surfaces. 55 The final characteristics of all kinds of preparation for amalgam.

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10.2  Instruments and Materials

To perform a tooth preparation for amalgam restoration in preclinical dental training, the following materials and instruments are necessary: 55 Personal protective equipment such as gloves, mask, mob cap, and safety glasses. 55 Dental training model with simulations of the carious lesions to be placed inside a dental simulator phantom. 55 Low-speed handpiece and contra-angle. Although most dental procedures are performed in the real patient with the high-speed handpiece, the initial training with dental models should be performed in low speed, until the students develop the manual skills and have complete mastery of the technique. 55 Dental tweezer. 10.1  Introduction 55 Flat first surface clinical mirror. 55 Double exploratory probe. The dental amalgam is a restorative material that has been 55 Rotary instruments for low-speed contra-angle (RA/CA) used for a long time to restore teeth affected by the caries or for high-speed handpiece (FG) with an adaptor for disease. Although there is a huge discussion about its use the contra-angle. It can be used the carbide or diamond nowadays due to the presence of the mercury and the unfapoints (. Fig. 10.1). Those instruments are identified by vorable esthetics, it is still largely used around the world to the shape of the head. restore posterior teeth, especially because of its versatility, 55Round – No. 1011 diamond point or No. 2, 4, and 6 low cost, and excellent physical properties, resulting to high-­ carbide burs quality and long-lasting restoration. As a great disadvantage, 55 Long inverted cone with flat end and round corners – this material does not bond to the tooth structure, being necNo. 1148 and 1150 diamond point or No. 245 carbide bur essary that some specific characteristics are observed during 55Short inverted cone with flat and sharp edges – No. the preparation, allowing that remaining tooth structure and 1031 diamond point or No. 33 ½ carbide bur restoration may resist to the masticatory stress. On this chap55Cylinder with flat end and round corners – No. ter, the necessary steps to make the tooth preparation for 1090A and 1092A diamond points amalgam restoration are presented, in a way to allow the 55Conical with flat end – No. 1061 and 1063 diamond reader to be able to perform this procedure. During the inipoint or No.169 carbide bur tial training of the dental students, all the stages of the tooth 55 Enamel hatchet – 14/15 (10-6-14). preparation should be performed on dental training model 55 Gingival margin trimmers – 28 (10-95-7-14) and 29 with simulations of the carious lesions. The use of dental (10-80-7-14). models without the lesion simulation, with intact teeth, 55 Miller articulating paper forceps. induces the student to learn stereotyped forms for the tooth 55 Thin double-sided articulating paper (> The bur must penetrate the structure while spinning, and it should not stop until it is removed away from any contact with the tooth. However, the handpiece should never go in or out the patient’s oral cavity with the bur still rotating.

After the cavity opening, the outline of the preparation can be defined. The basic principle to be considered is the maximum preservation of the remaining tooth structure. In the past, the width of the preparation in the buccolingual direction was standardized, defined by calculating 1/3 of the dis-

339 Tooth Preparations for Amalgam Restorations

tance between the tips of the cusps, which led to a considerably weakening of the tooth, with reduction of approximately 33% of its fracture resistance. More recently, this standard was reduced to 1/4 of the distance between the tips of the cusps, with a smaller reduction of the tooth resistance [27]. However, nowadays, the extension for prevention is no longer recommended, as well as no stereotyped outlines must be followed. Therefore, only the area affected by the carious lesion

is included in the preparation [11, 20]. The margins are cut until they reach intact enamel, even though it is undermined. The undermined enamel can be later reinforced with artificial dentin, using glass ionomer cements. Other factor that determines the width of the preparation is the need to obtain enough access to perform the restoration. Therefore, even in a very small lesion, the outline must have the minimum size that allows the use of the smaller

a

b

c

d

e

f

..      Fig. 10.4  Class I or Site 1 tooth preparation on a mandibular molar. a Marking the contacts with articulating paper; b opening of the cavity with the round diamond point perpendicular to the occlusal surface; c opening with a long inverted cone point leaned in relation to the occlusal surface; d–f penetration of half head of the No. 1148 rotary

instrument and delimitation of the outline shape; g analysis of the preparation walls to evaluate for the presence of remaining carious tissue (arrows); h modification of the outline to remove the affected areas; i final aspect

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g

h

i

10

..      Fig. 10.4 (continued)

amalgam condenser available, which can be considered a convenience form [12]. When preparing tooth with small lesions, the opening is started with the smallest rotary instrument available [22]. The conservative preparation minimizes the pulp response and keeps the resistance of the remaining tooth structure, reducing the chances of cuspal fracture [8, 12, 20]. In addition, narrow restorations, generally smaller than 1 mm, present less marginal fractures and ditching than the large ones, reducing the need of replacement later on [20, 23]. This happens due to the fact that the small occlusal isthmus usually locates the preparation margins far from the contact areas with the opposite tooth, which allows contacts occur over the remaining tooth structure [2, 7, 23]. In addition, the smaller restorations are better condensed due to the use of small pluggers, which produce a greater condensation pressure, removing more mercury and improving the adaptation of the restorative material [20]. According to Almquist et al. [2], if the patient is taught to completely clean his teeth, it is not necessary to extend the preparation margins more than the necessary to give it an adequate form. Any restoration that can be correctly polished by the dentist can be properly cleaned by the patient. If the patient does not clean his teeth, it does not matter the amount of extension for prevention performed because it will not be capable to prevent additional carious lesions and eventually the total destruction of the tooth.

On the posterior teeth, the inclines of adjacent cusps are separated by developmental grooves, which represent lines of union between lobes of the crown during its formation. The enamel of both lobes, on the bottom of the groove, may have been perfectly connected during the tooth formation or a linear fault may sometimes have happened creating a fissure, which represents a lack of union between the cups inclines. This fissure directly connects the oral environment to the dentin on the dentinoenamel junction (DEJ) area. Even though the carious lesion generally begins at an occlusal fissure, it is frequently isolated in only one place or few places along the extension of the groove. It rarely happens on the entire groove. When there are lesions in fissures which are not connected, separated by areas of intact groove, individual preparations must be performed, without the need to connect them, unless there is less than 0.5  mm between the preparations (. Fig. 6.24a–c) [22]. After the preparations are completed, if necessary, the areas of the groove not affected by carious lesion but highly susceptible to caries can be protected with a pit and fissure sealant [20]. As a general rule, the larger the restoration, the less it will last [20]. If the preparation is conservative, size 1 or 2 according to Mount and Hume [18], the No. 1148 or No. 1150 diamond point or the No. 245 bur, with a long-inverted cone shape should be used (. Fig.  10.1). With these instruments, the vertical surrounding walls will be slightly convergent toward  

 

341 Tooth Preparations for Amalgam Restorations

a

b

c

d

e

f

..      Fig. 10.5  Class I or Site 1 preparation on the mandibular first premolar. a Demarcation of the contact points; b opening the preparation with a round diamond point; c positioning of the diamond point perpendicular to the plane that tangents the tips of the cusps;

d delimitation of the preparation outline; e aspect of the surrounding walls convergent towards the occlusal surface, due to the use of the inverted conical- trunk instrument; f final aspect of the tooth preparation

the occlusal surface. If the preparation is large, No. 3 or 4 bur or No. 1090A or No. 1092A diamond point, with cylinder shape and round corners should be used (. Fig. 10.1). With these instruments, the vertical surrounding walls will be parallel to each other [11, 12]. At the moment of the outline form of the preparation, the penetration of the rotary instrument is restricted to about 0.2–0.5 mm [12, 16] further than the DEJ, which will create a preparation with about 1.5 mm deep on the central groove, or 2 mm in relation to the buccal or lingual cavosurface angle [22]. It is considered as a refer-

ence area for the depth of the preparation the deepest area of the central groove. Consequently, outside this area, the surrounding vertical walls will have a greater height, allowing a greater thickness of the restorative material. It is possible to use the head length of a bur or diamond point as a reference for the preparation depth evaluation [22]. The No. 1148 diamond point and the No. 245 bur heads have a length of 3 mm. Therefore, the penetration of half its length into the tooth structure will create the minimal necessary depth for an amalgam preparation (. Fig.  10.4d–f). When using the

 

 

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No. 1150, 1090A, or 1092A diamond points, which have the head length of 4 mm, the use of half this length will also provide a satisfactory reference value. After penetrating the necessary depth into the carious lesion, the rotary instrument should be moved on the mesiodistal direction, with its long axis parallel to the long axis of the tooth, maintaining a uniform preparation depth. At this step, the preparation depth is maintained, even though old restorative material or carious tissue remains on the pulpal wall, because they will be removed during the final phase of the preparation. On the other hand, the cavosurface angles of the vertical surrounding walls must reach sound enamel (. Fig.  10.4g, h). After this step, the occlusal contacts with the antagonist tooth are analyzed, checking if it will not be located at the interface between the tooth and the future restoration. In this case, the outline must be changed through an additional cut of wall in this area, positioning the contact over the restorative ­material.  

10.4.1.2  Resistance Form

10

To improve the resistance of preparation and restoration, the walls must be flat, uniform, and smooth, improving the adaptation of the restorative material. The flattening and the smoothness of the walls can be obtained moving the rotary instrument to and fro [13]. The depth of the preparation should allow a minimum depth of 1.5 mm for the amalgam on the contact area or at the center of the restoration, in the region of the central groove [12]. The pulpal wall is flat, which is obtained through the flat tip of the rotary instrument’s head [12]. The flat pulpal wall allows a better distribution of the stress and prevents the rotation of the restoration (. Fig. 6.28a–c). On most of the posterior teeth, the pulpal wall must be parallel to the occlusal plane of the dental arch, making it perpendicular to the direction of the occlusal loads. To perform that, the long axis of the rotary instrument is positioned parallel to the long axis of the tooth (. Fig. 10.6a). One exception to this rule is the mandibular first premolar, where there is a large difference on the volume of the buccal and lingual cusps. That creates the need that the pulpal wall should be prepared parallel to the plane  

 

a

touching the tip of both cusps, avoiding the exposure of the buccal pulp horn, besides preserving the dentin under the lingual cusps (. Fig. 6.14a, b). For that, the rotary instrument is positioned perpendicular to the intercuspal plane (. Fig. 10.5c, d). The resistance form is also obtained with the use of rotary instruments with round corners, which creates round internal line angles of the second set, and allows a better distribution of the stress, reducing the probability of fracture of the remaining tooth structure (. Fig. 6.39) [2, 12, 23]. This is particularly important on the cases of large preparations, where the tooth structure is fragile [11, 16]. In addition, the round angles allow a better adaptation of the restorative material [2, 23]. The use of traditional No. 56 or No. 57 straight fissure or No. 1090 and No. 1092 cylinder diamond points, even though create parallel vertical surrounding walls, also produce sharp internal line angles of the second set, which concentrate the stress in the angle area of the remaining tooth structure, exactly on the cases where this detail is more relevant, such as the large lesions. In relation to the restoration margins, the resistance form is obtained first by avoiding the contact of the antagonist tooth on the tooth restoration interface, protecting it from the occlusal loads [12]. Second, the resistance can also be improved by the convergence of the buccal and lingual walls toward the occlusal surface, which create a greater marginal angle of the restoration, at least 70° [12, 13]. This greater thickness of the restorative material on the restoration margins decreases its marginal degradation. However, on large cavities, the preparation of parallel surrounding vertical walls is more favorable because of the use of the convergent walls may weaken even more the already fragile structure (. Fig. 6.36a, b). During the preparation, it is extremely important to evaluate if the long axis of the rotary instrument is properly positioned, perpendicular to the occlusal plane. Otherwise, in one of the sides of the preparation, there will be undermined enamel susceptible to fracture, while on the other side there will be a thin margin of the restorative material and more chances of pulp exposure (. Fig. 10.6a, b) [26].  

 

 

 

 

b

..      Fig. 10.6  Direction of the resulting walls in relation of the leaning of the rotary instrument. a Correct; b incorrect

343 Tooth Preparations for Amalgam Restorations

a

b

..      Fig. 10.7  a Evaluation of the marginal ridge remaining using as a reference the No. 1048 diamond point; b preparation of the proximal walls slightly expulsive towards the occlusal surface

a

b

..      Fig. 10.8  Additional retention on the base of the cusps. a Position of the rotary instrument during the preparation, b retention test with an exploratory probe

To preserve the resistance of the remaining tooth structure on large cavities, the mesial and distal walls in contact with the marginal ridge should be slightly expulsive toward the occlusal surface [12, 13, 16, 25]. This avoids that the remaining dentin under the ridge is removed (. Fig. 6.41a–f) [25]. This characteristic is obtained leaning the rotary instrument toward the proximal surface in more or less 10° (. Fig. 10.7b) [22]. Although the resistance of the remaining tooth structure is preserved, this inclination produces thin margins for the restoration, with a greater chance of fracture [16]. On the other hand, on smaller preparations, where the marginal ridge has more than 1.6 mm of thickness in premolars or 2 mm in molars, those walls can be convergent toward the occlusal surface [3, 22]. It is possible to have an idea about the thickness of the marginal ridge using the diameter of the rotary instrument head as a reference (. Fig. 10.7a) [22]. On cases of teeth with oblique enamel ridges, as the maxillary molars, or the transverse ridge on the first mandibular premolars, it is important its maximum preservation to keep the resistance of the remaining tooth structure [13]. The resistance of the tooth structures is greater than of amalgam.  

 

 

10.4.1.3  Retention Form

The retention of the restorations is obtained by the convergence of the buccal and lingual walls when a long-inverted cone-shaped rotary instrument is used. It is also achieved when the preparation is deeper than wide when using a cylinder rotary instrument. When the walls are prepared parallel to each other and the buccolingual dimensions of the preparation are wider than the depth, additional mechanical retention must be prepared. Small coves are made under the cusps, which are the areas with larger volume of dentin (. Fig. 10.8a, b) [12]. For that, an inverted cone instrument is used, such as No. 1031 diamond point or No. 33 ½ bur. A small round instrument can also be used, such as No. ½ or the No. 1011 diamond point (. Fig. 10.1) [3]. According to Sturdevant [22], the retentions performed with round instruments are better than the ones prepared with the inverted cone, because the amalgam can be better condensed on round than on sharp areas, resulting on a better adaptation of the restorative material. The cut must be performed exclusively on the buccal or lingual walls (. Fig. 6.44a, b). The retention can be tested by pressing the tip of an explor 

 

 

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atory probe inside the cove and simultaneously pulling toward the occlusal surface (. Fig. 10.8b) [16]. On the cases where a cavity liner or base is applied, the additional retentions are prepared only after the walls have been filled with that material [3].  

10.4.1.4  Convenience Form

In relation to the Class I preparation, the convenience form is limited to the cases of small lesions. On this situation, the fitting of the smallest amalgam condenser instrument inside the preparation must be evaluated, allowing an adequate condensation of the restorative material. If the contour of the preparation is too small, it must be slightly enlarged, only enough to allow an adequate restoration. 10.4.1.5  Removal of the Remaining Carious

Tissue

10

At this moment, in cases of small lesions, the entire carious tissue was already removed. In larger lesions, if some highly infected dentin tissue remained in any region, it can be removed with a round bur at low speed, of larger size compatible with the preparation contour, or with a spoon excavator. Those regions with irregular walls can later be flattened with the application of a base material, and the undermined enamel be reinforced with GIC (. Fig. 6.6a–d).  

10.4.1.8  Final Characteristics

of the Preparation Small- and Medium-Size Preparations (Sizes 1 and 2) 55 Flat, uniform, and smooth walls 55 Buccal and lingual walls slightly convergent toward the occlusal surface 55 Mesial and distal walls in contact with the marginal ridge slightly expulsive toward the occlusal surface, when there is little remaining of the ridge, or convergent toward the occlusal surface, when there is a large marginal ridge remaining 55 Round internal line angles of the first and second sets 55 Walls in contact with the oblique enamel ridges, in the maxillary molars, or the transverse ridge on the first mandibular premolars, convergent toward the occlusal surface

Large Cavities (Size 3 and 4) 55 Flat, uniform, and smooth walls 55 Buccal and lingual walls parallel to each other 55 Mesial and distal walls in contact with the marginal ridges expulsive toward the occlusal surface 55 Round internal line angles of the first and second sets 55 Walls in contact with the oblique enamel ridges, in the maxillary molars, or the transverse ridge on the first mandibular premolars parallel to each other

10.4.1.6  Finishing the Enamel Walls

The smoothness of the preparation wall margins allows removal of the undermined enamel susceptible to fractures [12]. However, on this type of preparation, the use of correctly positioned rotary instruments will by itself create a smooth surface, without undermined enamel prisms at the margins. Therefore, no additional procedures would be necessary. The final evaluation of the preparation is done with an exploratory probe, to analyze if there is any residual carious tissue, the shape of the walls is correct, and the enamel margins are supported by natural or artificial dentin [12]. 10.4.1.7  Cleaning of the Preparation

The preparation is cleaned with air and water spray and then receives the application of an anionic detergent, with a small cotton pellet or a disposable applicator, followed by washing with water and drying with air stream [22]. After that, the disinfection of the preparation can be performed with a chlorhexidine solution followed only by drying [22]. Another option is to apply a 2% neutral sodium fluoride solution for 2–4 min, followed by drying. This procedure will promote the deposition of calcium fluoride over the preparation walls, acting as a fluoride reservoir that will be release if there is a drop of pH [3]. The application of the fluoride solution can reduce up to 60% of the formation of secondary caries on the amalgam restoration margins and interface [1].

10.4.2  Compound Preparation

For illustrative purposes, the details about the preparation will be presented on the tooth 26. However, the same principles can be applied on other similar situation such as on the mandibular molars (. Fig. 10.9a–r).  

10.4.2.1  Outline Form

A round diamond point or carbide bur, with its long axis positioned perpendicularly to the occlusal plane, or a cylinder or long-inverted cone diamond point or carbide bur, leaning to the mesiodistal direction, can be used to open the cavity (. Fig.  10.9b). On the maxillary and mandibular molars, where both the occlusal and the buccal or lingual surfaces were involved by the caries lesion, the outline form of the preparation may be variable, as it can be observed in . Fig. 10.10a–d. The occlusal cavity may connect to the buccal or lingual cavity, or they might stay as two independent simple cavities. The outline must be the most conservative possible but enough to remove the entire carious tissue until it reaches intact enamel [22]. The depth of penetration is restricted to 0.2–0.5  mm beyond the DEJ on the region of the central groove. The preparation starts by delimitation of the occlusal outline, with a rotary instrument parallel to the long axis of the tooth, maintaining a constant depth and coming closer to the groove of the smooth surface (. Fig. 10.9c–e) [22]. Then,  

 

 

345 Tooth Preparations for Amalgam Restorations

the rotary instrument is inserted on the region of the lingual groove, with its long axis parallel to the surface, in a depth of approximately 0.75 mm (. Fig. 10.9f) [22]. Considering that the No. 1148 and No. 1090A diamond points have 0.8 mm of diameter, it is possible to know that the preparation has the minimum necessary depth when the instrument has penetrated almost completely on the tooth structure (. Fig. 10.9g).  

 

10.4.2.2  Resistance Form

The walls must be flat, uniform, and smooth to improve the stress distribution and adaptation of the restorative material. The minimal depth is 1.5  mm on the region of the central groove and 0.75 mm on the smooth surface to give resistance to the restoration. The pulpal wall must be parallel to the occlusal plane [19]. On small or medium preparations (Sizes

a

b

c

d

e

f

..      Fig. 10.9  Class I or site 1 compound preparation on a maxillary molar. a Marking of the contact points; b opening the cavity with a round diamond point; c, d preparation of the occlusal part of the groove with the long-inverted cone diamond point. e Finished occlusal box; f–g lingual groove preparation with the long axis of the diamond point parallel to the surface lingual; h analysis the preparation to verify the presence of remaining carious tissue; i, j removal of the remaining

carious tissue; k filling of the region with the GIC as a base material; l preparation of the mesioaxial line angle with the diamond point perpendicular to the axial wall. m preparation of the distoaxial line angle; n, o rounding of the axiopulpal angle with the tip of the diamond point or with a gingival margin trimmer. p trimming of the gingival cavosurface angle with a gingival margin trimmer; q, r final aspect of the tooth preparation

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g

h

i

j

k

l

m

n

10

..      Fig. 10.9 (continued)

347 Tooth Preparations for Amalgam Restorations

o

p

q

r

..      Fig. 10.9 (continued)

1 and 2), the surrounding walls of the occlusal box are convergent toward the occlusal surface to increase the thickness of the restoration margin, improving its resistance [22]. For that, a No. 1148 or No. 1150 inverted cone diamond point or a No. 245 bur must be used. If the marginal ridge is too fragile, the wall that is in contact with it must be expulsive toward the occlusal surface. On large cavities (Size 3 and 4), the surrounding walls of the occlusal box are left parallel among each other. For that, the No. 1090A or No. 1092A cylinder diamond points are used. The distal walls of the occlusal box, in contact with the marginal ridge, have to be expulsive toward the occlusal surface to preserve its dentin support [22]. The internal line angles of the second set are round, which can be achieved when using the described rotary instruments. The axial wall must be expulsive toward the occlusal surface, in a way to follow the leaning of the lingual surface and allow a homogeneous thickness of the restorative material, increasing the final resistance of the restoration. This is achieved positioning the long axis of the rotary instrument parallel to the lingual surface on the buccolingual direction, penetrating about 0.2–0.5  mm further than the DEJ or enough so that the carious tissue is removed and a minimum thickness of the restorative material is obtained (. Fig. 10.9f, g) [22]. The tip of the bur must be positioned at the end of the lesion creating the gingival wall, with the internal line angles  

of the first set round. The dentist must keep a good control of the rotary instrument and not let it roll outside the preparation, over the lingual surface, which may damage the cavosurface margin [22]. When a No. 1148 or No. 1150 long-inverted cone diamond point or a No. 245 bur is used for the preparation of the lingual box, the mesial and distal walls will be slightly convergent toward the occlusal and lingual surfaces (. Fig. 10.9r) [22]. If a cylinder instrument is used, those walls will be parallel to each other. To better define the mesoaxial and axiodistal angles, the long-inverted cone or cylinder rotary instrument is positioned with its long axis perpendicular to the lingual surface, with the tip touching the axial wall, and moved in the occluso-cervical direction [22], without changing the axial wall (. Fig. 10.9l, m). If a long-inverted cone point or burs are used, the mesial and distal walls will be retentive toward the lingual surface, while if cylinder instruments are used, they will be parallel between each other [22]. The gingival wall must be parallel to the pulpal wall and the occlusal plane, allowing the distribution of the occlusal loads because they are perpendicular to the direction of the load [19]. This is obtained by positioning the bur parallel to the long axis of the tooth. The internal angles are round, which is automatically obtained due to the round corners of the rotary instrument heads, with the exception of the axiopulpal angle. This must be rounded with a No. 29 gingi 

 

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..      Fig. 10.10  Variations on the preparation outline due to the extension of the lesion on the maxillary and mandibular molars. a, c Preparation outline when the lesions extend on the entire groove of the smooth surface; b, d preparation outline when the lesion is restricted to the pits on the smooth surfaces. The occlusal and buccal/lingual boxes should not be connected

a

b

c

d

10

val margin trimmer, moved in the mesiodistal direction, or with the flat tip of a rotary instrument adequately positioned (. Fig. 10.9n, o) [15].  

10.4.2.3  Retention Form

On the occlusal box, the retention is obtained by the convergence of the surrounding walls toward the occlusal surface. When the walls are created parallel to each other and the cavity is wider than the deep, additional retention like a cove can be made under the distobuccal cusp, as it was described for the simple cavity (. Fig. 10.11a, b). On the lingual box, when the inverted cone instrument is used, the cavity is self-­ retentive toward the occlusal and lingual surfaces [22]. When the cylinder bur is used, the parallelism of the mesial and distal walls already creates retention toward the occlusal surface. However, it can be not enough on the lingual direction, especially if the occlusal box is shallow and little retentive on this direction. On this case, the additional mechanical retentions can be created through the retention locks on the mesioaxial and distoaxial line angles, on the dentin of the mesial and distal walls, but never on the enamel [22]. Those retentions may be created with a conic instrument, such as the No. 1061 diamond point or No. 169 bur, or a round

instrument such as the No.1011 diamond point or the No. ½ bur. When a conical rotary instrument is used, it is leaned to the mesiodistal direction so that the tip first touches the region next to the mesiogingival or distogingival angles, resulting on the pyramid-shaped retention and not surpass the axiopulpal angle (. Fig. 10.11c–e) [22]. The retention is tested inserting the tip of an exploratory probe and moving it toward the lingual surface [22]. The retention must hinder the probe to directly move toward the lingual surface (. Fig. 10.11f) [22].  

 

 

Tip

Additional mechanical retentions must be always prepared on dentin tissue and never on enamel or close do DEJ.

10.4.2.4  Convenience Form

It is restricted at this preparation the necessary width so that the smaller condenser instrument may reach the deepest areas near to the internal walls.

10

349 Tooth Preparations for Amalgam Restorations

a

b

c

d

e

f

..      Fig. 10.11  Preparation of additional retentions. a, b Preparation of retention on the occlusal box; c–e preparation of retentions on the lingual box, on the mesioaxial, and on the distoaxial line angles; f retention test

10.4.2.5  Removal of the Remaining Carious

Tissue

In general, at this phase of the preparation, no more carious tissue probably remained. However, if there is any, it can be removed as it has already been described for the simple cavity, and the undermined enamel area filled with GIC (. Fig. 10.9h–k).  

10.4.2.6  Finishing the Enamel Walls

The undermined enamel at the region of the gingival cavosurface angle is trimmed with a No. 29 gingival margin trimmer, by moving it to the mesiodistal direction (. Fig. 10.9p).  

10.4.2.7  Cleaning of the Preparation

It is performed as it has already been described for the simple cavity.

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10.4.2.8  Final Characteristics

of the Preparation Small- and Medium-Size Preparations (Sizes 1 and 2) 55 Flat, uniform, and smooth walls 55 Buccal and lingual walls slightly convergent toward the occlusal surface 55 Mesial wall in contact with the oblique enamel ridge convergent toward the occlusal surface 55 Distal wall in contact with the marginal ridge convergent toward the occlusal surface 55 Internal line angles of the first and second sets and external line angle round 55 Mesial and distal walls of the lingual box convergent toward the occlusal and lingual surfaces

Large-Size Preparation (Sizes 3 and 4)

10

55 Flat, uniform, and smooth walls 55 Buccal and lingual walls parallel to each other 55 Mesial wall in contact with the oblique enamel ridge perpendicular to the pulpal wall 55 Distal wall in contact with the marginal ridge expulsive toward the occlusal surface 55 Internal line angles of the first and second sets and external line angle round

a

..      Fig. 10.12  Vertical slot tooth preparation. a Marking of the contact points; b proximal view of the lesion; c separated preparation of the occlusal lesions; d access to the lesion through an opening in the marginal ridge using a round diamond point; e the dentist feels a sensation to fall on an empty space when reaching the lesion; f cavity opened allowing access to the lesion. g, h penetration of the inverted cone point, which is moved in the buccolingual direction and toward the marginal ridge; i marginal ridge remaining; j–l fracture of the ridge with an excavator spoon; m, n outline of the walls with the pendulum motion on the buccolingual direction. o occlusal aspect after the

55 Mesial and distal walls of the lingual box parallel to each other 55 Additional retention of the mesioaxial and distoaxial line angles 10.5  Class II or Site 2 Preparations

This type of cavity involves the proximal surfaces of the posterior teeth, where the caries lesions are located below the contact point. When there are no carious lesions on the occlusal surface, or when the occlusal lesion is far from the marginal ridges, the preparation of the proximal area can be independent from the occlusal preparation. The access to the proximal lesion is performed in the marginal ridge, and this kind of preparation is called proximal box preparation or vertical slot preparation (. Fig. 10.12). If the occlusal surface has also been affected  by the lesion and reaches the proximal lesion, the preparation of the occlusal surface is connected to the proximal one, resulting to mesio occlusal, occluso distal, or mesio occlusodistal preparations (. Fig.  10.13). When the caries lesion is too far from the occlusal surface, such as on the cases of teeth with long clinical crowns or on teeth with gingival recession, with the carious lesion at the CEJ, the access can be performed from the buccal or lingual surfaces, and the preparation is called horizontal slot preparation (. Fig. 10.16a–l).  

 

 

b

opening; p preparation of the axial wall with the leaned diamond point; q evaluating the presence of the residual carious tissue with an exploratory probe; r removal of the carious tissue with the round bur; s treatment of the tooth structure for the application of the base material; t application of the glass ionomer cement; u, v preparation of the mechanical retentions. w, x evaluating the retentions with an exploratory probe; y, z finishing of the buccal and lingual cavosurface angles; a′, b′ trimming of the gingival cavosurface angle; c′, d′ final aspect of the preparation

351 Tooth Preparations for Amalgam Restorations

c

d

e

f

g

h

i

j

..      Fig. 10.12 (continued)

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k

l

m

n

o

p

q

r

10

..      Fig. 10.12 (continued)

353 Tooth Preparations for Amalgam Restorations

s

t

u

v

w

x

y

z

..      Fig. 10.12 (continued)

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C. R. G. Torres and D. Mehta

a'

b'

c'

d'

10

..      Fig. 10.12 (continued)

a

..      Fig. 10.13  MOD preparation. a Initial aspect; b radiographic aspect of the proximal lesions; c opening of the cavity with a leaned inverted cone diamond point; d, e outline of the occlusal box weakening the marginal ridges; f–h fracture of the marginal ridges with a hand instrument. Obs.: As shown on the picture a and b, on this example, performed on extracted teeth, there is only a pigmented groove on the occlusal surface, without the presence of the caries on the dentin. On a real situation, this groove should not be prepared, and two separated vertical slot preparation could be performed. On this example, the occlusal surface was prepared only for didactic purposes to exemplify a MOD preparation. i–l preparation of the buccal and lingual walls of the

b

mesial box; m–o fracture of the distal marginal ridge; p preparation of the lingual wall of the distal box. q lingual wall of the distal box prepared; r, s buccal wall of the distal box being prepared; t inadvertently grinding of the protective matrix band with the diamond point; u, v evaluating the complete removal of the remaining carious tissue; w, x dentin surface treatment and GIC-based material application. y, z rounding of the axiopulpal angle; a′, b′ preparation of the mechanical retentions in the proximal boxes; c′, d′ finishing of the buccal and lingual cavosurface angles of the proximal boxes; e′, f′ trimming of the gingival cavosurface angles. g′ final aspect of the preparation

355 Tooth Preparations for Amalgam Restorations

c

d

e

f

g

h

i

j

..      Fig. 10.13 (continued)

10

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C. R. G. Torres and D. Mehta

k

l

m

n

o

p

q

r

10

..      Fig. 10.13 (continued)

357 Tooth Preparations for Amalgam Restorations

s

t

u

v

w

x

y

z

..      Fig. 10.13 (continued)

10

358

C. R. G. Torres and D. Mehta

a'

b'

c'

d'

e'

f'

10

g'

..      Fig. 10.13 (continued)

359 Tooth Preparations for Amalgam Restorations

10.5.1  Access Through the Occlusal Surface 10.5.1.1  Outline Form

If there is an occlusal lesion near the marginal ridge, its opening is performed as it has already been described for the Class I preparation, and then the preparation is extended to the proximal area. However, when the lesion is restricted to the proximal surface, it is not necessary to extend the tooth preparation toward the occlusal grooves, because it will unnecessarily weaken the tooth turning it more susceptible to fractures [20]. Therefore, the vertical slot preparation is recommended. On this case, if necessary, the occlusal grooves may receive a pit and fissure sealant to prevent new lesion, but it should never be grinded or cut to receive a restoration. A clinical study reported the effectiveness of sealant and amalgam restoration association [14]. When there is a carious lesion on the occlusal surface far from the marginal ridge, it is treated as a separated Class I lesion (. Fig.  10.12c). However, if there is 0.5  mm or less of the tooth structure remaining in between the occlusal and the proximal preparation, it is better to connect them, avoiding a later fracture of this weakened area. When the preparation to treat the proximal lesion is made separately, the opening to the cavity to access the lesion is performed directly over the marginal ridge. The proximal box is always prepared on the direction of the interproximal contact, despite the tooth position on the arch, i.e., if one tooth is twisted and it is in contact with the adjacent tooth through the buccal surface, the proximal box will be prepared on this region [12]. The proximal surface of the adjacent tooth must be protected from the action of the rotary instrument, to avoid an iatrogenic grinding. For that, an interproximal guard, as shown on . Fig. 6.10a, b should be used, or even small piece of the steel matrix strip assembled on the matrix retainer, positioned on the adjacent tooth. This will avoid the bur or diamond point inadvertently touches the intact proximal surface of the neighboring tooth and causes, in fraction of a second, something that the caries disease would take years to cause [3]. Clinical studies showed that 69% of the adjacent teeth were damaged by the bur during the preparation of the Class II cavities, and the risk of proximal caries on those teeth is almost tripled, due to the bacterial biofilm growing inside the iatrogenic cavitation [21]. It should also be applied a wooden wedge in the interproximal space, to protect the interdental papilla and the rubber dam, as it can be observed on . Figs.  10.12d and 10.13e [22]. It can be noticed that the wooden wedge is placed between the tooth that is being prepared and the matrix strip in the neighbor tooth [22]. If any undesired contact of the rotary instrument with the proximal surface of the adjacent tooth happens, when it is minimal, it will be possible to be corrected the damaged proximal surface with abrasive strips. However, a larger iatrogenic grinding would require a restoration of the contour and smoothness of this surface, filling the cavity created and allowing a correct cleaning of this area by flossing [22].  

 

 

Using a round diamond point, the opening of the cavity until it reaches the lesion is performed. The rotary instrument penetrates toward the cervical region, moving it in the buccolingual direction, following the DEJ, which guides the dentist helping to avoid the contact with the adjacent tooth. It will create a ditch that should be 2/3 on the enamel and 1/3 on the dentin, taking care not to overextend this opening in the buccolingual direction [3, 22]. If it is prepared only on the dentin, the proximal box will be too large [22]. This penetration continues until it reaches the lesion, which depending on its size, will produce a feeling of falling in a hollow space (. Fig. 10.12d–f). Using the long-inverted cone rotary instrument for the small and medium cavities or the cylinder ones for large cavities, the grinding performed to access the lesion is extended toward the marginal ridge, leaving a thin layer of enamel (. Figs. 10.12g–i and 10.13d, e) [3, 13, 22, 23]. The mesiodistal extension of the gingival walls should have the approximate dimension of 0.5–0.6 mm further the DEJ on the dentin, in case mechanical retentions are needed [22], allowing also enough thickness for the restorative material [2, 12]. If there is no more enamel on the gingival cavosurface angle, it may have 0.8  mm of total extension that corresponds to the tip of the No. 245 bur or the No. 1148 diamond point [22]. The lesions are located immediately below the contact point, due to the lack of self-cleaning of this region [12]. The thin layer of enamel still touching the adjacent tooth generally breaks by itself due to the action of the rotary instrument when making it thinner [13, 25]. If this does not happen, the pressure of a hand instrument, such as a dentin spoon, can be applied (. Figs. 10.12j–l and 10.13f–h) [3, 15]. As the caries lesion on the proximal surface generally has an elliptic shape, with its buccolingual dimension greater than the occlusocervical, a pendulum motion is performed to remove the entire carious tissue, without opening too much the preparation in the marginal ridge area (. Figs.  10.12m, n and 10.13i–k). That preserves this functional area, leaving the restoration less exposed to the masticatory loads and consequently to a tooth fracture [6, 16]. This way, the surrounding walls of the proximal box will be convergent toward the occlusal surface, creating the self-retentive preparation, which will also result to thicker restoration margins on the marginal ridge area. The cervical limit of the preparation is located at the end of the lesion, in a way that all margins are placed in healthy enamel. The white spot lesions on this region are removed, because it can appear as a more radiolucent area than the intact tooth in any future radiography, giving the idea of recurrent caries. Because of that, it must be completely eliminated. This does not mean, however, that the entire gingival wall needs to be deepened. This reduction can be performed only on the specific area that corresponds to the lesion. The removal of the contact with the adjacent tooth may simplify the matrix placement and the finishing of the restoration, and it used to be generally recommended as a convenience form. It was also considered as a kind of extension for prevention, due to the fact that the margins are placed on a  

 

 

 

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more easy to clean region [12]. The classic recommendation was that after the end of the preparation, there was a separation of about 0.2–0.3 mm of the adjacent tooth, which corresponds to the tip of a very thin exploratory probe passing through this region [22]. However, considering that the patient must initially have the caries disease controlled and will undergo several preventive measurements, before and after the restorative intervention, the simple reason of extension for prevention becomes unnecessary. According to Almquist et al. [2], for a patient that uses dental floss on the interproximal space, the extension of the proximal walls must be limited necessary for removal of carious tissue and finishing the restoration. An additional extension would only make any sense if the oral hygiene of the patient was restricted to brushing. In some cases, such as on the maxillary premolars and the first molars, the removal of the contact with the adjacent tooth on the buccal wall of the mesial box can expose the margin of the restoration and result in an unnecessary esthetic involvement [3, 11, 20, 22]. In addition, it is possible to make an adequate tooth restoration without removing the contact. Therefore, the removal of the contact should never be done intentionally and is not desired [3, 11, 20, 22]. 10.5.1.2  Resistance Form

On the cases of small- and medium-size lesion, the convergence of the surrounding walls toward the occlusal surface creates thicker margins for the restoration [25]. On the proximal box, the buccal and lingual walls are convergent toward the occlusal surface aiming to remove the entire carious tissue below the contact point with maximum preservation of the marginal ridge, making that food bolus to contact mostly the remaining tooth structure, instead of the restoration. It is known that in a circumferential direction, the long axis of the enamel prisms forms a 90° angle with the tangent that touches the tooth surface on the region of the tip of each prism [12, 22]. Keeping this in mind, it is important that after the tooth preparation, there is no undermined enamel prism on the region of the cavosurface angles. The preparation of the buccal and lingual walls of the proximal box convergent toward the proximal surface or parallel among each other would leave undermined prisms that, with the time, would fracture and result in a marginal ditching (. Fig. 6.38a–f). The preparation of those walls divergent toward the proximal surface solves this problem. The morphology of most posterior teeth, with the buccal surface larger than the lingual one, makes the proximal surfaces converge markedly to the lingual surface. That influences the cavosurface angle of the lingual and buccal walls, in the proximal box of the preparation, and result in thin restoration margins, mostly on the buccal wall (. Fig. 6.38a–f) [25]. This problem is solved by preparing on the buccal wall the Hollenback’s reverse curve or S-shaped curve [2, 12]. It is performed in a way that the buccal wall of the proximal box  

 

..      Fig. 10.14  Direction of the pulpal and gingival walls of the mandibular first premolar

to have a concave contour toward the buccal surface of the tooth. This curve is made only enough to create an amalgam margin at 90° in relation to the external proximal surface. On the lingual side, it is not necessary due to the larger lingual embrasure [12, 22]. Other characteristics that give resistance to the preparation are the pulpal and gingival walls prepared flat and parallel to the occlusal plane. That  allows a more homogeneous stress distribution due to the occlusal loads hiting this area at a 90° angle, besides to avoid the rotation and displacement of the restoration when receiving an eccentric load [12, 22]. One exception happens at the mandibular first premolar, because its lingual cusp is much smaller than the buccal one, making the occlusal plane of this tooth very leaned in the buccolingual direction. To avoid an exposure of the buccal pulp horn, the rotary instrument is placed perpendicular to the occlusal plane of this tooth, which tangents both cusps. That will create a leaned pulpal wall in relation to the long axis of the tooth (. Fig.  10.5c) [25]. However, the gingival wall can be made perpendicular to the long axis of the tooth, up to the cervical limit of the lesion, avoiding an unnecessary invasion of the biological width (. Fig. 10.14, [25]). Due to the use of rotary instruments with flat end and round corners, all the internal line angles of the second set and point angles will consequently be round, improving the stress distribution adaptation of the restorative material. The exception is the axiopulpal external line angle which will be sharp. The buccogingival and linguogingival angles should always be round, because the sharp angles can increase the chances of failures during amalgam condensation and of future secondary caries lesion on this region [9, 16]. The axiopulpal angle must also be rounded to avoid the stress concentration inside the restoration in this area, consequently improving the final resistance [12, 22, 25]. This rounding can be performed with a No. 29 gingival margin trimmer by scraping from the buccal toward the lingual surface and vice versa or with the side of the rotary instrument correctly positioned (. Fig. 10.13y, z).  

 

 

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10.5.1.3  Retention Form

On the occlusal box, when the preparation is performed with the long-inverted cone instrument, it will be self-retentive toward the occlusal surface. When it is done with a cylinder instrument, if the resulting preparation is deeper than wider, it will also be self-retentive. However, if the resulting preparation is wider than deeper, it will be necessary to add retention coves at the base of the cusps, as it has already been described for the Class I preparation (. Fig. 10.8a, b). Toward the proximal direction, the retention is provided by the occlusal contour on the occlusolingual and/or occlusobuccal developmental grooves or by a dovetail lock on the triangular fossae (. Fig. 6.47b). In relation to the proximal box, it will be self-retentive toward the occlusal surface due to the convergence of the buccal and lingual walls. On the proximal ­direction, due to the lack of retention related to divergence of the buccal and lingual walls toward the proximal surface, the retention needs must be analyzed in relation to the occlusal box characteristics, because the amalgam restoration isthmus that connects the occlusal box to the proximal one aids to retain the restorative material in the proximal box [20]. If the occlusal box of the preparation is narrow, with about 1.2 mm or less on the buccolingual direction, the small volume of amalgam may be not enough to prevent the fracture of the restoration at the isthmus region [20]. This may occur due to the masticatory load that hits the marginal ridge of the restoration, which will cause simultaneously tensile and flexural stress at the isthmus region [11]. On this case, the retention locks must be prepared at the buccal and lingual walls of the proximal box (. Fig. 6.47a). Some authors recommend the use of those locks only on the cases that the proximal boxes are wide. However, if the occlusal box of the Class II preparation is wide due to the carious lesion extension or due to previous restorations, the retention locks on the proximal box will rarely be necessary [20]. A study analyzed in vitro the resistance to displacement of amalgam restorations toward the proximal surface when different Class II preparation designs were performed [7]. A vertical slot preparation, without any involvement of the occlusal groove but with retention locks in the buccal and lingual walls, resisted to a displacement load of 18.09 kg. A preparation with the occlusal box in the central groove and the dovetail lock resisted only 7.12 kg. On the other hand, an association of the occlusal box with dovetail locks and proximal box locks resisted to a load of 22.77 kg. They proved that the preparation of locks at the proximal boxes is much more effective than the occlusal box, to retain a restoration on the proximal direction, besides the fact that it preserves the intact tooth structure on the occlusal surface. To prepare the retention locks, the conical No. 1061 diamond point or No. 169 bur is applied on the buccoaxial and linguoaxial line angles, grinding or cutting dentin of the buccal and lingual walls and never on the direction of the pulp, avoiding a pulpal exposure (. Figs. 10.12u, v and 10.13a′, b′) [11, 13, 20, 22, 25]. In case of large and deep carious lesions,  

 

 

 

the locks must be prepared only after the irregular areas have been filled with GIC and the walls have been flattened, avoiding that the recently prepared retentions are covered by the base material. Those locks are prepared with the one-third of the rotary instrument active head near to the tip, grinding more on the region closer to the gingival wall than to the occlusal surface. The grinding is performed mainly with the tip of the head, with the instrument leaning slightly toward the direction of the wall, allowing the penetration at the same depth of the tip diameter, near to the point angle. It is ecomended to reduce the depth toward the occlusal surface and finish at the buccoaxiopulpal or linguoaxiopulpal point angles in case of a preparation that involves the occlusal surface (. Fig. 10.13a′, b′) or before the DEJ on a vertical slot preparations (. Fig.  10.12u, v). This procedure results or retention shaped like a pyramid (. Fig. 6.45b – retention 2) [13]. A refrigeration only with air will improve the visibility, and the reduced speed of handpiece will improve the tactile feeling and the control of the instrument [22]. The end of the retention must be located at 0.2 mm internally from the DEJ, avoiding to produce undermined enamel. The retention efficacy can be evaluated by positioning the tip of the exploratory probe at this region and pulling it toward the proximal surface (. Fig. 10.12w, x). This retention can also be prepared with a gingival margin trimmer, although some dentists prefer to use the small round rotary instruments. The bur is placed on the point angle near to the gingival wall and moved along the buccoaxial and linguolabial, up to the point angle with the pulpal wall [22]. However, the conical rotary instrument is easier to control than a round one [25]. According to Gilmore and Lund [12], this retention reduces the stress at the restoration isthmus, also contributing for its resistance. They make the masticatory loads over the proximal box of the restoration dissipate on the vertical walls of the proximal box, instead of creating high stress inside the amalgam, at the isthmus region. This separates the retention and resistance of the occlusal box from the proximal one [7].  

 

 

 

10.5.1.4  Convenience Form

The axial wall must be slightly expulsive toward the occlusal surface, and it is performed leaning the rotary instrument (. Fig. 10.12p) [15]. This leaning allows a visualization of the gingival wall during the preparation and simplifies the condensation of the restorative material. Therefore, it is a convenience form (. Fig. 6.49a, b). In addition, it increases the material thickness at the region of the limit between the occlusal and proximal box, increasing the resistance of this area. The axial wall is generally flat on the buccolingual direction [15].  

 

10.5.1.5  Removal of the Remaining Carious

Tissue

The remaining carious tissue is removed with a round bur in the low-speed handpiece. The irregularities of the preparation geometrical shape may be corrected by the application of a GIC base (. Figs. 10.12q–t and 10.13u–x).  

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10.5.1.6  Finishing the Enamel Walls

The preparation of the proximal box of a Class II preparation with rotary instruments will, certainly, leave undermined enamel on the buccal and lingual walls near the margins (. Fig. 10.15a–d), which will fracture with the time and produce marginal ditches. A study showed that if not correctly finished, the undermined enamel margins shown microfractures after the application of the matrix bands during the restorative procedure [5]. Therefore, the use of hand instruments is essential. As it was mentioned by Howard [13], to obtain a complete and conservative preparation, which ensures a long-lasting restoration, is much more important than save some few seconds that will be necessary to use the proper hand instruments [13, 20, 22]. The only situation that the correct finishing of the buccal and lingual wall margins of the proximal box can be achieved only with a rotary ­instrument would be on the case of the absence of the adjacent tooth. However, the use of the gingival margin trimmer would still be indispensable at the gingival cavosurface angle. The enamel margin trimming of buccal and lingual walls of the proximal box is performed with a No. 14–15 enamel hatchet, with the bevel facing inside of the preparation [25]. The No. 14 hatchet trims the lingual wall, and the No. 15  

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works on the buccal one (. Figs. 10.12y, z and 10.13c′, d′). At the region of the cavosurface angle of the gingival wall, due to the cervical leaning of the enamel prisms at this area, when the wall is made parallel to occlusal plane, there may remain undermined enamel prisms. They can be removed with the gingival margin trimmers, working from buccal toward the lingual surface and vice versa (. Figs. 10.12a′, b′ and 10.13e′, f′). For the mesial cavity, the No. 28 trimmer is used (10-807-14) (R and L) [22]. The dentist should take care for not making a large bevel but only to trim enough to remove all the short and undermined enamel prisms [13]. The leaning of this trimmed area will be of 15–20° toward the gingiva in relation to the gingival wall surface (. Fig. 6.50) [22]. If there is no enamel at the gingival cavosurface angle, this procedure will not need to be performed.  

 

 

10.5.1.7  Cleaning of the Preparation

It is performed with air-water spray, followed by the application of detergent solutions, which is washed, and the surface dried with an airstream. Then, it is possible to apply 2% sodium fluoride solution for 2 min, followed by drying, or applying 2% chlorhexidine antimicrobial solution, followed by washing and drying, according to what has been previously described for the Class I cavities.

a

b

c

d

..      Fig. 10.15  Finishing of the enamel walls. a Only with the rotary instruments; b–d with the hand cutting instrument (enamel hatchet)

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10.5.1.8  Final Characteristics

of the Preparation Occlusal Box

55 The same as the simple Class I preparation.

Proximal Box 55 Flat, uniform, and smooth walls 55 Gingival wall parallel to the occlusal plane 55 Buccal and lingual walls divergent toward the proximal surface and convergent toward the occlusal surface 55 Axial wall expulsive toward the occlusal surface 55 Internal line angles of the first and second sets, the external line angles and point angles round 55 Round axiopulpal angle 55 Hollenback’s reverse curve on the buccal wall of the proximal box 55 Trimming of the gingival cavosurface angle 55 Mechanical locks on the buccal and lingual walls of the proximal box 10.5.2  Access Through the Buccal or Lingual

Surfaces

The access to a proximal carious lesion on a posterior tooth, through the buccal or lingual surfaces, can be chosen when there are cavitated carious lesions below the contact point, preferably with a small depth in dentin, cervically located, with a remaining tooth structure of at least 2 mm of intact enamel below the marginal ridge [24]. It is especially advantageous when the lesion is located slightly displaced toward the buccal or lingual surfaces, reducing the amount of structure to be grind or cut to access the lesion. This situation is commonly found on lesions at the root and on the proximal surfaces of the patients with the gingival recession due to periodontal problems (. Fig. 10.16a) [17]. This type of lesion is classified as a Class II according to Black but is considered Site 3 according to Mount and Hume. This kind of preparation, named horizontal slot, was developed by Roggenkamp et al. [24] and has advantages of saving time, preservation of the tooth structure, and better esthetic results, besides not changing the occlusal relations and the natural proximal contact [10]. It also shows advantages on rotated teeth. The preparation technique can be observed in . Fig. 10.16a–l.  

 

10.5.2.1  Outline Form

The opening of the cavity is performed with round-shaped No. 1011 diamond point or No. ½ or 1 carbide bur, which is placed below the contact point toward the lesion, at the buccal or lingual surface, according to the proximity to the lesion and the need to hide the presence of the restoration (. Fig.  10.16b). The adjacent tooth must be protected by a metallic matrix band, stabilized by a wooden wedge, inserted on the opposite surface of which the access will be performed.  

The outline is performed with the cylinder-shaped No. 1090A diamond point or No. 56 straight fissure carbide bur. It will enter the preparation until it reaches the limit of the lesion on the opposite surface (. Fig. 10.16c) and moved on the occlusogingival direction, creating this way the axial wall. Placing the rotary instrument on the occlusal limit of the lesion, it is then moved in the mesiodistal direction, creating the occlusal wall (. Fig.  10.16d). The same procedure is repeated to prepare the gingival wall (. Fig. 10.16e). This way, the occlusal and gingival walls will be parallel between each other and perpendicular to the axial wall. The wall opposite to the lesion access will be flat and perpendicular to the other walls.  

 

 

10.5.2.2  Resistance Form

The resistance form is obtained by the preservation of the marginal ridge, which maintains the resistance of the tooth structure. The surrounding walls form a right angle with the external surface of the tooth, allowing an adequate thickness of the restorative material on the restoration margins. 10.5.2.3  Retention Form

Toward the surface where the access to the lesion was performed, the retention is obtained by the fact that the cavity is larger on the buccolingual direction than on the gingivoocclusal direction. On the proximal direction, additional retention grooves must be prepared on the gingivoaxial and occlusoaxial line angles, in a way to avoid the displacement of the restoration. For that, a round No. 1011 diamond point or No. ¼ or ½ carbide bur or even the conical No. 1061 diamond point or No. 169 carbide bur is applied on an oblique position in relation to gingival and occlusal walls, as it can be observed in . Fig. 10.16f, g, on the entire extension of the line angles. It is very important that the grinding or cutting is performed exclusively on the occlusal and gingival walls, but never on the axial wall, due to the complete lack of effectiveness of this grinding on the retention and because of the pulpal exposure possibility. The retention grooves do not have to reach the external surface of the tooth, and it is properly prepared entirely on the dentin.  

>> Additional mechanical retention locks or coves should be never prepared on pulpal or axial walls.

10.5.2.4  Convenience Form

The access to the lesion by the buccal or lingual surface is already a convenience form because it allows preservation of the tooth structure. 10.5.2.5  Removal of the Remaining Carious

Tissue

If there is any remaining carious tissue, it must be removed the way it has already been described for the other types of tooth preparation, with round burs in low-speed handpiece, using the larger diameter compatible to the size of the caries lesion or using dentin spoon excavators.

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10.5.2.6  Finishing the Enamel Walls

It is performed on the gingival, occlusal, lingual, or buccal walls, using the No. 14/15 hatchet (. Fig. 10.16h–j).

apply 2% sodium fluoride for caries prevention, followed only by air drying, according to what has already been described for Class I preparations.

10.5.2.7  Cleaning of the Preparation

10.5.2.8  Final Characteristics

It is performed with an air-water spray followed by a detergent solution, which is washed, and the cavity is dried with an air stream. The disinfection of the preparation walls can be performed with a 2% chlorhexidine antimicrobial solution, followed by washing and drying. Another option is to

55 Access through the buccal or lingual surface 55 Flat, uniform, and smooth surfaces 55 Gingival and occlusal walls parallel between each other and perpendicular to the axial wall

 

of the Preparation

a

b

c

d

e

f

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..      Fig. 10.16  Horizontal slot preparation. a Caries lesion on the CEJ; b access to the lesion with the round diamond point; c penetration with the cylinder diamond point; d preparation of the occlusal wall. e preparation of the gingival wall; f, g preparation of the mechanical

retentions; h–j finishing of the gingival, occlusal and buccal cavosurface angles (the arrows indicate the direction of the movement); k, l final aspect of the preparation

365 Tooth Preparations for Amalgam Restorations

g

h

i

j

k

l

..      Fig. 10.16 (continued)

55 Axial wall parallel to the proximal surface; buccal or lingual wall perpendicular to the other walls 55 Additional retentions on the occlusal and gingival walls 10.6  Class V or Site 3 on Free Smooth

Surface

They are preparations performed on the cervical third of the tooth crown. According to Black, it is considered Class V only the lesions that are located on the free smooth surfaces (buccal and lingual), whereas according to Mount and

Hume, besides those, it is also considered Site 3 the cervical lesions on the mesial and distal surfaces. In the following explanation, it will be included the Site 3 preparations on the buccal or lingual surfaces. Nowadays, the use of amalgam on this type of cavity is restricted to the posterior teeth, when there is no esthetics involvement, especially on molars. They can be shallow lesions on the mechanical point of view, but they are deep on the biological point of view, due to the proximity to the pulpal chamber, and special care should be taken to avoid an accidental pulpal exposure. In . Fig. 10.17a–o, it is shown the preparation of a large lesion on the buccal surface of the second mandibular molar.  

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10.6.1  Outline Form

In general, this kind of lesion is already open due to the collapse of the carious enamel. If the lesion is closed, with only a white or dark spot and intact surface, it is subsurfacial and has to be treated only by preventive measures. The outline is performed with a cone-shaped rotary instrument, such as the No. 1061 or 1063 diamond point or No. 169 carbide bur positioned perpendicular to the surface. The sides of the instru-

ment create the surrounding walls of the preparation, and its tip creates the axial wall [13], maintaining the depth of penetration of the rotary instrument at 0.5 mm further than the DEJ, even if still there is carious tissue further than this region (. Fig.  10.17b, c). This creates a preparation depth of 1–1.25 mm on the gingival cavosurface angle, allowing that the retention grooves may be prepared later without leaving any undermined enamel [22]. On the case of gingival margins on the cement, the penetration can be only 0.75 mm [22]. The  

a

b

c

d

e

f

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..      Fig. 10.17  Class V or site 3 preparation on the buccal surface. a Initial aspect of the caries lesion; b, c beginning of the preparation of the occlusal wall with the conical diamond point; d–f preparation of the mesial and gingival walls. g Preparation of the distal wall; h removal of the remaining carious tissue with the round bur; i, j

treatment of the dentin and flattening of the axial wall with a glass ionomer cement. k, l preparation of mechanical retentions on the axiogingival line angle. m, n preparation of the retentions on the axioocclusal line angle; o aspect of the preparation finished

367 Tooth Preparations for Amalgam Restorations

g

h

i

j

k

l

..      Fig. 10.17 (continued)

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m

n

o

10

..      Fig. 10.17 (continued)

gingival margin generally follows the curvature of the marginal gingiva, because it is a place where the biofilm grows and the lesion border is located. On the large lesion, the mesial and distal margins generally reach the buccomesial and buccodistal or linguomesial and linguodistal axial angles. In general, those preparations take an oval or kidney shaped [12]. However, the dentist must keep in mind that the final dimensions and the shape of the cavity must be a result of the lesion shape and the extension, with maximum preservation of the healthy remaining tooth structure (. Fig. 10.18a–c) [25].  

10.6.2  Resistance Form

On this type of preparation, the restoration will not be submitted to direct masticatory loads but only to the stress distributed inside the tooth structure. However, specific characteristics may favor its durability. During the preparation, the axial wall follows the contour of the external surface of the tooth on the mesiodistal direction, creating a homogeneous thickness of the restorative material and the resistance of the final restoration (. Fig. 10.19a, b) [22, 25]. If the preparation is large on the gingivoocclusal direction, the axial wall can also follow the curvature of the tooth [22]. In narrow cavities, the axial wall is generally flat on the gingivoocclusal direction [13].  

Due to the convex shape of the buccal and lingual surfaces, to the walls to follow the leaning of the prisms, the surrounding walls must be divergent toward the external surface of the tooth, to obtain a 90° cavosurface angle (. Fig. 10.20), which is obtained with the use of cone-shaped rotary instruments with flat tip (. Fig. 10.17c–g) [13, 22]. On the mesiodistal direction, due to the convex shape of the tooth surface near to the axial angles, the mesial and distal walls must be slightly divergent toward the external surface, in a way to follow the direction of the prisms and form a right angle with the external tooth surface [13]. To improve the adaptation of the restorative material and the mechanical behavior of the restoration, the walls must be flat, uniform, and smooth.  

 

10.6.3  Retention Form

Due to the non-retentive shape of the surrounding walls, additional retention must be prepared. For that, retention grooves are prepared along the entire extension of the occlusoaxial and gingivoaxial line angles, on the occlusal and gingival walls. It is done with a short inverted cone point (No. 1031) or carbide bur (No. 33 ½), positioned with its long axis perpendicular to the axial wall, or with a round diamond point (No. 1011) or carbide bur (No. ½), with a depth of

369 Tooth Preparations for Amalgam Restorations

a

b

c

..      Fig. 10.18  a–c Variations on the outline form of the Class V preparation. The outline must be the most conservative as possible, involving only the tooth structure affected by the lesion

a

b

..      Fig. 10.19  a, b Contour of the axial wall in small and large preparation, respectively, in relation to the mesiodistal direction

0.25 mm, which corresponds to half diameter of the rotary instrument head (. Fig. 10.17k–n) [16, 22, 25]. The use of the round rotary instruments is especially recommended on the maxillary molars, once the access adversely affects the correct placement of the inverted cone instrument [16]. To verify the retention quality, the tip of an exploratory probe is placed inside the retention groove and pulled toward the external surface.

10.6.4  Convenience Form

 

In the case of large cavities on the mesiodistal direction, due to the fact that the free smooth surfaces of the tooth are convex, the axial wall of the preparation should also be convex (. Fig. 10.19b) [13]. It is also considered a convenience form because it avoids an accidental pulpal exposure, which could happen in case it was prepared flat [16, 25]. In the case where  

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55 Divergent surrounding walls 55 Additional retention grooves on the occlusoaxial and gingivoaxial line angles Conclusion

..      Fig. 10.20  Direction of the gingival and occlusal walls of the Class V preparations

the cavities are small on the mesiodistal direction, the axial wall is generally flat (. Fig. 10.19a).  

10

10.6.5  Removal of the Remaining Carious

Tissue

On this stage, any remaining carious tissue can be removed with a large round bur at low speed, of a diameter compatible of the preparation size, or with an excavator spoon (. Fig.  10.17h). The undermined or irregular areas of the remaining tooth structure can be filled with GIC and the geometrical shape prepared over the base material (. Fig. 10.17i, j). If a base is necessary, the retention grooves must be prepared after its placement, in a way to avoid its closing during the base material application.  

 

10.6.6  Finishing the Enamel Walls

Due to the expulsive shape of the surrounding walls, no undermined enamel prisms will be left after the use of the rotary instrument. 10.6.7  Cleaning of the Preparation

It is performed in the same way as described for other preparations. 10.6.8  Final Characteristics

of the Preparation

55 Flat, uniform, and smooth walls 55 Round line angles of the first set 55 Sharp line angle of the second set 55 Convex axial wall following the contour of the buccal or lingual surface on large preparation or flat axial wall on small preparation

This chapter described the principles associated with the preparation of posterior teeth to receive amalgam restorations. The preparation procedure for Class I, II, and V cavities was presented, including all characteristics on each case to get retention and strength for the restoration. Due to its nonadhesive characteristics, the details shown are extremely important for the durability of the restoration, and must be kept in mind when this kind of procedure is performed by the clinician. Although the use of amalgam is being extremely reduced in recent years, it is still an excellent alternative in cases where the control of moisture is difficult or the access to modern material is restricted due to economic reasons.

References 1. Alexander WE, Mc Donald RE, Stookey GK. Effect of stannous fluoride on recurrent caries—results after 24 months. J Dent Res. 1973;52:1147. https://doi.org/10.1177/00220345730520052401. 2. Almquist TC, Cowan RD, Lambert RL. Conservative amalgam restorations. J Prosthet Dent. 1973;29:524–8. 3. Baratieri LN.  Dentística. Procedimentos preventivos e restauradores. 2nd ed. Sao Paulo: Santos; 1993. 4. Baratieri LN, Monteiro Junior S, Andrada MA, Ritter AV. Odontologia Restauradora: Fundamentos e Possibilidades. Santos: São Paulo; 2001. 5. Boyde A, Knight PJ. Scanning electron microscope studies of class II cavity margins. Matrix band application. Br Dent J. 1972;133:331–7. 6. Bronner FJ. Engineering principles applied to class II cavities. J Dent Res. 1930;10:115–9. 7. Crockett WD, Shepard FE, Moon PC, Creal AF. The influence of proximal retention grooves on the retention and resistance of class II preparations for amalgams. J Am Dent Assoc. 1975;91:1053–6. 8. Dérand T.  Marginal failure of amalgam class II restoration. J Dent Res. 1977;56:481–5. https://doi.org/10.1177/002203457705600506 01. 9. Elderton RJ.  The prevalence of failure of restorations: a literature review. J Dent Elsevier. 1976;4:207–10. https://doi. org/10.1016/0300-5712(76)90049-X. 10. Ewoldsen N.  Facial slot class II restorations: a conservative technique revisited. Can Dent Assoc. 2003;69:25–8. 11. Fichmann DM, Santos W.  Restaurações à amálgama. Savier: São Paulo; 1982. 12. Gilmore HW, Lund MR.  Operative dentistry. Saint Louis: Mosby; 1973. 13. Howard WW. Atlas of operative dentistry. 2nd ed. St. Louis: Mosby; 1973. 14. Mertz-Fairhurst EJ, Curtis JW, Ergle JW, Rueggeberg FA, Adair SM. Ultraconservative and cariostatic sealed restorations: results at year 10. J Am Dent Assoc Elsevier. 1998;129:55–66. https://doi. org/10.14219/JADA.ARCHIVE.1998.0022. 15. Mondelli J, Franco EB, Pereira JC, Ishikiriama A, Francischone CE, Mondelli RL, et al. Dentística: Procedimentos Pré – Clínicos. Santos: São Paulo; 2002. 16. Mondelli J, Ishikiriama A, Galan JJ, Navarro MF.  Dentística Operatória. Sarvier: São Paulo; 1976. 17. Mooney B. Operatoria dental. Panamericana: Buenos Aires; 1995. 18. Mount GJ, Hume WR. A revised classification of carious lesions by site and size. Quintessence Int (Berl). 1997;28:301–3.

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19. Neto NG, Carvalho RC, Russo EM, Sobral MA, Luz MA. Dentística Restauradora: Restaurações diretas. Santos: São Paulo; 2003. 20. Osborne JW, Summitt JB.  Extension for prevention: is it relevant today? Am J Dent. 1998;11:189–96. 21. Qvist V, Johannessen L, Bruun M. Progression of approximal caries in relation to iatrogenic preparation damage. J Dent Res. 1992;71:1370–3. https://doi.org/10.1177/00220345920710070401. 22. Roberson TM, Heymann H, Swift EJ. Sturdevant’s art and science of operative dentistry. Orlando: Mosby/Elsevier; 2006. 23. Rodda JC. Modern class 2 amalgam cavity preparations. N Z Dent J. 1972;68:132–8.

24. Roggenkamp CL, Cochran MA, Lund MR. The facial slot preparation: a nonocclusal option for class 2 carious lesions. Oper Dent. 1982;7:102–6. 25. Simon WJ.  Clinical operative dentistry. Philadelphia: Saunders; 1956. 26. Stratis S, Bryant RW. The influence of modified cavity design and finishing techniques on the clinical performance of amalgam restorations: a 2-year clinical study. J Oral Rehabil. 1998;25:269–78. https://doi.org/10.1046/j.1365-2842.1998.00227.x. 27. Vale W. Cavity preparation. Iri Dent VRev. 1956;2:33–41.

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Amalgam Restorations Carlos Rocha Gomes Torres, Shankargouda Patil, and Graziela Ribeiro Batista 11.1

Introduction – 374

11.2

Instruments and Materials – 377

11.3

Restorative Technique – 378

11.3.1 11.3.2 11.3.3 11.3.4

 lass II Restorations (Site 2) – 378 C Restoration of Compound Class I Preparations – 394 Restoration of Class V Preparations (Site 3) – 397 Restoration of Horizontal Slot Preparations – 397

11.4

Finishing and Polishing – 402

11.5

Durability of Amalgam Restorations – 405

11.6

Controversy About the Use of Amalgam – 407 References – 409

© Springer Nature Switzerland AG 2020 C. R. G. Torres (ed.), Modern Operative Dentistry, Textbooks in Contemporary Dentistry, https://doi.org/10.1007/978-3-030-31772-0_11

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Learning Objectives The learning objectives of this chapter are related to the following topics: 55 Instruments and materials necessary to perform the restoration 55 Restorative technique for Class I (simple and compound), II, and V preparations 55 Application of the matrix and wedge for Class II and V restorations 55 Trituration and condensation 55 Pre-carve burnishing procedure 55 Carving of occlusal and smooth surfaces 55 Post-carve burnishing procedure 55 Occlusal adjustment or a new restoration 55 Finishing and polishing of amalgam restoration 55 Durability of amalgam restorations 55 Controversy about the use of the amalgam

11.1  Introduction

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Amalgam means any material that contains mercury as the main ingredient on its composition. A specific combination based on the mixture of silver-tin alloy with mercury is called dental amalgam. It is condensed into a tooth preparation, becoming solid after crystallization [16]. It is one of the oldest restorative materials that is still in use. An old Chinese medical text written by Su Gon in 659 a.d. describes the use of a silver paste to restore teeth. Another text, from 1505, describes the composition of such silver paste, which should be prepared with 10 parts of mercury, 4.5 parts of silver, and 9 parts of zinc. Around 1833, this material was brought from Europe to the United States, causing being rejected from most dentists of that time which considered that only the cohesive gold foil should be used for tooth restorations. That began the socalled amalgam war, and the American Society of Dental Surgeons (ASDS) declared that the use of amalgam should be considered malpractice, trying to oblige all members to never use this material and sign a pledge to abstain from its use. This attitude leads to the premature disbanding of ASDS because most of its affiliated members decided to leave the society [15]. The composition of amalgam alloy was studied by the famous professor Greene Vardiman Black, in 1895, who improved its physical properties and created its standardization, which increased its acceptance by the practitioners.

Amalgam means any material that contains mercury as the main ingredient on its composition. A specific combination based on the mixture of silver-tin alloy with mercury is called dental amalgam.

According to Markley, amalgam has saved and continues to save more teeth than all the other restorative materials combined [12]. Several factors contributed and continue to con-

..      Fig. 11.1  Restoration removed showing oxides deposited on the walls, which promote the sealing of the interface

tribute for this material’s huge clinical success. Among them are the low cost in relation to the indirect restorations and the direct composite and its simple technique of use. It is also less sensible to some variations of the restorative procedure. It presents a high resistance to masticatory loads and wear. After the polishing, its superficial roughness is satisfactory, which results in a smaller bacterial adhesion in relation to the other direct restorative material. It also presents the capacity of self-sealing the tooth/amalgam interface, by deposition of corrosion products, which progressively reduces the marginal microleakage with time, preventing the occurrence of caries lesions in the interface and decreasing the postoperative sensitivity [6]. The corrosion products deposited on the interface are tin oxide, tin oxychloride, and some copper oxides, as can be observed in . Fig. 11.1 [9]. All those factors allow an excellent clinical durability for those restorations, which can reach 20 years or more. However, one of the most important deficiencies of the silver amalgam is its metallic color, creating unesthetic restorations with artificial appearance. This has resulted in the decrease of amalgam use, especially on more economically developed countries. Despite the efforts of the researchers to develop an esthetic material that could replace amalgam, a large number of restorations are still made using this material worldwide [14]. However, on the economically deprived countries, the access to dental treatment has increased, and amalgam is still used for the treatment of teeth affected by caries lesion. This made the amount of dental amalgam sold on the entire world still big, despite the fact that the preference for its use is decreasing. Nowadays, the dental amalgam is indicated only for restorations on the posterior teeth, where the esthetics is not a main concern, such as on medium- to large-sized Class I and II preparations and large Class V preparation. Its choice as a restorative material is based on the size of the area to be restored; on the materials used on the nearby areas, such as  

375 Amalgam Restorations

on the adjacent and antagonist teeth; economical factors; and whether it will produce an acceptable esthetic result [10]. The physical properties of the crystallized amalgam have a great influence on its clinical applications. The compressive strength of the enamel is about 400 MPa, while for the amalgam, it is around 340–510 MPa. However, its tensile strength is only 48–70 MPa, which produces a good resistance to compressive loads during mastication but predisposes to fracture when strong tensile forces are predominant [16]. Therefore, its ideal indication is intracoronal tooth ­preparation, where it will mostly undergo compressive loads. When comparing the characteristics between the amalgam and composite resin, some factors can be considered. The amalgam has a coefficient of thermal expansion 2.5 times bigger than the tooth structure, but smaller than composite which is 3–6 times greater than the tooth. That makes the restoration to suffer higher volumetric changes than the tooth structure during thermal variations in the oral cavity. In addition, it is more wear resistant than the composite and, therefore, is indicated on restorations of teeth with heavy occlusal load or when all the occlusal contacts of the teeth must be restored, situations which are challenging to the composites [16]. It is also indicated on the cases where the lesions reach the root surface, with absence of enamel on gingival margin, due to the poor adhesion of composites to the dentin/cementum margin and formation of marginal gaps [16]. It is also the best material on the areas of hard isolation of the operating field, because of the higher risk of preparation contamination with water, saliva or blood. Even though contamination is never desired, it is less damaging for amalgam restorations than for composite. However, due to its adhesive properties, composites allow more conservative tooth preparations than amalgam and are the first choice on very small carious lesions [16]. Therefore, amalgam is mainly indicated for large cavities on severely destroyed posterior teeth [9]. Other advantage of amalgam over direct composite restoration is that the first is condensed into the cavity instead of just adapted into it. The condensation pressure toward the gingival wall helps to assure that no internal empty spaces remain along the margins. The condensation toward the proximal direction aids to assure to obtain the proximal contact and the adequate contour. When using composite resin, the application does not move the band toward the contact. The proximal contact and the contour are obtained mainly due to the correct use of matrix and wedge system [16]. The dental amalgam alloy may vary according to its composition. Although the basic components are silver, tin, copper, and zinc, the amount of each ingredient varies between the commercial brands. Conventional alloys have 65–70% silver, 25–30% tin, 0–6% copper, and 0–2% zinc [9]. Silver is the main component, while tin is more soluble in mercury and provides a better crystallization reaction, also improving the characteristics for handling and adaptation in the preparation. The first dental amalgams used to contain less than 5% of copper and showed limited corrosion resistance. In 1965, the first high-copper amalgam alloy was available in

..      Fig. 11.2  Dental amalgam crystallization reactions

market, which was proved to be much more resistant to corrosion. Amalgam alloys are considered high-copper-content ones when they have 10–30% of this metal [9]. The higher copper level of these alloys reduces the formation of λ2 phase, produced by the reaction between tin and mercury, since tin reacts with copper forming the ε and η1 phases (copper-tin) [9]. Those alloys are preferred in relation to the low-copper content ones because they produce more resistance and durable restorations. On . Fig. 11.2, it is shown the setting reactions of silver amalgam, according to its composition. After the mixture, mercury begins to dissolve and react with the external layer of silver-tin particles. About 15% of these particles are consumed to produce a complete reaction with mercury to yield a matrix of solid materials derived from the reaction. The particles of the alloy that do not react remain mixed inside the matrix to contribute to the mechanical strength. Initially, the material shrinks due to particle dissolution. However, with the crystals growing, an expansion finally happens and compensates the initial shrinkage. The amount of copper on the alloy influenced the amalgam creep, which is the plastic deformation of the material after its setting when receiving a constant low-level load, such as the occlusal contact over the restoration. When deforming, the amalgam is projected beyond the margins, resulting in marginal degradation.  The larger the copper level in the alloy, the lower the creep will be. There are two types of high-copper-content alloys. The first is a mixture of low-copper-content lathe-cut particle with high-copper-content spherical particles. On this case, the reaction occurs in two stages. On the first stage, the formation of λ2 phase (mercury-tin) happens, but it is quickly converted into ε and η1 phases (copper-tin) on the second stage. The second type of alloy is a single composition with all particles having high copper content. On this case, there is no formation of λ2 phase (. Fig. 11.2).  

 

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The compressive strength of λ phase (silver-tin) is 4923 kg/cm2, while that of λ1 (silver-mercury) phase is 1758 kg/ cm2 [5]. On the other hand, the compressive strength of λ2 phase is of only 703 kg/cm2, and this way it is the most fragile phase of the crystallized amalgam. It forms a continuous web inside the material. This way, once the corrosion begins, it continues through the whole restoration [9]. On the conventional amalgam, there is selective corrosion on λ2 phase, while on the high-copper-content amalgam, there is a selective corrosion on ε and η1 phases [9]. On the other hand, ε and η1 crystals do not communicate with λ2 crystals, reducing the corrosion, which will happen only on the surface. Therefore, the presence of λ2 phase must be avoided at all costs, and it is recommended the use of high-copper-content alloys. They show a higher corrosion resistance and compressive strength, a smaller marginal degradation, and a higher surface gloss after polishing in relation to the conventional ones [9]. Both low- and high-copper-content alloys produce corrosion products such as tin oxide (solid) and tin oxychloride (soluble) crystals. The solid corrosion products help to seal the interface tooth restoration. Zinc has been added to the alloys to act as a scavenger of foreign substances, such as copper and tin oxides, during the manufacturing process [9]. However, when in contact with water during the condensation into the cavity, the formation of ZnO and hydrogen gas (H2) occurs, which may result in the delayed expansion of the material and cause the fracture of the remaining tooth structure [12]. Clinically, it can be observed that the material extrudes from the cavity, as can be seen in . Fig. 11.3. It is considered acceptable a dimensional change of approximately 20 μm/cm for the material after the crystallization. However, on the case where the material comes in contact with water, values up to 400 μm/cm are observed after 8 h [6, 9]. On those cases, it is common for the patient to report a delayed dental sensitivity, 5–7 days after receiving the restoration, due to the stress caused by the restorative material on the preparation walls [12]. The contact with water can also produce porosity on the surface [12]. For this reason, some alloys have no zinc on its composition.  

However, the zinc-free alloys present an inferior clinical performance than zinc-containing ones, because it increases the corrosion resistance in the oral cavity and reduces the marginal failures [9]. This occurs due to the corrosion of the Zn instead of the Cu-Sn phase [9]. The oxide scavenger properties of Zn keep the amalgam with a light color during the manufacturing process and throughout the clinical life of the restoration [6]. The zinc-free alloys used to be indicated on pediatric dentistry, when the control of the moisture was harder, mainly on deciduous teeth. According to the method of production of amalgam alloy particles, they may have different morphologies. The most common type is called lathe-cut particles (. Fig. 11.4a). They are irregular particles obtained by melting the metals to make an ingot, which is ground to produce “shavings” of metal that are milled to reach the recommended particle sizes, which is verified by passing it through sieves [6]. Then, the particles receive a thermal treatment to release the internal stress induced by the grinding process. They can be classified according to the particle size in regular cut, with larger particles, and fine cut, with smaller particles. The use of fine-cut particles allows a better adaptation on the cavity angles than the regular-cut ones and also a better surface smoothness after polishing [6]. They also mix faster with mercury and are better handled by the dentist, have a more uniform setting reaction, and produce a higher initial strength for the restoration [6]. The lathe-cut particles have the advantage that, during the condensation procedure, the particles come close and interlock, maintaining its position. During this procedure, the total volume of the material is reduced by the elimination of the empty spaces and the excess of mercury. Therefore, it can be considered that amalgam really becomes more dense. The average particle size of modern alloys is up to 20–25 μm. Other distinct types of amalgam alloy particle are obtained through atomizing the melted alloy, spraying through a jet nozzle under high pressure, inside a cold atmosphere containing nitrogen gas, which protect the particles from oxidation during the cooling period [9]. This procedure results in the formation of small spheres (. Fig. 11.4b). Then, they are treated with acid and undergo a thermal treatment. The spherical alloys have the advantage to form amalgams that better adapt to the irregularities of the preparation, need smaller condensation pressure, and are easier to carve, producing a better superficial smoothness of the restoration [9, 16]. In addition, they need 10% less mercury for amalgamation [14]. However, this material cannot be condensed with small instruments, because the particles “slide” on each other. The smaller condensation force applied makes more difficult to obtain an adequate contact point with the neighbor tooth [9]. To associate the positive properties of both types of particles, the admixed alloy was developed with both lathe-cut and spherical particles (. Fig.  11.4c) [19]. Also called dispersed phase alloy, it generally has 2/3 of spherical and 1/3 of lathe-cut particles. Adjusting the ratio of the two particles, the manufacturers were able to obtain the ideal material in  

 

 

..      Fig. 11.3  Delayed amalgam expansion due to moisture contamination at the moment of the amalgam insertion

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a

b

c

..      Fig. 11.4  Types of amalgam alloys. a Lathe cut; b spherical; c admixed

..      Fig. 11.5  Organization of the clinical instruments for amalgam restorative procedure

terms of physical properties and handling characteristics [9]. This material offers easy condensability, adequate adaptation into the cavity irregularities, and good surface smoothness. The selection of the alloy to be used must be performed considering the setting time, consistency, carvability, and surface smoothness, inside the limits of the acceptable physical properties [6]. 11.2  Instruments and Materials

To perform the restorative procedure using dental amalgam, the instruments and materials necessary are described below. A suggestion for organization of the instruments on a logical sequence of use can be observed in . Fig. 11.5. 55 Amalgam alloy and mercury, preferably pre-­ proportioned capsules 55 Dental tweezer  

55 Flat first surface clinical mirror 55 Double exploratory probe 55 Iris straight scissor 55 Rubber dam frame 55 Ainsworth or Ivory puncher 55 Palmer clamp holder forceps 55 Rubber sheet 55 Clamps No. 200, 202, 205, 207, 209, and 14 A 55 Dental floss 55 Number 1 plastic filling instrument 55 Amalgam carrier 55 Amalgam well or a rubber dappen dish 55 Tofflemire matrix retainer 55 Matrix bands of two widths (5 and 7 mm) 55 Dentin excavator spoon (No. 17 and No. 19) 55 Alcohol lamp 55 Low fusing compound 55 Anatomic wooden wedge of several sizes

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55 Curved Halstead mosquito forceps 55 Ward amalgam condensers (No. 00, No. 1, No. 2, and No. 3) 55 Hollenback carvers (No. 3 and No. 3S) 55 Frahm carvers (No. 2, No.6, and No. 10) 55 Shoshan-A carver 55 Discoid-cleoid carver 55 Interproximal carver (IPC I) 55 Egg-shaped burnisher (No. 29) 55 Bennett burnisher (No. 33) 55 Hollenback burnisher (No. 6) 55 Miller articulating paper forceps 55 Thin double-color articulating paper (black and red) 11.3  Restorative Technique

11

When the tooth preparation is finished, the operating field must be properly isolated, avoiding amalgam contamination by moisture from saliva or crevicular fluid, which could result in a delayed expansion, surface corrosion and tarnish increasing, strength reduction, and premature failure of the restoration. Preferably, rubber dam isolation should be made, even though a well-performed and monitored cotton roll isolation on a patient with a low salivary flow can also be acceptable. After that, the preparation cleaning is performed. On shallow and medium-depth preparation, an anionic detergent is applied, followed by washing with air/water spray and drying with airstream. Then, a neutral 2% sodium fluoride solution is applied for 2–4 min and dried with an airstream. Another option is to rub for 30s onto the preparation walls a dentin desensitizer, containing 5% glutaraldehyde and 35% hydroxyethyl methacrylate (HEMA), which reduces the dentin permeability by protein precipitation inside the tubules [16]. After that a gentle drying is performed, without desiccating the dentin. On deep and very deep preparations, the need of a pulpal protection must be evaluated, with the application of a liner material, as described in 7 Chap. 9. A base can be placed on the pulpal wall, to create a flat surface, or on the surrounding walls to fill the undermined enamel areas, creating the artificial dentin. The amalgam has a high thermal conductivity. Therefore, it should not be placed near the dental pulp without a liner or a base [16]. It is important that the liner or base material does not reach the cavosurface angle, which must be in contact with amalgam.  

>> Amalgam has a high thermal conductivity and should not be placed in direct contact with pulpal wall of deep preparations without a liner or a base.

11.3.1  Class II Restorations (Site 2)

The following sentences describe the entire restorative technique for a Class II preparation, involving the proximal surface (. Fig.  11.6a–m′). Except the matrix and wedge  

application steps, the restorative technique for Class I preparations is exactly the same. Therefore, it will not be described separately. 11.3.1.1  Application of the Matrix and Wedge

For amalgam to reach the required and physical properties produce a long-lasting restoration, it needs to be strongly condensed on a space with rigid walls [12]. In case of Class II preparations, a matrix and wedge system must be used, according to what has been detailed in 7 Chap. 8. The type most commonly used is the universal matrix, using a matrix retainer. In case the tooth to be restored is the anchor tooth, which will receive the retention clamp for the rubbed dam isolation, a custom-made riveted, welded, or T matrix can be chosen since the clamp interferes on the correct placement of the matrix retainer [6, 13]. The same is valid when the proximal boxes are very large on the buccolingual direction or one or more cusps were lost, which impair the proper contour of the universal matrix. First of all, a matrix band must be selected. The straight or boomerang-shaped strip can be used. One of the two occluso-­gingival widths (5 or 7 mm) is chosen. The correct width is selected according to the occluso-gingival dimensions of the tooth to be restored. To the gingival direction, the strip width must be enough to surpass more or less 1 mm of the gingival cavosurface angle of the preparation. To the occlusal direction, the edge of the band must go 1 mm further than the marginal ridge of the adjacent tooth, allowing the correct reconstruction of the proximal surface [9, 10, 12, 16]. About 7 cm of strip is used for the premolars and molars. The thickness of the matrix band varies from 0.03 to 0.05  mm [6, 9]. The thicker and thinner ones both have inconvenients. The thinner ones are hard to pass through the proximal contact area due to insufficient stiffness, besides the fact that they can easily be deformed during amalgam condensation, increasing the risks of overhangs on the margins. The thicker ones remain more stable during the condensation, but a proper wedging and burnishing of the matrix are essential, to create an adequate proximal contact. After that, the matrix band can be assembled on the retainer. If the Tofflemire type is selected, the model with guide posts at a 90° angle is placed on the buccal side of the tooth, while the model with the guide posts contra-angled is placed on the lingual side, indicated when the preparation extends to the buccal surface (. Fig. 8.15a) [6, 16, 20]. The matrix retainer is placed with the slotted side of the head directed gingivally to allow easy separation of the retainer from the band occlusally [9, 16]. In general, the long axis of the instrument is placed on the mesiodistal direction [6]. The buccal or lingual placement is a matter of convenience and amount of remaining tooth structure. However, on the mandible, the lingual placement is, sometimes, more adequate due to the leaning of the buccal surface toward the lingual side, providing better stability to the retainer [9].  

 

379 Amalgam Restorations

Tip

The buccal or lingual placement of the retainer is a matter of convenience and amount of remaining tooth structure. However, on the mandible, the lingual placement is sometimes more adequate due to the leaning of buccal surface toward the lingual side, providing better stability.

Then, the contour of the matrix band can be modified to adapt the convex contour of the proximal surface of the posterior teeth. For that, it is analyzed which part of the matrix will be responsible for the restoration of the proximal contour and the contact point. Without removing the matrix from the retainer, this section is placed over a paper mixing pad and burnished with a No. 29 egg-shaped amalgam burnisher [10, 16]. It is rubbed perpendicularly to the long axis of the strip,

as can be observed in . Fig. 11.6b. It can also be used for this purpose a No. 144 contouring plier. Care must be taken to establish the contour in harmony with the tooth to be restored, with a particular curvature for that contact area [10]. Then, the set is taken in position and the matrix is tightened. Care on the assembling and the application of the matrix is more important than tightening it. Tightening the matrix strongly around the tooth does not necessarily mean that it will prevent overhangs or produce the desired contour [10]. Instead, this may result in an inadequate contour [6]. At this moment, the selected matrix must be checked if it has the adequate width, that is, if its margin is cervical to the gingival cavosurface angle and above the marginal ridge of the adjacent tooth. The next step is the application of the wooden wedges in the interproximal space, in a way to avoid the overflow of amalgam to the cervical region, create a slight tooth displacement, and compensate the thickness of the matrix band  

a

b

c

d

..      Fig. 11.6  MOD amalgam restoration. a Tooth preparation; b burnishing of the matrix at the region of contact over the paper mixing pad; c traction of the rubber sheet; d wedge application; e Test of wedge retention; f checking the gingival margin matrix adaptation; g burnishing of the matrix; h checking the positioned matrix and wedge system; i application of amalgam; j, k condensation toward the internal angles of the proximal box; l filled proximal boxes; m, n Filling and condensation on the rest of the preparation; o condensations toward the buccal restoration margin; p condensation toward the lingual restoration margin; q pre-carve burnishing; r carving of the occlusal embrasure in the marginal ridge; s carving of the cusps incline; t

removal of the matrix retainer; u, v Removal of the matrix band; w adjustments of the height of the marginal ridge; x removal of the cervical excess; y, z, a′, b′ use of the No. 3S Hollenback, cleoid, discoid, and No. 2 Frahm carvers, respectively; c′, d′ Use of No. 6 and 10 Frahm carver; e′ superficial smoothing with a small cotton ball; f′ visualization of the proximal contour and the contact point; g′, j′ post-carve burnishing with the exploratory probe and No. 6, No. 33, and No. 29 burnishers, respectively; k′ Passing the dental floss through the contact point touching the adjacent tooth; l′ smoothing the cervical region with the dental floss; m′ final aspect of the burnished restoration

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g

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k

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..      Fig. 11.6 (continued)

381 Amalgam Restorations

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n

o

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r

s

t

..      Fig. 11.6 (continued)

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u

v

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x

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a’

b’

11

..      Fig. 11.6 (continued)

383 Amalgam Restorations

c’

d’

e’

f’

g’

h’

i’

j’

..      Fig. 11.6 (continued)

11

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C. R. G. Torres et al.

k'

l'

m'

11 ..      Fig. 11.6 (continued)

[6, 12, 20]. They are applied through the larger embrasures that in general are the lingual ones. There is an exception between the first and the second maxillary molars, due to the larger dimension of the lingual surface of the maxillary first molar. However, on the cases of teeth that are rotated or badly positioned somehow, the situation must be analyzed to check which really the larger embrasure is. The wedges are inserted with a curved mosquito-type forceps or with specific forceps for this purpose to allow a better grasp [12]. Sometimes the rubber dam tends to loosen the wedge, due to the fact that wedge application results in the stretching of the rubber, which tends to go back to its original position, and this pulls the wedge out of the interproximal space. To avoid this situation, the rubber septum is stretched before and during the application of the wedge, on the opposite direction (. Fig. 11.6c, d) [16]. The wedge size is chosen according to the size of the interproximal space. It is very important to apply it between the teeth with some pressure; otherwise, it will not work properly. When there is a MOD preparation to be restored, the wedges are placed simultaneously on the mesial and distal surfaces of the tooth. Amalgam overhangs may happen as a result of the wedges loosening before the condensation. To avoid this problem, it is important to check if they are firmly settled in the interproximal space, trying to pull it with a slight force using the tip of an exploratory probe (. Fig.  11.6e). A slightly force should not cause its displacement [16].  

 

After that, the adaptation of the matrix on the cervical region is checked with the tip of an exploratory probe, which is pressed toward the cavosurface gingival angle (. Fig. 11.6f) [16]. The dentist must press and drag the probe’s tip along the margins, on both direction, which also contributes to displace any weakened and undermined enamel left. An airstream is then applied to clean all the fragments [16]. If the probe penetrates between the matrix and the cavosurface angle, that indicates the possibility of amalgam overflow during the condensation. On this case, the wedge must be removed and replaced by another with larger dimensions, repeating the checking process. The width of the wedge base must be slightly larger than the space between the tooth to be restored and the adjacent one, to separate them [9]. It must touch the external surface of the tooth cervically in relation to the gingival wall of the preparation [9]. To guarantee the correct restoration of the proximal contact, an additional burnishing of the matrix band toward the adjacent tooth is performed using the back of a dentin spoon or a No. 6 Hollenback’s burnisher (. Fig.  11.6g) [16]. It is moved on the buccolingual direction. Then, the matrix is checked to see if it is properly touching the adjacent tooth, when observing it from the buccal or lingual direction, with the aid of a clinical mirror (. Fig. 11.6) [16]. If there is still no contact, the matrix retainer can be loosened slightly and the matrix burnished once again. If the contact is still not established, then a custom-made matrix should be prepared [16].  

 

 

385 Amalgam Restorations

11.3.1.2  Trituration and Condensation

When the operating field is isolated, the cavity is cleaned, and the matrix and wedge system is in position, the trituration or mixing of the amalgam can start to fill the preparation. The aim of trituration is to remove the thin layer of oxide that covers the particles and make them come in perfect contact with mercury, allowing an adequate and homogeneous setting reaction [6]. On the market amalgam alloy powder or tablets and mercury can be found in bulk on separated bottles or in pre-proportioned capsules (. Fig. 11.7a, b). The trituration of alloy in bulk can be performed manualy or through a mechanical device. For the manual trituration, the alloy:mercury ratio  must be defined  by weight, through a Crandall’s scale, and the mixture performed with a ground glass mortar and pestle. Depending on the alloy type, this ratio may vary. In general, a 1:1 ratio is used. However, the alloys with spherical particles may use a 4:5 ratio, resulting in 42–44.5% of mercury. However, the correct ratio will depend on the material to be used, and the manufacturer’s instructions must be followed. The amount of mercury required is the one enough to cover the individual particles of the alloy [6]. The lesser mercury used, the faster the setting of the material will be [6]. In general, the smaller the size and the more uniform the shape of the particles are, the lesser the necessary amount of mercury will be. The spherical particles have a smaller surface area in relation to weight, and that is why they require less mercury to be wetted [14]. On . Fig.  11.8a–o, it is presented the sequence for Crandall’s scale use and the hand trituration. First, the desired amount of mercury is placed on the scale according to the size of the preparation, which will cause the scale to lean to one of the sides (. Fig. 11.8a–c). The weights are moved until it is once again on the horizontal position (. Fig.  11.8d). Then, mercury is transferred to the mortar, which will cause the scale to lean to the other side (. Fig.  11.8e, f). If a 1:1  

 

 

 

 

a

11

ratio  is used, the scale is already set. If necessary, a cross-­ multiplication can be used to find the correct amount of alloy will reach the manufacturer’s recommended ratio for that amount of mercury. The scale is adjusted, and the alloy particles are placed on the scale until it is once again on the horizontal position (. Fig.  11.8g, h). Then, it is transferred into the mortar (. Fig. 11.8i). The pestle must be held on a palm-and-thumb grasp and moved on a circular motion, with a load of 1–2 kg, at 150–180 rpm (. Fig. 11.8j) [8]. When the mixture is correct, the amalgam begins to unstick of the mortar walls (. Fig. 11.8k). This process takes about 1–2 min. Then, the excess mercury that is present on the material can be removed by squeezing it on a sheet of chamois leather and twisting it with a tweezer (. Fig. 11.8l–n) [6]. The content is moved into a rubber dappen dish to homogenize the material, which is ready to be transferred into the cavity (. Fig. 11.8o). Hand trituration is no longer used nowadays. Mechanical trituration of the alloy particles and mercury may be performed with a device called amalgamator, as the ones shown in . Fig. 11.9a, b. They have a compartment for alloy and another one for mercury. There is the possibility to adjust the ratio of each component and the time of the mixture. The mechanical trituration of the precapsulated amalgam is also very simple (. Fig. 11.9c, d). The devices for this purpose have a holder, where this capsule is connected, and the only adjustment needed is the time for mixing the amalgam. These amalgam capsules have the exact amount of mercury, and they do not require to be squeezed through the chamois leather [16]. The amalgamator should have a mixing speed above 3800 rpm [14]. The material is then transferred to an amalgam well and is ready to be placed into the preparation. The correct trituration of the amalgam is very important for the final quality of the restoration. When performed properly, according to the manufacturer’s recommendations, the amalgam must be shiny and plastic. When a small  

 

 

 

 

 

b

..      Fig. 11.7  a Mercury and amalgam alloy in bulk; b pre-­proportioned capsules

 

 

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amount of a recently triturated amalgam is dropped onto a hard surface, from 25 to 30 cm high, it will slightly flatten but remains cohesive [9, 16]. The under- or overtrituration of the material may seriously compromise the physical characteristics of the crystallized amalgam. When it is undertriturated, the material looks crumbly or textured, without plasticity and with an opaque appearance, reducing the final strength of the restoration and increasing the expansion and porosity, predisposing it to fractures, marginal degradation, and corrosion of the surface [6, 8, 9, 14, 20]. It can also be a

observed the increase of the setting expansion, leading to undesired stress on the restoration. When the dropping test is performed, the material will spread. In relation to overtrituration, it can be observed that the resulting material is very shiny but with low plasticity and some heated, increasing the creep and shrinkage and reducing the setting expansion [6, 8, 9, 14, 20]. When the dropping test is performed, the material does not change its shape. On . Fig. 11.10a–c, it can be observed the characteristics of an amalgam with different degrees of trituration.  

b

c d

11 e

f

g

h

..      Fig. 11.8  Measurement of the alloy:mercury ratio and hand trituration of the amalgam. a Scale on the horizontal position; b, c mercury placed inside the dish of the scale; d adjust of the weight so that it come back to the horizontal position; e mercury transferred to the glass mortar; f the removal of mercury makes the scale lean to the

weight side; g, h pouring of the alloy inside the scale until it is once again on the horizontal position; i Alloy transferred into the mortar; j, k trituration until the point where the material begins to loosen to the mortar walls; l–n removal of the excess of mercury; o material transferred into a rubber dappen dish

387 Amalgam Restorations

i

j

l

k

n m

..      Fig. 11.8 (continued)

11

388

C. R. G. Torres et al.

An enough amount of amalgam must be triturated to fill the preparation. However, it is not recommended to triturate more than two spills at a time so that the material can maintain the adequate plasticity for condensation. In large cavities, new spills should be triturated only when the previous one has been completely condensed. The next step is to start the condensation, which has the purpose of adapting the material into the preparation. That will bring the particles close to remove the excess mercury, reducing porosities and producing a solid metal mass that can be carved and polished [6]. To take the material into the cavity, amalgam carriers are used, as shown in . Fig. 4.50a. The application and condensation of amalgam must start in the proximal boxes, pressing the material toward the line and point angles, retentions, and gingival wall (. Fig. 11.6i–l) [10, 16]. Several consecutive layers can be applied and correctly condensed into the preparation until the complete filling

o

 

 

..      Fig. 11.8 (continued)

a

b

11

c d

..      Fig. 11.9  Mechanical amalgamator devices. a Device for the alloy and mercury; b containers to place the materials; c device for pre-proportioned capsules; d opened capsule showing the alloy and the pre-dosed mercury

389 Amalgam Restorations

a

b

c

..      Fig. 11.10  Aspects of amalgam with various degrees of trituration. a under triturated; b ideal trituration; c over triturated

with excess (. Fig. 11.6m–p). The condensation effectiveness is related to the diameter of the instrument’s nib, the direction, and the amount of force applied [6].  

>> The purpose of condensation is to adapt the material in the preparation, bring the particles close together to remove the excess mercury, reduce the porosities, and produce a solid metal mass that can be carved and polished.

The amalgam condensation must be finished before the initial setting time, which is around 3 min [20]. The amalgam alloy can be classified on fast, regular, and extended setting time. The setting time of the alloy can be adjusted by the manufacturer through the thermal treatment of the alloy. The fast-setting amalgam must be condensed in 2.5 min, the regular in about 3.5 min, while the extended in about 5  min. The condensation of the material after this period leads to a serious drop on the final strength of the restoration [6]. Tip

The condensation must be started in the proximal boxes, pressing the material toward the line and point angles, additional retentions, and gingival wall, being finished before the setting time.

The condensation of the amalgam can be performed manually or using mechanical condensers. The mechanical condensers may work by impact or vibration [12]. The ones that work with impact, known as pneumatic condensers, are preferred because they produce an excellent condensation and reduce the necessary load applied by the dentist to reach a satisfactory result. However, they are applied only to ease the dentist’s work because they do not produce better results than the manual condensation [6, 20]. A disadvantage of the mechanical condenser is the possibility of damage to enamel margins of the preparation with the condenser’s nib,

besides  the patient complain related to the impact feeling [16]. On the other hand, condensation by vibration using ultrasonic devices, even though produces good results, leads to the formation of small mercury particles which spread in the air and evaporate and may be inhaled by the patient or by the dentist [9]. For this reason, this technique is not recommended. When mechanical condensers are used, the same rules applied for the manual condensation must be followed, except by the fact that the manual load will be reduced and compensated by the increase of the frequency produced by the instrument [6]. In relation to the hand condensation, instruments with flat nibs with several different diameters are used. There are three most common sets of condensers, as can be observed in . Fig. 4.47. The condensers created by Black have nibs with a cylindrical shape with several sizes and shapes, and the set is composed by seven instruments. The instruments created by Höllenback present conical trunk-shaped nibs, and the set is composed by five instruments. The Ward instruments have inverted conical trunk-shaped nibs with the larger diameter facing the end tip and a narrow shank (. Fig.  11.11). The advantage of this instrument is the fact that it simplifies the removal of the superficial mercury-rich amalgam during the condensation procedure, because the material flows over the nib and can be gradually removed [9, 14]. To obtain a proper condensation, the material must undergo the strongest load possible applied by the instrument nib. Although the ideal condensation load is about 6.8 kg, it is almost impossible to reach it clinically. Some authors recommend a load of about 4.5 kg, although a load of 1.5– 2.5 kg is considered acceptable [8, 12, 19]. The condensation load can be tested by pressuring the condenser instrument toward the regular scale. For smaller condensers, the load can be reduced. A relevant factor is the relation between the diameter of the instrument’s nib and the final pressure applied over the material. Considering the application of a 2 kg load in an instrument with a nib of 2 mm in diameter, the resulting pressure will be 62 kg/cm2, while the same load when applied in an instrument with a nib of 3.5  mm in  

 

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C. R. G. Torres et al.

..      Fig. 11.11  Ward condensers set with different nibs’ diameter

11

diameter will result in a pressure of only 20.8 kg/cm2. When the diameter of the condenser is duplicated, it will be necessary 4 times more load to reach the same pressure per unit of area [16]. On real life, the load applied must be higher as possible but keeping the comfort of the patient. It is known that the greater the condensation load, the greater the final resistance of the restoration, because it decreases the total amount of mercury and reduces λ2 phase, besides reducing the surface porosity. Good condensations can almost double the fracture resistance of the amalgam restoration. The other factors that influence the condensation technique are the types of alloy. The amalgam prepared with lathe-cut and admixed alloys is easier to condense, and a sequence of condensers from the smaller to the larger must be followed, although more load is required to obtain a proper adaptation to the preparation angles and walls in relation to the spherical alloys. However, amalgams prepared with purely spherical alloys are more difficult to condense. When the pressure is applied by the condenser nib, the particles slide over each other, impairing the procedure, especially if small condensers are used, because they tend to penetrate the material and do not produce enough pressure to adapt the amalgam to the preparation [16]. For that kind of alloys the condensers with the largest diameter capable to penetrate the preparation are used since the first increment, because the material easily adapts to the walls and angles [9, 16, 19]. This characteristic of the material can result in difficulty to obtain proximal contact points of the restorations with the adjacent teeth. For this reason, purely spherical alloys are scarcely found on the market today. The condensation of amalgam prepared with lathe-cut or admixed alloys must begin with the smallest condensers, which are able to reach the gingival wall and press the material toward the preparation angles (. Fig.  11.6j, k) [9]. The material is applied in small increments, of about 1–2  mm thick, until the complete filling of the preparation. Each increment should fill a maximum 1/3 or half of the prepara 

tion depth. Each condensation mark over the amalgam overlaps the anterior one, to assure that the entire material is well condensed [9, 16]. The condenser nib must be directed toward the cavity angles, avoiding the lack of adaptation at those areas [14]. During the condensation, the excess mercury that occasionally may migrate to the surface, with a shiny wet appearance, can be gradually removed, using a dentin spoon or even the sides of the Ward-type condensers, which is moved toward the surrounding walls of the preparation and pulled outward [6, 13]. The excess mercury on amalgam increases the marginal degradation, staining susceptibility, corrosion, and general degradation, reducing the compressive strength and resulting in premature failure of the restoration [6]. The residual mercury content of amalgam on different areas of the restauration was determined in some studies, showing that the marginal areas and thin edges have a larger amount than others, explaining its higher fracture rate, small tensile strength, and greater degradation [21]. For this reason, bevels must not be made on the occlusal cavosurface angles of the preparation [6]. Each amalgam layer must be very well condensed before another portion is added [6]. A mercury excess of only 1% in the amalgam reduces its compressive strength in about 45–60 kg/cm2. The removal of excess mercury improves the mechanical properties and decreases the corrosion and marginal degradation, due to the reduction of the mercuroscopic expansion in the final restoration [14]. During the preparation filling with amalgam, when it is becoming full, the use of small condensers is hard because it tends to penetrate into the material [6]. Therefore, larger condensers are used, until the preparation is overfilled. A minimum amalgam excess of 1 mm is left over the cavosurface angles, allowing the carving procedure to remove the mercury-rich superficial layer, resulting in a restoration surface with better physical properties [6, 13, 16]. At this stage the material must be condensed toward the margins, perpendicularly to the external surface of the enamel (. Fig. 11.6o, p), assuring a perfect adaptation of the restorative material, producing a restoration without gaps and hollow spaces, and reducing the microleakage [9, 16]. At the marginal ridge region, the material should also be applied in excess, higher than the height of the adjacent tooth’s marginal ridge. If the preparation is very large, it is recommended to triturate separated spills to allow proper condensation during the setting time [12]. In general, 4.5–5.5 g of the amalgam can be condensed at this time period. This amount is enough for a medium-sized occlusal preparation [6, 12]. Two or three spills may fill a regular two-surface Class II preparation. Some large restorations may require 10–12 spills. If the spill is not condensed in 3 min, it must be discarded and another one prepared [12]. In each minute that passes further than the ideal setting time, the remaining material that has not yet been condensed presents a strength reduction of about 10% [1]. If a material on an advanced stage of crystallization is  

11

391 Amalgam Restorations

used, it will not bond chemically to the portion that has already been condensed and will be difficult to be adapted to the preparation walls and angles and reduce the final strength of the restoration [16]. At these conditions, the material has reduced plasticity, adversely affecting the adaptations and increasing the final mercury content [9]. A defective condensation will reduce the strength and increase the creep, corrosion, and microleakage. 11.3.1.3  Pre-carve Burnishing

After the end of the condensation, the pre-carve burnishing, which is a type of condensation, must be performed before the carving procedure. For that, large instruments with rounded edges are used, such as those shown in . Fig. 11.12a– c. It is performed by moving the instrument from the restoration toward the margins, with a strong pressure, in a way that eventually the instrument touches the incline of the cusp but not the margins [9]. The pressure applied is similar to the one used during the condensation (. Fig. 11.6q) [16]. The aim of the pre-carve burnishing is to optimize the condensation, making the excess mercury flow to the surface and be removed during the carving, leaving a margin with a more dense and strong amalgam [14]. Furthermore, it also compacts the particles to reduce the porosity [9].  

 

11.3.1.4  Carving

The carving can begin at the same moment that the amalgam is hard enough to resist to a soft pressure of the instrument [6, 12]. When carving, it is possible to hear a “squeaking” sound [12]. Most material can be carved up to 7–8 min after the trituration although the same may vary from 4 to 13 min [9]. The main goal of this procedure is to restore the lost shape and function. Therefore, a deep carving may result in the weakening of the restoration margin, predisposing it to chipping due to the small thickness of the restorative material on those areas, according to what has already been mentioned in 7 Chap. 6 [9, 13, 16, 20]. This way, the sculpture of the complex small anatomic details is not as important as the major ones which determine the tooth function [9]. Especially on cases of teeth with high cusps, where there is  

a

b

c

the tendency to produce very thin margins of restorative material, which are prone to fractures, a shallow sculpture is more adequate, reducing the probability of marginal chipping. On the other hand, the permanence of flashes of restorative material further than the cavosurface angle, over the tooth surface, is completely unacceptable because it will easily fracture, creating an area adequate for biofilm deposition [9, 16]. The contour of the preparation and the location of the occlusal contacts, before the restorative procedure, should be kept as a mental image before the amalgam condensation, to simplify the location of the margins during the carving process, avoiding amalgam flashes and helping the occlusal adjustment [16]. For carving of the restoration, instruments with cutting edges are used, as can be seen in . Fig. 11.13a–g, and they must always be sharp [12]. There are several types available on the market, and the choice will be more related to a personal opinion. However, the Hollenback carvers No. 3 and No. 3S are the most commonly used. The remainings of the cusps and ridges and the adjacent teeth are used as guides to shape the restoration anatomy [6]. The sculpture of a restoration that involves the proximal ­surface must begin in the region of the marginal ridge, carving the occlusal embrasures [10]. The exploratory probe is positioned touching the matrix band, leaning at an angle of about 45° in relation to the long axis of the tooth, and the instrument moved in the buccolingual direction (. Fig. 11.6r) [9, 16, 19]. This procedure also removes the excess of amalgam in contact with the matrix, avoiding its fracture during the band removal [13, 16]. The height of the ridge must be similar to the one of the adjacent tooth. Then, the carving of cuspal inclines is performed. For that, the instrument is placed in a way that the cutting edge is perpendicular to the preparation wall, touching the cavosurface angle and resting on the surface of the cuspal incline. The tip is placed on the region of the planned central groove, and it should be moved toward the mesiodistal direction, parallel to the margins, with small strokes, initially on the buccal cusps and then on the lingual ones or vice versa (. Fig. 11.6s) [6, 10, 16, 20]. This way, there is a possibility to correctly define the other grooves and the triangular and central fossae. During the carving, it is important to avoid the displacement of the central groove toward buccal or lingual sides because it may weaken the restoration [9, 13]. A rough carving can be performed quickly, and the band is removed to allow a more precise sculpture of the occlusal surface. Another option is to use Frahm carver instrument set. The No. 2 is used on a similar way to the Hollenback carver, with the cutting edge resting on the remaining cuspal incline, with mesiodistal movements, to create the central groove and restore the lost portion of the cuspal inclines (. Fig. 11.6b′) [13]. The instruments No. 6 and No. 10 are moved on the buccolingual direction to create the buccal and lingual grooves (. Fig. 11.6c, d′). The discoid-cleoid carver may also  

 

 

 

..      Fig. 11.12  Amalgam burnishers. a No. 33 Bennett; b No. 29 egg-shaped; c No. 6 Hollenback

 

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C. R. G. Torres et al.

a

11

b

c

d

e

f

g

..      Fig. 11.13  Amalgam carvers. a, b No. 3S and No. 3 Hollenback; c–e No. 6, No. 2, and No. 10 Frahn; f cleoid; g IPC 1

be used as observed in . Fig.  11.6z, a′. The discoid side is used to start the sculpture on the region of the triangular fossa, while the cleoid works similar to the Hollenback No. 3 carver [13, 16]. The Shoshan-A carver can be used like a Hollenback carver. The carving of the developmental grooves is essential to recreate the anatomy of the occlusal surface. The carved restoration must work correctly and not cause discomfort to the patient [6]. After carving, the outline of the restoration margin must match the outline of the preparation cavosurface, showing a regular contour with soft curvatures. A larger and irregular outline of the amalgam restoration means under-­ carving and requires additional sculpture while the material did not set, or finishing with rotary instrument after setting [16]. If the carving is performed quickly, the visualization of anatomic details can be improved by rubbing a small cotton ball over the restoration, showing those that need to be improved (. Fig. 11.5e′). All amalgam residues are removed with the aid of a powerful vacuum suction system or soaked gauze [16]. It is important to remove the matrix band as soon as possible, to have enough time to remove excess material on areas difficult to access, such as the proximal region, and to finish the carving on the occlusal surface [16]. For that, the pad of the index finger is to be placed over the occlusal surface to stabilize the band, while the matrix retainer is removed first, reducing the probability of restoration marginal ridge fracture in relation to when the entire set is removed at once. Otherwise, the rotation movement necessary to loosen the vise locking screw of the matrix retainer may fracture the  

 

amalgam recently applied [16]. The wedges are removed and afterward the band, rising each side of the band at a time, pulling it occlusally (. Fig. 11.6t–v) [6, 9]. The movement of the matrix should primarily be toward the buccolingual direction, while the matrix slides toward the occlusal surface [19]. Some authors recommend to cut the matrix next to the tooth on the lingual side and then pull it toward the buccal side to reduce the risk of fracture of the marginal ridge [10, 13, 16, 19]. When a custom-made matrix is used, it must be cut with scissors to be removed [13]. Some dentists prefer to leave the wedge in position to maintain the tooth separation while the matrix is removed [16]. If the amalgam restoration fracture during the matrix removal, the defective area needs to be repaired as it was a small restoration, and the adequate depth and retention will need to be prepared, sometimes completely inside the amalgam restoration that already exists. If necessary, another band is placed, and a new amalgam is condensed directly on the defects, bonding to the existing material [16]. After the removal of the band, it is possible to improve the carving once there will be a better access to every region. The first step is to check the height of the marginal ridge, using a carver placed on the horizontal direction, in a way the one side is held over the intact ridge of the adjacent tooth. It is moved in the buccolingual direction, making the marginal ridge of the restored tooth to have the correct height (. Fig. 11.6w) [19]. The excess on the proximal region, specially on the buccal or lingual margins, near the buccogingival and linguogingival line angles, can be removed with a Hollenback carver instrument or an interproximal carver  

 

393 Amalgam Restorations

(DeMeo or IPC) (. Fig. 11.6x). Even if the wedge is correctly applied, the gingival margin may require to be carved to remove the excess [6, 10]. Overhangs may occur as small portions of amalgam had been projected further than the gingival margin. The wedge prevents the occurrence of large excesses on the periodontal area, but it does not guarantee 100% success on the formation of a smooth and exact restoration margin [6]. The proximal area of the amalgam restoration should always be visually evaluated, directing the light to the interproximal area, through a clinical mirror, observing it from the opposite side, to check the contour and to confirm the presence of proximal contact (. Fig. 11.6f′). It is known that the contact is proper when no light is seen on the corresponding area.  

 

11.3.1.5  Post-carve Burnishing

The next step is to burnish again the restoration after the carving, which consists rubbing small burnishing instruments over the restoration surface with a gentle pressure, avoiding deforming it, adapting the particles that were displaced during carving (. Fig. 11.6g′, j′) [8, 9, 14, 16]. The aim of this procedure is to reduce the superficial porosities and create a smoother surface, decrease the superficial corrosion, improve the marginal adaptation and consequently reduce the microleakage, and reduce the residual mercury content on the margins, increasing the marginal integrity, besides increasing the surface microhardness [2, 3, 9, 11]. The postcarve burnishing produces a surface with silky appearance, reducing immediately the roughness from 4 to 5 μm on the carved amalgam surface to less than 0.4 μm on the burnished amalgam. The interproximal area can be properly burnished by rubbing softly the surface with the side of an exploratory probe or a No. 6 Hollenback burnisher (. Fig.  11.5g′) [9]. The occlusal surface should be thoroughly burnished, avoiding to change the carved morphology. In addition, it is important to check and to smooth the proximal surface with a dental floss (. Fig.  11.5k′, l′). It is made carefully for not breaking the interproximal contact that has recently been created, because amalgam is not completely crystallized. For that, the floss is taken to the contact area, initially embracing the adjacent tooth and pressing this tooth, instead of the restored one, while it is moved toward the contact area. When the floss is in the interproximal space close to the gingiva, it embraces around the restored tooth and is moved in the occlusal and gingival direction, checking if there is excess and smoothing the amalgam on the proximal surface. If the excess exist and it is not removed by the floss, the IPC can be used until a correct margin is obtained [16].  

 

 

11.3.1.6  Occlusal Adjustment

The next step is to remove the isolation and perform the occlusal contact adjustment, using a thin double-color articulating paper and Miller forceps [8, 10]. First, one of the colored sides, the red side for instance, is placed facing the restored tooth, and the patient is asked to perform the protrusion and lateral movements, to mark the contacts during the disocclusion guides. Then, the opposite side of the paper

is placed facing the restored tooth, and the patient is asked to close the mouth in the maximum intercuspation position (MIP). The contacts in MIP and the ones that occasionally happen during the protrusion and lateral movements are analyzed and adjusted, removing any premature contacts that may lead to discomfort and fracture of the restoration [9]. Contacts during excursive mandibular movements must be removed, while the contacts on MIP can be preserved, since they are not premature [19]. When anesthesia has been used, it is difficult for the patient to know when the teeth are in contact and whether there are premature contacts or not. Therefore, it is necessary to use the marks left by the articulating paper to perform the adjustment. It is important to evaluate if the contacts that were occurring before the restoration are still happening or if only the new restoration is contacting the opposite tooth, which indicates a premature contact at this area [16]. The contact load is recognized by the intensity of the mark left and by the fact that on the stronger ones the center has no color. The strong contacts are reduced until all marks are similar, and the contacts previously observed before the preparation can be seen [16, 19]. The patient is instructed to close the mouth slowly and to stop as soon as any contact is noticed [16]. Then, the contacts are evaluated and adjusted in case they are producing interference. The articulating paper use is repeated, and carving is performed until the patient is able to properly close the mouth, without interference, with the occlusion similar to the one before restoration. After the adjustment, the surface must be burnished again [16]. While carving, stable contacts must be created on correct places. These contacts should be perpendicular to the direction of the occlusal loads wherever possible. If the contact is on an inclined plane, and not perpendicular to the occlusal load, the dentist should try, while removing the excess of the amalgam, to remove the undesired portion from the contact area, on the incline, or carve a platform perpendicular to the load. In addition, an over-carved restoration, without occlusal contacts, may result in an undesired tooth extrusion [16]. If the amalgam already is on an advanced stage of crystallization, the adjustment must require the use of a finishing bur [16]. A rotary instrument may be used to finish the carving if the amalgam has already hardened in such a way, that the necessary force to carve it with hand instruments may fracture portions of the restoration. Round- or flame-shaped burs may be used to recreate the tooth anatomy [16]. However, the ideal is that all immediate adjustments would be performed with hand instruments. As the amalgam strength 20 min after the sculpture is of only 6% of the final one after 1 week, the restoration must not undergo immediate strong chewing loads, and the patient must be warned not to chew over this tooth. After about 8 h, the material presents 70% of the final strengths, and the patient can already normally use the restored tooth. However, the polishing of the restoration should only be performed after at least 24–48 h, even though the best would be after several days [8, 10, 12, 13, 16]. In some cases, the maximum strength is only reached 30 days after finishing the restoration.

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11.3.2  Restoration of Compound Class I

Preparations

Due to the leaning of the buccal surfaces of the mandibular molars and lingual surfaces of the maxillary molars, the use of a universal matrix will not result in the correct adaptation of these surfaces, making the restorative procedure more dif-

11

ficult [16]. On those cases, the matrix proposed by Barton can be applied (. Fig. 11.14a, u) [16]. First, the tooth is surrounded by a universal matrix with a matrix retainer or a custom-made spot-welded or riveted matrix. When a universal matrix is applied, the matrix retainer should be positioned on the opposite surface to the one that will be restored. A small piece of the metallic band must be cut, in a way that it  

a

b

c

d

e

f

..      Fig. 11.14  Preparation of Barton matrix. a Application of the universal matrix; b cutting the Barton matrix; c, d placing of band; e adaptation with the No. 6 Hollenback burnisher; f displacement with the exploratory probe; g insertion of a wedge with melted compound; h adaptation over the lingual surface; i checking the adaptation with

an exploratory probe; j, k condensation of the amalgam; l burnishing; m, n occlusal carving; o matrix removal; p carving of the lingual surface; q carved restoration; r, s burnishing; t immediate aspect; u result after the polishing

395 Amalgam Restorations

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..      Fig. 11.14 (continued)

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u

..      Fig. 11.14 (continued)

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397 Amalgam Restorations

is slightly larger than the height of the clinical crown, going beyond the gingival cavosurface angle (. Fig.  11.14a). The corners that will be placed facing the gingiva are to be cut avoiding injuries to the periodontal tissue (. Fig. 11.14b). It is applied between the universal matrix and the tooth surface (. Fig. 11.14c, d). Then, a No. 6 Hollenback burnisher is used to correctly adapt it to the surface (. Fig. 11.14e). A wooden wedge with small dimensions or a piece of 1.3 cm of round toothpick is selected, which must be covered with melted low fusion compound, light-cured gingival barrier  or PVS bite registration material [16]. The Barton matrix is displaced with an exploratory probe, and the wedge is inserted into the position, stabilizing the set (. Fig. 11.14f–h). If the wedge is higher than the matrix, it must be cut, so it will not adversely affect the next step. The adaptation of the matrix on the cavosurface angle is checked with the exploratory probe (. Fig.  11.14i), and then the amalgam is condensed with excess (. Fig.  11.14j, k). Then, the pre-carve burnishing is performed (. Fig. 11.14l), and the carving of the region near the matrix starts with an exploratory probe (. Fig. 11.14m) and the occlusal surface with a carver (. Fig.  11.14n). The matrix is completely removed, and the carver is finished (. Fig. 11.14o–q). After that the post-carving burnishing is performed (. Fig. 11.14r–t).  

 

 

 

 

 

 

 

 

 

 

 

the retentions with a small condenser and then toward the mesial and distal walls. After that, the central part is filled [16]. However, on the case of large preparation, the condensation becomes harder, because the amalgam tends to escape, due to the fact that the applied portions are not held by the surrounding walls or because the axial wall is convex [16]. On this case, a window matrix must be prepared, as proposed by J. M. Prime (. Fig. 11.5a–o) [8, 16, 20]. To do that, a universal matrix is placed around the tooth, with a matrix retainer located on the opposite surface to the one that will be restored (. Fig. 11.15b). The position of the preparation is marked on the band with an instrument with a sharp tip (. Fig. 11.15c). It is then removed, and a “window” is opened with a cylinder diamond point, with dimensions smaller than the preparation but large enough to allow the application of the restorative material (. Fig. 11.15d). The matrix is once again placed in position (. Fig.  11.15e). In case it is not stable enough, wedges may be placed in the interproximal spaces on both sides [20]. Then, the application of the restorative material into the preparation is started, condensing it toward the mesial and distal walls, with a small diameter condenser, until the preparation is completely filled (. Fig.  11.15f–h). The condensation on the region of the window opening can be performed with an instrument of a larger diameter (. Fig. 11.15i). The matrix is immediately removed, and the restoration is burnished, following the carving of the surface in two planes, according to the direction of the remaining surface, reproducing the curvature of the region (. Fig. 11.15k, l). The under-contour will result in the trauma of the gingiva, while the over-contour will result in the reduced gingival stimulation and self-cleaning of the tooth surface during the mastication [16]. Then, the burnishing of the area is started with the No. 6 Hollenback burnisher or No. 33 Bennett burnisher (. Fig.  11.15m, n). Egg- or round-shaped burnisher must not be used because they may deform the restoration and result in a concave contour. The retraction cord interferes on the carving of the gingival margin. On this case, first, a rough carving must be performed, and then after the removal of the cord, it can be improved [16].  

 

 

 

 

 

 

11.3.3  Restoration of Class V Preparations

(Site 3)

The amalgam restorations on Class V preparations are indicated on areas where esthetics is not a concern, the access and the visibility are limited, and the moisture control is difficult [16]. The cavosurface angles of the gingival wall in Class V preparation are many times located inside the crevice, beyond the gingival margin. On those situations it may require the displacement of the gingiva with a retraction cord or a rubber dam isolation, associated with cervical retraction clamps, to allow the access while controlling the crevice fluid flow. For the rubber dam isolation, the Schultz or W8A clamp may be used [6]. Sometimes it is necessary that the surgical displacement of the gingiva associated with relaxing incisions allows the access to those areas. The retraction cord must be packed before the preparation to reduce the possibility of damage to the gingiva. In general, about 8–10 mm of cord is used, and it must always be longer than the mesiodistal dimensions of the preparation. The cord thickeness must be adequate to allow the packing into the crevice. It may be used alone or impregnated by a homeostatic solution and inserted into the sulcus with rounded tip of a retraction cord packing instrument. >> The Class V amalgam restorations are only indicted on areas where esthetics is not a concern, the access and the visibility are limited, and the moisture control is difficult.

 

 

Tip

During burnishing of Class V restorations, egg- or round-shaped burnisher should not be used, because they may deform the restoration and result in a concave contour.

11.3.4  Restoration of Horizontal Slot

Preparations

For restorations of the horizontal slot preparations with amalgam, the S-shaped matrix is the most recomended (. Fig. 11.16a–n) [17]. About 2.5 cm of matrix band is precontoured with the handle of a clinical mirror (. Fig. 11.16b– e). The band is contoured touching the surface opposite to  

Most Class V preparations may be restored without the use of matrix. On this case, the amalgam is condensed first toward

 

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a

b

c

d

e

f

g

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..      Fig. 11.15  Restoration of a large Class V preparation with a window matrix. a Tooth preparation; b application of the universal matrix around the tooth; c marking the place of the preparation; d opening of the “window” with the diamond point; e window matrix positioned; f application of amalgam; g–h condensation of the

amalgam in the areas covered by the matrix; i Condensation of the amalgam after the entire filling of the preparation; j pre-carve burnishing; k, l carving in two planes; m, n post-carve burnish; o finished restoration after the polishing

399 Amalgam Restorations

i

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..      Fig. 11.15 (continued)

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must be avoided the contact of heated instrument to the preparation walls, as it could harm the pulp. The material is condensed, and the carving can start with the exploratory probe, toward the matrix band (. Fig.  11.16j, k). Then, the Hollenback carver is used. The wedge and the band are removed, and the carving is finished with an IPC or thin exploratory probe (. Fig. 11.16l). The restoration is smoothened with a dental floss to produce a better cervical margin (. Fig. 11.16m).

the preparation access, passing through the proximal surface and curved over the smooth surface of the adjacent tooth (. Fig. 11.16f). It is placed in the interproximal space, and a wedge is inserted through the opposite side of the preparation access, being stabilized with compound (. Fig. 11.16g, h). If the internal contour of the matrix is not correct, an amalgam burnisher can be heated and placed inside the preparation, rubbing it toward the matrix, softening the compound and allowing the correct contour to be obtained. It  

 

 

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a

b

c

d

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..      Fig. 11.16  Horizontal slot restoration with the S-shaped matrix. a Tooth preparation; b, c first folding of the band; d, e second folding of the band; f matrix in position; g, h Stabilization with compound; i

finished matrix; j–l condensation and carving; m removal of excess with dental floss; n polished restoration

401 Amalgam Restorations

g

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..      Fig. 11.16 (continued)

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11.4  Finishing and Polishing

tact point, it can be necessary to cut the strip to make it narrower. The overhang must be completely removed. When The instruments and materials necessary for performing fin- it is not possible, the entire amalgam from the proximal box ishing and polishing of amalgam restoration are described must be removed and the restoration replaced. On the occlusal, buccal, and lingual surfaces, multibladed here: burs are used with air and water spray [9]. The regular burs 55 Micromotor and contra-angle handpiece have 6 blades, while the multibladed ones can have 12–30 55 Clinical mirror blades. The burs are placed parallel to the tooth surface on 55 Tweezers the region of the margins, to prevent unnecessary removal of 55 Double-ended No. 5 exploratory probe amalgam [9, 16]. Any premature contacts on the recently 55 Miller articulating paper forceps made restoration can be easily identified due to its shiny 55 Thin articulating paper (> Unnecessary exposure to mercury must be avoided – working on a well-ventilated office, choosing pre-proportioned capsules, and correctly storing the residues.

Other caution in relation to the use of the amalgam is  to avoid its contact with a wound on the mucosa, as well never hurt the mucosa during the application of the material. If the amalgam comes in contact with the wounded tissue, it may become encapsulated and result in a tattoo, as can be seen in . Fig. 11.22.  

Conclusion The use of dental amalgam can produce strong and long-­ lasting restorations on the posterior teeth. The knowledge about material properties and the restorative techniques were presented. The details about the steps of matrix and wedge placement, trituration of mercury and alloy, condensation, pre-carve burnishing, carving, and post-carve burnishing are the essential information. The finishing and polishing techniques were also described, being very important on the restoration durability. The controversy about amalgam use in relation to mercury toxicity was discussed, showing that it is completely safe when correctly used. However, its metallic color and lack of bonding to the tooth structure have dramatically reduced its use worldwide. Despite that, it is an excellent material and still an option for areas where esthetics is not a concern.

1. Anusavice KJ. Phillips science of dental materials. 11th ed. London: Elsevier; 2005. 2. Arcoria CJ, Kelly GT, Icenhower TJ, Wagner MJ.  Microleakage in amalgam restorations following burnishing, polishing, and time-­ varied thermocycling. Gen Dent. 40:421–4. 3. Ben-Amar A, Serebro L, Gorfil C, Soroka E, Liberman R. The effect of burnishing on the marginal leakage of high copper amalgam restorations: an in  vitro study. Dent Mater. Elsevier. 1987;3:117–20. https://doi.org/10.1016/S0109-5641(87)80042-8. 4. Bogacki RE, Hunt RJ, del Aguila M, Smith WR.  Survival analysis of posterior restorations using an insurance claims database. Oper Dent. 27:488–92. 5. Fichmann DM, Santos W.  Restaurações à amálgama. São Paulo: Savier; 1982. 6. Gilmore HW, Lund MR.  Operative dentistry, Saint Louis: Mosby; 1973. 7. Healey HJ, Phillips RW. A clinical study of amalgam failures. J Dent Res. SAGE PublicationsSage CA: Los Angeles. CA. 1949;28:439–46. https://doi.org/10.1177/00220345490280050301. 8. Hollenback GM. The economic value of amalgam in operative dentistry ant the technique of its use. J Am Dent Assoc. 1937;24:1318– 26. 9. Horsted-Bindslev P, Mjör IA.  Dentística operatória moderna. São Paulo: Santos; 1990. 10. Howard WW. Atlas of operative dentistry. 2nd ed. St. Louis: Mosby; 1973. 11. Kato S, Okuse K, Fusayama T. The effect of burnishing on the marginal seal of amalgam restorations. J Prosthet Dent. Elsevier. 1968;19:393–8. https://doi.org/10.1016/0022-3913(68)90042-5. 12. Markley MR. Restorations of silver amalgam. J Am Dent Assoc. Elsevier. 1951;43:133–46. https://doi.org/10.14219/JADA.ARCHIVE. 1951.0192. 13. Mondelli J, Franco EB, Pereira JC, Ishikiriama A, Francischone CE, Mondelli RL, et  al. Dentística: Procedimentos Pré  - Clínicos. São Paulo: Santos; 2002. 14. Neto NG, Carvalho RC, Russo EM, Sobral MA, Luz MA. Dentística Restauradora: Restaurações diretas. São Paulo: Santos; 2003. 15. Ring ME.  História Ilustrada da Odontologia. São Paulo: Manole; 1998. 16. Roberson TM, Heymann H, Swift EJ. Sturdevant’s art and science of operative dentistry. 5th ed. St. Louis: Mosby; 2006. 17. Roggenkamp CL, Cochran MA, Lund MR. The facial slot preparation: a nonocclusal option for Class 2 carious lesions. Oper Dent. 1982;7:102–6. 18. Schoonover IC, Souder W.  Corrosion of dental alloys. J Am Dent Assoc. Elsevier. 1941;28:1278–91. https://doi.org/10.14219/jada. archive.1941.0194. 19. Schwartz RS, Summitt JB, Robbins JW.  Fundamentals of operative dentistry. A contemporary approach. Chicago: Quintessence; 1996. 20. Simon WJ.  Clinical operative dentistry. Philadelphia: Saunders; 1956. 21. Swartz ML, Phillips RW. Residual mercury content of amalgam restorations and its influence on compressive strength. J Dent Res. 1956;35:458–66. ­https://doi.org/10.1177/00220345560350031801.

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Extensive Amalgam Restorations Carlos Rocha Gomes Torres, Shilpa Hanamaraddi Bhandi, and João Cândido de Carvalho 12.1

Introduction – 412

12.2

List of Complementary Materials – 413

12.3

Cuspal-Coverage – 413

12.4

Restoration of Lost Cusps – 415

12.4.1 12.4.2

 atural Retentions – 415 N Artificial Retentions – 420

12.5

Bonded Amalgam Restorations – 426

12.6

Restoration of Extensive Preparations – 426 References – 433

© Springer Nature Switzerland AG 2020 C. R. G. Torres (ed.), Modern Operative Dentistry, Textbooks in Contemporary Dentistry, https://doi.org/10.1007/978-3-030-31772-0_12

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Learning Objectives The learning objectives of this chapter are related to the following topics: 55 How to perform extensive preparations on posterior teeth, improving the retention and resistance of the amalgam restoration but also protecting the remaining tooth structure 55 Technique of cuspal-coverage of weakened cusps 55 Preparation of natural retentions (vertical walls, axial offset, locks, coves, dentin pins, slots, amalgapin, and pulpal chamber retention) 55 Preparation of artificial retentions (intradentinal pins and endodontic posts) 55 Technique for bonded amalgam restorations 55 Restorative technique of extensive preparations with lost cusps

12.1

12

Introduction

Due to its mechanical properties, amalgam restorations should always be held and protected by the remaining tooth structure. Amalgam has a high compressive strength but a low tensile strength. Therefore, it is capable to resist heavy occlusal loads, when the compressive stress is predominant, but may fracture on cases of cusp restoration, when the tensile stress can be strong. According to Barrancos Mooney, a restoration will be more fragile when a larger tooth surface needs to be restored, considering the extensive amalgam restoration as a semipermanent procedure [13]. In addition, on large cavities, proper occlusal anatomy and contour are sometimes hard to restore [18]. Ideally, when a cuspal restoration is required, an indirect or semi-direct restorations should be done, which may be produced with metal, ceramic, or indirect composite [18]. On the other hand, the economic reasons many times determine the choice of the restorative material to be used. Whenever it is not possible to perform an indirect restoration, a very good option is the dental amalgam [18]. When well-planned and done, an extensive amalgam restoration may show high durability [9]. For this, some procedures to promote resistance and retention can be performed, according to what will be presented next. The extensive amalgam restorations are indicated to young patients, whose teeth have not completely erupted, when it is not possible to perform a proper gingival displacement and isolation of the operating field. In addition, elderly and/or debilitated patients who would not bear a long treatment may also have their teeth properly restored with amalgam [18]. They can also be performed when the permanent treatment must be delayed, such as in cases where the patients have a great difficulty to control the biofilm, until they will be completely trained and motivated to control the caries disease, or on patients undergoing orthodontic treatment. The same way, when there is the intention to delay the treatment with a prosthetic crown or in the case of teeth with a pulpal or doubtful periodontal prognostic, the amalgam restorations are a very good option. The extensive amalgam restorations used tempo-

rarily may work as a core, during the tooth preparation for indirect restorations, especially for the cast metal ones. On those cases, the retentions prepared for the amalgam restorations must not be removed during the preparation for the indirect restoration [18]. There are some advantages of extensive amalgam restorations in relation to the indirect ones. The preparation is generally more conservative, the treatment requires a single dental appointment and is less expensive. In some cases, when the patient cannot afford the cost of an indirect procedure, amalgam may be the only available alternative to the extraction of severely damaged teeth [18]. The key to the success of the cuspal restorations is the complete understanding of the mechanical principles to be applied in the procedure. The preparations for amalgam restorations have traditionally been designed to obtain retention. The retention is defined as the prevention of restoration displacement in the direction of the long axis of the tooth when submitted to tensile forces. The resistance is defined as to avoid the displacement or fractures caused by oblique or compressive loads [17]. Although the retention form is important on the extensive amalgam restoration, an emphasis must be given to the resistance of the restoration and the remaining tooth structure [19].

Resistance is defined as to avoid the displacement or fractures of the restoration caused by oblique or compressive loads.

Retention is defined as the prevention of restoration displacement in the direction of the long axis of the tooth, when submitted to tensile forces.

The general principles of tooth preparation applied on an extensive amalgam restoration are basically the same of the regular-sized ones. The walls must be flat, uniform, and smooth, and the vertical surrounding walls must be parallel or convergent toward the occlusal surface, while the internal and gingival walls are parallel to the occlusal surface [18]. The line and point angles are round to dissipate the stress and improve the adaptation of the restorative material. However, to improve the resistance and retention, some changes are required. When the amalgam cannot be held and surrounded by healthy remaining tooth walls, its total volume must be increased, creating enough thickness to resist the occlusal loads [9]. There are two situations that the extensive amalgam restorations are indicated: the situations when the cusps are still present but are fragile and prone to fracture and the cases when the cusps have already been lost. Both situations are presented next. >> When the amalgam cannot be held and surrounded by healthy remaining tooth walls, its total volume must be increased, creating enough thickness to resist the occlusal loads

413 Extensive Amalgam Restorations

12.2

List of Complementary Materials

In addition to the materials and instruments indicated for regular-sized amalgam restoration, the following items are required for extensive restorations: 55 No. 329 or No. 330 bur 55 No. ¼ round bur 55 Self-threading pins and corresponding burs 55 Instrument to fold the pin 55 No. 141 riveting plier 55 Periodontal probe 12.3

The coverage of the weakened cusps reduces its risk of remaining tooth fracture and extends its clinical life. When this procedure is not performed, sometimes complex factures of the cusp can occur, invading the biological width and requiring periodontal surgery. Amalgam restorations with one or more covered cusps have a longevity increased up to 72%, after 15 years, and they do not show differences in relation to the smaller-sized restorations without the covering (. Fig. 12.1a–i) [18].  

Tip

When the amount of the lost tooth structure is more than 2/3 of the distance between the central groove and the tip of the cusp, its upper part should be removed and covered with the restorative material.

Cuspal-Coverage

As it has already been mentioned on 7 Chap. 6, when the amount of the lost tooth structure is more than 2/3 of the distance between the central groove and the tip of the cusp, its upper part should be removed and covered with the restorative material (. Fig. 6.25a, b) [18]. Amalgam restorations with cuspal-coverage or cuspal-capping significantly increase the fracture resistance of weakened teeth when compared with the amalgam restorations without coverage [12].  

 

If the tooth is correctly positioned, the supporting cusps are reduced in approximately 2 mm, while the non-­supporting cusps are reduced in about 1.5  mm. After analyzing the occlusal interrelationship, if there is enough space between the tooth to be restored and the opposing tooth, the reduc-

a

b

c

d

..      Fig. 12.1  Preparation with cuspal-coverage. a Tooth with defective restorations and recurrent caries; b removal of the caries tissue; c filling with GIC. It can be observed that the mesiobuccal cusp is fragile; d evaluation of the height of the cusps; e Determination of the amount

of the reduction; f evaluating the depth determined; g reduction of the marked depth; h finished preparation involving the buccal surface; i finished restoration

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e

f

g

h

12 i

..      Fig. 12.1 (continued)

tion may be smaller [18]. A useful procedure is to evaluate the height of the cusp and the location of its tips, in a way that it can be later carved to its original height. For that, a periodontal probe can be placed along the mesiodistal cusp ridges of the cusps to be covered, touching the tips of the cusps of the adjacent teeth and memorizing or registering in a paper the relation of the cusps with the probe (. Fig. 12.1d) [19]. If there is no adjacent tooth, the gingival margin can be used as reference. The determination of the amount of the reduction may be obtained with a relative precision by using rotary instruments with known dimensions. It is known that the heads of  

No. 1148 diamond point and No. 245 bur are 3  mm long, while the No. 1090A diamond point is 4 mm long. Initially, depth cuts are made to delimitate the reduction, with the instrument perpendicular to the long axis of the teeth (. Fig. 12.1e). Then, the instrument is positioned parallel to the long axis of the teeth to verify the amount of reduction, depending on the type of cusp to be covered (. Fig. 11.1f). After that, the instrument is once again placed perpendicular to the long axis of the tooth, and the depth cuts are connected (. Fig. 12.1g). The cut surface must be as flat as possible and parallel to the occlusal plane, to produce a good stress distribution. The cusp reduction may be sometimes made at the  

 

 

415 Extensive Amalgam Restorations

beginning of the preparation because it improves the access and visibility for the next steps [18]. Any sharp angle formed during the preparation is rounded to reduce the stress concentration in the amalgam, to increase the fracture resistance of the restoration and tooth, preventing the fracture of the remaining tooth structure. 12.4

the ones obtained using artificial materials, such as metallic pins, which are anchored in the dentin or inside the root canal. The retention characteristics must be distributed in all areas of the preparation and not concentrate in only one. It is known that more load is necessary to cause the displacement and the fracture of the restorations when the characteristics of the retentions are opposed to the direction of the loads [19].

Restoration of Lost Cusps

To restore teeth with lost cusps, the first step is to adapt the remaining tooth structure to the basic principles of dental amalgam preparations. First, the outline form of the preparation is defined, creating flat margins and walls, especially the gingival wall, which extend from the proximal surface region toward the buccal or lingual surfaces, helping to distribute the stress generated on the occlusal loads. On the areas where the remaining structures are more preserved, the general characteristics of the amalgam preparations are followed, considering the buccolingual dimensions when choosing the direction of the vertical surrounding walls, convergent to the occlusal surface or parallel to each other, according to what has been described on 7 Chaps. 6 and 10. On the other hand, the main challenge of the extensive amalgam restorations is to obtain a satisfactory retention. Due to the lack of natural adhesion of this material, the restoration retention must be mechanically obtained. However, some micromechanical retention can also be obtained with the bonding amalgam technique, which will be discussed further on. The amount of required retentions will depend on the amount of the remaining tooth structure of the tooth to be restored. When more structure has been lost, more auxiliary retentions are required. The mechanical retentions can be classified into natural and artificial. The natural retentions are the ones obtained through the specific characteristics of the preparation made on the remaining tooth structure. The artificial retentions are  

a

..      Fig. 12.2  a Axial offset; b peripheral axial offset

12

12.4.1

Natural Retentions

12.4.1.1 Direction of the Vertical Walls

The easiest way to obtain retentions for a restoration is to prepare the surrounding vertical walls convergent toward the occlusal surface, despite the depth of the preparation, or parallel to each other if it is deeper than wide. 12.4.1.2 Axial Offset

A method that may promote retention is the preparation of axial offset, according to what is shown in . Fig. 12.2a [17, 18]. This produces retentions by the presence of opposing axial walls, which hinders the rotation of the restoration. A study showed that axial offset may allow an effective retention even with a small depth, such as 0.75  mm [2]. The peripheral axial offset can also be used, which will also hinder the rotation of the restoration (. Fig. 11.2b) [19].  

 

12.4.1.3 Retentive Locks and Coves

Another possibility to obtain retention is the preparation of undercuts in the walls, such as locks and coves. Locks are prepared in a vertical plane and coves are prepared in the horizontal plane. The locks are prepared using rotary cone-­ shaped instruments in the line angle between the vertical surrounding wall and the axial wall (. Fig. 12.5j, k, o). The coves are prepared in the line angle between the vertical surrounding walls and the pulpal wall, at the region under the cusps because this area has a larger volume of dentin  

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(. Fig.  12.5l–o) [18]. Rotary short inverted cone or round instruments can be used, according to what was described on 7 Chap. 6 (. Fig. 6.44a, b).

larger dimensions on the horizontal plane (. Fig.  12.4). They are indicated on teeth with short clinical crowns and on cusps that have been reduced for capping with the restoration [18]. It can be made on the gingival walls of the preparations using short inverted cone rotary instruments, such Tip as the No.33½ or No.34 burs or the 1031 diamond point. They can be continuous or segmented, depending on the Locks are prepared in the line angle between the vertical amount of lost tooth structure [18]. It must be approxisurrounding wall and the axial wall, while coves are mately 0.5 mm wide in the entrance, according to the rotary prepared in the line angle between the vertical instruments used, and 0.6  mm wide on the base, with a surrounding walls and the pulpal wall, at the region under depth between 0.5 and 1  mm [7, 18]. Generally they are the cusps, because this area has a larger volume of dentin. between 2 and 4  mm long, depending on the distance between the vertical surrounding walls, especially when the gingival wall is long. It must always be made in dentin, at 12.4.1.4 Dentin Pins least 1 mm away the DEJ. Some authors prefer to start the When the tooth presents carious lesions shallow in dentin, preparation with a conical 169 bur, finishing it later to with fracture of the enamel on the tip of the cusps, the so-­ ensure the convergence of the slot walls, using an inverted called dentin pins can be prepared [13]. To choose this reten- cone instrument such as the No.33½ bur. They consider that tion method, a minimum of 2  mm of space must exist this technique allows a better control during the preparabetween the dentin wall and the opposite tooth, allowing the tion, due to the fact that the No.169 bur has a smaller cutnecessary thickness of restorative material. If this space does ting end than the No.33½ one. not exist, the surface must be cut with a cylinder-shaped As the retention will be produced by a projection of the rotary instrument. After that, the region around the tip of the amalgam restoration inside the dentin, its resistance is related cusp is cut, resulting in a pin shape, according to what is to the setting of the restorative material, which is completed shown in . Fig. 12.3. Additional retention coves can be pre- at least only 24 h later. Therefore, extreme care must be taken pared on the bases of the pins, using short inverted cone at the moment of removing the matrix band, because an rotary instrument. abrupt movement may lead to a fracture of the amalgam on the entrance of the slot [18].  

 

 

 

 

12

12.4.1.5 Slots

The retentive slots for amalgam restorations were proposed by Outhwaite et al. [15] and are prepared in dentin, with its

12.4.1.6 Channels for Amalgapin

The preparation of a channel, in which the amalgam is condensed, creating a retentive amalgapin, was proposed by Shavell [20] (. Fig.  12.5a–i). It is  indicated when the  

..      Fig. 12.3  Dentin pins

..      Fig. 12.4  Preparation of slots on gingival walls

12

417 Extensive Amalgam Restorations

gingival walls are small or when the maximum preservation of the remaining tooth structure is desired. They should be preferably made with a long inverted cone bur No. 329 or No. 330 or with a No. 1031 diamond point. A channel of 1.5–2 mm depth and 0.8–1 mm diameter must be prepared [7, 19]. The same way as the slots, the channels are made in dentin at least 1 mm away from the DEJ. One channel per lost cusp can be prepared, preferably on the region near the axial angles to avoid perforation on the furcation region. They have the advantage to require less removal of tooth structure than the slots, even though they also require careful removal of the matrix band to avoid amalgapin fracture. To avoid the pulpal or periodontal perforation during the channel preparation, it is important that the long axis of the rotary instrument is placed parallel to the nearest external surface of the tooth on that area. The place where the channel is going to be prepared can be initially marked with an indentation or starting point, using a No. 1011 round diamond point or No. ½ or No. ¼ burs. If the extenal surface  of the tooth close to the area where the retention will be prepared is exposed above the

gingival margin, the alignment of bur is easier. However, in most cases, the soft tissue avoids the visualization of the tooth surface adjacent to the area of the channel location. To place the rotary instrument in the correct alignment, it is inserted inside the gingival sulcus, in a way that it only touches the gingival cavosurface angle of the preparation (. Fig.  12.5c ). Then, the bur is rotated in a way that it is separated from the margin, indicating that only the tip is touching the external tooth surface (. Fig. 15.5d ). Then, it is rotated back slowly until it touches once again the preparation margin, giving certainty that it is parallel to the external surface of the tooth (. Fig. 12.5e ). This alignment must be memorized and kept. The instrument is then placed into the starting point, maintaining the correct alignment (. Fig.  12.5f ). The bur must come in and out turning, avoiding fracture inside the channel [2]. The channel is prepared with the depth corresponding to the length of the rotary instrument head that is 2  mm long (. Fig.  12.5g ). To finish the preparation, a bevel is performed at the entrance of the channel, increasing the thickness of the material at this area, reducing the stress concentration on the base of the pin [17, 19]. The  

 

 

 

 

a

b

c

d

..      Fig. 12.5  Preparation of amalgapin channel and other retentions on a preparation with lost cusps. a Basic preparation finished; b No. 329 bur and No. 1011 diamond point; c–e adjusting of the bur direction; f, g preparation of the channel; h bevel at the channel

entrance; i finished channel; j preparation of the retentive lock on the mesiofacial line angle; k retentive lock on the buccoaxial line angle; l-o preparation of coves under the cusps

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e

f

g

h

i

j

k

l

12

..      Fig. 12.5 (continued)

419 Extensive Amalgam Restorations

m

n

o

..      Fig. 12.5 (continued)

a

b

..      Fig. 12.6  a, b Channels for the amalgapin

Tip

No. 1011 or No. 1012 diamond point or the No. 1 or 2 burs can be used, depending on the channel diameter. On those channels, the amalgam condensation must be performed with a thin amalgam condenser, such as the No. 00 from Ward set, taking care at the moment of the matrix band removal to avoid the pin fracture [7]. In . Fig. 12.6a , b, some clinical examples of the amalgapin preparation are presented.  

As the retention provided by slots and amalgapins will be produced by the amalgam condensed inside some very small cavities, its resistance is related to the setting of the restorative material, which is completed at least only 24 h later. Therefore, extreme care must be taken when removing the matrix band, because an abrupt movement may lead to a fracture of the amalgam and total loss of retention.

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12.4.1.7 Pulpal Chamber Retention

On the cases of pulpless teeth, after endodontic treatment, the pulpal chamber can be used to obtain retention for the restoration, and the amalgam is condensed inside it. This technique can be recommended when the dimensions of the pulpal chamber are adequate, allowing proper  volume for mechanical retention of the amalgam. In addition, the thickness of the remaining dentin around the chamber must be sufficient to give the necessary fracture resistance to the tooth. A pulp chamber with a height of 4–6 mm is enough to allow satisfactory retention for a direct amalgam restoration (. Fig. 12.7a) [18]. If it is necessary to increase the retention, coves can be prepared in the chamber walls, using a short inverted cone rotary instrument. However, when the pulpal chamber height is less than 2 mm, the use or artificial retention should be considered. Before condensing the amalgam, it is convenient to apply a thin layer of GIC over the obturation of the root canals, to simplify a future access in case an endodontic retreatment is required. Another option is to completely fill up the pulpal chamber with GIC, building a kind of core, and then to prepare slots or amalgapin channels inside it (. Fig. 12.7b, c). This way, the GIC will chemically bond to  

 

a

the tooth, while the amalgam will be mechanically retained in the cement. This last technique has the advantage to simplify the access to the root canal, in case a retreatment is required. 12.4.2

Artificial Retentions

There are basically two types of artificial retention methods that can be associated with amalgam restorations, the intradentinal pins and the endodontic posts, which will be described next. 12.4.2.1 Intradentinal Pins

They are metallic pins which are fixed in the dentin and capable to anchor the restoration. They can be made of stainless steel, silver, platinum-iridium alloy, titanium, or gold. The main requirement is that they must be resistant to oxidation. The contact of the stainless steel with the amalgam generally results in its corrosion. For this reason, some stainless steel pins are coated with titanium oxide or gold [7]. They can be cemented, friction-locked, or self-threaded. They are generally indicated on the cases that there is little or no vertical

b

12

c

..      Fig. 12.7  a Application of the amalgam inside the pulpal chamber on a transversal section; b, c filling of the pulpal chamber with GIC associated with mechanical retentions

421 Extensive Amalgam Restorations

wall and when there is space for the pin [18]. The pin channel is prepared with a special twist drill, which cuts only on the tip, different from a regular dental bur which cuts on the sides too. Although the intradentinal pins were first described in the nineteenth century, it was Markley on the 1950s who popularized the concept of the cemented stainless steel pins on his lectures and articles [8, 10]. For its application, a channel slightly larger than the pin is to be prepared, of about 0.025 mm, with a depth of 3–4 mm [18]. Then, the cement is applied into the channel with a lentulo spiral filler and the pin is inserted. The friction-locked pins were proposed by Goldstein and require the preparation of a slightly undersized channel, of about 0.025 mm, with a depth of 2–4 mm. When pressed into the channel, due to the elasticity (resiliency) of the dentin, it penetrates under pressure. The friction-­locked pins produce 2–3 times more retention than the cemented ones (. Fig. 12.8a) [18]. The self-threading pins also use the elasticity of the dentin for its retentions since the drill used for the channel preparation is 0.038–0.1 mm smaller than the pin (. Fig. 12.8b) [18]. The diameter of the pin in relation to the diameter of the channel must be in a way that, the deformation produced at the moment in which it is threaded, stay  inside the elastic limit of dentin [19]. The use of this pin for amalgam restoration was first described on a scientific publication by Going, in 1966. They are the only ones that are still used (. Fig.  12.10a–l) [18]. The channel depth must be around 1.5–2  mm. The thread is created when the pin is threaded into the dentin. A larger retention may be attained increasing the channel depth [18]. On a comparative retention analysis, a study showed that the self-threading pin is 5–6 times more retentive than the cemented ones and 2–3 times more retentive than the friction-­ locked. Therefore, to obtain the same retention offered by 1 mm depth of the self-threading pin, it would be  

 

 

a

necessary to have a 2–3 mm depth for the friction-locked and 5–6  mm depth for the cemented [7]. Although the thicker pins produce more retention, they also create more stress. For this reason, the pins with smaller diameter are chosen, such as 0.48 and 0.61 mm. The pins with 0.48 mm of diameter are generally used because they are safer. However, the pins with 0.61 mm of diameter are maintained as backup in case the channel is over-enlarged or the thread was stripped during the application of a thinner pin (. Fig. 12.8b). Vertical and horizontal stress can be generated in the dentin when a self-threading pin is inserted. However, cracks on the dentin may be related to the diameter of the pin. The thicker it is, the more cracks it causes, although they are more retentive than the thinner ones [18]. Those cracks happen mostly if they are incorrectly applied, which can predispose the remaining tooth structure to fractures. Those stress and cracks can have small or no clinical significance on most cases or may be important when little dentin is available [18]. The main requirement to avoid those problems is the preparation of the channel in a region not closer than 0.5–1 mm of the DEJ or not closer than 1–1.5 mm of the cavosurface angle in case of no enamel in the margin. Other disadvantage of the pins is the fact that they make the restoration more fragile, because they are composed of a material with different physical characteristics from the amalgam [7, 18]. To apply the intradentinal pin, a preoperative radiography must be obtained, in such a way to analyze the tooth position and any  leaning, the preparation depth, and the extension of the pulpal chamber [7, 18]. The gingival sulcus must be evaluated with a periodontal probe, determining if there is some abnormal contour of the tooth structure, which may predispose the tooth to an external perforation [18]. Then, the number and location of the pins are planned, choosing the smaller number as possible, being usually recommended only one pin per lost cusp. However, the number of pins may vary according to the diameter of the pin, the  

b

..      Fig. 12.8  Intradentinal pins. a Friction-locked; b self-threading (1 and 2, hand wrench and standard pins with different sizes; 3, 4, and 5, self-shearing pins with different diameters attached to the chuck;  6 pin hand wrench connected to the chuck)

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amount of remaining tooth structure, and the use of other retention forms, besides the functional requirements of the restoration. In relation to the location, a distance of at least 3 mm must be kept among them. The larger this distance, the smallest the stress level in the dentin [19]. There are certain locations more indicated to insert a pin, while others must be avoided, as it can be seen in . Fig. 12.9. In general, the preferred pin location must be on the regions near the axial angles, due to the larger amount of the dentin between the external surface and the pulpal chamber, decreasing the risk of perforation [18, 19]. This risk is larger on the region of root furcation. On the mandibular molars, the regions between the mesiobuccal and mesiolingual roots as well as between the mesial and distal roots must be avoided, because a pin placed at this area may reach the furcation region. On the same way, the middle of the distal root should be avoided due to its concavity, which may also result in perforation. On the maxillary molars, the pin channel preparation on the region between the buccal roots and between the buccal and lingual one must also be avoided. The region of the middle of the lingual root, due to its concavity, may also be potentially dangerous. On the first maxillary premolars, the channel preparation between the buccal and lingual roots can also result in perforation [19]. Ideally, a previous rubber dam isolation should  be performed, eliminating the possibility of the patient to swallow or aspirate the pin, besides avoiding pulp contamination in case of perforation [19]. In case it is not possible, a piece of gauze is placed covering the tongue and most of the throat, and the pin hand wrenches is tied to a 30–35 cm piece of dental floss. Those precautions reduces the chances of the patient to swallow or aspirate the pin [18]. On the selected locations, before using the twist drill for channel preparation, an inden 

12

tation or starting point with 0.5 mm depth must be prepared, using a No. ½ or No. ¼ round bur (. Fig. 12.10c) [18]. This will avoid the drill used on the channel preparation to move around at the beginning of the procedure [7, 19]. This type of drill generally presents a stop to limit the adequate depth of the finished channel, being called depth-limiting drill. On this case, the wall which will receive the channel must be flat and form a right angle in relation to the direction of the drill insertion. The two cutting blades of the drill tip are sloped so that they will cut only when the drill is turning in a clockwise direction [19]. It has flutes with spiral patterns to remove the dentin chips from the channel (. Fig. 12.10d) [2]. It is important to preserve a space between the pin and the axial walls of the preparation, because this can hinder the bur to reach the adequate depth and also adversely affect the correct condensation of the amalgam between the pin and the axial wall [18, 19]. If necessary, the axial wall can be slightly cut to create space [19]. There must be a minimum of 0.5  mm of space around the pin to allow the condensation of the amalgam on its entire surrounding surface. The drill will enter and withdraw from the channel spinning continuously. If it stops inside the channel and a lateral load is applied, it may break. The channel must be prepared parallel to the nearest external surface of the tooth, avoiding to be directed to the periodontal ligament, causing a constant inflammation and bone resorption, or toward the pulpal chamber, causing pulpal exposure [7, 18]. The dentist needs to be sure that the bur is correctly positioned, with its long axis parallel to the external surface of the tooth. The technique for the correct placement of the bur is the same as the one previously described for the preparation of the channel for amalgapin (. Fig. 12.5c–g). During the channel preparation, it is advisable to withdraw the drill from the channel at least once, halfway the total extension of the head, to allow the dentinal cuttings to be cleared from the flutes of the drill, for a better efficient preparation and less heat production [19]. Then it is penetrated again until it reaches the stop and is completely removed. That means the channel is finished with only two consecutive penetrations. Care must be taken to avoid the over-enlargement of the channel, with multiple entries and withdrawals, due to the unavoidable small leaning of the bur by the dentist hands [18]. Then, the pin is threaded with a small pin wrench or a latch-type contra-angle low-speed handpiece [18, 19]. Some self-shearing pins have a weak point between it and the chuck in which they are attached. When they completely seat at the end of the channel, they break at this area, disengaging from shank and remaining in position (. Fig. 12.10g, arrow). The standard pins do not have this weak point and will require the use of a wrench (. Fig. 12.8b, 1 and 2). This type allows the dentist to feel the insertion by tactile sense, and after fully seated, which can be reverted one quarter turn, reducing the stress on the dentin created at the apical end of the channel [7, 18, 19]. Those pins also have the advantage to unscrew in case it is required. In case the standard pin is still hand-­ threaded after reaching the bottom of the channel, it may break or strip the threads in the dentin [18].  

 

 

 

 

..      Fig. 12.9  Locations for the pin insertion on upper premolar, upper molar and lower molar (green, preferred locations; yellow, caution location; red, locations with higher risk of perforation)

423 Extensive Amalgam Restorations

The fastest method to insert a pin is through the use of a contra-angle, simplifying the procedure. In situations of difficult access, even the pins intended for being threaded with a contra-angle may also be hand-threaded using a proper wrench that comes with the set (. Fig. 12.8b). Preferably, the gear reduction contra-angle handpiece (10:1) should be used, which increases the tactile sense of the operator and reduces the risk of stripping the threads [18]. To reduce the stress production when the pin tip reaches the bottom of the channel, some manufacturers produced pins with a shoulder stop [19].  

After the pin insertion, besides the pin tip penetrating 1.5–2 mm inside the dentin, the other side remains in preparation. A space of 2mm should be left between the top of the pin and the surface of the restoration, so that it can be covered with the restorative material and the final restoration can be resistant enough [7, 18, 19]. If the pin is too long and must be shortened, it can be cut with a cylinder or conical bur, placed perpendicular to the pin, avoiding it to be unscrewed with the rotation of the bur. To avoid heating, this must be performed with a proper airstream cooling [18]. If

a

b

c

d

e

f

..      Fig. 12.10  Technique for the use of the intradentinal pins. a Caries lesions with loss of the distolingual cusp and cavitation under the mesial marginal ridge; b tooth preparation and filling with GIC; c marking the channel location with the No. ¼ round bur; d helicoidal

drills with different diameters; e, f preparation of the channel; g, h pin being threaded (arrow – self-shearing weak area); i, j, k pin being bended; l pin in position

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g

h

i

j

k

l

12

..      Fig. 12.10 (continued)

the bur cannot be positioned perpendicular to the pin, it must be stabilized with a hemostatic forceps or cotton tweezer without using a lever, avoiding it to unscrew the pin from the dentin [19]. The preparation and the pin must be inspected, predicting the final contour of the restoration, analyzing if the pin will not touch or be too close to the matrix band, adversely affecting the condensation, and leaving little restorative material covering the pin. At least there must remain 1 mm of amalgam around the pin, between it and the external surface of the restoration. If necessary, it can be bended.

Amalgam condensers and dentin spoons should not be used to bend the pin, because the fulcrum of rotation would be at the entrance of the channel, which could cause cracks or fractures on the dentin, besides producing an abrupt bend that increases the fracture risk of the pin [2, 18]. To perform that, a fork-shaped bending tool must be used, which is connected to the pin and rotated until the desired bending is obtained (. Fig.  12.10i–k). This tool places the fulcrum of rotation in another location of the exposed pin, increasing the control of the pressure applied. If the amalgam restoration will be eventually used as a core, the pins must be folded  

425 Extensive Amalgam Restorations

correctly toward the center of the tooth, in a way they are not exposed during the axial reduction during the full crown preparation. If a drill or a pin fractures, its removal is difficult, if not impossible, and usually should not be attempted. The best solution for this problem is prevention. An alternative position for another pin must be chosen and the new pin inserted [2, 18]. If the channel is too wide and the pin cannot be threaded, a drill and the pin with a larger diameter are used. However, if this does not work, another option is to perform the cementation of the pin, retaining it by cement [19]. The penetration of the drill into the pulpal chamber is noticed by bleeding through the pin channel, besides feeling of sudden loss of bur resistance to hand pressure. The perforation can be also noticed when the pin goes further than the depth of the channel when being threaded. The penetration can also be noticed on radiography. However, the overlapping of the images of the pin over the pulp chamber may ­happen, resulting on a false idea of penetration. If the pulp penetration happens, the pin must be removed and the bleeding controlled, washing the preparation with saline solution or a calcium hydroxide solution and then drying with a small sterile cotton ball. Then, the pure calcium hydroxide powder is applied inside the channel, which must be covered with calcium hydroxide cement, as is performed with any accidental pulpal exposure during tooth preparation [18]. A perforation of the external tooth surface, until the periodontal tissue, may be suspected when the patient experiences symptoms during the preparation of the channel on a non-vital tooth. The perforation may be above or below the gingival margin. On the first case, the excess of the pin must be cut off, or it may be removed and the region restored with amalgam [19]. If it happened below the gingival margin, trans-surgical restorations, gingivectomy, or a surgery of crown lengthening may be required. Despite the type of problem that may have occurred, the patient must be informed of the proposed treatment. When the tooth to be restored lost both adjacent cusps, such as the loss of both supporting cusps preserving the

a

12

balancing cusps or both balancing cusps preserving the supporting cusps, the use of one pin per cusp will not produce a satisfactory result, due to the lack of distribution of resistance and resistance features. During mastication, there will be nothing to attach the remaining cusps to the restoration. Therefore, an oblique load over the restored cusps will produce the rotation of the restoration, causing fracture on the remaining tooth structure on the region where the pins were inserted. On those cases, horizontal pins inserted on the remaining cusps will reduce the likelihood of fracture (. Fig. 12.11a, b) [18, 19]. In case it is not possible due to the fragility of the remaining cusps, complementary vertical pins may be an option on the gingival walls, corresponding to the region of the marginal ridges, as closest as possible to the remaining cusps, considering that there is enough dentin between the gingival wall and the furcation [19]. In a comparative analysis between the use of slots and the amalgapin channels with the intradentinal pins, the first ones are easier and faster to be performed, do not induce stress on the dentin, and do not reduce the resistance of the restoration. In addition, they do not present any cost and may be indicated to teeth with short clinical crown or small cuspal-­ capping [18]. Some studies suggest that they are as retentive as the intradentinal pins [1, 17–19]. As a disadvantage, the natural retentions made directly with the amalgam require a greater removal of the tooth structure and a more critical restorative technique, especially at the moment of the matrix removal [7, 18].  

12.4.2.2 Endodontic Posts

If the pulpal chamber height is smaller than 2 mm, only the condensation of the restorative material on its interior is not enough to give the necessary retention for the amalgam restoration. To obtain additional retention in cases of severely destroyed and pulpless teeth, metallic posts can be used, which are cemented into the roots after its preparations. The amalgam is condensed over the posts, which create retention for the restoration (. Fig. 12.12).  

b

..      Fig. 12.11  Options to avoid the restoration rotation. a Additional orizontal pins; b multiple vertical pins

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without damaging the condensed amalgam [18]. The excess must be removed with a dry applicator but never with airstream. This way, the amalgam particles will mechanically interlock on the uncured adhesive layer while it is still fluid, which after the polymerization will produce the retention. If a light-cure adhesive is chosen, it must be applied according to the manufacturer’s recommendations and light-­ cured. Then, a thin layer of dual-cure resinous cement is applied. Before its self-curing, the amalgam must be fastly condensed, promoting an interlock of the amalgam with the resinous cement. In . Fig. 12.13a–i, an example of the bonded amalgam technique is presented. The bonding strength obtained may depend on the type of amalgam used. The spherical amalgam results in higher bond strength than the admixed or lathe cut. Some studies have shown that some adhesives are very effective, resulting on initial bonding strength values of 10–14  MPa [5, 16]. However, the characteristics of primary retention form related to the preparation shape are still recommended when an adhesive system is used, because it is not clear if the initial adhesion may be kept on adequate levels with the years. The bonded amalgam technique may reduce the marginal micro..      Fig. 12.12  Use of endodontic posts leakage and the postoperative sensitivity and improve the fracture resistance of the remaining tooth structure [14, 21]. 12.5 Bonded Amalgam Restorations The fracture resistance of the teeth with MOD-bonded amalgam restorations is two times higher than the regular ones The dental adhesives may be associated to amalgam restora- [4]. However, the obtained retention is not high enough and tions just with the aim to seal the dentin tubules and promote cannot replace the conventional retention and resistance the pulpal protection; or with the aim of bonding the amal- forms [3, 18]. According to Sturdevant [18], the use of adhegam to the tooth structure. If after the tooth preparation an sion, besides to increase the costs, the time spent, and the adhesive system is applied on the preparation and light-­ complexity of the procedure, has not been proved beneficial cured, and the amalgam is condensed afterward, it will not on the clinical studies throughout time, so it is not defended bond to the tooth structure. The adhesive layer  will be as a routine procedure. already polymerized/hard and will only act as a pulpal protection. On this case, the adhesive can be applied before the 12.6 Restoration of Extensive Preparations placement of the matrix band [18]. To promote the adhesion of the amalgam to the tooth structure, there are two possibilities. The first one is to use a When using a universal matrix retainer in cases of loss of dual-cure adhesive system, while the second one is to associ- three or more cusps, a gap of the matrix band at the region of ate a light-cure adhesive system to a dual-cure resinous the U-shaped guide posts will face the preparation, allowing cement. Even though the bonding mechanism between the the penetration of amalgam and impairing the restoration. adhesive and amalgam is not completely understood, it may To obtain a proper contact of the band around the entire be due to a micromechanical interlocking of the non-cured preparation contour, a small complementary matrix strip can adhesive with the non-crystallized amalgam during conden- be applied on the region of the gap as it can be observed in . Fig. 12.14a, b [7]. sation. On the other hand, on most large preparations, when it is First, the rubber dam isolation and then the matrix band and wedges are applied to the tooth. However, some kind of necessary to restore a lost cusp, the use of a universal matrix isolating coat must be applied to the band; otherwise the does not allow the desired contour (. Fig. 12.15b). Due to adhesive will bond to it and to the amalgam. In that case, dur- the need to stabilize the band screwing the spindle of the ing the matrix removal a portion of the amalgam will be matrix retainer, reducing the band diameter, it tends to pulled out from the restoration, since the material has not yet deform on the region of the lost cusp and penetrate into the reached the final strength. For that, casting wax or wax pen- preparation. To solve this problem, the operator can use rivcils can be used to isolate the matrix, rubbing the wax over eted (. Fig. 12.15a–o), spot-welded (. Fig. 8.33), or T-band the band [18]. If a dual-cure adhesive system is selected, it (. Fig. 8.34) custom-made matrices or even retainer less must be applied, and, before its chemical curing, the amal- circumferential matrices, with aluminum built-in tensiongam must be fastly condensed [18]. Little adhesive must be ing ring (TDV) or AutoMatrix (Dentsply) (. Figs. 8.4a–d applied to reduce its overflow, since it is difficult to remove and 8.5a, b).  

12

 

 

 

 

 

 

427 Extensive Amalgam Restorations

Tip

On large preparations with one or more lost cusps, the use of a universal matrix may not allow the desired contour. In those cases, riveted, spot-welded, or T-band custom-made matrices or even retainer less circumferential matrices with aluminum built-in tensioning ring (TDV) or AutoMatrix (Dentsply) are more indicated.

To prepare a riveted matrix (. Fig.  12.15a–o), using a stainless steel matrix band with a width slightly higher than the tooth to be restored, the operator measures the diameter of the tooth and cuts the band with 1 cm of excess, so it can be held tightly. In general, it is necessary about 5 cm of the matrix band [11]. The band is placed and adjusted around the tooth, and the dentist folds it with a flat nose plier or a curved-end mosquito forceps, creating the correct diameter (. Fig. 12.15a–d). The band is removed from the tooth, and  

 

a

b

c

d

e

f

..      Fig. 12.13  Restoration technique with bonded amalgam. a Large caries lesion which led to the complete undermining of the distolingual cusp; b preparation finished; c pulpal protection with the calcium hydroxide cement; d the GIC artificial dentin was applied under the mesiolingual cusp and riveted matrix surrounded by low fusing

compound wall was placed; e acid-etching; f dual-cure adhesive system application; g amalgam condensation over the uncured adhesive; h initial result; i restoration after the polishing

12

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g

h

i

12 ..      Fig. 12.13 (continued)

a

b

..      Fig. 12.14  a, b Use of the complementary strip in preparation with the loss of several cusps, on the region of the gap of the matrix retainer

the place marked with the fold is riveted one or two times with a riveting plier No. 141. The initial perforation is made, and then the band is inverted, repeating the procedure and creating the rivets (. Fig. 12.15e–i). If the dentist has a spot-­ welding device available, instead of riveting, the band can be welded in an adequate diameter (. Fig. 8.33). After that the  

 

matrix is placed in position on the tooth, and the operator evaluates its adaptation and folds the ends of the band over the external surface of the tooth (. Fig. 12.15j). The matrix is removed from the tooth and burnished on a paper mixing pad, to create an adequate contour for the proximal surface of the restoration (. Fig. 12.15k).  

 

429 Extensive Amalgam Restorations

After that, the matrix is taken in position, and wooden wedges are inserted on the mesial and distal interproximal spaces, using a mosquito forceps with a curved end. It is important to evaluate if the matrix is touching the adjacent tooth, in a way to allow the correct restoration of the contact point. The matrix is burnishing toward the adjacent tooth using the back of a dentin spoon or a Hollenback No. 6 burnisher (. Fig. 12.15l). Special attention must be kept to the contour of the matrix on the region of the axial angles. If nec 

essary, this area must be burnished until it reaches the correct contour. The matrix and wedge system can be additionally stabilized using heated low fusing compound, which is compressed over the buccal and lingual embrasure, taking care for the compound to not enter the tooth preparation (. Fig. 12.15m, n). Besides to help on the stabilization of the matrix, the compound hinders the overflow of the amalgam on the buccal and lingual surfaces or the proximal surface  

a

b

c

d

e

f

..      Fig. 12.15  Riveted custom-made matrix. a Preparation finished; b universal matrix applied resulted in deformation on the region of the distolingual cusps; c, d adjusting the matrix diameter; e–h riveting

procedure; i finished rivet; j bending the matrix end; k burnishing the contact point area; l burnishing toward the adjacent tooth; m, n stabilization with compound; o restoration concluded

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g

h

i

12

j

k

l

m

n

..      Fig. 12.15 (continued)

431 Extensive Amalgam Restorations

o

..      Fig. 12.15 (continued)

when there is no adjacent tooth [19]. The compound adhesion characteristics are useful because it bonds to the matrix and tooth at a low temperature, which will not cause damage to the soft tissues and teeth. When handled according to the correct technique, the use of low fusing compound is simple, easing significantly the restorative procedure (. Fig.  12.16a–i). Its correct use just requires some training. For that, approximately 2.5 cm of the tip of a compound rod is positioned over the flame of an alcohol lamp. The rod is moved forward and backward while it is turned between the fingers. After 5–10 s it is removed from the contact with the flame so that the heat may diffuse into the center. It is noticed that the rod end begins to bend, indicating that it is soft (. Fig.  12.16b). The softened compound is shortly immersed in a vial with water, preferably warm, to create a non-sticky surface. The operator wets the fingers and holds a small portion of softened non-sticky compound, preparing a small sphere (. Fig.  12.16c). He keeps the compound between his thumb, index, and middle finger of one hand and passes it quickly over the flame, creating a sticky surface (. Fig.  12.16f, g). Then, he bonds this surface to the index finger of the other hand and passes the compound quickly over the flame, making this surface sticky again (. Fig. 12.16h, i). The compound is then immediately applied over the matrix and the wedge (. Fig.  12.15m, n). The cold air of a syringe is directed over the compound to speed the solidification and stabilize the set. If excess of compound  overflows over the matrix or inside the preparation, it can be easily removed with cutting instruments. The compound must  

 

 

 

 

 

never be heated on the flame and directly applied over the tooth. This may cause damage to the pulp due to the prolonged application of heat [6]. If the matrix is slightly displaced from the contact or ideal contour due to the compound application, the back of a heated dentin spoon may be used, burnishing the matrix toward the adjacent tooth, softening the godiva, and readapting the contour of the matrix. If the compound is applied both at the buccal and lingual sides and it is necessary to stabilize the set, a staple can be prepared using an orthodontic wire or paper clip giving it a U shape. It is then heated and inserted in the compound, connecting both sides. The compound may be removed with a Hollenback carving and the staple with a heated tweezer. The heat will diffuse through the metal and melt the compound, allowing its removal [19]. For large restorations, it must preferably choose the amalgam of extended setting time, giving more time for carving and adjusting of the restoration. Also, for increasing the working time for carving due to the large preparation size, the amalgam may be taken into the preparation in large amounts. For that, instead of using the amalgam carrier, the portion of the triturated amalgam may be divided into two parts and taken into the cavity with a tweezer [19]. The condensation must start in the prepared natural or artificial retentions [18]. The carving of the occlusal area must be fast, even if coarse, allowing the prompt matrix removal and carving of the more difficult areas, such as the gingival and interproximal margins, removing any excess. Conclusion This chapter describes the technique for extensive amalgam restorations. The details of tooth preparations for improving the retention and resistance were presented. The technique of cuspal-coverage of weakened cusps can avoid aggressive fractures of the remaining cusps, preserving the tooth structure. The different preparation techniques of natural (vertical walls, axial offset, locks, coves, dentin pins, slots, amalgapin, and pulpal chamber retention) and artificial retentions (intradentinal pins and endodontic posts) can prevent the restoration dislodging due to interarch teeth contact and chewing forces. The association of adhesive systems with amalgam can also be an alternative to improve the resistance of the remaining structure, besides helping its retention. The amalgam can be an effective and a low-cost alternative of severely damaged teeth, being an important part of the practitioner’s dental knowledge.

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a

b

c

d

e

f

12

..      Fig. 12.16  Technique of low fusing compound handling. a, b Softening of the compound over the flame; c, d superficial cooling of the compound and wetting of the finger; e, f removal of a portion and

preparation of a small ball; g superficial heating of the ball recovering its bonding capacity; h sticking the ball at the tip of the finger; i superficial heating of the small compound ball

433 Extensive Amalgam Restorations

g

h

i

..      Fig. 12.16 (continued)

References 1. Bailey JH.  Retention design for amalgam restorations: pins versus slots. J Prosthet Dent. 1991;65:71–4. https://doi.org/10.1016/00223913(91)90052-X. 2. Baum L, Phillips RW, Lund MR. Textbook of operative dentistry. 3rd ed. Philadelphia: Saunders; 1995. 3. Dias de Souza GM, Pereira GD, Dias CT, Paulillo LA.  Fracture resistance of teeth restored with the bonded amalgam technique. Oper Dent. 2001;26:511–5. 4. Eakle WS, Staninec M, Lacy AM. Effect of bonded amalgam on the fracture resistance of teeth. J Prosthet Dent. 1992;68:257–60. https://doi.org/10.1016/0022-3913(92)90325-5. 5. Eakle WS, Staninec M, Yip RL, Chavez MA.  Mechanical retention versus bonding of amalgam and gallium alloy restorations. J ­ ­Prosthet  Dent. 1994;72:351–4. https://doi.org/10.1016/0022­3913(94)90552-5. 6. Gilmore HW, Lund MR.  Operative dentistry. Saint Louis: Mosby; 1973. 7. Horsted-Bindslev P, Mjör IA.  Dentística operatória moderna. São Paulo: Santos; 1990. 8. How WS.  Bright metal screw posts and copper amalgam. Dent Cosm. 1889;31:237. 9. Howard WW. Atlas of Operative Dentistry. 2nd ed. St. Louis: Mosby; 1973. 10. Markley MR.  Restorations of silver amalgam. J Am Dent Assoc. 1951;43:133–46. https://doi.org/10.14219/JADA.ARCHIVE.1951.0192.

11. Mondelli J, Ishikiriama A, Galan JJ, Navarro MF.  Dentística Operatória. São Paulo: Sarvier; 1976. 12. Mondelli RF, Barbosa WF, Mondelli J, Franco EB, Carvalho RM. Fracture strength of weakened human premolars restored with amalgam with and without cusp coverage. Am J Dent. 1998;11: 181–4. 13. Mooney B. Operatoria dental. Buenos Aires: Panamericana; 1995. 14. Neto NG, Carvalho RC, Russo EM, Sobral MA, Luz MA. Dentística Restauradora: Restaurações diretas. São Paulo: Santos; 2003. 15. Outhwaite WC, Garman TA, Pashley DH.  Pin vs. slot retention in extensive amalgam restorations. J Prosthet Dent. 1979;41:396–400. https://doi.org/10.1016/0022-3913(79)90036-2. 16. Perdigão J, Lopes M. Dentin bonding--questions for the new millennium. J Adhes Dent. 1999;1:191–209. 17. Plasmans PJ, Kusters ST, de Jonge BA, van’t Hof MA, Vrijhoef MM. In vitro resistance of extensive amalgam restorations using various retention methods. J Prosthet Dent. 1987;57:16–20. https://doi. org/10.1016/0022-3913(87)90108-9. 18. Roberson TM, Heymann H, Swift EJ. Sturdevant’s art and science of operative dentistry. 5th ed. St. Louis: Mosby; 2006. 19. Schwartz RS, Summitt JB, Robbins JW.  Fundamentals of operative dentistry. A contemporary approach. Chicago: Quintessence; 1996. 20. Shavell HM. The amalgapin technique for complex amalgam restorations. J Calif Dent Assoc. 1980;8:48–55. 21. Torii Y, Staninec M, Kawakami M, Imazato S, Torii M, Tsuchitani Y.  Inhibition in  vitro of caries around amalgam restorations by bonding amalgam to tooth structure. Oper Dent. 1989;14:142–8.

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Light-Curing Units Nicola Scotti, Andrea Baldi, Edoardo Alberto Vergano, Claudio Hideki Kubo, and Carlos Rocha Gomes Torres 13.1

Introduction – 436

13.2

Fundamentals of Light – 436

13.3

Curing of Composite Resins – 436

13.3.1 13.3.2 13.3.3 13.3.4

 ctivation Systems of Curing Reactions – 437 A Chemically Activated Materials – 437 Light-Activated Materials – 437 Polymerization Kinetics – 438

13.4

Polymerization Shrinkage – 438

13.4.1 13.4.2 13.4.3 13.4.4 13.4.5

T he Material, in Terms of Volumetric Shrinkage and Elastic Modulus – 439 The Geometrical Configuration of the Preparation or “C-Factor” – 439 The Speed of Curing and Shrinkage Direction – 440 The Substrate and Its Elastic Modulus – 441 The Layering Technique Employed – 441

13.5

Oxygen-Inhibited Layer – 441

13.6

Thermal Effects of Polymerization on Pulp – 441

13.7

Light-Curing Units – 442

13.7.1 13.7.2 13.7.3 13.7.4

 uartz-Tungsten-Halogen Unit – 442 Q Plasma Arch Unit – 445 Argon-Ion Laser Unit – 447 Light-Emitting Diode Unit – 448

13.8

Monitoring of the Light Output – 449

13.9

Curing Protocols – 453

13.9.1 13.9.2

 onventional Protocol – 453 C Gradual Curing Protocols – 456

13.10 Polymerization of Indirect Restorations – 457 13.11 Fiber Post Cementation – 458 13.12 Ocular Hazards of Curing Lights – 460 References – 461 © Springer Nature Switzerland AG 2020 C. R. G. Torres (ed.), Modern Operative Dentistry, Textbooks in Contemporary Dentistry, https://doi.org/10.1007/978-3-030-31772-0_13

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Learning Objectives The reader will be given the opportunity to understand and learn: 55 Fundamentals of light and polymerization in dentistry 55 Shrinkage stress: the problem and its management 55 Effects on dental pulp 55 Light-curing units and their maintenance 55 Clinical protocols in different situations 55 Ocular hazard and its management

13.1  Introduction

13

On the 1970’s decade, the use of light to promote the curing of a restorative material began to be used, pushing the developments of several light-activated materials and the light-­ curing units. Those began to be used on several dental specialties, turning the use of the light something almost indispensable for many clinical procedures. Therefore, the understanding of the concepts about the light activation process, the physical properties of the light and chemical process of curing, as well the basic understanding of the light-curing devices became an essential knowledge for the dentist. However, a study showed that more than 37% of the composite restorations are unsatisfactorily light cured [28] showing that the theoretical knowledge and the quality of the dentist’s work, when the light curing is involved, are far from the necessary. Thus, a correct curing protocol is fundamental in order to achieve good mechanical and aesthetical proprieties with resin composite [66]. Although many different articles are talking about this topic, a recent review showed that there is not really accordance between the studies about the best protocol available [114]. 13.2  Fundamentals of Light

Light is electromagnetic radiation, i.e., energy in movement that propagates through waves, and it is capable to cause a visual sensation on an observer. This light wave behavior is explained by the theory of electrodynamics. Depending on the wavelength (distance between two successive peaks of a wave), the light radiation will have distinct characteristics and effects when interacting with the matter.

Light is electromagnetic radiation, i.e., energy in movement that propagates through waves, and it is capable to cause a visual sensation on an observer.

. Figure 13.1 shows the electromagnetic spectrum, on which the waves vary according to the wavelength. The shorter it is, the more energy the wave has, and more deeply is capable to penetrate on the matter that receives the radiation. Gamma and X-rays, examples of high energy waves, are capable to  

Radio 102 104 Microwaves Invisible thermal waves

770 nm

10–1 Red Infrared 10–2

Visible light Visible

Orange

10–5 Ultraviolet 10–6

Invisible ionizing waves

Yellow

620 nm 592 nm 575 nm

Green 500 nm Blue

X-rays

Indigo

10–8

Violet

464 nm 466 nm 390 nm

Gamma rays 10–10 10–12

..      Fig. 13.1  Electromagnetic spectrum

cause the ionization of the molecules. Ultraviolet (UV) waves are slightly longer and have the potential to cause damage on the cell DNA and produce skin cancer. Above the ultraviolet wavelength, there is the visible light, which is on an interval between 390 and 770 nm, and is capable to stimulate the photoreceptor cells in the eyes and be perceived by the human beings. The variation of the wavelength in this interval determines its color. The white light is a mixture of several wavelengths. The waves with a slightly longer wavelength than the visible light correspond to the infrared, which is capable to promote the heating of the matter it interacts and are known as thermal waves. 13.3  Curing of Composite Resins

The composite resins are basically composed of some main ingredients, which are methacrylate monomers (organic matrix); filler particles (inorganic matrix); coupling agent (organosilane) that bond the organic matrix to the filler particles; activator-initiator system of the polymerization reaction; inhibitors to prevent the spontaneous polymerization of monomers; and optical modifiers to give coloration and opacity to the material. The polymerization process consists of the conversion of monomers to polymers, initiated by the formation of a free radical with an unpaired electron, which reacts with one of the electrons of the unsaturated group (double bond) in the monomer molecule, leaving the other electron in an unsaturated state. Thus, this monomer becomes to act as a free radical bonding to another monomer, which also becomes a free radical, adding successively to a large number of mole-

437 Light-Curing Units

cules so that the polymerization process continues through the propagation of the reactive center.

because only a limited contour may be performed before the curing is complete [88].

13.3.1  Activation Systems of Curing

13.3.3  Light-Activated Materials

Reactions

The monomers polymerization may occur by two mechanisms, called condensation and addition. On the condensation reaction, during the polymer formation, a by-product is created, which in generally lost to the environment by volatilization. However, in the addition reaction, all monomers will be part of the polymeric chain, and no by-product is formed. The restorative composites polymerize by an addition reaction. Even though condensation process is faster and less expensive in terms of material used, the reaction incorporates disadvantages related to the presence of the by-product. The loss of reaction product could create voids in the chemical structure of the polymer, leading to weaker zones and a more evident shrinkage during the reaction. On the other hand, addition-based reactions are more difficult to take place as they require the presence of a catalyst and initiator. Polymers obtained with such a process however are more stable and precise. The free radicals may be generated in four different ways: 1. Chemically, by the interaction between the initiator and activator substances on a two-paste material when it is mixed 2. By specific light wavelengths 3. By heating 4. By a combination of activation systems (light + chemical reagents) [3]

On the light-activated composites, the curing process starts by the absorptions of the visible light on a specific wavelength. The first light-activated composites used the ultraviolet light, with wavelength from 320 to 365  nm. They revolutionized the market and gained immediate acceptance due to its inherent advantages. However, the harm caused by the ultraviolet on the eyes and the limited depth of cure led to its replacement by the visible light systems [16]. Most of the current materials  have as a photoinitiator α-diketone molecules, generally camphorquinone, which is excited by the light and interacts with a reducing agent, known as the activator, to produce free radicals, which start the curing process. The activator is a tertiary amine, and its concentration on the light-activated composites is much smaller than the one used on the chemically activated materials, which significantly decreases the possibility of staining or discoloration [87, 104]. The  light absorption range of the camphorquinone is in between 450 and 490 nm, that is, in blue region of the visible light spectrum, with a maximum peak on 468  nm [17, 70]. The camphorquinone presents, as its main disadvantage, a yellow color, which adversely affects the production of composites with lighter  colors [103]. After curing it becomes whiter, resulting in a color difference between the material before and after polymerization (. Fig. 14.21). The decomposition of the photoinitiators may result in the material darkening with time, when exposed to the environmental light, causing esthetic problems (. Fig.  13.2). In attempt to solve this problem, other photoinitiators were developed and tested, such as the Ivocerin and PPD (phenyl-propanedione). The latter has a maximum absorption peak close to 390 nm and does not have the characteristic yellow color of camphorquinone. However, not all light-curing units emit a light spectrum capa 

 

13.3.2  Chemically Activated Materials

The chemically activated restorative materials, also known as self-cure composites, are supplied as two-paste systems either in jars or syringes (base and catalyst), which are mixed before the use. The free radicals are generated by the chemical reaction between the benzoyl peroxide (initiator) on the catalyst paste with the tertiary amine (activator) on the base paste, which will begin the curing of the methacrylate groups [3, 16]. The degradation of residual amines in the composition on those materials contribute for the discoloration observed after 3–5 years of intraoral service. The selfcured composites have mainly aromatic tertiary amines, while the light-cured ones generally have aliphatic amines. Therefore, light-cured composites are expected to have more color stability, since the amines in the composition are less susceptible to oxidation. On the self-cured composite, the need to mix pastes results in the formation of internal air bubbles, that can contribute to the creation of internal porosity and therefore an early staining. Furthermore, the working time is limited due to the speed of the curing process, taking more time to finish and polish the restoration,

..      Fig. 13.2  Color alteration of light-cured composite restorations due to changes of reacted camphorquinone by the exposure to the environmental light

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Absorbance (AU)

Camphorquinone Phenyl-propanedione Lucirin TPO

400

420

440 460 480 Wavelength (nm)

500

520

..      Fig. 13.3  Spectral absorption profiles of the camphorquinone, phenyl-propanedione, and Lucirin TPO photoinitiator

ble to stimulate it, because its absorption range  is different from the camphorquinone [91, 101]. Other photoinitiator used as an alternative for camphorquinone is the Lucirin TPO, which is becoming more popular by the fact it turns completely clear when the activation reaction ends. . Figure 13.3 shows the spectral absorption profiles of the most used photoinitiators. The light-activated materials have a longer working time, which results in less need of finishing the restoration. They have more color stability and less internal porosity [88].  

than this point, the polymerization shrinkage creates stress on the polymer chain, and the reduced mobility of the chains hinders the stress to be accommodated internally by the resin. This stress is transmitted to the tooth-restoration interface and tooth structure and may promote the breaking of the adhesive bond, cuspal deflection, or enamel microcracks [87, 88, 112]. This stage is known as the post-gel phase. The growing conversion until its final level at the glassy stage increases the elastic modulus. Therefore, the degree of conversion has a substantial effect on finally obtained mechanical properties. 13.4  Polymerization Shrinkage

During the polymerization reaction, the intermolecular distance is reduced due to the formation of covalent bonds, thus reducing the final volume [3, 42]. According to a recent review, the shrinkage range is quite variable, and the final volumetric contraction could reach 7%, with an average of 2–3% [55]. Moreover, during the first 24 h after the light curing, this polymerization reaction continues, as well the shrinkage, developing forces within the preparation walls that could led to microcracks or interfacial opening, during the first hours of clinical function [108]. This phenomenon is usually named post-polymerization, post-cure polymerization, or dark polymerization and is shown in . Fig. 13.4 [78]. Following the vitrification of the material (post-gel phase), all the free radicals and molecules containing double bonds that have not reacted remain entrapped in the matrix, without the ability to flow. Moreover, it has been observed that, owing to photoactivation, once the composite material has reached its vitreous form, some “free spaces” remain. After the exothermic polymerization reaction, the composite temperature is reduced to that of the oral cavity. A relaxation  

During the curing reaction, the composite resins transform from a plastic viscous material through a rubbery viscoelastic into an elastic glassy stage, passing through three phases identified as pre-gel, gel point, and post-gel phase [21]. >> During the curing reaction, the composite resins transform from a plastic viscous material through a rubbery viscoelastic into an elastic glassy stage, passing through three phases identified as pre-gel, gel point, and post-gel phase.

At the beginning of the polymerization, only some monomers are chemically bonded, and the system is still mainly a viscous liquid. During the conversion of monomers to polymer, the formation of new monomer to monomer bonds causes shrinkage, reducing the total volume. At this phase, there is a predominance of linear polymer chains, which are not well connected to each other, and the material may flow and undergo molecular rearrangement. The system is in a flow state, creating little stress on the adhesive interface. This stage is known as the pre-gel phase. When the degree of conversion reaches 10–20%, the polymer chains are long enough to create a gel, and the molecular movement of the organic matrix is reduced by the formation of cross-linked bonds. The material stops to behave as a liquid, which may flow, and begins to behave as a solid, with physical and mechanical properties being modified [112]. This moment is known as the gel point. Further

Post-polymerization

0.6

Degree of polymerization

13

13.3.4  Polymerization Kinetics

0.5 0.4 0.3 0.2 0.1 0

0

0.5

1

1.5

2 2.5 Time [s]

3

3.5

4

4.5 ´ 104

..      Fig. 13.4  Increase on the degree of polymerization after the end of light-curing procedure, namely post-polymerization or dark polymerization

439 Light-Curing Units

process follows, which is necessary for the structure to reach a more stable crystalline form, and this is associated with a partial reduction of the “free spaces” present within the polymer network. This physical phenomenon is responsible for the spontaneous approach of free radicals to the residual double bonds. These may react, allowing the composite material to further increase the conversion degree [109]. The volumetric shrinkage during polymerization produces stress on the tooth/restoration bonded interface, and is transmitted to the remaining tooth structure. The shrinkage stress can be thought as a negative pressure applied on cavity walls. The shrinkage stress may lead to interfacial gap formation, because the vectors occur toward the center of its mass. As the restorative material has been bonded to one or more preparation walls, the stress generated will be affected by the restriction’s conditions imposed by the bonded walls of the preparation, and all the stress will be directed toward the bonded surfaces. In vitro studies have shown that a continuous increase of shrinkage stress occurs for different periods of time after the photoactivation process [73]. The increase of stress following light exposure is associated with the addition polymerization and with the occurrence of thermal shrinkage in the restorative composite [4, 32]. The volumetric shrinkage may cause stress levels of 4–8 MPa or even more on the tooth-restoration interface. This depends on several factors, as described in the following sentences. >> The internal stress created inside the composite during polymerization is described as “shrinkage stress.” It is transferred through the interface to the cavity walls, leading to interfacial gap formation and cuspal deflection.

13.4.1  The Material, in Terms of Volumetric

Shrinkage and Elastic Modulus

There are some very important factors which affect the total volumetric shrinkage of composite materials [87]. The first one is the organic matrix. It is composed of a monomers mixture which is converted from a group of free-floating molecules into a rigid cross-linked polymeric chain and is responsible for the volumetric shrinkage during the polymerization [3, 10]. Therefore, the larger the percentage of the organic matrix of a material, the larger is the polymerization shrinkage. Other important factor is the amount of filler particles in the formulation. The higher is the filler content of a composite, the smaller is its organic content and, therefore, its volumetric shrinkage. However, the increase of the filler content also influences the elastic modulus of the material [10]. Some studies analyzed the polymerization shrinkage of several composites and observed that the higher the filler ratio, the greater is the elastic modulus and the stiffer the composite is, producing a higher shrinkage stress [88, 95]. According to Hooke’s law, stress is a product of the stiffness of the material (elastic modulus) by a given strain (volumetric shrinkage).

Therefore, the shrinkage stress will be higher if the elastic modulus and/or the volumetric shrinkage are also high. However, the shrinkage stress of a composite is more related to the stiffness of the material, which is proportional to the content of inorganic fillers, than to the percentage of volumetric polymerization shrinkage [21, 42]. >> Some studies analyzed the polymerization shrinkage of several composites and observed that the higher the filler ratio, the greater is the elastic modulus and the stiffer the composite is, producing a higher shrinkage stress.

13.4.2  The Geometrical Configuration

of the Preparation or “C-Factor”

The cavity configuration factor or C-factor was proposed by Feilzer et  al. [31], in 1987, and is the ratio of the bonded surface area (B) in preparation for composite restoration to the unbonded (U) surface area, expressed by the eq. C-factor = B/U [31]. In . Fig.  13.5 are shown situations with different C-factor values. The situation when the C-factor is higher is on box-shaped preparation, with four surrounding walls and an internal wall, such as on Class I preparation. On this case, if the composite is applied in a bulk increment, it will bond simultaneously to five walls (buccal, lingual, mesial, distal, and pulpal), and only the occlusal surface will remain unbonded. Therefore, the C-factor will be equals five. On Class II simple proximal box preparation (vertical slot preparation), the buccal, lingual, axial, and gingival walls will be bonded, while the surfaces facing the occlusal and proximal areas will remain unbonded, resulting on a C-factor equals 2. The case with smaller C-factor occurs on restorations of fractured anterior teeth, with only one bonded surface and five unbonded ones, and a C-factor equals 0.2. In this case, the risk of adverse effects due to polymerization shrinkage will be very low [88]. Therefore, the C-factor varies according to the shape and location of the preparation.  

The cavity configuration factor or C-factor is the ratio of the bonded surface area in preparation for composite restoration to the unbonded surface area. It determines the magnitude of the generated stress on the tooth-restoration interface and may cause the rupture of the adhesive interface or the cusp deflection.

>> The situation when the C-factor is higher is on box-shaped preparation, with four surrounding walls and an internal wall, such as on Class I preparation. On this situation, if the composite is applied in a bulk increment, it will bond simultaneously to five walls, and only the occlusal surface will remain unbonded.

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a

0,2

0,5

1,0

2,0

5,0

b

1/5 = 0.2

3/3 = 1

4/2 = 2

5/1 = 5

..      Fig. 13.5  a Schematic drawing of the C-factor. (Adapted from Feilzer et al. [31]). b Pictures of actual cavities with different C-factor

13

Tip

The C-factor must be kept as lower as possible, which can be obtained by the application of oblique composite increments, connecting a maximum of two walls simultaneously, leaving the larger number of free surfaces as possible, and creating conditions to relieve the stress.

When a composite is bonded to more than one preparation wall, the remaining tooth structure to where it is bonded, because of being rigid, will withstand the movement of the shrinking material, producing stress. The unbonded surfaces will deform whatever possible to reduce the stress. Since the composite flow is more likely to occur from the free surfaces, a higher proportion of free composite surface would represent a smaller restriction to shrinkage, therefore reducing the stress. Therefore, the cavity configuration determines the magnitude of the generated stress on the tooth-restoration interface, which may cause the rupture of the adhesive interface or the cusp deflection [87]. The greater the C-factor, the greater the potential of rupture of the adhesive interface due to the polymerization effects. To avoid this inconvenient, the C-factor must be kept as lower as possible, preferably close to 0.5, which can be obtained by the application of oblique composite increments, connecting a maximum of two walls

simultaneously, leaving the larger amount of free surfaces as possible, and creating conditions to relieve the stress [7]. In addition, if the material is cured in small amounts, less shrinkage stress will occur. The volumetric shrinkage of an increment is compensated by the next layer applied. However, as the C-factor consists of the ratio of the bonded surface area to the unbonded free surface area, when comparing two Class I preparations, with five bonded and one free wall, with different depths but other dimensions the same, the deeper preparation will have a greater C-factor than the shallower one [87]. Despite the size of the preparation, each increment applied must be small, with a maximum thickness of 2 mm, as will be discussed later. 13.4.3  The Speed of Curing and Shrinkage

Direction

The unbonded composite presents isotropic shrinkage, which means that shrinkage vectors are directed to center of the mass [31]. On the 1980s, it was believed that only the chemically cured composites presented this property. In relation to the light-activated ones, it was supposed that the polymerization shrinkage was directed toward of the light source [62]. Due to this fact, Lutz et al. [62] described a technique for restorations of proximal preparations using clear and reflective wedges that they had developed, associated

441 Light-Curing Units

with clear matrix bands. The light was first applied on the buccal/lingual surface, over the wedge, which conducted the light toward the gingival region. The authors believed that the good results obtained with this technique, in relation to the marginal integrity of the restorations, were due to the use of reflective wedges, which directed the shrinkage, bringing the resin toward the gingival wall, reducing the marginal gaps. However, Lösche [61] demonstrated that the use of reflective wedges only reduced the transmitted light, delaying the gel point and thus improving the marginal adaptation. Versluis et al. [113], using the finite element method, demonstrated that the composites do not shrink toward the light source but toward the bonded walls, and the shrinkage vectors are mostly determined by the cavity configuration [60, 113] The chemically activated composites have slower curing reaction than the light-activated ones (more than 3 min). This gives the material a longer pre-gel phase, allowing more flowing of the linear polymer chains recently created, relieving the stress, and resulting in less failures on the ­tooth-­restoration interface [25, 52, 87]. On the lightactivated composites, shrinkage stress created on the tooth structure is greater than on the chemically activated ones, because the curing reaction happens faster. That significantly reduces the time for the polymer chains flowing during the pre-gel phase and the stress relieving [87]. A way to control the stress is changing the curing mode (gradual curing/soft start), creating a slower start with less light irradiation, in order to prolong the pre-gel phase. Those techniques will be better explained at the end of this chapter [8, 81]. Tip

On regions of hot weather, the composites are generally kept inside a refrigerator, at about 5 °C, to increase its shelf life. However, before the use, it must be left to reach the room temperature, once the low temperature adversely affects the curing reactions.

13.4.5  The Layering Technique Employed

Layering technique is a fundamental factor, which is closely related to the “C-factor.” It has been shown that horizontal layers create significantly higher stress than oblique layers, since the bonded/unbonded ratio is clearly different [23, 50]. The thickness of each layer should be maximum 2 mm, to reduce the total stress and allow a proper curing on the bottom of the composite layer [53, 55]. It has also been shown, in vitro with SEM and in vivo with sensitivity test, that bulk techniques have inferior performances than incremental ones [72]. 13.5  Oxygen-Inhibited Layer

Light-cured resins leave behind a soft and sticky superficial layer after polymerization. This layer is commonly referred to as an oxygen-inhibited layer (OIL) because of its origin, and it is always produced when a resin composite or dental adhesive is cured in contact with air [102]. Oxygen reacts with carbon-based polymerizing free radicals in a diffusion-­ controlled manner to form peroxy radicals. These peroxy radicals preferentially react with oxygen, which significantly retards the polymerization reaction [57]. They also quench the excited triplet states of photoinitiators, such as camphorquinone, thereby limiting the initiation stage of polymerization [54]. The OIL is primarily composed of unreacted resin monomers and oligomers, and it possesses a gel-like consistency. Previous studies have found that the OIL thickness of adhesives and resin composites ranges from 4 to 40 μm [35, 90, 98]. The thickness and characteristics of the OIL in resin-based materials depend on several factors, including monomer chemistry, filler morphology, radical concentration, and the rate of oxygen consumption. Therefore, the characteristics of OIL of dental adhesives might differ depending on the types of adhesive systems. A simple way to deal with OIL is to perform, once the last composite layer is completed and cured, an extra curing step after covering the restoration with a transparent glycerin layer (. Fig. 15.6z, a´). This procedure avoids the contact with oxygen and thus strongly reduces the OIL.  

13.4.4  The Substrate and Its Elastic Modulus

The substrate could also play a role in the shrinkage stress. More elastic substrates, such as dentin, could better tolerate a volumetric variation, while rigid substrates, such as enamel, don’t have this advantage. Following this reasoning, the use of a liner layer between the adhesive and the restorative composite, using a material with low elastic modulus such as flowable composites, has been proposed, but its real effectiveness is still controversial [53]. Dealing with natural tooth structure, we have to consider that adhesion to dentin is less effective than to enamel, which can result on interfacial debonding and gap formation, rather than a deformation of the substrate during polymerization.

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13.6  Thermal Effects of Polymerization

on Pulp

Curing times suggested by manufacturers are generally evaluated in  vitro under optimal conditions, which could be totally different from the real clinical condition, leading to an inadequate polymerization of the restoration [59]. This might lead to negative mechanical properties and lower biocompatibility of the composite material. The simplest way a practitioner can overcome this issue is by extending the curing time beyond manufacturer recommendations. This approach has been shown to improve the degree of conver-

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sion and microhardness at the bottom of the composite layer, while also reducing the amount of elutable species [27]. However, curing with high emittance units for extended time raises concerns regarding possible overheating of the dental pulp [76]. The in vivo effects of pulp heating and its biological consequences were studied since 1965 by Zach and Cohen [120]. In their study, a 5.5 °C pulp temperature variation was simulated in rhesus monkeys, through application of a hot metal source to the facial enamel surface. This led to necrosis in 15% of evaluated pulps. After their study all in vitro and in vivo studies addressing the effects of LCU light on pulp temperature assumed 42.5 °C as a cutoff temperature. On the other hand, in contrast with previous in  vitro results, Schneider et al. reported that long exposure periods (60 seconds) were clinically necessary to cause a pulp temperature variation higher than 5.5 °C, when using a polymerization device on intact premolars (radiant emittance values of approximately 1200 mW/cm2) [96]. When blue light strikes the enamel surface, part of the light energy is reflected and a part is converted into thermal energy, while the remaining portion passes through the ­substrates below [22]. When blue light reaches the pulp tissue, photons are strongly absorbed by the blood chromophores to be partly converted into thermal energy [37], resulting in a slower pulp temperature increase in vivo than the one observed in vitro. Because of the constant blood flow, the warmed chromophores from absorbed photons are quickly replaced by other, cooler ones, so most of the heat generated in this tissue is dissipated. In general, most of the temperature rise occurred within 5–10 s after the start of light curing. Extending the curing time to 30 s resulted in a minor additional increase. However, a possible way to prevent overheating of the pulp seems to be the contextual use of an air blowing directly toward the tooth while performing photopolymerization. 13.7  Light-Curing Units

The light-curing unit is a device capable to emit visible blue light required to activate the photoinitiators and start the polymerization. The spectral power or output (radiant power per wavelength) may vary among the devices but must be as close as possible to the absorption range of the photoinitiator within the composite. They can be classified according to the type of emitted light and the range of the wavelength spectrum emission in two types, called narrow and broad spectrum. The first broad-spectrum units generate white light that, when passing through band-pass filters, emits blue in the 400–520 nm range [16]. As examples, there were the conventional devices with quartz-tungsten-halogen lamps and the xenon plasma arc curing lamps. As disadvantages, they produce heating and waste electric energy, but as advantage, they have the capacity to activate other photoinitiators besides camphorquinone [91].

The narrow-spectrum units emit light on a relatively narrow range such as the argon-ion lasers and light-emitting diodes [43]. Those devices emit light mainly on absorption range of the camphorquinone, the photoinitiator used by most of the composite manufacturers. However, when using narrow-spectrum devices, knowledge and attention from the operator are required to properly select the restorative materials, to avoid those which do not contain camphorquinone [87]. The general technical details of the different devices are presented next. 13.7.1  Quartz-Tungsten-Halogen Unit

The quartz-tungsten-halogen (QTH) light-curing units were the first visible light-curing devices created and were considered the standard curing units for several years. They have as basic components the light emission source (light bulb and reflector), UV and infrared band-pass filters, light guide, cooling fan, and a circuit board as it can be seen in . Fig. 13.6a–e [16].  

13.7.1.1  Light-Emitting Source

The light sources on the conventional devices are incandescent light bulbs. They have a quartz bulb, because this material is much more resistant to the heating than the regular glass, allowing smaller light bulbs to be manufactured. They have a tungsten filament, surrounded by a halogen gas on its interior to preserve the heated filament. They generally have a power between 50 and 100 watts, so they can emit light with the necessary radiant emittance [41]. Light is generated when the filament is heated and starts to glow due to the passage of the electrical current, which is called incandescence (. Fig.  13.7). It emits a great variety of wavelengths, especially infrared, as it can be observed in . Fig. 13.8. Only 0.5% of the emitted energy corresponds to the blue light, useful on the light-curing process, representing only 1% of the electric energy consumed, showing inefficient conversion of the elec 

 

b a

c

e d

..      Fig. 13.6  Internal components of a QTH light-curing unit. a Light guide; b shield for protection of the operator’s eyes; c band-pass filters; d QTH light bulb and reflector; e location of the cooling fan

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Radiantflux

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Camphorquinone Phenyl-propanedione Lucirin TPO

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440 460 480 Wavelength (nm)

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520

..      Fig. 13.9  Emission spectrum of a QTH light-curing unit (blue area) in relation to the spectral absorption profiles of the more commonly used photoinitiators (lines) ..      Fig. 13.7  QTH incandescent lamp attached to the reflector

Visible

Infrared

Radiant flux (µW/nm)

UV

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1000

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2000

2500

Wavelength (nm) ..      Fig. 13.8  Total emission spectrum of a QTH lamp (black line). The blue area corresponds to the emission spectrum of the light-curing unit after passing through the band-pass filters

tricity on light [87, 91, 107]. The emission spectrum of the QTH devices coincides with the absorption range of the most used photoinitiators, such as the camphorquinone and phenyl-­propanedione (. Fig. 13.9). The reflector is an element that comes attached to the light bulb, which reflects the light generated by the source toward the exit of the light (. Fig. 13.7). It has a parabolic shape, and it is covered by a highly reflective film, called dichroic. The dichroic reflectors allow the light with wavelengths longer than 700 nanometers to pass through, reflecting and selecting only the visible portion of the light, reducing the heat emission [87]. Due to the heating and cooling cycles that occurs during the use, there may happen condensation of vapors over its surface, dulling or clouding the reflector, and decreasing its ability to reflect light. It can be cleaned with alcohol and cotton swabs to renew the its reflexivity [88].  

The light output of a QTH bulb reduces during the use, and the speed of its degradation will depend on the time that it is used and the number of times it turns on or off during a given period of time [16]. Therefore, the light output must be frequently evaluated (3–6 months according to the manufacturer) with devices called radiometers. When there is a reduction in the output, the bulb replacement must be performed. The QTH bulbs are rated for a lifespan of 80–100 h, corresponding to about 2.5 years of clinical service, but may last three times more under ideal conditions [88]. There are three main causes for the bulb degradation, which may decrease the light output of the device, but that may not be noticed by visual inspection: 1. Blackening of the bulb that covers the tungsten filament due to the breaking of the halogen cycle, promoting the reduction of the light output up to 70% [16]. 2. Bulb opacification or “frosting” is characterized by the white opaque color of the bulb due to devitrification. It happens because of the crystallization of impurities of the bulb glass, which blocks the passage of light generated by the filament, because the penetration of air in the bulb or by the evaporation of the cement that attach the bulb to the reflector. This problem may cause a drop of 50% of the light output [16]. 3. Degradation of the reflector, characterized by the loss of the dichroic reflective film or a white or yellow coating of oxides developed over the reflector surface. The degradation of the reflector may promote the reduction of the light output up to 60% [16].

 

13.7.1.2  Band-Pass Filters

They are placed between the bulb and the light pipe. As the light source of QTH devices produces white light and infrared, two types of band-pass filters are used to make the device emits blue light with reduced heat, eliminating a significant amount of unnecessary light. The UV band-pass filter helps to exclude the luminous energy with a wavelength smaller than 400 nm, on the ultraviolet range, which

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..      Fig. 13.10  The UV and infrared band-pass filters. a New; b damaged

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The early QTH light-curing units, namely  countertop units, contain all the functional parts, such as the light source, filters, and fan in one box located far from the hand of the operator. The light was conducted through a flexible cord with an optical fiber bundle or a conductive fluid. The great advantage of those devices was that the noise of the fan and the heat produced by the light source were located far from the operating field [87]. However, more than 20% of the optical fibers would break due to folding or acute curvature of the cable during the use and due to the extreme optical fibers fragility, which generally have to be replaced due to the loss of the light output [16]. They are no longer used in the current devices. The light-curing units with a hard light guide or pistol shaped are the most commonly used nowadays [87]. On this model, the light bulb, filters, and light guide are held by the operator during the use. The light guide is an optical fiber 13.7.1.3  Light Guide bundle sheathed by an amber glass or metal coat with a The light guide, also called light pipe or tip, delivers the fil- length between 38 and 85 mm  (. Fig.  13.11a–e) [16]. The tered light energy to the area of application, inside the oral thin coating of amber-colored glass has a refractive index cavity [16]. It is basically a fiber optical bundle that varies in that the light trying to escape is reflected internally back, size, shape, and diameter according to manufacture of light-­ reducing the loss of light intensity through the sides of the curing unit and can be a flexible cable or a hard tip [16]. guide. The diameter of the guide on the tip may vary between

does not contribute on the polymerization of the resinous materials and may damage the eyes. The infrared band-pass filter blocks the infrared radiation, above 500 nm, generated by the halogen bulb. It also does not contribute on the polymerization and may generate heating of the tooth structure, promoting irreversible damage to the pulp and soft tissues which are being irradiated [16]. The filters must be cleaned on regular bases to remove any deposited residues that may reduce the passage of the light. On those cases, a cotton swab soaked on a camera lens cleaning solution may be used [16]. In . Fig.  13.10a, b, new and the degraded band-pass filters are shown, after a great number of heating and cooling cycles [88]. The filters degradation blocks the passage of light, resulting on an inefficient light curing.  

 

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..      Fig. 13.11  Light guides. a Metal sheathed guide; b glass sheathed guide; c turbo guide; d acrylic guide; e light guide of small diameter for areas of difficult access

2 and 13 mm, depending on the of application place and the access [16]. Generally, the diameter is around 7–8 mm [16]. The varieties of the interchangeable light guide shapes allow a more ergonomic use in several clinical situations. Some manufacturers produce a turbo light guide, which increases the light output in up to 52%, by decreasing the diameter of the exit in relation to the entrance of light (. Fig. 13.11c) [15, 16, 41, 87]. Recently, to reduce the cost of the devices, the manufactures started to produce light guides made with polymers, which are intended to be disposable [16]. This type of guide must not be touched on the sides during the light curing, avoiding that part of the light transmitted would be lost (. Fig. 13.11d) [15]. The light transmitted through the light guide tip tends to be concentrated in the center of the optical fiber bundle, with a significant reduction on the periphery. That inhomogeneous emittance distribution across the light tips may cause a nonuniform curing of the composite increment which receives the light, being greater on the central area (. Fig. 13.12). To evaluate the existence of large discrepancy on this distribution, a piece of cardboard or thick paper can be placed on the tip of the guide and then turning the light on and observing if it is or not evenly distributed [16]. The optical fiber guide is composed by several fibers grouped. To evaluate the quality of the guide, it can be removed from the device and placed over the pages of a book and observe the image formed. On the good quality guides, the environmental light enters the optical fibers and reaches the paper, being reflected back and forming a clear image on the tip of the guide. On low-quality guides, the formed image is not clear (. Fig. 13.13a, b). An important aspect on the maintenance of the optical fibers is to avoid its contacts with the uncured composite, because it will stick to the tip of the guide and adversely affect the passage of light (. Fig. 13.14a, b). For this reason, it must be covered by a clear PVC cling  film sheet before the use, which will not block the passage of the light.  

 

 

 

 

..      Fig. 13.12  Image of the beam profile in a two-dimensional representation of the emittance distribution. An inhomogeneous distribution across the light tip can be observed. The red area represents a greater emittance

13.7.1.4  Cooling fan

This component promotes the air circulation around the light bulb, avoiding the overheating of the internal components of the light-curing unit, and it must be kept  working the entire time of light production and for a certain time after the end [87]. The cooling fan is responsible for the characteristic noise of the QTH unit, which must never be used if the fan is not working, because this would result in the overheating and burning out of the incandescent tungsten filament [41, 87]. 13.7.1.5  Voltage Regulator

It allows maintaining a constant emission of light, without having interferences of the electrical oscillations of the power supply [41]. According to Fan et al., line voltage oscillation of just 10 volts may result in up to 30% reduction of the composite’s depth of cure [29]. The unit which does not have this integrated component must be connected to an external regulator. 13.7.2  Plasma Arch Unit

On the plasma arch curing units (PAC), the source of light emission is a bulb with xenon gas and two electrodes, separated by a small space. A very high electric current is used to produce an electric arch between the electrodes, creating light through the ionization of the xenon gas surrounding it, forming plasma by the disintegration of the atoms of the gas [11, 87]. The plasma is a highly energized and ionized glowing environment, with very high temperature, that produces

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b

..      Fig. 13.13  Light guides of different qualities placed over the same printed word. a In a good-quality light guide is possible to clearly see the word; b in a budget poor quality light guide, the image suffers distortion

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..      Fig. 13.14  a Unprotected light guide with composite residues bonded to the surface; b light guide correctly protected by clear PVC cling film

a

b

a radiant white light. That is filtered to remove the ultraviolet and infrared heating radiation, making the device to emitt blue light [3, 87, 91]. Of all the produced energy, only 0.2% is used for the light activation. The radiant emittance may reach 2400 mW/cm2, emitting light with an emission spectrum between 380 and 500 nm, working with all photoinitiators (. Fig. 13.15). Their  

higher emittence was claimed to substantially reduce the curing time. Some manufacturers claimed that a curing for only 3 s with PAC would produce similar material properties, compared to 40 s of curing with QTH devices [47, 87, 91]. The lifespan of these units is greater than the ones of the QTH and may vary from 500 to 5000 h [97]. It presents a flexible cord with a conductive fluid, eliminating the fracture

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problem commonly found on optical fibers’ bundle cords (. Fig. 13.16). The cost of the equipment and its maintenance is higher in relation to the QTH devices [91]. The PAC units showed negative effects on the marginal integrity of the restoration. That was due to the polymerization stress, related to the higher radiant emittance and reduced pre-gel phase. Besides, the raising of temperature turned its safety questionable [91].  

Radiant flux

Absorbance (AU)

Camphorquinone Phenyl-propanedione Lucirin TPO

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..      Fig. 13.15  Emission spectrum of a PAC curing unit (Sapphire – DenMat) (blue area) in relation to the spectral absorption profiles of the more commonly used photoinitiators (lines)

13.7.3  Argon-Ion Laser Unit

The word LASER is an acronym for light amplification by stimulated emission of radiation. For the light production, the device has the ionized argon as the active medium, inside an optical resonator cavity. It produces laser light by a quantum process known as stimulated emission of radiation. The argon-ion laser units (AL) have been used for curing of resinous materials, emitting monochromatic blue light in a very narrow emission spectrum, from 457 to 514 nm, coincident with the absorption spectrum of the camphorquinone. The peak of emission occurs in 488 nm, without production of infrared or ultraviolet (. Fig. 13.17) [3]. The light beam produced by the laser is coherent, with all photons with same frequency and polarization, besides being collimated, with photons in the same direction of motion and minimum divergence. These characteristics result on a large amount of energy concentrated on a small irradiation area. In addition, there is no significant loss of energy reaching the material when the distance between the tip of the light guide and the composite is increased, different of what is observed with the other kinds of curing units [36, 91, 107]. The radiant emittance varies from 700 to 1.200 mW/cm2. However, due to the typical photons concentration of the laser devices, the risk of damage to the retina is increased, and there is the need to use safety glasses, for the dentist and patient, to avoid the contact with the light on a direct and/or reflected way [36, 43]. The AL units have as disadvantages the high cost and the non-polymerization of  

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..      Fig. 13.16  Plasma arch curing unit (Sapphire – DenMat)

Radiant flux

Absorbance (AU)

Camphorquinone Phenyl-propanedione Lucirin TPO

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460 480 Wavelength (nm)

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..      Fig. 13.17  Emission spectrum of an argon-ion laser curing unit (AccuCure – Laser Med) (blue area) in relation to the spectral absorption profiles of the more commonly used photoinitiators (lines)

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..      Fig. 13.18  Argon-ion laser curing unit (AccuCure – Laser Med)

the composites with photoinitiators other than camphorquinone [69]. In addition, the emittance is also very high, which reduces the curing time but also the pre-gel phase, increasing the shrinkage stress. An example of an AL device is presented in . Fig. 13.18.  

13.7.4  Light-Emitting Diode Unit

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The light-emitting diodes, or LED units replaced the QTH devices for light-activation of the composites [41]. The LED technology was originally developed by NASA to stimulate the growing of plants in space, and it is frequently used on electronic devices and computers [115]. The light is produced through a quantum process of luminous radiation emission called electroluminescence, using junctions of doped semiconductors (p-n junctions) for the generation of light [107]. Under this situation, holes and electrons recombine at the LED junction creating light that is focused by a small lens. The composition of the semiconductor materials is the factor which determines the wavelength and color of the light produced, without infrared emission. Therefore, it does not require band-pass filters. On the case of the blue wavelength LED, the semiconductors are composed of indium gallium nitride (InGaN) with an emission spectrum between 450 and 490  nm and a peak at 470 nm, producing an almost ideal bandwidth of the light, corresponding to the absorption range of camphorquinone (. Fig. 13.19) [107].  

>> The LED produces light through a quantum process of luminous radiation emission called electroluminescence. Only blue light is created, without infrared emission.

The LED lifespan is about 10,000 h, in comparison with the 80–100 h of the QTH lamps [97]. LEDs consume less electric energy than QTHs and generally do not require external cooling. The low heat emission, an important aspect in rela-

Radiant flux

Absorbance (AU)

Camphorquinone Phenyl-propanedione Lucirin TPO

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440 460 480 Wavelength (nm)

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..      Fig. 13.19  Emission spectrum of a narrow-spectrum blue LED curing unit (blue area) in relation to the spectral absorption profiles of the more commonly used photoinitiators (lines)

tion to the pulpal tissue damage risk, is one of the great advantages of those devices [18]. However, light-activated materials which do not use camphorquinone as the photoinitiators may not be properly cured by devices emitting only blue light. Chronologically, the LED units may be classified into first, second, and third generations. The first light-curing units produced, classified as the first generation, presented a simple design, consisting of an array of several relatively low-­ powered LED chips assembled together, resulting on devices with radiant emittance smaller than 200 mW/cm2 (. Fig. 13.22a) [68]. They showed poor curing performance compared with conventional QTH lights, requiring much longer exposure times to provide a similar level of curing. The second-generation devices are characterized by having a single high-power LED chip, of much higher surface area and radiant emittance than the first-generation ones (>1000 mW/cm2) (. Fig. 13.22b). The devices of this generations have an improved design; are more ergonomic and portable, with or without batteries (. Fig. 13.20a, b) [18]. The third-generation devices contain, in addition to the blue wavelength  emission LED (450–490 nm), others that emit light on the violet wavelength (around 400 nm). They are called polywave or broad-spectrum light-curing LED units [85]. As examples on the market are Valo (Ultradent) and Bluephase (Ivoclair/Vivadent) units, allowing the light curing of resinous materials with photoinitiators different from camphorquinone (. Fig.  13.21). The Valo unit has an emission spectrum between 395 and 480 nm, having LEDs with three different emission peaks, which are 405  nm (1 LED), 445 nm (1 LED), and 465 nm (2 LEDs) (. Fig. 13.22c). The radiant emittance can be adjusted to 1000 mW/cm2, 1400 mW/cm2, and 3200 mW/cm2. The Bluephase device has two LEDs, which emit blue light with a peak at 470 nm, and one LED with peak at 410 nm. It has programs which allow adjusting the radiant emittance on 650, 1200, and 2000 mW/ cm2. The programs for large irradiance are indicated for cementation of indirect ceramic restorations and bonding of  

 

 

 

 

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..      Fig. 13.20 Second-generation narrow-spectrum LED curing units. a Free Light Elipar 2 (3 M); b Radii-cal (SDI)

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Camphorquinone Phenyl-propanedione Lucirin TPO

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..      Fig. 13.21  Emission spectrum of a polywave third-generation LED light-curing unit base (Valo – Ultradent) in relation to the spectral absorption profiles of the more commonly used photoinitiators (lines)

orthodontic brackets. The main advantage of polywave LED units is that all composites could be properly polymerized with them. In terms of composite wear resistance and curing effectiveness, there is no consensus in literature whether monowave are better or worse than polywave units. Minor differences in both directions have been reported from different studies [1, 40, 63, 71, 93]. A study reported that polywave curing units could provide a higher conversion degree from Bis-GMA/TEGDMA mixture when compared to monowave, regardless of initiator type [67]. However, it was highlighted that the homogeneity of the radiation beam, related to an accurate collimation of the different light-­ emitting diodes, is crucial. Price et  al. commented that the not uniform spectral distribution in polywave curing lights tips could affect the resulting properties of some light-curing resins and their potential long-term success [82]. Several

authors, through imaging capture of the beam profile, concluded that, regarding emittance uniformity, third-­generation units have hot spots of high emittance related to the location of the LED chips [84] and thus a nonuniform emittance output [99]. . Figure 13.23 shows the lack of emittance uniformity of different polywave light-curing units. However, it can be clinically appreciated that, depending on the light-curing unit orientation, different parts of the composite resin restoration in a MOD cavity would receive very different wavelengths and energies. The wide range of spectral radiant energy emitted on the surface consequently result in a nonhomogeneous curing of the restoration [83]. It could be suggested to move the polywave lamp by only few millimeters when light curing a resin-based restoration. However, the results of beam inhomogeneity may not be so clinically evident [84].  

>> The polywave curing units have lack of emittance uniformity for the light produced by the different LEDs, creating hot spots of high emittance related to the location of the LED chips. The not uniform spectral distribution in curing lights tips could affect the resulting properties of the composites, by a nonhomogeneous curing of the restoration, impairing their potential long-term success.

13.8  Monitoring of the Light Output

For the proper curing of a composite, it is necessary a light source with correct emission spectrum and enough light intensity. A very important point, when performing the light curing of a restorative material, is the fact that the dentist is not capable to distinguish between a correctly and insufficiently cured composite, due to the fact that an improper

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..      Fig. 13.22  LED chips of different generations of light-curing units. a First generation, array of several relatively low-powered LED chips assembled together; b second generation, a single high-power LED

chip (Radii-cal – SDI); c third generation, group of high-power LEDs with different emission spectrum (Valo – Ultradent)

light-curing device is capable to polymerize the surface of a composite layer as good as a proper one [16]. Different from the chemically activated composites, which cure on a uniform manner if the mixing of the two pastes was effective, the light-activated materials polymerize only where the light is capable to reach, since it is attenuated during the passage through the material [16]. Frequent evaluation should be performed to ensure that the device is emitting the required minimum amount of light. Despite what may be thought, the bare eye is not sensible enough to detect any change on the light-curing unit emittance, being required the use of electronic sensors [16]. The radiant emittance, radiant exitance, or just emittance of a light-curing unit is the radiant power (flux) emitted by a surface per unit area. It is measured when the light tip is in direct contact with the light detector. The SI unit

for it is the milliwatt per square centimeter (mW/cm2) [3, 16, 87]. The most precise and recognized method for radiant emittance evaluation is the integration sphere, being considered the gold standard. However, it is very expensive and not adequate for the dental office use. The radiometer is a less expensive device developed for this purpose [16]. On the other hand, it cannot be calibrated and provide only approximate values, being adequate just for relative evaluation. It should be frequently used by the dentist to follow the emittance of his device, detecting any significant changes that could impair the proper curing procedure. Due to its clinical importance, some companies provide curing-light charging stations with an integrated radiometer (. Fig. 13.24). For the QTH units, the radiometer measures the wavelength range from 400 to 550  nm (. Fig.  13.24a). In this  

 

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..      Fig. 13.23  Images of the beam profile of different third-­generation polywave LED units a–d, showing nonuniform emittance outputs, in comparison to the homogeneous beam profile of a QTH unit (E). Hot

spots of high emittance are related to the location of the LED chips. a Translux (Kulzer), b Valo (Ultradent); c Bluephase (Ivoclar Vivadent); d Demi Ultra LED (Kerr); e Swiss Master Light (EMS)

range is the maximum spectral absorption of camphorquinone, the most common photoinitiator of the resinous materials [16, 87]. Due to the fact that on the regular LED units the emission spectrum is narrower, on the range from 460 to 470 nm, specific radiometers have been developed for them (. Fig. 13.24c). Therefore, to measure the irradiance using a radiometer, it is important to take into account the type of light-curing device which is being evaluated (QTH, PAC, AL, or LED) and the spectral measurement range of the radiometer. The radiometer with a broad wavelength measurement range will measure every light produced by a LED unit, but a dedicated LED radiometer, with a narrower measurement

range, will not measure the entire energy emitted by a QTH or PAC. Most regular radiometers are also not adequate for measuring the radiant emittance of polywave third-­ generation LED units, although some manufactures have developed more advanced radiometers for those devices, such as the Bluephase Meter II (Ivoclar Vivadent). Since to the distance between the light tip and the target can vary, the amount of energy measured when the light tip touches the detector of a measuring device (radiant emittance) does not represent the actual amount of light that will reach the material to be light cured. The radiant power incident on a known surface area is called irradiance (incident

 

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..      Fig. 13.24  a Radiometer for QTH curing units (3 K, Spirith Health); b heat/glare radiometer (Demetron); c radiometer for narrow-­spectrum LED devices (Kondortech)

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irradiance). At 0  mm of distance between the light source and the surface of the light detector, the radiant emittance and the incident irradiance will be the same. According to the total energy concept, a proper curing of the composite depends on the amount of energy absorbed by the material and can be summarized by the multiplication of irradiance by the time of exposure. The more recent studies showed that an energy density of 16 J/cm2 (16,000 mWs/cm2) is the necessary energy dose to properly cure a 2 mm increment of the composite. The curing time necessary to reach this energy dose will depend on the final irradiance by the lightcuring device. Considering a composite in direct contact with the light source (emittance = irradiance), for a curing unit with radiant emittance of 400 mW/cm2, an exposure time of 40 s would be necessary (40 s × 400 mW/cm2 = 16,000 mWs/ cm2 or 16 J/cm2), while for a curing unit with radiant emittance of 800 mW/cm2, an exposure time of just 20 s would be enough (20 s × 800 mW/cm2 = 16,000 mWs/cm2 or 16 J/cm2). Besides to control the visible light emission, the curing units that generate infrared radiation, such as the QTH and PAC, must be evaluated using a heat/glare radiometer (. Fig.  13.24b). They measure the emittance in the wavelength spectrum between 520 and 1100  nm. The infrared emittance higher than 50 mW/cm2 will result on an intense overheating of the tooth structure and damage to the pulpal tissue. According to Zack and Cohen, on a study applying heat on monkey’s teeth, an increase of the pulpal temperature greater than 5.5 °C leads to pulpal necrosis in 15% of the cases [120]. If the dentist does not have this type of device, the pinky finger can be placed over the tip of the light guide and the device activated for 3 consecutive min. If there is the sensation of unbearable heat, the infrared band-pass filter has a defect [16].  

High-powered LED units, such as the second- and third-­ generation ones, can also produce potentially high thermal emissions and damages to the pulpal tissue. Despite the absence of infrared emission, the high emittance levels can increase the chip temperature. Therefore, those devices need a way to dissipate the internal heat, using thermal conductive materials in the structure or cooling fans. The evaluation of a new light-curing unit with a radiometer should be performed to detect any manufacturing defect, and the baseline radiant emittance be recorder for relative further comparisons. When measuring the emittance, the same light guide must be used every time the test is performed, removing any cross-infection control barriers from the tip. The surface of the light guide tip must be positioned parallel to the surface of the radiometer port. The test must be repeated periodically, and if any reduction in the light output is noticed, the components of the device must be evaluated [16, 87]. An insufficient polymerization reduces the strength of the material, increasing the wear, solubility, and water sorption, making it more susceptible to staining It also increases the potential of pulpal irritation, due to the leaching of unpolymerized free residual monomers [16]. Tip

The evaluation of a new light-curing unit with a radiometer should be performed, and the baseline radiant emittance be recorded for relative further comparisons. The unit must be frequently checked to ensure the use of the adequate amount of energy necessary for the selected curing time.

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Moreover, the autoclave sterilization promotes the clouding of the optical fibers on the light guide tip after several cycles, reducing the passage of light. Therefore, if there are residues deposited on the light guide, or after 50 cycles of sterilization, the surface must be polished with fine grains polishing discs or rubbers points, recovering the free passage of the light. Between each patient, the external surface of the light curing must be disinfected, and the light guide must be disinfected or sterilized in autoclave. Then, the light guide must be covered with clear PVC cling film sheet, as an infection control surface barrier, as well as the area where the dentist holds the device. 13.9  Curing Protocols

The knowledge about the kinetics of the composite polymerization, the cavity configuration factor, and shrinkage vectors direction allowed the development of special clinical procedures to reduce the negative effects of the polymerization shrinkage. Among them are the incremental layering technique, as described on the following chapters, and the different curing protocols [3, 87]. The light-curing protocols may be divided in conventional, where the irradiance is maintained in the full power during the curing time, and gradual, where the irradiance changes during the cycle. 13.9.1  Conventional Protocol

As known as uniform and continuous or full-power curing cycle, the maximum power output is applied from the beginning to the end of the cycle, and it is maintained constant. In order to obtain an ideal polymerization, it is important to guarantee that the restorative material will receive the necessary energy density [3, 80, 92]. Some studies evaluating the radiant emittance of light-curing devices in use on dental clinics have shown that 60% of the analyzed devices had an emittance smaller than 400 mW/cm2, which is the minimum acceptable level for the 40s of exposure and a 2  mm increment [87]. Therefore, even using the exposure time recommended by the manufacturer, the composite will not reach good mechanical properties due to the low emittance [87]. Other important aspect is that the light must be maintained steady over the surface of the restoration, during the entire irradiation time of the cycle. For that, the diameter of the light guide must cover the entire area to be cured. If the diameter is smaller than the preparation, the curing must be performed in areas, and the cycle must be repeated on each one. If there are two preparations, the curing of the first one must be concluded, with the light being applied during the total required time for the first preparation. After that, the procedure is repeated on the second preparation. That is, the light must never be moved from one preparation to another during the irradiation, trying to accelerate the process, because none of them will receive the required light energy dose.

Tip

If there are two preparations, the curing on the first one must be concluded before starting on the second. Therefore, the light must never be moved from one preparation to another during the irradiation, trying to accelerate the process, because none of them will receive the required light energy dose

Another point to be considered is that, with exception to AL, the curing-light beam has no collimation and the light beam spreads in a certain angle. When the distance between the light guide tip and the composite is increased, the light spread is higher, reducing the amount of incident irradiance. Therefore, distance from the light guide tip to the material to be cured should be as close as possible, generally 1–2  mm. The incident irradiance striking the material is inversely proportional to the distance, due to the divergence of the light beam and the light scattering by the molecules in the air on the path to the restoration, reducing the amount of photons that may reach the surface of the composite [80, 88]. However, the ideal distance may not always be possible on several dental procedures, due to the anatomy of the tooth or the distance from the occlusal surface to some walls, such as the gingival walls on Class II preparations. Therefore, distances from 5 to 6  mm are frequently found due to the depth of the preparation (. Fig.  13.25) [88]. In general, the light dissipates proportional to the square of the distance. That is, if the distance between the material and the light is doubled, the incident irradiance will be reduced to 1/4 of the initial one [16].  

..      Fig. 13.25  Real curing distance on the proximal box of posterior teeth when the composite is applied on the gingival wall

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When the distance between the light tip and the composite is increased, the light spread is higher, reducing the amount of incident irradiance. Therefore, distance from the light guide tip to the material to be cured should be as close as possible, generally 1–2 mm.

800 700

mW/cm2

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400 300

. Figure  13.26 shows data of the relation between the dis 

tance of the light guide tip to the composite surface and the incident irradiance reaching on the surface, using different QTH and LED light-curing units. It can be observed that when the distance was between 5 and 8 mm, every unit tested, despite the radiant emittance measured on the direct contact with the tip of the light guide, reached the critical level of incident irradiance below 400 mW/cm2 on the material surface, showing the importance to maintain the light guide tip as close as possible to the material to be cured. It is also observed that irradiance reduction increasing the distance was greater for some devices than others, indi-

500

200 100 0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1617 18 1920 Distance (mm) Optilux Emitter A RadiiCal

..      Fig. 13.26  Relation between the distance of the light guide tip to the composite layer surface and the actual irradiance measured on the surface, using three different light-curing units, QTH – Optilux/ Demetron; LED – Emitter A/Schuster; LED – Radii-cal/SDI)

a

b

c

d

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..      Fig. 13.27  Angle of beam spread of different light-curing units. a Optical fiber light guide (CLK 200 – Kondortech); b optical fiber light guide (Free Light Elipar 2, 3 M/Espe); c light guide free curing unit (Radii-cal, SDI); d light guide free curing unit (Valo, Ultradent)

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..      Fig. 13.28  Position of the light guide tip in relation to the occlusal surface inside the simulated oral cavity, with a mouth opening of 43 mm. Depending on the bend of the light guide, the incident beam angle in relation to the occlusal surface may vary. a, b Light-curing

units with optical fibers light guide; c light guide free curing unit with LED chip on the tip but with a bend on the handpiece (Radii-cal, SDI); d light guide free curing unit with LED chip on the tip, with a straight handpiece (Valo, Ultradent)

cating that the angle of beam spread varies from device to device (. Fig. 13.27). Trying to increase the irradiance, some manufacturers produced tapered light guides with the tip of smaller diameter than the entrance of light, called turbo light guides (. Fig.  13.11c). Even though this characteristic may concentrate the light on a smaller area on the tip of the light guide, increasing the irradiance when on direct contact with the material, it has an adverse effect on the angle of beam spread, scattering the light even more. The higher is the angle of beam spread, the smaller is the incident irradiance over the material to be cured when the distance is increased. The parallel-walled (standard) light guides present smaller angle of beam spread (. Fig. 13.27a–d). The average adult male open the mouth around 43 mm from upper to lower incisor edges, with a maximum of 55  mm [39]. This represents a very small space, especially when working on the posterior region. Most of the light-­ curing units on the market have a bended light guide to access the posterior teeth. However, in most of the cases, it is hard to place the tip of light guide perpendicular to the occlusal surface of the tooth to be restorated, making the light to strike the restoration at an angle, called incident

beam angle, generally close to 40° (. Fig. 13.28a, b). Another location  where the access is also hindered is  on the buccal surface of the posterior teeth, because the cheeks adversely affect the proper position of the light guide tip. To overcome this problem, some manufacturers developed light guide free curing units. On the unit shown in . Fig. 13.28c, even though the LED chip is on the tip and it has no light guide, the handpiece has an angle bend which adversely affects to place the tip at 90° in relation to the occlusal surface. On the wand-­ style design unit shown in . Fig. 13.28d, there are no angles on the handpiece, and the LED is placed perpendicular to the long axis of the device. That simplifies the access to difficult locations, even on patients with small mouth opening, allowing the light to be applied in right angle  in relation to the surface to be restored. When the incident beam angle exceeds 30°, a large amount of light energy reflects off the surface and is not absorbed by  the composite (. Fig.  13.29). This results in a critical loss of power, adversely affecting the polymerization. On hard-to-reach restoration locations, the incident beam angle is increased, reducing the incident irradiance and the curing effectiveness, increasing the failures possibility.

 

 

 

 

 

 

 

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..      Fig. 13.29  Effect on incident beam angle in relation to the tooth surface and the incident irradiance. At the top of each column, the percentage of the irradiance reduction is presented. The higher is the angle, the smaller is the irradiance

>> In some areas it is very hard to place the tip of light guide perpendicular to the restoration surface, making the light to strike the restoration at an angle, called incident beam angle. The higher is that angle, the smaller will be the incident irradiance and the light curing.

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Another point to be analyzed is that when the curing light penetrates the composite layer, due to its absorption and scattering, the amount of energy that reaches the bottom area is smaller than the one that strikes the surface, reducing the curing efficacy in this region [91]. Therefore, the depth of cure consists on the maximum thickness that each composite layer may be applied to reach a good conversion degree of the monomers on its bottom [87]. According to Rueggeberg et al. [91], increments of 2 mm thick are considered acceptable, since the irradiance and the time of exposure allow the total energy density required [87]. It is recommended  that the microhardness, on the bottom of the composite layer, should reach at least 80% of the value on the surface for a material to be considered properly cured [9]. The depth of cure consists on the maximum thickness that each composite layer may be applied to reach a good conversion degree of the monomers on its bottom.

Besides irradiance, other factors which can interfere on the depth of cure are the shade and translucency of the restorative material. The darker and less translucent the composite, the larger is the addition of pigments and opacifying agents on the formulation; this makes necessary an increase of exposure time or the use of thinner increments (1mm) in order to obtain the same depth of cure and degree of conversion [13,

87, 88]. The kind and size of filler particles on the composition may also interfere on the depth of cure by changing the light scattering. The closer the filler particle size to the wavelength of the curing light, the higher will be the scattering and smaller the light transmission through the composite. The microfilled composites have a significant level of scattering and reduced depth of cure due to this filler characteristic [13]. For the new bulk fill composites, its higher translucency allows a proper curing of increment up to 4–5 mm. Due to all the difficulties to obtain an adequate polymerization on the intraoral environment, the curing time should be increase at least in 50% from the recommended by the composite manufacturer, since this time is calculated on ideal conditions [16]. The time recommended by the manufacturer is the minimum necessary, assuming that all other variables are not interfering. There is no damage for the restoration when receiving more light than the necessary, although the opposite is not true [16]. Tip

Due to all the difficulties to obtain an adequate polymerization on the intraoral environment, the curing time should be increased at least in 50% from the recommended by the composite manufacturer, since this time is calculated on ideal conditions. There is no damage for the restoration when receiving more light than the necessary, although the opposite is not true.

13.9.2  Gradual Curing Protocols

On this technique, the curing speed is diminished through the reduction of irradiance on the beginning of the cycle, prolonging the pre-gel phase [111]. It may be performed on different ways, such as the pulse delay or soft start in ramp and step. Several studies have shown the capacity of these protocols on reduction of the shrinkage stress and improvement of marginal integrity of the restoration. 13.9.2.1  Pulse-Delay Protocol

It is performed only on the last composite increment of the restoration, which is responsible for the sealing of the restoration margins [87]. The preparation must be filled with composite increments of a maximum thickness of 2 mm; each one is light-cured using a curing unit with a minimum radiant emittance of 400 mW/cm2 for 40s. The last increment is light cured for only 3 s with low incident irradiance, for example, 200 mW/cm2 in devices where the emittance can be adjusted, or moving away the light guide tip from the surface. Then the occlusal adjustment and finishing of the restoration are performed, postponing the final curing, increasing the pre-gel phase. After that, the final light curing is performed with the maximum irradiance, during the corresponding exposure time to reach the total energy density of 16 J/cm2 [87].

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mW/cm2

a

Time

Time ..      Fig. 13.30  Graphic representation of the ramp curing protocol. a Automatic; b by hand

13.9.2.2  Soft Start Protocols

With these techniques, the exposures to the light are performed continuously, using light-curing units that have this program on the software, or by hand using conventional units and moving away the light guide tip from the surface [87]. Two methods can be used, which are the ramp and step.

curing is completed with maximum power for 40 s [87, 119] (. Fig. 13.31a, b).  

13.9.2.3  Indirect Curing Technique

In order to either reduce the curing light irradiance or control the shrinkage, an indirect curing technique could be performed. In some clinical conditions, when remaining cavity Ramp Cycle walls are thin, light cure through the access of the cavity The ramp cycle may be performed automatically with light-­ using a high emittance light-curing unit can led to high curing units that already have this curing mode (. Fig. 13.30a) deflection of the remaining tooth structure, in consequence or by hand bringing the light guide close to the restoration of the shrinkage stress at the adhesive interface. Sometimes, (. Fig. 13.30b) [87]. When performed automatically, the irra- an immediate crack propagation could be observed on the diance starts low (generally close to 150 mW/cm2) and remaining cavity wall, leading to postoperative sensitivity increases linearly during around 10s until the maximum out- and risks of fracture in the immediate future (. Fig. 13.22). put, remaining that way  during the rest of the cycle. On the In such conditions, Dietschi and Spreafico [24] suggested to hand method, the light guide tip is maintained for 20 s at a perform an indirect curing technique: The curing tip is posidistance of more or less 2–3 cm from the tooth surface, result- tioned in contact of the residual wall, and the composite layer ing on an irradiance of approximately ±100 mW/cm2, depend- is cured through the enamel and dentin (. Fig. 15.6l and o). ing on the maximum emittance of the curing unit [87]. The The final irradiance on the composite in contact to the prepagreater the maximum irradiance, the greater the distance must ration wall is reduced, due to the light-scattering effect of be [87]. Then, the light guide is gradually brought closer during enamel and dentin tissues, which will increase the pre-gel 10 s up to 1 mm from the surface and kept for 40 s more [94]. phase and reduce the shrinkage stress.  

 

 

 

Step Cycle On this protocol, the polymerization process is started with a relatively low and constant irradiance, which is maintained for some seconds. Consecutively, the light unit automatically increases the power output to a much higher power (usually the maximum of light) for the rest of the cycle. This method can be performed with units that have an automatic program or through a hand technique. On the curing units where emittance may be adjusted or have this curing mode, the restorative material is exposed to the light with low irradiance (100 mW/cm2) for 5–10 s, and the polymerization is completed on the maximum output for the rest of the time. On the hand technique, the light guide tip is maintained at a distance of ±1 cm from the surface (200 mW/cm2) during 10 s. After 5 s, the guide is brought closer to the surface, and the

13.10  Polymerization of Indirect

Restorations

The light absorption of indirect restorative materials depends on their composition, thickness, shade, and opacity. The Beer–Lambert law relates the attenuation of light to the properties of the material through which the light is travelling. Lambert’s law stated that absorbance of a material sample is directly proportional to its thickness (path length). Much later, August Beer discovered another attenuation relation in 1852. Beer’s law stated that absorbance is proportional to the concentrations of the attenuating species in the material sample. The modern derivation of the Beer–Lambert law combines the two laws and correlates the

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a

Time

Time

..      Fig. 13.31  Graphic representation of the step curing protocol. a Automatic; b by hand

a

b

13 ..      Fig. 13.32  a Large cavity on lingual and proximal surfaces of a lateral incisor; b after composite restoration, an immediate crack propagation was observed on the labial surface due to the shrinkage stress

absorbance to both the concentrations of the attenuating species and the thickness of the material sample. Thus, when curing an indirect restoration, light is attenuated by the indirect materials employed, which are commonly composite resins, glass, and polycrystalline (or zirconia) ceramics, and presents different optical and light absorption properties that influence light attenuation during light activation of an underlying resin cement (. Fig.  13.33) [74, 110]. To overcome the effects of curing-light attenuation, dual-cured cementing systems were developed, having both light and chemically activation mechanisms. Some of them are used in combination with adhesive systems containing co-initiators, such as sulfinic acid salts, that produce free radicals and contribute to the polymerization reaction of the resin cements [5, 14]. As  indirect restoration can decrease the degree of conversion promoted by light polymerization of resin cementing systems, increasing the curing time until 60 seconds can be recommended to compensate the light attenuation [56, 65]. Some authors suggested to lute indirect adhesive partial restoration with preheated light-curing restorative composites instead of dual-curing resin cements. Clinically, the use of a composite as luting  

agent could give some  advantages, such as easy excess removal and better biomechanics at the adhesive interface. To limit the difficulties in reaching high degree of conversion, a preheating until 55 °C is suggested [58] in order to obtain a greater mobility of monomer molecules within the resin matrix and enhances free radical formation, which results in a higher degree of conversion and shorten curing time [2, 19]. The increased mobility of monomers at elevated temperature can lead to delayed auto deceleration stage of the polymerization reaction, thus contributing to increased monomer conversion [20]. 13.11  Fiber Post Cementation

Fiber posts are nowadays widely used to restore endodontically treated teeth. They bond well to the tooth structure, which increases retention of the post, reinforces root structure internally, and improves resistance to tooth fracture. However, adhesion inside the root canal can be impaired by several factors, such as the adverse geometric feature of the root canal [105], the peculiar characteristics of the post space

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a

b

c

d

..      Fig. 13.33  a Replacement of a defective indirect restoration on upper molar; b tooth preparation; c luting of a new indirect restoration using dual-cure resin cement. The small penetration of light through the restorative material does not allow a proper photopolymerization

of the resin cement on deep areas of the preparation, requiring the self-curing mechanism for adequate degree of conversion and bonding; d Final restoration

[33], and possible incompatibilities between simplified adhesives and dual-cure resin-based cements [105] One of the most important aspect in luting of a fiber post into the root canal is reaching an adequate degree of cure, at deeper areas, of either the adhesive system or the luting cement [86]. Although self-curing resins exhibit uniform polymerization, the application of this type of resin into the canal followed by the post positioning must be performed very quickly, because polymerization starts  after the two pastes are mixed [34, 117]. However, the use of purely light-­ cured cements is not indicated, because the polymerization is also limited at depths beyond 2 mm, because the influence of reduced irradiance produced by the shadowing of the tooth structure, and the light scattering and attenuation within the resin cement and the post [30, 117]. Therefore, dual-cure cements are the best choice in the fiber posts luting [38, 75]. They have a chemical-curing system that can achieve a more extensive polymerization in dark locations [48], while also providing a light-curing mechanism that allows a rapid initial hardening of the resin cement to stabilize the restoration [118]. Both the light- and chemical-curing mechanisms are complementary but independent [77].

Although chemical curing is responsible for polymerization at sites not reached by light, the chemical polymerization component in some dual-cure resin composites has been described as slower, less effective [12, 79], or virtually ineffective [6, 26]. Therefore, translucent fiber posts were introduced to overcome the problem of lack of curing in deep locations with limited penetration of light [75]. The efficacy of these light-transmitting posts has been supported by several studies [75, 89]. However, some in vitro studies stated that widely used translucent posts have been shown to ineffectively transmit light to the apical region [51]. In fact, even being translucent, fiber posts will limit light transmission to values lower than 40% of incident light, and may not guarantee an adequate degree of conversion of the resin especially at the tip end (. Fig. 13.34) [106]. Thus, in order to reach the maximum degree of conversion possible, besides using a dual-cure resin cement, the increase of curing time is recommended. Clinically, an extended time up to 60 seconds is suggested to obtain the maximum mechanical properties of the luting cements, which are directly related to the clinical performance and outcome of fiber-supported restorations.  

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Iris UV Visible Infrared

Retina Cornea Vitreous humor

Aqueous humor Crystalline

..      Fig. 13.34  Transmission of light through a glass fiber post. The resin cement was applied to the post, on the part intended to be inserted into the canal (on the left of the image), and the light guide was placed on the post tip (on the right side of the image). It is possible to see that the light transmission is reduced during its penetration through the post (red arrow), and no light reaches the resin cement after a certain distance from the light source (asterisk on the dark area)

13.12  Ocular Hazards of Curing Lights

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The light is a kind of radiant energy, and according to its wavelength, the amount of energy carried and its effects can vary. Its interaction with the matter will also depend on the chemical and physical characteristics of the irradiated tissue. Due to the intensity of emitted light, the light-curing units are capable to cause ocular damage to the patient, dentist, and dental assistant. The environmental light enters the eyes through the cornea, located in front of the anterior chamber filled with the aqueous humor (. Fig. 13.35). Then, the beam of light pass through the iris, a type of adjustable diaphragm, and then reach the crystalline, a type of lens capable to focus the light on the retina. It is surrounded by a circular muscle that allows the constant modification of the focal distance of the eye. After passing through the crystalline, the light beam crosses the vitreous humor, hitting the retina. It is formed by a layer of light sensible cells, which are concentrated on the area called fovea centralis. This small area of the retina is the main responsible for the vision [43]. The human eye is capable to respond only the electromagnetic radiation at the wavelength range between 390 and 770 nm, and the brain is able to interpret it as color. However, when considering the harmful effects of the light on the eyes, it is necessary to analyze the invisible wavelength near the visible spectrum, that is, the ultraviolet (770 nm). The different parts of the eye act as filters for the different wavelengths. In . Fig. 13.35, it is shown the components of the human eye and its interaction with the several wavelengths. The cornea is first irradiated and filters the electromagnetic waves with wavelengths smaller than 300 nm, which reduces the amount of UV that enters the aqueous humor. The crystalline absorbs the waves  

 

..      Fig. 13.35  Cross section of the human eye illustrating the path of light and its interaction with the different wavelengths (UV, visible light, and infrared)

with wavelength between 300 and 400 nm, basically avoiding that the UV radiation hits the retina. The visible light freely goes through the cornea and the crystalline, hitting the retina [49]. The excessive exposure and the absorption of the UV radiation by the cornea lead to cellular damage due to the nuclear fragmentation of the corneal epithelium. The loss of the cohesion between the epithelium and the stroma also happens on the crystalline and may cause a progressive loss of transparency, called cataract, due to a cumulative photochemical damage over the lens proteins [116, 121]. For this reason, the UV light-curing units were totally removed from the market. In relation to the damage produced by the visible light and infrared to the retina, Ham et al. described three types of aggressions [44]. The first is the mechanical breaking of the retinal structure, resulting from high-power shock waves, using short radiation pulses absorbed by the retinal pigment epithelium. The second is a thermal damage in the retina, which results from the absorption of enough energy to increase the retinal temperature in at least 10 °C above the body temperature. The third is an actinic damage. It is called actinic, the capability of light to produce chemical changes on determined substance. The actinic effect, also called photochemical, is a result from prolonged exposure to short wavelengths of visible light (400–550 nm), on irradiance too low to increase the temperature in more than some degrees above the body temperature. The parameters which determine the type of damage to the retina are the light intensity, duration of exposure, and the wavelength (color). The intensity that enters in the eye and the duration of the exposure determine if the damage is mechanical or thermal. The thermomechanical damage caused by visible light is intensified by greater irradiance and small wavelength, such as the blue light, which carries more energy and may cause true retinal burn [45, 49]. The greater risks are attributed to the absorption of the focused light on the retina by the melanin granules in the retinal pigment epi-

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thelium, which can produce a significant heating. This can lead to the disruption of the photoreceptor’s outer segment, in relation with the duration of the exposure. Ham et al. [44] showed that the intense blue light, especially on the range of 460–480 nm, caused burn on the retina of monkeys, even on short exposures, smaller than a second. The burns became more serious with the increase of the exposure time, with a mean healing time of 20–30 days. The healed areas became a permanent degenerative tissue, histologically similar to the age-related macular degeneration, which means that the light exposure quickly ages the retinal visual cells and it is an irreversible phenomenon. Using low irradiance and longer exposure time, there is a point from which the thermal effects become minimal or insignificant. On wavelengths range from 550 to 600 nm, corresponding to green and yellow, the retinal temperature is only increased some degrees above the body temperature, and the retina is not damaged even after prolonged exposures. For the wavelengths below 550 nm, the prolonged exposures produce actinic effects on the retina even though there are no thermal damages. There is no clear marked line between the thermal and actinic effects, and there is a point where the photochemical and thermal effects overlap [45]. The action spectrum of the actinic effects on the retina increases exponentially as the wavelength decreases to 400  nm [46]. Below 450nm wavelenght, crystalline begins to absorb a little of the electromagnetic wave, with some photons, between blue and violet spectrum, reaching the retina. According to Ham et al., blue light creates free radicals in the eye in a similar way to what happens with composites [44]. On the retina, these free radicals react with the aqueous content of the visual cells forming peroxides, which are very reactive and cause denaturation on the photoreceptors and severe visual damage. Briefly, the thermomechanical lesions require the intense exposure to light, while the photochemical is caused by prolonged exposures, primarily to blue or near ultraviolet, at levels that probably would be well tolerated if they were transitory [64]. According to the American Conference of Governmental Industrial Hygienists (ACGIH), looking to a blue visible light source for more than 12 min represents a potential risk to the eyes. A positive point is that the light that the dentist or the assistant see is not direct light, but the light reflected by the patient’s mouth, which represents about 20–30% of the emitted light [16]. However, there is the necessity that both patients, dentist, and assistant be protected [16]. For safety use of the light-curing units, it is necessary the use of a light filter, such as orange safety glasses or handheld shields, with optical density capable to filter the blue light [100]. The optical density is the capacity that a lens has to attenuate the passage of light in a wavelength harmful to the eyes. It is calculated in relation to the maximum permissible exposure for each type of light source. The safety glasses or shields offer comfort for the dentist work, which can directly see the place of light application. The safety lens must absorb most of the blue light but allow the observation of the operating field [16]. According to Chain [16], good safety

glasses allow transmission of 1–5% of the light for the wavelength smaller than 450  nm and 50% for the wavelength greater than 550 nm. Tip

55 Always extend curing time. The more you light cure, the best mechanical and optical properties you’ll obtain. 55 Visually check, with proper eyes protection, the curing tip position while curing. 55 With long curing times, it is desirable to control the temperature rise with air blow.

Conclusion The world of operative and restorative dentistry is increasingly turning to the use of polymeric materials. It is evident that the polymerization of adhesive systems, composite resins, and resin cements has a fundamental role in the optical and mechanical performances of the materials themselves. The photopolymerization phase must therefore be considered as a fundamental step in the clinical sequence, which must be carried out carefully and with the right tools. The dentist must understand how the polymerization reaction occurs, as well the influence of the light irradiance on the shrinkage stress, responsible for most of the problems related to composite restorations. The gradual curing protocols are options to reduce the shrinkage stress, besides the use of a layering technique. The clinical use of the light-curing units must be precise, mainly related to the positioning of the light source in relation to the cavity entry, containing the restorative material to be cured. The higher is the distance between the end of the light guide and the surface of the composite, the smaller will be the irradiance and the polymerization. The light source must be placed as close as possible to the surface, avoiding leaning the light guide. An increase in polymerization times can also improve the degree of conversion of the materials, either in direct or indirect techniques. The constant exposure to the visible light can cause damage to the eyes, and protective shields are recommended.

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106. Teixeira ECN, Teixeira FB, Piasick JR, Thompson JY.  An in  vitro assessment of prefabricated fiber post systems. J Am Dent Assoc. 2006;137:1006–12. https://doi.org/10.14219/jada.archive. 2006.0323. 107. Torres CRG, Borges AB, Kubo CH, Gonçalves SE, Araujo RM, Celaschi S, et al. Clareamento Dental com Fontes Híbridas LED/LASER. 2nd ed. São Paulo: Livraria Santos Editora Ltda; 2007. 108. Truffier-Boutry D, Demoustier-Champagne S, Devaux J, Biebuyck J-J, Mestdagh M, Larbanois P, et al. A physico-chemical explanation of the post-polymerization shrinkage in dental resins. Dent Mater. 2006;22:405–12. https://doi.org/10.1016/j.dental.2005.04.030. 109. Truffier-Boutry D, Gallez XA, Demoustier-Champagne S, Devaux J, Mestdagh M, Champagne B, et  al. Identification of free radicals trapped in solid methacrylated resins. J Polym Sci Part A Polym Chem. 2003;41:1691–9. https://doi.org/10.1002/pola.10692. 110. Turp V, Sen D, Poyrazoglu E, Tuncelli B, Goller G. Influence of zirconia base and shade difference on polymerization efficiency of dual-cure resin cement. J Prosthodont. 2011;20:361–5. https:// doi.org/10.1111/j.1532-849X.2011.00721.x. 111. Uno S, Asmussen E.  Marginal adaptation of a restorative resin polymerized at reduced rate. Eur J Oral Sci. 1991;99:440–4. https:// doi.org/10.1111/j.1600-0722.1991.tb01052.x. 112. Versluis A, Douglas WH, Cross M, Sakaguchi RL. Does an incremental filling technique reduce polymerization shrinkage stresses? J Dent Res. 1996;75:871–8. https://doi.org/10.1177/002203459607 50030301. 113. Versluis A, Tantbirojn D, Douglas WH. Do dental composites always shrink toward the light? J Dent Res. 1998;77:1435–45. https://doi. org/10.1177/00220345980770060801. 114. Watts DC, Kaiser C, O’Neill C, Price RB.  Reporting of light irradiation conditions in 300 laboratory studies of resin-composites. Dent Mater. 2019;35:414–21. https://doi.org/10.1016/j.dental.2018.12.001. 115. Whelan HT, Buchmann EV, Dhokalia A, Kane MP, Whelan NT, Wong-Riley MTT, et  al. Effect of NASA light-emitting diode irradiation on molecular changes for wound healing in diabetic mice. J Clin Laser Med Surg. 2003;21:67–74. https://doi. org/10.1089/104454703765035484. 116. Wojno T, Singer D, Schultz RO.  Ultraviolet light, cataracts, and spectacle wear. Ann Ophthalmol. 1983;15:729–32. 117. Yoldas O, Alaçam T.  Microhardness of composites in simulated root canals cured with light transmitting posts and glass-fiber reinforced composite posts. J Endod. 2005;31:104–6. 118. Yoshida K, Atsuta M. Post-irradiation hardening of dual-cured and light-cured resin cements through machinable ceramics. Am J Dent. 2006;19:303–7. 119. Yoshikawa T, Burrow MF, Tagami J.  A light curing method for improving marginal sealing and cavity wall adaptation of resin composite restorations. Dent Mater. 2001;17:359–66. 120. Zach L, Cohen G.  Pulp response to externally applied heat. Oral Surg Oral Med Oral Pathol. 1965;19:515–30. 121. Zigman S. The role of sunlight in human cataract formation. Surv Ophthalmol. 1983;27:317–25.

465

Composite Restoration on Anterior Teeth Carlos Rocha Gomes Torres and Rayssa Ferreira Zanatta 14.1

Introduction – 466

14.2

Basic Concepts About Color – 470

14.2.1 14.2.2 14.2.3

 efinitions – 470 D Optical Characteristics of Natural Teeth – 471 Shade Determination – 477

14.3

Selection of Composite Resin – 482

14.4

Indications of Composites on Anterior Teeth – 483

14.5

Esthetic Analysis of Anterior Teeth – 484

14.5.1 14.5.2 14.5.3 14.5.4

E namel Translucency – 484 Morphology of the Incisal Edge – 484 Surface Texture – 486 Dental Dimensions and Proportions – 488

14.6

Restorative Technique – 492

14.6.1 14.6.2 14.6.3 14.6.4 14.6.5

 revious Clinical Procedures – 492 P Tooth Preparation – 492 Restorative Procedure – 497 The Use of Color Modifiers – 559 Finishing and Polishing – 568

14.7

 urability and Maintenance of the D Composite Restorations – 573 References – 574

© Springer Nature Switzerland AG 2020 C. R. G. Torres (ed.), Modern Operative Dentistry, Textbooks in Contemporary Dentistry, https://doi.org/10.1007/978-3-030-31772-0_14

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Learning Objectives The aim of this chapter is to teach the readers the following topics: 55 Basic concepts about color and optical characteristics of natural teeth 55 How to make the tooth shade determination and select the appropriate composite resin 55 Principles of esthetic analysis of anterior teeth in order to reproduce the natural characteristics on the restorations 55 How to perform the restorative procedure for all kinds of lesions produced by caries or other non-carious origin 55 How to perform restoration of fractured teeth with or without the association of a surgical procedure 55 The reattachment of fractured tooth fragments 55 The use of composite for recontouring teeth 55 The use of color modifiers 55 Finishing and polishing procedure 55 Factors affecting the durability and how to perform the maintenance of composite restorations

14.1 

14

Introduction

The composite resin is the most popular direct restorative material among the clinicians and the most requested by the patients, either for anterior or posterior teeth. Its main advantage is the esthetics because it presents shades compatible with the remaining tooth structure. On anterior teeth, it is the best option to restore the lost shape, function, and esthetics. Another great advantage is its adhesion to the tooth structure, which contributes to the retention of the restorative material and helps to reinforce the remaining tooth structure [31]. The development of the dental adhesives allowed a deep change on the paradigms in relation to the tooth preparation, contributing for the creation of the minimally invasive dentistry. With the recognition of the fact that caries incidence can be significantly reduced or totally avoided, in addition to the fact that some caries lesions can be arrested, remaining as a scar, or even reversed and disappear, the necessity of tooth restoration has decreased considerably. The invasive approach of caries lesions treatment, without giving instructions for patients in relation to the caries as a multifactorial disease, results on the treatment failure in a short period of time. This allows new lesions to occur on other areas of the same teeth and/or on other teeth of the same patient. The restorations do not cure the caries disease and do not promote health by itself and failure earlier than most clinicians believe [3]. As discussed by Roulet and Degrange [32], in the past, young clinicians could work their entire lives with the knowledge that they learned at the dental schools. This is not true anymore, since the adhesives and restorative materials changed and continue to change the way that many restorative procedures are performed. The dentists now need continuing education to update themselves in relation to new alternatives of materials and techniques, to offer the best treatment possible for the patients.

The first composite resin was developed in 1962 by Bowen [8]. It is a polymeric restorative material composed basically by three main ingredients. The first is the organic matrix, formed by a blend of resinous monomers with molecular chains of different lengths, which can chemically bond and form a rigid material. Some of the most commonly used are the bisphenol A-glycidyl methacrylate (Bis-GMA), urethane dimethacrylate (UDMA), bisphenol A polyethylene glycol diether dimethacrylate (bis-EMA), and triethylene glycol dimethacrylate (TEGDMA). Even though the polymerization reaction is essential to form a hard polymer, it results on the volumetric shrinkage of the material by the reduction of the intermolecular distance between the monomers, due to the covalent bonding, creating stress at the tooth-restoration interface [1]. The mean volumetric shrinkage of the current methacrylate-based composites in around 1.3–4% by volume [29, 33]. This shrinkage produces stress on the tooth-­ restoration interface of about 4–8 MPa, which can break the bonding between the composite and the tooth structure, creating marginal gaps and allowing microleakage. This can allow the occurrence of secondary caries lesions, besides causing cracks or fractures on the enamel margin, cuspal deflection, and postoperative sensitivity [1, 10]. The second ingredient is the inorganic filler, composed by small glass or silica particles, which has the objective to increase the mechanical strength of the restorative material [31]. The presence of fillers also reduces the organic matrix content, diminishing the volumetric polymerization shrinkage. In addition, the strontium and barium elements in the filler’s composition give radiopacity to the material, which helps the diagnosis of secondary caries on restorations margins. The filler’s content reduces the coefficient of linear thermal expansion in relation to an unfilled material, although for regular composites it can still be up to three times higher than the tooth structure. It also reduces the water sorption, which can promote material’s degradation and staining [31]. The third ingredient is the silane coupling agent which acts as a sort of intermediary, bonding the inorganic fillers to the organic matrix. It produces the integration of the other two main ingredients, making that all material’s components behaves as a single body, increasing the mechanical strength and reducing water sorption and solubility [31]. >> The composite resins have three main ingredients: organic matrix (resinous monomers that allows polymerization), inorganic filler (glass particles that gives strength), and silane coupling agent (agent that bonds monomers and fillers).

The composites may be classified according to the type and size of the filler particles, because it has a great influence on its mechanical characteristics. The first composites created, also known as conventional or macrofilled, were characterized by having large filler particles, of very similar and homogeneous size, in a Bis-GMA organic matrix (. Fig.  14.1a). They were introduced on the 1960s and had on its composition grinded quartz filler particles, with average sizes larger than 15 μm (15,000 nm), due to the technical limitation on  

467 Composite Restoration on Anterior Teeth

a

b

c

d

e

f

..      Fig. 14.1  Distribution of filler particles on different types of composites. a Macrofilled (Concise, 3M/ESPE); b microfilled (Durafill, Heraeus Kulzer) – the lighter areas correspond to the precured resin filler particles; c hybrid (Surefil, Dentsply); d microhybrids (TPH,

Dentsply); e nanohybrids (GrandioSO, Voco); f nanofilled (Z350, 3 M/ ESPE). SEM images in backscattered electron imaging mode to show the filler particles (1500×)

that time to produce thinner particles by grinding quartz, a very hard material. They had an average filler content of 75–80% by weight and a good compressive strength [31]. The restorations made with these materials had a high surface roughness, due to the large and extremely hard filler particles difficult to cut by the polishing instrument. Therefore, they were not indicated for preparations close to the gingiva because promoted biofilm deposition. Also, this material presented poor esthetic, high levels of wear, and low color stability. When this material suffered abrasion, the polymer between the fillers was removed, leading particles protruding from the surface. With the time those particles were removed creating craters. The craters and the protruding particles produce a rough surface, losing the surface gloss created by the polishing procedures, making the restoration more susceptible to surface discoloration by extrinsic staining [31]. When placed on contact areas, this composite suffered more wear than the natural enamel [31]. Those materials were chemically activated, requiring a previous mixture of two pastes, presenting only one shade. Due to the mixture, air bubbles used to be incorporated into the material, increasing the porosity of the restoration. In addition, the working time was short and the color stability was reduced, due to the degradation of some chemical components, such as the amines [31].

The amount of composite excess at the restoration’s margins to the removed was also greater, due to the application in a single increment. This type of composite is no longer used. On the 1980s, an evolution of the conventional materials came to the market, presenting thinner filler particles, with the average size of 8 μm [31]. The microfilled composites were introduced as an alternative to solve the problems of high roughness and unsatisfactory gloss of the macrofilled materials. They present as filler particles the pyrogenic or colloidal silica, with mean filler particle size of 0.01–0.04 μm (10–40 nm), resulting on a very smooth surface after polishing, with less biofilm retention and extrinsic staining (. Fig. 14.1b) [3, 31]. They present a surface roughness average (Ra) of approximately 0.035 μm, about ten times less than the conventional macrofilled composites (Ra = 0.30 μm). However, there was a technical problem to manufacture a high filler load when using those particles, due to the greater surface area to volume ratio, resulting in a too viscous material. To increase the total filler loading without interfering on the viscosity, many manufacturers added to the formulation pre-cured resin filler particles. They are prepared by adding a large amount of silica particles into the organic matrix, resulting in a viscosity inadequate to the clinical use. The material is polymerized  

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and grinded to form small particles. Those particles are then low surface roughness. The hybrids composites have a filler added to more organic matrix and silica fillers, creating an loading of about 75–85% by weight, which produces adequate adequate viscosity for clinical use. Even with this process, the strength of the material and allows it to be indicated on both microfilled composites have smaller filler loading in relation posterior and anterior teeth. They have a mean filler particle to the other ones, resulting in lower mechanical strength and size of 0.04–5 μm (40–5000 nm), which creates a smoother wear resistance. They present an average filler loading of surface and an acceptable esthetical results [1, 3]. 35–60% by weight [31], which results in small compressive To overcome the yet  unsatisfactory polishing of the strength. They are contraindicated for situations that undergo hybrid composites, the manufacturers reduced the size of the high occlusal load, such as on the restoration of the incisal larger filler particles used on those materials, maintaining a edges, on the occlusal surface of the posterior teeth, and on high filler loading but having a significant improvement of the lingual surface of the anterior teeth where there is occlu- the polishing results, being named microhybrid composites. sal contact or disocclusion guide. They have a higher volu- They present a filler loading of approximately 75–85% by metric shrinkage and a smaller depth of cure, due to the fact weight, with good strength, but the larger particles are not that the small particles adversely affect the light penetration larger than 1 μm, having a mean filler particle size between inside the material [3]. They are excellent in places where a 0.04 and 1 μm (40–1000 nm). They are indicated for anterior high polishing is required, such as on the restorations close to and posterior teeth (. Fig. 14.1d) [1, 3]. A nanoparticle is commonly identified as a particle the gingival margins or as on a surface layer of restorations of the labial surfaces of anterior teeth, where the gloss has a between 0.01 and 0.1 μm (10–100 nm) in size, therefore, great influence of the final esthetic outcome. The surface below the wavelength of the visible light. Particles with nanoroughness of the polished material is similar to enamel and is metric sizes, such as the pyrogenic silica used on the microkept for a long time. In general, they become more translu- filled composites or others, have a large surface area to cent with whiter shade after curing [3]. Some brands of volume ratio and, therewith, high surface energy. When added to the composite formulation beyond 40%, it creates microfilled composites are still available on the market. Considering that the greater the filler loading, the smaller an extremely viscous mass that may not be processed and the resinous content and the volumetric shrinkage of the used as a restorative material. To overcome this problem, the material, the manufacturers tried to add the maximum of manufacturers found a way to chemically inactivate the surfiller possible in the organic matrix. They observed that when face of the freshly generated nanoparticles, reducing its surusing particles with similar size, despite its dimensions, a face energy and its effects of increasing the viscosity. maximum limit of incorporation was reached in a material Therefore, the inactivated nanoparticles were added to the densely packed, with the particles the maximum close to each microhybrid composites, increasing, even more, the filler other. In an attempt to incorporate even more inorganic con- loading, because it occupies the spaces between the smallest tent, it was tested the addition of particles even smaller than particles. This material was named nanohybrid composite. the first ones, trying to fill the gaps between them. The spaces According to the manufacturers, due to the fact that the left between these smaller particles were then filed with even nanoparticles are smaller than the wavelength of visible light, smaller ones. This method for increasing the filler content the light absorption does not occur on those particles, and creates the concept of hybrid composite (. Fig. 14.1c). They the light is transmitted through the material, increasing its associate the advantages of microfilled composites with the translucency. This would help to create a “chameleon effect,” strength of the composites with larger particles, due to the allowing the adjacent and underlying tooth structure to association of fillers with different sizes. To reduce the prob- reflect light through the restoration, which blends the restolems of the high hardness of the quartz particles, softer or ration with surrounding tooth remaining and improves the more friable glasses were developed, such as the barium fluo- esthetic outcomes. The addition of nanoparticles improved rosilicate-aluminum glass, ceramic glass, zirconium-­ some characteristics of the material, but in general it has a containing glass, lithium-aluminum-silicate glass, or similar clinical behavior in relation to the traditional microstrontium glass [1]. Those filler are easily cut by the polishing hybrid composites, with the same indications, advantages, instrument and results on a smoother surface than the mac- and disadvantages (. Fig. 14.1e) [28, 42, 46]. Another kind of composite according to the filler partirofilled ones, increasing also the long-term polish retention. This type of glass has also turned the material more cles is called purely nanofilled. This materials present indi­radiopaque, simplifying the detection of secondary of caries vidual nanoscale particles of 20 nm; and also nanoclusters of on the restoration’s margins [31]. The filler particles are gen- those nanoparticles, with mean particle size of 0.075 μm (75 erally obtained by grinding glass, resulting in irregular shapes. nm). The nanoclusters are produced by a sintering process, However, this technique to manufacture limits the size of the which results in loosely agglomerated nanoparticles. obtained particles, being hardly smaller than 0.5 μm (500 nm) Although structurally different from the regular dense filler [28]. Another way to produce particles is the sol-gel process, particles found in other composites, these nanoclusters using liquid substances as precursors, resulting on spherical behaved similarly in terms of providing high filler loading, fillers of several sizes. The larger particles presented on these which gives strength to the material. In . Fig.  14.1f, the composites increase the strength, while the smaller ones fill nanoclusters of spherical shape can be observed. During the the spaces between them, resulting in a high filler loading and polishing, the nanoclusters are easily  cut, resulting on a  

14

 

 

 

469 Composite Restoration on Anterior Teeth

superficial smoothness similar to a microfilled composite. They result on a better polishing than the microhybrid materials, even though are similar to the modern nanohybrid composites [28]. According to the manufacturer, the wear rate of the clusters is closer to the wear rate of the surrounding matrix, increasing the polish retention. They are indicated for both posterior and anterior teeth and present good strength and polishing. The composites may also be classified according to its viscosity in low, medium, or high viscosity (. Fig. 14.2a–c). The low-viscosity or flowable composites generally have smaller filler loading than the others, which is responsible for its flowability, but results in inferior mechanical properties and higher wear rate. They also generally present a larger volumetric shrinkage [31]. Even though they are easy to use and have good wettability and handling properties, its clinical indications are limited. They are indicated for: Class V restorations, because this region undergoes compressive and tensile stress but has no direct contact with the opposing tooth; as the first layer under composite restorations on posterior teeth, because it promotes a better adaptation to the internal angles of the preparation; on restorations of small preparations in the occlusal surface of posterior teeth; as pits and fissure sealants; and for repair the defective margins of pre-­existing restora 

tions. Some brands have different flowability levels, covering more indications. In the recent years, flowable composites with a higher filler content were developed, increasing its indications for some more stress-bearing situations. The medium-viscosity or conventional composites are considered of universal indication, for both anterior and posterior teeth, being the most widely used by the clinicians. Its viscosity allows the application of increments, maintaining the shape when in place without flowing, enabling the use of a layering technique. The high-viscosity materials, namely condensable composites, were developed for use on posterior teeth for helping the restoration of the contact points with the adjacent tooth. Its viscosity helps to press the matrix during the application, although they were more difficult to handle. However, some techniques can allow the proper restoration of the proximal contacts without the need of such a high viscous materials. For this reason, those are currently seldom used on the daily dental practice. The composites may also vary according to the levels of translucency. A material is considered translucent when part of the light that hits its surface is transmitted through the material, allowing the underlying background to show through (. Fig. 14.3). It is possible to see through a translucent material, but the image is not clear. This characteristic is observed in variable levels on the dental enamel. The opposite property of translucency is opacity. A material is considered a totally opaque when the light that hits its surface is not capable to pass through it (. Fig. 14.3). Although the dentin is not completely opaque, it has a higher opacity level than the enamel. A material is called transparent when it allows almost total transmission of the light that hits its surface without being scattered, like a perfect glass, allowing to clearly see through it. A perfect transparency is not observed on the tooth enamel, even though they may be highly translucent. The translucency can also be described as partial opacity or a state between complete opacity and complete transparency. The degree of translucency is related to how deeply the light penetrates the tooth or restoration before it is reflected outward [31]. The enamel has high translucency, while the dentin has low translucency, even though it is not completely opaque.  

 

a

b

c

..      Fig. 14.2  Types of composites according to the viscosity. a Low; b medium; c high

Incident light

Incident light

Transmitted light

Incident light

Transmitted light

Absorbed light

Opacity

Translucency

..      Fig. 14.3  Differences among opacity, translucency, and transparency

Transparency

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>> A material is considered translucent when part of the light that hits its surface is transmitted through it. The opposite property is called opacity. The dental enamel is more translucent than the dentin, which is almost opaque. For the proper restoration of the tooth structure, the use of composites with translucency levels close to the natural dental tissues is necessary. The translucency of a composite is as relevant as its color, since it affects the final restoration appearance.

14

The overlapping of the enamel over the dentin on different thickness, according to the region of the tooth, is the responsible for the polychromatic effect observed on the natural teeth [3]. The thicker is the enamel or dentin layer, the less translucent it appears. The dentin is thicker and the enamel thinner  on the cervical region of the teeth, which gives a general opaquer aspect to this region. The shade is more saturated, with a greater inflence of the dentin color. On the middle third of the crown, the differences of thicknesses between enamel and dentin are less discrepant, making this region less saturated and more luminous. On the incisal third, the enamel is thicker and minimum or no dentin exist, prevailing the optical characteristics of the enamel [1]. The enamel translucency is not only due to its high degree of mineralization, but also because of its internal mineral organization of low refractive index, which allows the transmission of most of the incident light. The enamel prisms act similarly to the optical fibers. The light that enters the prisms is reflected by its crystals and remain on its interior, running through it. This effect is empowered by its radial orientation from the dentin-enamel junction (DEJ), directing the light to the center of the tooth, toward the dentin [1, 22]. For the proper restoration of the tooth structure, the use of composites with optical characteristics close to the natural tooth  is necessary to obtain excellence on the esthetic results. The dental composites are generally available with three levels of translucency. The high-translucency one,  namely incisal shade, are indicated for restorations of the enamel on the highly translucent incisal edges observed on some teeth. The composites with medium translucency, nemely enamel shade, are indicated for restorations of the enamel on most situations. They are also called by some manufacturers as universal or body shade composites. The lowtranslucency composites, nemely dentin shade, are used to restore the lost dentin tissue. They are referred by some manufacturers as opaque shade composites. The translucency of a composite is an essential optical property, as relevant as to color, since it affects the composite shade appearance. The knowledge about the translucency can help the selection of the most adequate composite and obtain the best esthetic results. The translucency of the human enamel increases with the years since its mineralization increases and the thickness decreases [2].

14.2 

Basic Concepts About Color

14.2.1 

Definitions

The color phenomenon is a psychophysical response to the physical interaction between the luminous energy and an object, associated with the subjective experience of an observer [26]. Visible light is a form of electromagnetic radiation, with wavelength range between 390 and 770 nm, which is detected by the light-sensitive photoreceptor cells of the human eyes. Each wavelength corresponds to a specific color. A light source can emit a single wavelength (monochromatic) or multiple wavelengths (polychromatic). When the light source is observed directly, the color that human vision detects is a result of the emitted wavelengths, which is the color of the light by itself. The more colors are emitted simultaneously by a light source, the more it comes close to white color. When the light hits an object, it can be transmitted through it, absorbed, or reflected, and this last one is responsible for the color perception that the humans have about the object. The more the incident light is absorbed by the object, the darker it is perceived by the observer. The more the polychromatic light is reflected by the object, the whiter it appears to the observer. Therefore, there is the color of the light, which corresponds to the wavelength emitted by the light source, and the color of the objects, which is the light reflected by an object. The color phenomenon is a psychophysical response to the physical interaction between the luminous energy and an object, associated with the subjective experience of an observer. The color of the light corresponds to the wavelength emitted by the light source, while the color of an object corresponds to the light reflected by it.

There are three factors that may affect the color perception, which are the light source, the object that is being seen, and the observer that is looking at the object [21]. The light source can emit luminous energy on a broad wavelength range, and it is characterized by the relative amount of energy for each wavelength on the visible spectrum. This way, the color perception is affected by the light that illuminates an object, because the different light sources have variable amounts of each wavelength of the visible light [21]. In relation to the object, its spectral reflectance or light transmission characterizes its color. For example, a red object has this color because it reflects the wavelength corresponding to the red color more than the green or blue ones (. Fig. 14.4a–e). In relation to the observer, the visual systems and the brain also affect the color perception. The primary colors are a biological concept based on the physiological response of the color vision system in the human eye to the light, and not a fundamental property of light. Essentially, the light is a continuous spectrum of  

471 Composite Restoration on Anterior Teeth

Incident light

a

Incident light

b Reflected light

Absorbed light c

d

e

..      Fig. 14.6  Value or the lightness of a color

..      Fig. 14.4  Color of the objects. a Every wavelength is absorbed resulting in the black color; b every wavelength is reflected, resulting in a white color; c–e prevalence reflection of a certain wavelength. (Adapted from Fraser and Banks [15])

..      Fig. 14.7  Chroma or hue strength

color is strong or vivid (. Fig.  14.7) [21]. The combination between the three-color dimensions gives the shade or tone of a color.  

..      Fig. 14.5  Hue or color name

wavelength, with an infinite number of colors. However, the retina of the human eye contains only three types of color receptors, called cone cells, having a trichromatic color vision. Each one of those cones is especially sensitive to certain wavelengths of light, which correspond to red, green, and blue colors. Those colors are considered the primary colors of the light source (RGB system  – red, green, and blue), because each of them can independently stimulate the cones, allowing a large range of color perception. The color can be described according to the Munsell color system, which is a three-dimensional model based on the premise that each color has three qualities or attributes: hue, value, and chroma. Hue is the actual color, for example, the red, green, and blue (. Fig. 14.5). Value indicates the lightness of a color, ranging from for pure black to pure white (. Fig. 14.6). The chroma is the intensity a color. When the chroma is low, the color is weak, while when it is high, the  

 

>> The three dimensions of color are hue (actual color), value (lightness), and chroma (intensity). The combination between them gives the shade or tone of a color.

14.2.2 

Optical Characteristics of Natural Teeth

Due to the large range of colors found on the natural teeth, it may be hard to choose the proper shade for a restorative material. Natural teeth are not monochromatic, and with a single composite shade, it can be impossible to match the polychromatism of teeth [3]. The natural polychromatism is the result of several shades found on enamel and dentin, influenced by the different thickness of those structures along the crown [3]. When analyzed separately, the enamel color varies from white to gray, while the dentin has variable amounts of yellow, orange, and red. The enamel is thicker on the incisal

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a

b

..      Fig. 14.8  Tooth with completely removed dentin. a View under reflected light; b view under transmitted light

edge and thinner in the cervical region. When the incisal edges are not worn, frequently have blue, violet, or gray tones, due to the enamel translucency and absence of the dentin. Therefore, a single monochromatic composite cannot match the complex color of the natural tooth [3]. The translucency of the composite varies according to the ratio between the smaller and larger filler particles. The perceived color of a composite restoration will also be influenced by the color of the background (preparation walls) [3]. >> A single monochromatic composite cannot match the complex color of the natural tooth.

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When the environmental light interacts with the tooth surface, the color perceived by the observer is a mixture of several wavelengths reflected by the tooth. As enamel is a translucent structure, when the light hits its surface, a certain part is reflected, another is absorbed, and the rest is transmitted through it, reaching the underlying dentin. From this light, a part is absorbed or transmitted, and the rest is reflected back to the enamel. The dentin is the main responsible for the basic hue of the tooth, presenting a chromaticity that varies from orange to yellow [1]. Therefore, the shade of the tooth structure perceived by the observer is a result of the light reflected by both dentin and enamel. The degree of translucency is related to how deep the light penetrated the tooth or the restorations before it is reflected. The normal is that light penetrates through enamel up to the dentin before it is reflected, which gives the lively and realistic appearance of the intact teeth. The little light penetration frequently results in the loss of the esthetic vitality for the restoration. This is a common phenomenon found when restoring teeth with veneers, a type of restoration that covers the entire labial tooth surface of very dark teeth (7 Chap. 17). Even though the opaque material is used to mask the background dark color, the loss of esthetic vitality usually is a result on little light penetration. The illusion of translucency may be created to increase the realism of the restoration. Color modifiers, also referred as tints, can be used to obtain the translucency appearance, darken the shiny stains, or characterize the restorations [31].  

The enamel has a peculiar characteristic called opalescence, due to its similar optical characteristics of the opal stone. When the enamel receives white light, which is a combination of different wavelengths, it is capable to reflect the shorter wavelengths, specially the blue, and transmit the longer wavelengths, such as the yellow and the red [1]. This is due to the mineral structure of the enamel, where the mineral crystals with 0.02–0.04 μm of thickness, smaller than some wavelengths of visible light, cause the selective reflection of the blue waves. The longer wavelengths, corresponding to the red and orange colors, do not deviate from its track and are completely transmitted through the enamel [1, 23]. Opalescence is a capacity of some materials to reflect the shorter wavelengths of light, mainly the blue, and transmit the longer wavelengths, such as the yellow and the red, like the opal stone.

The tooth has anisotropic optical properties, which means that its visual appearance changes depending on the angle of view or the angle of illumination. . Figure  14.8a, b shows a tooth that had its entire dentin removed illuminate from labial or lingual direction. When a white light source was positioned in front of the labial tooth surface, the light reflected by the enamel gave a bluish color to the structure. On the other hand, when the white light source was positioned behind of the tooth structure, hitting the lingual surface, the transmitted light gave an orange appearance to the tooth, due to the fact that enamel only allowed the transmission of longer wavelengths. However, in the daily life, where light source is always locate outside the mouth, the light that hits the labial surface is filtered by the enamel before reaching the dentin, which only receives the longer wavelengths. Mostly of this light is absorbed by the dentin, and a certain part is reflected, which returns through the enamel to the external surface. Thus, the light that observer sees when looking to a tooth is the addition of the blue light reflected by the enamel and the yellow and red wavelengths reflected by the dentin.  

473 Composite Restoration on Anterior Teeth

..      Fig. 14.9  Bluish aspect of the incisal edge due to the opalescent enamel (opalescent halo)

In relation to the general color of the tooth structure, in which the dentin tissue is present, the amount of blue light reflected is small in relation to the longer wavelengths. For this reason, the teeth are seen as a combination of reflected light colors, which is mainly a mixture of yellow and red in different ratios, resulting on an orange shade, together with a small amount of blue from the opalescence. The opalescence can be seen on the entire enamel, and it is not influenced by the thickness [1]. The enamel opalescence increases the lightness of the tooth and creates effects of optical depth and vitality [1]. However, when there is an evident translucent incisal edge, without underlying dentin, a preponderance of the shorter wave reflection occurs in this area, giving it a bluish appearance, known as opalescent halo (. Fig. 14.9). There are composites which are really opalescent and may be used to restore the lost enamel, and they should be applied over the entire labial tooth surface. However, when a opalescent composite is not available, the incisal edge with its characteristic appearance can also be recreated with a color modifier with bluish shade, covered by a highly translucent composite, even though this composite is not really opalescent by itself [1]. On the other hand, some people have the dentin on the tip of the developmental lobes of anterior teeth with intense white opaque shade. This does the dentin in this area to have higher light reflection capacity than the rest of the tooth. Therefore, in this specific region, the reflection of yellow and red light which crossed the enamel and hit the dentin will be higher, resulting in an orange appearance  to the area (. Fig.  14.10a–d). This phenomenon is called counter-­ opalescence. In . Fig.  14.11, clinical aspect of the counter-­ opalescence can be observed. In . Fig. 14.12a–c, the counter-opalescence phenomenon can be reproduced with some naturally opalescent composites, changing the background color. To obtain this effect during the restorative procedure on anterior teeth, the tip of the dentin lobes can be restored with wither and opaque composite than the rest of the dentin. Then, it is covered with a highly translucent layer of naturally opalescent composite. The light transmitted and filtered through the enamel shade composite layer is reflected by the white dentin composite on  

 

 

 

the tip of the lobes, creating the orange appearance on this area [1]. When truly opalescent composites are not available, the effect can be recreated with orange color modifiers, creating an illusion of counter-opalescence [1]. The way the light waves pass through the composite is different from the way they interact with the natural crystalline mineral tooth structure. When the light hit the filler particles of different sizes and shapes of a composite, its scattering happens on an uneven way. This creates on a higher light refractive index than enamel. Therefore, it is difficult to guess the ideal thickness of the enamel shade composite layer  necessary on the labial surface of a tooth to be restored, without compromising the final translucency and lightness [1]. The thickness of the enamel and dentin shade layers of a composite is one of the main factors that modulate the final esthetic result. Very thin enamel shade layer can allow us to look through the dentin too much, resulting in restorations more saturated (higher chroma) and with smaller lightness (smaller value). On the other hand, a very thick enamel shade layer results in a monochromatic and grayish restoration. However, the restoration of lost enamel with a composite, following to the natural enamel thickness, results in an optical behavior opposite to the natural tooth when enamel illuminated. While for the natural enamel the increase of its thickness produces the increase of the lightness, thicker composite enamel shade layers reduce the final lightness. When the enamel is reconstructed with anatomic thickness, the higher refractive index of the composite results on a low lightness restoration, with grayish appearance [1]. To overcome this difference, the enamel shade composite layer must have about one-third of natural enamel thickness, increasing the thickness of the dentin shade composite, allowing to ­recreate the enamel lightness without compromising its translucency [1]. >> The thickness of the enamel and dentin shade layers of a composite is one of the main factors that modulate the final esthetic result of a restoration.

Another optical property of the tooth structure which influences the restorative procedure is the fluorescence. It is a phenomenon of spontaneous emission of radiation by some atoms and molecules inside the tooth structure composition, being considered a kind of photoluminescence. The photoluminescence is the light emission from any form of matter after the absorption of photons. It occurs when an atom receives stimulation by light waves of a specific wavelength, and this energy is absorbed. The electrons change the atomic energy level from a ground energy state to a more external level, entering in an excited energy state. This excited state is unstable, and the electrons spontaneously come back to a ground energy state, releasing the difference in energy between the two states as a photon of light, generally with a wavelength different from the one that first exited the atoms. There are two types of photoluminescence, named phosphorescence and fluorescence. The phosphorescence naturally occurs in some mineral when the material is stimulated by a light source. The energy is absorbed by the atoms, and a phosphorescent light is generated and slowly released, even

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c

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Opalescence

b

Opalescence

..      Fig. 14.10  Opalescence and counter-opalescence. a Whitish dentin on the tip of the developmental lobes; b incidence of white light on three different areas of the labial surface (1, incisal edge without dentin; 2, tip of the whitish dentin lobules; 3, rest of the tooth structure); c reflection of the blue light (shorter waves) by the enamel

Opalescence

d

on the three areas and transmission of the orange light (longer waves) toward the dentin; d complete transmission of the yellow light through the incisal edge without dentin (1) and reflection of the light by dentin, more intense on the tip of the whitish lobules (2 – counter-opalescence) and less intense on the rest of the structure (3)

a

..      Fig. 14.11  Clinical aspect of the counter-opalescence showing orange areas on the incisal third of the labial surface, on both central incisors

b

c

..      Fig. 14.12  Composite slabs placed over a white and black background, showing the counter-opalescence over the white background. a, c opalescent composites – over the white background, they seem to be more yellow than over the black background; b non-opalescent composite (the background has no inflence on its color)

475 Composite Restoration on Anterior Teeth

a

b

..      Fig. 14.13  Patient with restoration with nonfluorescent materials. a under environmental light; b under ultraviolet light

after the end of the stimulation, making the object remains glowing for a certain time. In case of the fluorescence, after the energy from a light source is absorbed, the fluorescence light generated is only emitted, while the object is still stimulated by the light source.

nonfluorescent composites. Therefore, it is a surface phenomenon [1]. People with composite restoration made of nonfluorescent composites have its esthetics impaired on the places illuminated with black light, because the restorations become evident as dark areas (. Fig.  14.13a, b). However, in an attempt to simulate the dental fluorescence, some manufacturers to produced composites even more fluorescent that the natural teeth, resulting in the opposite effect. The restorations done with those materials appear brighter than the teeth  under UV. This way is important that the composite has fluorescence, but its intensity must be similar to the natural tooth structure (. Fig. 14.14a, b). The DEJ is a thin partially mineralized layer, formed mainly by collagen fibers. It works absorbing the forces applied over the enamel, transmitting it to the dentin, playing also an important role in the way the light is dispersed and transmitted inside the tooth. The DEJ is a highly translucent structure, of low refractive index, allowing all light that goes through the enamel reaches the dentin. This contributes to the feeling of depth and vitality of the natural teeth, and it is important to the process of internal light diffusion and control of lightness. The reproduction of the DEJ on direct restorations can be made with materials and techniques that allow the same light interaction and optical results. A thin layer of a flowable composite specially developed for this purpose can be used (Glass Connector, Micerium), applied on the labial surface in a thin layer between the dentin shade, composite previously light-cured, and the enamel shade layer, increasing the light diffusion and the lightness of the restoration [1]. The color of the natural teeth is something dynamic. It is influenced by the incident light, topographical anatomy, and hydration condition of the tooth structure, besides the individual optical properties of enamel and dentin. Therefore, it is not enough to understand the concept of the three-color dimensions, but also its interaction with the translucency, opalescence, counter-opalescence, fluorescence, and superficial enamel texture [1]. An important point when analyzing tooth color is the fact that it is a polychromatic structure. As the color observed is a result from the interaction of the light  

Fluorescence is a phenomenon of spontaneous emission of radiation by some atoms and molecules, consisting on absorption of light in a certain wavelength (generally UV) and emission in another, generally visible light.

 

A specific type of fluorescence can be noticed on the human teeth after they are irradiated with ultraviolet light. This wavelength is part of white light emitted by the sun, but it is more evident on places illuminated with “black light,” generated by light bulbs that produce mainly ultraviolet light, being used in nightclubs, theaters, stage, and as special effects. This ultraviolet wavelength is almost invisible to bare eye. However, when absorbed by the tooth structure, results in the emission of visible light of whitish-blue color, which does the tooth, appear brighter. Even though enamel and dentin are fluorescent, this property is three times bigger on the dentin than on the enamel. The enamel seems to act as a filter, attenuating the intense fluorescent emissions that come from the dentin [1, 43]. It is the result of the excitation of some organic molecules specially located in the dentin, such as the pyridinoline, thymine, and tryptophan. The fluorescence turns the natural teeth whiter and brighter under daylight, seeming as they are internally illuminated. Differently from natural teeth in which the dentin and the enamel contribute to the final fluorescence emission, on the composite restorations, the main responsible for this effect is the superficial layer, despite the underlying layers were or not restored with a fluorescent composite. It means that a superficial layer with a nonfluorescent composite blocks the emission of an underlying layer of fluorescent material; and a superficial layer of fluorescent composite gives fluorescence to the restoration when applied over

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a

b

..      Fig. 14.14  Comparison between the fluorescence of several composites (specimens in disc shape) and a human tooth fragment. a Aspect under day light; b aspect under ultraviolet light (“black light”)

a

b

Cervical third

Medium third Incisal third

14 ..      Fig. 14.15  a Transverse cut of an upper central incisor crown showing the enamel and dentin thickness on each third; b clinical aspect of the teeth with noticeable shade differences from cervical to the incisal area

with the enamel and dentin, the amount of each tissue and its individual chromatic characteristics will result on a specific shade. In fact, the tooth color is mainly determined by the dentin and modified by the enamel. >> The color of the natural teeth is influenced by the incident light, topographical anatomy, and hydration condition of the tooth structure, besides the individual optical properties of enamel and dentin. Therefore, it is not enough to understand the concept of the three-color dimensions but also its interaction with the translucency, opalescence, counter-opalescence, fluorescence, and superficial enamel texture. . Figure  14.15a, b shows that enamel and dentin thickness vary according to the region on the crown, resulting on different shades depending on the location. On the incisal third of the crow, there is more enamel than dentin, while toward the cervical third, the amount of dentin increases and of enamel decreases, resulting on a darker shade [31]. The dentin chroma increases from incisal edge toward the cervical  

area and from DEJ toward the pulp [1]. Therefore, the incisal third has a higher value and translucency than the cervical third, while the middle third is a mixture of the incisal and cervical shades [31]. The use of several composite shades may be required to esthetically restore the teeth. The dentin shade must be taken looking directly to the dentin, whenever it is exposed, or in the cervical region of the tooth, where the enamel is thinner and more translucent, which allows the best comparison with the underlying dentin chroma. The enamel shade of a composite can be better taken on the middle third of the tooth to be restored, where the thickness of the enamel is larger  than in cervical area and there is less influence of the chromaticity promoted by the dentin. Even though the enamel translucency can be evaluated on the incisal third, the absence of the underlying dentin structure and the presence on the dark background of the mouth on this region, may confuse the clinician and lead to the selection of excessively translucent composite [1]. Although the teeth are polychromatic, many may present a single shade from cervical margin up to the incisal edge [3].

477 Composite Restoration on Anterior Teeth

a

b

c

d

..      Fig. 14.16  Use of the VITA Classical shade guide. It can be noticed variation on the chroma and value for each hue. a VITA Classical shade guide; b selection of hue (A, B or C); c simultaneous selection of the chroma and the value (1, 2 or 3); d selected shade (A1)

14.2.3 

Shade Determination

(. Fig. 14.16b). They are placed near the tooth, choosing the one that most match the tooth color. Then the tabs of the chosen hue, with different chromas/values (1, 2, 3, 3.5, 4) are placed close to the tooth, and the one that best match is selected (. Fig. 14.16c, d). To improve accuracy of the shade selection process, the VITA Company developed a new shade guide, in which each color dimension is selected separately, namely VITA Toothguide 3D-MASTER.  It uses a dichotomic decision  method ( Yes/No or Better/Worse) (. Fig.  14.17a–i). First of all, the value is determined by selecting the one of the lightness groups (0, 1, 2, 3, 4, and 5). For that, the upper shade tabs are used (0M1, 1M1, 2M1, 3M1, 4M1, and 5M1) by making a simple yes or no decision if they match the tooth (. Fig.  14.17b, c). The selection should be started with the darkest group first. The second step consists on determining the chroma. On the basis of the determined value level, the middle hue group (M) is chosen, spreading the tabs out like a fan. Then, one of the three shade samples (1, 2, or 3) is selected (. Fig. 14.17d, e). Finally, the hue is selected looking if the natural tooth is more reddish (R) or more yellowish (L) as compared to the shade sample selected (. Fig. 14.17f–h). Despite the efforts of the manufacturers to match the color of its direct restorative materials to the VITA shade guide, this last one is made of ceramic, with huge differences  

When performing a composite restoration, the first step is to select a restorative material with similar shade to the remaining tooth structure and/or the adjacent teeth. The teeth shades were classified by the restorative materials manufacturers on specific categories, which represent the most common teeth colors. Different types of shade guides were produced, related to the shades of their respective products. At the beginning, each composite brand had its own shade guide, which made more difficult for the dentists to move to another brand, because they have to learn how to work and recognize the new shades. However, with the time, most of the dental materials manufactures started to match the shade of their product with the VITA Classical shade guide (VITA, Bad Säckingen, Germany), developed for VITA ceramics. It presents four shade families that differ according to the hue. The family A varies from reddish to brownish, while the B varies from reddish to yellow. The C family has grayish shades due to the smaller chroma. The D family has the reddish-gray shades. The shades on each family vary simultaneously according to the chroma and value, being classified by the numbers 1, 2, 3, 3.5, or 4 (. Fig. 14.16a). To use the VITA Classical shade guide, first the hue should be selected (A, B, C or D). For that, shade tabs of different hues but with the same chroma/value are selected  

 

 

 

 

 

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..      Fig. 14.17  Use of the VITA Toothguide 3D-MASTER. a Shade guide; b, c selection of the value (group); d, e selection of chroma; f, g selection of hue; h selected shade; i black and white image to confirm the value of the shade selected

in relation to composites, such as the presence of an organic matrix. Therefore, this reproduction can never be exact [7]. The shade guides should rather  be made with the same

c­ omposite to be used for the restoration. In addition, they should be kept hydrated by immersion in a water container, because hydrated composites are always darker [1–3].

479 Composite Restoration on Anterior Teeth

a

b

..      Fig. 14.18 Metamerism. a Shade determination of a natural tooth under environmental daylight; b natural tooth and shade tab under dental light with halogen lamp

In order  to perform the shade determination using shade guides, some basic principles must be followed. The first one is to hold it at least at one arm’s length to the patient’s mouth. To look the shade guide too close adversely affect the shade selection. The teeth should be viewed along a line of sight perpendicular to the tooth surface. The shade tab should be placed parallel to the tooth being matched and in the same plane. The shade determination must be performed before the rubber dam isolation, with the teeth clean and hydrated. It must be done before the teeth undergoes any long drying period, because the dehydration makes the teeth lighter, as the result of the translucency reduction [31]. This way, if the shade was correctly selected before the rubber dam isolation, immediately after its removal, the restoration will appear darker than the dehydrated tooth remaining. If the restoration shade is similar to the dehydrated tooth remaining, it is probably that the shade selection was incorrect and with the hydration, after the contact with saliva, it will appear lighter [3]. The complete hydration of the teeth may take several hours. Another point is the color of the office room where the shade determination is performed. The walls and other object in dental office reflect the light in the wavelength corresponding to its color. This will influence the color of the other objects observed in the same room, such as the teeth. For this reason, the walls, dental treatment unit and furniture must have neutral colors. It is also important to ask the patients to remove the red lipstick. If the patient is wearing colorful clothes, it is advisable to cover them with a patient bib with a neutral color, such as white or gray. The observed color of objects depends on the characteristics of incident light. If an object is illuminated with white light, it will have a certain color, determined by its interaction with the different wavelengths of this polychromatic illuminant. This same object, when illuminated with another light source which has the predominance of different wavelengths, its final color can be different. This phenomenon is called metamerism [31]. Each material interacts in a specific way with the incident light from each light source. Therefore, the color of objects with different compositions can change when the illumination is modified. Two objects may have the same

color under a certain light source, but have very different color under other illuminations. In the dental office, when the teeth of a patient and a selected shade guide tab matching its color are illuminated under natural sunlight they can match perfectly [3]. However, when the same teeth and shade tab are illuminated by an incandescent light bulb, such as the one in most of the overhead chair lights, the teeth and the shade tab atoms will not interact on the same way with the incident light, because they are made by different materials. This will result on different shades from those observed under the natural light, making the initial shade determination to appear incorrect (. Fig.  14.18a, b). Therefore, the shade taking must be performed under the natural light or under artificial light that simulates the daylight (fluorescent light bulb), because this is the illumination of the environment which they are exposed on most of their daily lives [31]. Another important point during the shade determination is the fact that the dentist should not keep looking to the teeth and shade guide for a long time. That must be done very quickly. After about 30 s, the photoreceptor cells of retina become saturated by the wavelengths reflected from the teeth, creating a visual fatigue. That adversely affect the distinction of small differences on the shade from yellow to orange range  observed on the tooth structure [31]. In case that happened, it is convenient that the clinician relaxes the eyes looking for a few seconds at an object of complementary colors in relation to the teeth colors, such as the blue, violet, or green [27, 31]. Blue is the complementary color of orange, while violet is of yellow and green of red [31, 40]. When looking at objects of complementary colors, the photoreceptor cells of the eyes are recovered, increasing the sensitivity to notice the small variations in yellow and orange [31]. Then, the dentist can come back to the shade determination procedure. Some clinicians ask the aid of the dental assistant as a second opinion to help the shade match [31]. The shade selected must be registered on the dental records of the patient, as well as the composite brand that will be used [31]. If dental bleaching is planned on the patient’s treatment plan, it must be performed before any restorative procedure with composites [31].  

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a

b

c

d

..      Fig. 14.19  Digital color image converted to black and white a, c color images; b, d the same images in black and white to evaluate the value match between the shade guide and tooth

14

a

b

..      Fig. 14.20  a VITA Easyshade spectrophotometer; b device being used

To evaluate the color match of the shade guide, besides other characteristics of the tooth, a photographic camera can be used. The glossy areas can be eliminated through polarizing filters, allowing observing more details of the inner dentin, clearly identifying the translucent areas of enamel [2]. A digital photography of the shade tab and the teeth can help to evaluate if the matching is correct. Using a photo editing software, the image can be turned black and white, helping to evaluate if the

value of the shade tab matches the tooth (. Fig.  14.19a–d). Another possibility for shade determination is the use of intraoral spectrophotometers. They have the advantage of making an objective color reading, without human interference, offering shade results according to the VITA Classical and 3D-MASTER shade guides (. Fig. 14.20a, b). After the shade determination, a direct matching confirmation can be performed using the selected restorative  

 

481 Composite Restoration on Anterior Teeth

a

b

..      Fig. 14.21  a Composite portions without polymerization (to the left) and polymerized (to the right). a Palfique Estelite Sigma (Tokuyama); b Z350 (3M/ESPE)

material. It is well-known that composites generally do not perfectly reproduce the shade guides. This way, a small portion of this material can be applied over the tooth to be restored and light-cured, without previous adhesive application, verifying if the selected shade was correct [31]. After that, the composite can be easily removed with an exploratory probe [31]. It is important to light-cure the materials because the composite shade slightly changes after curing (. Fig. 14.21a, b) [2, 27]. A good polymerization for the complete elimination of the camphorquinone residues, responsible for this color changes, is necessary. On the case of the teeth with several chromatic nuances, it is possible to make a restoration mock-up, building the entire restoration with the combination of shades and opacities selected for the composites, without adhesive application, evaluating if the final shade matching was adequate [1–3, 27]. During the shade determination procedure, it must be evaluated how translucent is the tooth enamel, verifying if it will be required the use of a highly translucent composite during the restoration. However, on older patients, its use is generally not necessary [3]. Even though the shade determination is a very important step to obtain a good esthetic for a restoration, this procedure by itself does not guarantee that a perfect result will be obtained. The final shade of the restoration is the result of the interaction between the color of the background, if there is some remaining tooth structure, the color of the dentin shade composite, and the color and translucency of the enamel shade composite applied over it. . Figure 14.22a–d shows a shade guide simulation made with actual composite, which allows to superimpose enamel shade veneers over the dentin shade cores, being possible the color analysis of various combinations. In . Fig.  14.22a, b, are shown  different dentin shade cores covered by the same enamel shade composite  venners, showing a different final shade for each combination. In . Fig.  14.22c, d, are  shown the same dentin shade cores covered by different enamel shade composites  venners, creating different final shade results.  

 

 

 

Some manufactures produce actual shade guides following the superimposition concept presented, in which are possible to check the combination of enamel and dentin shade tabs. An example is the Coltene Company, which named this method as “nesting” shade selection (. Fig.  14.23a–c) because the enamel shade tab has a veneer shape and nestle over the dentin shade tab with a core shape. Using this shade guide is necessary to place some water or glycerol between the veneer and the core, creating an optical contact. That avoids possible effects of light refraction at the transition and reveals the final color, allowing the comparison with the tooth structure. If there is no match, a different enamel or dentin shade can be selected. The use of the same colors for enamel and dentin shades, e.g., dentin A2 and enamel A2, results in the same final color for the restoration, in this case, A2. However, as shown in . Fig.  14.23a–c, when associating the dentin A1 with the enamel A2, or the dentin A3.5 with the enamel A2, the final color obtained will be intermediate between the original colors. This must be considered when it is planned to combine different colors for the enamel and dentin shades in a certain restoration. The tooth color observed in the clinical exam must match the resulting color of the shade’s combination.  

 

Tip

In order to perform a good shade determination, the following principles should be followed: 55 The dentin shade selection should be done taking the shade tab close to some exposed dentin area, whenever it is possible, or close to the cervical region of the tooth. 55 The enamel shade of a composite can be better taken on the middle third of the tooth to be restored. 55 The shade guides should be made with the same composite to be used for the restoration and kept hydrated by immersion in a water container. 55 The shade guide should be hold it at least one arm’s length far from the patient’s mouth.

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55 T he teeth should be viewed along a line of sight perpendicular to the tooth surface. 55 The shade tab should be placed parallel to the tooth being matched and in the same plane. 55 The shade determination must be performed before the rubber dam isolation. 55 The walls and furniture of the dental office must have neutral colors and the patient is asked to remove the red lipstick. 55 If the patient is wearing colorful clothes, it is advisable to cover them with a bib with a neutral color, such as white or gray. 55 Shade taking must be performed quickly, under the natural light or under artificial light that simulates the daylight. 55 When taking too much time looking to the tooth to choose the right shade, it is convenient that the clinician relaxes the eyes looking to an object blue, violet, or green, for a few seconds, to recover the eyes from fatigue. 55 To confirm the shade selection, small amounts of composite can be applied and cured over the tooth without adhesive, and mock-up restoration can be performed.

14.3 

Selection of Composite Resin

After the shade determination is finished, the choice of the kind of composite to be used on that particular restoration must to be performed. The first point to be evaluated is the stress level that the future restoration will undergo. In places where the restorations will not receive the direct occlusal loads, such as on Class V and Class III preparations without the involvement of the lingual surface, restorative materials with inferior mechanical properties can be used, such as the microfilled composites. However, if the restoration involves the lingual surface, on a contact area or disocclusion guide, or even on restorations of the incisal edge, it is necessary to use a stronger restorative material, such as the hybrid, microhybrid, nanohybrid, or purely nanofilled composites. Another point is the necessity of obtaining a high polishing of the restoration surface. Mainly for those in the cervical regions, the restorative material must be polished until reaching a surface roughness similar to the natural enamel, reducing biofilm deposition ang gingival inflammation. For that, the microfilled, nanohybrid, purely nanofilled, or even microhybrid composites can be preferably used. The macrofilled and hybrid composites should be avoided.

a

b

c

d

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..      Fig. 14.22  Shade guide simulation allowing superimposition of enamel shade veneers over dentin shade cores. a, b Same enamel shade over different dentin shades; c, d different enamel shades over the same dentin shade

483 Composite Restoration on Anterior Teeth

a

b

c

..      Fig. 14.23  a Nesting shade guide of the Brilliant composite (Coltene) showing dentin shades on the left and enamel shades on the right; b, c combination of the same type of enamel shade (A2) with different dentin shades (A1, A2, and A3.5) resulting on several final tones

Finally, an important point is the esthetic results provided by the material, which besides a proper color match, must have translucency and gloss similar to the tooth structure. It can be noticed that there are large differences among the composites provided by different manufacturers, mainly in relation to the optical properties. This way, even if a correct shade determination has been performed, the final esthetic outcome may not be adequate. In addition, certain brands may not have a composite that match some specific patient’s tooth being restored. The clinician must become familiar with the differences between the products to be able to choose best alternative for each patient. However, the composites that allow a better polishing have a higher chance to produce an adequate result. The modern materials such as the microhybrid, nanohybrid, and nanofilled composites may allow these required results. 14.4 

I ndications of Composites on Anterior Teeth

The composite restorations on anterior are indicated on teeth that suffered carious or non-carious lesions, fractures, or abnormal formation of the enamel. They can also be indicated on teeth that require modifications due to its shape, such as in the case of diastemas or peg-shaped teeth, or due to its wrong position, such as rotated or inclined teeth. The composite also can be applied on cases of teeth with color alteration that could not be properly bleached, when labial surface can be completely covered by the restorative material to improve the esthetics of the smile (see 7 Chap. 17). As can be observed for all restorative materials, the composites also do not show a good behavior in patients with poor oral hygiene. The acids produced by the bacteria attack the organic composite matrix, resulting in the softening of the material, increasing its wear and premature staining. Patients with parafunctional activities such as bruxism, clenching, nail biting, and pencil chewing must be alerted about the possibility of fractures or displacement of the restoration. The excessive and cyclic  loads applied over the  

restored teeth can generate fatigue of the restorative material, resulting in fracture and/or displacement of the restoration. The parafunctional habits must be treated, and, in some cases, the use of an occlusal splint for an indefinite period of time is necessary to protect the teeth and the restoration. The smoking habit also causes premature staining of the restorations, which will need to be often repolished to maintain the good esthetic result. In the same way, deleterious eating habits such as high intake of acidic food and drinks, as well as food colorings agents  and alcohollic beverages, will also result in the degradation of the organic matrix of the composite. Even though most composites allow a good polishing of its surface, tooth preparations with cavosurface margins inside the crevice represent a great challenge. First of all, there is a difficulty to obtain proper isolation of the operating field, which may result in the contamination of the preparation with the fluid from the gingival sulcus, blood, or saliva. It is known that the adhesive procedure can only be performed in a completely clean and dry preparation; otherwise, the bonding to the tooth structure will fail [31]. In addition, in some cases, there is no enamel on the gingival cavosurface angle. As the bonding to the dentin margin is more difficult and less predictable than to enamel, more marginal gaps can occur, increasing the microleakage and the probability of secondary caries. Other than that, the difficulty to proper finish and polish the restoration margin may result in the presence of overhangs or rough surfaces that increase the biofilm deposition and cause constant gingival inflammation. The composite restorations are also indicated as part of the treatment for the non-carious lesions of erosive tooth wear, abrasion, or abfraction. The restorations are indicated when the lesion is active and no success was obtained on the attempts to interrupt its progression; the structural integrity of tooth is threatened or there is a risk of pulpal exposure; the structural defect is unacceptable on the esthetic point of view; the dentin is hypersensitive and the sensitivity was not reduced with the non-restorative treatment; or there are carious lesions associated [3]. Besides several other advantages, the restorations decrease the rate of progression or even arrest the structural loss process.

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a

b

c

..      Fig. 14.24  a, b, c Pictures taken from different angles showing several topographical details of the surface that should be reproduced, such as sulcus and lobes

a

b

..      Fig. 14.25  a, b Translucent incisal edge and opaque halo (arrows)

14.5 

Esthetic Analysis of Anterior Teeth

translucent incisal edge that must be reproduced in the composite restoration (. Fig.  14.25a, b). An opaque halo can also be observed, which is an optical phenomenon produced by the changes in the enamel prism direction. The halo thickness, contour, and proximal extensions can vary from tooth to tooth [1]. The opaque halo effect is produced by the total reflection of the light, because angle of incidence is greater than the limiting angle of the enamel, that is, 37° [2]. When the teeth are hydrated, the light refraction is changed in relation to when they are dried, reducing the thickness of the opaque halo and increasing the enamel translucency [1].  

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In 7 Chap. 1, several factors related with the smile esthetics were discussed, based on the relations among the group of teeth forming the dental arch and the positions of the lips and gingiva. In the following sentences, aspects related to tooth units alone will be discussed, which is important for the proper restoration of the lost tooth structure. According to Baratieri et al. [2], the hands are capable to reproduce just what the eyes were able to see. In other words, when trying to restore a tooth, it is important that the dentist is capable to identify their multiple and complex anatomical details. Therefore, a comprehensive  esthetic analysis of the damaged tooth must be performed before performing a restoration.  The contralateral tooth can  be used as a reference  to guide the restoration of the lost tooth structure. The first strategy for that is to observe the tooth from several angles, allowing that all topographical details can be noticed (. Fig. 14.24a–c). The restored areas on the teeth must reflect the light in a similar manner to the intact adjacent surface [31].  

 

14.5.2 

Morphology of the Incisal Edge

The newly erupted anterior teeth have an irregular contour of the incisal edge due to the presence of mamelons, which are three-rounded protuberances formed by the developmental lobes, separated by grooves, which can be compared with the shape of the fleur-de-lis (. Fig. 14.26a, b). On patients with a very translucent incisal edge, the contour of the dentin mamelons can be observed through the enamel (. Fig. 14.27a, b). To improve its visualization, a digital photograph of the anterior teeth can be obtained and manipulated in image editing software, increasing its saturation (. Fig.  14.27b). . Figures  14.28a–d, 14.29a–d, and 14.30a–d show extracted  

14.5.1 

Enamel Translucency

The translucency of the dental enamel must be evaluated before performing a composite restoration. The anterior teeth of many patients, mainly the younger ones, present a

 

 

 

485 Composite Restoration on Anterior Teeth

a

b

..      Fig. 14.26  a, b Incisal edge contour with shape of the fleur-de-lis (arrows)

a

b

..      Fig. 14.27  a Demarcation of the lobes seen through the translucent incisal edge; b to increase the saturation of a digital picture allows better observation of the dentin lobes

a

b

..      Fig. 14.28  Outer and inner morphology of an upper central incisor. a, c With enamel; b, d enamel completely dissolved by immersion in the acid solution, allowing dentin visualization

intact upper anterior teeth before and after its complete demineralization, through the immersion of an acidic solution for some days, remaining only its collagenous dentin

structure. With this technique, the outer morphology of the enamel and the inner morphology of the dentin can be compared, allowing a direct view of the dentin lobes.

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c

d

..      Fig. 14.28 (continued)

14

a

b

c

d

..      Fig. 14.29  Outer and inner morphology of an upper lateral incisor. a, c With enamel; b, d enamel completely dissolved by immersion in acid solution, allowing dentin visualization

14.5.3 

Surface Texture

The surface texture of natural teeth is composite by macroand microtexture. The macrotextures are represented by the depressions and elevations found on the enamel surface. On the labial surface of an upper central incisor, the macrotexture is generally characterized of three vertical lobes separated by two grooves (. Fig. 14.31a, b). The macrotexture is  

responsible for the areas of light reflection creating the relief sensation of the surface. The visual impact and the dimension perception of width and length come from the interaction of the light with those areas, which is reflected in the more elevated areas on the surface topography [1]. The microtexture is created by the perikymata, which are incremental growth lines in youthful teeth that appear on the surface of enamel as a series of transverse parallel grooves,

487 Composite Restoration on Anterior Teeth

a

b

c

d

..      Fig. 14.30  Outer and inner morphology of an upper canine. a, c With enamel; b, d enamel completely dissolved by immersion in the acid solution, allowing dentin visualization

a

b

..      Fig. 14.31  a, b Macrotexture. Demarcation of grooves between the developmental lobes on the labial surface (lines)

affecting the light reflection and the lightness of a tooth, creating areas of light and shadows that give movement sensation. On young patients, the perikymata create a very irregular surface. However, due to the enamel wear with the years, the tooth surface becomes smoother, and the perikymata disappear (. Fig. 14.32a, b). For a better observation of the surface details during the clinical exam, it is recommended to place the index finger on the cervical region of the  

teeth, creating shadows that better reveals the morphology [2]. To obtain good esthetic results with composite restorations, it is essential that the texture details are properly reproduced. When the macro- and microtexture are recreated, with glossy and light-reflecting areas, the lightness can be manipulated and indirectly decrease or increase the translucency of the restoration. A rough and irregular surface, rich in

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a

b

..      Fig. 14.32 Microtexture. a Young patient’s teeth showing the transversal lines corresponding to the perikymata; b middle-aged adult patient showing smooth labial surfaces

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microtexture, reduces the tooth lightness but increases the translucency, reducing the gloss and interfering with the chromatic perception. A well-polished surface becomes less translucent, reflects more light, and increases the lightness [1]. The understanding about the relation between the macro- and microtextures over the reflection and dispersion of the light, as well as its influence on the lightness and translucency of the restoration, is essential when performing the finishing and polishing procedures [1]. During the esthetic analysis of the tooth to be restored and the neighbor teeth, its shape and dimensions must be analyzed, as will be mentioned further on, as well as the size and shape of the incisal embrasures, according to what was described in 7 Chap. 1 (. Fig. 1.11a–d) [3].  

14.5.4 

 

Dental Dimensions and Proportions

The dental dimensions and clinical crown width-to-length ratios, part of what is called microesthetics, have a large influence on the esthetic of the smile. The presence of disproportion on dimensions may be corrected in some cases through a restorative treatment or periodontal surgery. The length of the clinical crown on anterior teeth is the distance between the incisal edge and the gingival margin. For some individuals, the teeth may clinically seem to be shorter than the anatomical crowns really are, because the gingival margin is more coronal to the cementoenamel junction (CEJ) than the ideal, due to an altered passive eruption [14]. On older adults, it is expected the abrasion on the incisal edges, which also causes the shortening of the clinical crown. In some cases, the reduction of the teeth length due to the wear is compensated by the gingival recession due to a gradual reduction of the periodontal support [14]. Most of the studies about the dental proportion concluded that the width of esthetically harmonic upper central incisor corresponds to about 80% of its length, with variations between 75% and 85% (. Fig. 14.33a–f) [14, 37]. This width-to-length ratio distinguishes its characteristic shape.  

The length of the upper central incisor range between 10.4 and 11.3 mm and the width between 8.3 and 9.3 mm. Men, generally, have incisors with a larger width than women, while women generally have a clinical crowns with a shorter length than men [14, 37]. The central incisors present a dominance on the final aspect of the smile. A key point for esthetic smile is the symmetry of those teeth that generally present the same shape and size, as a specular image, even though in nature it is hard to find those teeth perfectly identical, which occurs in only 14% of the cases. The asymmetry is common both on the width and on the length, although discreet differences are not noticed. However, discrepancies on the width and length larger than 0.3 mm will be easily noticed by the observers and may be convenient some kind of correction [14]. The dimensions of the upper incisors also have a relation with the dimensions of the lower incisors. The width of the upper central incisor corresponds to approximately the width of the lower central incisor added to half the width of the lower lateral incisor [25]. >> The width of esthetically harmonic upper central incisor corresponds to about 80% of its length, with variations between 75% and 85%.

The upper lateral incisors have the shape and contour similar to the central incisors, although with a smaller width of about 2–3  mm [37]. The length of the crown is about 1–1.5  mm shorter (approximately 20%) than the central incisors. The differences of size and position between the lateral incisors may be very large, not only from one person to another but also inside the same mouth. The variations found in size of those teeth allow that, if necessary, small changes in the length and width can be performed in one or both teeth, because it will hardly be noticed by the observers, since the small differences are frequent on nature [14, 35]. On the other hand, the presence of diastema may significantly adversely affect the esthetics of the smile, requiring its closing by means of an adhesive restoration, as will be discussed further in this chapter.

489 Composite Restoration on Anterior Teeth

a

b

c

d

e

f

..      Fig. 14.33  Width-to-length ratio (R) of the central incisors (W-width, L-length). a, b Teeth with normal proportions; c, d excessively long teeth; e, f excessively short teeth

Tip

The variations found in size of lateral incisor allow that small changes, in the length and width, can be performed in one or both teeth using composite, because it will hardly be noticed by the observers, since the small differences are frequent on nature.

The upper canines are about 1–1.5 mm smaller in width than the central incisors, even though having a similar length,

with a variation of only 0.5 mm [37]. They also have variations in the morphology. In some people, they have a sinuous shape, with a sharp point that gives them a vigorous appearance, while sometimes they are particularly round and delicate. Their gingival zenith and the tips of the cusp are generally not perfectly aligned to the horizontal plane. Its faciolingual position is also asymmetric, and it may cause disharmony on the progression of the inter-incisor angle or incisal embrasures [14]. The analysis of the width-to-length ratio of the anterior teeth may be performed directly in the mouth, using a bow

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compass with two needle points positioned on the teeth, which is then placed over a ruler to measure the distances in millimeters, or using calipers. The mathematical calculations may be performed obtaining the proportions. However, this process takes time and is preferred to be performed on a study model. An alternative to simplify this procedure is to use the proportion gauge developed by the professor Stephen J. Chu, marketed by the name of Chu’s Aesthetic Gauge (Hu-­ Friedy) (. Fig.  14.34a). The complete set of instruments includes a proportion gauge to measure the proportions of  

the crown; a crown lengthening gauge to evaluate the need for lengthening of the clinical crowns, due to discrepancies of the gingival margin position by means of periodontal surgery; and a special calibrated periodontal probe or sounding gauge to verify the position of the alveolar bone crest in relation to the gingival margin. The proportion gauge allows a fast diagnosis of the discrepancy on the width-to-length ratio of the clinical crown, directly inside the mouth through on a visual color-coded system. One end of the instrument has a T-bar tip with

a

b

c

d

e

f

14

..      Fig. 14.34  a Chu’s Aesthetic Gauge (T-bar and in-line tips); b width-to-length ratio on the T-bar; c intraoral analysis of the upper anterior teeth proportions; d analysis of width and length of the central incisor in relation to the red bands on the horizontal and vertical arms;

e width and length of the lateral incisor in relation to the blue band; f width and length of the upper canines in relation to the yellow band; g width-tolength ratio on the in-line tip; h measurement of the crown length with in-line tip; i measurement of the crown width with in-line tip

491 Composite Restoration on Anterior Teeth

g

14

h

i

..      Fig. 14.34 (continued)

vertical and horizontal arms to measure length and width at the same time, being used for teeth with normal alignment. The opposite end has an in-line tip with short and long parallel arms, helping to measure the length and width independently, in cases of crooked or crowded teeth where the use of the T-bar tip may be difficult (. Fig. 13.34a). Both tips have a predetermined ratio of about 78%, which is an average value for the population. The T-bar tip has a vertical arm, a horizontal arm, and an incisal guide. It is placed on the labial surface of the tooth, with the vertical arm parallel to the long axis of the teeth, on the central region of the crown, and the incisal guide touching the the incial edge. The vertical arm is used to measure the length of the crown, while the horizontal one measures its width. The instrument is made with a yellow material that contains blue, red, and black color bands. A particular color band on the vertical arm corresponds to the same color band on the horizontal arm, helping to ensure that the tooth is in proportion. The most common width/length dimensions for the upper central incisors (8.5/11 mm) correspond to the external ends of the red bands (. Fig. 14.34b). The most common dimensions for a lateral incisor (6.5/8.5 mm) correspond to the external ends of the blue bands, while the average values for the upper canines (7.5/9.5 mm) correspond to the external ends of the yellow bands. In . Fig. 14.34b, f, the dimen 

 

 

sion corresponding to each band on the T-bar tip and in-line bar tip can be observed. The measurements must begin on the central incisor, looking for which size ranges the other teeth must be evaluated (common, small, large, or extra-­ large), passing to the lateral incisor and then to the canine (. Fig. 14.34c–f). This way, it can be known if the width -to-­ length ratio of each tooth is correct, as well to know if the teeth have compatible sizes. On the case of small teeth, the measurement of the crown length will move downward (one full band) and the width toward the center (one full band) of the most common measurements. On this case, the measurement of the central incisor begins on the internal part of the red band, while the canine will start on the external end of the blue band and the lateral incisor on the internal end of the blue band. In large teeth, the measurement will move one band upward and outward, while the extra-large ones will move two bands. The in-line tip is designed to measure, independently, the length of the teeth with the longer arm and the width with the shorter arm, on the cases where the T-bar may not be used (. Fig. 14.34h–i). It works in the same way that the T-bar tip does, except by the fact that the horizontal arm on T-bar becomes the short arm of the in-line tip. For its use, first, the length of the central incisor must be measured, aligning the tool with the long axis of the dental crown (. Fig. 14.34h). To start the measurement, the inci 

 

 

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sal guide, which is the first black band, must be placed on the incisal edge as the starting reference to measure the length. To measure the width of the crown, the short arm must be aligned perpendicularly to the long axis of the tooth parallel to the incisal edge (. Fig. 14.34i). The measurements of the lateral incisor and canine are done in the same way.  

14.6 

Restorative Technique

14.6.1 

14

Previous Clinical Procedures

The first clinical step is the pre-procedural antisepsis of the patient’s oral cavity, using a chlorhexidine digluconate solution or another type of antiseptic mouthwash. The patient is asked to swish it in mouth for 30 s. The use of an antiseptic mouth rinse reduces drastically the emission of the contaminated particles to the surrounding atmosphere, during the use of a high-speed handpiece, helping to protect the dental health-care workers of infections by pathogenic bacteria, viruses, and fungi. A radiographic examination can also be performed to analyze the lesion depth and evaluate if there is any pathological periapical radiographic change. If the lesion depth is shallow or medium and there are no periapical changes, the local dental anesthesia can be performed. If the lesion is large and deep and there is doubt if the pulp has turned necrotic or not, the sensitivity thermal testing must be performed. In the absence of painful response after the application of the thermal stimulus, the test cavity preparation can be done, starting the tooth preparation without anesthesia, to evaluate if there is any painful response. If the tooth has a painful response to the test cavity, the anesthesia of the area should be performed. If the pulp has turned necrotic and endodontic treatment is necessary, it must be provided before the restoration is started. However, on the cases where the esthetic re-establishment cannot be postponed, the restoration may be  done  first, followed by the root canal access cavity preparation to start the endodontic treatment. In case the tooth is covered by biofilm or extrinsic stains, a prophylaxis must be performed with pumice or prophylactic paste without fluoride and brush, or with a prophy-jet device, which uses pressurized slurry of sodium bicarbonate or glicine powder, taking care not to injure the gingival tissue leading to bleeding. After choosing the kind of composite to be use, performing the shade determination, the esthetic analysis of the tooth to be restored and of the adjacent teeth, the occlusion evaluation must be performed with a thin double-sided two colors articulating paper (e.g., red and black), allowing a two-tone representation of static and dynamic occlusion. The first step is to inspect the eccentric contacts (dynamic occlusion). The paper is placed on the Miller articulating paper forceps, in a way that the red side is facing the tooth to be restored. The patient is asked that to occlude at centric occlusion (CO) and do protrusive and lateral excursive movements. The patient must open the mouth

and the presence of interferences during disocclusion movements be analyzed. After that, the paper is then turned in the forceps in a way that the black side faces the tooth to be restored. The concentric contact (static occlusion) is analyzed, asking the patient to close the mouth in CO and open it again. The color sequence can, of course, be altered. Whenever possible, the tooth-to-tooth contacts occurring during CO should not be included in the preparation outline, remaining over the intact tooth structure. In case it is not possible, care must be taken so that it will not be located over the tooth-restoration interface. It must be verified which teeth participate of the disocclusion guides, avoiding its modification when guides are working properly. Sometimes eccentric interferences can occur and should be evaluated and adjusted. The presence of wear facets must be verified, which indicates the presence of intense contacts on that area [3]. 14.6.2 

Tooth Preparation

In case of a caries lesion located on the proximal surface, without affecting the enamel on the labial or lingual surfaces, it is necessary to choose the most convenient entry direction, which can be the labial, lingual, or strictly proximal approach. The proximal approach should be chosen every time is possible, because it promotes the maximum preservation of the healthy remaining tooth structure. It can be performed in the absence of adjacent teeth, when there are lesions on both adjacent tooth surfaces, in a way that the entry may happen through the preparation on the neighboring tooth. It is also possible on cases of wrong positioning of the tooth or presence of diastemas, or even when the adjacent tooth has some type of restoration or temporary crown that can be removed (. Fig. 14.45a–l) [3]. Another option is to perform a dental separation. It can be done in two different ways (rapid and slow separation). The rapid or immediate separation uses mechanical separators which employ the wedge principle, such as the Elliot or Ivory (. Fig. 3.47a–c).  On those cases, only a topical anesthetic should be used on the interdental papilla on the way to reduce the painful sensation. The separation procedure must be performed slowly, considering the sensitivity reported by the patient. The injection of an anesthetic before the separation eliminates completely the sensitivity, increasing the chances to harm the periodontal tissue. After the separation is complete, obtaining the necessary access to the lesion, anesthesia should be performed before the tooth preparation. However, the patient discomfort and the chances of injuries to the periodontium have reduced the use of this technique. The slow or delayed separation technique is less traumatic. On this technique, the orthodontic elastic tooth separator (rubber rings of different thickness  as shown on . Fig.  3.48) is stretched with two pieces of dental floss and applied between the teeth, remaining for 1 or 2 days before the restoration. The ring must surround the contact area. If the ring is breaking during the application, the teeth can be  

 

 

493 Composite Restoration on Anterior Teeth

slightly separated with a wooden wedge and the region lubricated with a water-soluble glycerin gel, so the rubber can slide easily. It may be required, when the patient return on the next appointment, to replace the ring for a thicker one to be able to reach the necessary direct access to the proximal area [2, 3]. After this period the rubber ring is removed, the isolation of the operating field is performed, and a wedge is applied to maintain the space obtained. Then, a conservative tooth preparation and the restorative procedure are performed. When the gingival border of the caries lesion is subgingivally located, a wooden wedge should be placed between the teeth to protect the gingiva during the tooth preparation. In case the rubber dam isolation has been previously applied, the wedge will also protect the rubber sheet [31]. If the proximal contact was removed during the preparation, the wedge will promote an additional dental separation to compensate the thickness of the matrix band and help the restore of the contact point [31]. It must be inserted through the larger embrasure. If the wedge is going to be applied after the rubber dam isolation, the sheet must be stretched with the tip of the finger, first pressing firmly the rubber and the underlying soft tissues and then pulling the rubber and moving it far from the tooth. The wedge is inserted and the rubber is released (. Fig. 14.48b) [31]. After obtaining access to enter the lesion, the carious tissue must be removed preserving the maximum of the healthy remaining tooth structure possible. The entry must be performed with a round diamond point in a high-speed handpiece. The carious dentin tissue is removed using a round bur, of largest diameter possible, compatible with the preparation size, in a low-speed handpiece, or using dentin spoons of adequate size [31]. The final preparation dimensions are usually determined by the size, shape, and location of the lesion, as well as the necessary extension to obtain access to visualize the walls and use the instruments [31]. The preparation must be restricted to the removal of the carious tissue in the most conservative way. On the case of proximal entry approach, no bevels on the margins are necessary because there is no esthetic commitment.  

>> The tooth preparation is restricted to the removal of the carious tissue in the most conservative way. The final dimensions are determined by the size, shape, and location of the lesion, as well as the necessary extension to obtain access to the walls.

In case it is not possible to perform a dental separation, and the lesion is restricted to the proximal surface, the lingual entry approach should be chosen, preserving the labial enamel, even if undermined, to guarantee good esthetic results for not exposing the composite to visible areas. As the indirect vision is frequently necessary, a first surface reflection, clean and without scratches mirror must be used, allowing a clear view and without distortions [31]. Sometimes, on the upper arch, the direct vision may be obtained leaning the patient’s head backward, according to what is describe in 7 Chap. 2 (. Fig. 2.13a) [31].  

 

Before touching the tooth, the rotary instrument is positioned and activated on high speed with an air/water spray. The assistant directs the airstream from the air/water syringe toward the mirror and places the saliva ejector (SE) next to the operating field. The ideal is the use of high-volume evacuator (HVE) with a plastic tip with beveled end, placed close to the tooth surface (. Fig. 7.49a). The adjacent tooth must be protected with a steel matrix band. The initial opening must be performed in the correct incisogingival position of the lesion center, as close as possible to the adjacent tooth, without touching it. The rotary instrument is held perpendicular to the enamel surface, in a mesiodistal angle that places the neck of the instrument almost touching the adjacent tooth, in the region of the embrasure. It is directed toward the lesion until feeling the sensation of falling in a hollow space, which means that the lesion was reached (. Fig.  14.35a–d) [3]. Incorrect entry overextends the lingual outline to stress areas, such as the marginal ridges, unnecessarily weakening the tooth. The outline of the preparation must be the most conservative as possible, as sometimes smaller than the internal dimensions of the preparation (. Fig. 14.36a–f). The same instrument is used to enlarge the opening only enough for caries removal and convenience form, while establishing initial axial wall depth. Using pendular movements, the carious tissue is removed without increasing the opening size [3, 31]. Unless it is extremely necessary to remove the carious tissue, the preparation should not include the contact area, extended to the labial surface or subgingivally [31]. On the case of lingual entry approach, no bevel on the margins is recommended because no esthetic commitment occurs. In addition, the bevel may extend the restoration margins toward the centric contact areas or undergoes heavy masticatory forces, increasing the wear and susceptibility of fracture [3]. The labial entry approach should be used when: the carious lesion has already reached and destroyed the enamel on the labial surface; the labial surface was  destroyed and the lingual surface is intact; both labial and lingual surfaces were affected there is an faulty restoration on the labial surface; there is an irregular alignment of the tooth or facial positioning of the lesion and  the lingual approach would require excessive cutting of the tooth structure [3, 31]. The procedure is simpler because the direct vision can be used and the lesion or inadequate restoration are generally larger [31]. The opening of preparation has to allow the correct removal of the carious tissue but in the most conservative way possible. When there are two adjacent lesions to be treated on contiguous teeth, many times  one of them is larger than the other. When the preparation of the larger lesion is performed first, the preparation of the smaller lesion  can generally be even more conservative, due to the improved access provided by the larger preparation (. Fig.  14.48a–g). The opposite sequence must be followed when the material is applied during the restorative procedure, i.e. the smaller preparation is restored first [31]. After the anesthesia, the preparation can be done  before or after the rubber dam isolation. In both  

 

 

 

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a

b

c

d

..      Fig. 14.35  Entry direction for preparation opening (incisal view of extracted teeth assembled and cross sectioned to show the lesion and illustrate the procedure). a Incorrect entry position; b, c correct entry

14

cases, a wedge should be placed on the interproximal space to retract the rubber dam and the gingival papilla, improving the access to the gingival margin of the lesion [31]. The entry is performed with a round diamond point in a high-speed handpiece, and the carious dentin tissue is removed with a round carbide bur in a low-speed handpiece [31]. The tip of an exploratory probe must carefully inspect the DEJ to detect the presence of remaining carious tissue [31]. The removal of the carious tissue must start on the surrounding walls, reducing the contamination of the preparation, finishing on the axial wall. This way, if an accidental pulp exposure occurs, the risk of contamination of the pulpal tissue is reduced. The undermined enamel may remain since it will be reinforced by the adhesive restoration [31]. Tip

When there are two adjacent lesions to be treated on contiguous teeth, the preparation of the larger one is performed first, which allows the second preparation to be more conservative due to the improved access. The opposite sequence should be followed when the material is applied during the restorative procedure.

direction; d cross section of the finished preparation preserving the marginal ridge

Tip

The removal of the carious tissue must start on the surrounding walls, reducing the contamination of the preparation, finishing on the axial wall. This way, if an accidental pulp exposure occurs, the risk of contamination of the pulpal tissue is reduced. The undermined enamel may remain since it will be reinforced by the adhesive restoration.

Due to the important esthetic requirement on the labial surface and the difficulty to mask a butt joint restoration margin, a bevel can be prepared only on the cavosurface angle on the facial tooth surface. The main purpose of this procedure is to help masking the interface between the restoration and the remaining tooth structure. It is a small cut performed on the cavosurface angle on a 45° with the external surface, using a conical, flame, needle, or round-shaped diamond point in high speed, with an average width of 0.25–0.5 mm or larger [3, 31]. The marginal bevel creates a progressive transition between the restorative material and the tooth structure, helping to mask the restoration and improve the esthetics [31]. The larger the bevel width, the more likely is to obtain an excellence esthetic result.

495 Composite Restoration on Anterior Teeth

a

b

c

d

e

f

..      Fig. 14.36  Correct entry direction for opening the preparation from lingual approach (proximal view of an extracted tooth used to illustrate the procedure). a Correct entry angle in relation to the lingual

surface; b access to the lesion; c, d pendular movements to produce the proximal outline; e removal of carious tissue with a round bur in low-speed handpiece; f preparation finished

When composite materials started to be used to restore anterior teeth, the bonding to the tooth structure was restricted to the enamel tissue. Due to its many advantages, the bevel used to be always indicated on the entire enamel cavosurface angle of the preparation on those days. It increases the bonding area, improving the retention and the marginal sealing of the restoration; exposes a more reactive enamel which improves the quality of the acid etching; and cuts the prism transversally to create a better end-on etching pattern than when the prisms are etched sideways [3, 31]. The bevel also removes the prismless enamel layer, providing more

micromechanical retention. However, more effective bonding agents are available nowadays, for both enamel and dentin tissues, and the retention does not depend only on bonding to enamel. Therefore, it is no longer recommended to perform the bevel on the whole cavosurface angle. In addition, the bevel requires an extra cut of the tooth structure and makes the preparation procedure more aggressive. Considering that the restoration will probably fail after some year and will be replaced, the most conservative preparation is desirable. This way the bevel is currently only recommended on regions where the esthetic is fundamental, such as in facial surfaces.

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Some authors just contraindicate the bevel on any preparation margins, aiming the maximum preservation of the tooth structure. They suggest the application of some excess of composite covering the margin and the near tooth surface, creating some over contour, and attempting to mask the transition between the preparation and the restoration. It is also possible to make a restoration mock-up without bevel on the margins to evaluate the esthetical result. The composites of selected shades and opacities are applied in the preparation without any previous adhesive treatment. After curing, the mock-up is evaluated in relation to the esthetic result and can be easily removed afterward. If the result is not adequate, after its removal, the bevel can be performed before doing the final restoration. The restoration mock-up is more indicated in cases of tooth fracture or large Class IV cavities, when the preparation is not self-retentive, being easily removed by pulling out on  its margin with the aid of an exploratory probe. For Class III preparations, the removal of mock-up will be more difficult, being necessary the use of rotary instruments. In addition, the mock-up takes time and uses more restorative material, which will interfere on the costs of the treatment. However, it is certain that when a bevel is made on the margins with esthetic commitment, the chances to obtain a good esthetic outcome is higher, especially when a mock-up is not made. For this reason, the bevel on areas with esthetic commitment can be still recommended. On the other hand, in the cases of large preparations or fractured teeth, where the amount of tooth to be restored is larger than the remaining tooth structure, a larger bevel with 0.5–2  mm width on the entire cavosurface angle may be important to obtain the required retention [31]. The larger the bevel, the higher is the bonding area and the retention obtained. The dentist must take a decision on each case in relation to do or not the bevel on the margin, choosing between the maximum preservation and the esthetical or retention requirement of each preparation. On preparations where the gingival margin is too close to the CEJ, such as on the gingival walls of large Class IV, III, or Class V preparation, a careful evaluation is important to analyze if the bevel will not completely remove of the remaining enamel, resulting in bonding directly to the dentin and cementum on the cavosurface angle, which is much poor in relation to the bonding to enamel. If the gingival margin of the preparation is located on the root surface, no bevel is done on the cementum margin [31]. When there is a cavitated lesion reaching dentin, surrounded by a white or brown spot lesion on enamel that extends over the tooth surface, beyond the preparation outline, after finishing the preparation on the cavitated area, the margins should be extended to include all demineralized areas, using an round diamond point, restricted to the enamel tissue on the necessary depth to remove the lesion (. Fig. 14.38g–i) [31]. Due to the proximity of the pulpal chamber, the Class V carious lesions are shallow on the mechanic point of view, but deep on the biological point of view, since a pulpal tissue exposure may easily happen [3]. This must be avoided at all  

cost, and a stepwise excavation can be indicated when the dentist realizes that, if the preparation continues, an pulpal exposure may happen. On the cases of non-carious cervical lesions, it is important to identify its etiology before preceding the restoration of the lost tooth structure, avoiding the relapse of the problem. Once the etiological factor was diagnosed and treated, the tooth can be restored. The preparation is restricted to a small bevel on the incisal cavosurface angle, and a composite that provides adequate polishing can be used [31]. The decision to restore or not a cervical lesion on the buccal and facial surfaces is based on several factors. If it is a white spot lesion, which is a subsuperficial carious lesion without cavitation, preventive measurements can be applied to reduce the caries disease activity and arrest the lesion, such as biofilm control, dietary changes, and fluoride use, promoting its remineralization. A restorative intervention is not indicated [31]. The caries infiltration technique may also be applied, completely stopping the lesion progression, as it is described in 7 Chap. 16. If there is cavitation, the area must be restored, unless it is too superficial and the patient is able to clean, mechanically removing the biofilm from inside the cavity with the toothbrush, and there is no esthetic commitment. On the case of non-carious lesions, if they are small and the etiological factors were  identified and controlled, they can stay without being restored. If the area is hypersensitive due to dentin exposure, a desensitizer agent can be applied to reduce the pain, as discussed in 7 Chap. 18. If the sensitivity persists after the treatment, it may be necessary to restore the area, covering the dentin with composite [31]. If the cervical lesion is identified as the cause of biofilm retention and gingival inflammation, it should also be restored [31]. If a non-carious lesion is large and deep, the restoration of the defects is recommended to avoid its progression toward the pulpal chamber. In addition, very large lesions may compromise the fracture resistance of the tooth. The restoration of the area reinforces the remaining tooth structure and prevents the progression of the defect [31]. The inactive cervical caries  lesions may be stained (brownish or black) and shiny, sometimes presenting sclerotic dentin with high mineral density, in which the dentin tubules are obliterated by mineral deposition  and an increased layer of peritubular dentin. They are more resistant to the acid etching, impairing a proper bonding to the restorative material. The increase of the etching time may be desired on this situation or a gentle removal of the superficial sclerotic layer with round burs, exposing an underlying less sclerotic substrate [3]. If there are old faulty restorations, they are removed with a round diamond point on high speed. In case of large old restorations, sometimes it must be advisable to remove only the defective part and to perform a repair [3]. When there are located areas of color alteration  on the tooth surface, such as white, yellow, or brown, resulting from enamel hypomineralization, they may be removed and restored if the patient desires. The non-carious white lesions are very common and may or may not reach the underlying dentin. On this case, after the shade selection, the affected tissue is removed with a round diamond point, followed by a  

 

497 Composite Restoration on Anterior Teeth

bevel on the margins. As already described, the bevel is not mandatory, and related only with the masking of the restoarion margin. The acid etching and bonding application is performed, followed by the composite increments [27]. Another option for esthetic treatment of this kind of lesions is to use the resin infiltration technique, which requires a previous etching of the surface with a hydrochloric acid gel, followed by dehydration with ethanol and application of an infiltrant resin. Although this method was initially developed for caries lesions, good results were also obtained when applied on fluorotic lesions and other hypomineralized enamel lesions. In some cases, such as on Molar Incisor Hypomineralization (MIH), a previous opening of the surficial enamel layer with a bur is required before the infiltration (deep infiltration). The resin infiltration technique is a more conservative way for esthetical treatment of white lesions than the regular composite restoration. More details are presented in 7 Chap. 16.  

14.6.3 

Restorative Procedure

For all types of preparations, it is important that before any restorative procedure, the moisture of the operating field is under control. Any moisture contamination by saliva, blood and gingival crevicular fluid will result in total failure of the adhesion to the tooth structure, and consequently to a defective restoration. Therefore, especially for the beginners, the moisture control with the rubber dam isolation is easier and reliable. When working on the anterior teeth, the rubber sheet should be applied at least from right canine to left canine, usually without any clamp. However, on patients where the moisture control may be effectively performed by the assistant, the cotton roll isolation may be safety used. For that, the cotton rolls are placed and changed when moist, associated with saliva ejector and cheek retractor [2]. On the cases of cervical lesion, a retraction cord can be introduced into the gingival sulcus. When a total-etch adhesive system is selected, the next step is the application of a 32–38% phosphoric acid gel in the entire preparation. First of all, the proximal surface of the tooth adjacent to the preparation must be protected with the polyester or polytetrafluoroethylene (PTFE) strip (. Fig. 14.49c) [31]. Even though the accidentally etched enamel seems to be clinically normal after a few days, scanning electron microscopy images showed that the etched enamel is not completely remineralized up to 90 days [16]. The adhesive system selected must be applied according to the manufacturer’s recommendations. The acid etching is started on the enamel of the surrounding walls, up to 1 mm beyond the cavosurface angle or bevel, over the external tooth surface. After that, the gel is applied over the dentin, remaining undisturbed for 15 s [3, 31]. The etching beyond the margin will prevent that any excess of composite (flash) inadvertently applied over a non-etched area will stain within a short period of time due to microleakage [3]. The phosphoric acid acts over the enamel promoting a nonselective superficial removal of about 10 μm, followed by a further selective demineralization of about 20–30 μm deep,  

creating the characteristics of microporosities of the enamel etching pattern (. Fig.  6.55b) [3]. The by-products of the acid action over the enamel are water-soluble salts which are removed by the rinsing. The acid etching increases the surface energy and the surface area, allowing the penetration of the resinous fluid monomers into the microporosities, creating resinous tags responsible for the micromechanical interlocking. On dentin, the acid etching removes the smear layer, opens the tubules, and demineralizes about 5 μm of the underlying dentin, which represents approximately the thickness of a strand of hair divided by 10, exposing the collagen fibers network (. Fig. 6.53b). The preparation must be thoroughly rinsed away with an air/water spray for about 20–30 s [3, 31]. The spray is first applied on the adjacent teeth to prevent the acid-rich water to be projected over the patient, dentist, and assistant. The preparation must be carefully evaluated to verify if no acid residues remained. Then, the excess moisture is removed with the blot dry technique using a small cotton pellets, foam pellets, disposable applicators, absorbent paper, or suction with a cannula, resulting in a visibly moist surface but without pooled water [3, 31]. The surface must have a glistening aspect (. Fig. 14.38f‘). The dehydration of the etched dentin results in the collapse of the collagen fiber network of the intertubular dentin, preventing the monomer penetration into the labyrinth of nanochannels formed by the dissolution of hydroxyapatite crystals between the collagen fibers. On the other hand, pooled moisture dilutes the adhesive and results on the formation of bubbles and empty spaces in the adhesive layer, which becomes weak areas of the adhesive interface. If the access allows, a small cotton pellet may be placed inside the preparation, and the tooth surface, adjacent teeth, and the rubber dam can be dried with airstream, avoiding the dentin dehydration [3]. If the preparation walls are occasionally excessively dried, they can be rewet with an applicator soaked in water, followed by the dentin blot drying [31]. If any contamination of the preparation walls, with saliva or blood, happens after the etching, it must be repeated for 10 s on the entire preparation followed by rinsing and drying, to remove the residues that could interfere with the monomer impregnation [31]. When the cotton roll isolation is used, the cotton rolls must be replaced after the rinsing, taking care to prevent any contamination of the preparation [31]. Some authors recommend the application of a 2% chlorhexidine digluconate solution for 10 s after the acid etching, before the application of the adhesive, to promote the antisepsis of the preparation [3]. In addition, the main action of the chlorhexidine, in this case, would be the inhibition of the dentin matrix metalloproteinases, which are enzymes present in the dentin matrix released and activated by the acid etching. They are responsible for the degradation of the unprotected dentin collagen that can sometimes remain at the bottom of the hybrid layer, reducing the bonding durability [47]. Several studies have shown that the application of chlorhexidine after the acid etching is capable to significantly increase the bonding durability to the dentin substrate [9, 30], although the collagen degradation cannot  

 

 

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be completely stoped. When applied as part of the adhesive protocol, the excess must be removed with a small cotton pellet, leaving the surface visibly moist. The adhesive system must be taken into the preparation using disposable applicators such as Microbrush or small bristle brushes. They must have an adequate size to enter the preparation and take the solution to all surfaces. For that, different manufacturers produce applicators with several dimensions (. Fig. 14.37). When a total-etch two-bottle adhesive system (fourth generation) is selected, the primer containing hydrophilic monomers and solvents is applied to all surfaces followed by gently airstream, allowing the formation of a thin coat and evaporation of the solvent [31]. It is important to highlight that primer application to the enamel does not adversely affect the bonding [31]. The preparation walls must be inspected, and they should be uniformly shiny, as an evidence of sufficient coating [3, 31]. If dry spots remain, that means that, at this region, the collagen fibers were not correctly impregnated and remain unprotected, as well as dentin tubules are still open. On this case, the primer must be reapplied and the walls, dried and the preparation inspected again, as many times as necessary [31]. After that the adhesive (bond) is applied, which mainly contain hydrophobic monomers, followed by a soft airstream to leave a thin coat. As most adhesives are radiolucent, every effort should be done to avoid its pooling on the margins, which may create radiolucent radiographic images on the interface and may be misdiagnosed as a caries lesion [3]. After that, the adhesive can be light-cured for 10 s. The tip of the light guide must be placed as close as possible to the tooth, without touching it [31]. Even though the internal walls have to be entirely covered by the adhesive system, the film must be thin.  

14

Tip

To improve the bonding to the tooth structure, the following steps are very relevant: 55 After washing the phosphoric acid gel, the blot dry technique is recommended, resulting in a visibly moist surface but without pooled moisture, showing a glistening aspect. 55 After the application of the adhesive, the preparation walls must be inspected, and they should have a uniformly shiny aspect, as an evidence of enough coating. If dry spots remain, the adhesive must be reapplied. 55 The self-etching adhesive should be actively applied, rubbing the impregnated applicator over the preparation walls during the whole time recommended by the manufacturer.

When a total-etch one-bottle adhesive system (fifth generation) is selected, in which the primer and the adhesive are combined in a single solution, it must be applied in a similar way as it has already been described, followed by a soft airstream. If

..      Fig. 14.37  Disposable applicators. (1, 2, and 3) Applicators for tooth preparations; (4) applicator for root canal (Cavibrush Longo, FGM); (5) applicator for root canal (Endo Tim, Voco); (6, 7, and 8) disposable bristle brush with several dimensions; (9) bended applicators to improve the access to the preparation

dry spots remain, the adhesive must be applied once more until a homogeneous coat is obtained, following a light-curing for 10 s. The excessive thinning of the adhesive coat with a strong and too close airstream may adversely affect the bonding due to the oxygen inhibition layer  occur inside the monomers impregnated collagen network. This way, the hybrid layer will not be cured when receiving the composite [3]. In the cases where the preparation or the area to receive the composite does not present exposed dentin, after the etching, the surface can be dried with an airstream since there are no exposed collagen fibers that might collapse [31]. That will result in a white-opaque appearance. Therefore, the etched enamel may be dry or wet before the application of the adhesive system, but the etched dentin must never be dry. When using a two-bottle adhesive, if the enamel is air dried, the primer does not need to be applied. Just the hydrophobic adhesive will provide an excellent bonding. However, if the enamel is left wet, the primer must be applied, which is essential to interact with the superficial moisture. When a self-etching adhesive system is selected, the etching of the substrate is performed by the acidic monomers in the adhesive formulation by itself, without a separated etching step. In the two-bottle/two-step systems, the primer is applied during the time recommended by the manufacturer, generally from 20 to 30 s, followed by an airstream. After that the adhesive is applied and spread with an airstream, followed by light-curing 10 s. For the two-bottle/ one-step and for the one-bottle/one-step systems, it is applied during the recommended times, followed by an airstream and light-­curing. Similarly to the total-etch adhesives, after the self-­ etching adhesive application, the preparation walls should be uniformly shiny, as evidence of sufficient coating. Some studies have shown that the double application of the self-etching primers is capable to promote a more effective etching of the substrate, increasing the bond strength values [41]. In addition, the active application, moving the applicator over the surface, also improves the

499 Composite Restoration on Anterior Teeth

etching pattern and bond strength [41]. However, despite the kind of adhesive system selected, the manufacturers’ instruction should always be followed. Some studies have shown that self-etching adhesives can produce an insufficient enamel etching pattern, especially on intact enamel surface or on those areas covered by prismless enamel (. Fig. 6.1d). Therefore, when the retention is the main point for a restoration, a selective acid etching just of the enamel can be performed, leaving the dentin covered by the smear layer. It is followed by rinsing with an air/water spray, drying, and application of the self-etching adhesive on the entire preparation following the manufacturer’s instructions. On the cases where there is no exposed dentin on the area to receive the restoration, such as on diastemas closure or reanatomization of peg-shaped teeth, the use of acid etching approach has advantages in relation to the self-etching, to guarantee an effective etching pattern of the enamel prisms, obtaining the necessary micromechanical retention. When performing the restoration, it is important to remind that the tooth is a polychromatic structure, composed by tissues with different optical characteristics, being the enamel translucent and the dentin more  opaque. Therefore, to reach an optimal shade match, composites with different translucency levels should be selected. The composite is applied on a stratified layering technique, restoring each tissue with the most adequate material. It can be placed into the preparation with a hand instrument or directly from the composite capsule (compule). The first method is preferable, especially in cases where the access is restricted, since the diameter of the syringe tip is generally large [31].  

14.6.3.1 

 ervical Lesions on Facial or Lingual C Surfaces (Class V or Site 3 on Smooth Surfaces)

With the population aging associated with the success of the caries disease preventive measures, people are keeping their teeth much longer than in the past, sometimes during their entire lives, allowing gingival recessions and non-carious lesions to happen. This way, the number of Class V restorations performed in the dental offices has been substantially increased. To perform the restoration, after the pre-procedural mouth rinsing, prophylaxis, and shade selection, the anesthesia of the area must be done. Then, the position of cavosurface margin is evaluated, determining if it is supragingival, equigingival, or subgingival, which may adversely affect the access to the lesion. On most of the cases, the rubber dam isolation using a retraction clamp or the cotton roll isolation using a retraction cord allows an excellent operating field. However, if the biologic width has been invaded for a caries lesion, for example, surgery for its re-establishment must be previously performed [3]. In some cases, the gingival margin of the preparation is subgingivally located, and, although without invasion of the  biologic width,  the retraction cord does not provide an adequate displacement of the gingival

tissue, and the use of a retraction clamp would excessively harm the gingiva. On those situations, a trans-surgical restoration is indicated. For that, an intrasulcular incision with or without an internal bevel can be performed, producing a small envelope flap, allowing the application of the retraction clamp and rubber dam [3]. When the rubber dam isolation is selected in a single Class V preparation, the No. 212 or No. 212M retraction clamps should be used (. Fig. 14.39a–x). In case of preparations on two neighboring teeth, the No. 212L and 212R (. Fig. 14.38f, b‘) will allow both restorations to be performed simultaneously. If the clamp is not perfectly stable, low fusing compound or a light-cured gingival barrier may be applied to the region of the bow, touching the incisal edges or the occlusal surface of the adjacent teeth, providing stabilization, which prevents the clamp movement that could harm the tooth and surrounding soft tissues [3, 31]. When the cotton roll isolation is selected, an extra fine (size 000) non-impregnated gingival retraction cord is applied into the gingival sulcus before the preparation, to retract the gingiva and reduce the crevicular fluid flow (. Fig. 14.44c, d) [3, 31]. If the control of bleeding is necessary, the cord can be impregnated with an hemostatic agent. For each tooth, about 8–10 mm of cord is required, besides thin edge retraction cord packing instrument [31]. The cord insertion inside the crevice should start in the interproximal area, in the region of the gingival papilla, following to the other end slightly further than the limit of the tooth preparation. When an additional gingival retraction is required, a new cord can be placed over the first one. It should be avoided at all cost to harm the gingiva or cause ischemia of the tissue [31]. The gingival retraction can be associated with a cheek retractor, which displace the cheeks and lips from the operating field, allowing a proper restorative procedure to be performed. After the operating field isolation, the tooth preparation is inspected, evaluating the proximity of the axial wall to the pulpal chamber. On the cases of very deep preparations, an area with pink discoloration on the axial wall indicated that a remaining dentin layer of less than 0.5 mm exists, probably associated with clinically undetected microscopic pulp exposures [31]. On this situation, a thin layer of calcium hydroxide cement is applied, only over the pink dentin, with the goal to stimulate the formation of tertiary dentin. When accidentally etched by the phosphoric acid gel during the adhesive procedure, the calcium hydroxide cement is dissolved and its by-products are deposited on the preparation walls, adversely affecting the hybridization and the marginal sealing of the restoration. For this reason, a protective layer of GIC should be applied [11]. On the case of deep cavities, without any pink discoloration area, only a thin layer of the GIC should be used, restricted to the regions close to the pulp. On a shallow or medium-depth preparation, the application of any protective material is not necessary. Further information about the protection of the dentin pulp complex is available in 7 Chap. 9.  

 

 

 

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C. R. G. Torres and R. F. Zanatta

a

b

c

d

e

f

14

..      Fig. 14.38  Patient with several carious lesions on anterior teeth. a Baseline aspect; b application of a biofilm disclosing agent; c close view of the central incisors; d 1 week after receiving the biofilm control instructions; e shade determination; f rubber dam isolation using No. 212 L and R clamps. Removal of carious dentin tissue with round bur; g removal of carious enamel with round diamond point; h, i bevels on the incisal (conical diamond point) and cervical (round diamond point) cavosurface angles; j finished preparations; k, l acid-etching; m blot drying technique; n glistening aspect of the wet surface; o application of the adhesive system; p application of a gently airstream; q lightcuring; r, s application of opaque dentin shade composite (Amaris, Voco; shade O2); t application of translucent enamel shade composite (Amaris, Voco; shade TN); u contouring of last composite layer with a flat brush; v immediate result; w baseline aspect with lesions covered by biofilm; x 1 week after receiving the biofilm control instruction; y removal of the carious dentin tissue on the canine and lateral incisor; z bevel on the incisal cavosurface angle with a conic diamond point; a′ bevel on the gingival cavosurface margin with round diamond point; b′

preparation complete; c′, d′ Acid-etching; e′ blot drying with cotton pellets; f′ glistening aspect of the wet dentin; g′ application of the adhesive system; h′ light-curing of the adhesive coat; i′, j′ placement of matrix and wedge and restoration of the proximal walls with enamel shade composite; k′ application of enamel shade composite over the matrix band on the distal surface; l′ proximal surfaces restored; m′ application of composite in the undermined enamel areas; n′, o′ application of the dentin shade composite recreating the tooth contour; p′ application of enamel shade composite; q′ surface smoothening with a flat brush; r′ view of the recovered labial contour; s′ preparation of grooves dividing the lobes on the labial surface; t′ and u′ preparation of horizontal scratches to simulate the enamel perikymata, moving mesiodistally the diamond point; v′ polishing with a felt disc (Diamond, FGM) and diamond polishing paste (Diamond Excel, FGM); w′, x′ aspect 2 weeks after the end of the restorations. The white spot lesions on the premolars were still in a remineralization process. A good option for immediate color masking of those lesions is the use of the caries infiltration technique, described in . Fig. 16.12  

501 Composite Restoration on Anterior Teeth

g

h

i

j

k

l

m

n

..      Fig. 14.38 (continued)

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C. R. G. Torres and R. F. Zanatta

o

p

q

r

s

t

u

v

14

..      Fig. 14.38 (continued)

503 Composite Restoration on Anterior Teeth

w

x

y

z

a’

b’

c’

d’

..      Fig. 14.38 (continued)

14

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C. R. G. Torres and R. F. Zanatta

e’

f’

g’

h’

i’

j’

k’

l’

14

..      Fig. 14.38 (continued)

505 Composite Restoration on Anterior Teeth

m’

n’

o’

p’

q’

r’

s’

t’

..      Fig. 14.38 (continued)

14

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C. R. G. Torres and R. F. Zanatta

u’

v’

w’

x’

..      Fig. 14.38 (continued)

14

Although not mandatory, a bevel can be performed on places where there is enamel on the cavosurface angle, at 45° with the external tooth surface, using a No. 1111 conical-­ shaped or a flame-shaped diamond point in high speed, helping to mask of the tooth-restoration interface. On the gingival margin, due to the lack of access for the proper positioning of the conical or flame-shaped points, a No. 1011 or 1012 round diamond point can be used (. Fig. 14.38h, i). However, when the amount of remaining enamel is very small in this area, no bevel should be performed due to the risk of its complete removal. The etching using 32–38% phosphoric acid gel is applied first on the enamel and then extended to the dentin, remaining for 15 s. Then, the preparation is rinsed with air/water spray for 20–30 s and blot dried, using small cotton pellets, followed by the adhesive system application. The adhesive system should be dispensed from the bottle only after the acid etching and rinsing. At the moment the dentist is blot drying the preparation, the assistant dispenses the material into a Dappen dish, and it is immediately applied; otherwise the solvent in its composition will evaporate and the adhesive will become ineffective. The composite resins can be supplied in opaque syringes or in capsules with an applicator tip, namely compules, to be used with an injection gun. For the use of syringes, a  

small amount is removed using a sterile spatula and placed over a glass mixing slab or mixing pad. To avoid its curing due to the environmental light, it must be covered with an opaque object, such as a plastic opaque Dappen dish. Small portions are taken with a non-stick composite filling instrument and adapted into the preparation. The composite should be placed by using rapid shallow strokes, as if you were thumping the composite in place, reducing the chance of detaching from the cavity wall, which can create voids. After finishing the restoration, any material left over the glass slab is discarded. The encapsulated composites can be taken directly into the preparation and adapted with hand instruments [31]. However, on small cavities, it is hard to directly insert the encapsulated material due to the size of the delivery tip to be larger than the preparation access, being more recommended to apply it with a hand instrument [3]. After applying some increments into the preparation, the composite can start to stick on the filling instrument. When the instrument is taken away from the preparation, it can pull the composite back, and a gap is formed between the material and the wall. After curing, it will generate a permanent interfacial defect [27]. Therefore, it is extremely important to avoid the composite sticking to the instrument. For that, non-stick filling instruments made of anodized aluminum or

507 Composite Restoration on Anterior Teeth

highly polished stainless steel, or coated with titanium nitride or PTFE, as well as silicone or thermoplastic elastomer tips, should be used. In addition, the instrument should be kept clean during the procedure and the composite residues constantly removed using damp alcohol gauze [27]. It must also be evaluated if the instrument is not scratched, which will increase the sticking. If the composite is still sticking too much to the instrument, it can be wet with a very small amount of adhesive [31]. The ideal are adhesives without solvents, such as on the systems where the primer is in a separated bottle. There are specific products for this purpose, such as the Composite Wetting Resin (Ultradent)  and Signum Liquid (Kulzer). Some studies have shown that this procedure does not affect the bonding between the increments [6]. The primers or self-etching adhesives should be avoided, because they contain water and other solvents that adversely affect the bonding of new increments [5]. To avoid premature polymerization of the composite during the placement and modeling, the central focus of the overhead chair light should be moved away from the operating field, using a minimum illumination that comes from borders the light beam [3]. However, some overhead lighting has a built-in orange light source to prevent premature light polymerization of composite materials. To restore the dentin, a proper shade composite simulating the dentin opacity must be selected, according to the method that has already been described. The chroma may vary from the cervical region toward the incisal third, especially in the cases of the large restorations on anterior teeth. Therefore, more than one dentin shade may be required. Over it, an enamel shade composite must be applied. Besides its hue, chroma, and lightness, the thickness of the enamel shade layer will also interfere on the final color. To predict the effect of the layers thickness, superimposed shade guides can be used, as it can be observed in . Fig. 14.23 [2]. For Class V restorations, conventional viscosity or flowable composite can be used (. Figs. 14.38a–x‘, 14.39a–x, and 14.40a–i). It is important to select a restorative material that provides good polishing, reducing the biofilm deposition and gingival irritation. The microfilled composites are an excellent option for the cervical restorations. Besides producing a smooth surface, they have a low elastic modulus due to its reduced filler content, being more flexible and capable to dissipate internal stress generated during the masticatory loads, generally responsible for restoration displacement [3]. According to some studies, the elastic modulus is relevant on abfraction lesions, which are produced by stress concentration on the cervical area. The microhybrid, nanohybrid, and nanofilled composites are also good options for Class V restorations [31]. The flowable composites also have the same advantages related to the low elastic modulus, in a similar way to the microfilled ones. Besides improving retention, it also improves the adaptation of the restoration to the preparation walls [24]. On shallow Class V preparations, restricted to enamel, a single increment is generally enough, considering the maximum layer thickness of 2 mm for obtaining a proper light-­  

 

curing. For preparations with all the margins on enamel but with loss of dentin tissue, generally two increments are indicated. The first layer fills the lost dentin covering the axial wall, using an opaque composite. The second replaces the enamel using a more translucent material (. Fig.  14.38r–t). The composite is applied using a hand instrument, adapted on the preparation walls by gently thumping action with the instrument nib, instead of rubbing it over the surface [27]. On preparations with gingival margins on cementum, if the composite is inserted in a single increment, as the bond strength to enamel is higher than to the dentin, the shrinkage stress would break the interface between the composite and the dentin, on the gingival margin, instead on enamel margin, resulting in marginal gaps on the gingival cavosurface angle. A way to reduce this problem is to apply the first increments on the cervical and middle thirds of the preparation, in a way that they do not contact the enamel. Large cervical restorations may require the use of a darker shade on the cervical third and a lighter one on the middle and incisal thirds [3]. The increments must have a beveled transition and overlap in about 50% to avoid the sudden transition from one shade to another, which could be noticed on the surface of the restoration, impairing the esthetical result [3, 27]. A polychromatic effect may also be obtained using special tints, applied preferably over a cured composite layer and then covered with a enamel translucent shade [3]. The opaque dentin shade selected must partially cover the bevel when performed, helping to mask the transition between the restorative material and the remaining tooth structure. At the end, dentin shade material must be completely covered with a translucent enamel shade composite, recovering contour of the external tooth surface. The last layer may be contoured with a flat brush, for example, the No. 4A and 4B of Kota Company (. Figs. 4.45d, 14.38z, and 14.39o). Fahl [13] suggested the placement of final increment using a small sphere of composite, prepared with the tip of the index finger and thumb, which is placed in position and contoured with a hand instrument and flat brush. The rubber gloves must be thoroughly washed with water and dried before manipulating the composite, avoiding contamination with the glove powder, or use powder free gloves [27]. When the external layer is placed on more than one increment, it is common that air can be trapped on the junction between those increments. Therefore, a single final increment could cover the entire surface. As it is very difficult to place the exact amount of composite, it is preferable to apply a slight excess that can be removed during the sculpture or the finishing procedure [3]. During the increment placement, the dentist must not touch the external oxygen inhibition layer on the already light-cured increment, which has free methacrylate groups working as adhesive between each composite layer [3]. However, when the surface is touched by the dentist’s fingers, this layer is removed, being recommended the application of an adhesive coat, followed by an airstream [31]. Each layer must be light-cured for at least 20 s with an adequate light source (7 Chap. 13). The tip of the light guide should be protected with the clear PVC film sheet. Each layer  

 

 

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should not be more than 2 mm thick, to obtain an adequate polymerization on bottom of the increment [31]. It should also be avoided to connect more than two preparation walls at the same time on each increment, due to the C-factor (see 7 Chap. 13). The light beam must reach the preparation on a  

right angle with the tooth surface, where the preparation access was made, and the light guide tip must be placed as close as possible, almost touching the surface. The distance between the light guide tip and the tooth surface must never be larger than 1 mm. The dark shades are harder to light-cure

a

b

c

d

e

f

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..      Fig. 14.39  Restoration of the non-carious cervical lesion with conventional viscosity composite. a Initial aspect; b shade determination; c rubber dam isolation using a No. 212M retraction clamp; d bevel on enamel margin; e, f acid-etching; g rinsing; h blot drying; i Application of the adhesive system; j light-curing of the adhesive coat; (k–m) application of increments of dentin shade composite (GrandioSO – Voco); n, o application of enamel shade composite and surface smoothening with a flat brush; p restoration finished recreating the buccal surface contour of the cervical area. It can be observed the

shiny surface that corresponds to the superficial oxygen inhibited layer; q, r application of an oxygen blocking gel (Oxiblock, FGM) and light-curing through it; s after the polymerization, it can be observed the absence of the superficial shiny oxygen inhibited layer, compared with Figure p; t marginal finishing of the with a fine grit conical diamond point with non-cutting tip; u, v polishing with abrasive rubber (Silicone points, Microdent) and abrasive disc (Diamond Pro, FGM); w additional polishing with felt disc (Diamond Flex, FGM) and diamond past (Diamond Excel, FGM); x final result

509 Composite Restoration on Anterior Teeth

g

h

i

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m

n

..      Fig. 14.39 (continued)

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..      Fig. 14.39 (continued)

511 Composite Restoration on Anterior Teeth

w

x

..      Fig. 14.39 (continued)

than the lighter ones; also the opaque composites are harder to cure than the translucent ones. The manufacturer’s instructions must be followed in relation to the curing time. The composites should be at room temperature before use, since the materials that were recently removed from the refrigerator have a smaller polymerization [3, 39]. The oxygen on the atmosphere inhibits the polymerization of about 1–5 μm of the superficial layer of each composite increment. When a new increment is applied over it, the air is eliminated, and the layer of uncured monomers polymerizes together with the new material, providing bonding between them. However, the surface of the last composite layer of a restoration will not be completely cured, ­compromising its mechanical properties, especially if the surface does not receive a proper polishing. To overcome this problem, after the polymerization of the last increment, the surface can be covered by a transparent glycerin-based oxygen blocking gel and light-cured through it, eliminating the oxygen and allowing a complete polymerization, leaving a glazed aspect (. Fig.  14.39q, r). The gel is then  removed with an air/water spray [3]. The restorations must be analyzed in relation to the presence of flash or overhangs using a dental explorer, mainly on the gingival margin where usually more overhangs are detected. The explored must be placed inside the gingival sulcus, touching the root surface, and moved incisally. Any overhang detected must be removed with a thin fine grit conical-shaped diamond point, with non-cutting tip, as shown in . Fig.  14.66, avoiding an unwanted grinding of the root (. Figs. 14.66a, b and 14.39t). A scalpel blade can also be used to trim flashes and overhangs. The polishing may be performed with abrasive rubber point, abrasive discs, or felt discs with polishing pastes (. Fig. 14.39u–x). After finishing the restoration, the patients must be advised that abusive intake of staining agents, such as coffee, certain dark colored tees and soft drinks, several times a day, as well heavy smokers, can observe premature color alteration of the restorations. [34]. However, the occasional con 

 

 

 

tact with such substances do not result in a significant color change. In some cases, the cervical lesions can be associated with gingival recession, resulting on very long clinical crown. When the restoration of the entire defect is done with a tooth-colored composite, an esthetic commitment may occur, breaking the harmony of the width-to-length ratio and of the gingival zenith position. To overcome this problem, periodontal surgery, such as coronally positioned flap or a gingival graft, can be used. However, some patients cannot or does not want to undergo surgical procedures. On those cases, a gingiva-colored composite can be used, such as the Amaris Gingiva (Voco) or Beautifil II Gingiva shade (Shofu), making the tooth appears to have a shorter clinical crown (. Figs.  14.41a–l and 14.42a–a‘). The lost structure on the crown must first be restored with a tooth-colored composite, before restoring the most cervical area with the gingiva-colored material. First of all, the patient’s gingival shade is determined using a shade guide. For Amaris Gingiva,  he different shades are obtained associating one of three opaque flowable composites in the set, which is dark, light, and white, with the more translucent composite of conventional viscosity, with a standard pink shade (natural). Therefore, the final shade of the restoration is determined mainly by the selected flowable. It is also possible to combine the different opaque flowable composites trying to reach the patient’s gingival shade. The step-by-step procedure is presented in . Figs.  14.41a–l and 14.42a–a‘. Cotton roll isolation are used associated with a retraction cord, so the gingival shade can be evaluated during the procedure. A cheek retractor can also be very helpful for this kind of restoration. The flowable opaque composite is applied on a very thin layer and light-cured. Over it the composite with regular viscosity is placed and shaped, creating the contour of the edge of the free gingiva. The polishing is performed with abrasive rubber points and polishing pastes associated with felt discs.  

 

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b

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..      Fig. 14.40  Restoration of non-carious cervical lesion with flowable composite. a Initial aspect; b isolation and prophylaxis; c bevel on enamel margin; d application of the self-etching adhesive One-Up Bond F Plus (Tokuyama); e, f application of the first increment of

flowable composite Palfique Estelite Medium Flow (Tokuyama); g application of the second increment; h immediate aspect; i result after 1 week

513 Composite Restoration on Anterior Teeth

The cervical lesions can also be restored with conventional GIC or RMGIC, being specially indicated to elderly patients with high caries risk [31]. The tooth preparation is the same as for composites, with exception that no bevel is performed. Before the application, the preparation walls are etched with 10–11.5% polyacrylic acid for 20–30 s, followed by rinsing and drying. For the RMGIC the application of a primer can be recommended, according to each manufacturer’s instruction. The material is placed into the preparation on a single increment, and the excesses are quickly removed with hand instruments. To take the material into the preparation, it is possible to use a calcium hydroxide placement instrument, which has a small sphere on the nib. Another option is to use a gun design Centrix syringe (. Fig.  14.43a–f). A capsule (orange tube) model with a thin tip can be selected, allowing a better control during the application. The material is mixed and backloaded into capsule, no more than half full, followed by the plug, which must be fully inserted. The capsule is then  

placed into the syringe barrel. For the application, the syringe is squeezed with a slow and steady pressure. An amount of the material enough to fill the preparation is applied on a single increment. Due to its viscosity and sticky characteristics, the GIC or RMGIC are difficult to contour and sculpt. For this reason, cervical matrices are widely indicated for Class V restorations, because they contour and maintain the material in position during the setting or curing. When a conventional GIC is selected, metallic matrices can also be used (. Fig. 8.10a, b). However, when the light-cured materials are chosen, clear plastic matrices must be selected, holding the material while the light-curing is performed during the time recommended by the manufacturer (. Fig.  14.44a–l). After its removal, the major excesses are trimmed with a No.12 scalpel blade. When a GIC is used, a thin layer of cavity varnish or a light-cured adhesive must be applied over the restoration surface, receiving a soft airstream to create a thin coat. When an  

 

a

b

c

d

..      Fig. 14.41  Cervical restoration with gingiva-colored composite. a Initial aspect of the cervical lesions; b Amaris Gingiva composite (Voco); c shade selection of the gingiva; d gingival retraction cord inserted; e acid-etching; f application of the adhesive system; g application of the selected opaque flowable composite; h application of the pink shade composite; i contouring of the composite with a flat

paddle-shaped filling instrument; j immediate result; k clinical aspect after ending the adjacent teeth restorations and finishing procedures. The crown of the teeth 34 was restored with a tooth shade composite, before the restoration of the cervical area with a pink composite; l final aspect of the teeth 44–34 with cervical restorations with gingivacolored composite

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e

f

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..      Fig. 14.41 (continued)

515 Composite Restoration on Anterior Teeth

a

b

c

d

e

f

g

..      Fig. 14.42  Esthetic appearance improvement of anterior teeth using gingiva-colored composite. a Impacted right central incisor was treated with orthodontic traction. However, the correct repositioning was not obtained, and a composite restoration was previously performed in the incisal third of the crown. After some time, gingival recession resulted on the exposure of the root surface. The teeth 11 and 21 showed a strong darkening, in comparison with the other teeth on the arch. b Tooth 11 suffered pulpal necrosis and the 21 a dystrophic calcification of the pulp, which explained the color changes; c on close view, it was observed that even though the restoration of the tooth 11 had an adequate shape, the shade and translucency of the composite were not correct; d aspect after the endodontic treatment and external and internal bleaching of tooth 11 and external bleaching of tooth 21; e after the removal of the old restoration of the tooth 11, it was possible to observe its real position; f test of the silicone index previously made directly in the mouth over the old restoration; g protection of the neighbor teeth with PTFE strip (IsoTape, TDV) and

acid-etching; h application of the adhesive system Solobond M (Voco); i application of the opaque dentin shade composite (Amaris, Voco; color O1), covering part of the labial surface to mask the transition between the restoration and the tooth; j application of the enamel shade composite (Amaris, Voco; shade TL); k smoothening of the surface with a modeling silicone instruments (Micerium, Oraltech); l finished restoration; m measurement of the clinical crown length of the tooth 21 with a bow compass with two needle points; n and o planning of the desired dimensions; p and q enameloplasty for adjustment of the clinical crown length; r evaluation of the final dimensions with the compass; s proportional clinical crowns of both the upper incisors; t shade determination of the gingiva (Amaris Gingiva – Voco); u acid-etching of the root surface; v application of the adhesive system; w application of a pink color opaque flowable composite; x placement of the regular viscosity composite (Nature); y finished restoration; z and a′ clinical aspect of the smile before and after the treatment

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h

i

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o

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..      Fig. 14.42 (continued)

517 Composite Restoration on Anterior Teeth

p

q

r

s

t

u

v

w

..      Fig. 14.42 (continued)

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C. R. G. Torres and R. F. Zanatta

x

y

z

a'

..      Fig. 14.42 (continued)

14

adhesive is used, its light-curing is performed for 10 s. This procedure prevents the dehydration and cracks of the restorations or water sorption from the saliva during the initial setting stages. The RMGIC is generally more resistant to dehydration or water sorption and does not require protection. This is due to the fact that its resinous components immediate polymerization provides an umbrella effect, protecting the ongoing acid-base setting reaction. However, the manufacturer’s instructions must be strictly followed for each material [31]. The GIC restoration can be finished and polished only after the end of the setting reaction, about 24 h the placement into the preparation. However, the RMGIC may be immediately finished and polished. Even after the final setting, care must be taken to not dehydrate the GIC restoration surface during the finishing and polishing procedures. Conventional rotary instruments can be used under water spray. Rubber points and discs may be used lubricated with glycerin gel or petroleum jelly. Polishing pastes and felt discs can also be used [31]. Some brands of RMGIC present a fluid resin, called finishing gloss, that can be applied over the restoration after the polishing, spread with an airstream and light-cured.

14.6.3.2 

Proximal Lesions Without Involvement of the Incisal Edge (Class III or Site 2, Sizes 1–3)

During the restorations on anterior teeth, every time possible the rubber dam isolation at least from right to left canine should be performed, because it allows a better visualization of the lingual surface. In general, there is no need to use clamps, unless it is not possible to stabilize the rubber sheet with dental floss ligatures on the canines, or rubber stripes on the distal surface of the last isolated teeth. In patients with little salivation, the rubber dam isolation is acceptable. The preparation is inspected and pulpal protection performed when necessary. For preparations restricted to the proximal surfaces, without adjacent tooth or with a temporary crown or restoration that may be easily removed, the restoration may be performed with hand instruments, without the use of a matrix, similarly a Class V restoration (. Fig.  14.45a–l). However, every time there is contact between the tooth that will be restored and the adjacent, a protective polyester or PTFE strip (IsoTape – TDV) must be placed between them during the acid etching, adhesive application, and light 

519 Composite Restoration on Anterior Teeth

a

b

c

d

e

f

..      Fig. 14.43  Use of gun design Centrix syringe to apply restorative materials. a Different types of capsules; b loading the material into the capsule; c, d placement of the plug; e placing the capsule into the syringe barrel; f syringe ready to use

curing. This procedure prevents undesirable etching of the intact neighbor tooth surface and bonding between the tooth to be restored and the adjacent one. The strip used for protection can be discarded, and a clean and new polyester strip is placed and wedged before applying the composite to perform the restoration (. Fig.  14.47a–u) [31]. The placement of matrix after the bonding procedure reduces the chances of adhesive pooling on the margins close to the matrix.  

Tip

When there is contact between the preparation be restored and the adjacent teeth, a protective polyester or PTFE strip must be placed between them during the acid etching, adhesive application, and light-curing, preventing undesired etching and bond to the neighbor tooth.

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However, sometimes, the wedge insertion may cause fracture of some undermined enamel on the cavosurface angle, which will be permanently lost. In this case, the composite is applied over non-etched and bonded enamel, resulting on marginal microleakage on this area. One possibility to overcome this problem is to apply the matrix and wedge before the acid etching. Therefore, it would at the same time protect the neighbor tooth from etching and bonding and assist the tooth restoration. However, special attention must be given to remove any pooled excesses of adhesive on the

margins, using airstream, and dry microbrush applicators if necessary. The purpose of the matrix and wedge placement is to hold the composite inside the preparation, helping the contouring and shaping of the external restoration surface, improving the isolation, eliminating or reducing overhangs, and simplifying the finishing procedure. The wedge holds the strip in position, allowing a slight dental separation to compensate the matrix strip thickness, if the contact has been completely destroyed by the lesion [31].

a

b

c

d

e

f

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..      Fig. 14.44  Restoration with RMGIC using clear cervical matrix. a Cervical matrices (TDV); b initial aspect of the non-carious cervical lesions; c, d placement of the gingival retraction cord; e primer application (Vitremer, 3M); f light-curing of the primer coat; g fitting

test of the cervical matrix; h restorative material application using Centrix syringe; i positioning of the matrix before light-curing; j polishing with abrasive rubber (Silicone tips, Microdont) after 7 days; k application of the glaze coating; l final result

521 Composite Restoration on Anterior Teeth

g

h

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k

l

..      Fig. 14.44 (continued)

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C. R. G. Torres and R. F. Zanatta

Due to the fact that the proximal tooth surface is convex inciso-gingivally and the polyester strip is flat, it may be necessary to shape it to adapt to the desired tooth contour. A way to do this is to draw it across a hard and rounded object, such as the round end of a clinical tweezer. The amount of convexity created will depend on the contour necessary [31]. Several pull movements with strong pressure may be required to obtain enough convexity (. Fig. 14.46). The matrix strip is placed between the teeth and analyzed if it provides the adequate contour to the sur 

face to be restored. It must be extended at least 1 mm further than the gingival and incisal preparation margins. If the strip does not slide through a tight remaining contact or sharp preparation margin, a small immediate tooth separation can be obtained inserting a wedge in the interproximal space, allowing the passage of the strip. After that, the wedge is removed, and the matrix is taken in the desired position inside the gingival sulcus, between the gingival papilla and the tooth surface. Then, the wedge is inserted tightly once again [31].

a

b

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e

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..      Fig. 14.45  Restoration restricted to the proximal surface. a Carious lesion with direct access due to the absence of the adjacent tooth; b opening of the preparation with round diamond point; c removal of the carious dentin tissue; d preparation completed; e, f Acid-etching; g

blot drying; h adhesive system application; i, j application of dentin shade composite; k application of enamel shade composite; l final result

523 Composite Restoration on Anterior Teeth

g

h

i

j

k

l

..      Fig. 14.45 (continued)

Tip

To shape a flat polyester strip, draw it across a hard and rounded object, such as the round end of a clinical tweezer, until it creates the necessary contour.

The wedge is inserted into the interproximal space using a mosquito forceps with a curved end, preferably on the opposite side of the preparation entry. In other words, it is facially inserted when lingual access was performed and

vice versa, always apically to the gingival cavosurface angle. It must be kept as short as possible to avoid conflicts with the access area, not hindering the placement of the restorative material [3, 31]. If the preparation has a facial access, the pad of the index finger of the left hand, for the righthanded people, or of the right hand for the left-handed ones, can be positioned over the lingual aspect of the strip, pressing it toward the remaining tooth structure. The labial portion is reflected away from the access with the thumb (. Fig.  14.47o). If the wedge is too long and interferes on this procedure, it must be shortened [31]. The convex shape  

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natural enamel, the entire lingual and central area of the preparation, including the contact area, can be restored using dentin shade composite, leaving a small space on the labial surface that later is covered by enamel shade material (. Fig. 14.47p).  

>> When there is no remaining dentin on the preparation, or when it extends from labial to lingual surface, it is essential to use an opaque dentin shade composite; otherwise the restoration will have a darker aspect with half-moon margins.

..      Fig. 14.46  Contouring of the polyester strip with the round end of a clinical tweezer

of the finger pad will allow the ideal contour of the lingual surface, which is concave. Then, the composite is placed inside the preparation using a stratified layering technique, employing a non-stick composite filling instrument with a flat- or round-shaped nib like a plugger (. Fig. 14.47p). On the last layer, the material is placed with a slight excess. The major excess is removed with the filling instrument or dental explorer before closing the matrix. The labial aspect of the matrix strip is placed over the labial tooth surface, keeping in position with the thumb, applying a slight pressure for contouring the composite. The material is then light-cured through the matrix (. Fig.  14.47q–s) [31]. After that, an additional light-curing is performed placing the light guide tip on the lingual surface.  

 

14

Tip

If the preparation has a facial access, the pad of the index finger can be placed over the lingual aspect of the matrix strip, pressing it toward the remaining tooth structure, creating the ideal concave contour of the lingual surface. The initial composite increments can be placed inside the preparation using a non-stick composite filling instrument with a flat- or round-shaped nib like a plugger.

When there is no remaining dentin on the preparation or when it extends from labial to lingual surface (. Fig. 14.43a), the use of an opaque dentin shade composite is important; otherwise, most of the incident light over the labial surface will pass through the restoration instead of being reflected. This will result on a darker aspect to the restoration, with half-moon margins, due to the dark background of the mouth. The use of an opaque shade composite eliminates this problem, reflecting part of the incident light and increasing the lightness of the restoration. On teeth with less translucent  

On teeth with very translucent enamel, it is advisable to start the restoration on the lingual and proximal surfaces, with a thin enamel shade composite layer, followed by the restorations of the central area with dentin shade material, which is finally covered with a thin enamel shade layer (. Fig.  14.38i‘–r‘). On those cases, the composite placement is started over the matrix on the lingual surface, creating a background for the following increments. After that the proximal surface is also restored with enamel shade, leaving a space in the central area for placement of dentin shade composite. The first increment of enamel shade composite must be very thin. After its light-curing, the increment can be evaluated and, if necessary, more material be applied to reach the adequate enamel thickness. The enamel shade composite layer should be about 0.2–1 mm thick, continuous and preferably of a single shade [2]. The dentin shade is then applied, preferably in a cervico-incisal direction. An enough space for the final enamel shade layer must be left, which can be evaluated looking in an inciso-cervical direction. A sphere of enamel shade composite is prepared, placed, and contoured with a flat paddle-shaped hand instrument [2]. After that, the matrix strip must be reflected over the labial tooth surface, covering the composite. The cervical edge of the strip is pulled toward the incisal edge to avoid cervical overhangs [3]. The lightcuring is performed through the strip, creating a very smooth surface. It is very important to ensure that the entire area to be restored was filled with composite, especially on the margins [3]. If two adjacent restorations in neighbor teeth are performed simultaneously, they can be restored at a single appointment. The preparation with a smaller access must be restored first (. Fig.  14.48a–a′). If there was any excess or over-contour at the end of the restorative procedure, the finishing with an abrasive strip, abrasive disc, or diamond point must be performed before starting the next restoration. If the adhesive system was applied to both preparations simultaneously and the second preparation was contaminated with residues generated by the finishing, it has to be rinsed and etched and receive the adhesive application again, before any composite is placed. If a lingual access was performed, the same principles in relation to the application of the increments are valid  

 

525 Composite Restoration on Anterior Teeth

a

b

c

d

e

f

..      Fig. 14.47  Composite restoration through the facial access. a Defective restorations removed; b shade determination; c preparation of a bevel on the labial cavosurface angle; d acid-etching; e rinsing; f blot drying with a cotton pellet; g application of the adhesive system; h application of a polyester matrix between the teeth to avoid undesired bonding; i light-curing of the adhesive; j placement of matrix and wedge and insertion of dentin shade composite (Opallis – FGM); k, l last increment of enamel shade composite inserted followed

by matrix closing; m light-curing through the closed matrix; n aspect of the first restoration completed; o placing of matrix and wedge and positioning of index finger for the second restoration. p insertion of the dentin shade composite, leaving enough space for application of a enamel shade layer; q application of enamel shade composite; r matrix closed; s light-curing through the matrix; t immediate results showing the dehydration of the teeth; u final aspect after the polishing

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g

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..      Fig. 14.47 (continued)

527 Composite Restoration on Anterior Teeth

o

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t

u

..      Fig. 14.47 (continued)

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C. R. G. Torres and R. F. Zanatta

a

b

c

d

e

f

14

..      Fig. 14.48  Restoration of proximal lesions through the lingual access. a Initial aspect of the lesion; b stretching the rubber before placing the wedge; c opening of the larger cavity with a round diamond point; d removal of the carious dentin tissue with round bur in low-speed handpiece; e opening of adjacent lesion through the access of the larger lesion; f removal of the carious dentin tissue; g finished preparations; h acid-etching; i application of the adhesive system; j application of the matrix strip between the teeth to avoid undesirable bonding during the light-curing of the adhesive coat; k insertion of matrix and wedge for restoration on the smaller preparation; l matrix closed over the lingual surface before light-curing of the last increment; m insertion of matrix and wedge to restore the larger

preparation; n, o placement of composite (Opallis, FGM) and adaptation of increments with round-shaped nib filling instrument; p placement of the last composite increment; q closing the matrix over the lingual surface; r initial aspect; s finishing with pointed football shape fine grit diamond point; t removal of the cervical excess with a contour carbide carver (TZC12, Thompson/Miltex); u removal of excess with a No. 12 scalpel blade; v, w finishing of proximal surface with abrasive strip (3M); x, y polishing of lingual surface with abrasive rubber points in a decreasing grit size sequence (Microdont); z polishing with felt disc (Diamond Flex, FGM) and polishing paste (Diamond Excel, FGM)

529 Composite Restoration on Anterior Teeth

g

h

i

j

k

l

m

n

..      Fig. 14.48 (continued)

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C. R. G. Torres and R. F. Zanatta

o

p

q

r

s

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v

14

..      Fig. 14.48 (continued)

531 Composite Restoration on Anterior Teeth

w

x

y

z

..      Fig. 14.48 (continued)

(. Fig. 14.48a–a′), even though the labial and proximal surfaces are restored first, and finally the lingual one. The lingual surface does not require an enamel shade composite because this area cannot be seen during the patient’s daily life. On preparations restricted to the proximal surface, generally, there is no need to use dentin shade composite, unless on large and deep preparations. Furthermore, on this situation, if there is no adjacent tooth, the composite may be applied without the use of a matrix. However, if the access to the strictly proximal preparation was made through the lesion on an adjacent tooth, the use of the matrix simplifies the restorative procedure, avoiding the occurrence of overhangs.  

14.6.3.3 

 roximal Lesions with Involvement P of the Incisal Edge (Class IV or Site 2, Size 4)

This kind of lesion may be a result from carious lesion progression or fractures caused by dental traumas on this area. The composite indicated for this situation must have good physical properties to resist to the masticatory forces, besides providing an adequate final esthetics (. Fig. 14.49a–o). The procedures related to isolation of the operating field, pulpal protection, and application of the adhesive systems are the same as it has already been described. On this type of prepa 

ration, similarly to the lesions without involvement of the incisal edge, the use of a polyester clear matrix is essential for the correct restoration of the anatomical shape of the lost surfaces. The matrix strip must be inserted into the gingival sulcus between the papilla and the tooth surface. The dentist folds the strip end to end to form a loop, which is placed and pushed down toward the gingival sulcus with the tip of the index finger (. Fig. 14.49f). The wedge must be inserted in the largest embrasure, having a certain height that does not invade the preparation. The index finger will be positioned over the lingual aspect of the strip, pressing it toward the remaining tooth structure, creating the lingual contour. The labial portion is reflected away from the labial surface with the thumb. After that, the matrix is evaluated from all possible directions, to verify if on its interior there is an adequate shape and contour to restore the tooth’s anatomy. A very common problem at this moment is the improper matrix contour on the region of the mesiolingual or distolingual external line angles to be restored [31]. Due to the flexibility of the polyester strip and the fact that it is originally straight, on the region of the external line angles, generally the matrix does not present the adequate contour, which can be observed by looking the positioned matrix from the incisal edge. To create the correctly contour, a small fold on the matrix at this region can be created with the tip of paddle-shaped hand  

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instrument. While the index finger pad is kept pressing the matrix on the lingual surface, the instrument tip is moved incisocervically on the region of the lost external line angle, toward the intact angle of the adjacent tooth (. Fig. 14.49g). The enamel shade composite is placed on a very thin layer,  

over the matrix secured by the index finger pad, which is light-cured, creating the contour of the lingual surface (. Fig.  14.49h). Then, the same composite is placed on the region of proximal surface (. Fig.  14.49i). Before light-­ curing, the matrix must be pulled over the labial surface,  

 

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b

c

d

e

f

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..      Fig. 14.49  Restoration of Class IV preparation using polyester clear matrix. a Defective restoration removed; b preparation of a bevel on labial enamel margin; c protection of the adjacent tooth with a PTFE strip and acid-etching; d application of the adhesive system; e light-curing of the adhesive; f insertion of the matrix into the gingival sulcus, between the interdental papilla and the tooth, surrounding the tooth, pressing it cervically with the index finger; g insertion of wedge and placement of the index finger pad pressing the strip over the lingual surface, followed by making a small fold on the matrix in the distolingual external line angle, with the tip of paddle-shaped hand

instrument; h restoration of the lingual surface with enamel shade composite Z350 XT (3M/ESPE); i application of enamel shade composite to restore the distal surface; j before light-curing the matrix is closed; k distal surface completed; l insertion of dentin shade composite; m insertion of enamel shade composite, followed by the matrix closing. A paddle-shaped hand instrument may be placed internally into the matrix, on the region of the external line angle, while pulling the matrix, to guarantee the proper contour before the light-curing; n aspect after finishing with the teeth yet dehydrated due to the isolation; o result after polishing

533 Composite Restoration on Anterior Teeth

g

h

i

j

k

l

m

n

..      Fig. 14.49 (continued)

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C. R. G. Torres and R. F. Zanatta

o

..      Fig. 14.50  Transparent crowns forms with the labial side removed placed on a fractured tooth

..      Fig. 14.49 (continued)

avoiding the occurrence of excess on the proximal area (. Fig. 14.45j, k). This way, the regions harder to restore will be already concluded. After light-curing, the dentin shade composite is then incrementally placed in the central region, leaving space for the restoration of the labial surface with enamel shade composite (. Fig.  14.49l). The dentin shade composite should cover half of the bevel width, helping to mask the tooth-­restoration interface. After that, the enamel shade composite is placed and contoured, the matrix is pulled over the labial tooth surface, and the light-curing is performed through the matrix (. Fig. 14.49m). Care should be taken when closing the matrix strip, avoiding pulling it too strong. That would do the material flow toward the incisal edge, resulting on a restoration subcontour on the region of the external line angle with the labial surface. To avoid this problem, paddle-shaped hand instrument can be placed internally to the matrix, in the region of the angle, while pulling the matrix, to guarantee the proper contour before the light-curing (. Fig. 14.49m). If there is a failure on the contour, more composite can be applied to obtain the required shape. After the end of filling procedure and matrix removal, an additional polymerization must be performed from the labial and lingual approaches. In case of large dental fractures or caries lesions that resulted in the loss of the two incisal point angles (mesiolabioincisal and distolabioincisal), the same restorative procedure described can be used, using polyester strips, first restoring the lingual surface and applying enamel shade composite over the matrix, secured by the index finger pad, and then one proximal surface at a time. Then, the dentin shade composite is applied, finishing with the application of the enamel shade material over the entire labial surface. However, in those situations, the transparent plastic crown forms or the palatal silicone index techniques can also be applied. The transparent crown form technique consists in selecting a crown with a size compatible to the tooth to be restored (. Fig. 8.13a, b). It must be cut to fit correctly to the remaining tooth structure. It can be used in two different ways. On the first way, the composite is applied inside the crown form,  

 

 

14

 

 

placed in position, the material excess that flowed through the margins is removed, and the light-curing is performed. On this case, it is important that, before filling the form, a small hole is made in the incisal edge, which will help the flowing of composite excess. This technique presents as disadvantage the fact that the composite is placed on a single increment, making difficult to obtain a polychromatic restoration simulating the natural tooth. It is also hard to control the marginal overhangs, and there is a larger risk to have air bubbles entrapped inside the restoration. As they have some standard shapes, they may not adapt to all teeth, besides being harder and thicker than the polyester strips, which adversely affects the passage through the proximal contact region [3]. The second way to use the crown forms is to select a crown that better adapts to the tooth and then cut off the labial side maintaining the lingual, proximal, and incisal areas intact [3]. The crown is placed in position and wedged. The composite is then incrementally applied, creating a polychromatic restoration (. Fig. 14.50). The technique of the palatal silicone index, which is a custom-made matrix, is performed using a plaster model of the fractured tooth with the wax-up of the restoration (. Figs. 14.51a–u and 14.52a–x) or directly in the mouth when a defective restoration is present (. Fig.  14.62a–d′). On the first way, an alginate impression of the dental arch must be taken previously to the restorative procedure, obtaining a plaster model [12]. Over this model, the wax-up of the future restoration is performed, sculpting the ideal anatomy on every surface. A putty silicone impression material is applied directly with the fingers to the model (trayless impression), over the waxed tooth to be restored and some adjacent ones (. Fig. 14.51j, k). After the curing, the impression is removed. Then, with a scalpel blade, the labial part of the mold is removed, remaining only the lingual and proximal areas and the incisal edge (. Fig. 14.51l). The adaptation of the silicone index is tested placing it in position. Outside the mouth, a thin layer of the enamel shade composite is applied over the lingual surface of the silicone index, on the area of the restoration, slightly further than the cavosurface angle. It is placed in  

 

 

 

 

535 Composite Restoration on Anterior Teeth

­ osition, evaluating if the composite applied is touching the p remaining tooth structure, followed by the light-curing (. Fig.  14.51m–o). It is always better to apply a thin layer because it is easier to add composite than to remove. The silicone index is then removed from the position, remaining the layer of enamel shade composite on the lingual surface  

(. Fig.  14.51p). Then, a thin filament of the opaque dentin shade composite is applied on the incisal edge to simulate the effect of the opaque halo (. Fig. 14.51q) [2]. The opaque halo has a similar shade to the cervical area; therefore, the same composite shade should be used [1]. Then, the dentin mamelons are made with the opaque dentin shade material  

 

a

b

c

d

e

f

..      Fig. 14.51  Restoration technique using palatal silicone index and previous wax-up of the restoration. a Fractured teeth; b wax-up of the restoration over a plaster model; c rubber dam isolation; d preparation of bevel on the labial cavosurface; e acid-etching; f rinsing; g blot drying; h application of the adhesive system; i Light-curing of the adhesive; j, k silicone modeling of the over the plaster model; l cutting of the labial side with a scalpel blade; m test of the silicone index; n application of the enamel shade composite in the index (Amaris –

Voco, shade TN); o index with composite taken in position; p lingual surface completed; q Application of a small filament of the opaque dentin shade composite on the incisal edge to simulate the effect of the opaque halo; r restoration of dentin lobes with dentin shade composite (Amaris, Voco; shade O2); s application of high-translucency composite between the lobes (Filtek Supreme, 3M/ESPE; shade TB); t application of enamel shade composite (Amaris, Voco; shade TN); u polishing with felt disc and diamond paste; v final result

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g

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..      Fig. 14.51 (continued)

537 Composite Restoration on Anterior Teeth

o

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s

t

u

v

..      Fig. 14.51 (continued)

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C. R. G. Torres and R. F. Zanatta

(. Fig.  14.51r). Between the mamelons tips and the opaque halo, a highly translucent composite is placed to create an opalescent halo (. Fig.  14.51s). The selection of the highly translucent composite to be used must be performed before the isolation, placing small portions (small spheres) of different translucent composites touching the incisal edge of the adjacent intact teeth, without any type of adhesive, followed the light-curing. The patient is asked to open and close the mouth. The effect can be verified with and without the lower incisors on the back. For this step, really opalescent composites can be used, or non-opalescent ones associated with a thin coat of blue tints to increase the bluish opalescent effect between the lobes. If present on the adjacent teeth, other esthetic characteristics, such as white spots, may be created with white opaque tints [31]. The external surface is covered by the medium translucent enamel shade composite (. Fig. 14.51t). . Figure 14.52a–x shows a sequence of clinical procedure to restore a fractured tooth using a silicone index, associated with the cementation of a glass fiber post to improve retention. After the preparation of the root canal with the adequate bur, a dual-cure adhesive system was applied and then post cemented with dual-cure resin cement. The enamel and dentin shade composites were applied in the same way as it has already been described. On the attempt to reproduce the opaque white patches on the adjacent teeth, which are areas of enamel hypomineralization caused by fluorosis, a white opaque tint was applied between the layers of enamel shade composite using a disposable applicator.

washed with sterile saline solution before the application of the protector [3]. Then, the calcium hydroxide powder is applied by means of a very small and sterile applicator, placing the material without pressure. When the pulp curettage is performed, it must be done in the most conservative way possible, cutting the contaminated superficial tissue and covering it with calcium hydroxide [3]. The pulpotomy should only be indicated in the cases where there is incomplete root formation, but pulpal tissue was contaminated due to exposure to the oral cavity for a long period of time. It consists of the removal of the inflamed coronary pulp tissue, maintaining the integrity of the radicular pulp. However, the pulp tissue must present characteristics of vitality, from a macroscopic perspective, at the moment of cutting [3]. More details can be seen in 7 Chap. 9. On the cases of complete root formation but with large microbial contamination, due to long time exposures to the oral cavity, the pulpectomy should be performed. When the pulp is necrotic, and the tooth has an incomplete root formation, apexification techniques need to be applied. When the dentist decides to maintain the pulp vitality and perform a pulpotomy, it should be verified if the tooth does not present spontaneous pain and the pulp presents firm consistency, resistance to cut, and moderate to slight bleeding with bright red color, that stops in a few minutes after cutting. Those parameters are the most important one to determine the success. The more recent the pulp exposure had happened, the greater the success  probabilities of the treatment, even though old exposures can still show positive 14.6.3.4  Restoration of Fractured Teeth results, especially in younger patients. In addition, the size of The restoration of fractured teeth is a great challenge for the the pulpal exposure does not determine the success, because operative dentistry. They may involve one or more tissues, it may be obtained in small as large ones. The consistency is with different incidences:  only enamel (21%), enamel and also not a good parameter to predict the success. Liquefied dentin (57%), enamel-dentin-pulp (6.4–18.3%), and enamel-­ pulps have a bad response to the treatment due to the insufdentin-­pulp and periodontium (4.3–10%). In some cases, the ficient blood flow. Teeth with incomplete root formation and conservative pulp treatment is possible and desirable, espe- thin root walls generally provide a better prognosis [3]. It cially in the cases of incomplete root formation, where the must also be evaluated if the tooth may be restored without tooth remains with a wide open apex and fragile root canal the need of retentive post inside the root canal. On the cases where no pulpal exposure occurred, but walls, with enhanced risk of root fractures. The pulpotomy will promote the pulp revascularization and the continued there is an area of dentin where it can be observed a pink physiological development and formation of the root, both discoloration (. Fig. 9.7d), it indicates that a remaining dentin layer of less than 0.5 mm exists, probably associated with on apical and lateral direction. To restore a fractured tooth, the first step is to take a den- clinically undetected microscopic pulp exposures. Therefore, tal radiograph of the area to identify any nonclinically visible this region must be covered with a thin layer of calcium fractures lines. If nothing abnormal was found, it is neces- hydroxide cement to stimulate the formation of reactionary sary to verify if any  pulp exposure had happened. On the dentin. cases of pulpal exposure, it is necessary to decide which procedure is more recomended:  pulp capping, pulpotomy, or 14.6.3.5  Trans-surgical Restoration pulpectomy (details on 7 Chap. 9). On the case of fractured On the cases of fractured teeth, many times, the margin of tooth with incomplete apex but recent pulpal exposure, a the fractured area is located below the edge of the free gindirect pulp capping can be performed with calcium hydrox- giva. On those cases a surgical access through a gingival flap ide powder and calcium hydroxide cement. However, there is usually necessary to expose the fracture margin, allowing are no objective criteria to determine the degree of contami- the correct restoration (. Fig.  14.53a–l). After the access, it nation of an exposed pulp, so the symptoms are the most must be evaluated if the biologic width was invaded. On important aspect [3]. If the direct pulp capping is performed positive cases, if the invasion is small and it is only restricted without previous curettage, the risk of remaining bacterial to the lingual side, a small osteotomy can be performed to contamination is greater, and the pulp must be thoroughly recover the biologic width. However, if a fracture below the  

 

 

 

 

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539 Composite Restoration on Anterior Teeth

alveolar bone crest has occurred on the labial side or the invasion of the biological width happened on the proximal area or on the labial surface, the osteotomy will lead to a change of the gingival position on the labial surface, resulting

in esthetic problems. On those cases, an orthodontic extrusion is required (. Fig. 14.54a–o). It can be performed with fixed or removable orthodontic appliances. However, it is recommended to perform a weekly supracrestal fiberotomy,  

a

b

c

d

e

f

..      Fig. 14.52  Restoration of a fractured tooth associated with a glass fiber post and silicone index. a shade determination; b restoration wax-up in a plaster model; c application of silicone on the model; d removal of the labial side of the index; e preparation of root canal; f fitting test of glass fiber post (Whitepost – FGM) and the silicone index; g bevel on the enamel margin; h protection of the adjacent teeth with PTFE strip and acid-etching; i rinsing; j drying the canal with an absorbent paper points; k application of the dual-cure adhesive system Futurabond U (Voco) with a disposable applicator (Cavibrush, FGM); l application of the silane over the post; m application of the dual-cure resin cement directly inside the root canal (Bifix QM, Voco); n post

insertion inside the canal; o light-­curing after excess removal; p lingual surface of the restoration performed with enamel shade composite (Amaris, Voco, shade TN) using the silicone index; q placement of the matrix and wedge to restore the proximal surface; r proximal surfaces restored; s dentin shade composite inserted reproducing the dentin mamelons and the incisal opaque halo; t high-translucency composite applied between the mamelons; u insertion of a layer of enamel shade translucent composite, followed by an opaque tint creating the white areas scattered irregularly with a disposable applicator, an attempt to simulate the white fluorotic spots on the adjacent tooth; v, w application of the last increment of enamel shade composite; x final result

14

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g

h

i

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..      Fig. 14.52 (continued)

541 Composite Restoration on Anterior Teeth

o

p

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u

v

..      Fig. 14.52 (continued)

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w

x

..      Fig. 14.52 (continued)

a

b

c

d

14

..      Fig. 14.53  Trans-surgical restoration. a, b Fracture bellow the gingival margin; c incision to provide access; d open flap; e rubber dam isolation; f acid-etching; g application of the adhesive system; h

application of the composite; i contouring of the composite surface with a flat brush; j finished and polished restoration; k flap repositioned and stitched; l final result after 2 weeks

543 Composite Restoration on Anterior Teeth

e

f

g

h

i

j

k

l

..      Fig. 14.53 (continued)

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C. R. G. Torres and R. F. Zanatta

where a scalpel blade is used to cut the supracrestal connective tissue fibers around the tooth, avoiding the bone formation as the tooth is extruded. When a partially erupted anterior tooth suffers a fracture, the lesion may apparently invade the biologic width, which is still not defined. When that happens, it can be advantageous

to wait for the end of the tooth eruption and just then to make the final restoration. Many fractures with invasion of the  biologic width, with  the passing of time, become fractures without invasion. In the meantime, the tooth could be maintained without restoration, if the patient does not present sensitivity, or with a temporary restoration, even with

a

b

c

d

e

f

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..      Fig. 14.54  Treatment of a fracture with pulpal and periodontal involvement. a, b Fracture of tooth 21; c, d views of the fragment showing the fracture below the CEJ; e fragment fitting test showing the space loss due to the migration of the adjacent tooth; f, g orthodontic movement with a removable orthodontic appliance to recover the space; h open flap to perform a small osteotomy on the lingual surface, allowing the positioning of a No. 212 clamp below the

fracture margin; i rubber dam isolation; j fitting test of a glass fiber post; k as the fragment adaptation to the remaining tooth structure was very poor, it was chosen to perform a direct restoration. Before stitching the flap, the restoration was finished and polished. l flap repositioned and stitched; m, n orthodontic extrusion to recover the biological width; o final result

545 Composite Restoration on Anterior Teeth

g

h

i

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l

m

n

..      Fig. 14.54 (continued)

14

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C. R. G. Torres and R. F. Zanatta

o

..      Fig. 14.54 (continued)

invasion of the biologic width. This can avoid the children undergo unnecessary surgical procedures, which may cause psychological traumas for the rest of the life [3]. >> When a partially erupted anterior tooth fractures, the lesion may apparently invade the biological width, which is still not defined. When that happens, it can be advantageous to wait for the end of the tooth eruption and just then to make the final restoration. Many of them, with the passing of time, become fractures without invasion.

14

To perform the rubber dam isolation, due to the large difference in the bone crest level position between the labial and lingual surfaces, is frequently necessary to bend the lingual jaws of the No. 212 clamp downward. For that, the technique described in the . Fig. 7.12 can be followed. Although to perform the finishing and polishing procedures immediately after the end of a composite restoration has its disadvantages, and should be delayed on normal situations, it must be done at the same appointment on the cases of trans-surgical restorations, allowing the healing of the gingival tissue. After the end of polishing, the area must be copiously irrigated with saline solution to remove any residues and the flap pressed in position for 5 min. Then, the flap is stitched and the region protected with a periodontal dressing [3]. The patient must receive analgesics, and an ice pack should be applied on the surgical area (side of face) during the first 10 min.  

14.6.3.6 

Reattachment of Fractured Tooth Fragments

When a dental fracture occurs, despite the involvement of the pulp and/or periodontium, the best situation is when the patient was capable to recover the dental fragment. This simplifies the restoration of the esthetic and function through a reattachment procedure. It has as advantages a better esthetic result and function, besides this treatment  last longer than direct composite restorations. In addition, the procedure is simpler and faster than direct or indirect restorations. For the patients, there is a positive emotional factor, since they do not feel mutilated with the loss of part of his tooth. However,

the reattachment is not indicated on the cases of largely restored tooth and less indicated when there is a shade contrast between the fragment and the remaining tooth structure or with the adjacent teeth. The esthetic result will also not be ideal when the remaining tooth structure suffered color changes due to intrapulpal bleeding that happened due to the trauma [3]. After the traumat, the patient should be instructed to maintain the toooth fragment inside, water to avoid its dehydration, until the dental apointment . The first step is to perform the prophylaxis of the dental fragment and remaining tooth structure and do the shade selection. This is important to choose the proper shade for the resin cement or flowable composite that is required for the bonding procedure [3]. The fractures with supragingival margins may be treated with the rubber dam or cotton roll isolation [3]. However, on the subgingival fractures, the use of rubber dam isolation is mandatory [3]. When necessary, a No. 212 retraction clamp can be placed, stabilized with low fusing compound or gingival barrier to avoid its movement during the treatment. The fragment must be fixated to the heated tip of gutta-percha or low fusing compound stick, in a way to allow  its manipulation. The adaptation of the fragment to the remaining tooth structure must be evaluated (. Fig.  14.55a–i). At this moments, the correct fitting position to adapt the fragment should be memorized, training how to place in at the moment of the bonding procedure [3]. It must be evaluated if any tooth movement happened in the meantime between the trauma and the dental appointment, which would close the space for the fragment fitting, being required a previous orthodontic recovery of the lost space. It must also be analyzed if the gingival tissue grown and covered the margins of the fractured area. If there is any difficulty to correctly place the fragment in the desired position, it is possible to prepare a positioning jig [3]. For that, the fragment should be provisionally stabilized in position with composite, without adhesive application, which is light-cured. Over the incisal edge of the fragment and the adjacent teeth, a water-soluble lubricant is applied, such as a glycerin gel. Self-curing acrylic resin is applied over the lubricated area using a brush, which is first soaked in monomer and dipped in the polymer. After the curing, a positioning jig is obtained and can guide the definitive seating. The fragment is then removed and cleaned and receives the adhesive procedures. The jig may also be made with a putty viscosity silicone impression material. When a layer of calcium hydroxide cement is applied as a liner on the remaining tooth structure, this additional volume will impair the fragment adaptation. On this case, an internal space needs to be created in the fragment by cutting the dentin in this region. In some cases, the fracture happens without any tissue loss, and the fragment adapts perfectly to the remaining tooth structure. On those cases, the reattachment may be performed only with the adhesive system (. Fig. 14.55a–i). After prophylaxis of fragment and remaining tooth structure, the proximal surface of the adjacent teeth must be protected with a polyester or PTFE strip. Then, the acid etching of the remaining  

 

547 Composite Restoration on Anterior Teeth

tooth structure and the fragment is performed, followed by blot drying and application of the adhesive system. The acid is applied first over the enamel and then over the dentin. If a liner was applied, the acid should not be applied over it. Preferably a total-etch two-bottle and two-step adhesive system, with a primer and adhesive separated, should be used. After the acid etching, the primer must be applied to both structures (remaining tooth and fragment), followed by gently airstream to leave thin coat and evaporate the ­primer’s solvent. Then, the adhesive (which has no solvents)

is applied, and the fragment is taken in position. While held firmly, the excess of adhesive is removed with an airstream or brush, followed by light-curing for 40 s from the labial side and for 40 s more seconds from lingual side. The gutta-­percha or compound stick is removed. If a total-etch one-bottle system is used, it would not be possible to remove the solvent with airstream before bonding, without removing the necessary adhesive for the reattachment of the fragment, so the solvent would be trapped inside the adhesive interface creating weak areas.

a

b

c

d

e

f

..      Fig. 14.55  Fragment reattachment procedure using only an adhesive system. a Initial aspect; b fitting test of the fragment adaptation showing a perfect match; c prophylaxis with pumice; d acid-etching of the remaining tooth structure; e acid-etching of the

fragment; f, g application of a total-etch two-bottle and two-step adhesive system (primer + adhesive); h reattached fragment; i final result

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C. R. G. Torres and R. F. Zanatta

g

h

i

..      Fig. 14.55 (continued)

14

a

..      Fig. 14.56  Fragment reattachment procedure using resin cement. a Initial aspect; b rubber dam isolation; c fragment fixation in a low fusing compound stick; d fitting test of the fragment showing defective adaptation due to the loss of structure; e, f acid-etching; g, h application of the adhesive system; i dual-cure resin cement applied

b

(RelyX ARC, 3M/ESPE); j reattachment with resin cement; k preparation of a double bevel on the interface with round diamond point to mask the interface; l acid-etching on the area beveled area; m Application of the adhesive system; n placement of a composite on fracture line; o result after 1 week

549 Composite Restoration on Anterior Teeth

c

d

e

f

g

h

i

j

..      Fig. 14.56 (continued)

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C. R. G. Torres and R. F. Zanatta

k

l

m

n

o

14

..      Fig. 14.56 (continued)

However, on most of the cases, the fragment does not fit perfectly to the remaining tooth structure, and there is a loss of tissue on the fracture line. On those cases, a material with stronger mechanical properties should be used to fill the gaps, such as resin cements (. Fig. 14.56a–o) or flowable composites (. Fig. 14.57a–n). The adhesive system selected is used following the manufacturer’s recommendations, similarly to an adhesive cementation of an indirect restoration. The adhesive system is applied, followed by a gently airstream to promote the solvent evaporation and leave a thin coat. In general, it should not be light-cured, in order to not adversely affect the  

 

fragment fitting. The resin cement or the flowable composite resin is applied on the fragment, which is taken into position. The excess is removed with a brush and dental floss, followed by light-curing using a high-output light-­curing unit. On most cases, there is no need to use dual-cure resin cement, because the labiolingual dimensions of the crowns of anterior teeth allow proper polymerization by the light transmitted through the tooth structure. However, depending on the fracture location, on areas where the light cannot reach, such as on subgingival fractures, dual-cure adhesive and resin cement must be selected. On cases of large loss of tooth structure at the inter-

551 Composite Restoration on Anterior Teeth

face, the cement shade may not be adequate to mask the cement line. On those cases, the double bevel can be performed on the interface using a round diamond point, which will simultaneously produce bevels on the fragment and the remaining tooth structure. The groove produced is restored with a composite with proper shade and translucency (. Fig. 14.56j–n). On cases of dental trauma, when the fracture line extends beyond the alveolar crest on the region of the proximal surfaces, the most indicated procedure is the orthodontic extru 

sion to recover the periodontal biologic width. However, on cases where the fragment is kept in position and  holds the gingival tissue, instead of immediately removing the fragment, it is possible to make a temporary reattachment, according to what is shown in . Fig.  14.58a–e. This allows maintaining the smile esthetic during the orthodontic extrusion or may reduce or eliminate the need for periodontal surgery on the cases of partially erupted tooth, besides to simplify endodontic treatment whenever necessary.  

a

b

c

d

e

f

..      Fig. 14.57  Fragment reattachment procedure using flowable composite. a Initial aspect; b shade determination; c Rubber dam isolation; d fitting test of the fragment; e, f acid-etching; g, h application of Solobond M (Voco) adhesive system; i flowable composite

applied (GrandioSO Heavy Flow – Voco); j application of composite on the fragment; k fragment reattachment; l light-curing; m final aspect with the tooth dehydrated because of the isolation; n result after 1 week

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g

h

i

j

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l

m

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..      Fig. 14.57 (continued)

553 Composite Restoration on Anterior Teeth

a

b

c

d

e

..      Fig. 14.58  Oblique fracture below the alveolar crest. A temporary reattachment was performed before the endodontic treatment and orthodontic extrusion. a Fractured tooth with the fragment in position; b double bevel on the interface; c acid-etching; d application of the

adhesive system with primer and adhesive separately (Solobond Plus – Voco); e fragment reattached and composite restoration of the lost structure

Depending on the fracture line location, an intraradicular post can be used for retention ( . Fig. 14.59a–l). The indication of intraradicular posts is related to the dimensions of the fractured area and the overbite. The larger is the fractured area and/or the deeper is the overbite, the higher will be the indication of a post to improve the retention of the fragment. They are only indicated in the cases of large fractured areas. Non-vital tooth with transverse fracture including the entire clinical crown, requires retention and stabilization provided

by the intraradicular post [3]. When large fractures occur on teeth with a deep incisor overbite and strong contacts of disocclusion guides on the incisors, it is also advisable to use a post; while on a patients with anterior open bite or minimum incisor overbite, the post might not be necessary. For transverse fractures located between the medium and incisal third of the crown, the post is also not indicated. On cases of oblique fractures, the use of a post for retention is also not required, because there is a large surface area on the fracture

 

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line available for bonding [3]. When the fracture involves two-thirds or more of the clinical crown and the fragment was lost, a full-crown restoration is indicated, while on the other situations, a direct composite restoration can be performed [3]. It is important to remember that the post does not increase the fracture strength of the tooth, more than the adhesive composite restoration by itself, promoting only the retention [3, 4]. Patients with deep incisor overbite, when the

edge of the lower incisors touch the cervical third of the lingual surface of the upper incisors, as well as with sleep bruxism or clenching while awake, have not a good prognosis when direct restorations or reattachment is performed. Large bevels around the whole fractured area can be performed to increase the retention, and occlusal splints are recommended to protect the restorations during the night. The patients with wear facets are not recommended for direct restorations or

a

b

c

d

e

f

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..      Fig. 14.59  Fragment reattachment procedure using intracanal glass fiber post. a Initial aspect; b fragment fitting test; c internal cleaning of the fragment, creating space for the glass post; d acid-etching; e application of a dual-cure adhesive system inside the canal and on the remaining tooth structure with a disposable applicator; f application of

the adhesive on the glass fiber post (Whitepost DC, FGM); g light-curing of the resin cement after post cementation; h fragment fitting test; i acid-etching of the fragment; j application of the adhesive system; k the resin cement was applied inside the crown and then it was placed in position; l final result

555 Composite Restoration on Anterior Teeth

g

h

i

j

k

l

..      Fig. 14.59 (continued)

fragment reattachment. Those signs suggest extreme function or parafunction, which will produce severe stress over the restorations [3]. If the fragment is stored dry after the fracture, before the dentist appointment, it becomes dehydrated and whiter than the remaining tooth structure. After the reattachment, it can rehydrate and recover its natural shade after some days. However, some fragments take some months to recover the original color, while others will never recover to return to the original appearance. Therefore, the tooth must preferably be kept immersed in water after the fracture [3]. After reattach-

ment, the patient must be advised to avoid using this tooth for biting and cutting hard food, as well as to avoid any habits that may produce high level of stress over the fragment and displace it, such as tearing into packaging with teeth, pencil chewing, chewing ice, and using tongue piercings [3]. Mouth guards must be used when playing any contact sports, as well as occlusal splints are recommended in case of bruxism. The patient must return to the office for periodic visits after 1 week, 1 month, and then each 6 months after fragment reattachment, to analyze the pulp vitality, perform periodontal probing, and analyze the color of the fragment and remaining

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tooth structure, as well as of the composite or cement used in the bonding interface [3]. Pulp and periodontal complications are common after a traumatic accident and clinical evidences can appear just after some time. The radiographic control of the traumatized teeth is required due to the possibility of internal and/or external root resorption, which may appear in the radiographic image only after a long period of time.

14

width-to-length ratio. On median diastemas, close to 2 mm, besides adding composite to the both adjacent teeth, it may be convenient to make enameloplasty on the distal surface these teeth, slightly increasing the mesial surface of the other adjacent teeth, obtaining a better distribution of the space. Large diastemas must be treated associating orthodontic movement with composite restorations [35]. When patients with large median diastemas (larger than 3 mm) are treated only with composite buildups, the restored >> After reattachment, the patient must be advised to teeth will be larger than the natural teeth can be. For examavoid using this tooth for biting and cutting hard food, ple, the central incisors are rarely larger than 9.5  mm. If a as well as to avoid any habits that may produce high patient with incisors of 9.5 mm has a 3 mm width diastema level of stress over the fragment and displace it, such and the dentist fills half of this space with composite, the final as tearing into packaging with teeth, pencil chewing, dimensions will be 11 mm width. This will break the correct chewing ice, and using tongue piercings. Mouth width-to-length ratio, creating a non-esthetic result. In genguards should be used when playing any contact eral, the apparent width of upper anterior teeth should not be sports, as well as occlusal splints are recommended in higher than 80% of its length. This situation would require a case of bruxism. reduction of at least 1 mm on the distal surface of both central incisors, which would result in dentin exposure on the 14.6.3.7  Recontouring Teeth with Direct proximal surfaces. On those cases, the orthodontic treatment Composite Buildups is essential, promoting the redistribution of spaces, reducing Some patients present anomalies of tooth formation which the diastemas between the central incisors, and creating results in abnormal shape or size, such as misshapen peg-­ spaces between them and the lateral incisors, which could be shaped maxillary lateral incisor, microdontia, dens in dente, closed by adding the composite on the mesial surfaces of the and Hutchinson’s incisors. Others have generalized diaste- lateral incisors [27]. mas due to tooth size and arch length discrepancies or localIt is very important to measure the diastema size to plan ized diastemas, such as the median diastema [36]. Despite the final width proportion among the anterior teeth. For that, the reason, those disturbances may severely compromise the it can be used a plaster study model and a bow compass with esthetics of the smile. In some cases, the orthodontic treat- two needle points, or a Chu’s Aesthetic Gauge to analyze denment may completely solve the problem. However, in other tal proportion, as it has already been described. If the teeth situations, only an artificial recontouring may be the solu- that are forming the diastema present an incorrect width-to-­ tion. The adhesive direct composite restorations are an excel- length ratio, with teeth narrower that could be, the diastema lent alternative to the full crowns, because they are closure may be performed without any problem. If the teeth conservatives and can reshape the teeth simply by adding are already larger than the ideal, to increase even more its material, without requiring any cutting of the intact tooth width would result in a great esthetic problem, and it would structure. be better to redistribute the spaces with orthodontic treatThe median diastema, located between the central inci- ment. sors, is the most frequent one. Its etiology was generally To preserve the anatomic proportions, sometimes when related to the presence of enlarged labial frenum, which the width of anterior teeth needs to be enlarged with comcould adversely affect the normal closing of the space between posite buildups, it may be also necessary to increase its the teeth. Other causes include anodontia, very small or length. If the occlusal relations and the facial appearance badly formed teeth, and tooth size discrepancy, which is a allow (see 7 Sect. 1.3.4 in 7 Chap. 1), the adequate dental disproportion among the sizes of upper and lower anterior length may be obtained adding composite on the incisal teeth (Bolton’s discrepancy), supernumerary teeth, and edge. The width-to-length ratio can also be improved through hereditary factors. The diastemas may also result from other a gingival periodontal surgery, increasing the clinical crown problems such as tongue thrusting, periodontal disease, or length [35]. It is advisable to previously simulate the changes posterior bite collapse. The diastemas should not be closed making a diagnostic wax-up on a plaster model and a mockbefore to diagnose and treat its causes [31]. The occlusion ­up restoration, applying the composite on the teeth without any previous adhesive procedure. This will give the patient an must be carefully evaluated. When closing diastemas is important to keep an adequate idea about how the future restoration will look like, and if width-to-length ratio to obtain an esthetically pleasant final that result is pleasant to him. The bow compass with two results [35]. According to the size, the diastemas can be clas- needle points can be used to analyze the mock-up dimension sified into three types, which are small (space smaller than 1 and do any correction [27]. For the restorative procedure, after shade determination mm), medium (space from 1 to 2.5 mm), and large (space larger than 2.5 mm). For the small diastemas, a little amount and prophylaxis of the teeth surface, the rubber dam isolaof composite can be applied on both adjacent teeth, until the tion can be performed. Ligatures with dental floss can be total closing of the space, producing little interfering on the required to provide a good retraction of the rubber dam  

 

557 Composite Restoration on Anterior Teeth

edges. As an option, cotton roll isolation with retraction cord, associated or not with a cheek retractor, can also be performed. When both teeth adjacent to the diastema will be restored, the first restoration must be finished before starting the second one (. Fig. 14.60a–o) [27]. First of all, the adjacent tooth to the one that will receive the first restoration must be protected with a PTFE strip. Then, the acid etching  

of the enamel is performed for 15 s and the surface is rinsed. The acid etching must be extended to the middle of the labial and lingual surfaces, from the gingival to the incisal third of the crown. The restoration will cover about one-third of the labial and lingual surfaces. It is important to be sure of not covering with composite any non-etched enamel. Any etched enamel areas that remain uncovered by adhesive and com-

a

b

c

d

e

f

..      Fig. 14.60  Diastema closure. a Initial aspect; b shade determination; c protection of the adjacent tooth with PTFE strip and acidetching; d rinsing; e drying with airstream; f application of the adhesive system; g light-curing; h application of enamel shade composite (Amaris – Voco, shade TN) with the matrix in position, stabilized with the index finger; i matrix closed over the labial surface for light-curing

the increment; j measurement of the tooth dimensions with a bow compass with two needle points; k analysis the space left for the restoration of the adjacent tooth; l acid-­etching; m application of adhesive; n application of the last composite increment, closing the matrix over the labial surface; o final result

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C. R. G. Torres and R. F. Zanatta

g

h

i

j

k

l

m

n

14

..      Fig. 14.60 (continued)

559 Composite Restoration on Anterior Teeth

should be taken not to pulling the strip too much, which may result in the undercontoured restoration. Most of the small diastemas may, in many cases, be successfully closed only using enamel shade composites, which are more translucent [35]. However, larger diastemas require the use of an opaque dentin shade, to block the dark background of the mouth. On those situations, the first increment of dentin shade composite may be placed until it fills approximately half of the labiolingual distance. The composite is light-cured, and a new layer is applied, using enamel shade material. The matrix is closed over the labial tooth surface, and the light-curing is performed through the strip. The first restoration is finished and shaped until obtaining the correct anatomical size and shape [35]. The dimensions can be evaluated with a bow compass to determine if they are correct (. Fig. 14.60j, k).

o

..      Fig. 14.60 (continued)

 

posite will remineralize after the contact with the saliva [27]. The enamel may be dried with an airstream, since there is no exposed dentin, observing the white-opaque appearance, showing it was correctly etched. If an adhesive with separated primer and bond bottles is selected, there is no need to apply the primer [31]. However, if the enamel is left wet, the primer application is important, since the bonding resin is hydrophobic. It is important to use a composite with enough physical properties to bear the masticatory forces to which the restoration will undergo, such as the microhybrid, nanohybrid, or nanofilled. In the past, due to the insufficient polishing provided by the hybrid composite, it was recommended to use this material to restore only the lingual side, being covered by a microfilled material on the labial surface. This procedure is no longer necessary with the modern composites, because they provide good polishing and esthetics associated with proper mechanical properties. Before applying the composite, a polyester strip may be contoured drawing it over the round back end of a clinical tweezer and placed in position. The bow compass with two needle points is used to measure the mesiodistal dimensions, to guarantee the symmetry of the restored teeth. If one tooth is larger than the other, this discrepancy can be compensated with the restoration [31]. The restoration must start below the gingival margin to create a natural contour and ensure adequate gingival embrasure and emergence profile [31]. If the cotton roll isolation is being used, a gauze bandage square can be placed over the tongue to prevent undesired contamination of the area with saliva [31]. The polyester matrix strip must be inserted into the gingival sulcus between the interdental papilla and the tooth. It is kept in position with a pad of the index finger, pressing the lingual aspect of the strip toward the remaining tooth structure, while the labial portion is reflected away. Wedges are, generally, not recommended because they could create an inadequate emergence profile [31]. The composite is applied with a hand composite filling instrument, pressing it toward the lingual side to ensure that it will reach the lingual surface. The matrix is gently closed on the labial side, pulling more the gingival edge of the strip to prevent overhangs (. Fig. 14.60h, i). Care  

Tip

Wedges are not recommended when closing diastemas with composite because they can create an inadequate emergence profile.

After that, the restoration of the neighbor tooth is started. The proximal contact may be obtained by displacing the already restored tooth with the thumb and the index finger slightly toward the distal side, while the matrix is maintained in contact with the adjacent restoration. The polishing is only performed after the second restoration is finished. The continuity of the cervical region of the restoration with the tooth structure must be perfect, without overhangs. It is evaluated by passing a dental floss embracing the tooth on the proximal surface, moving it cervicoincisally. It should not shred and fray, which would indicate the presence of defective contour. Any overhang must be completely removed using abrasive finishing strips. The occlusal contact during centric occlusion (CO) and disocclusion guides must be evaluated and adjusted [31]. On the case of medium and large diastemas, the palatal silicone index technique, as already described, may simplify the procedure to be performed, as it can be observed in . Fig. 14.61a–q. . Figures  14.62a–d′ and 14.63a–i show clinical cases of dental recontouring of peg-shaped maxillary lateral incisor using palatal silicone index, similarly to what was already been described for fractured and caries-affected teeth. In . Fig. 14.62a–d′, the palatal silicone index was made directly in the mouth over the old unsatisfactory restorations.  

 

 

14.6.4 

The Use of Color Modifiers

The color modifiers, also referred as characterization material or tints, are flowable composites with different colors and opacities, intended to be used as an intermiediate layer between the adhesive coat and the restorative composite or between the composite layers (. Fig. 14.64). Before its use, it  

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C. R. G. Torres and R. F. Zanatta

should be applied over a mixing pad and mixed with a hand instrument with small circular movements. If it is too viscous, it can be mixed with clear liquid resin (untinted), supplied by some manufacturers, or with the adhesive of a two-bottle (primer and bond) fourth-generation adhesive system, which does contain solvents in the composition. It must be applied the thinnest layer possible, enough to produce the optical effect desired, such as 0.25  mm or less,

because they have fewer inorganic fillers and more pigments, with reduced mechanical properties. It is applied with a thin brush in a way that, at the end, it would not be possible to observe the marks left by the bristles. That would indicate that the material is still too viscous [27]. On the case of teeth with darker shades on the cervical region, a honey yellow or light brown tint can be applied over the adhesive coat, producing a gradient of shades,

a

b

c

d

e

f

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..      Fig. 14.61  Diastema closure using a diagnostic wax-up and silicone index. a–c Initial aspect; d aspect after dental bleaching; e waxup on the plaster model; f acid-etching; g etched enamel with white-opaque appearance after the drying with air steam; h application of the adhesive system; i silicone index fitting test; j index in

position with enamel shade composite to restore the lingual surface (Opallis – FGM, shade E-Bleach); k lingual surfaces restored; l application of the opaque dentin shade composite (Opallis shade D-Bleach); m application of enamel shade composite; n aspect after polishing; o final result. p, q smile before and after the treatment

561 Composite Restoration on Anterior Teeth

g

h

i

j

k

l

m

n

..      Fig. 14.61 (continued)

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C. R. G. Torres and R. F. Zanatta

o

p

q

..      Fig. 14.61 (continued)

14

starting from the cervical area and extending 1–2 mm incisally. The tint is light-cured and covered with dentin and enamel shade composites. After polishing, the yellow background will be seen through. The final shade of the restoration will depend on the amount and chroma of the tint applied, as well as the thickness of the composite layer applied over it. The tint color may be changed by mixing a little amount of white tint or a clear liquid resin [27]. The white tint is generally referred to simply as opaque, because it is used mainly to mask or cover dark backgrounds, such as metal or sclerotic dentin. On most cases, a highly translucent incisal edge may be restored associating opaque and translucent shades of composite. However, if a highly translucent composite is not available and the translucency of the incisal edge is intense, with a grayish or bluish appearance (due to opalescence), a gray, blue, or violet tint or a mixture of those can be applied on the region to create the desired effect. They can be used between the tooth and the composite, or between the layers of the composite. First of all, it is necessary to analyze the characteristics of the intact adjacent teeth to be recreated. It must be done before the rubber dam isolation, because the drying can adversely affect the observation of the details. The

tint is applied as a thin layer with a brush on the desired areas and then light-cured [27]. The honey yellow, light, and dark brown tints, besides being used to recreate the cervical shade, can also be used to replicate the dark grooves on the posterior teeth (. Fig. 15.17 t, u ) and enamel cracks. On cases of teeth with yellow areas due to the counter-opalescence, the yellow tint may also be used. Hypomineralized spots may be created with white opaque tints applied over the dentin shade layer or between  the enamel shade composite (. Fig.  14.52a–x). Another possibility to simulate the hypomineralized spots consists of making small cavities on selected areas, about 0.5 mm deep, on the already finished and polished surface of the restoration, with a round diamond point, and applying a little amount of the opaque tint, covering it with the same enamel shade composite previously used [27]. The opaque tints can also be used to recreate the opaque halo on the incisal edge and mask a dark background, such as on darkened teeth or metallic restorations (. Fig. 15.16f) and sclerotic dentin, or reduce the translucent aspect of some composites [27]. To simulate enamel cracks on the restorations, the last layer of enamel shade composite is applied but not light-­cured. A 10  

 

 

563 Composite Restoration on Anterior Teeth

a

b

c

d

e

f

..      Fig. 14.62  Recontouring of peg-shaped maxillary lateral incisors using palatal silicone index prepared over the old restorations. a Unsatisfactory restorations on teeth 12 and 22. Shade determination; b preparation of the silicone index using putty silicone material over the old restorations; c old restoration removed from tooth 12; d rubber dam isolation and test of the silicone index; e protection of the adjacent teeth with PTFE strip and acid-etching; f rinsing; g drying with the stream. A white-opaque appearance is observed on the etched area; h application of the adhesive system; i light-curing of the adhesive; j application of enamel shade composite on the index (Z350 XT – 3M/ESPE); k lingual surface restored; l restoration of the proximal surfaces using matrix strip and wedge; m placement of opaque composite for the incisal opaque halo; n application of opaque

composite to restore the dentin lobes; o application of highly translucent composite between the dentin lobes to reproduce the translucency of the incisal edge; p application of a body opacity composite over the remaining tooth structure and the dentin shade composite; q application of enamel shade composite and contouring with a flat brush; r immediate result; s finishing with polishing disc (Super-Snap, Shofu); t, u preparation of grooves between the lobes with fine grit diamond point (No. 392EF, Komet); v creation of scratches to simulate the perikymata using a diamond point moved very slowly mesiodistally; w polishing with felt disc (Diamond Flex, FGM) and polishing paste (Diamond Excel, FGM); x, y final result of the tooth 12; z initial aspect of tooth 22; a′ initial aspect of the tooth 22; b′, c′ final result of the tooth 22; d′ final aspect of both restorations

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C. R. G. Torres and R. F. Zanatta

g

h

i

j

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14

..      Fig. 14.62 (continued)

565 Composite Restoration on Anterior Teeth

o

p

q

r

s

t

u

v

..      Fig. 14.62 (continued)

14

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C. R. G. Torres and R. F. Zanatta

w

x

y

z

a’

b’

c’

d’

14

..      Fig. 14.62 (continued)

567 Composite Restoration on Anterior Teeth

× 4 mm piece of thin polyester strip is cut and inserted into the composite, following the direction of the crack that is desired to simulate. The light-curing is performed, and the stripe is removed, leaving a small gap. This space is filled with the selected tint, the excess is removed, and the light-curing is performed [27]. On the case of a dark yellow background, the blue color tint, which is complementary color of yellow, can be applied over to reduce the yellowish aspect [31]. In Class IV restorations, it is possible to apply a little amount of white opaque

tint between the lobules made with dentin shade composite, in the incisal area, to highlight this detail [19, 38]. Another possibility to recreate the counter-­opalescence is to apply a small amount of the white opaque tint on the end of the dentin lobules, covering them with naturally opalescent composite. There also some opaque tints with shades following the VITA Classical shade guide, such as the A1 and A3 from Kolor + Plus (Kerr), which may be used to bring the background shade closer to the desired shade for the final restoration (. Fig. 17.6h, i).  

a

b

c

d

e

f

..      Fig. 14.63  Dental recontouring of peg-shaped maxillary lateral incisors using diagnosis wax-up and palatal silicone index. a Initial aspect; b wax-up on a plaster model; c removal of the old restoration and placement of gingival retraction cord; d fitting test of the silicone

index; e application of enamel shade composite on the index; f finished lingual surface; g application of dentin shade composite creating the dentin lobules; h immediate result; i final result after polishing. Clinical case performed by Dr. Taciana M. F. Caneppele

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g

h

i

..      Fig. 14.63 (continued)

is the procedure of fine removal of the restorative material, resulting in a very smooth and glossy surface, reproducing the texture of the natural teeth and giving comfort to the patient.

14

14.6.5.1 

..      Fig. 14.64  Example of color modifier (Kolor + Plus – Kerr)

14.6.5 

Finishing and Polishing

The finishing and polishing represent the last ones but extremely important steps of a composite restoration. The finishing  is the procedure of large removal of restorative material to eliminate excess and overhangs on the margins, improve contour, adjust the occlusion, and produce a ­reasonably smooth surface. On the other hand, the polishing

Finishing

Ideally, no cut or grinding on the restoration should be performed immediately after the light-curing of the final composite layer, because it is not fully polymerized. However, it is sometimes hard to obtain a perfect restoration contour during the incremental composite placement, being necessary some type of finishing. Therefore, to provide the adequate function and comfort for the patient, just the essential adjusts should be performed at this moment. The “dark-curing” of the composite continues for about 24 h after light-curing, when the material reaches its maximum strength [3]. The friction produced by a rotary instrument generates more aggression to a composite recently placed than after the post-­curing.

Finishing is the procedure of large removal of restorative material to eliminate excess and overhangs on the margins, improve contour, adjust the occlusion, and produce a reasonably smooth surface.

569 Composite Restoration on Anterior Teeth

It was proved that the polymerization shrinkage can produce marginal gaps on the tooth-restoration interface. In addition, the use of rotary instruments can generate microfractures on the tooth and restoration margins around the gap, and the residues may penetrate into gaps, creating white lines on the interface. When the dentist wait for a certain period before polishing the restoration, the composite can suffer water sorption and undergo a certain hygroscopic expansion, of approximately 1% by volume, reducing the size or even closing the marginal gaps and the possibility of white lines [3]. The white lines observed clinically are correlated with the rupture of the adhesive bonding and the lack of restoration adaptation to the tooth structure. However, it is important to highlight that, even though the gap may be closed by the water sorption, the adhesive interface will remain broken, allowing marginal microleakage. Other reasons for white lines at the interface are the traumatic finishing and polishing procedure, improper etching and/or adhesive application, and composite polymerization using excessively high-emmitance light-curing units, creating excessive shrinkage stress and not only gaps but also microcracks of the enamel close to the margins [3]. Some studies have shown that delaying the polishing procedure can reduce the marginal microleakage and surface roughness, besides increase the microhardness [18, 20, 44, 45]. However, in the cases where the gingival margin was accessed by retraction clamps or by surgical means, the finishing and polishing must be performed before the removal of the rubber dam [3]. After the isolation removal is important to perform the occlusal adjustment of the restoration, analyzing the contacts in maximum intercuspation and during the excursive movements of the mandible. The presence of the premature contact or interference during the excursive movements may lead to fracture or displacement of the restoration [31]. First of all, the CO contacts must be adjusted, evaluating if the teeth adjacent to that restored are contacting the opposite teeth the same way as before the tooth preparation. The contacts on CO must be marked with one of the two colored sides (e.g., black) of an articulating paper, placed facing the restoration. If only the restoration contacts the opposite teeth and the adjacent teeth do not show any contact, the composite must be grinded and the contact evaluated once again. If necessary, the adjustment must be repeated until all the adjacent teeth that had contact before the preparation start to contact once again. Then, the second colored side (e.g., red) is placed facing the restoration, and the patient is asked to perform lateral and protrusive movement on the mandible. The restored tooth may participate on the disocclusion guides but the stronger contacts should be, whenever possible, distributed on the intact neighbor teeth [3]. If the anterior disocclusion guide is happening only over the restored teeth, it must be adjusted until the adjacent teeth start to participate.

14

If the restored tooth does contact or participate of the disocclusion guides with the antagonist teeth on the remaining tooth structure, no contact needs to be left on the restoration. However, if before the restoration the tooth did not do any contact or guides, it must be reconstructed with the restorations and adjusted for not producing interferences during functional movements of the mandible. The stress concentration over a single restoration may result on its fracture or displacement [31]. The entire marginal area of the restoration, at the tooth-­ restoration interface, must be analyzed with an exploratory probe. It has to be moved from the tooth surface to the restoration surface and from the restoration to the tooth, detecting excess or lack of material. The anatomical form must also be analyzed, evaluating the presence of over or undercontour. The proximal surface must be evaluated with dental floss. If it shreds and frays, that will indicate the presence of overhangs or other marginal disadaptations [31]. The dental floss must be placed below the gingival cavosurface angle and pulled incisally on a movement like the one used to polish shoes [31]. Any abnormalities must be corrected by removing or adding composite. It is important to highlight that instruments to be used during finishing and polishing must be adequate to the shape of the surface to be worked, which can be flat, concave, or convex. The marginal overhangs, mainly on the proximal surfaces, may be removed with scalpel blades, such as the No. 11, 12, or 15, moved from the tooth surface to the restoration or following the margin, using gentle cutting movements, keeping the blade laying on the enamel surface as a guide to prevent an over removal [31]. This prevents marginal fractures, cutting small portions at a time. If a large area is intended to be removed with a blade at once, the composite may fracture inside the cavity preparation walls, being required to repair this region adding more material. An irregular gap is created and may allow biofilm growing, as well as residues deposition that can promote marginal staining and the recurrent caries lesion. The No. 12 blade is useful on the proximal areas due to its curved shape and a thin end, making it ideal to remove excesses on the cervical regions (. Fig.  14.48u) [31]. There are also dedicated hand instruments for composite excess removal on the margins, such as the contour carbide carver shown in . Fig. 14.48t. Rotary instruments may also be used to remove excess on the margins, such as the fine grit (average particle size of 25 μm) and extra fine grit (average particle size of 15 μm) diamond points, multi-bladed burs (. Fig. 14.65a, b), or the aluminum oxide mounted stones (. Fig. 4.28a). The shape of the rotary instrument must fit the surface to be worked on. The egg (football) or pointed football-shaped instruments are used on the lingual surfaces, which has a concave contour (. Fig. 14.48s) [31]. Those instruments should be used under air refrigeration from a three-way syringe, in reduced speed, gently pressure, and intermittent contact [2, 3, 31]. The use of air/water spray adversely affects the visualization of details in  

 

 

 

 

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the area to be finished. The thin tip cone-shaped rotary instruments, such as the fine grit diamond points or the aluminum oxide mounted stones, are indicated for difficult access regions as the cervical area and embrasures or flat surfaces (. Fig.  14.39t). On the gingival margin of labial surfaces, the Zekrya gingival protector or similar instrument can be used during the finishing avoiding harming the gingiva (. Fig. 6.16) [3]. The rotary instruments must be used with care in the cervical region, especially on the root surface, to prevent the incorrect and undesired removal of the tooth structure, usually cementum and dentin. During the finishing procedure on the gingival margin, to remove excess of composite, the restoration surface only should be touched with a bur or diamond point, while a mesiodistal swiping movement is being performed. The marginal adaptation must be frequently evaluated with an exploratory probe. If the rotary instrument is activated touching the tooth/root surface without being constantly moved, it can create a defect like a groove on the surface that will require restoration [31]. The difficulty is higher when the overhang is located in a gingival margin of the preparation covered by the marginal gingiva. In an attempt to completely remove the excess, the dentist sometimes grinds the root and creates a step (. Fig.  14.66a, b) [31]. For safely finishing of the gingival margins on that situation, 0.5 mm of the diamond coat can be removed from the tip of the conical-shaped diamond point. For that, the abrasive point is rotated over an abrasive stone until the diamond particles are lost in this area (. Fig. 14.66c). The safe end tip instrument can be used to contour the cervical areas of the restorations. Touching the safe end on the root surface inside the gingival sulcus, it can easily reshape the cervical region without harming the root surface (. Fig. 14.39t) [27]. If the matrix band has been properly placed in the proximal area, there is almost no need to finish or polish the proximal surface of the restoration, because the composite is capable to copy the roughness of the matrix strip. However, if there are cervical overhangs, they must be removed without damaging the proximal contact. For that, the abrasive strip  

 

 

 

14

 

a

should be used with a back-and-forth movement. The abrasive strip has two color-coded abrasive grades per strip, sequenced from dark to light, with the center gapped for easy interproximal insertion. One of the sides has thicker grit for finishing and the other with a thinner grit for polishing (. Fig. 14.67). Different strip widths are available on the market. The narrow ones are indicated in short interproximal areas to improve contour, remove excess, and polish the cervical regions. The wide ones should be used carefully for not removing the contact between the teeth [31]. When passing the strip through the proximal contact areas, gapped center without abrasives can be used without abrading the contacts. When it is necessary to grind the entire proximal surface of the restoration, the abrasive strip must simultaneously touch the labioproximal and linguoproximal external line angles (. Fig. 14.48w). However, if the grinding is required in only one of the external line angles, the abrasive side of the strip must touch the restoration only on that side, pressed over the corresponding smooth surface with one of the hands, while in the opposite side, it is moved away from the tooth with the other hand (. Fig. 14.48v) [31]. Abrasive discs can be used on flat tooth surfaces such as the labial surface and incisal edge (. Figs. 4.30a and 14.62s). The finishing is performed with a more abrasive disc, while the polishing is performed with a sequence of decreasing grit size. They are used dry in low speed and intermittently [3]. In the labial surface of the incisors, the discs are used in the flat area located on the incisal and medium thirds. The cervical third is convex and can be finished with a long conical-­ shaped rotary instrument, such as a fine grit diamond point, multi-bladed bur, or aluminum oxide mounted stone. During the finishing is important to pay attention to the fact that the contour and surface topography of the restoration must be similar to the adjacent or homologous tooth. Young people present an irregular labial surface, showing the developmental lobes. Before polishing, all those details must be reproduced. For that, the tooth must have the essential finishing complete, with the correct crown contour and without marginal excess. Then, diamond points with different shapes are used, depending on the surface characteristics to  

 

 

 

b

..      Fig. 14.65  Rotary instruments for finishing procedure. a Fine grit diamond points of different shapes; b multi-bladed burs (30 blades)

571 Composite Restoration on Anterior Teeth

a

b

c

..      Fig. 14.66  a, b Finishing of cervical restoration with gingival cavosurface angle covered by the marginal gingiva may result on wrong grinding of the root surface, creating a step; c a safe end tip can

be created rotating the tip of a diamond point over a mounted stone, until complete removal of the diamond layer

contact, as brushing strokes, trying to create scratches perpendicularly to the axis of the tooth. If the perikymata of the adjacent tooth or remaining tooth structure are deep, a coarse grit diamond point can be used, while if they are shallow, a fine grit point should be chosen. This procedure can be performed without water spray, allowing the dentist to follow the creation of the scratches (. Figs. 14.38t′, u′ and 14.62v).  

14.6.5.2 

Polishing

Even though it is impossible to obtain a perfectly smooth surface of a restoration inside the mouth, the surface roughness can be gradually reduced using a sequence of abrasive agents, with particles progressively smaller, until reaching the texture of natural enamel. . Figure 14.68 shows the sur..      Fig. 14.67  Abrasive strips face profile of a composite, measured using a laboratory a device called rugosimeter. It has a diamond stylus tip that be reproduced. The two grooves between the developmental does direct contact with the surface and is moved on it, genlobes, on the labial surface of the adjacent intact teeth, can be erating a graphic representation of the surface profile. In this marked with a pencil and reproduced over the restorations graph, it is possible to observe the higher points called peaks [1]. The grooves may be prepared with a thin end conical-­ and the lower ones called valleys. The upper graphic in shaped diamond point, as it is shown in . Figs. 14.38s′ and . Fig. 14.68 shows the surface roughness after the finishing 14.62u. The perikymata may be reproduced by moving a dia- procedure, while the lower shows the roughness after polishmond point over the labial surface in very slow speed, on the ing. It can be noticed that even after all efforts on the polishdeceleration of the handpiece rotation, with intermittent ing procedure, a perfectly smooth surface is not obtained.  

 

 

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..      Fig. 14.68  Surface profile of a restorative composite after finishing and polishing procedures

ROUGHNESS AFTER FINISHING 0.200 mm 0

–0.200 0.25 mm/div

ROUGHNESS AFTER POLISHING 0.200 mm 0

–0.200 0.25 mm/div

14

However, the resulting roughness must come close to the natural teeth, below the visual detection level, and not be noticed when contacting soft tissues, mainly the tongue.

Polishing is the procedure of fine removal of restorative material, resulting in a very smooth and glossy surface, reproducing the texture of the natural teeth and giving comfort to the patient.

also be used. On the other hand, on cases of young patients, where the surfaces have been characterized with grooves or perikymata, the use of discs for polishing would remove the surface details. On those cases, the labial surface should be polished only with a felt discs and polishing paste, resulting in a smooth but not flat surface (. Figs. 14.38v′ and 14.62w). Another possibility to polish irregular surfaces is to use abrasive silicon carbide brushes, which bristles are impregnated with abrasive particles(. Fig . 4.31a – 5 and 6) or abrasive rubber spirall wheels (. Fig. 4.29d). On the cervical region, the polishing can be performed with a thin tip abrasive rubber point or disc, taking care of not creating a flat surface. It can also be used a felt discs with polishing paste (. Fig. 14.39u–w). A study showed that additional polishing with a diamond polishing paste after initial polishing with abrasive discs reduces the surface staining of the composites [17]. When a two-paste polishing system is used, the paste with higher grit must be used first. Then, the surface has to be washed, and then smaller grit one is employed using a clean felt. Some felt discs already come impregnated with abrasive particles and do not require the associated use of a polishing paste. The blunt tips of the abrasive rubber points can be sharpened as shown in . Fig. 4.29. The proximal surfaces can be polished with fine grit abrasive strips (. Fig. 14.44v, w). The lingual surface may be polished  

 

 

The polishing must be performed keeping in mind that surface details created by the finishing procedure should be kept after it. On the case of elderly patients, with a worn and smooth labial surface, the polishing of the flat surfaces can be performed with a sequence of decreasing grit discs. Between each disc, the surface has to be rinsed and dried to remove the residue of the previous abrasive particles [31]. The discs with a smaller diameter (1/2 inch) are ideal for the cervical region, besides accessing better the embrasures and the marginal ridges. The discs with smaller mandrel allow more access and larger abrasive surface, while the ones without a metal center and with elastic silicone shank mount are easier to use. Abrasive rubber discs with a flat surface can

 

 

 

573 Composite Restoration on Anterior Teeth

using abrasive rubber points, felt points with abrasive paste, abrasive silicon carbide brushes  or  abrasive rubber spirall wheels (. Fig. 14.48y, z and 4.29d). If during finishing and polishing procedures hollow spaces appear on the restoration surface, due air bubbles entrapped in the composite or defect of adaptation between the increments, a small round diamond point is used to remove the defective area. The area is acid etched and the adhesive system is applied but not light-cured. The same composite used to do the restoration is applied and light-­ cured. The surface is finished and polished [27]. It is important that all the information regarding shades and brands of composites and tints used for the restoration are registered on the patient’s records. This information will be useful if any repair is required in the future. After ending the finishing procedure, the restorations must be visually analyzed and the margins evaluated with an exploratory probe. The proximal surfaces and the gingival cavosurface angle have to be evaluated with dental floss. The presence of marginal overhangs, white lines at the interface, defective shape and contour, lack of proximal contact, insufficient restorative material on the cavosurface angle, and presence of air bubbles exposed on the surface are evaluated. If there is any problem, it should be immediately corrected [3]. If the restoration is considered adequate, a surface sealing procedure, also known as rebonding, can be performed to seal microcracks on the composite surface generated by the rotary instruments, as well as marginal gaps in the tooth-­ restoration interface produced by the shrinkage stress. For that, acid etching of composite surface and tooth structure 1–2 mm beyond margins is performed for 15 s, which is rinsed with air/water spray and dried with the airstream. The surface sealant is applied, followed by an airstream to produce a very thin coat, which is lightcured for 10 s. This procedure increases the marginal integrity and reduces the composite wear. It may be repeated at each patient return to the dental office, every 6 months or 1 year [3]. The product used for the surface sealing is a dedicated material and is not related with pit and fissure sealants.  

14.7 

Durability and Maintenance of the Composite Restorations

The durability of the composite restorations depends on three main factors: the dentist, the material, and the patient. In relation to the dentist, the correct indication of each restoration technique, the adequate tooth preparation, and the proper use of adhesive system and restorative technique will guarantee a maximum quality esthetic restoration. However, technical failures during the restorative procedure may drastically reduce the durability of the restoration, allowing premature degradation and intense microleakage, leading to postoperative sensitivity and secondary caries lesions. The dentist is responsible to perform

each operative procedure very carefully; paying attention to the technical details [31]. In relation to the restorative material, good quality products correctly indicated will match the efforts and correct technique applied by the dentist, increasing the longevity of the restoration. Material’s characteristics such as mechanical properties and polishability are paramount for the correct indication of each product on each clinical situation. In relation to the patient, factors such as extension of the lesion, static and dynamic occlusion patterns, the dietetic habits, and oral hygiene are very important to determine the durability of the restoration [31]. The larger the preparation, the more critical is the restoration and greater are the chances of failure. People with high consumption of acidic food and beverage, as well as high level of chromogens, or heavy smokers may present faster degradation of the composite organic matrix, as well as very fast staining. The parafunctional habits may also lead to the premature degradation of the restoration due to the great stress they are subjected. The patients must be informed about the etiology of the caries disease and non-carious lesions they may have, and be motivated to practice preventive measurements, including dietary changes, good oral hygiene practices, and periodic visits to a dental clinic. Despite the best material and restorative technique used by the dentist, the long lasting of the restorations will mainly depend on the patient’s oral care. >> Despite the best material and restorative technique used by the dentist, the durability of a dental restorations will mainly depend on the patient’s oral care.

Conclusion This chapter presented all procedures necessary to restore anterior teeth with composite-based materials. The concepts related to shade determination and esthetic analysis were discussed and must be kept in mind, whenever this kind of restoration is planned by the dentist. In relation to the tooth preparation, the maximum preservation of the remaining tooth structure must rule the clinical procedures, but always allowing the best esthetical results to be obtained. The step-­ by-­ step restorative techniques for all classes of cavities were presented here, since selection of appropriated composite, adhesive system application, matrix placement, and incremental technique. For fractured teeth, the diagnosis of the actual conditions and extension of the damage is very relevant, determining the recommendations about the treatments of the pulp and periodontal tissue, when they were involved, or the choice for a fragment reattachment or a full composite restoration. In addition, composites can also be used for recontouring teeth, being an excellent alternative to indirect procedures, since no removal of sound tissue is necessary. However, despite the best dentist’s efforts, the durability of the restoration depends a lot of the patients’ oral habits and hygiene, and they need to be informed about that.

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References

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1. Baratieri LN.  Soluções Clínicas  - Fundamentos e Técnicas. Florianópolis: Editora Ponto; 2008. 2. Baratieri LN, Araujo EMJ. Caderno de Dentística: Restaurações Adesivas Diretas com Resinas Compostas em Dentes Anteriores. São Paulo: Santos; 2002. 3. Baratieri LN, Monteiro Junior S, Andrada MA, Ritter AV. Odontologia Restauradora: Fundamentos e Possibilidades. São Paulo: Santos; 2001. 4. Baratieri LN, de Andrada MAC, Arcari GM, Ritter AV. Influence of post placement in the fracture resistance of endodontically treated incisors veneered with direct composite. J Prosthet Dent. 2000;84:180– 4. https://doi.org/10.1067/mpr.2000.108415. 5. Barcellos DC, Palazon M, Pucci CR, Gomes Torres CR, de Paiva Gonçalves SE. Effects of self-etching adhesive systems used in the dental modelling technique on the cohesive strength of composite resin. J Adhes. 2011;87:154–61. https://doi.org/10.1080/00218464.2 011.545340. 6. Barcellos DC, Pucci CR, Torres CRG, Goto EH, Inocencio AC. Effects of resinous monomers used in restorative dental modeling on the cohesive strength of composite resin. J Adhes Dent. 2008;10:351–4. 7. Barcellos DC, Torres CRG, Pucci CR, Borges AB, Goncalves SE de P, Limeira R, et  al. Assessment of color fidelity of several composite resins compared to their Vita Classical shade registration. Gen Dent. 58:e206–9. 8. Bowen RL.  Dental filling material comprising vinyl-silane treated fused silica and a binder consisting of the reaction product of bis-­ phenol and glycidyl acrilate. 1962. p. 27. 9. Breschi L, Cammelli F, Visintini E, Mazzoni A, Vita F, Carrilho M, et al. Influence of chlorhexidine concentration on the durability of etchand-rinse dentin bonds: a 12-month in  vitro study. J Adhes Dent. 2009;11:191–8. 10. Cadenaro M, Biasotto M, Scuor N, Breschi L, Davidson CL, Di Lenarda R.  Assessment of polymerization contraction stress of three composite resins. Dent Mater. 2008;24:681–5. https://doi.org/10.1016/J. DENTAL.2007.06.031. 11. Cox CF.  Microleakage related to restorative procedures. Proc Finn Dent Soc. 1992;88(Suppl 1):83–93. 12. Dietschi D. Free-hand bonding in the esthetic treatment of anterior teeth: creating the illusion. J Esthet Dent. 1997;9:156–64. 13. Fahl N.  Predictable aesthetic reconstruction of fractured anterior teeth with composite resins: a case report. Pract Periodontics Aesthet Dent. 1996;8:17–31. 14. Fradeani M. Reabilitação Estética em Prótese Fixa. São Paulo: Quintessence; 2006. 15. Fraser T, Banks A.  Color: La Guia Más Completa. Barcelona: Evergreen; 2004. 16. Garberoglio R, Cozzani G.  In vivo effect of oral environment on etched enamel: a scanning electron microscopic study. J Dent Res. 1979;58:1859–65. https://doi.org/10.1177/00220345790580090301. 17. Güler AU, Güler E, Yücel AC, Ertaş E. Effects of polishing procedures on color stability of composite resins. J Appl Oral Sci. 2009;17:108– 12. https://doi.org/10.1590/S1678-­77572009000200007. 18. Hansen EK, Asmussen E. Effect of postponed polishing on marginal adaptation of resin used with dentin-bonding agent. Scand J Dent Res. 1988;96:260–4. 19. Ho C. Composite artistry using Premise-The new breed of nanofiller. Dent Pract. 2004;5:138–42. 20. Irie M, Suzuki K.  Effects of delayed polishing on gap formation of cervical restorations. Oper Dent. 27:59–65. 21. Joiner A.  Tooth colour: a review of the literature. J Dent. 2004;32(Suppl 1):3–12. https://doi.org/10.1016/j.jdent.2003.10.013. 22. Koenigswald W, Sander P. Tooth enamel microstructure. Rotterdam: Swets; 1997.

23. Lee Y, Lu H, Powers J.  Changes in opalescence and fluorescence properties of resin composites after accelerated aging. Dent Mater. 2006;22:653–60. https://doi.org/10.1016/j.dental.2005.08.004. 24. Li Q, Jepsen S, Albers H-K, Eberhard J.  Flowable materials as an intermediate layer could improve the marginal and internal adaptation of composite restorations in Class-V-cavities. Dent Mater. 2006;22:250–7. https://doi.org/10.1016/J.DENTAL.2005.04.011. 25. Magne P, Belser U. Restaurações Adesivas de Porcelana na Dentição Anterior. São Paulo: Quintessence; 2003. 26. McDonald R.  Colour physics for industry. Huddersfield: Charlesworth; 1987. 27. Mopper KW, O’Malley M.  The illustrated technique guide for renamel restorative system. Chicago: Cosmedent; 1994. 28. Moraes RR, Gonçalves LS, Lancellotti AC, Consani S, Correr-­Sobrinho L, Sinhoreti MA.  Nanohybrid resin composites: nanofiller loaded materials or traditional microhybrid resins? Oper Dent. 2009;34:551– 7. https://doi.org/10.2341/08-043-L. 29. Nagem Filho H, Nagem HD, Francisconi PAS, Franco EB, Mondelli RFL, Coutinho KQ. Volumetric polymerization shrinkage of contemporary composite resins. J Appl Oral Sci. 2007;15:448–52. https:// doi.org/10.1590/S1678-77572007000500014. 30. Osorio R, Pisani-Proenca J, Erhardt MCG, Osorio E, Aguilera FS, Tay FR, et  al. Resistance of ten contemporary adhesives to resin–dentine bond degradation. J Dent. 2008;36:163–9. https://doi. org/10.1016/J.JDENT.2007.12.002. 31. Roberson TM, Heymann H, Swift EJ. Sturdevant’s art and science of operative dentistry. St. Louis: Mosby/Elsevier; 2006. 32. Roulet JF, Degrange M. Adhesion-the silent revolution in dentistry. Chicago: Quintessence; 2000. 33. Rüttermann S, Krüger S, Raab WH-M, Janda R.  Polymerization shrinkage and hygroscopic expansion of contemporary posterior resin-based filling materials—a comparative study. J Dent. 2007;35:806–13. https://doi.org/10.1016/J.JDENT.2007.07.014. 34. Satou N, Khan AM, Matsumae I, Satou J, Shintani H.  In vitro color change of composite-based resins. Dent Mater. 1989;5:384–7. 35. Schwarts RS, Summit JB, Robbins JW.  Fundamentals of operative dentistry. A contemporary approach. Chicago: Quintessence; 1996. 36. Shafer WG, Hine MK, Levy BM. Tratado de Patologia Bucal. 4th ed. Rio de Janeiro: Guanabara Koogan; 1987. 37. Sterrett JD, Oliver T, Robinson F, Fortson W, Knaak B, Russell CM. Width/length ratios of normal clinical crowns of the maxillary anterior dentition in man. J Clin Periodontol. 1999;26:153–7. https:// doi.org/10.1034/j.1600-051X.1999.260304.x. 38. Terry DA. Utilization of a small-particle composite resin for anterior and posterior restorations. Pract Periodontics Aesthet Dent. 2000;12:371–8; quiz 381. 39. Torres CR, Batista GR, Cesar PD, Barcellos DC, Pucci CR, Borges AB.  Efeito da elevação da temperatura pré-polimerização sobre a microdureza superficial da resina composta. Rev da Pós Grad da USP. 2008;15 40. Torres CR, Borges AB, Kubo CH, Gonçalves SE, Araújo RM, Celaschi S. Clareamento dental com fontes híbridas LED/LASER. Santos, editor. São Paulo; 2007. 41. Torres CR, Barcellos DC, Pucci CR, de MG LG, Rodrigues CM, Siviero M. Influence of methods of application of self-etching adhesive systems on adhesive bond strength to enamel. J Adhes Dent. 2009;11:279–86. 42. Turssi CP, Ferracane JL, Ferracane LL. Wear and fatigue behavior of nano-structured dental resin composites. J Biomed Mater Res B Appl Biomater. 2006;78B:196–203. https://doi.org/10.1002/ jbm.b.30475. 43. Vanini L.  Light and color in anterior composite restorations. Pract Periodontics Aesthet Dent. 1996;8:673–82; quiz 684. 44. Yap AU, Sau CW, Lye KW. Effects of finishing/polishing time on surface characteristics of tooth-coloured restoratives. J Oral Rehabil. 1998;25:456–61. https://doi.org/10.1046/j.1365-2842.1998.00253.x.

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45. Yazici AR, Tuncer D, Antonson S, Onen A, Kilinc E. Effects of delayed finishing/polishing on surface roughness, hardness and gloss of tooth-coloured restorative materials. Eur J Dent. 2010;4:50–6. 46. Yesil ZD, Alapati S, Johnston W, Seghi RR.  Evaluation of the wear  ­resistance of new nanocomposite resin restorative materials. J  Prosthet Dent. 2008;99:435–43. https://doi.org/10.1016/ S0022-­3913(08)60105-5.

47. Zhang S, Kern M. The role of host-derived dentinal matrix metalloproteinases in reducing dentin bonding of resin adhesives. Int J Oral Sci. 2009;1:163–76. https://doi.org/10.4248/IJOS.09044.

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Composite Restoration on Posterior Teeth Carlos Rocha Gomes Torres, Marcelo Balsamo, and Satoshi Imazato 15.1

Introduction – 578

15.2

Bioactive Restorative Materials – 581

15.3

Tooth Preparation – 583

15.4

Restorative Techniques – 585

15.4.1 15.4.2 15.4.3 15.4.4 15.4.5

 cclusal Preparations (Class I or Site 1) – 586 O Restoration of Proximal Lesions Through Occlusal Access (Class II or Site 2) – 599 Restoration of Proximal Lesions through Buccal/Lingual Access – 621 Esthetic Improvement of Amalgam Restorations – 621 Repair of Ceramic or Composite Restorations – 622

15.5

Finishing and Polishing – 626

15.6

Surface Sealing – 628

15.7

Maintenance of Posterior Composite Restorations – 628 References – 629

© Springer Nature Switzerland AG 2020 C. R. G. Torres (ed.), Modern Operative Dentistry, Textbooks in Contemporary Dentistry, https://doi.org/10.1007/978-3-030-31772-0_15

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Learning Objectives The learning objectives of this chapter are related to the following topics: 55 To describe the indications and contraindication of direct composites on posterior teeth 55 To explain how the characteristic of the composite materials can influence the restorative procedure as well the clinical behavior of the restorations 55 To teach how to perform the tooth preparation with maximum preservation of the remaining tooth structure 55 To explain how to perform the restorations of cavities involving the occlusal and/or proximal surfaces 55 The importance of the proximal contact between neighbor teeth and how to properly restore it, using different techniques 55 How to apply the regular and the bulk-fill composites 55 How to improve the esthetic or to repair old restorations 55 To describe the finishing and polishing techniques for composites in posterior region 55 How to perform the maintenance of posterior composite restorations to increase its durability

15.1 

15

Introduction

The growing demand for esthetic dental procedures on the past decades increased the use of composites for the restoration of posterior teeth. Every time the patients are asked by the clinicians about which restorative material they prefer, one of metallic shade or one with the same appearance of natural teeth, almost everyone choose the esthetic restorations, even after being informed about the limitation of those materials. Although they produce good esthetics results, the composite restorations on posterior teeth present some disadvantages in relation to the amalgam ones. However, when properly indicated and performed, they may present very good clinical behavior. The composites are nowadays the most used direct restorative material on posterior teeth [40]. They are necessarily indicated on cases where the esthetics requirements are important, such as on situations where the restoration will be visible in the normal interpersonal distance, during the conversation and social life. An important advantage of composite restorations in relation to amalgam is the bonding to the tooth structure. That turns unnecessary to give any specific geometric form to the tooth preparation. When performing amalgam restoration, the restorative material and remaining tooth structure behave as two independent structures in intimate contact, with a mechanical interaction through the interface. On the other hand, when an adhesive restoration is done, the loads applied over the restoration generate internal stress, which is transmitted through the interface to the remaining tooth structure, causing both to behave as almost as a single body. That does the restoration to reinforce the remaining tooth structure [33]. The preparation is restricted to the removal of

carious tissue, with maximum preservation of the healthy remaining tooth structure [33]. Another advantage of the composite restorations is the fact that they can be easily repaired, adding a new material on the old one [33]. In addition, it is also thermal insulator due to the low thermal conductivity [33]. The light-curing composite seems to be easy to apply into the tooth preparations, using a single paste which does not cure spontaneously. However, the proper use of this material is a little complex. Even though the tooth preparation for composite restoration is simpler than for amalgam, the restorative technique is much more critical and prone to failure [33]. To produce adequate composite restorations, the clinician must have a good understanding about the bonding process, the shrinkage stress generated during polymerization, and the details and peculiarity about the light-curing procedure [15]. When compared to the amalgam restorative technique, the composite restoration takes 2.5 as much time to be done, due to a more complex restorative procedure, turning it more expensive [35]. More steps also increase the chances of mistakes. A great difficulty occurs during the restoration on proximal preparations, being more difficult the correct restoration of contour and the interproximal contact. Differently from amalgam, regular composites will not push the matrix toward the adjacent tooth during the application of the increments [33]. In addition, composites undergo a volumetric shrinkage during polymerization, which may lead to several problems on the restoration (. Fig. 15.1). Among them, gap formation on the margins allows microleakage of pigments and bacteria, leading to marginal staining and recurrent carious lesion (. Fig. 15.2a, b). In the internal walls, some debonding areas at the interface may also happen, creating internal gaps. The shrinkage stress may also generate enamel microcracks, distributed approximately parallel to the cavity margin, besides cuspal deflection. The latter may lead to enamel microcracks on buccal or lingual surfaces or even cuspal fracture, besides postoperative sensitivity (. Fig. 15.1) [33].  

 

 

>> Composites undergo a volumetric shrinkage during polymerization, which may lead to several problems on the restoration, such as gap formation on the margins, microleakage of pigments and bacteria leading to marginal staining and recurrent carious lesion, enamel microcracks, cuspal deflection, cuspal fracture, and postoperative sensitivity. The effects of volumetric shrinkage must be controlled using an appropriate restorative technique.

In the course of time, a degradation of the hybrid layer occurs, reducing the bond strength and increasing the marginal microleakage. This is caused by the hydrolysis of the dentin collagen fibers, exposed by the acid etching or acidic monomers, besides the degradation of polymers created by hydrophilic monomers in the adhesive system formulations [47]. The hydrolysis of the dentin collagen is promoted by

579 Composite Restoration on Posterior Teeth

Gap

Recurrent caries Enamel microcracks

Microleakage

Marginal staining

Marginal enamel microcracks

Internal gaps

Post-operative sensitivity

..      Fig. 15.1  Clinical problems created by the shrinkage stress during composite polymerization. (Image kindly supplied from 3 M Espe company)

..      Fig. 15.2  a SEM image of marginal gap on composite restorations created by shrinkage stress (red arrow – gap); b higher magnification of the image shown in a

a

b

Composite

Composite

Enamel

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dentin matrix metalloproteinases (MMP), which are collagenolytic enzymes released during the bonding procedure [41]. This bonding interface degradation is enhanced by the mechanical stress produced by masticatory loads, and by the stress generated due to the difference between the coefficient of linear thermal expansion (CLTE) of the composite and tooth structure, when exposed to hot or cold food and beverages, resulting in the propagation of the interfacial defects. The composite restorations also have higher wear than amalgam, mainly on the direct contact areas. The larger the restoration, the bigger is the concern in relation to the wear. The composite restorations are also more susceptible to occurrence postoperative sensitivity, especially when the adhesive technique was not properly performed. It must be considered that, the more posterior is the tooth to be restored, the harder is the isolation of the operating field and smaller is the esthetic demands of the restoration. Both factors reduce the indications for composite restorations on the second and third upper molars, where the esthetic is not critical unless the preparation extends to the buccal surface [33]. When the restoration is not visible during the conversation, some patients accept metallic materials, considering its longer durability. However, many patients desire their teeth with a natural aspect, even on areas where they cannot normally be seen [33]. Skinner stated that “the esthetic quality of a restoration may be as important to the mental health of the patient, as the biological and technical qualities of the restoration are to his physical and dental health” [39]. However, the esthetic demands are determined by the individual perception and subjected to great variation. What may please one patient may be completely unacceptable to another. Some people may be happy and proud of having gold restorations on their anterior teeth, while others think those restorations are esthetic unacceptable. It is a dentist’s duty to inform the patients about all restorative alternatives, but it must be given to them the opportunity to take the final decision in relation to which alternative will be chosen [33]. The composite restorations on posterior teeth are only indicated in Class I and II preparations (Sites 1 and 2) that can be properly isolated, since the adhesive technique is not compatible with any kind of contamination, such as saliva or blood. They are contraindicated on cases where it is impossible to obtain correct isolation of the operating field using rubber dam or cotton rolls [34, 48]. This situation is more critical on the mandibular molars or on preparations where the cavosurface angle of the gingival wall is located inside the gingival sulcus [4]. On cases where the moisture control is extremely hard or not possible, associated with the absence of enamel available for bonding on the gingival margin of the preparation, an amalgam restoration should be performed [33]. On teeth with weakened or cracked cusps, the use of an adhesive restorative material is recommended, because it can bond to and reinforce the remaining tooth structure [33]. The composite restorations are also indicated to patients allergic to certain metals. However, in large tooth preparations, the first choice would be an indirect adhesive restoration.

>> The composite restorations are only indicated in preparations that can be properly isolated, since the adhesive technique is not compatible with any saliva or blood contamination.

Ideally, occlusal contacts of the restored tooth in maximum intercuspation should occur on the remaining tooth structure, because the composite wear resistance is smaller than of enamel. When all the contacts are left over composite, it wears out and allows a dental extrusion, leading to occlusal disharmony [4]. The wear resistance refers to the material ability to resist to the surface loss, due to attrition with the opposite intact tooth or restoration (two-body wear) or abrasion with the food bolus or toothbrush (three-body wear). Clinical studies showed that the attrition wear of composite restorations, on contact areas with the opposite tooth, may be 3–5 times higher  than the abrasive wear on areas without direct contact. For this reason, direct composite restorations should preferably be performed on teeth which remaining tooth structure has direct contact with the opposite tooth. . Figure 15.3a, b shows a composite restoration with extensive abrasive wear. The material was lost by the contact with the food bolus, exposing the preparation walls.  

>> Clinical studies showed that the wear of composite restorations, on contact areas with the opposite tooth, may be 3–5 times higher than on areas without direct contact. For this reason, direct composite restorations should preferably be performed on teeth which remaining tooth structure has direct contact with the antagonist tooth.

The fillers’ size, shape, and content in a composite affect the restoration wear, as well as the location of the restored tooth, dental arch, and occlusal contacts. The wear resistance of the current composites is generally adequate for clinical use [11, 27]. Clinical studies have shown that the composite restoration wear is smaller on premolars and increases the more distally the restored tooth it is located. Of all teeth, the first molars are in contact with food bolus more often and receive the larger loads. Therefore, abrasive wear happens faster on occlusal composite restorations of those teeth. The sequence of wear severity can be described as first molar > second molars > second premolars > first premolars. Thus, small composite restorations on the first premolars present little wear risk, while large restorations on the first molars have larger risk [4]. The tooth preparation size must be considered when the restorative technique is selected. The direct composite restorations should be preferably done on small to medium size cavities [33]. On extensive ones, when the buccolingual dimensions are larger than half the distance between the cusp tips (intercuspal distance), in cases of extremely weakened teeth under heavy occlusal loads, or when one or more cusps were lost, the ideal indication is an indirect ceramic or composite restoration [33].

581 Composite Restoration on Posterior Teeth

..      Fig. 15.3  a Macrofilled chemically activated composite restoration with extensive abrasive wear. The tooth was extracted due to periodontal problems after a long time of clinical use; b the composite wear exposed the preparation walls (arrow). A rough surface can be observed due to protruding filler particles and craters and by the presence of air bubbles incorporated during the mixing process

a

b

Enamel

Composite

indicated. Due to its great hardness, the porcelain will promote unacceptable wear of the composite. In this situation, a The direct composite restorations should be performed direct amalgam or an indirect ceramic or metal cast restoraon small to medium size cavities. In case of large tion should be chosen [33]. preparations in weakened teeth, with cusp lost, indict It is also relevant to have enamel on the entire cavosurrestorations are the best alternative. face angle, which provides a significantly more effective bonding and marginal sealing than when the margins are on cement or dentin. In general, when the gingival wall of the Even though the large direct composite restorations on pospreparation extends to the root surface, without enamel on terior teeth may have many disadvantages, they can be used the gingival cavosurface angle, a gap is formed between the as an esthetic treatment alternative. Many patients cannot tooth and the composite. This happens because the composafford the costs of an indirect restoration or have medical ite shrinkage stress is greater than its initial bond strength to conditions that do not allow a more complex dental treatthe dentin [33]. In this case an amalgam or an indirect restoment. On those cases, large direct composite restorations ration should be better indicated [4]. The composite may may be used as a reasonable option, when the more long-­ also be used to repair defective restorations, either amalgam, lasting treatments are not possible [33]. The patient must be composite, or ceramic. They are also used on posterior teeth aware about the limitations in relation to the material’s propon Class VI preparations, created by the wear on the cusp erties, attending periodic dental visits to reevaluate the restotips [33]. ration [33]. The ability to reinforce the weakened remaining tooth structure turns this procedure a good option to a nonadhesive amalgam restoration [33]. The direct composite restoration in large cavities may also be indicated as a tempo- 15.2  Bioactive Restorative Materials rary procedure while waiting to determine the pulp response, when a conservative pulpal treatment was performed [33]. The traditional dental materials are designed to be biocomThe direct composite can also be used as a base for indirect patible, having a passive and neutral existence in the mouth, restorations. It can fill undermined areas and undercuts to not reacting with the oral environment. It is expected that produce the required geometry to the walls, allowing a free the material will work properly by being well accepted and causing no harm and injury. They are considered biomipath for insertion of the indirect restoration. In patients with heavy occlusal loads, due to bruxism or metic, restoring the tooth function and showing a natural clenching, the direct composite wear can be excessive, result- appearance [2]. However, it loss the opportunity of positive ing on a premature loss of the anatomical shape of the resto- gains, which a material with a more dynamic behavior ration, besides showing a higher risk of bulk or marginal could exhibit, reacting to the changes in the environment fracture. On those cases, a direct amalgam or indirect esthetic [20, 28]. The materials with such “smart” behavior are genor metallic restoration should be chosen [33, 48]. The antago- erally called bioactive. There is not a consensus about the nist tooth may also affect the wear, because a composite res- meaning of the word “bioactivity” in dentistry. However, it toration in contact with the natural opposite tooth shows can be described as the capacity of the material to give to more wear than in contact with another composite restora- the teeth something they need to keep its health and function [4]. In situations where the antagonist tooth has a feld- tion, by some kind of biologic effect. That can be related to spar porcelain restoration, a direct composite should not be an antimicrobial capacity, to reduce the biofilm activity and Tips

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prevent demineralization of the surrounding tissues, or to stimulate remineralization of the area previously affected by caries disease, strengthening the tooth structure [10]. They may have the potential to seal marginal gaps to reduce microleakage, preventing secondary caries under restorations and promoting a healthier tooth-restoration interface over time. The bioactivity can also be related to healing properties for the pulp tissue, stimulating tertiary reactional or reparative dentin formation or tubular sclerosis, protecting the pulp vitality [28]. >> The bioactivity of a restorative material can be related to its antimicrobial capacity, remineralizing potential or healing properties for the pulp tissue.

15

To offer those effects, the material must be able to release ions, such as fluoride, calcium, and phosphate, or other active substances, inhibiting biofilm formation, growing hydroxyapatite, or stimulating odontoblast cells to produce mineral deposition. Those ions can be released by special bioactive glasses or semipermeable resin microcapsules filled with ionic solutions. The bioactive materials are moisture friend, allowing a continuous ions exchange with saliva and other oral fluids, releasing and recharging their ionic components in response to pH changes. Resin composites are more susceptible to bacterial colonization than other materials for direct restorations, such as amalgam and glass ionomer cement (GIC). The enhanced bacterial attachment and biofilm formation on composites lead to occurrence of secondary caries, especially at proximal area where plaque control is difficult. Therefore, many researches to provide composites with the ability to prevent biofilm accumulation and achieve “bioactive” properties have been conducted. Less plaque accumulation on amalgam and GIC restorations are related to the release of silver, copper, zinc, or fluoride ions, which reduces  adherence and growth of oral bacteria on their surfaces. Therefore, to add ion release capacity to composites, with antimicrobial properties, is a promising strategy. There are few bioactive restorative materials currently available on the global market, containing different kind of ion releasing  glasses (e.g., Activa™, Pulpdent; Predicta™ Bioactive, Parkwell; Giomer™, Shofu) or microcapsules a Surface modified layer

Glass-ionomer phase

Fluoro-boro-alumino-silicate glass

S-PRG

(BioCoat™, Premier), associated with special monomers to produce enough physical properties in association with its bioactivity. Surface pre-reacted glass-ionomer (S-PRG) filler is a fine glass particle which has three-layered structure (. Fig.  15.4a) [19]. It contains a multifunctional fluoroboro-­aluminosilicate glass core that undergoes an acidbase reaction during manufacturing and is protected by a surface modified layer. The stable glass-ionomer phase in the middle layer allows ion release and recharge while protecting the glass core from the damaging effects of moisture. Various restorative/coating materials containing S-PRG fillers have been developed and commercialized by Shofu INC., Japan, and named as “Giomer” products. S-PRG filler releases multiple ions, i.e., fluoride (F−), borate (BO33−), aluminum (Al3+), sodium (Na+), silicate (SiO32−), and strontium (Sr2+), from its pre-­reacted glass-ionomer phase (. Fig. 15.4b). By the release of Sr2+ and Na+, S-PRG filler incorporated in resin composites can modulate the pH of surrounding environment, shifting it to neutral or weak alkaline regions. The release of F− and Sr2+ can improve acid resistance of enamel and dentin by promoting the conversion of hydroxyapatite to fluorapatite and strontiumapatite. In addition to those protective effects against demineralization, it  can reduce bacterial adherence and prevent plaque formation on their surfaces. The release of BO33− and F− significantly inhibits the growth and metabolic activities of Streptococcus mutans, leading to inhibition of oral biofilm formation [21, 30]. Additionally, ions released from S-PRG filler have the capacity to inhibit protease and gelatinase activities of Porphyromonas gingivalis and also to prevent coaggregation of periodontal diseaserelated bacteria [46]. Restoration of Class II cavities with deep preparation in the proximal box, reaching the root surface and without enamel in the cavosurface angle of the gingival wall, is always a concern in relation to secondary caries. A marginal gap will occur on almost every restoration, due to the lower bond strength and high C-factor. On those cases, “bioactive” composites with antimicrobial properties are expected to be clinically very useful, improving the prognosis and durability of the restorative treatment.  

 

b

Ions release F-

BO33-

Na+

Sr2+

Al3+

SiO32-

..      Fig. 15.4  Bioactive surface pre-reacted glass-ionomer filler (S-PRG – Shofu). a Three-layered structure; b ions released from the glass-ionomer phase

583 Composite Restoration on Posterior Teeth

15.3 

Tooth Preparation

Whenever necessary, prophylaxis with brush and pumice or airborne particle abrasion device must be performed, removing extrinsic stains and biofilm. Then shade selection and the local anesthesia are performed. It must be verified if the patient presents highly translucent enamel, indicating the use of a more translucent composite on the final layer. It is also analyzed if the adjacent teeth have any type of special characteristic, such as dark spots in the grooves or hypoplastic spots that could be reproduced [4]. The occlusal harmony also must be evaluated, verifying the teeth alignment on the arch. When an opened cavity or defective restoration remains untreated for a long time, the extrusion of the antagonist tooth and the mesialization of the caries affected or neighbor tooth may occur and must also be evaluated. The cusps of the antagonist tooth may invade the preparation to be restored during maximum intercuspation position, requiring reduction before starting the restorative procedures. The loss of the mesiodistal distance, necessary to the proper restoration of the proximal contour, may occur, due to mesialization, requiring orthodontic movement before the restoration (. Fig. 6.21). Before starting the tooth preparation, the occlusion evaluation must be performed with thin double-sided two-color articulating paper (e.g., red and black), allowing a two-tone representation of static and dynamic occlusion. The first step is to inspect the eccentric contacts (dynamic occlusion). The paper is placed on the Miller Articulating Paper Forceps, in a way that the red side is facing the tooth to be restored. The patient is asked to occlude at centric occlusion and perform protrusive and lateral excursive movements. The patient must open the mouth, and the presence of interferences during disocclusion movements must be analyzed. After that, the paper is then turned in the forceps in a way that the black side faces the tooth to be restored. The centric contact (static occlusion) is analyzed, asking the patient to close the mouth in centric occlusion and open it again. The color sequence can, of course, be altered. Whenever possible, the tooth-to-­ tooth contacts occurring during centric occlusion should not be included in the preparation outline, remaining over the intact tooth structure. In case it is not possible, care must be taken so that it will not be located over the tooth-restoration interface. Not only should the contacts on the tooth to be restored be evaluated but also on the adjacent teeth. That can help the dentist to know when the contacts on the ­restorations were correctly adjusted [33]. The anatomy and the cusp angle of the intact adjacent or contralateral teeth must be evaluated and memorized, so that similar anatomy can be reproduced on the restoration, providing the better function and esthetic. If the proximal surfaces need to be restored, preoperative wedging can be performed in the interproximal space, on such a way to increase the tooth separation, helping the reconstruction of the proximal contacts [33]. For that, a wedge is placed in the interproximal space corresponding to each proximal surface  

to be restored. If only one proximal surface is prepared, the wedge is placed only on that side. If both proximal surface will be prepared, the wedges must be placed on the mesial and distal interproximal spaces. The wedges must be tightly readapted during the preparation, because when pressed again, the teeth move even more, promoting additional separation [33]. Another way to produce a progressive dental separation is to use a separation ring, placed on the embrasures next to the surface that will be prepared. The preparation may be performed before or after the rubber dam isolation when it is used. Basically, the tooth preparation for composite restoration on posterior teeth is restricted to the removal of carious tissue, with maximum preservation of the healthy remaining tooth structure [4]. The opening of the cavity must be the most conservative as possible. On primary caries lesions located on the occlusal surface, the opening is performed using a round diamond point until reaching intact enamel on the preparation outline, exposing the carious dentin tissue (. Fig.  15.6a, b and . 15.7e–g). However, if the initial opening is not providing the necessary access for removal of remaining carious tissue, it must be enlarged as much as necessary to every wall can be inspected, especially on the region of the DEJ. This enlargement is considered a convenience form. When it is predicted that the entire mesiodistal extension of the central groove will be prepared, the opening should start on the distal area and continued mesially, allowing a better visualization during the procedure [33]. If there are some separated small lesions, they do not need to be connected during the preparation, remaining as separate cavities. The highly infected superficial dentin must be removed, although the more internal softened dentin can be preserved, because it can be remineralized, as described in 7 Chap. 6. Other areas of the tooth surface that are not cavitated but present a high caries risk, due to biofilm deposition, may be sealed (more information about that is available on 7 Chap. 16).  

 

 

 

Tips

Basically, the tooth preparation for composite restoration on posterior teeth is restricted to the removal of carious tissue, with maximum preservation of the healthy remaining tooth structure.

The outline and depth of the preparation are defined by the lateral extension and depth of carious tissue and other defects. The main goal of this preparation is to remove the infected tissue in the most conservative way possible. The retention form is obtained mainly by the bonding to the tooth structure, instead of by the mechanical characteristics of the preparation [33]. There are two situations when a composite restoration is indicated. The first one is when there is a previous defective amalgam or composite restoration which needs to be

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replaced, and the second is when there is a primary carious lesion. When there is a defective restoration, it must be removed avoiding any additional cut of the remaining tooth structure. No modification of the preparation shape must be done. The old restorative material must be completely removed to evaluate the cavity walls. Leaving old amalgam under a new composite restoration may result on poor esthetic [33]. To avoid an additional cut of the preparation walls, the amalgam restoration can be sectioned and the fragments removed with a dental exploratory probe ­ (. Fig. 15.8f–h). The amalgam oxide residues can be removed with an airborne particle abrasion, followed by copious rinsing, avoiding the use of rotary instruments if no carious tissue is remaining (. Fig. 15.8i). The carious dentin tissue can be removed with a round bur at low speed, of the largest size compatible with the preparation dimensions. There is no need to remove the undermined enamel since the adhesive restoration will be able to reinforce the remaining tooth structure. The same way, even if the pulpal walls have different depths on each place, there is no need to make it flat. In general, the vertical surrounding walls will be convergent toward the occlusal surface, with a concave pulpal wall. The internal angles will be round, as a consequence of the round shape of the bur. Those characteristics also contribute for the adaptation of the restorative material on the region of the internal line angles of the second set. The preparation of posterior teeth for composite with a box shape, as used for the amalgam, increases the negative effects of the C-factor and is not recommended [33]. No bevel should be performed on the occlusal cavosurface angle, avoiding thin restoration margins, which would fracture under the occlusal loads [4, 33]. The bevel on the occlusal cavosurface angle also increases the restored area, which expands the composite surface subjected to wear. The beveling on the gingival cavosurface angle should never be performed too, because it  may completely remove the remaining enamel on the region, resulting on bonding to dentin or cement, which is worse than the one obtained to enamel. When the lesion is located on the proximal surface with intact marginal ridge, the entry direction must be chosen. In general, the caries lesions on the proximal surface are located just below the contact area [33]. If the lesion is small and close to the occlusal surface, or if the lesion is large, but there is a small remaining of the marginal ridge, the access must be done from the occlusal surface. For that, the adjacent tooth must be protected with a steel strip and the gingival papillae with a wooden wedge (. Fig.  15.11d) [4]. The preoperative wedging is performed before starting the preparation, helping to restore the proximal contact [33]. The preparation is started with a round diamond point entering on the top of the marginal ridge, opening a channel, mainly on enamel, trying to keep a thin layer of remaining enamel between the preparation and the adjacent tooth, avoiding to touch the bur on the proximal surface of the neighbor tooth. The entry should follow the DEJ.  When reaching the caries lesion, it will be noticed by the dentist a feeling of falling on a hollow  

 

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space. Any remaining enamel still in contact to the neighbor tooth can be fractured with a hand instrument or removed with a bur. The remaining carious tissue is removed with a round bur at low speed or dentin excavator [33]. The preparation outline must be the most conservative as possible but allowing enough access for removal of remaining the carious tissue. Because of that, generally the buccal and lingual walls will be convergent toward the occlusal surface, giving the proximal box the pear or drop shape [33]. No bevel is performed, and any undermined enamel prisms will be left and reinforced by the adhesive restoration. The buccolingual and occlusogingival dimensions must be the most conservative as possible, determined by the lesion size [33]. The internal angles will be round due to the shape of the rotary instrument used for preparation. The gingival wall will be concave and extended until the gingival end of the lesion. The contact with the adjacent tooth does not need to be removed, since this type of restoration should only be performed on patients with good oral hygiene, and the region of the tooth-restoration interface will be frequently cleaned by flossing. Even though keeping this contact can adversely affect the matrix placement, to get maximum preservation of remaining tooth structure is more relevant than any technical difficulty. Conversely, to obtain adequate proximal contact for the restoration will be easier [33]. When the visual and/or tactile evaluation of the gingival or axial walls is difficult, the axial wall can be prepared expulsive toward the occlusal surface, as a convenience form for visibility. Internal stains on the buccal or lingual walls or under the occlusal enamel, seen through the translucent remaining enamel, even when related to intact sclerotic dentin should be removed, because they can be misdiagnosed in the future as recurrent caries lesion [33]. When the caries lesion is more cervically located or displaced toward the buccal or lingual surfaces, the dentist can choose to perform the access to the lesion through the buccal or lingual embrasures, performing a horizontal slot preparation, obtaining the maximum preservation of the remaining tooth structure (. Fig.  15.15a–f) [33]. This preparation is similar to a Class III preparation on anterior teeth. The adjacent tooth must be protected with a metal strip and the access performed with a small round diamond point. The instrument must be placed on the correct occlusogingival position, guided by the lesion position observed on the radiography. The entry is performed as close as possible to the adjacent tooth. The carious dentin tissue is removed with a round bur at low speed or with a spoon excavator [33]. The access must be the most conservative as possible, enough to allow the removal of carious tissue. This way, the occlusal and gingival walls generally will converge toward the entry surface. On the other hand, when there is not an adjacent tooth, or there is a preparation on the neighbor tooth that allows direct access to the lesion, the entry direction can be strictly proximal. The final shape of the preparation will be the one that results after the removal of the entire carious tissue. In general, this type of preparation is only possible on the mesial tooth surface because of visibility [4].  

585 Composite Restoration on Posterior Teeth

Tips

When the caries lesion is located on the proximal surface, with intact marginal ridge, the best entry direction for the preparation must be chosen, in order to obtain the maximum preservation of the tooth structure. If the lesion is small and close to the occlusal surface, or if it is large, but there is a small marginal ridge remaining, the access must be done through the occlusal surface. However, when the lesion is more cervically located or displaced toward the buccal or lingual surfaces, the access through those areas is recommended.

15.4 

Restorative Techniques

For restorations of posterior teeth, the light-activated nano−/ micro-hybrid or nanofilled composites should be selected, because they present the required physical properties to undergo the stress generated by the occlusal loads. The microfilled composite, even though having a good wear resistance, when used on posterior teeth may fracture due to its low filler content. The macrofilled composites showed high levels of wear, creating a very rough surface due to the exposure of the large filler particles after loss of the organic matrix. Some filler particles are plucked from the surface, resulting in craters. The chemically activated composites should also be avoided, because the mixing procedure can incorporate air bubbles into the material, which would increase the surface roughness (. Fig. 15.3a, b). If the prophylaxis has not been performed before the tooth preparation, it must be done before starting the restorative procedure. Then, the isolation of the operating field is performed, and the need for additional pulpal protection is analyzed (see 7 Chap. 9). Whenever necessary, the application of the most adequate protective material is performed. On shallow or medium depth preparation, it is not necessary any type of lining material. On deep preparation, a layer of GIC can be applied only on the pulpal or axial wall (. Fig. 9.17a–d). However, if it is noticed the presence of dark and hard sclerotic dentin on the internal walls, no additional protection is required. When a pink discoloration is observed on the internal walls, in the region corresponding to the pulp horn, the preparation is considered very deep. That indicates that less than 0.5 mm of dentin is remaining and there might exist some clinically undetected pulp microexposures. A thin layer of calcium hydroxide cement is applied only over that area, which is covered by a thin coat of a GIC, sealing the region and preventing that the acid used on the adhesive procedures dissolves the calcium hydroxide liner (. Fig. 9.18d–i) [33]. It is recommended to cover the minimum necessary of the preparation walls, because the liner reduces the area of dentin available for bonding [33]. In case of accidental pulpal exposure, the direct pulp capping procedure can be performed (. Fig. 9.20). A Class I preparation has a C-factor equals five, with five bonded and one unbonded walls (see 7 Chap. 13). Therefore,  

 

 

 

 

 

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if a composite is applied in a bulk increment, there is a large risk of bonding interface rupture during the polymerization, due to the material shrinkage, especially along the pulpal wall and on the marginal region. The shrinkage stress can be reduced using a gradual curing protocol of soft start, in ramp or step, as described in 7 Chap. 13, prolonging the pre-gel phase during polymerization. For that, special light-curing devices that automatically adjust the emittance (power emitted) can be used. However, it is also possible to control the irradiance (power incident) using conventional devices, by changing the distance between the light guide tip and the composite surface. In addition, the incremental or layering technique proposed by Lutz et  al. [25] can be used, where each increment is applied over fewer walls as possible, generally two at a time, always leaving the larger amount of unbonded surfaces, creating conditions to reduce the stress at the interface. Oblique increments should be applied, touching the buccal and pulpal or lingual and pulpal walls, avoiding connecting the buccal, pulpal, and lingual walls at the same time. Techniques for stress reduction are extremely relevant, especially on cases of weakened cusps, that may suffer deflection of 15 μm on the first 15 min after the end of the restoration and up to 18–30 μm after a week [7, 29]. After the light-curing, the “dark-curing” of the composites continues at a significant rate for about 20  min after the light-curing and a slower rate for at least 24 h [4]. Some studies recommend the application of a thin layer of flowable composite on the internal walls of the preparation, as a low-elastic modulus liner, which works as a stress-­ absorbing layer, before the application of a more viscous material. This layer would reduce the stress on the tooth-­ restoration interface, preserving its integrity [4]. The flowable composite also fills more easily the undercuts and irregularities on the walls and internal angles of the preparation [4]. This is even more relevant when replacing amalgam restorations, which preparations have more acute angles. The more viscous is the restorative composite to be applied, the higher are the chances of a bad adaptation of the composite to the preparation walls, and more advantageous is to use the flowable composite liner [4]. The GIC can also be used as a base under composite restorations as a stress-absorbing layer [33]. Many studies have shown that GIC application, under composite restorations, reduces the total amount of shrinkage stress that the remaining tooth structure undergoes during composite polymerization. In general, the more GIC it is applied, the less stress is generated [18, 42]. An in vitro study showed that the use of a GIC base significantly reduced the cuspal deflection in the MOD preparation restored with composite [1]. Another study has shown that the use of a GIC base applied before the composite improves the marginal adaptation and reduces the microleakage [37]. This technique is called “selective bonding,” because the adhesive system will bond only to the walls’ areas not covered by the base material. On the “total bonding” technique, the adhesive system is applied over the whole preparation walls [37]. Besides the low-elastic modulus of the GIC applied, which works as a stress-absorbing layer, the favorable  

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results of the selective bonding technique are certainly due to the fact that the total volume of composite applied for the restoration is reduced, when the base material is applied. The conventional GIC, which is the most indicated for this technique, may be associated with the previous etching of the dentin surface, to remove the smear layer, improving its bonding to the tooth structure. A weak acid is used, such as the 10–25% polyacrylic acid, applied on the tooth surface for 15–30 s, followed by washing and drying with a gentle airstream. After the initial set of the conventional GIC, its surface can be etched with a phosphoric acid gel for 5 s, before applying the adhesive system, improving its bonding to the composite applied above [31]. The resin modified GIC (RMGIC) may also be used. It should be avoided the use of sticky composites, because this characteristic adversely affects its application into the preparation, leading to voids on the tooth-restoration interface or between the increments, creating weak areas where failures can propagate, such as gaps or cracks [4]. They are also difficult to be shaped for restoring the proper tooth anatomy [4]. In addition, materials with excessively high viscosity shows bad wetting properties to the preparation walls, being difficult to adapt, leaving spaces and air bubbles at the interface [4]. One of the most important steps for proximal restorations of the posterior teeth is the correct choice and placement of the matrix band. Different from amalgam that can be condensed, helping to create the proximal contact, the composite restoration is almost completely dependent on the contour and position of the matrix band to create the proper proximal contacts [33]. Before applying the composite, the matrix strip must be firmly touching the contact area of the adjacent tooth [33].

mirror that improves the polymerization, reflecting the light transmitted through the composite back to the material [4]. The thinner strips, with about 0.03  mm (0.0015 inches), should be chosen, instead of the thicker ones with 0.05 mm (0.002 inches) commonly used for amalgam restorations, so less dental separation will be required. The metallic strips may be easily contoured and suffer less distortion under forces created during the material adaptation into the preparation, which is an important property when a more viscous composite is used, reducing the overflow through the cavosurface angle [4]. Clinical studies showed that the use of clear plastic matrix associated with reflective wedge does not improve the clinical behavior of composite restoration in relation to the use of the metallic bands and wooden wedges [9, 12]. On cases where both mesial and distal surfaces were prepared, after placement of the matrix band, it is recommended to use of the wedge alternation technique. A single wedge is inserted, starting in one of the interproximal spaces, followed by restoration of this corresponding proximal surface and the contact. Then, the wedge is removed and inserted into the other interproximal space, and the second proximal surface is restored. This procedure can allow the maximum dental separation by the wedge at the moment to restore each proximal box (. Fig. 15.10i, p).  

Tips

On cases where both mesial and distal surfaces were prepared, after placement of matrix band, it is recommended to use the wedge alternation technique, restoring one proximal surface at a time.

Tips

15

One of the most important steps for proximal restorations of the posterior teeth is the correct choice and placement of the matrix band. The composite restoration is almost completely dependent on the contour and position of the matrix band to create the proper proximal contacts. The matrix strip must be firmly touching the contact area of the adjacent tooth.

15.4.1 

On teeth with more translucent enamel, to obtain the better shade and translucency match, the enamel and dentin shade composite layers can be applied, similarly to the original structure, using a stratified layering technique. On . Fig. 15.5a–f are shown the external morphological aspects of the tooth structure of some posterior teeth, as well the internal morphology of the dentin tissue, after the dissolution of the enamel by the immersion in an acidic solution for some days. It can be observed that the dentin follows the external tooth morphology. This can be reproduced during the restorative procedure. To obtain an esthetic reconstruction of the lost tooth structure, simulating the natural morphology, composites with different translucency levels are used, restoring first the lost dentin (opaque) and then the enamel (more translucent) (. Fig.  15.6a–g´). The material must be applied in oblique increments, leaving unbonded walls, avoiding connecting more than two walls at the same time, in an attempt to reduce the negative effects of the high C-factor. Each layer must have a maximum thickness of 2 mm, to provide a good curing on  

In the past, clear plastic bands associated with reflective wedges were recommended to restore posterior teeth with composite, because it was considered that the composite shrinkage occurs toward the light source, and this procedure would improve the marginal adaptation of the restoration [26]. However, several studies proved that this does not happen and that the shrinkage occurs toward the bonded walls, despite the position of the light source [4, 44]. In addition, the plastic matrices are hard to contour and also hard to pass through the proximal contact, on the intact surface of the tooth to be restored. They are generally thicker than the metallic bands and require more dental separation [4, 33]. Therefore, the metallic bands are nowadays the most indicated for composite restorations on posterior teeth using occlusal access. Besides being easier to use, they work as a

Occlusal Preparations (Class I or Site 1)

 

587 Composite Restoration on Posterior Teeth

a

b

c

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..      Fig. 15.5  External and internal morphological aspects of posterior teeth. a, c, e Intact teeth; b, d, f dentin view after the dissolution of the enamel by the immersion in an acidic solution for some days

the bottom area. If there are regions of undermined enamel, they must be filled first and correctly light-cured. The initial polymerization of the composite on those areas can be done through the tooth structure, reducing the amount of light reaching the composite at the beginning of the curing process, reducing the shrinkage stress. The curing is then complemented from the occlusal surface (. Fig. 15.6i–o). To simplify the placement of the increments, small amounts of the composite can be shaped by hand as small spheres, using dust-free gloves, and applied into the preparation using a nonstick composite filling instrument, creating a  

conical shape layer. The composite should be placed using rapid shallow strokes, reducing the chance of detaching it from the cavity wall, which can create voids. This first increment, using an opaque dentin shade composite, is applied touching the pulpal wall and the lingual or buccal wall (. Fig. 15.6p, q). Each increment is light-cured for at least 20 s. The next increments touch the opposite external wall and the pulpal wall at the same time, as well as the previous increment that has already been polymerized. It should be avoided that increments of dentin shade composite reach the cavosurface angle, leaving space for the external layer of enamel shade  

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material (. Fig.  15.6r, s) [4]. If the dentist decides to create effects of white spots, such as hypomineralized areas of enamel, small portions of white opaque tint can be applied over the dentin shade composite already cured. The last layers are placed using translucent enamel shades, shaping the occlusal surface, preferably restoring each cusp at a time (. Fig. 15.6t–w). For  

 

shaping the occlusal surface, nonstick instruments with a probe- or conical-shaped nib can be used (. Fig.  15.6u, v). After inserting the material into the cavity, the instrument nib must be placed on the region of the ­central groove to be created, while the side rests over the remaining tooth structure of the occlusal surface, touching the cavosurface angle. Then the  

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..      Fig. 15.6  Restoration of Class I preparation. a Opening of the cavitated caries lesion; b removal of the carious dentin tissue; c, d acid etching; e blot drying; f visibly moist dentin surface; g application of the adhesive system; h light-curing of the adhesive; i view of the undermined buccal cusps; j, k filling the undermined areas; l lightcuring through the tooth structure; m, o filling the undermined enamel on the lingual cusps and light-curing; p placement of oblique increments using dentin shade composite (Grandio SO – Voco);

q, r placement of dentin shade composite increments; s space left for the application of enamel shade composite; t–w application of enamel shade composite using nonstick instruments of conical- and probeshaped nibs; x application of brown tint to simulate darkened grooves; y tint applied into the grooves; z clear oxygen-blocking gel; a´ gel application and light-curing through it; b´ finishing with fine grit diamond points; c´, d´ polishing with silicon carbide brushes; e´, f´ surface sealing; g´ final restoration

589 Composite Restoration on Posterior Teeth

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..      Fig. 15.6 (continued)

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..      Fig. 15.6 (continued)

591 Composite Restoration on Posterior Teeth

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d’

..      Fig. 15.6 (continued)

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e’

f’

g’

..      Fig. 15.6 (continued)

15

instrument is moved mesiodistally, copying the inclination and all the existing details of the remaining cusp inclines and groves, which guide the shaping procedure. The use of increments on the stratified layering technique reduces the shrinkage stress at the interface and the cuspal deflection. It also reduces the incorporation of air bubbles on the interface and improves the adaptation of the material on the walls, decreasing the marginal microleakage. In addition, it reduces the amount of excess of restorative material at the margins and the use of rotary instruments to remove them later on. It allows obtaining of a polychromatic restoration and a more complete light-curing of each increment [4]. On the cases of neighbor teeth with darkened grooves, tints can be used to reproduce this characteristic on the restoration. However, it is always recommended to ask the patients if they accept this characterization [4]. For that, very thin and deep grooves can be shaped on the external layer of enamel shade composite, using a sharp exploratory probe, followed by light-curing. Then, a small amount of brown or ochre tint is applied into the groove with a probe. The excess over the surface is removed using a disposable applicator, and the tint is light-cured (. Fig. 15.6x, y and 15.7t, u). Only the tint on the deepest areas of the grooves should remain. Another option is to apply the tint in the grooves shaped with the dentin shade composite, which will be covered with a translucent enamel shade material. With the use of the layering technique,  

after curing of the last layer, the restoration should have an almost perfect shape, being required only small finishing. The external surface of the shaped composite will directly contact the food bolus and the antagonist tooth, being susceptible to wear. As the oxygen in the atmosphere has contact with the composite surface, it will prevent its complete polymerization, creating an oxygen inhibition layer, making this critical region not reaching its maximum mechanical properties. To overcome this problem, the surface can be covered with transparent glycerin-based oxygen-blocking gel. Then, the light-curing can be applied through it for 20 s, completely curing the composite surface (. Fig. 15.6z, a´). After that, the occlusion must be evaluated using an articulating paper. Any premature contact and interference during the excursive movements must be removed. The patient goes home, and the finishing and polishing can be performed on the next appointment, after the “dark-curing” of the composite has been complete. Further details are presented at the end of this chapter.  

Tips

To prevent the presence of an oxygen inhibition layer, the last composite increment can be covered with transparent glycerin-based blocking gel, followed by an additional light-curing through it, creating a fully polymerized surface.

593 Composite Restoration on Posterior Teeth

On the cases of hidden caries lesions, when the occlusal surface is intact, a direct custom-made occlusal stamp can be prepared to help the restoration of the tooth anatomy (. Fig. 15.7a–a´). First, the occlusal surface is isolated with a thin coat of petroleum jelly, and then the acrylic resin is applied. That can be done using a brush soaked with the liquid resin monomer, which is put in contact with the polymer  

powder to carry it to the tooth surface (. Fig. 15.7d). Other possibilities are to use light-curing transparent flexible temporary filling material (e.g., Fermit -Ivoclar Vivadent or Clip F -Voco) or a flowable composite (Clip flow - Voco). A small handle can be prepared for the stamp with the same material or using a disposable adhesive applicator. The stamp is removed and works as an index, replicating the original  

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..      Fig. 15.7  Direct custom-made occlusal stamp and hidden carious lesion. a–d Copy of the occlusal morphology with acrylic resin; e, g lesion opening and outline form; g removal of the carious dentin; h finished preparation; i–k etching and application of the adhesive system; l, m filling undermined cusp areas with dentin shade composite GrandioSO (Voco); n restoration of lost dentin area; o application of a separating agent on the stamp; p enamel shade composite applied;

q, r stamp fitting and removal of excess; s light-curing through the stamp; t, u application of brown tint into the grooves and excesses removal; v application of oxygen blocking gel; w final light-curing through the gel; x finishing with aluminum oxide mounted stone; y polishing with diamond-embedded abrasive rubber point Dimanto – Voco); z, a´ final result

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..      Fig. 15.7 (continued)

595 Composite Restoration on Posterior Teeth

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..      Fig. 15.7 (continued)

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..      Fig. 15.7 (continued)

anatomy of the tooth structure. After the operating field isolation, bonding procedure and placement of the dentin shade composite, the stamp receives a separating agent, such as a hydrosoluble glycerin-based gel, liquid soap, or a piece of PVC cling film, and a single increment of enamel shade composite is placed into the preparation but not light-cured. Then, the stamp is taken in the original position and pressed. The composite overflow is removed, and the initial lightcuring is performed through the stamp. Then, it is removed, and the light-curing is complemented for more 20 s. This

way the ideal original occlusal anatomy is quickly restored (. Fig. 15.7o–s). In cases of replacement of several defective restorations, to simplify the restorative procedure and save clinical time during the shaping of the occlusal surface, indirectly made occlusal stamps can be prepared. For that a plaster model of the teeth to be restored is previously obtained, through an impression with alginate (. Fig. 15.8). On the plaster model, the area corresponding to the old restorations is cut with a bur to create space for waxing. The shape of the new restora 

 

597 Composite Restoration on Posterior Teeth

tion can be created on wax by the dentist or a laboratory technician (. Fig. 15.8b, c). An occlusal stamp can be made the same way as already described, but now outside the mouth (. Fig.  15.8d, e). When a flowable composite is used (e.g., Clip flow  – Voco), the handle can be prepared by applying  

 

composite and light-curing at the same time. All the stamps are previously prepared and then available for the dentist, which can schedule the patient for a next appointment to perform the restorations, the same way that has already been described for the stamp made directly in the mouth.

a

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..      Fig. 15.8  Indirectly made occlusal stamps. a Defective r­ estoration; b, c grinding of the plaster model and waxing; d, e stamp preparation using high translucency temporary flowable material (Clip Flow – Voco); f careful sectioning of the old amalgam restoration, separating it in small pieces, avoiding to touch the bur on the walls; g, h removal of amalgam pieces with an exploratory probe; i preparation after cleaning with prophy-jet device and pressurized slurry of sodium bicarbonate,

to remove the amalgam oxides, followed by thorough rinsing with air/ water spray; j removal of the remaining carious dentin tissue; k, l acidic etching and application of the adhesive system; m placement of dentin shade composite GrandioSO Voco); n application of enamel shade composite; o Enamel shade composite applied but not light-cured; p–r application of a separating agent on the stamp, fitting and light-curing; s result without the characterization; t final result

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..      Fig. 15.8 (continued)

599 Composite Restoration on Posterior Teeth

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..      Fig. 15.8 (continued)

15.4.2 

 estoration of Proximal Lesions R Through Occlusal Access (Class II or Site 2)

On preparations involving the proximal surface in contact with a neighbor tooth, it will always be required to use matrix and wedge. The wedge has the purpose to separate the teeth to compensate the thickness of the matrix strip, stabilize the matrix band, and prevent the overhangs at the gingival margin [33]. The application of the matrix before or after the adhesive system depends on the clinical situation. Some dentists prefer to apply the matrix and wedge before, which can

help to obtain good isolation and prevent any contamination of the preparation walls. It also allows evaluating if any fractures occur on the cavosurface enamel margins, due to the matrix and wedge placement, before performing the adhesive application. However, in this case, care should be taken to avoid adhesive pooling along the preparation margins, which would create a radiolucent area on the interface between the composite and the wall, that may be misdiagnosed as secondary caries. The excess of adhesive must be removed with the airstream, dry disposable applicator, or a thin aspiration cannula before light-curing. The application of the matrix before the adhesive can be even more beneficial

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when the gingival wall of the proximal box is very deep [33]. Other dentists prefer to apply the adhesive before placing the matrix. The advantage for this is to avoid adhesive pooling along the preparation margins and maximize the application of the adhesive on the cavosurface angle. However, after matrix application, the margins must be evaluated to see any fracture of the marginal enamel has happened, which could result on the composite placement over nonbonded enamel. A frequent problem with this technique is the pooling and curing of the adhesive beyond the margins, sometimes inside the gingival sulcus, which adversely affects the adaptation of the matrix to the external tooth surface. This excess of cured adhesive must be completely removed with an exploratory probe before the matrix placement. Therefore, the matrix can be placed either before or after the adhesive, since a careful technique is performed [33]. Tips

The matrix band and wedge can be placed either before or after the adhesive application, since a careful technique is performed, avoiding pooling on the margins, which can be misdiagnosed as secondary caries.

15

The main challenge when using a composite to restore posterior teeth is to obtain proper interproximal contacts. This is related to the viscosity of this material, which is different from amalgam and cannot be condensed and pressed toward the matrix during the application into the preparation. Due to this fact, some techniques were developed to overcome this problem, which is presented next. To restore the proximal surface of posterior teeth with composite, sectional matrix placed in only one proximal surface or circumferential matrix surrounding both proximal surfaces can be used during the restoration. 15.4.2.1 Sectional Matrix with a Separation

Ring

An option to help obtaining adequate proximal contacts is the use of a pre-contoured sectional matrix associated with a separation ring (. Fig. 15.9a–u). It is especially advantageous when only one proximal surface will be restored, because the intact contact on the other proximal surface does not need to receive the band, reducing the amount of teeth separation necessary to compensate the thickness of the matrix. Some in  vitro studies, measuring of the contact tightness, have shown that separation rings and sectional matrices create tighter contacts than the circumferential matrix [23, 24, 36]. The preoperative wedging used during the preparation is  removed, the matrix band is placed, and a new wedge is  inserted [33]. The convex matrix edge is placed cervically, while the convex side must face the adjacent tooth  (. Fig.  8.8). A matrix with occlusogingival width compatible with the dimensions of the preparation must be chosen (. Fig. 15.9e). Its height must be enough to place the  

 

 

gingival edge of the band 1 mm below the cavosurface angle of the gingival wall and the occlusal edge 1 mm beyond the marginal ridge of the adjacent tooth [33]. The wedge is inserted from the larger embrasure. Then, the separation ring is placed in the embrasure regions, separating the teeth and stabilizing the band, also helping to compensate the thickness of the matrix strip. In addition, the ring brings the matrix borders in contact to the remaining tooth structure, avoiding the composite overflow at those areas. The separation ring is taken in position with a clamp forceps and must touch the proximal surface of both teeth in each embrasure at the same time. For that, it must be placed over the wedge. However, on the case of teeth with short clinical crown, the ring may not obtain adequate stability. On this case, the wedge can be shortened in a way to not adversely affect the ring adaptation. An option is to use special separation rings, such as Composi-Tight 3D (Garrison) or Palodent Plus (Dentsply), with notches on its tines, which allows the wedge to pass through it, not interfering on the ring adaptation (. Fig. 8.9a–d).  

Tips

The matrix band height must be enough to place the gingival edge of the band 1 mm below the cavosurface angle of the gingival wall and the occlusal edge 1 mm beyond the marginal ridge of the adjacent tooth. The wedge is inserted from the larger embrasure.

There are several types of separation rings. Some of them have narrow tines with round cross section, while others have larger and flat tines with a rectangular cross section (. Fig. 8.8d). On the cases of preparations where the margins of the buccal and/or lingual walls of the proximal boxes, in the embrasure region, are too far from the proximal surface of the adjacent teeth, the rings with larger flat tines are preferred, because they touch the external tooth surface beyond the preparation margins (. Fig. 8.8d 2). In this kind of situation, the ring with thin round cross-sectional tines will penetrate into the preparation, collapsing the matrix and not promoting the required tooth separation. On the cases where the buccal and lingual proximal extensions of the proximal box do not extend significantly onto the buccal and lingual surfaces, the rings with round cross-sectional tines are more adequate, because they allow a better wrapping of the matrix around the tooth (. Fig. 15.9g, h). After the ring placement, the sealing of the matrix on the margin of gingival wall is evaluated with an exploratory probe, followed by the burnishing of the strip toward the adjacent tooth using the backside of a spoon excavator  blade. If pre-contoured sectional matrices and separation rings are not available, the dentist can prepare a custom-made sectional matrix, as described in 7 Chap. 8, using a piece of the straight band, a little longer than the buccolingual dimensions of the preparation. It is first burnished over a paper mixing pad using an egg shape burnisher. Then it is placed firmly wedged, and then it is  

 

 

 

601 Composite Restoration on Posterior Teeth

s­ tabilized with low fusion compound or light-cured gingival barrier on buccal and lingual embrasures. When applying the compound, the matrix must be kept in contact with the adjacent tooth using a burnisher. If extra contouring is required at this moment, the backside of a heated dentin spoon can be used [33]. Details of this matrix technique can be seen in . Fig. 8.7a–f.  

The restoration is started using enamel shade composite, applied with the incremental technique, restoring the proximal surface. The first layer can touch the buccal and gingival walls, being light-cure, while the next touches the lingual and gingival walls, as well as the first already cured layer. The preparation is filled until it reaches the marginal ridge height of the adjacent tooth, shaping the outer incline of the

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..      Fig. 15.9  Use of sectional matrix and separation ring. a Initial aspect; b–d tooth preparation; e different sectional matrix sizes and separation rings; f placement of matrix and wedge; g use of ring with rectangular cross-sectional tines; h better adaptation on the embrasures using a ring with narrow tines and round cross section; i, j acid etching and application of the adhesive system; k placement of an oblique increment restoring the proximal surface; l proximal surface

completed; m proximal surface restored after matrix removal; n, o dentin shade composite oblique increments; p placement of the first enamel shade increment; q last increment of enamel shade composite (GrandioSO – Voco); r surface characterization of the groove; s finishing with multi-bladed bur; t polishing with diamond abrasive rubber point (Dimanto – Voco); u final aspect after hydration

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..      Fig. 15.9 (continued)

603 Composite Restoration on Posterior Teeth

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­arginal ridge with a probe-shaped nib instrument m (. Fig. 15.9k–m). After restoring the proximal surface with a thin layer of composite, the matrix can be removed, which turns easier the rest of the restorative procedure. The internal area of the preparation is restored using dentin shade composite, through oblique increments, the same way as already described for Class I preparations. Some space should remain to be filled with an enamel shade composite. After the final light-curing from the occlusal surface, the polymerization can be complemented from buccal and lingual surfaces through the remaining tooth structure [33]. The restorations must be examined from different angles to analyze the final anatomical reconstruction, the presence of hollows due to the lack of material on the margins. The quality of the proximal contact can be evaluated by passing a dental floss between the teeth. If corrections are required, new material can be applied since the surface had not been contaminated. A new layer of composite easily bonds to the oxygen-inhibited layer of the light-cured composite [33]. However, if any finishing has already been performed with a bur, and more material needs to be added, the surface must be etched with phosphoric acid, for cleaning, and an adhesive be applied before placing more material. On MOD preparations, the restoration should preferably be started in the distal box, reconstructing the distal surface in contact with the adjacent tooth. After that, the wedge and matrix should be removed and a new band and wedge placed on the mesial box. A band should not be reused because it is already deformed and may not produce a proper contour to the restoration. After reconstruction of the mesial surface, the wedge and matrix are removed, and the restoration of the occlusal surface can be performed like in a Class I preparation. Despite the restorative technique, the composite should reach its maximum polymerization; otherwise, the success of the restoration will be compromised, risking the adhesive interface and the strength of the restorative material. The composite should reach its maximum of conversion degree, which is around 60–70% [32]. Even though the stratified layering technique, using an enamel and dentin shade composites, may produce excellent results for most patients, some of them have a more opaque enamel and does not required the use of two different materials. A single shade with medium translucency can be used, simplifying the placement technique.

the intact contact, reduces the teeth separation and makes contact harder to achieve [4]. Therefore, the sectional matrices have advantages. However, when properly applied, the circumferential matrices can also be used with great success. For that, a very thin metallic band has to be chosen, as well as some type of matrix retainer. There are available at dental market different kinds of circumferential matrices, such as flat straight and flat Tofflemire strips, as well as the pre-contoured Tofflemire ones. Because the flat straight strip is not pre-contoured, after the assembling on the retainer, the area corresponding to position of the proximal surface has to be burnished over a paper mixing pad, using an egg shape burnisher, creating a convex contour on the opposite side, similar to the proximal tooth surface (. Fig. 15.10d) [33]. Then, it is taken in position and the wedged is inserted. The wedges must be firmly applied using a careful technique, because the separation provided must compensate the thickness of the band on the mesial and distal proximal surfaces [33]. When there are two proximal boxes to be restored, the wedge alternation technique should be used (. Fig. 15.11). It means that a wedge is first inserted in only one interproximal space and this proximal surface is restored. Then, the wedge is removed and inserted into the other interproximal space, and then this area is restored. This promotes a greater dental separation than if both wedges were inserted simultaneously [22]. If both wedges are placed at the same time, they will work one against the other, reducing the total teeth separation [4]. After each wedge placement, the gingival seal of the matrix is evaluated with an exploratory probe, followed by the band burnishing toward the adjacent tooth using the backside of a spoon excavator  blade (. Fig.  15.11f). This ensures that an adequate contact and contour of the band will be obtained. When used in association to circumferential matrices, some accessory techniques can help to obtain a good proximal contact when making composite restoration. They are based on the use of some contact forming instrument, to keep the matrix pressed toward the adjacent tooth, at the same time that a small increment of composite is light-cured, stabilizing the band in contact with the adjacent tooth. An in  vitro study showed that a handheld contact forming instrument resulted on a significant increase of the contact tightness, even though its effect is smaller to the one obtained with the use of a separation ring [24].

15.4.2.2 Circumferential Matrix

Contact Forming Instruments and Light Conducting Tips

 

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In general, the circumferential matrices are not the first choice to restore posterior teeth with composite, even on MOD preparations [4]. If the dentist excessively tightens a circumferential band around a tooth, a cuspal deflection of about 10–65 μm can happen, sometimes resulting in cracks or fractures of the remaining structure [17]. When restoring a single proximal surface, on MO or OD preparations, the double thickness of band, due to the presence of the strip on

 

 

 

The handheld contact forming instruments and the contact forming light conducting tips are designed to be pushed or pulled toward the direction of the contact, creating dental separating force through the matrix band, holding the composite in place during the light-curing procedure. Some examples of handheld contact forming instrument are Contact Pro 2 (Almore International), Trimax (AdDent),

605 Composite Restoration on Posterior Teeth

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..      Fig. 15.10  Use of handheld contact forming instrument. a–c Tooth preparation; d burnishing of the matrix over the paper mixing pad; e burnishing of the matrix toward the adjacent tooth; f acid etching; g application of the adhesive; h first increment placed on the gingival wall; i side view of the contact forming instruments Contact Pro 2 (Almore). The arrows show the flat area of the instrument handle. j view of the instrument tip showing the black line, which is a marginal ridge guide (red arrow), and the flat area of the handle (blues arrow); k light-curing of the composite holding the flat area (white arrow) parallel to the occlusal plane and pushing it against the matrix band

toward the proximal contact (red arrow). The marginal ridge guide is lined up with the tooth’s marginal ridge (yellow arrow); l a small impression in the composite is left on the gingival wall by the instrument; m, n application of oblique increments to restore the proximal surface; o matrix removal and placement of the first dentin shade oblique increment; p second dentin shade increment; q, r placement of enamel shade increments; s finishing with multi-bladed bur; t polishing with diamond polishing paste (Diamond Excel – FGM) and felt point (Felt FlexiPoint – Cosmedent); u final result

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..      Fig. 15.10 (continued)

607 Composite Restoration on Posterior Teeth

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..      Fig. 15.11  Use of the contact forming light conducting tip in the mesial preparation and a prepolymerized ball in the distal preparation. a Initial aspect; b–d tooth preparation; e matrix burnishing over a paper mixing pad; f wedge insertion on the mesial surface and burnishing of the band toward the adjacent tooth; g, h acid etching and application of the adhesive system; i first increment placed touching the matrix (GrandioSO – Voco); j contact forming light conducting tips (Light-Tip – Denbur): on the left the E-Type (truncated with elliptical tip) and on the right the C-Type (cone-­shaped with a circular tip); k light-curing using the tip, pulling the matrix toward the mesial surface (arrow); l impression left in the composite by the elliptical tip; m, n restoration of the proximal surface with oblique increments; o preparation and curing of a composite ball; p, q wedge

removal from the mesial interproximal space and insertion into the distal space. Placement of a composite increment on the gingival wall; r prepolymerized ball applied into the uncured composite layer, being pressed toward the gingival wall; s ball in position pushing the matrix strip toward the adjacent tooth; t restoration of the proximal surface with oblique increments of enamel shade composite; u shaping of the outer incline of the marginal ridge with a probe-shaped nib instrument, creating the occlusal embrasure; v finished proximal surfaces; w, x placement of oblique dentin shade increments; y increment corresponding to the triangular fossa on the inner incline of the marginal ridge, z, a´ increments of enamel shade composite; b´ finishing with multi-bladed bur; c´ polishing with silicon carbide brush; d´ final result

609 Composite Restoration on Posterior Teeth

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..      Fig. 15.11 (continued)

611 Composite Restoration on Posterior Teeth

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PerForm (Garrison), Forming XTS (Hu-Friedy), and OptraContact (Vivadent) (. Fig.  15.10h–l). The light conducting tips are clear plastic tips that are attached to the end of the light guide, allowing the matrix to be pressed and light-­ cured at the same time (. Fig. 15.11j–l). Some examples are the Light-Tip (Denbur) and Focu Tip (Hager). For all those options, firstly a thin steel matrix strip must be placed, wedged, and correctly burnished, according to what has already been described. When indicated, the wedge alternation technique should be applied. Then, a small horizontal layer of composite is placed on the preparation gingival wall. The handheld instrument or light conducting tip must be inserted inside this uncured composite and pushed toward the direction of the contact with the adjacent tooth, creating a separating force through the matrix at the exact place of the desired contact (. Fig. 15.10k and 15.11k). This layer is light-­ cured, creating a composite bridge that stabilized the matrix in contact with the adjacent tooth. The handheld instruments are available in two sizes, one for molars and other for premolars. In general, each end of the instrument is designed to a different proximal surface. When using the Contact Pro 2 instrument (Almore International), the anatomy of the contact is shaped and positioned ideally by holding the flat area of the instrument parallel to the occlusal plane (. Fig. 15.10j, k). At the tip of the instrument, there is a black line which is a marginal ridge guide (. Fig.  15.10j). According to the manufacturer’s instructions, this guide has to be aligned with the marginal ridge of the adjacent tooth while creating the contact (. Fig. 15.10k). The instrument is pressed toward the matrix band, applying enough force to slightly bend the instrument. The rounded ball at the center of the handle helps of the operator to apply force on the band. The light-curing guide of the curing device is held flat against the convex-shaped lens, and the light emission is started while maintaining the force. After curing, the instrument is gently rocked mesiodistally and lift out occlusally. Then, it can be seen the impression left by the instrument on the composite (. Fig.  15.10l and . 15.11l). The proximal wall must be finished with composite, using oblique increments. If there are two proximal boxes, wedge alternation technique should be used, restoring one proximal surface at each time. After finishing both proximal surfaces, the matrix can be removed and the occlusal box properly restored, like a Class I preparation. On the cases where the gingival wall is too deep, it is recommended to incrementally restore the deeper area with composite, pressing the matrix with the contact forming instrument before each light-curing. That will allow the creating of a proper proximal contour during the application of the composite, since the deeper regions of the preparation. A small impression of the instrument tip should be visible on the gingival wall after each layer, confirming contact of the composite with the instrument. When a flowable composite is used as the first layer, to allow a better adaptation to the preparation irregularities and work as a stress-absorbing layer, the contact forming instruments should also be used before its light-curing.  

 

 

 

 

 

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>> The contact forming instruments are designed to be pressed toward the direction of the contact, creating dental separating force through the matrix band, holding the composite in place during the light-curing procedure, and forming a composite bridge that stabilized the matrix in contact with the adjacent tooth.

Prepolymerized Ball Technique The prepolymerized ball or plunging ball technique is based on the use of a small ball of the cured composite to press the band, creating teeth separating force through the matrix, helping to obtain an appropriate proximal contact. For that, the tooth to be restored must receive a previously burnished matrix and wedge, as it has already been described. After the application of the adhesive system, it is necessary to produce a small composite ball, with a diameter a little bigger than the distance between the axial wall and the proximal surface of the adjacent tooth (. Fig. 15.11o–v). It can be prepared using powder-free gloves and then completely light-cured outside the mouth. After that, a thin layer of uncured composite is placed on the gingival wall of the preparation. The ball is then placed over this layer and pressed toward the gingival wall, using a hand instrument with a flat nib, such as an amalgam plugger. It is important to be sure that the ball entered tightly into the preparation, pressing the band toward the adjacent tooth, creating the desired teeth separation. The excess of composite over the ball is removed, and then a light-curing is performed. Then, the proximal surface is restored with oblique increments, until it reaches the height of the marginal ridge, shaping the outer incline of the marginal ridge with a probe-shaped nib instrument. On MOD preparations, each proximal box is restored separately, and the wedge alternation technique is used. The occlusal surface is restored using the stratified layering technique as already described.  

Ceramic Inserts The inserts are industrially prefabricated ceramic pieces with several shapes, sizes, and colors. The technique of ceramic inserts is a restorative procedure between the direct composite and the indirect ceramic restorations. One advantage of the use of the inserts is to reduce the bulk of composite needed to restore the tooth, therefore, reducing the amount of polymerization shrinkage and the final shrinkage stress. The inserts also reduce the thermal expansion of the restoration, since they have a CLTE lower than of composites. This characteristic can improve the marginal adaptation of the restoration in relation to those made only with composite. In addition, the use of some inserts on the proximal surface can also help the restoration of proximal contacts [14]. There are two basic kinds of inserts. One of them consists of inserts without specific instruments for the tooth preparation and was introduced in the dental market in 1991 by Bowen, the inventor of composites for tooth restorations [6]. They were named “megafillers” and were placed inside the non-cured composite to reduce the total volume of resin utilized. A reduction of the final composite content in a restora-

613 Composite Restoration on Posterior Teeth

tion up to 20% could be reached, through a good selection of shapes and number of inserts. The second kind of insert is based on the development of tooth preparation instruments that match the shape and size of the ceramic inserts. The preparation is performed with rotary or oscillatory instruments. After preparation, standardized inserts perfectly adapt to the cavities, like an indirect inlay, which are luted using flowable composite. The difference between the two types of inserts is the amount of composite necessary to finish the restoration. The maximum reduction is obtained when the inserts perfectly match the instruments for tooth preparation. It must be considered that, even though the restoration using insert technique could have some advantages in relation to the restorations only using composite, it takes longer to be performed, can require an additional removal of the remaining tooth structure, and is more expensive [14]. The SonicSys inserts (Vivadent) were made with ­leucite-­reinforced ceramic (. Fig. 15.12a–a´). The preparation system SonicSys Approx/SONICflex (Kavo) allows the preparation of symmetrical proximal cavities. The preparation points were selectively covered with diamond and available in three sizes, which perfectly match the ceramic inserts. They can be used for mesial and distal surfaces. The points have an active side covered by diamonds and a smooth side, which touches the proximal surface of the adjacent tooth. The beginning of the tooth preparation is performed with rotary instruments, followed by the standardization of proximal preparation with the oscillatory points of the selected size (. Fig.  15.12e–h). Then, the adhesive system is applied, followed by the matrix and wedge. A layer of flowable composite is applied, and the insert is placed in position; then a lightcuring is performed (. Fig. 15.12q–u). A very similar system called Cerana was produced by the Nordiska Dental, including conical inserts for the occlusal surface and proximal inserts of several sizes. It also presented diamond rotary instruments that match the shapes of the conical inserts, as well as oscillatory instruments with selective application of diamond for the proximal surface [14]. Although the use of ceramic inserts can produce very good restorations, its use has diminished in the recent years, due to the new direct composite technology, with low costs than an insert system. Therefore, most of the systems are no longer available on the market.  

 

 

15.4.2.3 Packable Composites and Low

Shrinkage Materials

The packable or condensable composites were created in the late 1990s, in an attempt to replace the silver amalgam as the main restorative material for posterior teeth, using a similar restorative technique. Those materials presented an extremely higher viscosity than the universal composites available, close to amalgam, to be condensed into the preparation using an amalgam plugger, which could press the matrix toward the adjacent tooth, helping to create the proximal contact. Despite the material stiffness contributes in forming tight contacts, a study showed that the matrix system applied is more effective than the composite viscosity for the final contact tightness result [24].

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Those composites cannot be considered as really condensable as amalgam, because they do not become denser when they are pressed into the preparation. The term packable is preferable for describing this class of materials. Due to its high viscosity, it was difficult to obtain perfect adaptation to the line and point angles, being recommended the use of an initial layer of a flowable composite [33]. In addition, the use of horizontal increments recommended by the manufacturers, like the ones used for the silver amalgam, was not adequate for composites. The simultaneous bonding to the buccal, gingival/ pulpal, and lingual walls increases stress generated by the high C-factor. Another negative aspect of the first packable composites was the higher surface roughness after polishing, in relation to the regular ones, due to its different filler technology. For this reason, its use was significantly reduced. Considering that shrinkage is one of the major drawbacks of composite materials and the main reason for restoration failures after short and long term, the researches and developments were focused on its reduction. The first attempt was to increase the filler content. Since the organic matrix was the responsible for the volumetric shrinkage, the lower the resin:filler ratio  in a composite, the lower the shrinkage would be. However, the increase in the filler content also increases the elastic modulus, creating stiffer materials. Although the total volumetric shrinkage was reduced, the shrinkage stress raised, impairing the marginal integrity and increasing all the other negative consequences related. This way, other options were attempted. As the methacrylate resins’ intrinsic shrinkage cannot be changed, exchanging the monomers seemed the most promising way to solve the shrinkage challenge. Therefore, low shrinkage monomers, such as the silorane (3 M Espe), were developed. On conventional methacrylate monomers, during the curing process, the monomers molecules have to approach their neighbours to form chemical bonds with them and create a polymer. This reaction leads to a significant volumetric shrinkage. According to the manufacturer, the polymerization process of silorane occurs through a cationic ring-opening reaction. In contrast to the linear reactive groups of methacrylates, the ringopening chemistry of the siloranes starts with the cleavage and opening of the ring system. This process gains space and counteracts the loss of volume which occurs in the subsequent step, when the chemical bonds are formed. In total, the ring-opening polymerization process yields a reduced volumetric shrinkage. According to the manufacturer, a volumetric shrinkage of about 1% and low shrinkage stress of about 2  MPa are generated, which represents a large reduction in relation to methacrylate-­ based material that shrinks up to 2–3% and generates shrinkage stress between 4 and 8 MPa. For this reason, the manufacturer recommended the use of horizontal increments, although without significant changes in the depth of cure. Even though presented many advantages, the silorane-­based materials needed a specific and compatible adhesive system, being more difficult to repair the old restorations. The material did not provide a great shade options and was more expensive than the regular ones. After some year, it was also removed from the market, being replaced by the new bulk-fill materials.

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..      Fig. 15.12  Proximal restoration with ceramic insert (SonicSys Approx – Vivadent). a Oscillatory instruments that match the shape and size of the ceramic inserts; b ceramic inserts compatible with preparation instruments; c fractured amalgam restoration; d defective restoration removed; e, f standardization of proximal box shape with the sonic instrument; g, h preparation shape standardized; i removal of remaining carious dentin tissue with round bur in low speed; j preparation completed; k-m fitting test of the insert; n insertion of the

matrix and wedge; o acid etching; p application of the adhesive system; q placement of a small layer of flowable composite on the walls; r application of the adhesive on the insert; s–u insert placement; v matrix and wedge removal. Proximal surface restored; w placement of dentin shade composite in the occlusal box; x placement of enamel shade composite; y finishing and shaping of the ceramic insert with a fine grit diamond point; z polishing with silicon carbide brush; a´ restoration completed

615 Composite Restoration on Posterior Teeth

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617 Composite Restoration on Posterior Teeth

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15.4.2.4 Bulk-Fill Composites

Although the layering technique can provide very good restorations, reducing the negative effects of the shrinkage stress, it can be a little tricky and time-consuming, especially on deep preparations. Therefore, most dentists would like to have a simpler way to restore posterior teeth. The more recent researchers were focused on creating a material that could overcome these problems, allowing a quicker restorative procedure. The two main reasons for using the layering technique are the shrinkage stress and the depth of cure of the universal composites. The first reason makes necessary to use oblique increments, to reduce the stress over the bond inter-

face and remaining tooth structure, while the second one obliges the use of a maximum 2 mm thick layers, for reaching a good curing on the bottom of the material. Different strategies were created by the manufactures to modify these two important characteristics, producing materials that can be used in horizontal and thicker increments, which were named bulk-fill composites. Analyzing the organic matrix of the dental composites, shrinkage stress is mainly determined by the total volumetric shrinkage, the internal flowability of the material, and the polymerization kinetics (polymerization speed). A highly shrinking material with a small internal flowability and very

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fast curing speed will exhibit the highest shrinkage stress. This way, manufacturers created new special monomers and polymerization modulators for reducing the final stress. In the Admira Fusion X-tra (Voco) restorative material, the organically modified ceramic (Ormocer) is an oligomer with an inorganic backbone and many polymerizable organic groups, which reduces the volumetric shrinkage due to its inorganic structure and the bigger molecular weight. Filtek Bulk Fill (3  M Espe) contains an addition-fragmentation monomer (AFM). According to the manufacturer, during polymerization the AFM reacts to create a polymer as any methacrylate, including the formation of crosslinks between adjacent polymer chains. However, it contains a special reactive site that cleaves through a fragmentation process during polymerization. This provides a mechanism for the relaxation of the developing network and subsequent stress relief. SureFil SDR (Dentsply) has a polymerization modulator chemically embedded in the polymerizable resin backbone of the monomer. It reduces stress buildup on polymerization without a reduction in the polymerization rate or conversion. The resin forms a more relaxed network and provides significantly lower polymerization stress than the conventional resin. >> The shrinkage stress is mainly determined by the total volumetric shrinkage, the internal flowability of the material, and the polymerization kinetics (polymerization speed). A highly shrinking material with a small internal flowability and very fast curing speed will exhibit the highest shrinkage stress.

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In relation to the depth of cure, it is determined by three different factors, which are the monomers, the initiator system, and the opacity and shade of the composite. The bulk-­fill materials are more translucent than the regular composites, which allow higher light transmission through the material, resulting in adequate polymerization on the bottom of thicker layers. The depth of cure of bulk-fill materials is around 4–5 mm, in contrast to the 2 mm of the regular composites.

a

The bulk-fill materials can be classified into two groups. The first is the base material, which is flowable and used to restore the internal and proximal parts of the tooth preparation. They have lower filler content than the corresponding universal composites and low esthetics. Therefore, the external occlusal surface must be covered with a 2 mm capping layer of regular composite. Some examples are SureFil SDR (Dentsply), Filtek Bulk Fill flow (3 M), Admira Fusion X-base (Voco), and Venus Bulk fill (Kulzer) (. Fig. 15.13a). The second group is the full restorative material,  represented by regular viscosity composites, indicated to completely fill the preparation without any capping. Some examples are Admira Fusion X-tra (Voco), Beautiful Bulk (Shofu), Ecosite Bulk Fill (DGM), and Filtek Bulk Fill Posterior (3  M Espe) (. Fig. 15.13b).  

 

>> The bulk-fill composites can be classified as base or full restorative materials. The former are flowable and used to restore the inner parts of the preparation, being capped with a layer of a normal composite. The latter have regular viscosity and are indicated to completely fill the cavity.

When performing restorations with bulk-fill materials, special attention should be given to the emittance of the lightcuring unit. The increased depth of cure of these materials, claimed by the manufacturers, is always calculated considering certain power emitted from the light-curing unit and a certain curing time, as described in 7 Chap. 13. The use of a radiometer or another method to control the emittance is advised. The instructions of each manufacturer must be followed, and an additional curing through the buccal and lingual surfaces is always recommended. Before starting, the preparation depth should be measured using a periodontal probe, on the deepest area of the cavity. If it is equal or smaller than the depth of cure recommended by the manufacturer, a single increment of bulk full restorative material can be used. When the preparation depth is deeper, the first layer can be the maximum recommended by the manufacturer, followed by other layers until com 

b

..      Fig. 15.13  Bulk-fill composites. a Base materials that require capping with standard composite; b restorative composites with regular viscosity

619 Composite Restoration on Posterior Teeth

pletely fill the preparation. For the base materials, a minimum space has to be left for the capping composite. . Figure  15.14 shows the restorative procedure using a base bulk-fill flowable composite. The sectional matrix and separation ring are placed, and the adhesive applied. Then, the flowable base composite is applied directly from the compule into the preparation using a syringe, with slow and steady pressure. The application starts in the deepest areas,  

maintaining the tip close to the material surface and gradually withdrawing, as the preparation is filled, up to 4  mm thick increment or 2 mm short of the cavosurface margin. In case of overfill or excess on occlusal margins, a flocked applicator tip wetted with residual adhesive can be used to remove excess. This layer is light-cured according to the manufacturer recommendations. As the base composites are more translucent, if placed on the occlusal cavosurface margins or

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..      Fig. 15.14  Restoration using flowable bulk-fill base composite. a Initial aspect; b carious tissue removed; c pulpal protection with GIC; d, e acid etching and adhesive system application; f placement and burnishing of sectional matrix; g, h restoration of the buccal surface on distal box with nanohybrid composite (Esthet-X HD – Dentsply); i Compules of SureFil SDR – Dentsply; j, k filling 4 mm of the prepara-

tion with flowable composite, leaving space for the occlusal capping; l restoration of the proximal surface with nanohybrid composite; m placement of sectional matrix on the mesial box; n, o application of flowable composite filling 4 mm of the preparation; p restorations of proximal surface; q finished proximal surfaces; r finished restoration after capping and groove characterization

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621 Composite Restoration on Posterior Teeth

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on the buccal margins of a large proximal box, the restorative material will be visible while the patient is talking or smiling, adversely affecting the esthetic result. In case a very dark sclerotic dentin is present, an opaque tint may be applied over the adhesive layer, previously the composite placement. Due to the low viscosity, the flowable composites will not press the matrix toward the adjacent tooth. This way, the proximal contact will totally depend on the matrix and wedge system. For this reason, the sectional matrices with separation ring are recommended. If necessary, complementary technique as contact forming instruments or others can be used.

ment with a flat- or round-shaped nib, like a plugger. On the last layer, the matrix is pressed over the surface of access, and the light-curing is performed through the strip. 15.4.4 

 sthetic Improvement of Amalgam E Restorations

Sometimes the patients have large and old amalgam restorations in good conditions, but that are visible while talking or smiling, negatively interfering on the esthetics. On this case, instead of replacing the entire restoration, which can result on the additional removal of the remaining tooth structure, a small preparation can be performed inside the visible part of the amalgam, and a composite veneer used to hide the metal 15.4.3  Restoration of Proximal Lesions (. Fig.  15.16a–i). First, a prophylaxis is performed using through Buccal/Lingual Access pumice and brush to remove extrinsic stains. The anesthesia On preparations with buccal or lingual access, after isolation is not generally necessary since the preparation will be done of the operating field, a clear plastic matrix strip should be mainly on the metal and enamel. When the metal extends placed and wedged, which allows the composite to be light-­ beyond the gingival margin, the level of the gingival tissue is cured through the band (. Figs.15.15 and 15.16c–f). The pad marked on the restoration with a sharp probe, placing a of the index finger is placed on the tooth surface, opposite to retraction cord inside the gingival sulcus. The preparation is the preparation access, holding the matrix in contact with the performed until the marked level. A round carbide bur or surface and avoiding the overflow of the composite. The diamond point is used to cut the amalgam, removing a material must be placed inside the preparation using a layer- homogeneous depth layer of about 1.5 mm, entering the ing technique, employing a nonstick composite filling instru- embrasures only enough to hide the metal. Retentive coves  

 

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..      Fig. 15.15  Proximal restoration through buccal access. a Proximal lesion close to the buccal surface; b protection of the adjacent tooth and tooth preparation; c, d application of acid and adhesive system; e placement of clear plastic strip and wedge; f polished restoration

are prepared on the gingivoaxial angle and slots on the axial wall inside the metal. A bevel on enamel is performed to mask the restoration margin and improve the retention [33]. The preparation is acid etched to clean the surface and create microretention on beveled enamel, and the adhesive system applied. A thin layer of opaque tint must be applied over the adhesive layer to mask the metal shade. The opaque is more effective when applied in thin layers and light-cured separately. Then, an opaque dentin shade composite is applied over the tint, helping to mask its white color, being covered with an enamel shade composite (. Fig. 15.16f–i).  

15.4.5 

 epair of Ceramic or Composite R Restorations

The indirect ceramic/composite restorations or crowns, as well as direct composite restorations, can undergo small cracks or fractures in the oral environment due to mechanical load (. Fig. 15.17a–i). On those cases, the composite is an excellent option for repairing them instead of its total replacement. Before starting the repair, the dentist should determine and control the cause of the fracture and, whenever possible, the type of restorative material used in the restoration. The  

623 Composite Restoration on Posterior Teeth

vitreous ceramics can be etched with hydrofluoric acid gel to improve the composite bonding. However, the non-vitreous ceramics, such as those based on zirconium or alumina, are not significant affected by this etching [31]. First, prophylaxis has to be performed to remove stains and biofilm. The fractured area can be removed or a small preparation performed on the fracture line, such as double bevel using a round diamond point. The surface of vitreous ceramics must be etched with 10% hydrofluoric acid gel for the time recommended by the acid manufacturer, followed

by copious washing and air drying. Then, a silane coupling agent is applied for 1 min, which also must be dried with air. After that the adhesive system is applied and light-cured, followed by the composite application and shaping. If there is enamel on the interface, close to the fractured area, it must never be etched with hydrofluoric acid, because it is too strong and the products generated by the reaction will deposit on the etched ceramic surface, adversely affecting the bonding. The enamel must be only etched with a phosphoric acid gel.

a

b

c

d

e

f

..      Fig. 15.16  Composite veneers in old amalgam restorations. a Initial aspect; b preparation on the buccal surface and mechanical retentions; c bevel in enamel margin; d, e etching and application of the adhesive

system; f placement of a thin layer of opaque tint over the amalgam; g placement dentin shade composite (Z350 XT – 3 M Espe); h use of clear matrix to shape the enamel shade composite; i final result

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g

h

i ..      Fig. 15.16 (continued)

15

a

..      Fig. 15.17  Repair of a fractured ceramic crown. a Initial aspect; b removal of the fractured area; c etching with hydrofluoric acid gel; d aspect after etching; e Application of silane; f application of the

b

adhesive system; g ceramic ready for the composite placement; h composite applied; i result immediately after removal of rubber dam

625 Composite Restoration on Posterior Teeth

c

d

e

f

g

h

i

..      Fig. 15.17 (continued)

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In case of composite restorations, the fractured area must be roughened by abrasion, with a coarse grit diamond point or sandblasting with aluminum oxide particles, creating micromechanical retention [3]. The surface is etched with phosphoric acid for cleaning and the adhesive system applied, followed by the composite placement. If any dentin is exposed on the fractured area, the proper bonding technique to this substrate must be used. 15.5 

Finishing and Polishing

mark the centric contacts once more. The presences of interferences during disocclusion movements are analyzed. All the contacts marked in red over the composite are removed because they represent contacts during the excursive movements, which should not happen. The centric contact in black must not be changed. The procedure is repeated once again to evaluate if no interferences have remained. For the occlusal adjustment and excess removal on the margins, in the occlusal surface, round- or pear-shaped fine grit diamond points or multi-bladed burs can be used (. Fig. 14.65a, b) [33]. Aluminum oxide mounted stones can also be used (. Fig. 4.28a). The shape of the rotary instrument must be compatible to the surface that is intended to be adjusted (. Figs. 15.6b´, 15.7x, 15.9s).  

 

15

Ideally, no finishing and polishing should be required to a new restoration, because the shape and surface smoothness of the last composite layer applied should be perfect. However, it is extremely hard to shape a perfect and functional tooth anatomy, without evaluating the patient’s occlusion. This way, almost always some adjustment will be required, even if minimum. The friction of rotary cutting or abrasive instrument over the composite produces mechanical and thermal aggression. This creates microcracks on the composite surface with depth between 25 and 50 μm, which can adversely affect the wear of the restoration [4, 8]. Every effort must be done to avoid and/or minimize the need for rotary instruments [4]. Whenever necessary to correct the restoration’s anatomy and remove excess of composite, the finishing procedure can be started immediately after the light-curing. It has to be performed with proper instruments, requiring ability and knowledge about the correct dental anatomy [33]. Preferably, the finishing of the margins should be performed before removing the rubber dam isolation [4]. Excess or lack of the material can be detected with the tip of an exploratory probe touching the surface, moving from the tooth to the restoration and vice versa, on the entire cavosurface margin. Excess of material must be removed but avoiding undesirable wear of the remaining tooth structure [4]. After that, the occlusion should be evaluated and premature contacts removed. A double-sided two-color articulating paper (e.g., black and red) is held with a Miller forceps, in a way that the black side is facing the restored tooth. First, the centric contacts are analyzed, asking the patient to close the mouth in centric occlusion and open it again. It has to be evaluated if the contacts on adjacent teeth, which existed before the preparation, can be seen now. If only the restoration is in contact with the opposite tooth, just the marked contact place must be grinded, and the articulating paper used again. Those steps are repeated as many times as necessary, until the original contacts of the adjacent teeth reappear, but keeping a contact on the restored tooth. To analyze the presence of interferences during excursive movements, the paper is placed again on the paper forceps, in a way that the red side is facing the restored tooth. The patient is asked to occlude at centric occlusion and perform protrusive and lateral movements of the mandible to detect any contact. After that, the patient opens the mouth, and the black side of the paper is turned in the forceps. He is asked to close on centric occlusion again to

 

Tips

The occlusal adjustment of the restoration must be performed analyzing the centric contacts and those during excursive movements of the mandible.

The rotary instruments should not remove enamel from the margins, avoiding touching it, and the composite must not be excessively grinded [33]. After finishing, the restoration must have the ideal shape to allow masticatory function, without overhangs on the gingival margins, which may promote biofilm deposition and gingival inflammation. The evaluations of proximal surface smoothness and contact tightness are performed with dental floss, wrapping the proximal restored surface with the floss, moving it gingivoocclusally. If the matrix and wedge were correctly placed and the restoration has not overhangs, there is no need to polish the proximal area, because the restoration has copied the matrix strip smoothness [4]. It there is gingival overhangs, they can be removed using the coarse grit side of an abrasive strip. To avoid undesired grinding of the proximal contact, narrow strips should be employed. It can also be used for this purpose the stainless-­ steel serrated strip saw (. Fig.  15.18f). The marginal ridges and buccal/lingual/occlusal embrasures may be finished with small abrasive disks or flame-shaped burs or points (. Fig. 15.18c, d). On the buccal and lingual embrasures, the contour carbide carvers or No. 12 scalpel blade are also good options (. Fig. 15.18a, b). A study proposed a supplemental polymerization after the end of finishing procedures, since the composite surface that was close to the light-guide tip, and therefore with the best mechanical properties, was removed [38]. The polishing may be performed using abrasive rubber points or cups (. Figs. 15.7y and . 15.9t). There are single or multiple steps abrasive rubber points. On the latter, the coarse grit rubber is used first, which is gently applied over the surface with intermittent movement, until a homogeneous surface roughness is obtained. The area must be washed and dried to remove abrasive residues, and the fine grit rubber is employed. The marginal ridge on occlusal  

 

 

 

 

627 Composite Restoration on Posterior Teeth

a

b

c

d

e

f

..      Fig. 15.18  Instruments for finishing proximal surfaces. a Contour carbide carver (TZC12 – Thompson/Miltex); b use of contour carbide carver in the embrasure area; c finishing of embrasures with the abrasive disks (Diamond PRO – FGM); d outer incline of the marginal

ridge being finished with a multi-bladed bur; e abrasive strip placed below the proximal contact; f serrated strip saws attached to the holders (1, strip holder (Coraldent); 2, Microcut (TDV))

embrasure and buccal and lingual embrasures can be polished with the fine abrasive disk. A felt point (Felt FlexiPoint, Cosmedent) associated with aluminum oxide or diamond polishing paste can also be employed (. Fig. 15.10t). Another possibility is the use of silicon carbide brushes, which the abrasive particles are embedded in the bristles. As the bristles wear down, fresh abrasive particles are released (. Fig. 15.6c´, d´, . 15.12z). It has different shapes to adapt to various tooth surfaces. The abrasive rubber spiral wheels are also a good option, adapting to all surfaces (. Fig. 4.29d). The correctly

finished and polished restoration must simulate the smoothness of the dental tissue and not be noticed by the patient or cause irritations to the tongue and oral mucosa. If the proximal surface has been finished, it must be polished with the fine grit abrasive strip. It is large the number of composite restorations inadequately finished and polished, most times due to the fact that the dentist and patient are tired at the end of the restorative procedure. This way, the composite should be polished on a later appointment, when it will be possible a more detailed

 

 

 

 

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evaluation of what must be done. In addition, the clinician may have some difficulties to distinguish the interface between composite and the preparation, problems of access and visibility, and lack of know-how about the use of the instruments, material, and techniques. A study showed that to finish and polish a restoration on a later appointment also improves the wear resistance of the composite [16]. This is related to the fact that, immediately after curing, the composite has not yet reached its maximum degree of conversion and physical properties, important to bear the stress generated by the rotary instruments. The called “dark-curing” phase following application of light-curing continues up to 24 h. Tips

Whenever possible, the finishing and polishing of a composite restoration should be postponed for the next dental appointment.

15.6 

15

Surface Sealing

The microcracks created on composite surface, by finishing and polishing procedures, can work as a path for the penetration of water, acids, and other substances available in the oral cavity, coming from the human diet and bacterial metabolism. Those substances soften the resin matrix and increase the wear. A clinical study showed that finishing and polishing procedures may increase up to 46% the wear rate of some composites, in relation to when it was not performed [16]. The finishing and polishing may also increase the marginal gaps formed during the polymerization [4]. In an attempt to control this problem, a procedure called surface sealing, rebonding, or post-bonding was proposed. It consists of the application of a liquid resin over the composite, like an adhesive, that penetrates and seals the microcracks [4]. Some studies showed that this procedure is effective to clinically reduce the wear rate, even though its effect lasts for only 6 months and a new application is necessary [13, 45]. Besides sealing the microcracks on the composite surface, it can also help to seal the cracks that may occur on the enamel surface, close to the restoration margin, due to the shrinkage stress, as well as the marginal gaps [4, 33]. For that, acid etching of the composite surface and tooth structure 1–2 mm beyond the margins is performed for 15 s, followed by rinsing with air/water spray and drying with airstream. The surface sealant is applied, followed by an airstream to produce a very thin coat and light-curing for 10 s. The product used for surface sealing is a dedicated material, basically an unfilled solvent-free monomer blend, and not a regular adhesive or pit and fissure sealant. The surface sealing technique may be observed in . Fig. 15.6e´–g´.  

Tips

The surface sealing can fill the microcracks on composite surface, enamel cracks close to the margin and interfacial gaps, reducing the wear and increasing the durability of the restoration.

15.7 

 aintenance of Posterior Composite M Restorations

When correctly indicated and performed, in a patient with good oral health, composite restorations may show excellent durability. The correct advice about restoration maintenance, oral hygiene, dietary control, and use of fluoride must be given to the patient during the dental treatment [4]. In addition, composite restorations must be frequently reevaluated by the dentist to detect any problems, such as material chips, bulk fractures, or marginal ditching. The patient can return to the dental office every 6 months for evaluation and surface sealing. Patients that intake large amounts of coffee and ­carbonated or alcoholic beverages must be aware of their higher risk of restoration wear and staining [43]. Whenever possible, small defects on composite restorations can be repaired by adding new material, since the remaining restoration is in good conditions. However, before performing a repair, the factor that caused the defect should be determined and controlled. The repair technique was already described in this chapter. When the defect is located on the proximal surface, a small preparation is done to allow access to new composite placement. A matrix and wedge must be applied, like for any restoration. There are on the market some adhesives developed specifically for composite restorations repair, such as Ecusit (DMG). However, most adhesives can be used to restoration repair, since the manufacturer’s instructions are followed. For many years, every dental composite and adhesives were based on methacrylate monomers, which means that they were all chemically compatible and could be used for restoration repair. However, the silorane monomers do not properly bond to methacrylate-based composites and vice versa. Therefore, restorations made with this material should be repaired with the same composite and with silorane adhesive [5]. A great concern is the fact that the dentist, who will perform the repair of an old restoration, may not be the same to the one who originally did it and does not know which material was used. For this reason, the composite surface must always be roughen by abrasion, with a coarse grit diamond point or sandblasting, creating micromechanical retention in an attempt to increase the bonding [3].

629 Composite Restoration on Posterior Teeth

Conclusion The composite resin is the most widely used restorative material for posterior teeth. The success of this kind of restoration is related to the dentist’s understanding about the material’s properties, following its indications, but respecting its limitations. The tooth preparation procedure should always focus on the maximum preservation of the remaining tooth structure, associated with a meticulous restorative technique. Different strategies for proper restoration of proximal contour and contact can be used, including preoperative and alternation wedging, sectional matrix and separation rings, contact forming instruments, prepolymerized ball, etc. The use of layering technique is essential for regular composites; however, the new bulk-fill materials are a quicker and viable option. The finishing and polishing techniques are also important for the quality and durability of the restoration, although neglected by many clinicians. The dentist must attempt to avoid unnecessary restoration replacement, trying to repair the old ones whenever possible.

References 1. Alomari QD, Reinhardt JW, Boyer DB. Effect of liners on cusp deflection and gap formation in composite restorations. Oper Dent. 2001;26:406–11. 2. Anusavice KJ. Phillips science of dental materials. 11th ed. St. Louis: Elsevier; 2011. 3. Badra VV, Faraoni JJ, Ramos RP, Palma-Dibb RG. Influence of different beverages on the microhardness and surface roughness of resin composites. Oper Dent. 2005;30:213–9. 4. Baratieri LN, Monteiro Junior S, Andrada MA, Ritter AV.  Odontologia Restauradora: Fundamentos e Possibilidades. São Paulo: Santos; 2001. 5. Barcellos D, Plefken P, Torres C, Pucci C, Pagani C. Composite repair bond strength: Dimethacrylate-based and silorane-based composites. J Adhes Dent. 2011;36:281–92. 6. Bowen RL, Eichmiller FC, Marjenhoff WA.  Glass-ceramic inserts anticipated for “megafilled” composite restorations. Research moves into the office. J Am Dent Assoc. 1991;122:71, 73, 75. 7. Causton BE, Miller B, Sefton J. The deformation of cusps by bonded posterior composite restorations: an in  vitro study. Br Dent J. 1985;159:397–400. 8. Celik EU, Ergücü Z, Türkün LS, Ercan UK. Tensile bond strength of an aged resin composite repaired with different protocols. J Adhes Dent. 2011;13:359–66. https://doi.org/10.3290/j.jad.a19651. 9. Cenci MS, Lund RG, Pereira CL, de Carvalho RM, Demarco FF. In vivo and in vitro evaluation of Class II composite resin restorations with different matrix systems. J Adhes Dent. 2006;8:127–32. 10. Chen L, Suh BI, Yang J. Antibacterial dental restorative materials: a review. Am J Dent. 2018;31:6B–12B. 11. Collins CJ, Bryant RW, Hodge KL.  A clinical evaluation of posterior composite resin restorations: 8-year findings. J Dent. 1998;26:311–7. 12. Demarco FF, Cenci MS, Lima FG, Donassollo TA, André D de A, Leida FL.  Class II composite restorations with metallic and translucent matrices: 2-year follow-up findings. J Dent. 2007;35:231–7. https:// doi.org/10.1016/j.jdent.2006.07.011. 13. Dickinson GL, Leinfelder KF, Mazer RB, Russell CM. Effect of surface penetrating sealant on wear rate of posterior composite resins. J Am Dent Assoc. 1990;121:251–5.

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14. Federlin M, Thonemann B, Schmalz G. Inserts–megafillers in composite restorations: a literature review. Clin Oral Investig. 2000;4:1–8. 15. Fejerskov O, Kidd EAM.  Dental caries: the disease and its clinical management. Oxford: Blackwell Munksgaard; 2008. 16. Glasspoole E, Erickson R. The effect of finishing time on wear resistance of composites. J Dent Res. 1989;68:207. 17. Hood JA. Biomechanics of the intact, prepared and restored tooth: some clinical implications. Int Dent J. 1991;41:25–32. 18. Ikemi T, Nemoto K. Effects of lining materials on the composite resins shrinkage stresses. Dent Mater J. 1994;13:1–8. 19. Imazato S, Ma S, Chen J, Xu HHK. Therapeutic polymers for dental adhesives: loading resins with bio-active components. Dent Mater. 2014;30:97–104. https://doi.org/10.1016/j.dental.2013.06.003. 20. Jefferies SR. Bioactive and biomimetic restorative materials: a comprehensive review. Part I.  J Esthet Restor Dent. 2014;26:14–26. https://doi.org/10.1111/jerd.12069. 21. Kitagawa H, Miki-Oka S, Mayanagi G, Abiko Y, Takahashi N, Imazato S.  Inhibitory effect of resin composite containing S-PRG filler on Streptococcus mutans glucose metabolism. J Dent. 2018;70:92–6. https://doi.org/10.1016/j.jdent.2017.12.017. 22. Lacy AM.  A critical look at posterior composite restorations. J Am Dent Assoc. 1987;114:357–62. 23. Loomans BAC, Opdam NJM, Roeters FJM, Bronkhorst EM, Burgersdijk RCW. Comparison of proximal contacts of Class II resin composite restorations in  vitro. Oper Dent. 2006;31:688–93. https://doi. org/10.2341/05-133. 24. Loomans BAC, Opdam NJM, Roeters JFM, Bronkhorst EM, Plasschaert AJM.  Influence of composite resin consistency and placement technique on proximal contact tightness of Class II restorations. J Adhes Dent. 2006;8:305–10. 25. Lutz E, Krejci I, Oldenburg TR. Elimination of polymerization stresses at the margins of posterior composite resin restorations: a new restorative technique. Quintessence Int. 1986;17:777–84. 26. Lutz F, Krejci I, Luescher B, Oldenburg TR. Improved proximal margin adaptation of Class II composite resin restorations by use of light-reflecting wedges. Quintessence Int. 1986;17:659–64. 27. Mair LH. Ten-year clinical assessment of three posterior resin composites and two amalgams. Quintessence Int. 1998;29:483–90. 28. McCabe J, Yan Z, Al Naimi O, Mahmoud G, Rolland S. Smart materials in dentistry. Aust Dent J. 2011;56:3–10. https://doi.org/10.1111/ j.1834-7819.2010.01291.x. 29. McCullock AJ, Smith BG. In vitro studies of cuspal movement produced by adhesive restorative materials. Br Dent J. 1986;161:405–9. 30. Miki S, Kitagawa H, Kitagawa R, Kiba W, Hayashi M, Imazato S. Antibacterial activity of resin composites containing surface pre-­ reacted glass-ionomer (S-PRG) filler. Dent Mater. 2016;32:1095–102. https://doi.org/10.1016/j.dental.2016.06.018. 31. Mopper KW, O’Malley M.  The illustrated technique guide for renamel restorative system. Chicago: Cosmedent; 1994. 32. Porto ICC de M, Soares LES, Martin AA, Cavalli V, Liporoni PCS. Influence of the photoinitiator system and light photoactivation units on the degree of conversion of dental composites. Braz Oral Res. 2010;24:475–81. 33. Roberson TM, Heymann H, Swift EJ. Sturdevant’s art and science of operative dentistry. 5th ed. St. Louis: Mosby; 2006. 34. Roberson T, Heymann H, Swift E. Art and science of operative dentistry. Mosby/Elsevier; St. Louis 2011. doi:https://doi.org/10.1111/ phpp.12129. 35. Roulet JF.  Benefits and disadvantages of tooth-coloured alternatives to amalgam. J Dent. 1997;25:459–73. 36. Saber MH, Loomans AC, El Zohairy A, Dörfer CE, El-Badrawy W. Evaluation of proximal contact tightness of Class II resin composite restorations. Oper Dent. 2010;35:37–43. https://doi.org/10.2341/09-037L.

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37. Schmidlin PR, Huber T, Göhring TN, Attin T, Bindl A. Effects of total and selective bonding on marginal adaptation and microleakage of Class I resin composite restorations in vitro. Oper Dent. 2008;33:629– 35. https://doi.org/10.2341/07-158. 38. Simonsen RJ, Kanca J. Surface hardness of posterior composite resins using supplemental polymerization after simulated occlusal adjustment. Quintessence Int. 1986;17:631–3. 39. Skinner EW.  A comparison of the properties and uses of silicate cement and acrylic resin in operative dentistry. J Am Dent Assoc. 1959;58:27–36. 40. Stein PS, Sullivan J, Haubenreich JE, Osborne PB. Composite resin in medicine and dentistry. J Long-Term Eff Med Implants. 2005;15: 641–54. 41. Tay FR, Hashimoto M, Pashley DH, Peters MC, Lai SCN, Yiu CKY, et  al. Aging affects two modes of nanoleakage expression in bonded dentin. J Dent Res. 2003;82:537–41. https://doi. org/10.1177/154405910308200710. 42. Tolidis K, Nobecourt A, Randall RC. Effect of a resin-modified glass ionomer liner on volumetric polymerization shrinkage of various composites. Dent Mater. 1998;14:417–23.

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43. Torres A, Pagani C, Araujo M. Selamento de superfície em restaurações de resina composta: Avaliação clínica e de modelos de estudo. Pós Gr Rev Fac Odontol São José Dos Campos. 2000:3–13. 44. Versluis A, Tantbirojn D, Douglas WH. Do dental composites always shrink toward the light? J Dent Res. 1998;77:1435. https://doi.org/1 0.1177/00220345980770060801. 45. Wisniewski J, Leinfelder K, Thomas J.  Effect of finishing on the in  vivo wear rate of a posterior composite resin. J Dent Res. 1990;69:161. 46. Yoneda M, Suzuki N, Masuo Y, Fujimoto A, Iha K, Yamada K, et  al. Effect of S-PRG eluate on biofilm formation and enzyme activity of oral bacteria. Int J Dent. 2012;814913:2012. https://doi. org/10.1155/2012/814913. 47. Zhang S, Kern M. The role of host-derived dentinal matrix metalloproteinases in reducing dentin bonding of resin adhesives. Int J Oral Sci. 2009;1:163–76. https://doi.org/10.4248/IJOS.09044. 48. Statement on posterior resin-based composites. ADA Council on Scientific Affairs; ADA Council on Dental Benefit Programs. J Am Dent Assoc. 1998;129:1627–8.

631

Preventive Measures and Minimally Invasive Restorative Procedures Alessandra Bühler Borges, Carlos Rocha Gomes Torres, and Nadine Schlueter 16.1

Introduction – 632

16.2

Preventive Measures – 632

16.2.1 16.2.2 16.2.3 16.2.4

 utrition – 632 N Oral Hygiene – 634 Fluorides – 636 Additional Caries Preventive Strategies – 640

16.3

Pit and Fissures Sealants – 642

16.3.1 16.3.2 16.3.3

T ype of Sealants – 645 Longevity of the Sealants and Effect on Incidence of Caries – 650 Extended Fissure Sealant and Conservative Composite Restorations – 650

16.4

Enamel Caries Infiltration – 652 References – 660

© Springer Nature Switzerland AG 2020 C. R. G. Torres (ed.), Modern Operative Dentistry, Textbooks in Contemporary Dentistry, https://doi.org/10.1007/978-3-030-31772-0_16

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Learning Objectives The learning objectives of this chapter are related to the following topics: 55 Basic information on types of preventive measures 55 The principles of prevention in dentistry 55 Relevance of nutrition recommendations with respect to caries 55 Relevance of oral hygiene (mechanical plaque control) with respect to caries 55 Principles of fluoridation – effects, types, and preparations 55 Measures for chemical plaque control 55 Principles of fissure sealing 55 Principles of caries infiltration

16.1

16

Introduction

The objectives of operative dentistry are to prevent, preserve, and maintain the sound tooth structures and to minimize the tooth structure removal required, if necessary, for restorations. The minimally invasive dentistry is part of a developmental progress, determined by the accumulation of information from the cariology that involves the knowledge of the caries disease, as well as the developing of techniques and mechanisms aiming to prevent or arrest the lesion. It is currently known that dental caries is an in part reversible disease that begins with enamel demineralization and it may, eventually, progress up to a cavitation if the risk factors are not controlled and if no preventive measures are implemented [1]. The minimally invasive dentistry involves procedures such as pit and fissure sealants, resin infiltration, and conservative composite restorations. Together with the preventive measures, as dietary advices, regular control of biofilm, and improvement of oral hygiene habits as well as the application of lowly and highly concentrated fluorides to improve remineralization and to decrease demineralization, those procedures may reduce caries development and preserve the sound tooth structure [2]. 16.2

Preventive Measures

Prevention in dentistry is one of the keystones in the daily practice of each dentist. The preventive strategies are traditionally divided into primary, secondary, and tertiary preventive measures [3, 4]. The primary strategies aim to reduce the number of new cases of a disease. This is normally achieved by health-promoting strategies. For cariology such strategies include nutrition advices, oral hygiene recommendations, inhibition of demineralization by application of fluorides, and the application of fissure sealants. In the context of secondary prevention, all measures are subsumed, which aim to early detect a disease, preferably at a stage at which the disease can be reversed or even healed. The major goal is to avoid any additional coming down with the disease and to

limit the dental hard tissue loss. These measures include application of fluoride preparations to enhance the remineralization process and the infiltration of carious lesions. The tertiary prevention that includes all measures specifically treating defect oriented the sequelae of the disease aiming to prevent further damage. This includes extended fissure sealing, minimally invasive approaches as well as adequate treatment techniques, such as use of restorative  materials. All measures, preventive and restorative, should be accompanied by the consideration of all factors potentially influencing the disease, such as caries activity, caries risk, nutrition habits, oral hygiene habits and devices, fluoride usage, socioeconomic status, age, etc. The four major parts of caries prevention comprise advices regarding “nutrition,” “oral hygiene” (including mechanical and chemical biofilm control), “fluorides,” and also the “visits to the dentist” (including the application of fissure sealants) [5]. These parts are substantiated by the local legal framework for health promotion. Most evidence for these measures exists for fluorides, followed by oral hygiene advices and least for nutrition [6–10]. >> Prevention can be divided into primary, secondary, and tertiary prevention. The four major parts of caries prevention comprise advices regarding “nutrition,” “oral hygiene” (including mechanical and chemical biofilm control), “fluorides,” and also the “visits to the dentist” (including the application of fissure sealants).

16.2.1

Nutrition

Doubtlessly, short-chain carbohydrates, also named sugars, are one promoter of the development of caries, since no caries occurs if the bacteria in the dental plaque or biofilm have no access to metabolizable carbohydrates. After a sugar intake of even small amounts (15 mg sucrose), relevant acid production by the bacteria in the biofilm can be measured; after an intake of 500 mg sucrose, the maximum of acid production is reached. Up to now, there is no diet completely inhibiting caries. However, it is meaningful to reduce the daily intake to a minimum, since by this measure the development can be reduced. Therefore, nutrition advices or recommendations should be given as early as possible (in kindergartens, schools) but should also be given on a regular basis during the whole lifetime by parents, dentists, and teachers and also in the later stage of life by nursing staff in care homes. Even if we have a decline in caries in most industrialized countries, world consumption of sugars is still quite high and ranges in these countries between 12.5 kg/capita and year (China) and 71.8 kg/capita and year (Cuba) with a mean of 39.9 kg/capita and year [11]. That there is a decline in caries despite the high consumption of sugars depends most likely on the regular use of fluoride products and oral hygiene measures (see below). The WHO recommends

633 Preventive Measures and Minimally Invasive Restorative Procedures

reducing the sugar consumption to a maximum of 10% of the total calorie intake; if the effect of sugar consumption on caries development is considered, the WHO recommends even a maximum of 5%. Sugar includes all free mono- and disaccharides artificially added to and naturally contained in food and beverages, including juices, honey, and syrup. This means that in case of a 2000 kcal intake per day, a maximum of 10 kg/capita and year should be consumed [12]. Even the lowest consumer in the list mentioned above consumes more than allowed according to the WHO recommendations. However, not only the absolute amount of sugar is relevant. The frequency of intake might be more important, since it has been shown that with an increase of absolute amount and intake frequency, the caries increment increases more than with the increase of absolute amount alone without increase of intake frequency [13]. This depends most likely on the asymptotic pattern of acid production after different amounts of sugar consumption. >> The frequency of sugar intake might be more important than the absolute amount of sugar consuption alone for the caries disease.

It is not clear which type of food is of particular cariogenicity. The content of free sugars (mono- and disaccharides) is of predominant relevance. However, also processed starch can be metabolized by the plaque bacteria. The combination between sugars and processed starch is highly cariogenic. Furthermore, several other chemical and physical factors contribute to or reduce the cariogenicity such as an increase in saliva flow, stickiness, consistency, protein, or fat content. Individual factors like the respond of the salivary gland on stimulating impacts, tooth position, and bacterial composition are also relevant. Saliva flow and tooth position determine the oral clearance rate, the time between food intake, and its elimination from the mouth. With regard to caries, a tooth-friendly nutrition should therefore contain low amounts of free sugars, should not be sticky, and should have a consistency requiring chewing, which leads to an increase of saliva flow. The frequency of consumption at main meal or snack should be reduced to a minimum, in order to give the saliva the chance to remineralize initial carious lesions [13]. As snack milk products, fruits and vegetables can be recommended. However, one has to bear in mind that teeth can be damaged by other components than sugar in the foodstuff, such as acids, which can induce erosive tooth wear [14]. Nutrition advices should be given to everybody in terms of primary prevention. In particular, if the caries risk is high, nutrition recommendations should be an integral part of the whole concept. Nutritional habits can best be recorded with a nutrition protocol. Relevant food and beverages can easily be identified, and alternatives can be recommended. In particular in the case of young children, nutrition advices are of major importance in order to avoid the development of early childhood caries. In this context also the effect of acidic food and drinks should be pointed out.

Tip

Nutritional habits can best be recorded with a nutrition protocol. Relevant food and beverages can easily be identified, and alternatives can be recommended.

The cariogenicity of food and beverages can be assessed by standardized test procedures. One is the intraoral plaque pH measurement; the other is the assessment of degree of demineralization of enamel samples in the oral cavity. It is measured in the plaque how deep the pH declines after a sucrose consumption and whether the critical pH for caries is reached. A foodstuff or beverage is defined as “tooth-friendly” if the plaque pH does not sink below 5.7 within 30 min after consumption [15]. There are alternatives to sugars, which have a sweet taste but no cariogenicity. One can distinguish between caloric and non-caloric sweeteners as well as between those having volume and being a substitute for sugar and those with a very high sweetening power and without volume, which can only be used as an additive to but not as a replacement for sugar. The caloric ones are mainly the sugar alcohols mannitol, sorbitol, and xylitol. Both sorbitol and xylitol are part of plants, from which xylitol is extracted; sorbitol is mostly produced industrially by hydrogenation of glucose. Sorbitol can be metabolized by Strep. mutans, however, only to a small extend, and the pH decline is mild and ends at values higher than the critical pH [16]. Therefore, sorbitol is classified as non-cariogenic. There are several studies dealing with xylitol, all showing a caries-reducing effect of this sugar alcohol [17–19]. Xylitol is not metabolized in the bacteria; rather the molecule is transported inwards and later outwards the bacteria under loss of energy [16]. Several other aspects are discussed to play a role such as the reduction of Strep. mutans in the saliva or reduction of virulence of Strep. mutans, both playing a role in the reduction of cariogenicity in the oral cavity [20]. Xylitol was at the beginning only used in chewing gums and some oral hygiene products. Nowadays, a lot of xylitol containing snacks, sweets, chocolate, and other foodstuff are available, as it has been shown that xylitol is not only non-cariogenic but also a good option for patients suffering from diabetes mellitus. A side effect of sugar alcohols is that they can lead to diarrhea due to slow resorption in the bowel; however, in most cases this effect is only temporarily. Non-­caloric sweeteners include cyclamate, aspartame, and erythritol. The first two molecules have a very high sweetening power. It is often discussed whether they have a health-­harming effect, and some countries have already forbidden the use in particular of cyclamate. Erythritol is a non-caloric sugar alcohol with nearly the same volume as sugars but with a slightly less sweetening power. It can therefore, at least in part, be used as a substitute. First studies show that also erythritol has a beneficial effect on oral health, maybe comparable to xylitol [21]. As mentioned for other sugar alcohols, it can induce diarrhea; in addition it can provoke during consumption a cooling effect on the oral mucosa and the tongue, which is not accepted by all persons.

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>> Sugar alcohols, such as xylitol, erythritol, and sorbitol, are good alternatives to sugars, as they have a comparable sweetening power, are voluminous, and have a comparable taste but are not cariogenic.

16.2.2

Oral Hygiene

Oral hygiene is one of the key components of prevention. The goal of oral hygiene measures is on the one hand the mechanical removal of the plaque from the tooth surfaces and, on the other hand, the administration of active agents such as fluorides but also compounds for chemical plaque removal or modification in order to maintain oral health. Plaque removal is of major importance to avoid both caries and also periodontal disease. In this chapter only the relevance of plaque removal in the context of caries should be discussed. As plaque is one of the key components in the development of caries, the regular and sufficient removal of the bacterial biofilm is not only meaningful but also biologically plausible. For most people oral hygiene is well integrated into the daily routine and a basic element of the personal hygiene and oral health maintenance. Different aspects in oral hygiene contribute to success of the efforts, i.e., duration, frequency, technique, systematics, and oral hygiene aids. 16.2.2.1  Duration and Frequency

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While in the middle of the last century the mean brushing duration ranged between 30 and 60 s [22–24], nowadays the duration in most industrialized countries lays at 2–3 min [25, 26]. These changes to durations, which have been proven to be most effective, are a result of structured preventive programs and can be rated as one of the successes of such concepts. The recommendation to brush 2–3 min bases on the findings that the efficacy of brushing can be enhanced by approximately 55% by prolonging the brushing duration from 30 s to 180 s; as from a duration of 150 s, a maximum of enhancement is achieved [27]. It takes 24–36 h until a matured plaque has established on the tooth surfaces. Therefore, biologically seen, it would be enough to clean once per day the teeth to maintain their health. However, most people are not able to remove plaque sufficiently from all surfaces. Therefore, it is generally recommended to brush the teeth two times per day. This recommendation is supported by different studies. They have shown that with a frequency of two times per day, the risk for an increase of caries incidence and increment is lower than for a frequency smaller than two times per day; a frequency higher than two times per day has only limited additional benefit [28]. >> Brushing teeth two times per day for two minutes each is effective for preventive caries. This measure is biologically plausible and he recommendation is supported by various studies. 

16.2.2.2  Technique and Systematics

Several techniques have been developed for sufficient cleaning of teeth under various conditions. While during childhood easy motions are recommended such as circling on the smooth surfaces and scrubbing on the occlusal surfaces (Fones technique) [29], more complex techniques are recommended, which require more dexterity, as soon as the patients are able to perform these (usually if the patients reached the school age). The most recommended technique is the modified Bass technique (MBT), where the toothbrush bristles have to be positioned at the gingival margin in a 45° angulation with the direction of the bristles towards the sulcus. The brush has to be moved with small jiggling motions and wiped out towards the occlusal area including a rotating movement. With these motions the plaque will be loosened at the margin and removed with the wiping [30, 31]. The MBT can be used if the periodontal structures are healthy as well as if the periodontium shows some preexisting damage. It is mostly recommended in case of intact interdental papillae and if the gingival margin ends up at the cementoenamel border. For the Charters technique, the bristles of the brush again have to be positioned at a 45° angulation, however, this time with the bristles directed towards the occlusal surface. Small circling movements have to be done, and the bristles should be pushed with small movements into the interdental space. This technique is recommended to patients with residual pockets after periodontal therapy and with free interdental spaces. The Stillman technique has been developed for patients with healthy periodontal tissue but showing recessions. The bristles of a soft toothbrush have to be positioned on the gingiva and wiped out towards the occlusal surface with a rotating movement (white to red technique). Even if the MBT is named as the most recommended technique, only a few persons use this complex technique [26]. In addition, studies have shown that it is not better than the others with respect to plaque removal; rather, it has been shown that none of the mentioned techniques is superior to another [32, 33]. Therefore, it seems of secondary importance which technique is recommended, provided that the oral hard and soft tissues are not damaged during the brushing process. More important than the technique seems to be that patients perform a systematics in order to sufficiently reach all areas. An equal brushing of all areas most likely leads to a better plaque removal, independent of the order of brushing. A sufficient systematics should be taught as early as possible [34, 35]. >> It seems of secondary importance which brushing technique is recommended to the patient. More important than the technique seems to be that patients perform a systematics in order to sufficiently reach all areas.

635 Preventive Measures and Minimally Invasive Restorative Procedures

16.2.2.3  Oral Hygiene Aids

The most commonly used tool for cleaning teeth is the toothbrush, either a manual one or a powered one. The manual toothbrush is currently the most used form of toothbrush, since it is cheap, easy to acquire, and usable independent of electricity. The manual toothbrush should have a short head (max. 2.5 cm), equipped with rounded, elastic plastic bristles, which are arranged in tufts (multi-tufted, 20–40 bristles in each tuft), and should have a length of 10–12  mm and a thickness of 0.18–0.25  mm [36]. Too hard or not rounded bristles can lead to violation of the soft tissues. There are brushes with different head designs available; however, studies have shown that the acceptance of the brush itself by the patient has more impact on the cleaning efficacy  than the brush head design. The force used should not exceed 200 g (appr. 2 N) in order to avoid any damage of soft and hard tissues [37]. The brush should be changed after 4–6 weeks or in case of bending of bristles. In order to avoid unnecessary accumulation of bacteria, the toothbrush should be allowed to dry in the air. If more than one brush is used in parallel, the bristles can completely dry within 24 h. The complete drying can on the one hand reduce numbers of germs on the tooth brush head and can in addition  increase  the toothbrush’ longevity. After each infection in the mouth-throat region brushes should also be changed to avoid any reinfection. Tip

There are brushes with different head designs available; however, studies have shown that the acceptance of the brush itself by the patient is more important for cleaning efficacy than the brush head design.

Powered toothbrushes can be divided into rotating-­oscillating brushes, wiping brushes, sonic brushes (amplitudes: ca. 250– 350 Hz), and ultrasonic brushes (amplitudes: ca. 1.5 MHz). In principle, powered toothbrushes are highly effective and could potentially be more effective than manual ones. However, systematic reviews have shown that electric toothbrushes, at least the rotating-oscillating brushes, are only marginally superior to the manual ones [38]. For the others there are not enough studies available to give final conclusions. That not a clear superiority of powered toothbrushes was found might be due to lack of good designed studies, the lack of use of a sufficient systematics [39], or the decrease of “the charm of the new” in case of an electric device after a short period. Due to the smaller brush head in case of an oscillating-rotating model, the patients have to pay attention on very systematic handling. Mostly, patients need more time with the electric device than with the manual brush. Studies have in addition shown that the force used with electric brushes is mostly lower than with the manual ones [40]; this might be an option for patients using habitually high brushing forces. (Ultra)sonic brushes are particularly technique sensitive. They should not be used with the same contact

pressure as rotating-oscillating brushes or manual brushes and with different movements. These brushes work via the formation of micro-flow and hydrodynamic effects in the plaque and not by the direct removal of the plaque by the movement of the bristles [41]. The brushes have to be placed, like it was described for the modified Bass technique, in a 45° angle on the gingival margin with the bristles directing apically, however without any pressure. The brush has to be held there for some seconds, and, optimally, afterwards the brush has to be wiped out towards the occlusal surface. Using this brush with normal or high pressure leads to a reduction of efficacy. Patients have to be sufficiently taught in this special technique; used without the correct technique but with movements recommended for manual toothbrushes, the benefits of the sonic technology will not be exhausted, and the brush acts more or less like a normal manual toothbrush. >> Powered toothbrushes are only slightly superior compared to manual toothbrushes regarding plaque removal. Sonic brushes seem to be particularly technique sensitive.

Common to all toothbrushes is that they cannot directly reach the interdental spaces, even if there are some in vitro studies showing some effect of the sonic brushes on plaque in artificial interdental spaces [42]; the final evidence, however, is lacking. Therefore, additional aids are necessary to clean these areas, which in sum account for 30% of the whole surfaces of the teeth. Interdental cleaning aids are dental floss (waxed, unwaxed, tape, super floss, or devices with fixed dental floss), medical toothpicks or interdental sticks, interdental brushes (with metal core or metal free), and powered devices including high-velocity microdroplet devices. If dental floss is used, a piece of at least 50–70 cm will be taken and winded around the middle fingers. With the thumb and index finger, the floss will be tensioned and with small sawing movements inserted into the proximal space. Here, the floss will be moved up and down while cleaning both surfaces of the adjacent teeth. If dental bridges or blocked crowns are present, special dental floss with a stiffened end for precise insertion of the floss under the pontic is available. This floss has a fluffy part, with which the pontic can be cleaned from below. Waxed floss can be inserted easier into the interdental space, whereas unwaxed floss has a higher cleaning potential. If the interdental spaces and the contact points are very narrow, Teflon tape can be used. Even if the evidence for use of dental floss is low [43], the use of it is biologically plausible. It has been shown that the professional use of floss can lead to a significant reduction of caries increment compared to use of floss at home, where sufficient use was not guaranteed [44]. An alternative to the use of dental floss is the use of interdental brushes, which seem to be slightly superior to dental floss [43, 45, 46]. In addition, interdental brushes are often more accepted by patients due to higher comfort; however, the brushes have to be chosen according to the size of the interdental spaces. In worst case different sizes have to be used, and the patient has to identify which size fits into which space. A further

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increase in ­comfort with a similar cleaning power can be achieved if metal-­free interdental brushes, fabricated from plastic or silicone, are recommended [47]. These products do not provoke any gingiva abrasion [48]; in addition they are very small in diameter and therefore even usable at younger age with healthy periodontal conditions. Due to its conical form, they cover different sizes and reduce the individual fitting to each interdental space to a minimum. The evidence on microdroplet devices is very low. There are only few independent studies on them. It seems to be that at least under short-term conditions, these devices have an efficacy comparable to sufficiently used floss but are more comfortable in use [49]. Conclusively, the evidence for using interdental cleaning devices with respect to reduction of caries increment is low; however, their use is biologically plausible and should therefore be recommended. >> The evidence for using interdental cleaning devices is low; however, their use is biologically plausible and should therefore be recommended.

16.2.3

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Fluorides

Fluoride application in caries prevention is a central measure. It has worldwide been extensively investigated, and there is a bulk of literature and knowledge on this issue. Not only its efficacy but also its toxicology was subject matter of numerous studies. Already in the beginning of the twentieth century, it has been recognized that children in areas with high amount of fluoride in the drinking water (0.7–1 ppm) had less caries; concomitantly, they very often show non-cariously caused enamel spots (mottled teeth) [50]. Highest reductions were found for smooth surfaces followed by proximal areas; in the fissures on the occlusal surfaces, the effect was notably lower. It was hypothesized that a fluoride content in drinking water of approximately 1 ppm has a caries-protective effect. Several other epidemiologic studies have been found in the following comparable effects of fluoride in the drinking water [51]. Two modes of actions of fluoride might be relevant. The ion could either work systemically via incorporation of the fluoride into the developing dental hard tissue (systemic fluoridation) or locally by the contact between the fluoride ion and the erupted teeth in the oral cavity (local fluoridation). Basing on the early observations from the areas with fluoride in the drinking water, it has been assumed over a long period that the systemic fluoridation plays the major role in the caries-preventive effect of fluoride. However, it has been turned out that not the systemic effect is of relevance but the local effects of the fluorides [52]. There are no indications that the preeruptively fluoridated teeth have a lower acid solubility than not preeruptively fluoridated teeth [53, 54]. Consequently, the preeruptive retention of fluoride does not

ensure that the teeth do not develop caries: persons moving away from an area with high amounts of fluoride in the drinking water are at the same risk to develop caries in the area without fluoride in the drinking water as persons never lived in fluoride-rich areas [55]. Different studies have clearly shown that an impact of a systemic fluoridation with fluoride tablets during infancy and early childhood on caries increment in permanent teeth cannot be verified [56]. The same applies for a fluoride supplementation during pregnancy [57, 58]. In fact, all systemically given fluorides in the form of drinking water, fluoride tablets, or fluoridated table salt work predominantly over the local effect during the oral ingestion of the preparation. Therefore, the administration of fluoride tablets should be accompanied by the clear instruction that the tablets have to be sucked and not to be swallowed to take advantage of the local effect. In particular those children having no access to other fluoride sources could profit from this measure; however, the overall balance of fluoride intake has to be considered. In case of regular use of fluoridated salt or fluoridated mineral or drinking water, no tablets should be used. As regularities clearly differ between various countries, no explicit dosage of fluoride supplementation or application should be given here; in this context, reference is made to the local regulations. As it has been shown that the local fluoridation is of major efficacy, most countries nowadays prefer the local application of fluorides. Such approaches include the regular home use of toothpastes, mouth rinses, and gels or the professional application of highly concentrated preparations such as varnishes or fluids. Already in the late 1890s, first fluoride-containing oral hygiene products (rinses, toothpaste, and tooth powder) were fabricated. Mostly, hardly soluble calcium fluoride was added, making the efficacy of the compounds questionable. In the early 1960s first toothpastes with stannous fluoride or amine fluoride were marketed and comprehensively promoted. However, only in the 1990s, it has been shown that the comprehensive usage of fluoridated toothpastes but also of other fluoride sources was associated with a decline in caries prevalence [59, 60]. Later on, several systematic reviews have shown that the regular local use of fluorides is notably effective in reducing caries [9, 10, 61–65]. >> Fluorides can work systemically and locally. The systemic effects of fluorides are very low. The major share of fluoride effect in caries prevention depends on the local effect of the ion after topical application.

16.2.3.1  Conventional Fluorides and Effect

of Fluoride Ions

Several fluoride compounds are used for prevention of caries. These compounds can be divided into inorganic and organic fluorides; the inorganic ones can be subdivided into those having a monovalent ion as a counterion to the fluoride ion (conventional fluorides) and those having a polyvalent metal cation as a counterion (7 see 16.2.3.2). The conventional  

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­ uorides include sodium fluoride (NaF), sodium monofluofl rophosphate (NaMFP), and amine fluoride (AmF, such as dectaflur and olaflur or amine fluoride 297). While the fluorides AmF and NaF can be easily split in aqueous solutions into the ions, an intraoral enzymatic or acid-driven hydrolysis process is necessary to split the fluoride ion from the NaMFP. Four reactions between the dental hard tissue and the fluoride can be distinguished. (1) The enamel is slightly dissolved at the surface and forms during reprecipitation CaF2-­ like precipitates. (2) The enamel is slightly dissolved and forms during reprecipitation fluoridated hydroxyapatite or fluorapatite. (3) The fluoride diffuses into the enamel and specifically adsorbs to free binding places at the crystals such as OH−, Ca2+, or phosphate compounds. (4) The fluoride diffuses into the enamel and binds unspecifically in the aqueous coverage of the enamel crystals. In particular the first mentioned mode of action, the formation of calcium fluoride (CaF2)-like precipitates on the tooth surfaces, is of major importance. The CaF2-like precipitates are stabilized intraorally on the tooth surfaces by phosphate groups and saliva proteins. In case of a plaque accumulation and bacteria-induced pH decline in the biofilm, parts of the CaF2-like precipitate are dissolved releasing fluoride ions. This fluoride can diffuse into the enamel, and the modes of action 2, 3, and 4 could take place. A sufficient plaque removal with fluoridated toothpaste recovers the CaF2-like precipitate, which again forms a reservoir for fluoride ions. The CaF2-like layer is insofar of major importance as it can protect the underlying enamel against acid impacts. If this layer is incomplete, the underlying enamel can be dissolved, even if fluoride has been incorporated into the crystals. However, the critical pH of fluoridated enamel is decreased, which can lead to a lower solubility of the enamel itself [66]. The amount of CaF2 formed on the tooth surface depends on the concentration of fluoride in the preparation (the higher the more), the application duration (the longer the more), the pH of the preparation (the lower the more), and the fluoride compound [67]. It has been shown that AmF leads to a higher CaF2 formation than NaF as well as the fluorides containing polyvalent metal cations [67, 68]. All fluoride preparations lead to an enrichment of fluoride in the upper structures of enamel [69]; the penetration depth is limited and depends also on the compound used. While readily dissociating fluorides easily diffuse into the upper enamel structures, this process takes much more time in case of NaMFP, since this compound has to be split enzymatically [70], with the consequence that after NaMFP application, the fluoride uptake is lower than after the other compounds [70, 71]. In case of healthy enamel, there is a chemical balance between the saliva and the dental hard tissue, leading also to a delivery of fluoride into the environment. In case of a carious demineralization and a fluoride application, however, the fluoride uptake is much higher, leading to a permanent enrichment with fluoride ions.

>> The formation of CaF2-like layers on the tooth surface is of major importance for caries prevention as it constitutes a fluoride reservoir from which fluoride can be released during a cariogenic acid attack. The amount of CaF2 formed on the tooth surface depends on the concentration of fluoride in the preparation, the application duration, the pH of the preparation, and the type of fluoride compound.

Fluoride is also retained in the dental plaque in form of ionized, ionizable (weakly bound), and bound fluoride. The bound fluoride is connected to organic components in the plaque and to the bacteria. The weakly bound fluoride is the abovementioned phosphate-stabilized fluoride. At neutral pH, only low amounts are present as ionized fluoride; in case of pH decline, bound fluoride will be set free, both from plaque, CaF2-like precipitates, and dental hard tissue, and the absolute amount of ionized fluoride increases [72]. The basic principles of anticariogenic effect of fluorides are (1) reduction of acid solubility of the dental hard tissue and (2) inhibition of demineralization as well as promotion of remineralization. The hydroxyapatite in the dental hard tissue is not the stoichiometric form of this compound but a deficient one. Several crystals show deficits and imperfections. In these areas, fluoride can be incorporated during maturation of the teeth, in both preeruptive and Posteruptive enamel maturation. By the filling of the deficiencies with fluoride, the crystalline structure is stabilized which modifies or reduces the solubility of hydroxyapatite. Fluoride ions, however, do not only fill the deficiencies but also replaces the hydroxyl ions (conversion of hydroxyapatite into fluorapatite). This leads also to a reduced acid solubility. The replacement is limited: during preeruptive formation of hydroxyapatite, approximately 10% can be replaced. Posteruptively, the surface can also be enriched with fluoride ions by a topical application of fluoride preparations. Comparable, the interaction between the fluoride ion and the surface causes also a substitution of hydroxyl with fluoride ions. However, the depth penetration is limited. The caries inhibition can only be partly be explained by the mentioned effect on solubility. An equally important mode of action is the impact of fluorides on de- and remineralization. The enrichment of the tooth surface by the topical application of fluorides with weakly bound fluoride (CaF2-­like precipitates) allows that during a carious pH decline, fluoride can be released into the aqueous phase. These free fluoride ions can protect the crystals of the dental hard tissue by forming fluorapatite and by reducing their solubility. During the neutralization process, the fluoride ions precipitate together with calcium ions and dissolved hydroxyapatite, forming fluorapatite and fluoridated apatite. These fluoride-­enriched minerals precipitate earlier, as the solubility product of hydroxyapatite and fluorapatite differs. Therefore it can be concluded that the demineralization is reduced by the inclusion of the fluoride but also the remineralization due to the earlier precipitation [72–74]. This chemical and dynamic balance prevents, if a good oral

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hygiene and less sugar ­consumption are present, a dissolution and destruction of the teeth. However, in case of very aggressive cariogenic demineralization, a net loss of mineral can occur resulting in the formation of white spot lesions. For the process of enrichment of the dental hard tissue with fluoride ions, concentrations of 0.1 ppm fluoride in saliva are necessary, which can be achieved by the regular application of topical fluorides. >> The basic principles of the anticariogenic effect of fluorides are the reduction of acid solubility of the dental hard tissue and the inhibition of demineralization in combination with the promotion of remineralization.

16

In addition to the effect on the tooth structure, fluoride has also an effect on the bacteria in the dental biofilm. With increasing fluoride concentration, first the metabolism of bacteria is influenced, then the bacterial growth is inhibited, and finally a bactericide effect can be reached, however, not by the concentrations found in the dental plaque. The pH in the dental plaque substantially influences the antibacterial effect of fluoride; with decreasing pH values, distinctly lower concentrations for inhibition of bacterial metabolism are necessary. However, the more acid tolerant a bacterium is, the higher is its fluoride tolerance. But luckily, in particular those bacteria metabolizing glucose could be influenced by fluoride. The fluoride can inhibit after uptake into the germ an enzyme in the glycolysis, i.e., the enolase, responsible for formation of phosphoenolpyruvate, an intermediate product in the way from glucose to lactate [75]. In addition, the glucose uptake can also be inhibited by fluoride. Two ways are possible: (1) The phosphoenolpyruvate phosphotransferase system – which is responsible for the conversion of glucose to glucose-6-phosphate, the form necessary for uptake into the bacteria – can indirectly be inhibited by the inhibition of the enolase and the lack of phosphoenolpyruvate. (2) In case of low pH in the plaque and at high concentrations of substrate, the glucose can directly be taken up into the bacteria without any transport systems driven by the pH-dependent proton gradient between the outer and the inner part of the bacterium. In case of presence of fluoride, a part of the protons will be absorbed by the fluoride, leading to hydrofluoric acid (HF), which can be directly transported into the bacteria. In the bacterium the HF dissociates intracellularly and sets H+ ions free, which reduces the proton gradient and follows the driving force of the glucose uptake. In parallel the dissociation of HF in the bacterium decreases the intracellular pH, which in turn destroys the pH optimum of the enzymes of the glycolysis [76]. Both the reduction of glucose uptake and the reduction of enzyme activity inhibit the bacterial metabolism. Furthermore, the formation of intracellular storage carbohydrates is inhibited, as well as the synthesis of lipoteichoic acid, necessary for bacterial adherence. No impact on the degradation of intracellular storage carbohydrates as well as on synthesis of extracellular storage carbohydrates was found [73].

Over time the oral microorganisms can adapt to the fluorides (development of a type of resistance), in particular, if high fluoride concentrations are used. However, the capacity of the germs to metabolize sugars is reduced – the pH decline is milder and shorter. The benefit of a milder pH decline is that the ecological shift to more acid-tolerant and acid-­ producing bacteria is less pronounced [75]. >> Fluoride ions have an impact on cariogenic bacteria. They can reduce the bacterial metabolism by inhibiting the uptake of glucose into the bacteria, by inhibiting of enzymes of the glycolysis, and by inhibiting the synthesis of lipoteichoic acid, necessary for bacterial adherence.

16.2.3.2  Fluorides with Polyvalent Metal

Cations

Besides the “conventional” fluorides, also fluoride compounds containing polyvalent metal cations are available, such as stannous, titanium, and silver ions or zinc and copper ions. Titanium tetrafluoride is not approved for use in oral hygiene products and should not be described here in detail. The other ions have already been used at the end of the nineteenth and the beginning of the twentieth century in dentistry as an antibacterial agent. Copper and zinc are able to increase the intra-bacterial production of peroxides and superoxides, inducing a damage of bacterial DNA and the inhibition of growth-relevant enzymes [77]. Furthermore, all mentioned polyvalent metal cations can react with sulfur compounds, such as thiols and proteins, disturbing the protein function and the metabolism of the bacteria. Stannous ions are able to inhibit in addition to the enolase two further enzymes of the glycolysis, the aldolase and the P-glycerin-aldehyde dehydrogenase, resulting in a lower pH decline in case of sugar intake [78–80]. It is speculated that the polyvalent metal ions also react with the lipids of the bacterial cell membrane provoking an impairment of the membrane function up to a disintegration of the whole membrane structure [81]. Often stannous ions are used in combination with amine fluoride, which can easily penetrate the bacterial membrane [82]; both compounds can reinforce each other in effect. No development of resistance of the bacteria against the polyvalent metal cations was found, which is of major importance in the context of the discussion about development of resistances due to antibiotics. In addition, the toxicological potential of these ions is very low [83]. Side effects could be a dull feeling on mucosa and dental hard tissue as well as removable staining of the dental hard tissue. The metal cations have a high substantivity and are retained in the oral cavity over a long period. In addition to the effects on the bacterial metabolism, the metal cations, at least stannous ions, can be incorporated under acidic conditions into the upper structures of the dental hard tissue, leading to a reduced acid solubility of the dental hard tissue [84, 85]. The application of stannous in

639 Preventive Measures and Minimally Invasive Restorative Procedures

combination with ­fluoride [68] as well as of silver ions in the form of silver diamine fluoride leads to a higher formation of CaF2-like precipitates on the tooth surfaces, potentially promoting the anticariogenic effect. However, the additional effect of polyvalent metal cations to fluoride on reduction of caries increment is negligible in case of a normal caries risk. If special care, however, is necessary (manual or mental disabilities, dry mouth, root caries, early childhood caries), the application of these fluoride compounds appears meaningful. In particular silver diamine fluoride and stannous in combination with fluoride could be a good option [86–90]. >> Fluoride compounds containing polyvalent metal cations, especially stannous and silver ions, could be a good option in particular if the caries risk is high. The cations lead to higher retention of CaF2-like material on the surface, a change of acid solubility of the dental hard tissue (stannous ions), and a more pronounce impact on bacterial metabolism than the fluoride ions alone.

16.2.3.3  Efficacy of Fluoridated Preparations

and Toxicology

As mentioned above, several systematic reviews show that fluoride is of notable efficacy in preventing caries [9, 10, 61– 65]. The effect of preeruptive fluoridation by systemic administration of fluorides is considered to be small; the topical effect of both highly and lowly concentrated fluoride mainly contributes to the anticariogenic effect [91]. The effect of fluorides is highest on smooth free surfaces than on proximal surfaces and lowest on occlusal surfaces (in pit and fissures). Here other preventive measures, in particular in case of high caries risk, are more meaningful, such as pit and fissure sealing (see below). >> The effect of fluorides is highest on smooth free surfaces than on proximal surfaces and lowest on occlusal surfaces (in pit and fissures).

The efficacy of fluorides depends on the concentration and on the form of delivery as well as on the lifetime duration of fluoridation and on individual caries risk. Systemic fluoridation can achieve a caries-reducing efficacy. However, one has to bear in mind that these measures mainly work via the direct topical contact between the fluoride ion and the dental hard tissue. Drinking water fluoridation and salt fluoridation is comparably effective with caries reduction in the range of 50–60%. The results for fluoride tablets are less homogenous; they have an effect in the range of 28–61% of caries reduction. Toothpaste plays the major role in fluoride delivery. It has been shown that toothpastes, with a fluoride content in the range between 1000 ppm and 2800 ppm, show an increase in efficacy with an increase in concentration with a more or less linear dose-response relationship. However, in most countries, toothpastes with a concentration higher than 1500 ppm

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(in some countries even higher than 1000 ppm fluoride) are not available as an over-the-counter product (for details please take the local regularities into account). Toothpastes show in various studies quite different efficacies, in particular if used as a conventional fluoride preparation for daily oral hygiene under unsupervised conditions. The caries-­ inhibiting effect most likely does not exceed 20%. In some countries fluoride toothpastes with very high concentrations (5000 ppm) are available but only on prescription for adults. These products are indicated for therapy of root caries in order to prevent the development of new lesions and to reduce the progression of existing lesions. They could also be significant in case of high caries risk (xerostomia, manual disabilities, etc.). Beneficial effects of mouth rinses are mostly masked by the regular use of fluoride toothpastes if the patient has a normal to low caries risk. In case of high caries risk, the benefit of this measure might be found. According to systematic reviews, mouth rinses with a fluoride content between 250 and 500 ppm can achieve 20–45% caries reduction. Fluoride gels and fluids with concentrations up to 1.25% show a very high variation in efficacy (3–48%). This is mainly due to the fact that they are used at home only weekly or even more seldom. The professional tray application two to four times per year shows a more constant efficacy with a caries reduction between 20% and 40%. The effect of varnishes is given with 20–75% caries reduction [9, 10, 61–65]. There is a bulk of knowledge on the toxicology of fluorides from the dental literature but also from research on osteoporosis. The used dosages in dentistry can be all classified as safe, and it is well-known that fluoride in oral hygiene products and prophylaxis products is not toxic for human being if used as intended. For sure, overdosages are possible, if the preparations are misused. One has to distinguish between acute and chronic overdosage. Signs of an acute overdosage are typical signs of poisoning such as nausea, vomiting, and stomachache. Additionally, symptoms like sweating, headache, and increased saliva flow can occur followed by spasms and tetany. Fluoride has direct impact on the calcium-potassium equilibrium. The calcium level will decrease if the potassium level increases. Potassium has a direct impact on heart activity. As a consequence, arrhythmia, low blood pressure, and reduction of breathing frequency including a respiratory acidosis can occur; finally the patient can die. As an antidote emesis should be induced, if there is no aspiration hazard, or calcium-rich preparations (CaCl2, Ca-gluconate or milk) should be given in order to complex the fluoride ions [92]. In addition, the patient should be hospitalized. The acute lethal dose of fluoride ranges between 32 and 64 mg/kg body weight (certainly toxic dose, CTD). This range is determined by the effect that different fluoride compounds, the individual resorption velocity, and the pH of the compounds impact the toxicity. But also below this, threshold poisoning effect can occur, which can be extremely deadly. In particular infants are at risk for probable toxic effects. The probably toxic dose (PTD) is 5  mg fluoride/kg

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body weight. If a child has ingested this amount of fluoride, medical measures should be arranged [93]. This dose can be reached in case of infant with 10 kg body weight by 100 fluoride tablets with 0.5 mg, 50 liters of fluoridated mineral water with 1 ppm, 156 g fluoridated table salt, 100 g (= 67 ml) of a 500 ppm fluoride toothpaste (approximately 1.25 tubes), or 50 g (= 33.5 ml) of a 1000 ppm fluoride toothpaste (approximately 0.5 tubes). Therefore, infants should not have access to fluoride products, and oral hygiene should be performed with supervision [93], preferably after meals as the resorption of fluoride is much higher if the stomach is empty than after a meal. Higher concentrated gels (1.25% fluoride) should be applied in children with individual trays [94]. Highly dosed fluoride preparations should only be applied by professionals. Preparations which prevent any unnecessary swallowing of fluoride should be preferred, for example, varnishes, which harden in case of contact with saliva. If such preparations are used, no toxic relevant increase in  plasma levels in (pre-) school children were found [95]. Chronic fluoride exposure with more than 1.5 mg/day can induce during enamel formation dental fluorosis [96]. In particular, if several fluoride sources are combined, the risk for fluorosis increases, such as tablets, salts, and/or drinking water. >> The used dosages in dentistry can be classified all as safe, and it is well-known that fluoride in oral hygiene products, supplements, and prophylaxis products is not toxic for the human being if used as intended.

binds intraorally to the pellicle as well as to the bacterial cell membrane, and the integrity of which can be disturbed by this compound [101]. The efficacy spectrum of CHX is broad; in particular Strep. mutans reacts very sensitively [102]. CHX can provoke some local side effects such as staining of teeth and restorations, changes in taste, increased formation of tartar, and desquamation of the oral mucosa [103]. CHX has a very good substantivity and is potent in reducing the intraoral plaque level [103]. Due to its potential side effects, it is not intended to use CHX permanently; however, it is suitable in phases of high caries risk, such as during eruption of teeth, when a fissure sealing is not yet possible due to inadequate moisture control and shows efficacy comparable to fluoride varnishes [104]. In these cases varnishes with at least 1% CHX should be used [97]. If there is a high caries activity, a short-term CHX therapy could be applied. During a period of 14 days, 1% CHX gel could be applied with a tray to decrease the absolute number of bacteria [102]. In two clinical studies, the caries-reducing effect of CHX application has been shown [105, 106]. There is some evidence that the application of CHX varnish during orthodontic treatment around brackets can reduce caries increment [107]. Some other studies give indications that also in case of root caries, a beneficial effect by CHX application can be achieved [108]. However, the evidence for these recommendations is not very high. 16.2.4.3  Probiotics

16.2.4

 dditional Caries Preventive A Strategies

16.2.4.1 Chewing Gums

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Different clinical studies have shown that regular chewing of sugar-free chewing gum can have an impact on oral health [97]. It increases the saliva flow during the chewing process and also the pH of the saliva. In addition, the plaque formation and concentration of mutans streptococci and lactobacilli in saliva can possibly be reduced. Studies on children investigating the effect of supervised chewing of sugar-free chewing gum several times per day have shown that the caries progression and the caries increment can be reduced by this intervention. It seems that chewing gums containing the sugar alcohol xylitol (for mode of action, see [16]) are of particular effectiveness [98]. As there is some evidence on the positive effect of chewing gums, the recommendation of its use up to three to five times per day should be included into the preventive concept. It should be chewed in particular after meals in order to increase the saliva flow and saliva pH to enhance the clearance and the neutralization of acids from the metabolism of plaque bacteria [99]. 16.2.4.2  Chlorhexidine

Chlorhexidine (CHX) is a positively charged molecule, which has at lower concentrations bacteriostatic and at higher concentrations bactericide properties [100]. It

The definition of probiotics is “live microorganisms intended to provide health benefits when consumed” [109]. Such approaches have been used since several decades for the health of the gut. The idea beyond the application of probiotics in the context of caries is to reduce the virulence of the bacterial flora in the oral cavity. It is important that the ingested bacteria have no harmful impact, for example, if they recombine with other bacteria leading to an increase of pathogenicity. The goal is to incorporate probiotics into the biofilm and to replace more pathogenic bacteria by formation of specific cellular mediators, inhibition of bacterial growth, competitive displacement, or modulation of the immune system [110, 111]. The effect depends on what germ is used. Some positive effect has been shown for lactobacillus species (L. rhamnosus, L. reuteri) in the context of root caries. Furthermore L. reuteri seems to have a positive effect on periodontal status. However, even if there are some studies showing a beneficial effect, the evidence is still low. In addition, one has to keep in mind that there is only an effect of the probiotics expectable while they are regularly (preferably daily) ingested. Few days after termination of use, there are no probiotics detectable in the oral cavity [112, 113]. Some cautionary voices argue that by incorporating lactobacilli species into the oral cavity, the number of acid-producing bacteria could potentially be increased with the potential effect of an increase of caries risk. However, there is no evidence for this statement.

641 Preventive Measures and Minimally Invasive Restorative Procedures

16.2.4.4  Ammonia-Forming Agents

f­ragments in combination with phosphate (CPP, patented Urea and arginine can both be metabolized in the oral cavity as Recaldent™) are more effective than the casein itself by specific bacteria, such as S. sanguis or S. mitis. In addition, [121]. In addition it has less allergenic potential [129] and both molecules can be split by enzymes from the saliva, i.e., affects to a lesser extent the taste than casein. The CPP can arginine deiminase or urease. During this biochemical con- stabilize calcium and phosphate in solutions forming amorversion, ammonia is released from the molecules, which has phous calcium phosphate (ACP); both compounds form an alkaline pH [114, 115]. The increase of pH by this process the colloidal complex. The complex is so small that it can leads to a faster neutralization of cariogenic acids, and the diffuse through the enlarged pores of an initial carious pathological shift to a higher occurrence of aciduric and lesion. As ACP is a metastable compound, the CPP acts as acidogenic bacteria can be avoided [116]. According to the a carrier for calcium and phosphate in order to increase the current level of knowledge, both compounds arginine and concentrations of these ions in the carious lesion to promote the remineralization process. urea have no harmful side effects. Several products with CPP-ACP are available, such as There are some oral hygiene products and chewing gums chewing gums, toothpastes, mouth rinses, and prophylaxis containing urea; however, the evidence on their efficacy is pastes, with and without fluoride additives. There are indicalow. Urea-containing chewing gums have no additional effect tions in the literature that it has remineralizing potential; compared to other sugar-free chewing gums [114, 115]. however, the study situation is not fully clear. In particular, Arginine is split by the complex arginine deiminase systhere is no evidence that this compound is better than the tem, which occurs in both the saliva and specific bacteria. standard fluoride. There is also no clear evidence whether the Interestingly, in the biofilm from caries-free surfaces, the combination between fluoride and CPP-ACP shows any benlevel of this enzyme system is higher than in the biofilm from efit in comparison to fluoride alone; however, it shows better carious surfaces. The same applies for the level of ammonia remineralization potential than CPP-ACP alone [130]. The and of the arginine deiminase system in the saliva – caries-­ use of a CPP-ACP in chewing gums seems to have no or only free individuals show higher concentrations than persons little beneficial effect [131]. In case of dental erosion, such suffering from caries. Arginine is used in toothpastes in a preparations fall short of expectation if used as an oral complex with insoluble calcium compounds in order to hygiene product [132]; as an additive to acidic drinks, it can increase the availability of calcium and the remineralization reduce their erosivity [133]. potential. It is used in combination with NaMFP due to the Another calcium phosphate compound is the bioactive calcium-rich formulation in avoidance of reactions between glass, which has been used as remineralizing agent. Even if calcium and fluoride in the preparation. Both modes of there are some in vitro studies showing promising results, the actions – of fluoride and of arginine – are independent, and evidence on the efficacy of such preparations is very small, as both compounds do not inhibit each other. There are some controlled randomized clinical studies are lacking [134]. studies showing a benefit of arginine in stopping caries proOther preparations contain artificial hydroxyapatite, gression and in remineralization of carious lesions [117– which should fill submicron defects with the calcium phos120]. In particular for patients with high caries risk, phate particles in terms of a biomimetic approach. These arginine-­containing products might be of interest. particles can be used at a microscale and at a nanoscale. While minor effect was shown under in vitro conditions for 16.2.4.5  CPP-ACP, Bioactive Glass, the microparticles, the nanoparticles show some effect [135]. Hydroxyapatite The evidence for these compounds for the clinical use is very Casein phosphopeptide-amorphous calcium phosphate low, as comprehensive clinical studies are lacking. In none of (CPP-ACP) is a synthetic colloidal complex derived from the very few studies dealing with this approach, superiority milk. It is well-known that milk can be anticariogenic to the conventional concept using fluorides was found. despite its high content  of sugar [121]. Different mechaConclusively, none of the calcium and phosphate prepanisms might be relevant. Milk is supersaturated with rations without fluoride has been investigated under clinical respect to various calcium phosphate compounds, being conditions in a dimension that allows them to be recompart of the dental hard tissue [122]. Therefore, in the pres- mended as an alternative to fluoride in caries prevention. ence of these compounds, the acid solubility of the dental hard tissue (enamel) is reduced, and remineralization pro- >> None of the calcium and phosphate preparations without fluoride has been investigated under clinical cesses are facilitated [123]. The pH decline after milk conconditions in a dimension that allows them to be sumption is relatively low, which is in addition in parts recommended as an alternative to fluoride in caries buffered by the metabolism of protein compounds to alkaprevention. line end products (e.g., [124]). One of the milk proteins that is of particular importance is the casein [125, 126]. It has been shown that this protein can bind to hydroxyapa- 16.2.4.6  Ozone tite and can influence bacterial adherence and metabolism Ozone is a natural molecule which contains three oxygen [127, 128]. On its own it cannot inhibit completely demin- atoms and has antimicrobial activity against bacteria, fungi, eralization; however, it has been shown that smaller and virus [136]. The ozone therapy on carious lesions

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involves the application of the ozone gas over the tooth’s surface ­aiming its decontamination [137]. The ozone gas can be produced from oxygen in the environment air (lowdosage principle) or from pure oxygen supplied by an oxygen bottle (high-dosage principle). The application of ozone is usually performed through a handpiece, which has a disposable silicone cup tip, with diameter in a dimension (usually 3–10 mm), which can be firmly attached to the selected area of the tooth. It directs the ozone and prevents the escape of the gas into the mouth. After the application, the ozone gas is suctioned off and again converted into oxygen by a neutralizer. The intention of the use of ozone is to arrest caries progression, due to a reduction of the cariogenic bacteria by oxidation processes, aiming to prevent or delay the need for a restoration [138]. However, the ozone therapy did not meet all expectations and can only be classified as an additional option for controlling dental caries. The conventional strategies, such as the dietary advice, oral hygiene instruction, and use of fluorides, are still the primary strategies for caries control [138]. The ozone therapy could potentially be used for disinfection of fissures prior to fissure sealant application or as a noninvasive initial caries lesion treatment. In cavitated lesions it can be used to decontaminate the remaining infected dentin after tooth preparation. The high-dosage ozone application works with pressure. In this case the gas can penetrate into the smallest pit and fissures to reduce or maybe inactivate the bacteria [137]. However, the ozone acts on contact; therefore, any lesions that do not allow the access of the equipment tip or the surface sealing with the silicon tip cannot be treated. These include proximal lesions, hidden caries, or lesions difficult to access. Thus, ozone is mainly used on the occlusal and free-smooth surfaces. There is good in vitro evidence of the prophylactic application of ozone as antimicrobial treatment prior the acid etching and placement of sealants and restorations. Positive results have been obtained without interference on enamel physical properties or adhesive restorative materials [139]. However, there is only limited information from clinical studies, which are in addition in part contradictory. According to manufacturer’s recommendations, the noninvasive treatment of the incipient occlusal caries lesions should be possible. This involves the application of the ozone directly over the lesion for 20–120 s, followed by the application of a remineralizing solution that contains fluoride, calcium, zinc, and phosphate to increase remineralization of the disinfected area. They also recommend the use of a fluoridated toothpaste and mouthwash, as well oral hygiene instructions. The ozone application should be repeated after 3 and 6 months. Even though the first studies have shown some effects on arresting caries and preventive treatment, the use of ozone still requires further studies [140]. Reinfection of the disinfected surface can rapidly occur in the oral cavity if no sufficient sealing of the surface is performed.

16.2.4.7  Further Approaches

For a long time, caries has been classified as an infectious disease. Therefore, it has been considered to develop a vaccine against Strep. mutans. As several bacteria contribute to the development of dental caries, this strategy appears not promising [141]. In addition, the resident flora in the oral cavity is part of the immune system and cannot be eliminated at all. It has also been proposed to avoid any transfer of caries pathogenic germs from caries active parents to the newborn baby; however, this recommendation appears just as little meaningful. More reasonable is an increase of preventive measures and restoration of frank cavities in caries active parents. Such strategies are called primary-primary prevention. Some studies give indications that the chewing of xylitol-­containing chewing gums by the parents during the first time of life of the children can reduce the caries incidence in children, most likely due to the Strep. mutans-­reducing effects mentioned above [142]; however the evidence for this measure is based only on a single study. Another possibility to reduce the biofilm on tooth surfaces could potentially be the photodynamic therapy. This approach is regularly used in dermatology for skin tumor therapy. The intention is to reduce pathogens by application of light in combination with a photosensitizer. This molecule will be incorporated into the bacterial cell membrane and activated by impact of light with a specific wavelength, depending on the sensitizer used. From the molecule oxygen will be split off in the form of radicals, which should destroy the bacterial membrane. This approach is in particular used in areas difficult to reach, such as subgingival regions, what is of interest for periodontal treatments; however, in case of supragingival biofilm in the context of caries, its relevance is questionable. Furthermore, it is not clear how deep the sensitizer can penetrate into a matured biofilm and to what extent the biofilm can be destroyed. In the context of caries, there is no evidence for its efficacy [143]. Some other strategies for caries prevention have been discussed, such as the use of plant extracts, antimicrobial peptides, enzymes, biopolymers, metaphosphates, quaternary ammonium salts, or flavonoids [110, 144]. There is weak to no evidence from clinical studies on anticariogenic efficacy of these compounds, even if a reduction of bacteria can be achieved. However, a reduction of bacteria does not necessarily mean that a compound is caries inhibiting. It has also considered to modify the communication between bacteria in the biofilm (anti-quorum sensing), though without any evidence at this moment. 16.3

Pit and Fissures Sealants

Pits and fissures are more susceptible for development of caries than the other surfaces due to their morphology. The occlusal surface of the posterior teeth presents develop-

643 Preventive Measures and Minimally Invasive Restorative Procedures

a

b

..      Fig. 16.1  a Occlusal surface of molars with biofilm deposits; b mesiodistal cross section of a molar with a sealant applied on the occlusal groove

mental grooves separating the cusp slopes, which is called a fissure. In some areas of the grooves’ bottom, there is no enamel coalescence from one cusp slope to the other, creating a direct path between the oral environment and the dentin [145]. A pit is a located and small coalescence fault on the tooth’s surface. It is generally found on the intersection of two fissures or at the end of a developmental groove. The irregular anatomy of the grooves, pit, and fissures favors food and plaque retention, being an area  at high risk for developing dental caries. Even if the occlusal surfaces constitute only 12.5% of all tooth surfaces, approximately 50% of all caries lesions in school children occur at these surfaces. Regarding the distribution on the posterior teeth, most frequently caries lesion development occurs at the occlusal surfaces of the first and second molars, corresponding to about 90% of all lesions present on children and teenagers (. Fig. 16.1a) [146]. It can be distinguished between different types of fissures: flat and wide, slit-shaped, or ampoule-shaped; in particular the latter two shapes cannot be sufficiently cleaned. As a consequence bacterial biofilm, food leftovers, and cell debris can be retained in these areas. The neutralizing and remineralizing potential of the saliva and also the topical effect of fluoridation measures are also reduced in these areas, resulting in a higher risk for the development of caries. Therefore, materials were developed to be applied into the grooves, closely sealing the pits and fissures, reducing its irregularities, and smoothing the surface. Those materials create a physical barrier between the occlusal surface and oral environment, hampering the deposition of bacteria and its nutrients, as well as the progression of caries lesions (. Fig. 16.1b) [147, 148]. During many years, it was generally accepted that the best way to maintain the molars sound is applying sealants right after the eruption. However, with the reduction of caries prevalence in the industrialized countries, resulting from the progressive increase of the knowledge about the caries dis 

 

ease etiology and prevention, the caries risk assessment has become evident for sealant indication [149]. Many occlusal surfaces remained sound during the entire patient’s life without any sealant. This way, the indiscriminate use of sealants is nothing more than a modern version of the classic concept of “extension for prevention.” This means that sealing all occlusal surfaces to hinder the caries development is considered nowadays as unacceptable and may be considered an overtreatment, since by using other preventive measures caries risk can be decreased and the disease can be controlled [150]. Therefore, monitoring of the etiological determinant factors of caries disease is of major importance, as well as the correct and sufficient preventive use of fluorides. The operatory approach of the occlusal sites varies according to its health and anatomical conditions, as well as the patient’s risk of developing caries lesions. The latter one is the most important factor to be considered when sealants are indicated. Among the clinical parameters that are available to evaluate the caries risk, the previous caries experience seems to be the most accurate criteria [149]. Other factors that indicate caries susceptibility are the retentive macro-morphology of the occlusal surface (. Fig. 16.2a, b), frequent sugar intake, inadequate exposure to fluoride, and poor oral hygiene [151]. In addition, people with hypomineralized teeth, fixed orthodontic appliances, general health problems, manual disabilities, and xerostomia, the use of medication that reduces salivary flow or the frequent intake of medication with high sugar levels is potentially considered a high risk [147, 149]. Based on that, occlusal surface sealing is, in general, indicated for patients at high caries risk and/or presenting teeth with active occlusal incipient lesion, which show progression during the treatment (. Fig. 3.5g, h). In addition, it can be used in patients who are not responding to a treatment based on the control of the disease [149]. It can also be recommended, in case of high caries risk,  to apply fissure sealant on deciduous molars or at the palatal pits of incisors or canines.  

 

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a

b

..      Fig. 16.2  a Posterior teeth with a smooth occlusal morphology and with shallow grooves; b molars presenting irregular morphology, with deep grooves favoring the biofilm deposition

>> The indiscriminate use of sealants is unacceptable and may be considered an overtreatment. Its indication must be done only after the caries risk assessment. It is recommended for patients at high caries risk and/or presenting teeth with active occlusal incipient lesion. Fissure sealing should always be accompanied by other preventive measures, i.e., nutrition recommendations, oral hygiene education, and fluoride application.

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The patient’s caries risk has to be periodically evaluated, since it can change with time. In particular during the period necessary for the eruption of molar teeth (12–18 months), the risk for developing occlusal caries is high due to the lack of chewing friction and natural cleaning mechanisms, as well as due to difficulties to sufficiently reach the occlusal area with mechanical oral hygiene devices. Immediately after eruption the enamel does not have its maximum degree of mineralization. During a period of approximately 2 years after eruption, the enamel undergoes a secondary mineralization process (Post-eruptive enamel maturation), in which minerals, such as calcium, magnesium, and phosphate, from the saliva are incorporated into the dental hard tissue. This complementation of the mineralization is supported by the application of fluorides. These processes result in a reduction of the enamel permeability, which can decrease the caries risk [152, 153]. However, this does not necessarily mean that the matured tooth will be caries-free during the whole life span. All in all, the sealants indication has to be based on the caries risk assessment in different periods of patient’s life, because the tooth can be at low risk immediately after eruption, but due to changes in patient’s behavior or habits at high risk at a later stage of one’s life, and vice versa [146]. To achieve the maximum benefits of the sealants, these materials should be applied only to those teeth judged as high caries risk [146, 154]. Sealants are considered a valuable and low-cost ­preventive measure, and it is an adequate strategy for caries prevention, if correctly indicated and made [155]. However, it has to be ideally used in combination with

patient education, effective personal oral hygiene, rational use of fluorides, and regular dental visits [146]. As fissure sealants are normally applied during age of childhood, the parents have to be informed about necessary preventive measures and the need of regular controls of sealants in the dental practice.

Tip

As fissure sealants are normally applied during age of childhood, the parents have to be informed about necessary preventive measures and the need of regular controls of sealants in the dental practice.

Sealants can also be applied over active incipient lesions on the occlusal surface since it has been shown to be effective in inhibiting the progression of demineralization confined to enamel [156–158]. However, enamel demineralization can be associated with the presence of dentin lesions, in particular if the fissure is very deep and close to the dentin enamel junction. If there is no visible cavitation, such dentin lesions can be sealed. Studies have shown that it can significantly reduce the number of viable bacteria inside the lesion and lead to caries arrestment [159–161]. In fact, there is a trend towards noninvasive approaches, aiming the prevention, arrestment, or management of caries. Following this, sealants can be used both as a preventive measure in at-risk teeth and as a therapeutic measure when applied over an incipient non-­cavitated caries lesion [156, 162]. In case of cavitation, however, an invasive treatment is not avoidable. In such cases a  minimally invasive procedures should be performed in order to avoid any unnecessary substance loss. If one decides in favor of sealing a non-cavitated lesion, the material used for the sealing is of major importance, since a tight closure of all parts of the fissure is a prerequisite. Resin-based material is recommended [163–165]; glass ionomers should not be used as a tight sealing cannot be ensured

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645 Preventive Measures and Minimally Invasive Restorative Procedures

[166]. The sealing of carious deciduous molars is also possible and not worse in comparison to invasive measures [167]. In all cases of sealing carious lesions, a periodic evaluation is essential, both in relation to lesion progression and to sealant integrity and retention. A total or partial loss of the sealant applied over a dentin lesion will open again the entrance for bacteria and for the substrate for the bacteria in the resting carious lesion, favoring the activation of the caries process [154, 168]. One has to keep in mind that sealants placed over dentin lesions, even in combination with adhesive systems, present more micro-leakage and less retention than sealants in sound fissures. Carious fissures are often surrounded by demineralized enamel, which presents reduced adhesive properties adversely affecting the proper adaptation of the sealant in the fissure [169]. Except for a proven allergy, there are no absolute contraindications for a fissure sealant. The presence of a cavitation into dentin, an inadequate moisture control, and deciduous teeth, which will exfoliate soon, can be judged as a relative contraindication. >> Non-cavitated dentin caries lesion can be sealed and arrested. However, periodic evaluation is essential, both in relation to lesion progression and to sealant integrity and retention.

16.3.1

Type of Sealants

Different materials can be used as a sealant. Mostly resin-­ based sealants are recommended, either as unfilled resin formulations or flowable composites. Glass ionomer cements (GIC) are also a possibility; however, this material is in some countries’ guidelines classified as a material to be used only as an interim solution. 16.3.1.1  Resin-Based Sealants

These sealants are based on fluid resins associated or not with filler particles. They contain traditional monomers, such as BisGMA and UDMA, which are diluted with low molecular weight molecules, such as TEGDMA, to obtain a proper viscosity for clinical use. In addition, some products also have white pigments such as titanium dioxide, to differentiate the sealant from enamel, aiming to facilitate the application and its later control during the clinical examination (. Fig. 16.3a, b). Clear sealants, however, allow controlling the underlying fissure system. There is also a sealant available with a thermochromic pigment. This pigment is transparent at the oral temperature, but at temperatures below 31 °C, induced by the use of air or water stream, it becomes bluish, which should facilitate the identification of the sealant in the fissure system (. Fig. 16.3c, d). To facilitate the application of the sealant,  

 

a

b

c

d

..      Fig. 16.3  a, b Sealants with white pigment applied on the molars occlusal surface; c sealants with thermochromic pigment after the polymerization; d bluish aspect of the sealant with a thermochromic pigment after receiving a water spray (Defense Chroma-Angelus)

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companies developed materials which change the color from the non-cured (other color than white or clear) to the cured condition. Resin-based sealants are normally light-curing, but chemically curing materials are also available, both presenting comparable retention rates in long-term evaluations [170, 171]. Some preparations contain fluoride; however, studies have shown that fluoride release by the resin-based sealants is minimal and there is no advantage over the sealants without fluoride. Thus, it seems to be more of a marketing strategy than a real clinical benefit [154, 172, 173]. The addition of filler particles to the sealants aims to improve surface hardness and reduce wear. Although they present improved mechanical properties, they are more viscous, and consequently, the penetration into the etched fissures is more difficult. As the layer thickness is higher after application, they mostly require occlusal adjustment after application [149]. However, there is no evidence for superiority of filled over unfilled sealants in relation to retention rates and caries prevention [147, 174]. Tip

There is no evidence for superiority of filled over unfilled sealants in relation to retention rates and caries prevention. The same holds true for the presence or not of fluoride in the composition and the use of light- or chemical-curing materials.

The outer surface of enamel is prismless (. Fig. 6.1d), which shows smaller porosities after acid etching and impairs the retention of the fissure sealant. Besides, the solubility of prismless enamel is smaller than of prismatic enamel. A minimum etching time of 30 s is required. A reduced etching time leads in most studies to a more heterogeneous retention behavior. It is important to highlight that the acid etching has to reach a larger area than the sealant will cover. The material should never be applied beyond the etched enamel because no bonding would be obtained. After etching and rinsing and drying, the surface should have a chalky/frosty-white appearance as a result of the acidinduced demineralization. The application of self-etching adhesives before sealant application could be used as an alternative to phosphoric acid etching before sealant application; however, the retention rates do not reach those after conventional acid etching [178]. The same applies for laser or air abrasion conditioning [179]. The latter three methods (self-conditioning, laser, air abrasion) cannot be recommended without reservations. To maximize the longevity, the retention, and the durability of the sealants, the application has to follow a standardized protocol: 55 Proper isolation of teeth, preferably with rubber dam (. Fig. 16.4a). 55 Cleaning of tooth surface with pumice and prophylaxis brush or with sodium bicarbonate Prophy-Jet to remove the biofilm and debris from the occlusal surface, that adversely affects the adequate enamel etching (. Fig. 16.4b). The surface can also be cleaned with the patient’s toothbrush without toothpaste [180]. Oily or fluoridated prophylaxis pastes have to be avoided since they may hinder the enamel acid etching. 55 Thoroughly rinsing with air/water spray and drying with airstream. 55 A dental probe should gently be passed through the bottom of the grooves to remove pumice residues and debris. 55 Etching of the surface with 35–37% phosphoric acid gel for at least 30 s (. Fig. 16.4c). 55 Thorough rinsing with air/water spray until complete removal of the acid for at least 20 s (. Fig. 16.4d). 55 Drying of the surface with airstream (. Fig. 16.4e). 55 Applying of the sealant using a dental probe or the applicator tip provided by the manufacturer, directing it towards the center of the pits and grooves and taking care not to incorporate bubbles into the sealant material (. Fig. 16.4f). 55 Note: If it is a self-curing sealant, it is presented in two bottles. One drop of each bottle has to be dispensed, mixed, and applied to tooth surface. The curing time is about 3 min. If it is a light-curing material, the sealant has to be applied directly to the tooth surface and then light-cured for 20–40 s according to manufacturer’s instructions (. Fig. 16.4g). 55 Evaluating of the entire surface of the sealant with a dental probe to ensure its integrity and to verify the  

 

 

16

The sealant application technique, which will be exemplarily presented, does not require the use of an adhesive system after the acid etching step, as it is possible to get similar retention rates with or without an application of a bonding agent, in particular if the moisture management is excellent [175]. Thus, adequate isolation is an essential part of the technique, and the use of rubber dam is strongly recommended. Sometimes it is not possible to use rubber dam, and the cotton rolls isolation has to be performed. Studies have shown than when properly done, results similar to rubber dam can be achieved by cotton rolls isolation. However, if this cannot be ensured, such is the case in partially erupted teeth, glass ionomer cement as sealant should be used instead of resinbased materials (for details see below). Salivary contamination during sealant placement is the most common cause of failure of the technique [154, 176, 177]. Most problems associated with retention loss of a sealant do not occur when it is totally lost. That exposes the fissures system to the oral environment, allowing mechanical removal of the biofilm and contact with saliva and fluoridated oral hygiene products. However, in case of a partial loss and insufficient retention of the remaining sealant, the areas below the partially retained material will hardly come into contact with saliva and fluorides, which can increase the risk for caries development. Furthermore, in particular if dyed sealants are used, the visual diagnosis is impaired [150].

 

 

 

 

 

647 Preventive Measures and Minimally Invasive Restorative Procedures

homogeneity of the material and the absence of bubbles as well as whether the sealant covers the entire extension of pits and fissures (. Fig. 16.4h, i). If necessary, the sealant can be reapplied if no contamination with saliva has happened. If contamination was the case, the acid etching procedure including rinsing and drying has to be repeated before applying additional material.  

55 Removal of rubber dam and evaluation of the occlusion using an occlusion foil. 55 If there is any occlusal interference, the occlusion has to be adjusted using a fine-grain diamond point, a multibladed finishing bur, or an Arkansas stone. 55 If it is recommended in the respective home country, application of a highly concentrated fluoride preparation (varnish or fluid).

a

b

c

d

e

f

..      Fig. 16.4  Light-curing resinous sealant application technique. a Teeth after rubber dam isolation; b prophylaxis with pumice and water; c phosphoric acid etching; d rinsing; e opaque aspect of the etched

enamel; f application of the sealant using the tip of an exploratory probe; g light-curing; h evaluating the sealed surface using the probe tip; i final aspect before evaluating the occlusal contacts

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g

h

i

..      Fig. 16.4 (continued)

16.3.1.2  Flowable Composite Resins

16

Flowable composites, especially those with very low viscosity, can be used as pit and fissure sealants. They present good wetting properties and adequate wear and fracture resistance [145]. Clinically, the results of flowable composites, if used with an adhesive system, are comparable to those obtained with unfilled resin-based sealants [181–184]. The use of an adhesive system after etching is a prerequisite in case of the usage of a flowable composite for occlusal sealing. Except for this additional step, the application technique is similar to the application of resin-based sealants. There is no need to use the primer of the adhesive system, if a three-step adhesive system is used (etching, primer, and adhesive), since only enamel is involved; it is of major importance that in this case the etched enamel is completely dry, to avoid any contact between water and the hydrophobic bonding material. For enamel bonding, the use of etch and rinse systems is always the preferred choice, to achieve a stable and effective bonding [185]. Self-etching adhesive does not lead to a sufficient etching patter, in particular in the prismless enamel, since the pH value of the self-etching primer is higher. As a consequence, its application results in the formation of shorter resin tags compared to the etch and rinse systems. All in all, the self-­etching approach results in lower bonding performance and a poor sealant retention [186, 187]. Thus,

the use of self-­etching adhesive systems is not recommended. After polymerization, the finishing and polishing steps are performed as in case of any regular composite restoration. 16.3.1.3  Glass Ionomer Cement

The use of GIC to seal pit and fissures is a controversial topic in the literature. Some authors believe that they are not adequate for occlusal sealing, because they show high wear and low fracture resistance, as well as poor retention rates [145, 154, 188]. However, other studies showed success rates with regard to occlusal caries prevention similar to the resin-based ones [189]. Two reasons for this effect have been discussed. On the one hand, even when the sealants apparently are lost, residual material remains in the bottom of the fissures and still protects against caries lesions. On the other hand, they can act as a fluoride reservoir, reducing the caries progression [147, 190, 191]. The latter aspect is often subject for a discussion, since it is not clear whether the fluoride effect is measurable in case of the regular use of fluoride containing oral hygiene products. GICs are generally used in terms of a temporary treatment, in particular in situations where sealants are indicated, but adequate isolation cannot be achieved. Typical clinical situations are partially erupted teeth with active white spot lesions and/or patients with high caries risk and

649 Preventive Measures and Minimally Invasive Restorative Procedures

a

b

..      Fig. 16.5  Mandibular second molar erupting into the oral cavity. a Initial clinical situation; b immediately after the application of the GIC as pit and fissure sealant

a

b

c

d

..      Fig. 16.6  Application technique of the GIC used as sealant. a Initial case – maxillary second molar erupting in the mouth of a caries high risk patient; b application of polyacrylic acid after the prophylaxis; c

application of the GIC with the tip of an exploratory probe; d case after 6 months, showing the retention of the GIC on the pit and fissures. The first molar also received the same treatment

previous history of caries lesions (. Fig. 16.5a, b) [152, 192, 193]. Even if they can be used in cases where an adequate isolation cannot be guaranteed, GICs are technique sensitive against desiccation on the one hand and high amounts of saliva in the fissures on the other hand. Moisture control is therefore also for GIC sealants an important factor. Besides conventional GICs, the resin-modified glass iono-

mer cements (RMGIC) can be used. They have to be lightcured but are less sensible to desiccation and water absorption and have better physical properties and retention rates to enamel [152, 194]. The application of the conventional GIC as pit and fissure sealant should be performed according to the following protocol (. Fig. 16.6a–d):

 

 

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55 Cleaning of the tooth surface with pumice and prophylaxis brush or with sodium bicarbonate Prophy-Jet or the patient’s toothbrush without toothpaste. 55 Thoroughly rinsing with air/water spray and drying with airstream. 55 A dental probe should gently be passed through the bottom of the grooves to remove pumice residues and additional debris. 55 Isolation of the teeth using cotton rolls. 55 Application of the polyacrylic acid conditioner to enamel, according to manufacturer’s instructions (. Fig. 16.6b). 55 Note: The surface energy is increased by applying the conditioner, which enhances the wettability and penetration of the GIC into the grooves. 55 Thoroughly rinsing with air/water spray to remove the acid, for at least 20 s, avoiding saliva contamination. 55 Change of cotton rolls. 55 Note: This step is critical because unexpected saliva contamination of the surface will negatively influence the adhesion of the GIC to the tooth. 55 Gentle drying of the tooth surface with airstream. An absolute drying of the tooth surface has to be avoided. 55 Note: The enamel surface will not show the frosty-white appearance observed after the phosphoric acid etching. 55 GIC will be mixed from two components. The mixture should be homogeneous, fluid, and shiny; if manual mixing is performed, the incorporation of air bubbles by strong mixing procedures has to be avoided. Application of the cement using the tip of the dental probe or the application syringe, directing it into the pit and fissures, with care (avoid air bubbles; . Fig. 16.6c). Pressure can be applied with a petroleum jelly-coated index finger to improve the penetration of the material into the pit and fissures [195]. During the initial setting reaction, which takes about 5 min, the surface should not be touched; any saliva contamination has to be avoided. 55 Protect the surface with cavity varnish or bonding agent to avoid syneresis and imbibition processes until the final hardening, which would adversely affect the materials’ physical properties. 55 Checking for bubbles and whether the GIC is correctly applied to all pit and fissures. 55 Removal of the cotton rolls and evaluating of occlusion with articulating paper. 55 If there is excess, manual shaping instruments should be used to remove it. 55 Application of a coating (fluid resin) to protect the surface.  

 

16

If a resin-modified GIC is used, a tooth conditioner or a specific primer has to be applied following the manufacturer’s instructions. Afterwards, the material is placed over the fissures and light-cured. It is usually not necessary to protect the surface of this material, since the resin component avoids

desiccation and water absorption. Finishing and occlusion adjustment steps are similar to the conventional sealant technique presented above. 16.3.2

 ongevity of the Sealants and Effect L on Incidence of Caries

The longevity of the sealants has been proven by clinical studies, which have shown that the retention of the sealant is the most important factor for occlusal caries prevention, since it blocks the bacteria and/or its nutrients [196–198]. The survival rate of the resin-based sealants according to a systematic review study was up to 90% after 1 year, 80–93% after 2 years, 41–87% after 3 years, 70% after 4 years, and 39% after 9 years [199]. A reduction of the sealant retention is observed over the time. Therefore, periodic visits to the dentist are important so that the sealant margins and integrity can be re-evaluated. If there is any fracture or loss (. Fig. 16.7a–d), it should be repaired or replaced if necessary, in particular when the patient still presents high caries risk or when the sealant was applied on teeth with enamel demineralization. Regarding the effect of fissure sealants on caries incidence, it was reported that sealed permanent molars presented up to 73–84% less caries lesions after 2 years compared to the non-sealed molars [199].  

>> A reduction of the sealant retention is observed over time. Therefore, periodic visits to the dentist are important.

16.3.3

 xtended Fissure Sealant E and Conservative Composite Restorations

In 1977, when the extension for prevention principles was still the state of the art for the invasive therapy of dental caries, Simonsen and Stallard wrote the first reports about minimally invasive or conservative preparations. They used No.1/4 round burs to widen those pit and fissures affected by incipient carious lesions (selective enameloplasty of the fissures), which was followed by sealing with self-cure composite dissolved in fluid resin (extended fissure sealant) [200]. Later, the term “preventive resin restorations” was given to small composite restorations, which were made after conservative preparations of small lesions that extend up to the dentin. The preparation was defect oriented, and only the caries-affected area was prepared. The small restoration was associated with a sealant application on the adjacent pit and fissures [201]. Today this kind of procedure is called a “conservative composite restoration” and still includes the same steps: small preparation with minimum removal of tooth structure, restoration with composite material, and sealing of the pit and fissure on the healthy adjacent fissure system, in particular if there is a high risk for new caries lesion develop-

651 Preventive Measures and Minimally Invasive Restorative Procedures

a

b

c

d

..      Fig. 16.7  a Partially retained sealant on the distal groove of the occlusal surface of the maxillary first molar; b fractured sealant on the mandibular second molar, with presence of a carious lesion; c partially

retained sealant on the mandibular first molar; d fracture of sealant of the mandibular second premolar, with presence of carious lesion

ment in this area [145]. Instead of the combination of regular composites with sealants, a flowable composite can be used both for restoring the prepared cavity and for sealing the occlusal pit and fissures [202]. The conservative composite restoration technique includes the following steps: 55 The preparation has to involve only the carious tissue, using an ultraconservative diamond point, a small diameter round diamond point, or a very small tapered carbide bur, in high-speed handpiece, to allow access to the underneath carious dentin (. Fig. 16.8a, b). 55 The caries-infected dentin is removed using a round carbide bur, with diameter compatible to the cavity size, in the low-speed handpiece. Attention has to be directed to the dentin, to maintain the caries-affected demineralized but not infected dentin, capable of remineralization, according to what is described in 7 Chap. 6 (. Fig. 16.8c–e). The rubber dam is placed, and the surface is cleaned using pumice and prophylaxis brush or sodium bicarbonate Prophy-Jet (. Fig. 16.8f). After that, the tooth is thoroughly rinsed and dried with air. 55 Etching is performed with 37% phosphoric acid for 15 s in dentin and for 30 s in enamel margins and the entire fissure system adjacent to the cavity (. Fig. 16.8g).

Surface is thoroughly rinsed for at least 20 s until the entire acid has been removed. Afterwards the area will be gently dried. 55 The adhesive system is applied according to the manufacturers’ instructions (. Fig. 16.8h). 55 Afterwards, the composite is placed (. Fig. 16.8i). Both conventional and flowable composite resins can be used. If the depth of the preparation is more than 2 mm, the incremental technique has to be used, and light-curing will be performed on each increment for 20 s. 55 As a final step of filling, the sealant is applied on the entire adjacent pit and fissure system, according the procedure described above (. Fig. 16.8j). If flowable composite is used, it can be placed both into the prepared cavity and on the grooves. 55 The surface has to be evaluated for voids or bubbles. 55 The rubber dam is removed, and the occlusion has to be evaluated using articulating paper (. Fig. 16.8k). If an adjustment is necessary, fine-grain diamond points, a multibladed finishing bur, or an Arkansas stones can be used to remove it. Finally, polishing has to be performed with abrasive rubber points or polishing pastes with felt points or polishing brushes (. Fig. 16.8l).

 

 

 

 

 

 

 

 

 

 

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Enamel Caries Infiltration

Every dentist regularly comes across incipient enamel carious lesions or white spot lesions in the daily clinical practice. They are characterized by the presence of a pseudo-intact mineralized surface (superficial zone) followed by a demineralized subsurface lesion, also called as lesion body, as described in 7 Chap. 3 (. Fig. 3.4a–d). If a progression of the mineral loss is not stopped by adequate preventive measures,  

 

enamel prisms collapse, the pseudo-intact surface layer will be destroyed, and a cavitation process begins. The treatment of proximal caries lesions generally involves two approaches: the noninvasive (preventive) and the ­invasive (restorative) treatment. When there is no enamel cavitation, noninvasive remineralizing measures involving fluoridation associated to dietary control and oral hygiene counseling represent the first option [203, 204]. However, this approach is not always successful, as it requires compliance and change of

a

b

c

d

e

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..      Fig. 16.8  Conservative composite restoration technique. a Ultraconservative diamond point (on the left) and round diamond point (on the right); b minimum tissue removal to access the carious lesion; c, d removal of the caries-infected dentin; e conservative preparation completed; f prophylaxis with pumice and brush; g acid

etching; h adhesive system application on enamel and dentin; i composite resin application into the preparation; j occlusal surface with composite restoration and sealant on the adjacent grooves; k evaluation of the occlusal contacts; l final aspect of the conservative composite restoration

653 Preventive Measures and Minimally Invasive Restorative Procedures

g

h

i

j

k

l

..      Fig. 16.8 (continued)

patient’s habits. Many patients do not follow the recommendations and give up the treatment prematurely. As a consequence, the lesion can progress, in particular if a high caries risk exists. Cavitation can be the result, requiring an invasive treatment including tooth preparation and restoration. Especially in case of proximal lesions, the preparation of the access cavity is associated with the loss of large amounts of healthy dental tissue [205]. The caries infiltration technique, using very low-viscous resin material, is a new alternative approach in minimally invasive dentistry. As it is not associated with any preparatory measures, it could also be classified as microinvasive.

Different from the pit and fissure sealants that cover the enamel surface with a resin barrier to avoid carious demineralization, this technique aims to fill the pores within the carious lesion with liquid resin material, by penetration of this material into the lesion body, in order to reinforce its weakened structure. This makes the lesion on the one hand more stable against mechanical impacts, in order to avoid the breakdown of the surface layer, and, on the other hand, the dental structure becomes more acid resistant. Both mechanisms should lead to an arrest of its progression to a cavitation stage. Resin infiltration technique represents an intermediate treatment between the prevention and restora-

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tion [205, 206]. This ­procedure, however, does not supersede the well-established preventive strategies. Like any dental treatment, it has to be performed in combination with educational procedures, such as oral hygiene and diet counseling, as well as fluoride application aiming the prevention and control of the caries disease. >> Different from the pit and fissure sealants that cover the enamel surface with a resin barrier to avoid carious demineralization, the resin infiltration technique aims to fill the pores within the carious lesion with liquid resin material, by penetration of this material into the lesion body, in order to reinforce its weakened structure.

16

The infiltration of a carious lesion is not a trivial process, as the superficial layer of the incipient carious lesion is characterized by precipitation of minerals from saliva on the enamel surface and low porosity, blocking the penetration of the resin into the lesion body. Thus, to allow the resin penetration, the superficial zone has to be removed through an erosive procedure using a strong acid. Different acids were tested; however, the sole one able to sufficiently remove the surface layer is 15% hydrochloric acid, applied for 2 min, followed by rinsing with water. To allow the infiltration of the  hydrophobic monomers into the lesion, the etched surface has to be thoroughly dried. For this reason, after drying with airstream, absolute ethanol is applied and has to be dried completely in order to remove the remaining water. This procedure improves the low-viscosity resin (infiltrant) penetration, driven by capillary forces, into the lesion body [207]. The infiltration technique is indicated only to those lesions without cavitation implying that no bacterial contamination within the lesion body has happened. The indication for using it on smooth surfaces of free access can be easily made. However, in the proximal area, the clinical diagnosis of cavitation is quite complex. . Figure  16.9 shows a scheme of the different depths of carious lesions in the proximal area according to the  

radiographic image with the respective treatment option. When nothing is seen, the score E0 is applied. The enamel layer is divided into outer (E1) and inner halves (E2), while dentin between the dentin enamel junction and the pulp is divided into three thirds (outer, D1; middle, D2; and, inner, D3) [208]. Studies comparing the radiographic images with the actual presence of cavitation showed that E1 lesions never had cavitation, while E2 is cavitated in 10–19.3% of the cases [209, 210]. However, 32% D1 lesions were cavitated, while 72% of lesions extending into the inner 2/3 (D2 and D3) of the dentin also showed cavitation [211]. In addition, some studies observed that when the radiolucency reaches the inner third of dentin (D3), cavitation was present in 100% of the cases [209, 210]. The resin infiltration technique is indicated for caries lesions in the proximal region with radiographic image up to external third of the dentin (D1), expecting that more than 2/3 of the cases are free of cavitation [211]. However, some studies showed a high prevalence of cavitation even in D1 lesions [212, 213]. This way, regular radiographic examination is recommended on cases where the infiltration technique has been performed, mainly on situation where the radiolucency reaches the dentin. The best way to have a more predictable evaluation of presence of cavitation is to perform a temporary elective tooth separation, followed by impression with a silicone material [214], as described on 7 Chap. 3. In each case when a cavitation is present, this technique is not indicated, and a restoration is required, since at that stage, bacterial penetration into the lesion has already occurred.  

>> Infiltration technique can be used only in case of non-cavitated lesions. The deeper a proximal lesion is, the higher the probability that a cavitation is present. In case of cavitation, an infiltration is not indicated, and a restoration has to be placed.

To allow the resin application in the proximal lesion, a small tooth separation is required using wedges in the proximal space. Then, a special applicator device, a foil matrix delivery

..      Fig. 16.9  Different depths of carious lesions according to the radiographic image and the treatment indications. E0, no lesion; E1, outer enamel; E2, inner enamel; D1, outer third of dentin; D2, middle third of dentin; D3, inner third of dentin

655 Preventive Measures and Minimally Invasive Restorative Procedures

a

b

..      Fig. 16.10  a Proximal tip foil matrix delivery system with micro-perforations in only one of the sides; b hydrochloric acid gel passing through the perforations of the matrix

system that contains micro-perforations, has to be put into the proximal space. The perforations point towards one of the sides. This allows the product application only to the affected proximal region, protecting the sound adjacent surface (. Fig. 16.10a, b). The treatment protocol for proximal surfaces includes the following steps (. Fig. 16.11a–o): 55 Making of bitewing radiography for lesion diagnosis (. Fig. 16.11a, b) 55 Cleaning of the teeth with prophylaxis paste and brush and of the proximal surfaces with dental floss 55 Isolation of teeth with rubber dam in order to avoid any harm by use of the strong hydrochloric acid 55 Separation of teeth using a wedge, which allows the placement of the delivery device into the proximal region (. Fig. 16.11c) 55 Connection of the applicator with the hydrochloric acid syringe, insertion of foil matrix between the teeth, and application of the acid for 2 min (. Fig. 16.11d, e) 55 Removal of the applicator and rinsing with water for at least 30 s; drying with air (. Fig. 16.11f) 55 Connection of a new applicator with the ethanol syringe, placement of it into the interproximal space, application of the ethanol onto the lesion and incubation for 30 s; drying with air (. Fig. 16.11g) 55 Connection of a new applicator with the infiltrant syringe, placement into the proximal space, application of the infiltrant, and incubation for 3 min. Removal of the applicator and of any excess of the infiltrant with dental floss. Light-curing of the infiltrant for 40 s from all sides (occlusal, buccal, and lingual) (. Fig. 16.11h–k) 55 Rerunning of the last step, incubation for 1 min, and light-curing from all sides for 40 s (. Fig. 16.11l) 55 Polishing with fine grit polishing strips (. Fig. 16.11m, n)  

 

 

 

 

 

 

 

 

 

One has to bear in mind that the infiltrant is not radiopaque; therefore, a radiographic observation of the infiltrant penetration into the lesion is not possible (. Fig. 16.11o). This is even more important if the patient changes the dentist.  

Furthermore, any follow-up can only be done indirectly via the estimation whether there is a lesion progression on periodically made bitewing radiographs. It is very important for monitoring that the radiographs have always the same direction. A recent systematic review revealed that proximal caries lesion progression was less likely to occur in permanent teeth being infiltrated with resin material as compared to noninvasive methods, provided that oral hygiene instructions and measures were performed [215, 216]. The evidence is at this moment moderate to low, due to lack of high number of studies. However, further newer studies not included in the review show also quite positive results, in particular in patients with high risk [217]. A second indication of the infiltration technique is the color masking of initial carious lesions on smooth surfaces. If an initial carious lesion occurs, the teeth get a whitish or chalky appearance (white spot lesion). The whitish color is due to the increase of the intercrystalline spaces of the demineralized enamel  and creation of a high porous area, which changes its the refractive index (RI). While the sound enamel has a RI of 1.65, the lesion pores will be filled with water, which has a RI of 1.33, or air (RI of 1.00). In this case, the light waves reach multiples interfaces between the fluid and the mineral phase, with different refractive indices. At each interface the light is deviated and reflected, becoming imprisoned in an “optical maze” that is over-luminous and therefore perceived as white [218, 219]. The infiltrant has a refractive index of 1.475, closer to sound enamel, resulting in a masking effect of the white spot lesion, if deeply penetrated into the micropores, and in an improvement of the esthetics [220–222]. Typically, white spot lesions on the smooth surfaces occur due to inadequate oral hygiene, e.g., during an orthodontic treatment with brackets. The brackets are biofilm retention sites; however, white spots can also occur without orthodontic treatment in case of insufficient general oral hygiene. Usually, oral hygiene education and the application of fluorides are recommended to enhance remineralization of white spot lesions. However, this procedure is not successful in

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a

b

c

d

e

f

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..      Fig. 16.11  Resin infiltration protocol for incipient proximal caries lesion. a Initial case without clinical evidence of cavitation; b radiographic image suggesting enamel carious lesion on distal surface of maxillary first premolar; c rubber dam isolation and tooth separation with the plastic wedge; d placement of the proximal-tip foil matrix applicator in the proximal region, with the perforations directed to the affected tooth surface; e application of the hydrochloric acid; f rinsing

and drying; g application of ethanol; h application of the infiltrant resin; i–k light-curing from occlusal, buccal, and lingual sides; l reapplication of the infiltrant resin, followed by light-curing; m polishing with fine-grain abrasive strip; n final case; o absence of radiographic evidence of the infiltrant resin, since the material is not radiopaque

657 Preventive Measures and Minimally Invasive Restorative Procedures

g

h

i

j

k

l

..      Fig. 16.11 (continued)

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m

n

o

..      Fig. 16.11 (continued)

16

all cases and is dependent on the patients’ compliance. The infiltration technique is a possible alternative. However, in cases of inactive but still visible lesions, in which the surface layer is thick and the lesion is in parts remineralized, the success is often limited, most likely due to an incomplete infiltration of the lesion. This is the case if the surface of the white spot has a glossy instead of a frosty appearance or shows even a discoloration. The technique for application is comparable to that of proximal lesions except for the application device. Isolation of the teeth is, as mentioned for the proximal lesions, a prerequisite. Both a conventional rubber dam and a liquid dam are possible, depending on the extension of the lesion. The patient should be informed about potential changes in color and about the possibility of failure. . Figure  16.12a–i shows a clinical case of infiltration of white spot lesions as a sequela of bad hygine during  orthodontic treatment (. Fig.  16.12a). The following steps have been performed: isolation of the teeth using a light-curing liquid dam, application of the hydrochloric acid for 2  min (. Fig. 16.12b), and rinsing for 20 s (. Fig. 16.12c). The step was followed by air-drying, ethanol application, and drying for 30 s each (. Fig. 16.12d, e). Afterwards, the infiltrant was

applied for 3 min (. Fig. 16.12e). Excess was removed, and the infiltred surfaces were light-cured for 40 s. The infiltrant application was repeated for 1 min and light-cured again for 40 s (. Fig. 16.12f). Finally, the surfaces were polished with abrasive discs to remove any excess and create a smooth surface. After these procedures, it was observed that the white spot lesions’ masking was effective (. Fig. 16.12g–i) Due to histological structural similarities between carious white spot lesions and fluorotic enamel, the infiltration procedure can also be used in such cases. First clinical studies showed good results [223], and it appears to be a promising strategy [224]. In case of other hypomineralization such as in case of molar incisor hypomineralization (MIH), the results are less promising, mainly due to differences in histological structure.  

 

 

 

Tip

 

 

 

 

Besides arresting proximal caries lesion, the resin infiltration can promote a color-masking effect of carious white spot lesions and fluorotic enamel, on labial surface of anterior teeth, resulting in esthetic improvement.

659 Preventive Measures and Minimally Invasive Restorative Procedures

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b

c

d

e

f

..      Fig. 16.12  a Initial situation showing white spot lesions; b isolation with light-curing gingival barrier and application of the etching gel; c rinsed teeth after etching with wet surface; d dried teeth, showing the frosty-white appearance of the enamel; e application of ethanol using

a smooth surface tip; f application of the infiltrant resin; g aspect immediately after the infiltrant application; h final result

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g

h

i

..      Fig. 16.12 (continued)

Conclusion

16

In modern preventive dentistry, micro- and minimally invasive strategies are the key components, superseding the traditional dentistry, which was based on the restorative-surgical model. The reestablishment of the shape, function, and esthetics of the lost tooth structures has been forced back, and approaches that emphasize health promotion and disease prevention, representing a great advance in direction to the oral health maintenance, are paramount. Contemporary preventive strategies comprise caries risk identification, prevention of development and progression of incipient lesion, remineralization of initial lesions, sealing of fissures to avoid biofilm accumulation in the retentive occlusal area, minimally invasive (conservative) preparation for fillings, and repair of the defective restorations instead of its replacement. To reach this goal, the dentist must be proficient in the etiology, pathogenesis, and development of caries as a disease, as well as in the early diagnosis of carious lesions. That will allow the implementation of reasonable i­ndividual-based preventive and minimally invasive strategies, together with measures that reduce or eliminate the causes of the caries disease, reducing their recurrence with the goal to optimally preserve the dental structures.

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128. Vacca-Smith AM, Van Wuyckhuyse BC, Tabak LA, Bowen WH. The effect of milk and casein proteins on the adherence of Streptococcus mutans to saliva-coated hydroxyapatite. Arch Oral Biol. 1994;39:1063–9. 129. Ametani A, Kaminogawa S, Shimizu M, Yamauchi K. Rapid screening of antigenically reactive fragments of alpha s1-casein using HPLC and ELISA. J Biochem (Tokyo). 1987;102:421–5. 130. Cochrane NJ, Saranathan S, Cai F, Cross KJ, Reynolds EC.  Enamel subsurface lesion remineralisation with casein phosphopeptide stabilised solutions of calcium, phosphate and fluoride. Caries Res. 2008;42:88–97. https://doi.org/10.1159/000113161. 131. Schirrmeister JF, Seger RK, Altenburger MJ, Lussi A, Hellwig E. Effects of various forms of calcium added to chewing gum on initial enamel carious lesions in situ. Caries Res. 2007;41:108–14. https://doi.org/10.1159/000098043. 132. Lennon AM, Pfeffer M, Buchalla W, Becker K, Lennon S, Attin T.  Effect of a casein/calcium phosphate-containing tooth cream and fluoride on enamel erosion in vitro. Caries Res. 2006;40:154–7. 133. Manton DJ, Cai F, Yuan Y, Walker GD, Cochrane NJ, Reynolds C, et al. Effect of casein phosphopeptide-amorphous calcium phosphate added to acidic beverages on enamel erosion in vitro. Aust Dent J. 2010;55:275–9. https://doi.org/10.1111/j.1834-7819.2010.01234.x. 134. Taha AA, Patel MP, Hill RG, Fleming PS.  The effect of bioactive glasses on enamel remineralization: a systematic review. J Dent. 2017;67:9–17. https://doi.org/10.1016/j.jdent.2017.09.007. 135. Haghgoo R, Ahmadvand M, Moshaverinia S. Remineralizing effect of topical NovaMin and Nano-hydroxyapatite on caries-like lesions in primary teeth. J Contemp Dent Pract. 2016;17:645–9. 136. Nagayoshi M, Kitamura C, Fukuizumi T, Nishihara T, Terashita M.  Antimicrobial effect of ozonated water on bacteria invading dentinal tubules. J Endod. 2004;30:778–81. 137. Baysan A, Beighton D. Assessment of the ozone-mediated killing of bacteria in infected dentine associated with non-cavitated occlusal carious lesions. Caries Res. 2007;41:337–41. 138. Lynch E.  Evidence-based caries reversal using ozone. J Esthet Restor  Dent. 2008;20:218–22. https://doi.­org/10.1111/­j.17088240.2008.00183.x. 139. Azarpazhooh A, Limeback H. The application of ozone in dentistry: a systematic review of literature. J Dent. 2008;36:104–16. https:// doi.org/10.1016/j.jdent.2007.11.008. 140. Brazzelli M, McKenzie L, Fielding S, Fraser C, Clarkson J, Kilonzo M, et al. Systematic review of the effectiveness and cost-­effectiveness of HealOzone for the treatment of occlusal pit/fissure caries and root caries. Health Technol Assess. 2006;10:iii-80. 141. Sun J, Yang X, Xu QA, Bian Z, Chen Z, Fan M. Protective efficacy of two new anti-caries DNA vaccines. Vaccine. 2009;27:7459–66. 142. Soderling E, Isokangas P, Pienihakkinen K, Tenovuo J, Alanen P.  Influence of maternal xylitol consumption on mother-child transmission of mutans streptococci: 6-year follow-up. Caries Res. 2001;35:173–7. 143. Santin GC, Oliveira DS, Galo R, Borsatto MC, Corona SA. Antimicrobial photodynamic therapy and dental plaque: a systematic review of the literature. Scientific World J. 2014;2014:824538. 144. Santos A. Evidence-based control of plaque and gingivitis. J Clin Periodontol. 2003;30(Suppl 5):13–6. 145. Roberson TM, Heymann HO, Ritter AV, Pereira PN. Class I, II and VI direct composite and other tooth-colored restoration. In: Roberson TM, Heymann HO, Swift Jr EJ, editors. Sturdevants Art Sci. Oper. Dent. Mosby: Elsevier; 2006. p. 567–99. 146. Feigal RJ, Donly KJ.  The use of pit and fissure sealants. Pediatr Dent. 2006;28:143–50; 198. 147. Fejerskov O, Kidd EA.  Dental caries: the disease and its clinical management, vol. 4. Munksgaard: Wiley-Blackwell; 2015. 148. Simonsen RJ.  Pit and fissure sealant: review of the literature. ­Pediatr Dent. 2002;24:393–414. 149. Bekes K. Pit and fissure sealants: Springer International Publishing; 2018.

150. Kidd E, Joyston-Bechal S.  Essentials of dental caries. Oxford: New York; 1997. 151. Rethman J. Trends in preventive care: caries risk assessment and indications for sealants. J Am Dent Assoc. 2000;131:8S–12S. 152. Axelsson P.  Preventive materials, methods and programs. Berlin: Quintessence Publishing; 2004. 153. Kotsanos N, Darling AI. Influence of posteruptive age of enamel on its susceptibility to artificial caries. Caries Res. 1991;25:241–50. https://doi.org/10.1159/000261371. 154. Simonsen RJ. Pit and fissure sealant: Then, now, and next steps. J Public Health Dent. 2004;64:17–22. 155. Wright JT, Tampi MP, Graham L, Estrich C, Crall JJ, Fontana M, et al. Sealants for preventing and arresting pit-and-fissure occlusal caries in primary and permanent molars. Pediatr Dent. 2016;38:282–308. 156. Griffin SO, Oong E, Kohn W, Vidakovic B, Gooch BF, CDC Dental Sealant Systematic Review Work Group, et al. The effectiveness of sealants in managing caries lesions. J Dent Res. 2008;87:169–174. https://doi.org/10.1177/154405910808700211. 157. Handelman SL. Therapeutic use of sealants for incipient or early carious lesions in children and young adults. Proc Finn Dent Soc Suom Hammaslaakariseuran Toim. 1991;87:463–75. 158. Handelman SL, Leverett DH, Espeland MA, Curzon JA.  Clinical radiographic evaluation of sealed carious and sound tooth surfaces. J Am Dent Assoc 1939. 1986;113:751–4. 159. Going RE, Loesche WJ, Grainger DA, Syed SA. The viability of microorganisms in carious lesions five years after covering with a fissure sealant. J Am Dent Assoc 1939. 1978;97:455–62. 160. Handelman SL, Washburn F, Wopperer P. Two-year report of sealant effect on bacteria in dental caries. J Am Dent Assoc. 1939;1976(93):967–70. 161. Oong EM, Griffin SO, Kohn WG, Gooch BF, Caufield PW. The effect of dental sealants on bacteria levels in caries lesions: a review of the evidence. J Am Dent Assoc 1939. 2008;139:271–8; quiz 357-8. 162. Wright JT, Crall JJ, Fontana M, Gillette EJ, Nový BB, Dhar V, et  al. Evidence-based clinical practice guideline for the use of pit-­and-­ fissure sealants: a report of the American Dental Association and the American Academy of Pediatric Dentistry. J Am Dent Assoc 1939. 2016;147:672–682.e12. https://doi.org/10.1016/j. adaj.2016.06.001. 163. Bakhshandeh A, Qvist V, Ekstrand KR.  Sealing occlusal caries lesions in adults referred for restorative treatment: 2-3 years of follow-­ up. Clin Oral Investig. 2012;16:521–9. https://doi. org/10.1007/s00784-011-0549-4. 164. Borges BC, Campos GB, da Silveira AD, de Lima KC, Pinheiro IV. Efficacy of a pit and fissure sealant in arresting dentin non-­cavitated caries: a 1-year follow-up, randomized, single-blind, controlled clinical trial. AmJ Dent. 2010;23:311–6. 165. Borges BCD, de Souza Borges J, Braz R, Montes MAJR, de Assunção Pinheiro IV. Arrest of non-cavitated dentinal occlusal caries by sealing pits and fissures: a 36-month, randomised controlled clinical trial. Int Dent J. 2012;62:251–5. https://doi.org/10.1111/j.1875-595X.2012.00117.x. 166. da Silveira ADS, Borges BCD, de Almeida Varela H, de Lima KC, Pinheiro IV de A.  Progression of non-cavitated lesions in dentin through a nonsurgical approach: a preliminary 12-month clinical observation. Eur J Dent. 2012;6:34–42. 167. Borges BCD, De Souza Bezerra Araújo RF, Dantas RF, De Araújo LA, De Assunção Pinheiro IV.  Efficacy of a non-drilling approach to manage non-cavitated dentin occlusal caries in primary molars: a 12-month randomized controlled clinical trial. Int J Paediatr Dent. 2012;22:44–51. https://doi.org/10.1111/j.1365-263X.2011.01156.x. 168. Davis RD.  Patient evaluation and problem-oriented treatment planning. In: Schwartz RS, Summitt JB, Robbins JW, editors. Fundam. Oper. Dent. Contemp. Approach. Illinois: Quintessence Publishing; 1996. p. 27–50. 169. Hevinga MA, Opdam NJM, Frencken JE, Bronkhorst EM, Truin GJ. Can caries fissures be sealed as adequately as sound fissures? J Dent Res. 2008;87:495–8. https://doi.org/10.1177/154405910808700514.

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170. Houpt M, Fuks A, Shapira J, Chosack A, Eidelman E. Autopolymerized versus light-polymerized fissure sealant. J Am Dent Assoc 1939. 1987;115:55–6. 171. Shapira J, Fuks A, Chosack A, Houpt M, Eidelman E. Comparative clinical study of autopolymerized and light-polymerized fissure sealants: five-year results. Pediatr Dent. 1990;12:168–9. 172. Lobo MM, Pecharki GD, Tengan C, da Silva DD, da Tagliaferro EPS, Napimoga MH.  Fluoride-releasing capacity and cariostatic effect provided by sealants. J Oral Sci. 2005;47:35–41. 173. Yildiz E, Dörter C, Efes B, Koray F. A comparative study of two fissure sealants: a 2-year clinical follow-up. J Oral Rehabil. 2004;31:979–84. https://doi.org/10.1111/j.1365-2842.2004.01334.x. 174. Lygidakis NA, Oulis KI. A comparison of Fluroshield with Delton fissure sealant: four year results. Pediatr Dent. 1999;21:429–31. 175. Mascarenhas AK, Nazar H, Al-Mutawaa S, Soparkar P. Effectiveness of primer and bond in sealant retention and caries prevention. Pediatr Dent. 2008;30:25–8. 176. Feigal RJ, Musherure P, Gillespie B, Levy-Polack M, Quelhas I, Hebling J. Improved sealant retention with bonding agents: a clinical study of two-bottle and single-bottle systems. J Dent Res. 2000;79:1850–6. https://doi.org/10.1177/00220345000790110601. 177. Hebling J, Feigal RJ. Use of one-bottle adhesive as an intermediate bonding layer to reduce sealant microleakage on saliva-­ contaminated enamel. Am J Dent. 2000;13:187–91. 178. Yazici AR, Bayazit EO, Kutuk ZB, Ozgunaltay G, Ergin E, Berber A.  Clinical follow-up of a fissure sealant placed using different adhesive protocols: a 24-month Split-mouth study. Oper Dent. 2018;43:362–71. https://doi.org/10.2341/17-055-C. 179. Fumes AC, Longo DL, De Rossi A, Fidalgo TK d S, de Paula E, Silva FWG, Borsatto MC, et al. Microleakage of sealants after phosphoric acid, Er: YAG laser and air abrasion enamel conditioning: systematic review and meta-analysis. J Clin Pediatr Dent. 2017;41:167–72. https://doi.org/10.17796/1053-4628-41.3.167. 180. Gillcrist JA, Vaughan MP, Plumlee GN, Wade G.  Clinical sealant retention following two different tooth-cleaning techniques. J Public Health Dent. 1998;58:254–6. 181. Autio-Gold JT.  Clinical evaluation of a medium-filled flowable restorative material as a pit and fissure sealant. Oper Dent. 2002;27:325–9. 182. Corona SA, Borsatto MC, Garcia L, Ramos RP, Palma-Dibb RG. Randomized, controlled trial comparing the retention of a flowable restorative system with a conventional resin sealant: one-year follow up. Int J Paediatr Dent. 2005;15:44–50. https://doi.org/10.1111/ j.1365-263X.2005.00605.x. 183. Dukic W, Glavina D. Clinical evaluation of three fissure sealants: 24 month follow-up. Eur Arch Paediatr Dent. 2007;8:163–6. 184. Papacchini F, Goracci C, Sadek FT, Monticelli F, Garcia-Godoy F, Ferrari M.  Microtensile bond strength to ground enamel by glass-­ ionomers, resin-modified glass-ionomers, and resin composites used as pit and fissure sealants. J Dent. 2005;33:459–67. https:// doi.org/10.1016/j.jdent.2004.11.007. 185. Van Meerbeek B, Yoshihara K, Yoshida Y, Mine A, De Munck J, Van Landuyt KL.  State of the art of self-etch adhesives. Dent Mater. 2011;27:17–28. https://doi.org/10.1016/j.dental.2010.10.023. 186. Burbridge L, Nugent Z, Deery C. A randomized controlled trial of the effectiveness of a one-step conditioning agent in fissure sealant placement: 12 month results. Eur Arch Paediatr Dent. 2007;8:49–54. 187. dos Santos KT, Sundfeld RH, Garbin CAS, de Alexandre RS, Sundefeld MLMM, Ceolim BN. Length of resin tags in pit-and-fissure sealants: all-in-one self-etching adhesive vs phosphoric acid etching. Compend Contin Educ Dent Jamesburg NJ 1995. 2008;29:186–92. 188. Poulsen S, Beiruti N, Sadat N. A comparison of retention and the effect on caries of fissure sealing with a glass-ionomer and a resinbased sealant. Community Dent Oral Epidemiol. 2001;29:298–301. 189. Mickenautsch S, Yengopal V.  Caries-preventive effect of high-­ viscosity glass ionomer and resin-based fissure sealants on perma-

nent teeth: a systematic review of clinical trials. PloS One. 2016;11:e0146512. https://doi.org/10.1371/journal.pone.0146512. 190. Forss H, Saarni UM, Seppä L.  Comparison of glass-ionomer and resin-based fissure sealants: a 2-year clinical trial. Community Dent Oral Epidemiol. 1994;22:21–4. 191. Torppa-Saarinen E, Seppä L. Short-term retention of glass-­ionomer fissure sealants. Proc Finn Dent Soc Suom Hammaslaakariseuran Toim. 1990;86:83–8. 192. Antonson SA, Antonson DE, Brener S, Crutchfield J, Larumbe J, Michaud C, et al. Twenty-four month clinical evaluation of fissure sealants on partially erupted permanent first molars: glass ionomer versus resin-based sealant. J Am Dent Assoc 1939. 2012;143:115–22. 193. Pardi V, Pereira AC, Ambrosano GMB, Meneghim Mde C.  Clinical evaluation of three different materials used as pit and fissure sealant: 24-months results. J Clin Pediatr Dent. 2005;29:133–7. 194. Dewji HR, Drummond JL, Fadavi S, Punwani I. Bond strength of BisGMA and glass ionomer pit and fissure sealants using cyclic fatigue. Eur J Oral Sci. 1998;106:594–9. 195. Smales RJ, Gao W, Ho FT. In vitro evaluation of sealing pits and fissures with newer glass-ionomer cements developed for the ART technique. J Clin Pediatr Dent. 1997;21:321–3. 196. Simonsen RJ.  Retention and effectiveness of dental sealant after 15 years. J Am Dent Assoc 1939. 1991;122:34–42. 197. Wendt LK, Koch G. Fissure sealant in permanent first molars after 10 years. Swed Dent J. 1988;12:181–5. 198. Wendt LK, Koch G, Birkhed D. On the retention and effectiveness of fissure sealant in permanent molars after 15–20 years: a cohort study. Community Dent Oral Epidemiol. 2001;29:302–7. 199. Ahovuo-Saloranta A, Forss H, Walsh T, Nordblad A, Mäkelä M, Worthington HV.  Pit and fissure sealants for preventing dental decay in permanent teeth. Cochrane Database Syst Rev. 2017;7:CD001830. https://doi.org/10.1002/14651858.CD001830. pub5. 200. Simonsen RJ, Stallard RE.  Sealant-restorations utilizing a diluted filled composite resin: one year results. Quintessence Int Dent Dig. 1977;8:77–84. 201. Simonsen RJ. The preventive resin restoration: a minimally invasive, nonmetallic restoration. Compend Newtown Pa. 1987;8:428– 30, 432. 202. Qin M, Liu H. Clinical evaluation of a flowable resin composite and flowable compomer for preventive resin restorations. Oper Dent. 2005;30:580–7. 203. Yamazaki H, Litman A, Margolis HC. Effect of fluoride on artificial caries lesion progression and repair in human enamel: regulation of mineral deposition and dissolution under in  vivo-like conditions. Arch Oral Biol. 2007;52:110–20. https://doi.org/10.1016/j. archoralbio.2006.08.012. 204. Young DA, Kutsch VK, Whitehouse J. A clinician’s guide to CAMBRA: a simple approach. Compend Contin Educ Dent Jamesburg NJ 1995 2009;30:92–94, 96, 98, passim. 205. Phark J-H, Duarte S, Meyer-Lueckel H, Paris S.  Caries infiltration with resins: a novel treatment option for interproximal caries. Compend Contin Educ Dent. 2009;30 Spec No 3:13–7. 206. Paris S, Meyer-Lueckel H. Inhibition of caries progression by resin infiltration in situ. Caries Res. 2010;44:47–54. https://doi. org/10.1159/000275917. 207. Meyer-Lueckel H, Paris S.  Progression of artificial enamel caries lesions after infiltration with experimental light curing resins. Caries Res. 2008;42:117–24. https://doi.org/10.1159/000118631. 208. Anusavice KJ. Present and future approaches for the control of caries. J Dent Educ. 2005;69:538–54. 209. Akpata ES, Farid MR, al-Saif K, Roberts EA. Cavitation at radiolucent areas on proximal surfaces of posterior teeth. Caries Res. 1996;30:313–6. https://doi.org/10.1159/000262336. 210. Pitts NB, Rimmer PA.  An in  vivo comparison of radiographic and directly assessed clinical caries status of posterior approximal sur-

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Aesthetic Veneers: What Are They and How to Handle Them? Maria Filomena Rocha Lima Huhtala, Clovis Pagani, Carlos Rocha Gomes Torres, Pekka Kalevi Vallittu, and Jukka Pekka Matinlinna 17.1

Introduction – 668

17.2

Basic Principles for Veneer Preparation – 669

17.3

Sequence of Tooth Preparation – 673

17.4

Direct Veneer Restoration – 678

17.5

Indirect Veneers – 681

17.5.1 17.5.2 17.5.3 17.5.4 17.5.5 17.5.6 17.5.7 17.5.8

 ental Ceramics – 681 D Impression/Scanning of the Tooth Preparation – 682 Provisional Restoration – 682 Extraoral Phase for Indirect Restoration – 682 Try-in Procedure – 683 Pretreatment of Veneers – 683 Cementation of Indirect Veneers – 686 Finishing and Polishing – 686

17.6

 hanges of the Apparent Tooth Dimension by Optical C Illusions – 686

17.6.1 17.6.2

F lat Area – 686 Embrasures – 688

References – 689

© Springer Nature Switzerland AG 2020 C. R. G. Torres (ed.), Modern Operative Dentistry, Textbooks in Contemporary Dentistry, https://doi.org/10.1007/978-3-030-31772-0_17

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Learning Objectives The learning objectives of this chapter are related to the following topics: 55 Indications and contraindications for veneers 55 Clinical steps for tooth preparation 55 Direct resin composite veneers 55 Mock-ups and impressions for indirect veneers 55 Ceramics used as an indirect veneering material 55 Pretreatment, silanization of veneers, and luting 55 Changes of the apparent tooth dimension by optical illusions

17.1 

17

Introduction

Facial aesthetics plays an important role on an individual’s well-being, self-esteem, emotional condition, social success, and even chances to get a job. The smile is primordial in the search for an optimum dentofacial aesthetic standard. An aesthetic smile depends on the harmony of shapes and shades of anterior teeth. In addition, the alignment of these teeth and their harmonic positioning on the arch are the basics to obtain this aesthetic balance [1–3]. However, teeth are not always distributed on a harmonic way on the dental arch. This lack of harmony may have different origins, such as genetic or developmental tooth anomalies, structural changes caused by caries, and chromatic changes or injuries in the dental structure due to traumas. When these alterations take place on the labial surface of anterior teeth, or even on the buccal surface of premolars, one treatment option can be the total covering of the surface using a restoration called a laminate, veneer, or facet. This restoration is used to cover an unsightly area by bonding to the facial surface of the prepared tooth [4]. By and large, veneers can be made either by a direct technique, using resin composite, or by an indirect technique using composite or dental ceramic. In dentistry, composites are indicated for direct and indirect restorations or as a luting cement, due to its light-­curing of self-curing mechanism, while ceramics are used to prepare indirect restorations, because require a laboratorial firing step for its manufacturing. Resin composite materials consist of five key components: (a) organic monomer (resinous) matrix, (b) Si-­based glass fillers (for strength and X-ray opacity), (c) a silane coupling agent (for adhesion promotion), (d) pigments (for aesthetics), and (e) activators, inhibitors, and stabilizers (for setting reactions) [5, 6]. Veneering doesn’t aim only aesthetic recovery but also preservation of tooth structure, limiting the periodontal and pulp involvement that may result from more invasive procedures, such as full crown preparations. However, the clinical success of a dental restorations will depend on several clinical steps, such as the tooth preparation, bonding procedures and cementation (for the indirect ones). It is noteworthy that adhesion takes places (at least) in two levels: on the one hand, between prepared tooth tissue and, on the other hand, between resin composite cement and dental indirect restor-

ative materials (of which the laminate is prepared). Adhesion can be of chemical or retentive nature (macromechanical or micromechanical retention). Chemical adhesion takes place when the two dissimilar materials are close in a molecular level and contact to form chemical bonds [7, 8]. Dentin bonding is understood to be based predominantly on micromechanical retention and is beyond the scope of this chapter [9, 10]. At the chairside, the preparation for laminate veneers starts with structural reduction of facial surfaces and must generally be made only on enamel, even though in several situations, they also involve the superficial layer of dentin. However, those preparations must avoid unnecessary removal of dentin, not only due to pulpal damage but also because the bonding to etched enamel is always better than to dentin. Aesthetic results with this technique are very good, due to the  reproduction of the original shade and translucency [11, 12]. The concept of coverage of the labial surface of anterior teeth due to aesthetic reasons started back in the 1930s, when Dr. Charles Pincus introduced the technique of ceramic veneers, to attend aesthetic demands of Hollywood artists [13]. It is well-known that the American cinema played an important role on culture and people behavior worldwide, and this demand had the merit to call the attention of dentists, who until then had the aim to restore mainly function and occlusion of teeth than to restore the aesthetics. However, those labial surface coverages with a very thin layer of ceramic bonded to teeth were very expensive, and only a few people had access to it. On an attempt to reduce cost, clinicians start to cover the labial surfaces of teeth with direct composite resin veneers. However, results were limited due to the aesthetic quality of restorative materials available at that time and the little retention that adhesive systems provided. After the 1980s, the development led to new bonding techniques, including the so-called adhesive resin composite cements [14, 15]. The further development on the composite sicience become possible to obtain direct restorations that are very similar to tooth structure with esthetic results close to those obtained with the ceramics, leading to a even  broader use of the technique of labial coverage of teeth [2, 16, 17]. Direct aesthetic veneers can be a very practical intervention and the tooth preparation is usually limited to the labial surface of the teeth. However, for indirect veneers, the preparation generally goes further than this surface and additional steps are necessary, such as impression of the prepared area, temporary restorations, and laboratorial procedures [1, 18]. The  tooth preparation  for direct venners is generally more conservative and, in some specific situations, the restorations can be done even without the need of any preparation, e.g., lingually positioned teeth in relation to the adjacent ones. Direct veneer restoration is therefore a faster technique and can be finished in a single appointment. Among the indications for veneers are the teeth with discoloration, such as those affected by amelogenesis imperfecta, physiological aging, trauma, fluorosis, or stains caused by

669 Aesthetic Veneers: What Are They and How to Handle Them?

tetracycline intake. However, it is vital to note that dental bleaching should always be the first treatment choice in those cases, because it is much more conservative and does not require any cutting of tooth structure. Therefore, only teeth that do not show a satisfactory response to bleaching should receive veneers. Other indications include teeth with extensive caries lesions or fractures, presence of multiple restorations with unsatisfactory shade, rotated or inclined teeth, necessity of reduction and closing of diastemas, short teeth which require increasing of its length, misshapen peg-shaped maxillary lateral incisor, microdontia and Hutchinson’s incisors, aesthetic transformation (canines into lateral incisors and lateral into central incisors), alignment of teeth on the dental arch, and, finally, anterior or premolar teeth with extensive non-carious lesions. The contraindications for veneers are patients with bruxism, parafunctional oral habit, edge-to-edge occlusion of the anterior teeth, anterior teeth with large destruction of the crown, when there is not enough remaining tooth structure to support the veneer, high caries  disease activity associated with bad oral hygiene, periodontal disease, and teeth with excessive labial inclination. In this last situation, a preparation would likely result in exposure of the pulp. Veneers allow very good aesthetical results because the entire coverage of the tooth labial surface produces harmony of shade and shape of the teeth. Veneers also allow the adjustment of individual aesthetic parameters using characterization colored materials. The large variety of resin composites  and resin cements, with different shades and translucency, allow to achieve adequate aesthetic standards in relation to the adjacent teeth [1, 11, 16, 19, 20]. Indirect ceramic veneers have greater durability and color stability and do not suffer abrasion or discoloration. Conversely, for direct resin composite veneers, this color stability depends on factors inherent not only to the composite used but also to some patient’s habits. Frequent consumption of food and/or beverages with dyes, as well as smoking habit diminishes the  veneer durability. Another disadvantage of the direct veneers is the need of the clinician’s skills to create the aesthetic characteristics, such as shape, texture, contour, and shade. Thus, direct procedure takes more time and is less indicated when all anterior teeth need to be covered by a veneer. There is also the possibility of incorporation of air bubbles during the composite layer application, therefore creating areas even more  susceptible to staining and degradation. In the case of highly discolored teeth, it is hard to obtain adequate color match and natural translucency with direct veneers, because the slight depth of tooth preparation does not allow enough composite thickness to mask the dark background. Opaque masking agents can be used to hide the dark background under the restoration. However, the thickness of the composite layer applied over it will hardly be enough to allow recovering the natural translucence of the tooth. A complete cosmetic change of all anterior teeth can be accomplished using veneers. Not only the color but the shape,

size, position within the arch, and surface characteristics can be modified. Before that, a treatment simulation can be performed with a diagnostic wax-up in a plaster model, quickly previewing the effects of the laminates, allowing the analysis of the intended treatment by the patient. Another option is to perform a digital smile design, using a picture of the patient’s teeth or a previous intraoral scanning. In the latter case, a 3D printing can be performed, obtaining a resin model which is shown to the patient. Using the wax-up or 3D model of the proposed treatment, an intraoral mock-up can be produced. For that a trayless impression of the wax-up or resin model is performed using a putty silicone impression material. The labial side of the matrix is trimmed in the interproximal regions to allow the excess material overflow. A bis-acryl composite is applied inside the matrix and seated. After curing, an intraoral mock­up will allow the patient previewing of the final treatment outcome. That can also be used as a guide during the tooth preparation [21, 22]. >> It is necessary for the clinician to identify when direct resin composite veneers are the option and when indirect ceramic veneers are preferable. This should be based on a comprehensive evaluation of the patient, bearing in mind indications and contraindications and the anticipated aesthetic outcome.

17.2 

Basic Principles for Veneer Preparation

The preparation for direct veneers is very conservative as only a thin layer of the labial tooth surface is removed. The depth of the preparation will depend on the area of the tooth, intensity of chromatic alteration, shape, and position. In relation to the area of the tooth, because the preparation should be preferably performed only on enamel, it should be kept in mind the enamel thickness on each part of the crown, thus avoiding reaching dentin. It is known that the thickness of the enamel in the cervical region on the upper central incisors ranges from 0.5 to 0.7 mm, on the medium third from 1.1 to 1.4 mm, and from 1.2 to 1.8 mm on the incisal third. The thickness of the enamel on upper and lower anterior teeth can be observed in . Figs. 6.11a–i and 6.12a–i. Therefore, the rotary instrument used for the preparation should have a diameter compatible with the enamel thickness of each area. In relation to the intensity of chromatic alterations, for mild ones, a 0.4-mm-deep preparation on enamel is done on the cervical third and 0.5 mm on the medium and incisal thirds. For teeth with more severe discoloration, a 0.5-mm-deep preparation on enamel could be performed on the cervical region and 0.7–1 mm on the medium and incisal thirds. Concerning the tooth’s shape, small or peg-­shaped teeth will require less removal of tooth structure to cover the surface with restorative material, aiming to obtain the necessary material thickness and good aesthetic results. In the same way, lingually inclined teeth may require minimum or no preparation of the labial surface.  

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In order to control the preparation depth and guarantee the ideal amount of tooth structure removal, two preparation guides (or reduction guides) can be produced with a putty viscosity silicone impression material. This technique is shown in . Fig.  17.1a–l. For taking the  trayless impression, a putty silicone base and catalyst are mixed uniformly before being placed by hand on the labial and lingual sur 

faces of the tooth that will be prepared and neighbour ones (. Fig.  17.1b). After setting, the first  impression is gently removed, and a new impression is taken. One of impressions will be cut perpendicularly to the long axis of the tooth, at the center of the crown, and on the mesiodistal direction (. Fig. 17.1c–i). The second one will be cut parallel to the long axis of the tooth, at the center of the crown on  

 

a

b

c

d

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..      Fig. 17.1  Preparation guides made with silicone impression material. a Two portions of heavy putty silicone must be used; b after mixing with the catalyst, it is applied over the teeth before preparation; c–f to see the amount of tooth structure removal on the mesiodistal direction, two parallel longitudinal cuts are performed on the first guide, on the area that corresponds to half of the crown of the adjacent teeth, followed by one perpendicular to the long axis of the

tooth to be prepared; g, h testing of the preparation guide. i evaluating the tooth structure removal after preparation; j to evaluate the amount of tooth structure removal on the cervicoincisal direction, the second guide must be cut at the region corresponding to the center of labial surface, parallel to the long axis of the prepared tooth; k testing of the guide; l evaluation of the structure removal after the preparation

671 Aesthetic Veneers: What Are They and How to Handle Them?

g

h

i

j

k

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17

..      Fig. 17.1 (continued)

the cervicoincisal direction (. Fig. 17.1j–l). Those preparation guides are placed over the tooth during the preparation procedure, to analyze if an adequate removal of the tooth structure is being performed.  

Tip

In order to control the preparation depth and guarantee the ideal amount of tooth structure removal, preparation guides can be produced with a putty viscosity silicone impression material.

The outline form of the veneer tooth preparation is determined by the surrounding structures, i.e., gingiva and neighbor teeth. Regarding the cervical cavosurface margin of the preparation, the height of the lip line during the maximum smile is important to determine its limit. In other words, it is important to know if the cervical tooth region will be visible or not during the smile. To obtain a completely hidden tooth-­ restoration interface, the margin of the preparation has to be placed inside the gingival crevice. However, any defect interfacial defect of the restoration may promote biofilm deposition in this area, leading to gingival inflammation, even though it might be mild. Thus, if the tooth-restoration inter-

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face is prepared close to or slightly before the gingival margin, it may contribute to the health of the surrounding soft tissues. However, this position of the margin can only be possible on patients that do not show gingival margin during maximum smile and present little or no color alteration of the tooth, or on the patients that do not mind having a less favorable aesthetics at this area, aiming to protect the gingival health. However, most people simply do not accept a visible margin, even if it cannot be noticed during conversation on the social life situations. On these cases and on the situations where the lip line shows the marginal gingiva, the cervical cavosurface angle of the preparation should be placed 0.1–0.3 mm inside the gingival sulcus. In relation to the proximal margins of the preparation, on teeth with slight color alterations, they should be placed before the proximal contacts. However, on teeth with intense discoloration, the preparation must  go further as half the contact area, in such a way that the dark background would not be visible after the restoration. When there are diastemas, the preparation should extend to the interproximal surfaces, allowing the correct restoration of the proximal contour. Another aspect regarding proximal limits of the preparation is the sight’s angle (or viewing perspective), when preparing the gingival embrasure areas, below the interproximal contact. When teeth are observed

from a perpendicular direction (sight’s angle of 90 degrees) in relation to the labial surface  – a position that dentists generally use to evaluate the final preparation – there is a poor vision of the gingival embrasure between contiguous teeth. This viewing perspective is called “static area of visibility” and does not represent the actual viewing perspective that the patient could be seen by other people in daily life. This may lead to insufficient preparation of some areas of the facial surface of the crown. On the other hand, when the tooth is observed from a lateral perspective, in a sight’s angle smaller than 90 degrees, the gingival embrasure areas become more noticeable. If this is not taken into consideration, the aesthetic outcome of the veneer restoration may not be pleasant, due to the remaining  of the discolored areas of the tooth uncovered by the veneer. The dentist viewing perspective during preparation needs to change constantly, to evaluate if the dark areas are not remaining unprepared and exposed, when the patient is observed from different angles. This active viewing perspective is called “dynamic area of visibility” and is necessary during the preparation (. Fig. 17.2a–d) [16, 23]. In relation to outline in the incisal edge, there are three possibilities. The type I (or window preparation) has a feathered edge, while the type II has an incisal reduction and a butt joint; and the type III (or wrap preparation) has an inci 

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..      Fig. 17.2  Lateral view perspective of the embrasure area changing the sight’s angle. a–c Preparation without considering the dynamic area of visibility. b, d preparation considering dynamic area of visibility

673 Aesthetic Veneers: What Are They and How to Handle Them?

sal reduction associated with a palatal chamfer [24]. For direct composite veneer restoration on teeth with thick incisal edges, the feathered-edge preparation should be chosen. However, on cases of patients with very thin incisal edges that are susceptible to fractures, or when teeth need to be elongated, as well for all indirect veneers, an overlapped incisal edge preparation with butt joint or a palatal chamfer should be performed. These preparations provide proper thickness of the ceramic at the margin to prevent restoration fracture, restrict the angle fractures, and enhance the aesthetics of the laminate (. Fig. 17.5). As in most clinical cases, the direct veneer preparation is restricted to enamel, and it usually does not lead to postoperative complications, from the pulpal or functional point of view. From the periodontal point of view, a correct cervical anatomy and the perfect fitting of the veneer to the preparation, at this region, avoid alterations of the periodontal tissues [18]. In some cases, veneers have shown to be a better choice than full crowns, in particular for patients with deep overbite, where there is usually not enough space on the lingual tooth surface; or for the mandibular anterior teeth, where it is easier to preserve the pulp integrity than on the full crown preparation.  

17.3 

When a homogeneous reduction of the labial surface is desired, the first step for the veneer preparation is to determine the maximum preparation depth, by making facial depth cuts with known dimensions (. Fig.  17.3a–o). The preparation is started with the peripheral depth cut following the gingival contour, in a U shape (. Fig.  17.3b–d), with a round diamond point, with a diameter compatible with the size of the tooth and depth of aimed preparation, following the contour of the gingival margin [11, 16]. By knowing the diameter of the diamond point, it is possible to standardize the depth of the preparation, by penetrating half of its diameter into the tooth surface. For instance, the No. 1011 diamond point has a 0.8 mm of diameter, while the No. 1012 one has a 1.0 mm of diameter, and the No. 1013 one has a 1.2 mm diameter. As mentioned above, for teeth with small color alteration, a 0.4 mm reduction should be planned on the cervical region, while for the ones with severe discoloration, this reduction should be 0.5 mm. For that, half of the diameter of the No. 1011 and No. 1012 burs, respectively, can be used as references [25]. During the preparation of the peripheral depth cut on the cervical area, it should be performed first  

 

a

b

c

d

..      Fig. 17.3  Direct veneer tooth preparation. a Initial aspect; b–e preparation of peripheral depth cut. f–i preparation of the cervicoincisal depth cut; j reduction of the mesial half of the labial surface; k analysis of the tooth structure reduction; l reduction of the

Sequence of Tooth Preparation

distal half and finishing of the preparation margin using a gingival protector instrument; m analysis of the preparation on the mesiodistal direction. n analysis of the preparation on the cervicoincisal direction; o finished preparation with supragingival margin

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e

f

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..      Fig. 17.3 (continued)

675 Aesthetic Veneers: What Are They and How to Handle Them?

m

n

o

..      Fig. 17.3 (continued)

before the gingival margin, even if later the gingival cavosurface margin will be placed inside the gingival sulcus. In doing so, subsequent corrections of the preparation can be performed without invasion of the biologic width. Next, the peripheral depth cut should be extended along the mesial and distal embrasures until the incisal edge (. Fig. 17.3e). This proximal extension of the preparation should be guided by aesthetics, reaching areas where the tooth/restoration interface could not be seen, taking into consideration the dynamic area of visibility (. Fig. 17.2a–d). The more compromised in terms of color alteration is the tooth structure, the larger the extension of the preparation toward the proximal surfaces should be  – which can even involve half of the proximal contacts. In this case, when performing the proximal reduction, the adjacent teeth should be protected with a steel strip. Next, a cervicoincisal depth cut should be prepared in the center of the labial surface with a No. 2135 tapered diamond point with a rounded tip, for teeth with slight discoloration, or with a No. 4138 point for darker teeth. However, to obtain a homogeneous reduction of the entire labial surface, the cervical-incisal depth cut should be prepared in three planes, following the convexity of the labial tooth surface (. Fig.  17.3f–i). This way, the reduction will be performed evenly over the tooth surface, allowing the application of a homogeneous thickness of the restorative material over the prepared area.  

 

 

The following step is to connect the peripheral depth cut to the cervicoincisal one, first on one-half of the tooth surface, following the mesiodistal contour of the surface (. Fig.  17.3j, k). Then, the reduction should be performed on the other side (. Fig. 17.3l). The depth and homogeneity of the reduction can be evaluated with the preparation guides (. Fig.  17.3m, n). Then, the improvement of the preparation margins can be performed, placing the gingival margin 0.2 mm inside the gingival sulcus, if there is an aesthetic issue. Such procedure can be done using a No. 2135 tapered diamond point, for a chamfer finish line [16]. The gingival tissue can be protected from the rotary instrument using a metallic gingival retraction/protection instrument (. Fig. 17.3l). Another option to control the depth of the facial reduction is to use depth-limiting diamond points, available in two different diameters. The No. 4141 three-wheeled diamond depth cutter creates mesiodistal depth of cuts 0.3  mm deep, while the No. 4142 performs depth cuts of 0.4 mm deep (. Fig. 17.4a). Between the wheels covered by diamonds, there are inactive areas, which will touch the intact tooth structure and control the tooth removal. Even when the depth-­limiting diamond points are applied, the previous peripheral depth of cut can be performed first, to facilitate the preparation (. Fig.  17.4b). Then, the depthlimiting diamond point is to be used, followed by the  

 

 

 

 

 

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a

b

c

d

e

f

17 ..      Fig. 17.4  Preparation using depth-limiting diamond point. a Three-wheeled diamond depth cutter points with different diameters; b peripheral depth cut; c, d mesiodistal depth cuts prepared

with No. 4141 point; e connection of all depth cuts to create a homogeneous enamel reduction; f finished preparation with intrasulcular gingival margin

No. 2135 tapered point to connect to the peripheral depth of cut (. Fig. 17.4c–f). For indirect veneers, overlapped incisal edge preparation needs to be performed to avoid fractures of the restoration. That can be done by a butt joint (. Fig.  17.5e, f) or a wrap preparation (. Fig. 17.5i, k). In the first case, just an incisal reduction is performed, while on the latter, it is followed by an additional palatal chamfer. There is a discussion in the literature about which would be the best design for the incisal edge of ceramic veneer preparations [24]. However, the palatal chamfer effectively counteracts shear stress in the incisal

area, due to inter-incisor contacts during protrusive movement of the mandible, allowing a safe incisal disocclusion guide. This design also provides a definite seat during cementation [26]. Before preparing the palatal chamfer, an incisal reduction of about 1  mm must be done. For that, three incisal depth cuts are performed by placing a No. 2135 diamond point perpendicular to the long axis of the tooth (. Fig. 17.5c). They are then connected, as shown in . Fig.  17.5d–f. Then, a 0.5–1-mm-­ long palatal chamfer is prepared. The palatal depth of cuts is done with the No. 2135 diamond point posi-

 

 

 

 

 

677 Aesthetic Veneers: What Are They and How to Handle Them?

a

b

c

d

e

f

g

h

..      Fig. 17.5  Overlapped incisal edge preparation with a palatal chamfer. a, b Preparation restricted to the labial surface; c incisal depths of cuts; d–f incisal reduction; g, h palatal depth of cuts. i–l palatal chamfer concluded

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i

j

k

l

..      Fig. 17.5 (continued)

tioned parallel to the long axis of the tooth, which are then connected to one another, including the proximal surfaces (. Figs. 17.5g–l and 17.7c).  

Tip

17

It is important to familiarize oneself with the detailed steps in tooth preparation. One needs to have a clear anatomical picture of teeth in mind during the preparation. Selection of appropriate burs or points is vital for the success of tooth preparation, because it is a matter of tenths of millimeters.

17.4 

Direct Veneer Restoration

To restore the labial surfaces of teeth after veneer preparations, a resin composite material with excellent polishing characteristics should be selected. Those recommended include microhybrid, nanohybrid, and nanoparticle composites, to recover the dental aesthetics. Before performing the final veneer, a restoration mock-up can be done, using the same composite, shades, and thickness layers of the final restoration. The materials should be applied over the teeth without any previous adhesive treatment. After ­ curing, the

restoration mock-up is evaluated, and if it is not the one desired, it can be easily removed by pulling out the veneer by its margin, with the aid of an exploratory probe. Then a new composite mock-up can be placed and evaluated. This will also allow the dentist to evaluate whether the depth of the preparation performed, when associated to characterization material and composites, is enough to hide any altered background color the tooth may present. If necessary, a deeper preparation can still be done. Isolation of the operating field can be performed with gingival retraction cord and cotton rolls, or with a rubber dam associated with clamps to expose the margin of the preparation. In those cases, the No. 210 or 211 clamps present the ideal shape, allowing adequate displacement of the gingival tissue. If the preparation is restricted to enamel, after acid etching (with phosphoric acid gel) and rinsing, the surface can be dried with air stream, resulting in a  opaque chalky-white appearance. In this case, if the dentist is using an adhesive system with separate primer and bonding bottles, the primer does not need to be applied. However, if there are areas of exposed dentin on the prepared surface, after rinsing the acid gel, the surface should be blot dried. This will leave the surface visibly moist (glossy), followed by an application of a primer/bond adhesive system or a single bottle adhesive system. Due to the abundant enamel availability on this kind of preparation, the acid etching technique should

679 Aesthetic Veneers: What Are They and How to Handle Them?

be preferred in relation to the self-etching approach, resulting in higher bond strength values. In the case of heavily discolored teeth or when there are several shades on tooth surface after preparation, due to several previous restorations, a thin layer of opaque light-curing viscous liquid characterization material, also known as color modifier, tint, or masking agent, can be used to create a whiter homogeneous surface color. Either white or VITA™ shade opaque characterization materials can be used. After that, a thin layer of dentin shade composite should be used,

to mask the intense opacity of the tint, followed by a final layer of more translucent enamel shade composite, to reproduce enamel characteristics (. Fig. 17.6a–o). If the adjacent tooth has a labial surface rich on macro and micro textures, they should be reproduced over the restoration according to what was described in 7 Chap. 14. When the tooth that will receive the veneer has Class III or IV restorations that require replacement, this should be made on a previous dental appointment. This would simplify the veneer preparation procedure.  

 

a

b

c

d

e

f

..      Fig. 17.6  Direct veneer restoration. a Tooth-shade evaluation; b, c application of gingival retraction cord size No. 000; d protection of neighbor teeth with a Mylar strip and acid etching. e, f application of the adhesive system; g light-curing; h, i application of opaque

light-curing color modifier shade A1 (Kolor + Plus – Kerr); j application of dentin shade composite layer (Z350, 3 M/Espe); k, l application of enamel opacity composite. m enamel shade composite applied; n, o final result

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g

h

i

j

k

l

m

n

17

..      Fig. 17.6 (continued)

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o

17.5 

17

Indirect Veneers

The indirect veneers can be performed with composites or ceramics. As the restoration is prepared outside the mouth, an impression or scanning of the preparation is necessary, in order to create the restoration over a cast or milling it in CAD/CAM machine. Before luting, a pretreatment of the restoration is required, to improve its bonding to the tooth structure. Those procedures are presented in the following sentences. 17.5.1  ..      Fig. 17.6 (continued)

When the teeth present only chromatic alteration and the labial shape is intact, a custom-made matrix can be created before the tooth preparation, copying the surface shape and texture. It can be used later to restore the exact original anatomy, thus saving clinical time [16]. That matrix can be created in two different ways. In the first, an impression can be taken, and a plaster model obtained on a previous dental visit. Over the model a matrix can be produced using a thermoplastic material, such as low-density polyethylene sheet, and a vacuum thermoforming machine. It follows the same technique applied to produce dental bleaching trays. Another possibility is to create the matrix immediately before the preparation, using self-curing acrylic resin. In this case, after application of a retraction cord into the gingival sulcus, a thin film of liquid petroleum jelly is applied over the tooth surface, followed by the placement of acrylic resin, picking up powder particles on wet brush, and applying over the surface. It must be applied over the labial surface of the treated tooth, incisal edge, and part of the labial surface of the adjacent teeth. A handle made of acrylic is created over the external surface of the acrylic matrix to simplify its placement. After curing, the margins of the matrix need to be finished with an abrasive mounted stone. The acrylic matrix should be tested in the position before and after the operating field isolation. After the preparation, adhesive procedures are performed, and the dentin shade composite applied. Before light-curing of each resin composite layer, the matrix should be placed in the position to evaluate if there still is space left to apply the enamel shade composite. The matrix must be isolated internally with liquid petroleum jelly. The enamel shade composite is then placed inside the matrix and taken in the position. The excess of material is removed, and the restoration is light-cured for only 10 s. The matrix is removed, and the finishing of the margins should be performed with a scalpel blade, followed by the final light-curing. The labial surface of the restoration will have the same shape of the natural tooth, and just a polishing will be generally necessary.

Dental Ceramics

Ceramic is defined as something made from nonmetallic material by firing at high temperature. The dental ceramics are widely used biomaterials in prosthetic dentistry, because of their attractive and well-studied clinical properties. They have basically three indications in dentistry: (a) ceramic-­ metal crowns (porcelain fused to metal, PFM) and fixed partial dentures; (b) all-ceramic restorations consisting of crowns, inlays, onlays, indirect laminates (veneers), and short-span anterior bridges; and (c) ceramic denture teeth. Ceramics for dentistry are aesthetically pleasing by their color, shade, and luster and are chemically stable. A dental ceramic is best described as a complex multiphase system. It comprises a dispersed crystalline phase which is surrounded by a glassy phase, actually a continuous amorphous phase. The crystalline phase is mainly responsible for its physical properties, while the glassy phase gives its aesthetic characteristics. Traditional feldspar-based ceramics are also referred to as “porcelain.” They are silicon (Si) based and made of aluminosilicate minerals, such as quartz (SiO2), feldspar (KAlSi3O8–NaAlSi3O8–CaAl2Si2O8), and kaolin (Al2Si2O5(OH)4). Typically, dental porcelain is composed of ca. 73–75% feldspar and ca. 22–25% quartz. To increase the workability of the unfired porcelain, and to impart X-ray contrast, some kaolin needs to be added. Pigments are important to provide the required aesthetic shade and hue [4]. It is noteworthy that there is a crucial difference between a regular ceramic (such as your coffee mug) and a dental porcelain, which is related to the proportion of quartz, feldspar, and silica (SiO2) contained in the ceramic matrix. Dental porcelains (feldspathic-, leucite-, or fluorapatite-based) can meet the highest aesthetic standards but have limitations: they are brittle, with low fracture toughness and flexural strength. This is a consequence of their very high glass content. Due to the limited thickness in indirect laminates and the material’s properties, the clinical success of porcelain veneers relies on reinforcement of the restorations by adhesive cementation [27]. The new glass ceramics have improved mechanical properties due to a higher proportion of the crystalline phase that strengthen the material [4]. As they possess higher fracture strength and increased toughness, when compared to the

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porcelain, they also have a wider application field. To the group of glass ceramics belong the leucite-­based and lithium disilicate-based (LiSi2O5) ceramics, as well the new zirconia-­ reinforced glass ceramic [27]. The stronger materials available are the so-called high crystalline ceramics, mainly the Y-TZP zirconia-­ based ones. However, most are highly opaque and have low aesthetics, not being generally recommended for indirect veneers. >> Identifying various dental ceramics and their correct indications will guarantee success to the dental treatment. One should never underestimate the significance of etching, not only of the tooth structure but also of the ceramic. In cementation it is vital to carefully adhere to the luting protocol.

17.5.2 

17

Impression/Scanning of the Tooth Preparation

The first step to obtain a proper impression is to perform the gingival displacement. For that, a retraction cord is gently placed inside the sulcus using a retraction cord packer. The cord must be placed beneath the finishing line to avoid interferences during the impression, for capturing the details of the gingival cavosurface margin. After that a low viscosity elastomeric impression material (addition silicones and polyethers) is applied over the preparation, followed by the putty material previously loaded inside an impression tray. The retraction cord can be left in place during impressioning, being generally removed in the mold. The gingival displacement can also be performed with the double-­cord technique. A thin retraction cord (000) embedded in hemostatic solution is placed inside the gingival sulcus, and over it a thicker one (00). The one step putty-wash silicone impression technique can be used. For that, immediately before the impression, the thicker cord is removed, and the low viscosity material injected around the tooth preparation. The putty impression material is mixed, applied inside metal trays and immediately placed intraorally, letting the materials to polymerize simultaneously. A high-accuracy type IV dental stone is poured into the mold. After its hardening, a replica is obtained, which is positive reproduction of the soft tissues and teeth. The cast is then sent to the dental technician to prepare the laminate. Another option is to perform a 3D digital impression, scanning the tooth preparation using an optical intraoral scanner. The information is digitalized, and a virtual 3D model is created. A dedicated software is used for restoration design process. The milling unit is used to mill the laminated from ceramic or composite blocks.

17.5.3 

Provisional Restoration

Some indirect restorations are performed chairside, such as when a CAD/CAM system is available in the dental office.

However, when the final restoration will be prepared by an external laboratory, an interim restoration will be required. When a single tooth will receive the provisional restoration, a plastic clear crown form (. Fig. 8.13a) can be used as a matrix to restore the external anatomy of the tooth. The crown form is placed on the tooth and the excess is trimmed. A direct composite or a bis-acryl composite is applied inside the form, which is taken in position. The excess is removed with a sable brush or disposable applicator moistened with bonding agent. After light-curing the matrix is removed, while the composite stays in place. The margins are checked, and any excess can be removed with a scalpel blade. Generally, the temporary restoration remains in place without any adhesive application, solely through mechanical retention. The occlusion can be adjusted with diamond finishing points. Any adjustments of the interim restoration must not change the previous tooth preparation. If the restoration dislodges, a temporary aesthetic cement can be used (e.g., Bifix Temp, Voco; ClearTemp LC, Ultradent). Another option is to etch a 1 mm diameter area on the center of the preparation and cement the temporary restoration with a flowable composite [21]. When the original labial surface has appropriate shape, and the veneer indication is only related to color alteration, a matrix can be prepared with a putty silicone material inside the mouth, previously the tooth preparation. A trayless impression is performed, by applying the material covering the labial and lingual surface of the anterior and some posterior teeth. Interproximal slits are cut on the buccal areas of the matrix, which serve as vents through which the excess of the provisional material will flow. An appropriate amount of the bis-acryl composite is applied in the matrix, which is taken in place until the initial cure of the material. The marginal fit is analyzed, and finishing is performed. If the restoration is dislodged, it can be cemented as described above. When the teeth shape will be changed by the veneers, a diagnostic waxup can be used to prepare the silicone matrix, which will guide the production of the temporary veneers. The patient should always be informed about the low retention and fragile characteristics of the provisional restoration [21].  

17.5.4 

 xtraoral Phase for Indirect E Restoration

In modern dental laboratories, the ceramic veneers may be prepared using various approaches. The first and oldest method is the sintering, which consists in application of an aqueous slurry of ceramic particles on a refractory cast. A sintering is performed over the cast at a temperature above the softening points of the ceramic, whereby the matrix particles melt and the particles coalesce [28]. Different layers of ceramics, of different shades and opacities, are incrementally applied, creating a polychromatic and natural look for the final restoration. This method is used for feldspar and leucite-­ reinforced veneers [21, 28]. A second option is the direct casting or hot-pressing. In this case a waxing of the restoration is performed that is

683 Aesthetic Veneers: What Are They and How to Handle Them?

embedded in a refractory material. The lost wax technique is thickness and high translucency of the laminates, an incorapplied, creating a refractory mold. In this case a ceramic rect selection of the cement shade  can jeopardize the aesingot is softened by heating and can be pressed or injected thetic outcome of the whole treatment. The try-in paste is into the mold, creating monolithic and monochromatic lam- applied in the internal side of the restoration, which is placed inate. It can be used for lithium disilicate glass ceramic and in position like will be performed during the final luting. The leucite-containing glass ceramic [21, 28]. test should start with an untinted and transparent try-in The last method is based on the use of a CAD/CAM sys- paste. If the first shade is not adequate, the laminate and the tem. In this case an intraoral scanning or a scanning of a preparation are washed, and a new shade is tested, until stone model is performed, creating a virtual cast of the teeth. defining the correct one for that clinical case. Different The restoration design is done in the dedicated software, and options of cements/try-in pastes shades are available, e.g., the milling is performed on a ceramic bloc, also creating transparent, opaque white, bleach, yellow, brown, or followmonolithic and monochromatic laminates [21, 28]. The mill- ing the Vita Classical shade guide. After that, the dentist must ing can take place chairside or in the dental laboratory. This thoroughly remove the try-in paste with water spray and dry method can be applied for ceramic blocs made of feldspar the restoration with water- and oil-free air. No occlusal evaland leucite or lithium disilicate-reinforced glass ceramics, uation should be performed before the cementation, to prezirconia-reinforced glass ceramic, and hybrid dental ceramic vent unforeseen fracture of the fragile laminate [21]. (ceramic network structure reinforced by a polymer network). Recently high-translucent zirconia has been proposed for veneer restoration, although not providing yet the best 17.5.6  Pretreatment of Veneers aesthetic outcome in relation to the other options [29]. Feldspar and leucite are milled from fully sintered blocs. The Obviously, tooth tissues do not possess any natural affinity to restoration is polished or glazed in a small ceramic furnace. dental ceramics. This explains why pretreatment of tooth tisLithium disilicate glass ceramic, zirconia-reinforced glass sues and a ceramic restoration, in association with adhesive ceramic, and Y-TZP monolithic zirconia are milled from system and a resin cement, are vital. Veneers as well other oversized dimension from partly sintered blocs (precrystal- dental indirect restorations require a surface pretreatment lized state). That initial lower strength allows the milling pro- for durable adhesion. This step is also called surface condicess. They are then fully sintered in a furnace, shrinking to tioning. It is defined as one or a series of steps, including (but the required size, reaching its final translucency and maxi- not limited to) cleansing, removal of debris, and modificamum flexural strength. The restoration with hybrid ceramic, tion of internal restoration surface, over which a silane coulike a composite block, is just milled and polished. pling agent and adhesive will be applied, chemically bonding A monolithic restoration means that the final shape of the to the resinous cement [3, 8, 31]. restoration was obtained with a single material, which lacks The surface treatment will prevent the formation of (or the polychromatic characteristic of a natural tooth, such as remove) any weak surface layer on the substrate (debris, the translucent incisal edge, opalescence, counter-­ grease, oil, contaminants). That will increase the surface free opalescence, and defined dentin mamelons [30]. Those are energy and maximize the molecular interaction at the interobtained when the hot-pressing and CAD/CAM methods facial layer, between the laminate and resin cement, optimizare employed. In this case the restoration can be character- ing the adhesion at the interface. It can also create special ized either externally, through glazing (staining), or alterna- surface micro-features for micromechanical retention [7, tively cut-back and covered with layers of compatible sintered 31]. Sufficient adhesive strength can be provided and mainceramic [28]. tain a long service time. Porcelains and the new glass dental ceramics are pretreated by acid etching using hydrofluoric acid, which is a 17.5.5  Try-in Procedure very corrosive and toxic agent. Great caution and care must be exercised when using it. Acid etching is considered the Each laminated must be tested into the preparation for fitting. most effective procedure in enhancing adhesion between For that the provisional restoration is removed with an instru- feldspar-based and glass ceramic laminates and resin cement. ment. The preparation is cleaned with pumice and a prophy- By etching the ceramic surface, a partial dissolution of the laxis rubber cup or brush, followed by washing and drying. ceramic glass content occurs, creating a porous topography Any residues of temporary cement must be removed that produces micromechanical retention between the lami(. Fig. 17.7c). The internal area of the laminate is moistened nate surface and resin cement (. Fig.  17.7g, h) [32]. Acid with water or glycerin and the restoration is placed. Inadequate etching is normally performed using ca. 5–10% gel-like seating can be diagnosed by using a low viscosity silicone hydrofluoric acid. Nowadays, the use of that acid etching is material (Fit Test C & B, Voco). The internal adjustments can unanimously recommended [27]. For lithium disilicate and be performed with small round fine diamond points. zirconia-­reinforced glass ceramic veneers, a 5% hydrofluoric To verify the shade of the restoration, water-soluble try-in acid is applied for 20 seconds. For leucite-reinforced glass pastes that simulate the optical characteristics of the resin ceramic and feldspar ceramic restorations, the recommended cements can be used to select its color. Due to the small etching time is around 60 seconds.  

 

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A mandatory application of a silane coupling agent is needed to chemically bond the inorganic material (silica) of ceramic structure to the resinous monomers in the adhesive system and resin cement. The silane also allows the resin to better wet the ceramic surface that may easily penetrate into the porous structure [32, 33]. After silane solution dries for

around 1 minute, the adhesive and resin cement can be applied for final cementation of laminate (. Fig. 17.7i) [7, 8, 31, 34, 35]. Some manufactures recommend the application of the adhesive over the silanized surface, which is not light-cured before the cementation (. Fig.  17.7j). Others recommend the application of the cement directly over the  

 

a

b

c

d

e

f

17

..      Fig. 17.7  Indirect veneer restoration. a Color alteration on nonvitalized central incisors; b internal and external dental bleaching procedure did not significantly improve the aesthetics of the smile. The initial uneven gingival zenith position of the right central incisor in relation to the left incisor was corrected by a gingival surgery; c preparations with incisal reduction and palatal chamfer; d placement of a retraction cord into the crevice, protection of the neighbor teeth

with a clear strip and acid etching; e application of the adhesive system; f glass ceramic veneers etching of the internal surface with hydrofluoric acid gel; h etched surface after washing and drying, showing a frosty appearance due to the surface roughness created by the dissolution of the glassy phase. i application of the silane coupling agent; j application of the adhesive system; k luting of the veneers with a light-curing resin cement; l final result

685 Aesthetic Veneers: What Are They and How to Handle Them?

g

h

i

j

k

l

..      Fig. 17.7 (continued)

silanized surface. Each manufacturer instruction must be followed. For indirect composite veneers, the internal surface of the restoration must receive sandblasting (air abrasion). This procedure increases the surface roughness to provide micromechanical retention. After that the surface is cleaned with spray of air/water or ultrasonic bath. Some manufacturers recommend the application of silane to promote bonding to the inorganic matrix of the composite, exposed by the sandblasting procedure.

Tip

Understanding the various steps and rationale in ceramic veneer pretreatment is important. The try-in must be performed before the acid etching. After etching the internal must not be contaminated. If any contamination occurs, the surface needs to be cleansed with acetone or ethanol or re-etched with phosphoric acid, followed by rinsing with water.

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17.5.7 

Cementation of Indirect Veneers

The rubber dam isolation can be performed, in association with clamps for anterior teeth, although it is not always feasible or possible [27]. Another possibility is to apply a lip and check retractor to create a soft tissue displacement. The neighbor teeth surfaces are protected with a clear mylar strip or a polytetrafluorethylene (PTFE) tape (. Fig.  17.7d). The tooth preparation surface is etched with phosphoric acid gel for 15 second (. Fig. 17.7d). If no dentin was exposed during the preparation, the surface is completely air dried, leaving a frosty-white appearance. However, if any dentin was prepared, the blot drying technique is used, and the excess of moisture is removed with a cotton pellet, leaving a visible moistened surface. The selected adhesive system is applied, and the excess is removed with air stream (. Fig. 17.7e). No light-curing is performed. The internal area of the restoration is etched with hydrofluoric acid, and the silane coupling agent is applied, as previously described. According to the manufacturer’s instruction, the adhesive system can be applied over the silanized surface (. Fig. 17.7j). The excess is removed with an air stream, but no light-curing is performed. The resin cement of choice is the light-curing one, which allows a better color stability over time. The veneers are held with a placement instrument that features a flexible adhesive tip (OptraStick, Ivoclar Vivadent), charged with the resin cement on the internal surface and then positioned with continuous digital pressure in the tooth. Excess of cement can be removed with a brush. The proximal area can be cleaned with dental floss. A light-curing is performed for 10 seconds, to ensure the positioning and fitting of the laminate. After the cementation of the last restoration, a layer of glycerin gel is placed over the interphase between tooth and restoration, to eliminate the oxygen inhibition layer of the cement, and the light-curing is performed again for 60 second on every side of the tooth. Any additional excess can be removed with a No.11 scalpel blade. In the interproximal area, a serrated separating strip can be employed (. Fig. 15.18f) [21]. If more than one restoration will be cemented, the clinician must try in the restoration that will be luted next, because even small excess of cement from the previous laminate will prevent the seating of the subsequent. The laminates of  both central incisors are simultaneously cemented, i.e. both laminates are place in position first an then light-curing is done simultaneously,  following by  the cementation on  those teeth  more distally  located. If any error occurs, they will be located far from the midline and will be less visible [21].  

 

 

17.5.8 

Finishing and Polishing

After cementation, the dynamic occlusion contacts must be evaluated with a thin articulating paper. The anterior disocclusion guide must occur without excessive stress concentration in just one tooth. The canine disocclusion guide must also be evaluated. Any adjustment can be performed with a fine-grit diamond points or 30-flutted carbide bur. The finished areas must be properly polished using abrasive rubbers, disks, or polishing pastes with felt disks, using progressively finer abrasives (. Figs. 4.29a–d and 4.31b). The whole margin must be evaluated with an exploratory probe. Any excess must be removed using a very thin grit needle shaped diamond point. Any excess in the interproximal area  must be detected with dental floss and removed with abrasive strips. The margins of the restorations should be reevaluated in the next dental appointment to detect any remaining discrepancy [21].  

17.6 

Changes of the Apparent Tooth Dimension by Optical Illusions

 

17

 

In some patients, changes in the clinical width or length of a certain teeth are desired for aesthetic improvement. For that, orthodontic treatment or gingival surgery is usually required. However, some patients might not desire to receive such an invasive or prolonged treatment. For those cases, some superficial morphology changes can be performed on the labial surface, making the tooth look larger or shorter, thereby creating an optical (and aesthetic) illusion. The art of creating illusions consists of changing perceptions, causing an object to appear different from what it actually is. This is performed by changing the so-called tooth face, which is a flat area on the labial surface [36]. In the same way, the size of incisal and cervical embrasures determines the youth aspect of teeth and can be shaped when making the restoration. 17.6.1 

Flat Area

On the mesiodistal direction, the flat area or tooth face is placed between the mesial and distal transitional line angles (. Fig.  17.8a, c). The transitional line angles on the labial surface of neighboring teeth form the labial embrasures. Even though it may not be a perfectly flat surface, it is responsible for reflecting the visible light and for the apparent dimensions of the anterior teeth [16]. Light that reaches the facial surface between the transitional line angles is reflected to the observer, while the mesial and distal areas to  

17

687 Aesthetic Veneers: What Are They and How to Handle Them?

a

b

c

..      Fig. 17.8  Location of the flat area (tooth face) on the labial surface of the central incisor. a On the mesiodistal direction, it is located between the mesiolabial and distolabial transitional line angles. On the cervicoincisal direction, it is located between the high of curvature and

the transition line between the middle and incisal third of the crown; b delimitation of the flat area from a proximal view; c delimitation of the flat area from an incisal view

those line angles deflect the light, making them appear darker and less observable and seen. Reallocating the position of the transitional line angles, the area that reflects light can be increased or reduced [36]. The more the transitional line angles approach the center of the labial surface, the narrower this flat area becomes. On the other hand, the more displaced toward the proximal surfaces these transitional line angles are, the wider is the flat area. The increase of the flat area width, on the mesiodistal direction, gives a widening illusion to the tooth. Given that, teeth with the same actual anatomical width can have different apparent dimension if they have different width of the flat areas [16]. That concept is described as the “law of the face,” [21] which implies making dissimilar teeth appear similar by turning the apparent faces equal. . Figure 17.9a–d shows resin composite replicas obtained from the natural tooth shown in . Fig.  17.8a–c, where the width of the flat area was reduced to create a narrowing illu-

sion. The changes that were planned are seen in . Fig. 17.9a and performed in . Fig.  17.9b, c. . Figure  17.9d shows the result after polishing. When performing a direct veneer restoration, the flat area can be adapted according to the individual needs, either during the application of composite increments or during the finishing procedures. To reduce the width of the flat area and create a narrowing illusion, the dentist should enlarge the mesial and distal embrasures, using a small diameter abrasive bur disk [16] On the cervicoincisal direction, the labial surface of anterior teeth generally has three inclinations. The flat area is then defined by those inclinations, located at the medium third of the crown, above the high of curvature, and below the transition line between the middle and incisal third (. Fig. 17.8a, b). The larger the flat area on the cervicoincisal direction, the larger will be the apparent height of the tooth. . Figure  17.10a–d shows composite replicas obtained from the natural tooth, originally shown in . Fig.  17.8a–c. The

 

 

 

 

 

 

 

 

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a

b

c

d

..      Fig. 17.9  Effects of flat area width on the apparent width of the crown using resin replicas of the same tooth. a Delimitation of the actual width of the flat area on the left and drawing of the new dimension on the right; b changing the position of the transitional line

changes were planned in . Fig.  17.10a and performed in . Fig. 17.10b, c through the cervical and incisal reduction of the flat central area, using an abrasive disk. Finally, in . Fig. 17.10d is shown the result after polishing. Based on the above presented explanations, to increase the apparent height of short teeth restored with veneers, the flat area should be enlarged in the cervicoincisal direction and reduced in the mesiodistal direction. Conversely, to reduce the apparent length of long teeth, the flat area should be reduced on the cervicoincisal direction and increased on the mesiodistal direction.

angles by wearing with abrasive disk; c transverse cross section showing the changes performed; d original aspect of the light reflection on the left and after changes on the right, creating a narrowing illusion

Tip

 

 

To reduce the apparent length of long teeth, the flat area should be reduced on the cervicoincisal direction and increased on the mesiodistal direction.

 

17

17.6.2 

Embrasures

The size and distribution of the embrasures directly influence smile aesthetic according to what was described in 7 Chap. 1 (. Fig. 1.11a–d). Therefore, when making veneer restorations on several teeth, dentists can change the embrasures to make the smile look younger. Changes in embrasure shape can be performed at the moment of the composite application or during the finishing of the restoration, using scalpel blades and thin polishing disks with small diameter [16]. Small or absent embrasures make the smile look older.  

Tip

To increase the apparent height of short teeth restored with veneers, the flat area should be enlarged in the cervicoincisal direction and reduced in the mesiodistal direction.

 

689 Aesthetic Veneers: What Are They and How to Handle Them?

a

b

c

d

..      Fig. 17.10  Effects of flat area length on the apparent height of the crown using resin replicas of the same tooth. a Delimitation of the actual flat area length on the left and drawing of the new dimension on the right; b length reduction with abrasive disk; c longitudinal cross

section showing the change performed; d original aspect of the light reflection on the left and changes on the right, resulting in the shortening of the apparent crown height

Conclusion

References

Aesthetic treatment decisions should be based on prevailing clinical conditions and the patient preferences and anticipations, following the principles of maximum conservation of the tooth structure. The veneers are restorations restricted to the labial surface of aesthetically compromised anterior teeth, on areas visible during smile or conversation, keeping intact the proximal and lingual surfaces. The restoration can be performed directly with composite or indirectly with a ceramic or composite. The indirect technique requires the impression or scanning of the preparation and a provisional restoration. The cementation steps are critical to the quality of the treatment, and a careful procedure must be performed. The clinical success depends on durable bonding between the laminate and prepared and primed tooth substance. Whatever is the choice of veneering material, the adhesive resin cement, and surface pretreatment methods, it is very important for the dentist to gain confidence with the use of the chosen laminate treatment modality.

1. Busato ALS, Hernandez PAG, Macedo RP.  Dentística: restaurações estéticas. 1st ed. Artes Médicas: São Paulo; 2002. 2. Kina S, Bruguera A.  Invisível. Restaurações Estéticas Cerâmicas. Artes Médicas: São Paulo; 2008. 3. Rufenacht CR.  Fundamentals of esthetics. Chicago: Quintessence Publishing; 1992. 4. Ho GW, Matinlinna JP. Insights on ceramics as dental materials. Part I: ceramic material types in dentistry. SILICON. 2011;3:109–15. https://doi.org/10.1007/s12633-011-9078-7. 5. Lung C, Matinlinna J. Silanes for adhesion promotion and surface modification. In: Moriguchi K, Utagawa S, editors. Silanes chemistry, applications and performance. New York: Nova Publishers; 2013. p. 87–109. 6. Palin W, Ferracane J.  Resin-based cements used in dentistry. In: Matinlinna J, editor. Handbook oral biomater. Singapore: Pan Stanford Publishing; 2014. p. 213–54. 7. Matinlinna J. Processing and bonding of dental ceramics. In: Vallittu P, editor. Non-metallic biomater tooth repair replace. Cambridge: Woodhead Publishers; 2013. p. 129–60. 8. Matinlinna JP, Lung CYK, Tsoi JKH.  Silane adhesion mechanism in dental applications and surface treatments: a review. Dent Mater. 2018;34:13–28. https://doi.org/10.1016/j.dental.2017.09.002.

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9. Ekambaram M, Yiu CKY, Matinlinna JP.  An overview of solvents in resin–dentin bonding. Int J Adhes Adhes. 2015;57:22–33. https:// doi.org/10.1016/j.ijadhadh.2014.09.007. 10. Ekambaram M, Yiu CKY, Matinlinna JP, King NM, Tay FR. Adjunctive application of chlorhexidine and ethanol-wet bonding on durability of bonds to sound and caries-affected dentine. J Dent. 2014;42:709–19. https://doi.org/10.1016/j.jdent.2014.04.001. 11. Araujo MA. Estética Para o Clínico Geral. Artes Médicas: São Paulo; 2005. 12. Touati B, Myara P, Nathanson D. Esthetic dentistry and ceramic restorations. London: Martin Dunitz; 1999. 13. Gaber DA. Porcelain laminate veneers. Chicago: Quintessence; 1988. 14. Mustafa A, Matinlinna J. Materials in dentistry. In: Matinlinna J, editor. Handbook oral biomater. Singapore: Pan Stanford Publishing; 2014. p. 81–154. 15. Nakabayashi N, Pashley D.  Hybridization of dental hard tissues. Tokyo: Quintessences Publisching Co; 1998. 16. Baratieri LN, Monteiro Junior S, Andrada MA, Ritter AV.  Odontologia Restauradora: Fundamentos e Possibilidades. Santos: São Paulo; 2001. 17. Henostroza GH.  Adesão em Odontologia Restauradora. Curitiba: Editora Maio; 2003. 18. Baratieri LN.  Dentistica: Procedimentos Preventivos e Restaura dores. Santos: São Paulo; 1993. 19. Felippe LA, Baratieri LN.  Direct resin composite veneers: masking the dark prepared enamel surface. Quintessence Int (Berl). 2000;31:557–62. 20. Neto NG, Carvalho RC, Russo EM, Sobral MA, Luz MA. Dentística Restauradora: Restaurações diretas. Santos: São Paulo; 2003. 21. Aschheim KW. Esthetic dentistry: a clinical approach to techniques and materials. 3rd ed. Saint Louis: Elsevier; 2014. 22. Durán Ojeda G, Henríquez Gutiérrez I, Guzmán Marusic Á, Báez Rosales A, Tisi Lanchares JP. A step-by-step conservative approach for CAD-CAM laminate veneers. Case Rep Dent. 2017;2017:1–6. https://doi.org/10.1155/2017/3801419. 23. Aschheim KW, Dale BG.  Esthetic dentistry: a clinical approach to techniques and materials. Philadelphia: Lea & Fabriger; 1993. 24. Chai SY, Bennani V, Aarts JM, Lyons K. Incisal preparation design for ceramic veneers. J Am Dent Assoc. 2018;149:25–37. https://doi. org/10.1016/j.adaj.2017.08.031.

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25. Pagani C, Silva EG, Rocha DM. Tooth preparations - Science & Art. Great Britain: Quintessence Publishing; 2017. 26. Jankar AS, Kale Y, Kangane S, Ambekar A, Sinha M, Chaware S. Comparative evaluation of fracture resistance of ceramic veneer with three different incisal design preparations – an in-vitro study. J Int Oral hHealth. 2014;6:48–54. 27. Benetti A, Papia E, Matinlinna J. Bonding ceramic restorations. Nor Tann Tid. 2019;129:30–6. 28. Wassell R, Nohl F, Steele J, Walls A. Extra-coronal restorations. Cham: Springer International Publishing; 2019. https://doi.org/10.1007/9783-319-79093-0. 29. Souza R, Barbosa F, Araújo G, Miyashita E, Bottino M, Melo R, et al. Ultrathin monolithic zirconia veneers: reality or future? Report of a clinical case and one-year follow-up. Oper Dent. 2018;43:3–11. https://doi.org/10.2341/16-350-T. 30. Della Bona A, Nogueira AD, Pecho OE. Optical properties of CAD– CAM ceramic systems. J Dent. 2014;42:1202–9. https://doi. org/10.1016/j.jdent.2014.07.005. 31. Lung C, Matinlinna J. Surface pretreatment methods and silanization. In: Matinlinna J, editor. Handbook oral biomater. Singapore: Pan Stanford Publishing; 2014. p. 359–98. 32. Ho GW, Matinlinna JP. Insights on ceramics as dental materials. Part II: chemical surface treatments. SILICON. 2011;3:117–23. https://doi. org/10.1007/s12633-011-9079-6. 33. Matinlinna JP, Lassila LVJ, Ozcan M, Yli-Urpo A, Vallittu PK. An introduction to silanes and their clinical applications in dentistry. Int J Prosthodont. 2004;17:155–64. 34. Matinlinna JP, Lassila LVJ, Vallittu PK.  Evaluation of five dental silanes on bonding a luting cement onto silica-­coated titanium. J Dent. 2006;34:721–6. https://doi.org/10.1016/j.jdent.2006.01.005. 35. Özcan M, Matinlinna JP, Vallittu PK, Huysmans M-C. Effect of drying time of 3-­methacryloxypropyltrimethoxysilane on the shear bond strength of a composite resin to silica-coated base/noble alloys. Dent Mater. 2004;20:586–90. https://doi.org/10.1016/j.dental.2003.10.003. 36. Fradeani M.  Reabilitação Estética em Prótese Fixa. Quintessence: São Paulo; 2006.

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Dentin Hypersensitivity and Cracked Teeth Eduardo Bresciani, Carlos Rocha Gomes Torres, and Annette Wiegand 18.1

Dentin Hypersensitivity – 692

18.1.1 18.1.2 18.1.3 18.1.4 18.1.5 18.1.6

 efinition – 692 D Epidemiology – 692 Etiology – 692 Dentin Hypersensitivity Mechanisms – 694 Diagnosis – 694 Management of Dentin Hypersensitivity – 694

18.2

Cracked Teeth – 696

18.2.1 18.2.2 18.2.3 18.2.4 18.2.5 18.2.6 18.2.7

 efinition – 697 D Epidemiology – 697 Etiology – 698 Diagnosis – 699 Mechanism of Pain – 699 Management of Cracked Teeth – 699 Prognosis – 702

References – 702

© Springer Nature Switzerland AG 2020 C. R. G. Torres (ed.), Modern Operative Dentistry, Textbooks in Contemporary Dentistry, https://doi.org/10.1007/978-3-030-31772-0_18

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Learning Objectives The learning objectives of this chapter are: 55 To define the term "dentin hypersensitivity" and gain knowledge on epidemiology, pain mechanisms, diagnosis, and treatment options for dentin ­hypersensitivity. 55 To inform about diagnosis, epidemiology and management of cracked teeth.

18.1

Dentin Hypersensitivity

18.1.1

Definition

Dentin hypersensitivity is defined as short and sharp painful sensitivity, triggered by tactile, thermal, chemical, osmotic, or evaporative stimuli applied to exposed dentin. It is not related to any other pathology, so conditions with similar symptoms, i.e., cracked tooth syndrome (to be discussed further in this chapter), chipped teeth, fractured restorations, postoperative sensitivity, or pulpitis, have to be excluded [77]. Dentin hypersensitivity is also referred as dentin hyperesthesia, dentin sensitivity, sensitive dentin, and root sensitivity, among others. The term “dentin hypersensitivity” may not be most adequate, as this scenario is not related to pulpal inflammation, but it will be the preferred term in this chapter as it is the most used term. Dentin hypersensitivity is defined as short and sharp painful sensitivity, triggered by tactile, thermal, chemical, osmotic, or evaporative stimuli applied to exposed dentin, not related to any other pathology.

18.1.2

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Epidemiology

Epidemiological data on the prevalence of dentin hypersensitivity vary distinctly depending on the study population, methods of examination (clinical examination, questionnaire), and diagnostic criteria. A recent review by West et al. [77] showed that the prevalence of dentin hypersensitivity ranged from about 2 to 98%, with periodontal patients presenting higher values (60 to 98%) than adult patients (up to 50%). Premolars are more often affected from dentin hypersensitivity than molars and canines; moreover, it is slightly more prevalent in the upper jaw than in the lower jaw [52, 84]. Age and gender distribution of dentin hypersensitivity show conflicting evidence. Mostly, a peak of dentin hypersensitivity can be observed in patients around 30 to 40 years. In older patients, dentin hypersensitivity is probably reduced due to tertiary dentin formation and a lower number of teeth,

which potentially might be at risk for developing dentin hypersensitivity [71, 77]. Conflicting data exist on higher prevalence of dentin hypersensitivity in female patients [52, 61, 78], which might exhibit a more healthy lifestyle (e.g., more extensively brushing, higher consumption of “healthy,“potentially erosive food) compared to men. Overall, prevalence of dentin hypersensitivity seems to increase, as the population ages and teeth are retained for a longer time period [47]. >> Dentin hypersensitivity is more prevalent on patients with periodontal problems, and the premolars are the more affected teeth. The peak occurs in patients around 30 to 40 years.

Patients seeking treatment for dentin hypersensitivity report a considerable impairment of their oral health-related quality of life, as eating, drinking, and oral hygiene habits were affected [8]. 18.1.3

Etiology

Dentin hypersensitivity may occur when dentin is exposed to the oral environment, as a result either of enamel loss or of root exposure with loss of cementum (. Fig. 18.1). Attachment loss is probably the most relevant factor leading to root exposure and dentin hypersensitivity. Especially, patients with gingival recessions (. Fig.  18.2) are affected from dentin hypersensitivity [66, 78]. Gingival recession is defined as displacement of the gingival margin apically to the cemento-­ enamel junction and is a common entity even in younger adults with a healthy periodontium [55, 66]. Prevalence data on the percentage of people affected from gingival recession range from 30% to 100% [39]. Besides inflammation, predisposing factors for the development of gingival recession comprise morphological conditions of the bone (e.g., dehiscence, fenestration) and soft tissue (e.g., thickness of keratinized gingiva, frenum position), orthodontic tooth movement,  

 

..      Fig. 18.1  Scanning electron microscopic image of a dentin surface with open tubules

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..      Fig. 18.2  Recessions at mandibular incisors due to exaggerated brushing

and/or oral hygiene (e.g., toothbrushing frequency and duration, scrub method, bristle hardness) [26, 29, 39]. If left untreated, gingival recession has a high probability for progression [14]. Dentin hypersensitivity can also occur as consequence of periodontitis or periodontal treatment. Scaling and root planing might lead to hypersensitivity in symptom-free teeth and increased hypersensitivity in already affected teeth. Potential differences with respect to dentin hypersensitivity between various instruments and devices for scaling and root planing were not investigated so far. Not only conservative but also surgical intervention increases dentin hypersensitivity [18]. The main reason for enamel loss is tooth wear by erosion, abrasion, abfraction, and/or attrition. Erosive tooth wear is defined as dental hard tissue loss due to a chemical-­ mechanical process not involving bacteria [13]. Erosive tooth wear is initiated by extrinsic or intrinsic acids undersaturated with respect to tooth mineral, which demineralize the surface and make it more prone to physical wear. Extrinsic acids come mainly from diet, and frequency and duration of consumption determine the severity of erosive demineralization. Extrinsic acids from professional work and practice of sports are also important; however, they might be considered as secondary factors regarding erosive tooth wear [7]. Exposure to gastric acid by reflux disease, eating disorders, or alcoholism might cause intrinsic erosion (. Fig. 18.3) [40]. Compared to dietary acids, the pH of gastric acid is much lower, leading to more severe erosive lesions. Saliva plays an important role in the prevention of erosion by deluting, removing, and buffering acidic substances. Moreover, it forms a protective salivary pellicle on the tooth surface. By providing mineral ions, saliva might also modify the de- and remineralization process. Thus, patients presenting hyposalivation are more prone to erosion [24, 25]. Mechanical forces might increase erosive wear but might also act as the sole factor causing tooth wear. Abrasion results from friction between teeth and other materials and attrition  

..      Fig. 18.3  Patient with severe erosive tooth wear due to bulimia

..      Fig. 18.4  Abrasive tooth wear and recession due to toothbrushing with self-made very abrasive toothpaste

from antagonist tooth-tooth contact, and abfraction is discussed to be a result from abnormal occlusal loading leading to tensile stress in the cervical area [68]. Abrasion can be caused by abnormal oral hygiene depending on toothpaste, toothbrush, and the toothbrushing frequency and force (. Fig. 18.4) [79]. To a certain extent, erosive and mechanical tooth wear can be considered as physiological, but especially the interaction between erosion, abrasion and attrition might lead to increased wear exposing dentin. As erosive and mechanical processes often interact, a precise differentiation of tooth wear lesions is often challenging. Erosive tooth wear affects initially the palatal and occlusal surfaces (intrinsic erosion) or the labial surfaces (extrinsic erosion). Erosive tooth wear starts with a silkyshining surface progressing into concavities (smooth surfaces) or grooves (cusps). On smooth surfaces, erosive tooth wear is characteristically located coronal from the CEJ and presents an intact border of enamel along the gingival margin. On occlusal and incisal surfaces, progression of erosive tooth wear finally results in a complete destruction of the morphology.  

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Tip

Erosive tooth wear starts with a silky-shining surface progressing into concavities (smooth surfaces) or grooves (cusps). On smooth surfaces, erosive tooth wear is characteristically located coronal from the enamel-cementum junction and presents an intact border of enamel along the gingival margin.

decreases from the pulpal dentin to the DEJ. Hypersensitive dentin presents more and wider dentinal tubules than nonsensitive dentin. However, exposed dentin is not necessarily associated with hypersensitivity, as permeability is reduced in sclerotic dentin. Also, the presence of a smear layer, i.e., resulting from removal of the cementum layer during root debridement, might reduce permeability temporarily [49]. 18.1.5

Attrition appears as flat facet with a shiny appearance and distinct margins. Corresponding facets can be found at antagonistic teeth. Abrasive defects can hardly be distinguished from primarily erosive lesions as these phenomena clinically often overlap [20]. Non-carious cervical lesions (wedge-shaped lesions) are probably the result of an interaction of erosion, abrasion, and attrition. The evidence for abfraction to be causative in the development of wedge-­ shaped defects is meanwhile critically discussed [68]. In contrast to erosive lesions, wedge-shaped lesions are located apical from the CEJ and have sharp margins [20, 68]. Lesion depth and morphology contribute to dentin hypersensitivity [44]. 18.1.4

18

Dentin Hypersensitivity Mechanisms

Several mechanisms of action were described in the literature to explain dentin hypersensitivity [9, 10]. The most accepted mechanism defining dentin hypersensitivity is based on the hydrodynamic theory described by Brännström [9]. This theory proposes that dentin hypersensitivity is the result of rapid fluid movement in the dentin tubules due to external stimuli, typically thermal, tactile, evaporative, osmotic, and chemical triggers. Stimulus-induced fluid flow might activate nerve endings, (A-β and A-δ fibers) at the dentin-pulp interface; the excited nerve terminations are considered as mechanoreceptors. The sudden movement of dentin fluids might be directed outward or inward, depending on the kind of stimuli. Cooling, drying, evaporation, and hypertonic solutions produce an outward flow, which generates more pain than inward flow due to heat application [17].

Diagnosis

Information about the presence and severity of dentin hypersensitivity can be obtained from a proper anamnesis and clinical examination, which should be routinely done. Verbal screening includes questions about pain during drinking or eating hot, cold, or acidic drinks or food or during toothbrushing. Furthermore, pain characteristics (site, severity, duration, character) should be recorded. Then, information about personal behavior patterns (consumption of acidic food or drinks, intrinsic erosion, toothbrushing) and about previous dental treatment (restorative treatment, dental bleaching, periodontal treatment) should be obtained before a clinical examination is undertaken. During clinical examination, conditions with similar symptoms, i.e., caries, fracture restorations, teeth, postoperative sensitivity, microleakage, or pulpitis, must be excluded. If dentin exposure due to enamel loss or root exposure can be detected, tactile (dental explorer) and thermal/evaporative stimulation (air stream) should be performed. Ideally, two different stimuli should be applied to confirm the diagnosis. Pain intensity and quality should be documented (e.g., by numerical rating scales) [21, 74]. One frequently used score is the Schiff cold air sensitivity scale [62]: 0. Subject does not respond to air stimulus. 1. Subject responds to air stimulus but does not request discontinuation of stimulus. 2. Subject responds to air stimulus and requests discontinuation or moves from stimulus. 3. Subject responds to air stimulus, considers stimulus to be painful, and requests discontinuation of the stimulus. Additionally, the impairment of the oral health-related quality of life can be assessed by using suitable instruments like the Oral Health Impact Profile [21, 74].

>> Dentin hypersensitivity is the result of rapid fluid movement in the dentin tubules which might activate nerve endings.

18.1.6

The other theories proposed to explain dentin hypersensitivity comprise the neural theory and the ondontoblastic transduction theory. The neural theory suggests that dentin is innervated and nerve endings within the dentinal tubules are directly activated by the stimulus. The odontoblastic transduction theory assumes that the stimulus is transmitted along the odontoblast via synaptic junctions to the sensory nerve endings [76]. Usually, the superficial dentin is less permeable than deeper layers as the number and diameter of tubules per area

The management of dentin hypersensitivity usually follows a stepwise approach based on the extent and severity of the condition. Based on a correct diagnosis, potential risk factors for tooth wear and gingival recession (diet, intrinsic erosion, oral hygiene, etc.) must be identified and eliminated or at least modified (dietary advice, oral hygiene advice). Non- and minimally invasive strategies include the application of products, which aim to suppress the pulpal nerve response or to mechanically occlude dentinal tubules; prod-

Management of Dentin Hypersensitivity

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ucts can be self-applied at home (e.g., toothpastes) or professionally applied (e.g., sealants) in the dental office. If dentin hypersensitivity persists and goes along with a cervical defect or gingival recession, restorative treatment or mucogingival surgery can be considered [38, 63]. 18.1.6.1 Elimination or Reduction of Etiological

Factors

Different etiological factors might contribute to the development of dentin hypersensitivity. With regard to erosive tooth wear, recording of dietary intake might be helpful to identify acidic sources, i.e., fruit juices, soft drinks, sport drinks, or sour sweets [59]. Frequency of consumption, i.e., by avoiding dietary acids between meals, and contact time with dietary acids should be significantly reduced [45, 46]. In case of intrinsic erosion, referral to an appropriate medical specialist becomes necessary. Stimulation of salivary flow or the use of saliva substitutes might be indicated if erosive tooth wear is associated with hyposalivation. Tip

For extrinsic erosion, recording of dietary intake might be helpful to identify acidic sources and frequency of consumption. Thus, the contact time with dietary acids can be significantly reduced. In case of intrinsic erosion, referral to an appropriate medical specialist becomes necessary. Stimulation of salivary flow or the use of saliva substitutes might be indicated if erosive tooth wear is associated with hyposalivation.

Incorrect toothbrushing might contribute to the development of gingival recession and tooth wear [26, 79]. Oral hygiene advice therefore comprises correct toothbrushing techniques (depending on the kind of toothbrush used) and reduced toothbrushing force. High-abrasive toothpastes should be avoided. 18.1.6.2 Non- and Minimally Invasive

Treatment

The noninvasive treatment of dentin hypersensitivity comprises the occlusion of dentinal tubules or nerve desensitization. For occlusion of dentinal tubules by mineral precipitation, various products containing strontium, arginine, stannous fluoride, or calcium compounds have been developed. Nerve desensitization is induced by agents containing potassium salts. An increase in extracellular potassium is thought to result in a sustained depolarization and axonal accommodation, making the nerve less excitable to further stimulation [23, 37]. At-home treatment of dentin hypersensitivity is mainly done by desensitizing toothpastes. Toothpastes containing potassium, stannous fluoride, calcium sodium phosphosilicate, arginine, and nano-hydroxyapatite presented a significant desensitizing effect compared to placebo treatment due to mineral precipitation in the dentinal tubules, while stron-

tium or amorphous calcium phosphate-containing toothpastes were less effective [3, 28]. A large number of prophylaxis pastes and varnishes are available for professional application. Prophylaxis pastes containing arginine and calcium carbonate or calcium sodium phosphosilicate were shown to have some effect on dentin hypersensitivity [19, 34, 41]. Varnishes form a waterproof film on the surface leading to some physical occlusion of the dentinal tubules. Additionally, different active agents, like fluoride, oxalate, or glutaraldehyde, are incorporated. Fluoride varnishes form calcium-fluoride precipitates and fluorapatite which occlude dentin tubules and reduced dentin hypersensitivity for several weeks [50]. Glutaraldehyde coagulates protein in the dentinal tubules; oxalate forms ­calcium oxalate crystals that occlude the dentinal tubules. Systematic reviews found that these in-office treatments were effective in reducing dentin hypersensitivity when compared to placebo treatments [34, 41]. Alternatively, the use of lasers has been suggested. High-power lasers, such as Nd:YAG, Er:YAG, or CO2, may obliterate the dentinal tubules by a melting or  thermomechanical ablation mechanisms and/or the evaporation of superficial dentinal fluid, reducing flow within the dentinal tubules. Low-power lasers, such as GaAlAs and He-Ne, may reduce pulpal nerve impulse conduction and exhibit photobiomodulating effects on cellular activity, enhancing the formation of tertiary dentin [36, 67]. However, different laser treatments were shown to decrease dentin hypersensitivity compared to placebo treatment, but mostly did not result in a superior performance compared to agents inducing chemical or physical occlusion of dentinal tubules [34, 36, 67]. Finally, dental adhesives (. Fig. 18.5) or sealants can be used for physical occlusion of dentinal tubules [34]. In conclusion, various treatment agents and regimens were shown to be effective in reducing dentin hypersensitivity compared to placebo. Due to the high variety of products and techniques and the heterogenous study designs, superiority of one agent/regimen can hardly be demonstrated. Moreover, placebo effects are commonly observed in the treatment of dentin hypersensitivity.  

18.1.6.3 Invasive Treatment

If dentin hypersensitivity is associated with a significant loss of dental hard tissue, restoration of the defect is a valid option, especially if non- and minimally invasive treatment failed. The restoration of non-carious cervical lesions can be done with resin-modified glass ionomers or composites, the latter placed via two-step self-etch or three-step etch and rinse adhesives (. Figs. 14.39, 14.40, 14.41, 14.42, 14.43, and 14.44) [60, 64]. Risk of retention loss is slightly lower for resin-modified glass ionomers (annual failure rate: 1.8%) than for composite restorations (3.4–4.1%) [64]. In case of gingival recession, surgical therapy for root coverage can be performed, leading to significant reduction of dentin hypersensitivity [16]. A variety of surgical procedures have been introduced [73], but the decrease of dentin hypersensitivity could not be related to a specific surgical  

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b

c

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18 ..      Fig. 18.5  Application of a desensitizing dental adhesive for mechanical blocking of dentin tubules. a Drying of dentin surface with air stream, b product application, c slight drying, d light-curing, e cervical area covered by the material

procedure [16]. If gingival recessions are associated with non-carious cervical lesions, a combined restorative surgical approach can be considered [2]. 18.2

Cracked Teeth

Cracked tooth syndrome describes a group of clinical signs and symptoms associated to the presence of incomplete fractures involving enamel and dentin, often extending to the pulpal chamber and/or periodontal area [12, 42].

Cracked tooth syndrome is a group of clinical signs and symptoms associated with the presence of incomplete fractures involving enamel and dentin, often extending to the pulpal chamber and/or periodontal area.

This is a situation of hard clinical diagnosis related to lack of knowledge by the dentists and to pain perception by patients, often distorted. The clinical scenario is usually reported by

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patients mainly as acute pain of short duration present during mastication, or after thermal stimulus, generally related to cold food or drinks [11, 12, 15, 72]. Other related symptoms may be pain after biting hard food (rebound pain) [11, 72] and/or after taking sugar or grainy food [5]. Radiographic examination is inconclusive [5]. Tip

The clinical scenario of cracked tooth syndrome is usually reported by patients mainly as acute pain of short duration present during mastication, or after thermal stimulus, generally related to cold food or drinks. Other related symptoms are pain after biting hard food and/or after taking sugar or grainy food.

The importance of this chapter is to help the readers to perform an early diagnosis and correct treatment plan, treating the tooth and maintaining its vitality and function, avoiding the fracture progression which would lead to complete fracture and possible tooth loss.

18.2.1

Definition

The American Association of Endodontists defines the term cracked tooth as an incomplete fracture initiated from the crown and extending subgingivally, usually directed mesiodistally [56]. Cracked teeth belong to longitudinal tooth fractures, which can be subdivided in craze lines, fractured cusps, cracked teeth, split teeth, and vertical root fractures [57]. Craze lines extend over marginal ridges and buccal and lingual surfaces in posterior teeth and appear as long vertical lines in anterior teeth but are confined to enamel (. Fig. 18.6). Fractured cusps, cracked teeth, and split teeth begin occlusally and extend apically, while vertical root fractures begin in the root. Fractured cusps are defined as complete or incomplete fracture involving at least two aspects of the cusp and extending to the cervical third of the crown or the root (. Fig. 18.7). In contrast to fractured cusps, cracked teeth are centered and the depth on the root varies (. Fig.  18.8). Cracked teeth are also described as greenstick fractures or tooth infractions. Progression of a cracked tooth results in a split tooth, which is defined as complete fracture initiated from the crown and extending the middle or apical part of the root (. Fig.  18.9). Vertical root fractures are initiated from the root and may involve one or both buccal and lingual proximal surfaces [56, 57].  

 

 

 

18.2.2

..      Fig. 18.6  Craze lines in enamel on teeth 11 and 12

a

Epidemiology

In patients suspected of having tooth cracks or presenting cracked tooth-like symptoms, about 10% of patients/teeth were in fact diagnosed with cracked teeth [31, 33, 75]. Cracked teeth are more prevalent at middle-aged and older patients [31, 53, 58, 75, 82], and molars are more often affected than premolars [31, 58, 75, 82], probably due to the proximity to the temporomandibular joint. Thus, eating course food, chewing on hard objects, and unilateral mastication were identified as risk factors for cracked teeth

b

..      Fig. 18.7  Cusp fracture. a Fractured lingual cusp of symptomatic tooth 15, disclosed by caries lesion indicator solution (5% basic fuchsin), b cusp fracture on gingival level was confirmed during the restorative procedure

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..      Fig. 18.8  Cracked teeth. a Incomplete fracture with mesiodistal direction observed on the pulpal and gingival walls of tooth 46 after removal of an extensive restoration; b mesiodistal incomplete fracture on upper molar observed after removal of an occlusal amalgam

restoration; c tooth 17 presenting partial loss of amalgam restoration and the presence of a crack line with buccal-lingual direction. d Tooth 16 after removal of extensive restoration. The fracture lines can be observed on the lingual groove and on the linguogingival line angle (arrows)

the antagonist (wedging effect) [22, 31]. It is also discussed that higher masticatory forces in men might be responsible for a higher prevalence of cracked teeth [31], although most studies reported a similar prevalence in men and women [58, 82]. >> Cracked teeth are more prevalent at middle-aged and older patients and molars are more often affected than premolars. Eating course food, chewing on hard objects, and unilateral mastication were identified as risk factors for cracked teeth.

18

Cracks occur in intact and restored teeth. If cracks occur in restored teeth, those with nonbonded restorations, such as gold and amalgam (. Fig. 18.8), are more often affected than teeth with bonded restorations (composite) or crowns [31, 58, 75, 82].  

..      Fig. 18.9  Split tooth. Mesiodistal fracture extending to the apical part of the root

[51]. Some studies found mandibular molars to be most frequently involved [31, 82]. It is discussed that maxillary molars are more resistant to cracks due the stabilizing occlusal oblique ridge [22]. Moreover, loading during mastication might be higher in mandibular molars, when the mesiopalatal cusp of the maxillary molar leads to fatigue in

18.2.3

Etiology

Intact, non-restored teeth often exhibit tooth cracks at the surface, developing in enamel or at the DEJ, which might progress into dentin, but are less likely to cause tooth fracture. Tooth fracture is more likely to occur from dentin cracks, which

699 Dentin Hypersensitivity and Cracked Teeth

might be a result of restorative procedures (e.g., removal of tooth structure) or fatigue caused by the restoration geometry [81]. The fatigue and fracture resistance of teeth is also depending on age, hydration, and temperature variations [81]. Natural predisposing factors responsible for the development and progression of cracks in intact teeth include morphological and physical factors, such as sudden biting on hard substances, eccentric contacts and interferences, wear, bruxism, malocclusion and anatomic form of the cusps, and the occlusal morphology (so-called wedging effect; see above) [35]. The fracture resistance of teeth is also reduced in the presence of carious lesions, requiring extensive preparation and resulting in large and/or deep cavities. Occlusal load stress during mastication and repeated thermal expansion of restorative material might cause an increased cuspal flexure inducing stress at sharp internal line angles of the cavity (gold, amalgam) and producing microcracks. Inadequate design features also comprise insufficient cuspal protection in inlay/onlay design or a deep cusp-fossa relationship [35]. Finally, stress concentration due to pin placement, physical forces during luting of indirect restoration, non-incremental placement of composite restorations, etc. might predispose crack formation [35]. 18.2.4

Diagnosis

The main clinical signs and symptoms of cracked teeth are pain on biting/chewing and sometimes on the release of pressure (rebound pain) and/or sensitivity to cold thermal stimuli [5, 27, 65]. Symptoms might be present for periods ranging from weeks to month, and patients might have difficulties in identifying the affected tooth. In the absence of pulpal inflammation, vitality testing usually gives a positive response, but an exaggerated response to cold thermal stimuli is possible. The pulpal and periapical diagnosis depends on the extent and orientation of the crack. Cracks might become colonized by bacteria arranged in biofilms, which might reach the pulp and periodontal ligament if the crack progresses [54]. Cracks with pulpal involvement might result in pulpitis or pulp necrosis, which makes the diagnosis of cracked teeth sometimes challenging. Periodontal probing is necessary to disclose the depth of the crack. Cracked teeth with periodontal probing depths exceeding 4 mm are more likely to show pulp necrosis than cracked teeth with a periodontal probing depth of 3  mm or less [82]. Radiographic examination rarely improves the detection of cracks, as fractures in mesiodistal direction are usually not visible, but is essential to determine the periodontal and periapical status. Tip

The main clinical signs and symptoms of cracked teeth are pain on biting/chewing and sometimes on the release of pressure (rebound pain) and/or sensitivity to cold thermal stimuli.

18

Symptoms can be provoked by loading of individual cusps (so-called bite test) by specific instruments (Tooth Slooth  – Professional Result and FracFinder  – Denbur) (. Fig. 18.10). Each cusp should be tested separately. Biting tests can be also performed with wood sticks or cotton rolls (. Fig. 18.11), but instruments were shown to be more reliable [83]. Visual detection of cracks is improved by using magnifying loupes/microscopes, dyes (. Figs. 18.7 and 18.12), fiber-­ optic transillumination (. Fig.  18.13), or light-induced fluorescence (. Fig.  18.14). In case of restored teeth, especially in case of amalgam fillings or gold restorations, removal of restorations is necessary to detect fracture lines (. Fig. 18.8). Then, wedging forces can be applied to determine if tooth segments are separable (split tooth, see above) or not (cracked tooth). As differential diagnosis dentin hypersensivity, postoperative sensitivity, fractured restorations, occlusal trauma or parafunctions must be considered.  

 

 

 

 

 

18.2.5

Mechanism of Pain

The pain associated with loading or loading release is explained by the movement of dentinal fluid due to movement of fractures sites (hydrodynamic theory). In this case, the painful response is fast and intense due to activation of Type A myelinated nerve fibers [43]. Pain related to pulp inflammation is characterized by a short, sharp pain, indicative of A-delta fiber activation, followed by a prolonged, dull ache, indicative of C-fiber activation [30]. 18.2.6

Management of Cracked Teeth

Early diagnosis is very important to reduce progression and, thus, involvement of pulp and periodontium. Ideally, predisposing factors (see etiology 18.2.3) should be controlled to avoid the formation of cracks. Treatment of longitudinal fractures depends on the extent and depth. Root canal treatment might be necessary in case of pulpal inflammation/ necrosis. If the crack extends to the root surface and leads to extensive attachment loss, extraction or  – in case of multi-­ root teeth  – hemisection/root amputation must be considered. Restorative treatment of incomplete coronal fractures not involving pulp or periodontium aims to immobilize and bind the fractured segments. If possible, the margins of the restoration should cover the crack to its full extent. Historically, orthodontic bands, copper rings, or temporary crowns were suggested for immediate treatment, but such restorations are time-consuming, invasive, and/or costly [6]. Alternatively, the placement of direct composite splints for short-term management of cracked teeth is suggested, but comes along with transient side effects, e.g., problems with chewing [4]. In many cases, initial treatment can be performed by placing intracoronal composite restorations to control if treatment leads to an improvement or complete relief of symptoms. Composite restorations can be also con-

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..      Fig. 18.10  Instrument for detecting cracked teeth. a The instrument (FracFinder) presents a flat and non-skid surface to rest on the opposing tooth of that being tested. The opposite surface presents a concavity

a

that can be adapted to the suspected cusp, concentrating the load on the individual cusp. b Test being performed on buccal cusp of tooth 24. c Test being performed on the same tooth but on lingual cusp

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..      Fig. 18.11  Load test and devices used to stimulate painful symptoms during the detection of cracked teeth. a Test performed with wooden tongue depressor; b test being performed with cotton

roll. Both tests might detect teeth with fracture, but specific detection of the involved cusp is not clear

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..      Fig. 18.12  Tooth 46 presenting incomplete fracture and rebound pain reported by the patient during mastication. a Clinical aspect of the occlusal surface showing a class I amalgam restoration; b lingual view of the tooth, showing a clinically detected fracture line at the

a

lingual groove extended gingivally (arrow); c fracture line observed after removal of the restoration at the linguogingival line angle on the distolingual cusp (arrow). The fracture was evinced by a plaque disclosing solution

b

..      Fig. 18.13  Fiber-optic transillumination for detection of cracks. a Aspect of the cracked teeth under natural light; b fractures clearly visible under transillumination

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..      Fig. 18.14  Observation of tooth cracks by light-induced fluorescence using intraoral QLF camera (Qraypen, Inspektor Research Systems). a Tooth illuminated by white light. b Tooth illuminated by blue light, showing red fluorescence in the cracks due to the bacterial penetration

18

sidered for permanent treatment. Opdam et  al. [48] evaluated the effectiveness of composite restorations without cuspal coverage for managing cracked teeth and found a mean annual failure rate of 6% (need for endodontic treatment) after 7 years. No failures were observed when composite restorations were performed with cuspal coverage. Seventy-five percent of teeth were free of any symptoms during the observation period [48]. Another study evaluated cracked teeth restored with indirect composite onlays and found 93% of teeth free of symptoms after an observation period of 6 years [69]. Krell and Rivera monitored the outcome of symptomatic cracked teeth with reversible pulpitis after treatment with a full coverage crown [33]. All teeth were retained over a period of 6 years, but 20% needed root canal treatment. A recent study by Wu et  al. [80] showed that cracked teeth permanently restored with a crown had a better pulpal prognosis than cracked teeth that remained cemented with orthodontic bands. However, clinical trials comparing different restorative approaches for successful treatment of cracked teeth are missing so far, so superiority of full crown coverages against onlay/cusp coverages and/or intracoronal composite restorations is not proven yet. 18.2.7

Prognosis

In vital and asymptomatic or newly symptomatic teeth, pulpal inflammation is considered reversible, and restorative treatment of the cracked tooth is in focus. However, late diagnosis or crack propagation might lead to irreversible pulpitis or pulp necrosis making root canal treatment necessary. Studies by Abbott and Leow [1] and Krell and Rivera [33] showed that about 20% of cracked teeth with reversible pulpitis required root canal treatment within the first 3 to 6 months after diagnosis, while 80% of the cases remained stable over 5 to 6 years. Similarly, Wu et al. [80] found about 70% of cracked teeth with reversible pulpitis to remain

healthy over 3 years. The prognosis is less favorable in teeth with deep probing depth, which indicates that the crack progressed into the root surface [32]. The survival rate of cracked teeth after root canal treatment amounts to 90% over 2 years [31] or 92% over 5 years [70]. Teeth with a probing depth of more than 6 mm again had a worse prognosis compared to teeth with a probing depth of less than 6 mm [31]. Moreover, cracks with extension onto the pulpal floor increased the risk of the tooth being extracted [70]. Conclusion This chapter covered clinical conditions related to dental sensitivity not associated  to the caries diseases, which are the dentin hypersensitivity and the cracked tooth syndrome. The most relevant information about dentin hypersensitivity was presented, including its etiology, mechanisms, and diagnosis. The treatment by elimination or reduction of etiological factors and other options were described. The importance of performing an early diagnosis and correct treatment plan of cracked tooth syndrome was described. The specific tools and methods for diagnosis were explained, as well the treatment options and prognosis. Many clinicians do not have enough knowledge about this specific problem, and the lack of a prompt and precise diagnosis can allow the progression of the crack to a complete fracture that can cause tooth loss.

References 1. Abbott P, Leow N. Predictable management of cracked teeth with reversible pulpitis. Aust Dent J. 2009;54:306–15. https://doi. org/10.1111/j.1834-7819.2009.01155.x. 2. Agossa K, Godel G, Dubar M, SY K, Behin P, Delcourt-Debruyne E. Does evidence support a combined restorative surgical approach for the treatment of gingival recessions associated with noncarious cervical lesions? J Evid Based Dent Pract. 2017;17:226–38. https:// doi.org/10.1016/j.jebdp.2017.04.001.

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705

Supplementery Information Index – 707

© Springer Nature Switzerland AG 2020 C. R. G. Torres (ed.), Modern Operative Dentistry, Textbooks in Contemporary Dentistry, https://doi.org/10.1007/978-3-030-31772-0

707

A–C

Index

A Abfraction  8, 9, 11, 483, 507, 693, 694 Abnormal formation of the enamel  483 Abrasion  6, 8–11, 27, 31, 125, 132, 141, 142, 151, 158, 159, 488, 693, 694 Abrasive  125, 131, 132, 139, 141–143, 145, 148, 157, 158 –– discs 402 –– pastes  402, 405 –– rubber  402, 405 –– rubber point  593, 626 –– strip(s)  405, 627 Abrasive-impregnated rubber  143 Absorbing pads  253, 256, 257 Absorption range  437, 442, 443, 448 Accident  52, 59, 63, 64 Acetate band  270 Acid etching  303, 307, 309, 312, 320, 578, 605, 628 Acidic monomer  578 Acidogenic  79–81, 87, 119 Aciduric  80, 81 Actinic damage  460 Activator 437 Active medium  160, 161, 163, 447 Addition-fragmentation monomer  618 Addition silicone  682 Adhesive pooling  599, 600 Adhesive restoration  185, 188, 197, 203, 205, 210, 218 Adhesive system  303–308, 313 Aesthetics  184, 194, 668, 669, 672, 675, 681, 686, 689 –– smile 668 Aging physiological process  294, 295 Air abrasion  685 Airborne particle abrasion  158, 583, 584 Aliphatic amine  437 Allergy(ies)  2, 4, 5, 29, 407 Alloy –– admixed 376 –– dispersed phase  376 –– fine cut  376 –– lathe cut  375 –– regular cut  376 –– spherical  376, 390 Aluminum oxide  131, 143, 158 Amalgam  184, 185, 187, 202, 204, 205, 208, 219, 336, 374–379, 384–386, 388–393, 397, 402, 405, 407, 408, 412, 413, 415, 416, 419–422, 424–426, 429, 431 –– well 385 Amalgamator  385, 388 Amalgapin  416, 417, 419, 420, 422, 425, 431 Amelogenesis imperfecta  8, 15, 16 American Dental Association (ADA)  146 American National Standards Institute (ANSI) 146 American Society of Anesthesiology (ASA)  29 Ammonia forming agents  641 Anamnesis  2, 3, 6, 7, 32, 40, 96, 296, 300, 315, 320 Anatomic wedges  276

Anesthesia  200, 583, 621 Angle –– axiopulpal 208 –– of beam spread  454, 455 –– cavosurface  172, 204 –– external line  170, 208, 350, 360, 363 –– incisal line  172 –– incisal point  172 –– internal line  208 –– line  170, 172 –– margin 204 –– point 170–172 Anionic detergents  306, 313, 317 Antisepsis  492, 497 Area of visibility –– dynamic  672, 675 –– static 672 Arginine  641, 695 Argon-ion laser  442, 447 Arkansas stone  142, 143 Arms  45, 46, 50, 56, 65, 67, 70 Aromatic tertiary amine  437 Articulating paper  200, 336, 339, 492, 569, 583, 592, 626 –– forceps  336, 583 Artificial dentin  378 Artificial retention  415, 420, 431 Assistant  52–54, 56, 57, 59, 68 Astringent solution  255 Atomizing 376 Attenuation of light  457 Attrition  6, 8, 9, 11, 31, 693, 694 Auxiliary  52, 58

B Bactericidal effect  306 Band –– cellulose 268 –– clear  269, 586 –– matrix  378, 379, 384, 391, 392 –– Mylar 268 –– plastic  270, 276, 277 –– polyester 268 –– polyvinyl chloride  268 –– pre-contoured polyester  269 –– straight  263, 264, 278, 285 –– Tofflemire 263 Band-pass filter  442–444, 448, 452 Barton 394 Base  307–309, 311, 581, 585, 618, 619 Beer–lambert law  457 Bennett  156, 378, 391, 397 Benzoyl peroxide  437 Bevel  493–497, 499, 506, 507, 513, 534, 551, 554, 584, 622, 623 Bioactive  581, 582 –– glass 641 –– molecules 312 Biocompatible 581 Biofilm  78–84, 86, 88, 89, 91, 93, 97, 100, 105, 110, 119, 194, 202, 204, 215, 218, 220, 467, 483, 492, 496, 507, 569 –– control of  632

Biological principles  185 Biological sealing  90, 92, 97 Biologic width  194, 197, 499, 538, 539, 544, 546 Biomaterial 681 Biomimetic 581 Biopulpectomy 301 Bis-acryl composite  669, 682 Bite test  699 Biting blocks  251, 255 Biting force  184, 195 Black, G.V.  168, 172, 174, 177, 200 Blade  125, 127, 128, 130–132, 139–141, 148, 152, 155 Blot drying technique  306, 313, 497, 498, 686 Blue light  442, 443, 446–448, 460, 461 Bonded amalgam  426 Bonding  578, 580, 583, 585, 586, 596, 623, 626, 628 Bonding interface rupture  585 Bone morphogenetic proteins (BMP)  310, 311 Boomerang 263 Bow compass  556, 559 Broad-spectrum  442, 448 Brushes  143, 145, 154 Brushing technique –– Bass 635 –– Charters 634 –– Fones 634 –– Stillman 634 Brush, interdental  635, 636 Bruxism  11, 12, 23, 31, 210, 483, 555, 556, 581, 669 Buccal corridor  23, 25, 27 Bulk-fill  617, 618 Bulk increment  585 Bur(s) –– cone  143, 146 –– cylinder  146, 348 –– inverted cone  135, 146, 155 –– multi-bladed 140 –– neck  127, 138, 139, 147 –– round 146 –– spherical 146 –– straight fissure  146 –– taper 146 –– tapered fissure  146 Burnisher  152, 155 –– egg  378, 391, 397, 600 –– round 397 Butt joint  672, 673, 676

C Calcium carbonate  143 Calcium compounds  695 Calcium fluoride  82, 695 Calcium hydroxide  219 –– cement  307, 310 –– paste  310, 320 –– powder  309, 310 –– solutions  306, 313, 314, 323 –– suspensions 310 Calcium sodium phosphosilicate  695 Camphorquinone  442, 443, 447, 448, 451

Index 708

Canines  489, 491, 518 Capping  618, 619 Capsules  499, 506, 513, 519 –– pre-proportioned  377, 385, 388, 408, 409 Carbide  143, 145 Carbon steel  139, 143 Carborundum 143 Cardiac disorders  4 Caries –– active lesion  97 –– activity  632, 640 –– acute lesion  89, 97, 312 –– arrested lesions  93 –– chronic lesion  87 –– confounding factors  79, 80 –– detector dyes  216 –– disease  86, 90, 94, 95, 643, 654, 660 –– ecological plaque hypothesis  81 –– hidden lesion  89, 90 –– inactive lesion  88, 97 –– infiltration 653 –– non-specific plaque hypothesis  80 –– primary determinant factor  79 –– rampant lesion  81 –– risk  28, 633, 639, 640, 643, 644, 650, 653, 660 –– root  92, 114 –– secondary determinant factor  79 –– secondary lesions  110–114 –– specific plaque hypothesis  80 –– wall lesions  110 Caries lesion –– active 184 –– inactive 184 –– recurrent  578, 584 Cariogenicity 633 Carious lesion  291, 295, 296, 302, 312, 315 Carious tissue, removal of  200, 209 Carpule syringe  157 Carriers  155, 156 Carver –– cleoid  155, 379, 392 –– contour carbide  626 –– discoid  155, 379, 392 –– Frahm  155, 378, 379, 391 –– Hollenback  155, 378, 391–393, 400, 431 Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)  641 Cataract 460 Cavitation 185 Cavity(ies) –– complex 173 –– compound 173 –– configuration factor  439, 453 –– floor 172 –– preparation testing  301 –– simple 173 –– varnish 308 –– wall  187, 204 Cavosurface angle  494–497, 500, 506, 507, 520, 523, 534, 569, 573 Cement  185, 209, 668, 678, 682–684, 686 Cementoenamel junction (CEJ)  192, 488 Centric contact  583, 626 Centric occlusion (CO)  23, 200, 492, 559, 583, 626 Centric relation  23 Ceramic  668, 669, 681–685, 689 –– ingot 683 –– laminate 683

Cervical lesions  496, 497, 508, 511, 513 Cervicoincisal depth cut  675 C-factor  439–441, 584, 586 Chair  53, 54, 57, 58, 67, 68, 74 Chameleon effect  468 Chamfer finish line  675 Characterization 592 Characterization material  559, 678, 679 Cheek retractor  251, 254 Chemically activated  437, 441, 450 Chemical stimulus  694 Chewing gum  633, 640–642 Chief complaint  32, 33, 40, 296 Chip 628 Chipped teeth  692 Chisel  125, 128, 129, 131 Chlorhexidine  219, 306, 492, 497, 640 Chroma  507, 562 Chromatic alterations  669, 681 Chu’s Aesthetic Gauge  490, 556 Circumferential matrix  600, 604 Clamp(s) –– gingival retraction  227, 235 –– winged  227, 240 –– wingless  227, 229, 244 Classification –– artificial  174, 177 –– Black’s  174, 177 –– Class I  338, 359, 361, 363, 370, 580, 585, 604 –– Class II  350, 361, 362, 582 –– Class III  482, 496, 584 –– Class IV  496 –– Class V  365, 366, 469, 482, 496, 499, 507, 513, 518 –– Class VI  581 –– etiologic 174 –– Mount and Hume’s  177, 179 Cleaning  219, 220 Cleaning agents  305, 306 Cleaning of the preparation  344, 362, 364, 370 Clenching 581 Clinical assessment  17 Clinical chart  23, 32, 33 Clinical examination  23, 33, 40, 296, 323 Coefficient of linear thermal expansion (CLTE)  466, 580, 612 Coherent 447 Cold pulp testing  296 Collagen fiber  188, 578 Collimated  447, 448 Color changes  14, 15, 21 Color-masking 658 Color modifier(s)  472, 473, 559, 679 Color perception  470, 471 Commissural line  23 Composite  220, 466, 506, 550, 578–629, 668, 669, 679, 687 Compound Class I  394, 397 Compound preparation  338, 344 Compression load  198 Compressive strength  204, 412 Compressive stress  198 Compules 506 Compulsory notification of infectious diseases 4 Computer-aided design/computer-assisted machining (CAD/CAM)  185, 681–683 Concentricity 147

Condensable 613 –– composites 469 Condensation  375, 376, 378, 384, 385, 388–391, 406, 409 Condensers 154 Cones  139, 143 Conical teeth  12 Connective tissue attachments  194 Connective tissues  20, 28 Conservative composite restoration  632, 650–652 Conservative preparation  650, 652 Contact(s) –– centric 583 –– forming instrument  621, 629 –– eccentric 583 –– tightness  600, 604, 613, 626 –– tooth-to-tooth 583 Continuous curing cycle  453 Contra-angle  127, 134, 137, 139, 142, 149 Control phase  29, 30 Convenience form  213, 340, 344, 348, 361, 363, 369, 493, 583, 584 Conventional curing protocol  436, 453 Copper  374, 375, 405 Cord –– dental dam stabilizing  234 –– retraction 255 Corrective phase  30 Corrosion  374–376, 378, 390, 391, 393, 402, 405, 408 Cotton roll  224, 247–254, 256–258, 260 Cotton roll isolation  256, 497, 499, 511, 546, 557, 559 Counter-opalescence  562, 567 Coupling agent  436 Coves  211, 214, 343, 363 Crack(s)  421, 424, 698, 699, 702 Cracked teeth  697–699, 702 Cracked tooth syndrome  12, 696, 697 Cracking  12, 23 Craze lines  697 Creep  375, 386, 391 Crevice  483, 499 Crevicular fluid  499 Cri dentinaire  216 Critical pH  82 Cross-link  438, 439 Crowding 12 Crown form  270, 682 Crystalline phase  681 Crystallization  374, 376, 390, 393 Cup(s)  143, 145, 405 Curing lamp  442 Curing mode  457 Curing protocol  436, 453, 457, 585 Cusp –– angle  187, 206, 207, 583 –– elongation phenomenon  197 –– incline  187, 192 –– lost  413, 426 –– restoration of  412, 415, 429, 431 –– weakened 580 Cuspal-capping 413 Cuspal coverage  413, 702 Cuspal deflection  12, 197, 438, 439, 585, 592, 604 Cuspal fracture  578 Custom-made matrix  681

709 Index

D Dappen dishes  157 Dark-curing  568, 585, 592, 628 Darkened groove  90, 97 Dead tracts  295 Decay 32 Decision-making process  33 Defense mechanisms of pulp tissue  295, 311, 313 Definitive phase  29, 30, 32 Deflection, cuspal  466, 578, 585 Deformation  198, 199 Degradation  376, 390, 407 Degree of conversion  438, 441–442, 456, 458, 459, 461 Delayed expansion  376 Delivery unit  50–53, 56, 58, 64, 68 Demineralization  78, 79, 81, 82, 84–86, 88, 89, 93, 95, 97, 99, 102, 104, 108, 119 Dens in dente  12, 13, 556 Dental arch  484, 534 Dental bleaching  681, 684 Dental dimensions  488 Dental explorer  153 Dental floss  635, 655 Dental floss ligatures  518 Dental history  2, 6, 7, 33 Dental office  50, 52, 56, 57, 65, 67, 74 Dental proportion  556 Dental separation  492, 493, 520, 583, 586, 604 Dental stone  682 Dental team  52, 53, 74 Dental whitening  14–16 Dentin –– affected 313 –– bridge  310, 320 –– color 216 –– dark color  295 –– desensitizer 307 –– firm  216, 217 –– glistening aspect  497, 498 –– hard  209, 216 –– hypersensitivity  692–695, 702 –– intertubular 188 –– leathery 216 –– matrix metalloproteinase  219, 497, 580 –– peritubular 188–190 –– permeability  308, 313 –– pink discoloration  304, 499, 538 –– primary 188 –– reactionary  85, 86, 188, 312 –– reparative  86, 188, 293, 295, 306, 307 –– replacement  187, 207, 208 –– sclerosis  295, 312, 318 –– sclerotic  85, 86, 88, 188, 189, 191, 304, 305, 314 –– scream of  312 –– secondary  188, 194, 292 –– shade  586–588, 592, 604, 622 –– soft  209, 216, 217 –– spoon  128, 129, 132, 359, 363 –– tertiary  85, 86, 188, 293, 295, 310, 315 Dentinal fluid  191 Dentin caries –– affected dentin  85 –– infected dentin  85 –– necrotic dentin  85 Dentinoenamel junction (DEJ)  191, 206, 207, 340 Dentinogenesis imperfecta  16

Dentin-pulp complex  291, 292, 294, 295, 301, 304, 305, 307, 308, 310, 312, 315, 319 Dentists  44–50, 52–58 Depth cut  414, 673, 675 Depth-limiting diamond point  675 Depth-limiting drill  422 Depth of cure  613, 618 Depth of the preparation  304, 313 Desensitizing agent  308 Detergents 219 Developmental lobes  192 Diabetes mellitus  81 Diagnosis  17, 20, 30, 40, 694, 696, 699, 702 Diagnosis of the pulp condition  295, 296, 301, 302, 323 Diagnostic –– false-negative decisions  96 –– false-positive decisions  96 –– true negative decisions  96 –– true positive decisions  96 –– wax-up 682 Diamond  125, 131, 136, 141–143, 146, 147, 149–151 Diamond dresser  143, 144 Diamond point  125, 141, 146, 149, 151, 494, 496, 500, 506, 511, 524, 551, 562, 570, 571, 573, 583, 584, 588, 621, 623, 626, 628 –– agglutinated diamonds  149 –– chemical vapor deposition (CVD)  149 Diastema(s)  12, 13, 32, 483, 492, 499, 556, 559, 669, 672 Dichroic reflector  443 Diet  78–82, 86, 90, 94, 97 Dietary advices  632 Dietary protocol  28 Digital imaging fiber-optic transillumination (DIFOTI) 103 Digital smile design  669 Direct casting  682 Direct pulp capping  301, 308, 310–312, 314, 319 Direct pulp protection  310–312 Direct technique  668 Discomfort  57, 63, 68 Discs  132, 141, 143, 144, 146 –– abrasive 572 Disease –– multifactorial 78 –– occupational 67 Disocclusion guide(s)  23, 31, 32, 393, 492, 553, 559, 569 –– anterior 668 –– canine 686 Displacement –– dental 185 –– of the restoration  360, 363, 569 Disposable applicator  592, 599 Ditch  17, 204, 206, 340, 359, 360, 628 Documentation  32, 33, 40 Dovetail lock  213, 361 Dresser 405 Durability  405, 409 –– restoration 359 Dystrophic calcification  16

E Early childhood caries  633, 639 Eccentricity 147 Eccentric load  360

C–F

Ectopic eruption  12 Edema  295, 296 Edge-to-edge occlusion  669 Education 67 Elastic deformation  198 Elastic modulus  438, 439, 441, 507, 585, 613 Elastomeric impression material  682 Elbows  46, 52, 53, 58, 67 Elderly patient  2 Electrical conductance measurements  103 Electric pulp test  299, 300 Electromagnetic spectrum  436 Embrasure(s)  384, 391, 402, 405, 531, 559, 570, 572 Emergence profile  559 Emittance  442, 447–450, 452, 453, 456, 457, 585, 618 Enamel –– caries –– dark zone  82 –– lesion body  82 –– subsurface lesion  83 –– surface zone  82, 84 –– translucent zone  82 –– hatchet 362 –– prisms  203, 204, 208, 218 –– undermined  187, 201, 207, 209 Enameloplasty  203, 650 Endodontic posts  412, 420, 425 Energy density  452, 453, 456 Energy dose  452, 453 Entry direction  492, 494, 495 Er,Cr:YSGG 161 Ergonomic(s)  44–46, 67–69, 74 Erosion  6, 8–11 Erosive tooth wear (ETW)  8, 693–695 Er:YAG  125, 161 Esthetic  15–17, 20, 21, 23–27, 30–32, 40, 184 –– analysis  484, 488, 492, 573 –– assessment 20 –– transformation 669 Etch-and-rinse adhesives  219 Etching 219 Etiology  692, 699 EVA system  147, 149 Evidence-based clinical practice  3 Excavator(s)  125, 128, 600, 604 Excursive movements  569 Exploratory probe  153, 343–344, 360, 361, 369 Extended fissure sealant  650 Extension for prevention  201, 336, 339, 340, 360 Extensive amalgam restoration  412, 415 Extracellular polysaccharide  81 Extraoral exam  2, 7, 296 Extrinsic acids  693 Extrinsic stain  14, 15, 20, 467, 492 Extrusion  200, 580, 583 Eye protection  58

F Facet 668 Fatigue  46, 49, 52, 56, 63–65, 68, 69, 199 Feathered-edge  672, 673 Feldspar  681, 683 Felt  143, 627 Fermentable carbohydrates  82 Fiber optic transillumination (FOTI)  103 Fiber post  458

Index 710

Filler –– content  439, 468, 469, 507 –– inorganic  466, 560 –– particle 456 –– ratio 439 Filling instrument  506, 524, 559 Fingers  44, 46, 58, 70, 72 Finishing  392, 393, 402, 403, 407, 409, 488, 494, 496, 506, 507, 511, 518, 520, 524, 534, 559, 568–570, 592, 608, 612, 626, 628, 629 Finishing of the enamel walls  218 Fissure  80, 82, 88, 89, 192, 201, 338, 340, 359 Fistulas 296 Fitting  683, 686 Flame shaped  393, 402 Flash  402, 497, 511 Flat area  686, 687 Flat brush  507 Flexural strength  204, 681, 683 Flowable composites  469, 507, 511, 550, 559, 648, 651 Fluorapatite  582, 637 Fluorescence  216, 473, 475, 476 Fluoridated apatite  637 Fluoridation –– local 636 –– preeruptive  636, 639 –– systemic  636, 639 Fluoride  79, 82, 86, 88, 89, 94, 119, 632, 634, 636–644, 646–648, 654, 655 –– acute lethal dose  639 –– amine  637, 639 –– gel 639 –– inorganic 636 –– organic 636 –– probably toxic dose  639 –– silver diamine  639 –– sodium 637 –– solutions 307 –– stannous 636 –– toxicology 639 Fluorosis  15, 16, 640 Food impaction  17–19 Forceps –– clamp  156, 157 –– clamp holding  232 –– Halstead hemostatic mosquito  153 –– Miller articulating paper  153 –– punch  225, 227 –– rubber dam punch  156 Forces  185, 191, 196, 198, 210 Fork-shaped bending tool  424 Four-handed dentistry  45 Fracture(s) 296 –– resistance  185, 187, 201, 426 –– toughness 681 –– longitudinal  697, 699 –– vertical root  697 Fractured cusps  697 Fractured restorations  692 Free radical  441, 458, 461 Free smooth surface  365 Frictional retention  210, 213 Friction grip (FG)  139 Frosty appearance  686 Full crown  173 Full-power curing cycle  453 Furniture  45, 52, 53, 64

G Galvanic 307 Gap(s)  406, 466, 483, 550, 569, 578, 581, 582, 628 Gear reduction contra-angle handpiece  423 Gel –– glycerin-based 592 –– oxygen blocking  592 –– point  438, 441 General principles  336 Gingiva-colored composite  511 Gingival barrier  248–250, 255, 499, 546 Gingival contour  24 Gingival displacement  682 Gingival line  23–25 Gingival margin  194, 580, 599, 621 Gingival margin trimmer  130, 131 Gingival protection instrument  683 Gingival retraction  675, 678 Gingival smile  24 Gingival sulcus  483, 497, 499, 511, 522, 531, 532, 570 Gingival zenith  489, 511 Glass(es)  54, 58 –– ceramic  681, 683 –– fiber post  538 –– fillers  466, 468 Glass ionomer cement (GIC)  307, 309, 582, 585, 586, 619, 645, 646 Glassy phase  681, 684 Glazing 683 Glutaraldehyde  308, 695 Gnarled enamel  186 Gradual curing protocol  456, 461 Grasp of hand instruments  59, 62 Grinding  131, 132, 141, 142, 145–152, 158 Groove(s)  486, 487, 562, 563, 571, 643, 646, 650, 651 –– developmental  366, 370, 392, 402 Gummy smile  23–25 Gun design syringe  513

H Habits 67–69 Half-moon margins  524 Hand instrument –– active  125, 126 –– blade  125, 127, 128, 130 –– calcium hydroxide liner placement  154 –– complementary  125, 152 –– formulas 130 –– handle 128 –– plastic filling  154 –– retraction cord packing  154 –– shank  134, 139 –– sharpening 131 Handpiece –– high-speed  134, 137–139, 150, 151, 158 –– low-speed  132, 134, 137, 139 –– oscilatory 148 –– straight  133–136, 138 Hardness  215, 216 Harmful 407 Hatchet 128–131 Head  46, 47, 49, 52–58, 67, 68, 70 Headrest  54, 56, 58 Healthy  56, 58, 68, 69, 74

Hearing damage  138 Heating 189 Heat test  299, 300 Height of curvature  17 Hidden caries  8, 201 High-copper  375, 376 High-speed handpieces  189 Hips  46, 47, 49, 70 History of the present illness  3, 33 Hoe  128, 130, 131 Holes 211 Hollenback  360, 384, 391–393, 397, 400 Hooke’s law  439 Horizontal percussion  296, 298 Horizontal slot  363, 397 Hot-pressing  682, 683 Hue  471, 472, 477 Humidity  63, 64 Hutchinson’s incisors  12, 556, 669 Hybrid composite  559 Hybrid dental ceramic  683 Hybridization  303, 304 Hybrid layer  219, 578 Hydrodynamic theory  11, 12, 294, 699 Hydrofluoric acid gel  623 Hydrophilic monomer  578 Hydroxyapatite  78, 81, 82, 119, 637, 641 Hydroxyapatite crystals  185 Hydroxyethyl methacrylate (HEMA)  308 Hyperesthetics 23 Hyperkyphosis 46 Hyperlordosis 46 Hypersensitivity 185 Hypomineralization 15–16 Hypoplasia 16 Hyposalivation  5, 28

I Iatrogenic  192, 359 Illumination  57, 62–65 Incandescent  442, 445 Incident beam angle  455, 456 Incident irradiance  451–456 Incisal edge  468, 470, 472, 473, 476, 484, 488, 492, 499, 524, 531, 534, 538, 556, 562 Incisal embrasures  488, 489 Incisal line  24, 25 Incisal reduction  688 Incisor  488, 491, 497, 553, 554, 556, 559 Inclines, cusp  339, 342 Increment(s)  469, 497, 506, 507, 511, 524, 534, 539, 559, 573, 585–587, 592, 596, 604, 613, 617, 619 Incremental technique  601 Indirect ceramic veneers  669 Indirect curing technique  457 Indirect laminates  681 Indirect pulp capping  312 Indirect pulp protection  312 Indirect restoration  581 Indirect veneer  668, 676, 681, 682 Infected dentin  312, 313 Infiltration technique  653–655, 658 Informed consent  33 Infrared  436, 442–444, 447, 448, 452, 460 Infrared band-pass filter  444 Ingot 376 Initiator 437

711 Index

Injuries  45, 65, 67 Inlay 173 Inorganic matrix  436 Insert  612, 613 Instrument(s)  50, 52, 53, 56, 57, 61, 66–69, 74, 467, 468, 490, 491, 493, 499, 507, 513, 518, 524, 534, 568–570, 573 Interdental papilla  359 Interdisciplinary 32 Interface –– adhesive 203 –– tooth-restoration  185, 194, 200 Interfacial defect  580 Interferences  583, 626 Interim restoration  682 Internal line angle(s)  347, 360, 363 –– first set  170 –– second set  170 Internal walls  203 International Organization for Standardization (ISO)  45–47, 146 Interprismatic enamel  185, 186 Interproximal carver (IPC)  393, 400 Interproximal contact(s)  17, 19, 262, 264, 270, 277, 600 Interproximal guard(s)  192, 193, 359 Interproximal space  262, 276, 277, 279, 280, 282, 359, 360, 379, 384, 393, 397, 400 Interpupillary line  23, 25 Interrod 185 Intervertebral discs  46, 47, 52, 69 Intoxication  407, 408 Intradentinal pins  212 –– cemented 421 –– friction-locked  420, 421 –– self-threading 421 Intra-oral camera  108, 110 Intraoral clinical  7 –– exam 296 Intraoral scanner  682 Intraradicular post  214 Intrinsic acid  693 Intrinsic staining  14 Inverted cone instrument  361, 369 Irradiance 585 Ischium  48, 49 Isolation  375, 378, 393, 397, 408 Isolation of the operating field  483, 493, 531 Isthmus region  208, 209

J Junctional l epithelium  194

K Kinetics  438, 453 Knees  46–48, 53, 69, 70 Knot –– double 233 –– running 233–235

L Labial embrasure  686 Laboratory 74 Lactobacillus  80, 81, 94

Laminate 689 Laser  125, 159–161, 163, 447, 695 Lateral excursive movement  583 Law of the face  687 Layering technique  441, 461, 499, 524, 585, 586, 592, 604, 612, 617, 621, 629 LED  448, 449, 451, 452, 454, 455 Left-handed  56, 70, 72 Leg  46–49, 54, 56, 57, 65 Lesion activity status  216 Leucite  681, 683 Ligature –– dental floss  233, 237, 239 –– elastic  234, 238, 246 –– o-ring 234 Light  442, 444, 449, 468–470, 472, 473, 475, 476, 479, 481, 482, 487, 488, 498, 570 –– conducting tip  612 –– overhead 57 –– pipe  443, 444 –– reflection measurement  108 –– tip  445, 450, 451, 454 Light-activated  436–438, 440, 441, 448, 450 Light-curing  436, 437, 442–445, 448–456, 458, 460, 461, 585, 588, 592, 593, 596, 597, 604, 612, 613, 618, 626, 628 –– protocol 453 –– unit  436, 443, 444, 455, 460 Light-emitting diode  442, 448, 449 Light guide  442, 444–447, 452, 453, 455–457, 461 Light guide free curing unit  455 Line angle –– external 170 –– internal 170 –– round 208 –– sharp 198 Liner  307–311, 314 –– low elastic modulus  585 Lip line  24, 671, 672 Lithium disilicate  683 Load –– compression 198 –– shear 198 –– tensile 198 Lobes –– dentin  473, 563 –– developmental  473, 484, 487, 571 Local anesthetic test  300 Locks  210, 215 Long-inverted cone  338, 340, 347 Lost wax technique  683 Loupe  157, 158 Low fusing compound  264, 431, 432, 499, 546, 548 Lubricating gel, glycerin based  405 Lucirin TPO  438 Lumbar region  47, 52, 65

M Macroesthetics 23 Macrofilled composite  467 Macrotextures  486, 487 Magnifier 157 Maintenance phase  29, 30, 40 Mamelons of dentin  473, 535

F–M

Margin –– cavosurface 172 –– preparation 168 Marginal degradation  187, 204 Marginal ridge(s)  187, 203, 208, 494, 572, 584, 585, 600, 604, 605, 612, 626 Marginal staining  20, 21 Marginal trimming  187, 218 Masking agent  669, 679 Masticatory stress  336 Matrix  578, 580, 584, 586, 600, 601, 604, 612, 613, 619, 626, 629, 669, 681, 682, 685 –– band  336, 362, 363, 493, 500 –– Barton 285 –– boomerang-shape 263 –– cervical  269, 271, 281 –– circumferential  264, 288 –– custom made  264, 266, 283, 384, 392 –– metallic  263, 264, 268 –– retainer  156, 336, 359, 604 –– retainerless  265, 269, 285 –– riveted  262, 285 –– sectional  264, 265 –– shell 270 –– spot-welded  284–285, 394 –– S-shaped  285, 397 –– T 378 –– universal  270, 284, 285, 378, 394, 397 –– welded 378 –– window  285, 397, 398 Maximum intercuspation (MIC)  200, 393, 580, 583 Mechanical principles  220 Medical history  2, 4, 5, 7 Medical interview  3, 4, 40 Medication  2, 4–6, 9, 28 Megafiller 612 Mercury  340, 402, 407–409 Mesenchymal cells  191, 294, 312 Metalloproteinases (MMP)  219, 307, 313 Metamerism 479 Microbiota  78–81, 89, 93, 94 Microcrack  438, 578, 626, 628, 699 Microdontia  12, 556, 669 Microesthetics  23, 488 Microfilled composite  467–469, 585 Microhardness 187 Microhybrid composite  468, 585 Microleakage  20, 308, 309, 312, 325, 483, 520, 569, 578, 585, 592 Micromechanical interlocking  497 Micromechanical retention  499, 683, 685 Micromotor  133, 134, 138 Microorganisms  305–307, 310, 325 Microscope, dental operating  158 Microtexture 486 Migration, tooth  199 Miller forceps  626 Mineral trioxide aggregate (MTA)  310 Miniesthetics 23 Minimally invasive dentistry  632, 653 Minimally invasive preparation  632, 650 Mirror  47, 56, 58, 62, 68, 69 –– first-surface 152 –– second-surface 152 Mobility test  297 Mock-up  556, 669, 678 Molar incisor hypomineralization (MIH)  658

Index 712

Monochromatic 683 Monolithic 683 Monomers  436–438, 441, 456, 458 Mortar  385, 386 Mosquito forceps  384 Mottled teeth  636 Mounted stone(s)  142, 143, 569, 570 Mouth  46, 52–57, 62 Mouthrinse 639 Movement(s) –– excursive  583, 626 –– lateral 583 –– protrusive 583 Mulberry molar  12 Multi-bladed bur(s)  402, 569, 570 Muscles  44–46, 49, 59, 64, 68, 72 Mutans  80, 81, 92, 94

N Nanofilled composite  585 Nanohybrid composite  468, 469, 619 Nano-hydroxyapatite 695 Narrow-spectrum 448 Natural retention  210–212, 214, 425 Nd:YAG  125, 161, 163 Near-infrared light transillumination (NILT)  103 Necrosis 85 Needle shaped diamond point  686 Nerve desensitization  695 Nibs  152, 154, 155 Noise  45, 63, 158 Nomenclature  168, 172 Non-adhesive restorations  185, 187, 203 Non-carious lesion(s)  2, 8, 9, 483, 499, 573 Non-demineralizing cleaning agents  306 Non-invasive measures  185 Non-selective removal  216 Nonstick composite filling instrument  587, 621 Non-supporting cusp  413 Nutrition  632, 633 Nutrition habits  632

O Objective exam  7 Oblique crack  196 Oblique increment  604, 612, 617 Oblique ridge  197, 343, 344 Occlusal adjustment  626 Occlusal frontal line  23, 24 Occlusal frontal plane  23 Occlusal interrelationship  413 Occlusal load(s)  347, 360, 375, 393, 412, 415, 580, 581, 584, 585 Occlusal plane  27, 342, 344, 347, 360, 363 Occlusal splint(s)  23, 554–556 Occlusal stamp  593, 596, 597 Occlusion  556, 568 –– centric  583, 626 –– of dentinal tubules  695 –– dynamic 583 –– static 583 Ocular hazards  460 Odontoblast  291, 293–295 Odontoblastic layer  191 Odontoblast-like cells  293, 294

Office  50, 65, 69 Older patients  5, 6 Onlay 173 Opacity  469, 470 Opalescence 472–476 Opalescent halo  473 Opaque  469, 470, 472, 484, 506, 507, 511, 535, 562 Opaque halo  484, 535, 538, 563 Opening of the cavity  201, 207 Operating field  224, 234, 244, 246–248, 250, 252, 260 Optical density  461 Optical illusion  686 Oral cavity  53, 54, 57, 58, 69 Oral environment stabilization  112 Oral health  200 –– impact profile  694 –– records  32, 33 Oral hygiene  632–635, 639–644, 646, 652, 655 –– habits 632 Organically modified ceramic  618 Organic matrix  436, 439, 466–468, 483 Ormocer 618 Orthodontic extrusion  539, 551 Orthostatic  45, 46 Outline –– form  200, 204, 207, 209, 344, 359, 366, 671 –– of the preparation  493 Overbite  553, 554 Overcontour  8, 17, 397 Over finish  402 Overhang(s)  262, 263, 280, 282, 378, 379, 384, 393, 559, 568–570, 573, 599, 626 Overlapped incisal edge preparation  673, 676 Overlay 173 Overtrituration 386 Oxalate 695 Oygen blocking gel  511 Oxygen inhibition layer  441, 592 Ozone 642

P Packable 613 Packing instrument, retraction cord  499 Pain –– diffuse 308 –– odontogenic 301 –– rebound  697, 699, 701 –– referred 300 –– reflex 301 –– spontaneous  301, 302, 314 –– throbbing  301, 303 Palatal chamfer  673, 676, 684 Palpation  296, 297 Parafunctional activities  483 Parafunctional habits  11, 23 Parafunctional oral habit  669 Parallel-walled light guide  455 Partly sintered blocs  683 Patient  44, 46, 47, 52–54, 56, 57 Peg-shaped teeth  499, 669 Perforation  417, 421, 422, 425, 428 Performance  49, 56, 57, 63 Periapical abscess  296 Periapical alterations  296 Periapical infection  298 Periapical inflammation  301, 303 Perikymata  487, 571

Periodont  6–8, 32 Periodontal examination  7, 8 Periodontal health  194, 200 Periodontal probing  297 Peripheral depth cut  673, 675 Pestle 385 Phenyl-propanedione  437, 443 Phosphoric acid  219, 305, 306, 313 –– gel  497–499, 506 Photochemical damage  460 Photodynamic therapy  642 Photomechanic ablation  161 Piezoelectric 148 Piggyback wedging technique  282 Pink discoloration  585 –– of dentin  304 Pins 210 –– wrench 422 Pioneer bacteria  81 Pit  89, 90, 98, 106, 115 Pit and fissures  174 –– sealant  336, 642 Plane –– buccolingual  168, 169 –– delimitation  168, 169 –– dental 168 –– frontal 168 –– horizontal  168, 172 –– mesiodistal 168 –– occlusal 169 –– sagittal 168 –– section  168, 169 Plaque –– chemical control of  632, 633 –– index 28 –– mechanical control of  632, 634 Plasma arch curing units (PAC)  445 Plastic deformation  198 Plier  152, 157 –– riveting 157 Pluggers 154 Plunging ball technique  612 Point(s)  125, 141, 143, 146, 149–151, 388–390, 397, 402, 405 –– angle 412 Polishing  374, 376, 393, 398, 402, 405, 407, 468, 469, 483, 488, 507, 511, 528, 559, 567, 568, 570, 571, 573, 613, 626–628 Polish retention  469 Polyacrylic acid  306, 309, 313, 586 Polychromatic restoration  534 Polychromatism 471 Polyether 682 Polymer 436–438 Polymeric chain  437, 439 Polymerization  437–442, 444, 447, 453, 455–459, 461, 586, 587, 592, 604, 612, 613, 618, 628 –– shrinkage  438, 439 –– supplemental 626 Polypharmacy  5, 6 Polywave 449 Porcelain 683 Position  44–47, 49, 50, 52–54, 56–58, 61, 65–68, 70, 72, 74 Positioning jig  546 Post-bonding 628 Post-eruptive enamel maturation  79, 88, 637, 644 Post-gel phase  438

713 Index

Post(s) 210 –– intraradicular 553 Postoperative sensitivity  302, 303, 466, 573, 628, 692, 694, 699 Post-polymerization 438 Posture  44–49, 52, 54–59, 65, 67–69, 74 Potassium salts  695 Practice  44, 45, 65, 67, 74 Precapsulated 385 Preclinical  45, 62, 68, 74 Pre-contoured matrix  580 Precrystallized state  683 Predentin  291, 292 Predisposing factors  699 Pre-gel  438, 441, 448, 456 –– phase 585 Pre-odontoblasts 294 Preparation  585–587, 599, 600, 604, 613, 618, 619, 621, 622, 629, 683, 686, 689 –– cavity  168, 172 –– components  168, 170 –– deep 174 –– guide  670, 671 –– horizontal slot  584 –– large size  350 –– medium 174 –– medium-size 350 –– prosthetic 173 –– shallow 174 –– small size  344 –– therapeutic 173 –– tooth  174–176, 178, 182, 467, 482, 492, 493 –– very deep  174 Prepolymerized ball technique  612 Pre-procedural mouth rinsing  499 Pre-reacted glass-ionomer filler  582 Prevention –– primary  632, 633, 642 –– secondary 632 –– tertiary 632 Preventive measure  632, 642–644 Preventive procedures  336 Preventive resin restorations  650 Primary dentin  295 Primary prevention  81 Principle of gradation  27 Prismless enamel  185, 186, 495, 646, 648 Prisms  185–187, 189, 218 Probiotics 640 Procedure  45–47, 52–54, 56, 57, 59, 61, 67, 68 Prophy-jet device  492 Prophylactic antibiotics  5 Prophylaxis  499, 546, 583, 621 Proportion gauge  490 Protective materials  307, 312, 319 Protrusive movement  626 Provisional restoration  682, 683, 689 Proximal box preparation  350 Pulp  294, 295 –– accidental exposure of  200 –– aging process  295 –– capping 295 –– condition assessment  291, 296 –– curettage  319, 320 –– exposure  301, 302, 310, 312, 320 –– horn 585 –– inflammation  295, 319 –– microexposures 585

–– protection  309, 312 –– repair  310, 311 –– sensitivity testing  319, 320, 322 –– vitality  294, 295, 298, 307, 312, 319, 320, 325 Pulpal alterations, origins of  291, 302, 328 Pulpal chamber  200 Pulpal condition  200 Pulpal diseases  12 Pulpal exposure(s)  174, 304, 307, 310, 312, 317 Pulpal inflammation  295, 301, 302 Pulpal pressure  295 Pulpal wall  172 Pulpectomy 327 Pulpitis –– acute irreversible  301, 302 –– acute reversible  301 –– hyperplastic chronicle  301, 302 –– ulcerative chronic  301 Pulpless  420, 425 Pulpotomy  301, 310, 319, 320, 323, 325 Pulse-delay protocol  456 Pumice 143 Punch  225, 228, 240, 242 Pupal provocation tests  12

Q Quality of life  692, 694 Quantitative light-induced fluorescence (QLF)  105, 106 Quartz-tungsten-halogen (QTH)  442

R Radiant emittance  442, 446–448, 450–452, 454 Radiant exitance  450 Radiant power incident  451 Radiographic analysis  200 Radiographic examination  98, 100, 101, 296, 300, 301, 304 Radiometer 452 Ramp 585 Ramp cycle  457 Reattachment of fractured tooth  546 Rebonding  573, 628 Reciprocating movement device  148 Recurrent carious lesion  578 Re-dentistry 16 Reduction guide  670 Reflective wedge  440, 441 Refractory cast  682 Refrigeration  134, 135, 140–142, 147, 163 Reinforce  578, 580, 581, 584 Reinforcement 187 Reinforcing structures  197 Relative air humidity  64 Remaining tooth structure  199, 203, 208, 220, 412, 415, 417, 421, 422, 425, 426, 466, 477, 492, 496, 523, 531, 546, 551, 555–556, 578, 580, 584, 604, 613, 621, 626 Remineralization  78, 79, 81, 82 Removal of the remaining carious tissue  361, 363, 370 Repetitive restorative cycle  29, 30, 184 Repetitive strain  45, 65 Resin-based sealant  645, 646, 648 Resin cement  539, 546, 548, 550

M–R

Resin infiltration technique  497 Resin modified GIC (RMGIC)  309, 586 Resinous monomers  466 Resistance  412, 415, 419, 425, 431 Resistance form  203, 342, 360, 363 Rest  48, 52, 61, 62, 64, 65, 67, 74 Restoration technique  5–12, 16–21, 23, 28–32, 283–285 –– direct 185 –– extraoral 185 –– indirect 184 –– intraoral 185 –– semi-direct  185, 211 Retainer –– disposable 264 –– integrated 264 –– Ivory 270 –– matrix  270, 272–274, 280, 284, 286 –– Siqveland  157, 270, 273, 274 –– Tofflemire  157, 263, 270–273, 336, 377, 378, 604 –– universal  270, 284, 285, 317, 378, 394, 397, 398, 426, 427, 429 Retention 412 –– additional  343, 344 –– artificial 210 –– axial offset  415 –– cove  414, 415 –– form  210, 412, 426 –– locks  348, 361, 415 –– micromechanical 219 –– slot  416, 417 –– undercuts 415 Retraction clamp  499, 508 Retraction cord  397, 499, 513, 557, 679, 681, 682 –– packing instrument  397 Reverse curve  360 –– Hollenback’s 208 Right-handed  52, 53, 56 Risk assessment  7, 28 Risk communication  33 Riveted matrix  427 Riveting plier  428 Rods  185, 187 Room  50, 52, 57, 63, 68 Root canal treatment  699, 702 Root furcation  417, 422 Rotary instrument –– abrasive  125, 131, 140 –– cutting  125, 126 –– head  133, 135, 141, 149 –– neck 139 –– shank  127, 130, 135, 139, 147 Rotation speed –– axial 146 –– cutting  139, 146, 147 –– peripheral 146 Roughness  140, 143 Round angles  342 Round bur  584, 614 Round diamond point  344, 359, 368 Round internal line angles  342, 344 Rubber dam  224–227, 233–242, 244–250, 252, 255, 260 –– frame 225 –– isolation  479, 482, 493, 497, 499, 500, 518, 546, 562 Rubber sheet  225–227, 234, 237–242, 244, 246, 248, 493, 518

Index 714

S Safety –– glasses  147, 163, 165 –– procedures 147 Saliva –– absorbers 224 –– acquired pellicle  81 –– buffering capacity  81, 94 –– clearance 81 –– ejectors  224, 250, 251, 256 –– hygoformic 250–252 –– flux 80–82 Salivary glands’ ducts  250 Sandblasting  626, 628, 685 Saphenous vein  49 Saw 626 Scaffold 312 Scalpel blade  511, 534, 569 Schultz 397 Scissor 156 Sclerotic dentin  312, 314, 496, 562, 694 Scoliosis  46, 52, 65 Screwdriver-shaped incisors  12 Sculpture 391–393 Sealers 307 Secondary caries  185, 219, 303, 307, 466, 573, 582, 599, 600 –– lesions 20 Sectional matrix  600, 619, 629 Selective bonding  585, 586 Selective removal  216, 217 Self-cure 437 Self-etching adhesive  219, 303, 313, 498 Self-retentive preparation  359 Self-sealing 374 Sensitivity  694, 699 –– scale 694 –– thermal testing  492 Separation –– ring  583, 600, 601, 604, 621 –– technique 492 –– tooth  78–80, 82, 100, 109 Serrated strip  626, 627 Setting time  377, 389, 390 Shade guide  477, 479–481, 511 Shade selection  477, 479, 481, 496, 513, 546, 556, 573, 583 Shade tabs  477, 481 Shadows  57, 58, 64 Shared decision-making  2, 29, 31, 33, 40 Shrinkage  386, 466, 468, 569, 573, 585, 586, 592, 612, 613, 617, 618 Shrinkage stress  439, 441, 448, 457, 461, 578, 581, 587, 613, 617, 618 Sight’s angle  672 Silane coupling agent  436, 466, 668, 683, 684, 686 Silanized surface  685, 686 Silicon carbide (Sic)  131, 145 –– brush 627 Silicone index  534, 538, 559 Silver  374, 375 Simple preparation  338 Simulator phantom  336 Sintering 682 Site 177–179

–– site 1  338, 339 –– site 2  350 –– site 3  363, 365 Size 177–179 –– size 1  340, 344, 350 –– size 2  340 –– size 3  344, 350 Sjögren’s syndrome  81 Sleeve technique  246, 248 Slots 211 Small preparations  370 Smear layer  218, 219, 303, 305, 306, 313 Smear plugs  218 Smile esthetics  484 Smile line  24 Smoking habit  483 Smooth surfaces  172–174, 177 Smooth walls  203 Sodium fluoride  219 Sodium lauryl sulfate (SLS)  219, 306 Sodium monofluorophosphate  637 Soft start  585 –– protocol 457 Sonic 148–150 Sound 63 Spanish white  143 Spatula  125, 152, 153 Spectral absorption  438, 451 Spectral output  442 Spectral power  442 Spherical particles  375, 376, 385 Spiral wheels  143, 144, 627 Split teeth  697 Spoon excavator  128, 584, 600 Spot-welding device  428 Spray of air-water  189 S-shaped curve  360 Staining 683 Stainless steel  126, 141, 145 Stamp  238, 239, 241 Standard light guide  455 Stannous fluoride  695 Stem cells  310 Steps  578, 585, 586, 626 –– cycle 457 –– of tooth preparation  200 Stepwise excavation  217, 306, 312, 314, 318, 319 Sternum bone  56 Stimulated emission of radiation  447 Stimulus –– cold thermal  699 –– evaporative 692 –– osmotic  692, 694 –– tactile 692 –– thermal  692, 694, 699 Stool  46, 48–50, 52, 54, 56, 57, 67, 69 Strain 197 Stratified layering technique  499 Strength  375, 376, 386, 389–391, 393 Streptococcus  80, 81, 94 –– S. mutans  633, 642 Stress –– compressive 198 –– concentration 198–200 –– distribution 360 –– shearing 198

–– tensile 198 Stress-absorbing layer  585, 612 Strip, abrasive  511, 524, 570 Strontium 695 Strontiumapatite 582 Students  46, 67, 68, 74 Subjective exam  3, 7 Sucrose  78, 80, 81 Suction  52, 58, 63, 224, 247–253, 257, 260 Sugar alcohol  633, 640 Sugars 632–634 Supine  53, 54, 58 Supporting cusps  209, 413, 425 Surface conditioning  683 Surface pre-reacted glass-ionomer (S-PRG)  582 Surface pretreatment  689 Surface roughness  467, 468, 482 Surfaces (tooth)  46, 47, 56 Surface sealing  573, 588, 628 Surface texture  486 Surgical crown lengthening  12, 20, 25 Symptoms  696, 697, 699, 702 Syringes  493, 506, 513 Systemic diseases  2, 4, 28, 30 Systemic phase  29, 30

T Tactile feedback  216 Tattoo 409 T-band  262, 285, 426, 427 Technique –– stratified layering  586 –– wedge alternation  586, 612 Teeth clenching  210 Temperature  44, 45, 63, 64 Templates  238, 239 Temporomandibular joint (TMJ)  7, 23 Tensile strength  412 Terminology  168, 182 Tertiary amine  437 Test cavity preparation  492 Thermal 64 Thermal expansion coefficients  210 Thermoplastic material  681 3D digital impression  682 3D model  682 3D printing  669 Three-wheeled diamond depth cutter  675, 676 Thumping action  507 Tin  374, 375, 405 Tint(s)  507, 538, 562, 588, 592, 622, 679 Tofflemire  336, 378 Tongue retractor  251, 254, 255 Tooth  46, 47, 57, 61, 62 –– contour 185 –– face 686 –– fractures  6, 12 –– function 185 –– mobility testing  297 –– preparation  184, 185, 189, 194, 196, 291, 295, 302, 304–307, 319, 323 –– separation 583 Toothbrush  634, 635, 650 –– powered 635 –– sonic 635

715 Index

Toothpaste  636, 639, 640, 642, 650 Torque 147 Torso  45, 46, 54, 56, 69, 70 Total bonding  585 Total energy concept  452 Total-etch adhesive system  497, 498 Training model  336 Transforming growth factor beta (TGF-β) 311 Transillumination  297, 298 Transitional line angle  686, 687 Translucent  468–470, 472, 473, 475, 484, 485, 488, 499, 507, 551 Transparent strip crowns  270, 271 Transposition  12, 13 Trans-surgical restoration  538, 546 Tray  53, 56 Trayless impression  669, 682 Treatment  44, 50, 54, 56, 63–69, 74 Treatment plan  2, 7, 8, 16, 22, 29, 30 Triangular fossae  361 Trimmer, gingival margin  345, 349, 360–362 Trituration  385, 389, 391 Try-in procedure  683 Tubular sclerosis  295 Tungsten carbide  126, 131, 139, 143 Turbine  125, 132, 133, 137, 138, 147 Turbo light guide  455 Tweezer  128, 153 Twist drill  421, 422

U Ultrasonic  125, 132, 148, 150, 151 Ultrasound 148–151 Ultraviolet (UV) light  475 –– radiation 460 Umbrella effect  309, 518 Unbonded wall  585, 586 Under-contour 397 Under finish  402 Undermined enamel  84, 97, 187, 204, 208, 338, 339, 342, 344, 349, 366 Under trituration  385, 389 Uniform curing cycle  453 Upper lip curvature  24–26 Urea 641 Urgent phase  30

V Vacuum thermoforming machine  681 Value  471, 473, 477, 480, 491, 498 Vapor 407 Varicose veins  47, 65 Varnish(es)  309, 695 Vascular changes  299 Vasoconstrictors solutions  255 Veneer  681–683, 686, 688 Vertical percussion  296 Vertical slot preparation  350, 359, 361 Vertical walls  415, 431 Viewing perspective  672 Viscosity  467, 469, 507, 513, 515 Visible light  460, 461 Vision  152, 157 –– direct  52–54, 56, 58, 62 –– indirect  56, 58, 62 Visual examination  96, 98 Vitreous ceramic  623 Volumetric shrinkage  439

W Wall(s) –– axial  168, 169, 172, 347, 361, 363, 368, 370 –– buccal  169, 172 –– convergence of  342, 360 –– distal 169 –– external  170, 172 –– gingival  172, 347, 359–363, 368 –– horizontal surrounding  170 –– internal  170, 172 –– labial 175 –– lingual  169, 172 –– mesial  169, 172 –– pulpal  170, 172, 342, 347, 350 –– sub-pulpal 172 –– vertical surrounding  170, 340, 342 Wand-style design unit  455 Water sorption  466, 518, 569 Wax-up  534, 669 Weakened cusps  413, 431 Weak point  422 Wear –– facet  23, 492

–– resistance 628 –– three-body 613 –– two-body 580 Wedge(s) –– alternation technique  586, 604 –– curved 278 –– effect  196, 198 –– reflective 586 –– rigid  153, 263, 276, 279, 378, 440, 441 –– wedging 282 –– wooden  109, 149, 153, 195, 276–278, 285, 317, 336, 359, 363, 377, 379, 397, 429, 493, 584, 586, 700 Wedging, preoperative  583, 600 White light  436, 442, 443, 446 Whitening 14–16 White spot(s)  588 –– lesion  83–86, 97, 98, 100, 105, 638, 648, 652, 655, 658 Width-to-length ratio  488–490, 556 Window 65 Window preparation  672 Working areas  53, 64 Working field  250 Work-related musculoskeletal disorders (WMSD)  44, 45, 65, 74 Wrap preparation  672, 676

X Xenon plasma  442 Xylitol  633, 634, 640, 642

Y Y-TZP zirconia  682

Z Zinc –– oxide 143 –– phosphate 307 –– polycarboxylate 307 Zinc oxide-eugenol cements  308 Zirconia, high-translucent  683 Zirconia-reinforced glass ceramic  682, 683 Zone  45, 52, 53, 58

S–Z