Comprehensive Esthetic Dentistry [1 ed.] 1850972788, 9781850972785

Table of contents :
Title
Copyright
Dedication
Contents
Foreword
Acknowledgments
Preface
Authors
I. Esthetic Dentistry in the Modern Dental Practice
1.1 Esthetic dentistry as a specific profile in dental practice management
1.2 Interdisciplinary communication and relationship
1.3 The relationship between the esthetic dental clinic and the laboratory and dental technician
II. General Principles in Dental and Dentofacial Esthetics
2.1 Examination in esthetic dentistry
2.2 Dentofacial relations
2.3 Esthetics of the dental arches
2.4 Dental esthetics
2.5 Optical properties of dental structures
2.6 Gingival esthetics
III. The Photographic Examination
3.1 Fundamentals of digital dental photography
3.2 Intraoral photography
IV. Dentist–Patient Communication During Esthetic Analysis Integrating Provisional Esthetic Rehabilitation in the Treatment Plan
4.1 Dentist-patient communication during esthetic analysis
4.2 Integrating provisional esthetic rehabilitation in the treatment plan
V. Ceramics Used in Esthetic Restorations
5.1 What is dental ceramic?
5.2 Ceramics used in dentistry
VI. Ultraconservative Dentistry
6.1 Modern esthetic dentistry
6.2 Function and esthetics
VII. Adhesive Techniques in Esthetic Dentistry
7.1 Basic aspects
7.2 Adhesion to hard dental tissues
7.3 Adhesion to ceramic
7.4 Conclusion
VIII. Tooth Discoloration
8.1 Vital tooth discoloration
8.2 Non-vital tooth discoloration
IX. Esthetic Restoration of Anterior Teeth
9.1 Direct restorations
9.2 Porcelain laminate veneers
9.3 All-ceramic crowns
9.4 The customized abutment: technique, material
X. Esthetic Restoration of Posterior Teeth
10.1 Direct restorations
10.2 Indirect restorations
10.3 All-ceramic crowns
XI. Luting Protocol for All-Ceramic Restorations
11.1 Choice of the resin cement
11.2 Examination of all-ceramic restorations
11.3 Conditioning of the dental and ceramic surfaces
11.4 Luting the ceramic restorations
11.5 Examination of occlusal relations: special considerations
XII. In-Office Dental Cad/Cam Technology
12.1 System description
12.2 Clinical indications / types of restorations
12.3 The esthetics of in-office CAD/CAM restorations
12.4 Materials used in chairside CAD/CAM technology
XIII. Dental Implants Placed in the Esthetic Zone
XIV. Soft Tissue Management for An Esthetic Aspect in Implant Dentistry
XV. Esthetic Strategies in Orthodontics
15.1 Current esthetic considerations in orthodontics
15.2 Esthetic therapeutic options in orthodontics
Index

Citation preview

Comprehensive ESTHETIC Dentistry FLORIN LĂZĂRESCU, Editor

A CIP record for this book is available from the British Library. ISBN: 978-3-86867-294-7 (ebook) 978-1-85097-278-5 (print)

Quintessence Publishing Co Ltd Grafton Road, New Malden, Surrey KT3 3AB Great Britain www.quintpub.co.uk Copyright © 2015 Quintessence Publishing Co Ltd Original book title: Incursiune în Estetica Dentară Copyright © 2013 SSER (Societatea de Stomatologie Estetică din România) All rights reserved. This book or any part thereof may not be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, or otherwise, without prior written permission of the publisher. Translation: SSER (Societatea de Stomatologie Estetică din România) Editing: Quintessence Publishing Co Ltd, London Index: Indexing Specialists (UK) Ltd Production: Quintessenz Verlags-GmbH, Berlin, Germany

Comprehensive ESTHETIC Dentistry

Dedicated to excellence in esthetic dentistry

Contents FOREWORD ACKNOWLEDGMENTS PREFACE AUTHORS I. ESTHETIC DENTISTRY IN THE MODERN DENTAL PRACTICE 1.1 Esthetic dentistry as a specific profile in dental practice management 1.2 Interdisciplinary communication and relationship 1.3 The relationship between the esthetic dental clinic and the laboratory and dental technician II. GENERAL PRINCIPLES IN DENTAL AND DENTOFACIAL ESTHETICS 2.1 Examination in esthetic dentistry 2.2 Dentofacial relations 2.3 Esthetics of the dental arches 2.4 Dental esthetics 2.5 Optical properties of dental structures 2.6 Gingival esthetics III. THE PHOTOGRAPHIC EXAMINATION 3.1 Fundamentals of digital dental photography 3.2 Intraoral photography IV. DENTIST–PATIENT COMMUNICATION DURING ESTHETIC ANALYSIS INTEGRATING PROVISIONAL ESTHETIC REHABILITATION IN THE TREATMENT PLAN 4.1 Dentist-patient communication during esthetic analysis 4.2 Integrating provisional esthetic rehabilitation in the treatment plan V. CERAMICS USED IN ESTHETIC RESTORATIONS 5.1 What is dental ceramic? 5.2 Ceramics used in dentistry VI. ULTRACONSERVATIVE DENTISTRY 6.1 Modern esthetic dentistry 6.2 Function and esthetics VII. ADHESIVE TECHNIQUES IN ESTHETIC DENTISTRY

7.1 Basic aspects 7.2 Adhesion to hard dental tissues 7.3 Adhesion to ceramic 7.4 Conclusion VIII. TOOTH DISCOLORATION 8.1 Vital tooth discoloration 8.2 Non-vital tooth discoloration IX. ESTHETIC RESTORATION OF ANTERIOR TEETH 9.1 Direct restorations 9.2 Porcelain laminate veneers 9.3 All-ceramic crowns 9.4 The customized abutment: technique, material X. ESTHETIC RESTORATION OF POSTERIOR TEETH 10.1 Direct restorations 10.2 Indirect restorations 10.3 All-ceramic crowns XI. LUTING PROTOCOL FOR ALL-CERAMIC RESTORATIONS 11.1 Choice of the resin cement 11.2 Examination of all-ceramic restorations 11.3 Conditioning of the dental and ceramic surfaces 11.4 Luting the ceramic restorations 11.5 Examination of occlusal relations: special considerations XII. IN-OFFICE DENTAL CAD/CAM TECHNOLOGY 12.1 System description 12.2 Clinical indications / types of restorations 12.3 The esthetics of in-office CAD/CAM restorations 12.4 Materials used in chairside CAD/CAM technology XIII. DENTAL IMPLANTS PLACED IN THE ESTHETIC ZONE XIV. SOFT TISSUE MANAGEMENT FOR AN ESTHETIC ASPECT IN IMPLANT DENTISTRY XV. ESTHETIC STRATEGIES IN ORTHODONTICS 15.1 Current esthetic considerations in orthodontics 15.2 Esthetic therapeutic options in orthodontics INDEX

Foreword

In our modern society, the value of a smile is becoming increasingly important. Smiling is one of our most powerful communication tools and can influence people’s first impressions significantly. It has a fundamental impact, not only on esthetics, but also on facial expressions, masticatory function, phonetics, and verbal expression. A healthy smile showing bright white teeth represents a combination of the perception of “beauty” and “health.” A common request from patients all over the world nowadays is for dental treatments that optimize esthetics and function in order to help them enhance their self-esteem and improve their professional and personal relationships. The challenge for the modern dentist is to balance the esthetic and functional objectives, and seek to achieve the best result through minimally invasive dental procedures that respect the biological parameters. The authors of this book have made a valuable contribution to our profession by putting together, in a clear, efficient, understandable, and logical way, all the concepts related to dental esthetics, explaining them from both an academic and a practical point of view. The entire dental community will benefit greatly from the contents of this book. Mauro Fradeani, MD, DDS

Acknowledgments

I could not have imagined, a decade ago, that the Romanian Society of Esthetic Dentistry would have reached such a high standing and be so widely appreciated. Through our activity over the 10 years of our existence, we have succeeded in putting together, step by step, a solid organization, whose anniversary we are now celebrating in a distinctive way. The motto describing us is associated with the name of our society and is meant to be a constant reminder of our duty: “Dedicated to excellence in esthetic dentistry.” Our entire activity has revolved around this motto. Everything we have undertaken, from the organization of conferences and courses, to editing books, guidelines, newspapers, or special journals, to setting up campaigns or press conferences, has been related to the promotion of the values of esthetics in dental medicine. This book represents the pinnacle of the work done by the Romanian Society of Esthetic Dentistry. It is a great achievement; the result of passion, knowledge, skill, dedication, and days and nights of hard work. I coordinated a team of extraordinary authors, who placed quality above all, and who aimed to share their knowledge, accumulated through years of work and study. I wish to thank all the authors, as well as all those involved in producing this book. This English edition follows a Romanian edition of 10,000 published and distributed copies, which represents a solid foundation for the education of Romanian dentists in the field of esthetic dentistry. This publication represents the first Romanian book published in English by the prestigious Quintessence Publishing, and this is both a great honor and a great responsibility. I would like to express my gratitude to Dr George Freedman and Dr Mauro Fradeani, as well as other true leaders in esthetic dentistry, for their friendship and continuous support. Many thanks to Ovidiu Tabacaru, who helped me with the photographs and figures, and who succeeded in setting such a high standard for the imagery in this book. And finally, a very special thank you to my parents, who taught me the moral values and opened up for me the path to knowledge, then helped me to remain straight on it, always looking ahead. And, of course, many thanks to my “girls”, Magda and Alexandra, from whom I stole big chunks of dedicated time.

Florin Lăzărescu, DMD Comprehensive Esthetic Dentistry

Preface The idea of this book appeared five years ago, when we undertook the task of publishing a medical specialty book with a print run of 10,000 copies to be distributed throughout Romania. The budget for producing so many copies of a book is huge, and only by accessing nonrefundable co-financing was this project possible. The success of the Romanian edition propelled us into a partnership with the prestigious Quintessence Publishing, the English version being, in accordance with the wishes of ourselves and the editors, the first in a series of translations from various national editions. The content covers the entire range of esthetic dentistry, including all the information a dental surgeon would require to be able to practice esthetic dentistry on a daily basis. In choosing the co-authors, we intended maintaining a balance between academics – who are implicitly highly professional when writing for their specialty, and whose experience is extremely valuable – and practitioners, who have a rich store of case records, and who have been trained in international centers by top specialists. Their contribution offers a fresh and clear outlook, interesting cases, and a straightforward writing style acquired through their daily activity in the dental office. The book mainly addresses dental practitioners who want to improve their work and put a beautiful smile on their patients’ faces as a guarantee of quality. By integrating the information in this book into your daily practice, you can become a dentist oriented toward dental esthetics. We are also sure that even the more experienced among you, with vast experience in esthetic dentistry, will be able to find useful information that will help improve your daily work. The book is composed of 15 chapters, divided into two parts by an invisible line. The first part includes information and data that lay a solid foundation for the clinical activities described in the second part. Thus, the first eight chapters comprise introductory elements and general principles of dental and dentofacial esthetics, such as photographic examination, communication with the patient in the esthetic assessment, integration of the provisional esthetic rehabilitation into the therapeutic plan, materials used in esthetic restorations, minimally invasive procedures in esthetic dentistry, principles of adhesion to particular dental structures, and tooth discoloration. Chapter IX to XV cover the practical aspects of esthetic dentistry, such as the esthetic restorations of the anterior and lateral teeth, the protocol for adhesive fixations in esthetic restorations, CAD/CAM systems, and techniques in the dental office. The final three chapters introduce a modern, interdisciplinary, prosthetic-orthodonticperiodontal approach, consisting of complex cases that require teamwork for a successful outcome. We conclude by wishing you success in your professional activity, and wonderful smiles on the faces of all your patients.

The authors

Authors

Dr Camelia Alb is Associate Professor in the Department of Propedeutics and Dentofacial Esthetics, Faculty of Dentistry, University of Medicine, Iuliu Haţieganu Cluj, and a specialist in orthodontics. She has participated in and directed many research projects and has co-authored five books and over 30 articles published in national and international journals indexed in the Web of Science. She is a member of many professional associations, including IADR, ESCD, EOS, SSER, RSB, and SCAD. She has presented numerous papers and attended many national and international conferences. She lectures at post-graduate level on dental materials, esthetics, and orthodontics.

Dr Sandu Florin Alb is a specialist in periodontology and implantology and a full-time academic and researcher. He has co-authored three books and published 15 articles in national and international ISI journals. He has lectured at national and international conferences on ceramics, shade matching, periodontics, and esthetics. Dr Florin Alb has treated thousands of local and international patients in his private state-of-the-art dental practice. His own dental laboratory offers the full spectrum of the latest esthetic treatments, from minimally invasive techniques to pink esthetics, all types of ceramic veneers, crowns, bridges on natural teeth, and implants. He treats complex cases, combining periodontics, orthodontics, and implant placement.

Dr Ionuţ Brânzan graduated from the Faculty of Dentistry, Iuliu Haţieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania in 2005 and is qualified in dental radiodiagnosis and implantology. His practical activity focuses on dental prosthetics and implantology. He is also a 3M ESPE opinion leader and delivers lectures on dental esthetics in Romania and abroad. Dr Brânzan has published articles in prestigious Romanian, Italian, Canadian, and German journals. He is a member of numerous professional organizations.

Dr Rareş Buduru graduated from the Faculty of Dentistry, Iuliu Haţieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania and is qualified in dental radiodiagnosis and implantology. Dr Buduru has lectured at various national and international implant congresses. His practical activity is focused on implants, prosthetic reconstructions on implants, and esthetics of the anterior zone by combined tooth-implant reconstructions. He lectures in the fields of implantology and esthetic prosthetics.

Dr Smaranda Buduru is a lecturer in the Department of Dental Prosthetics of the Faculty of Dentistry, Iuliu Haţieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania. She has been a consultant in dental medicine since 2000, obtained her PhD in 2003, and has been a specialist in dental prosthetics since 2011. She is an opinion leader for 3M ESPE. Dr Buduru is the author of the following books: The clinical examination of the patient with dento-maxillary dysfunctions and Practical elements of dental occlusion. Her teaching activities are focused on dental esthetics and occlusion.

Dr Bogdan Culic is a lecturer in the Faculty of Dentistry, Iuliu Haţieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania, Department of Dental Propedeutics and Esthetics, specializing in oral surgery. Dr Culic is a lecturer on photography and dental esthetics for the Romanian Society of Esthetic Dentistry and has published numerous articles and book chapters. He is a member of various learned societies in Romania and abroad; in his private practice he focuses on dental esthetics and implantology.

Dr Lucian Chirilă is currently a lecturer in the Department of Oral and Maxillofacial Surgery of the Faculty of Dentistry, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania. Dr Chirilă is a founding member and Vice President of the Romanian Society of Esthetic Dentistry, as well as a member of the European Society of Cosmetic Dentistry and the European Association for Cranio-Maxillo-Facial Surgery. Dr Chirilă is an editorial board member of the journals Cosmetic Dentistry Romania and Actualităţi Stomatologice [Dental Updates].

Dr Bogdan Dimitriu is Professor, Head of the Department of Endodontics, Faculty of Dentistry, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania. Dr Dimitriu is a founding member and General Secretary of the Romanian Society of Esthetic Dentistry; he is also a member of the European Society of Cosmetic Dentistry and the International Academy of Dento-Facial Esthetics, and is a founding member of the Romanian Academy of Endodontics. Dr Dimitriu is a well-known lecturer in Romania, and author of various scientific papers. He is an editorial board member of Quintessence International Romania, Cosmetic Dentistry Romania, and Revista Română de Medicină Dentară [The Romanian Journal of Dentistry].

Dr Diana Dudea is a Professor in the Department of Dental Propedeutics and Esthetics, Faculty of Dentistry, Iuliu Haţieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania. Dr Dudea is the President of the Cluj branch of the Romanian Society of Esthetic Dentistry. She is a member of the European Society of Cosmetic Dentistry, the International Association for Dental Research and the Society for Color and Appearance in Dentistry, and is a lecturer for the Romanian Society of Esthetic Dentistry. Dr Dudea has published a series of books for undergraduate and postgraduate students, book chapters, and scientific papers in the field of restorative dentistry.

Dr Bogdan Galbinasu is a specialist in dentoalveolar surgery, a PhD in dental medicine, and an assistant lecturer in the Department of Prosthetic Technology and Dental Materials, Faculty of Dentistry, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania. He has vast research experience in the field of adhesion techniques which is reflected by his oral presentations, papers, and articles published in prestigious journals indexed in the Web of Science and other international databases. He has participated in six research projects and one innovation patent. His practical activity is focused on dental occlusion, dental esthetics, and implantology.

Dr Andrei Iacob graduated from the Faculty of Dentistry, Gr. T. Popa University of Medicine and Pharmacy, Iasi, Romania. He is a specialist in orthodontics and dentofacial orthopedics. Dr Iacob has participated in numerous postgraduate training programs in Romania and abroad and is a member of the following prestigious organizations: the Roth Williams International Society of Orthodontists, the Charles H. Tweed International Foundation for Orthodontic Research and Education, and the Romanian Society of Esthetic Dentistry.

Dr Alecsandru Ionescu is a graduate of the Faculty of Dentistry, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania. He is a member of the Board of Directors of the Romanian Society of Esthetic Dentistry and the Editorial Board of Cosmetic Dentistry Romania. He is also co-founder of Quintessence International Romania. Dr Ionescu is an active member of the European Society of Cosmetic Dentistry, the International Academy for Dental-Facial Esthetics, and the International Team for Implantology. He is a lecturer of minimally invasive surgery and implantology, and is currently completing his doctoral research in open healing. He practices in the fields of esthetic dentistry and oral implantology.

Dr Florin Lăzărescu is the Vice President of the European Society of Cosmetic Dentistry, a founding member and member of the Board of Directors of the Romanian Society of Esthetic Dentistry, editor-in-chief of Cosmetic Dentistry, Dental Tribune, and Today Magazine Romania. He is the author of the book Atlas de tehnică radiologică dentomaxilară [Atlas of dentomaxillary radiological technique] and has published many articles in Romanian and international journals. He is a CEREC opinion leader for Eastern and Central Europe. He practices in the fields of dental prosthetics and esthetic dentistry.

Dr Cosmin Ulman graduated from the Carol Davila University of Medicine and Pharmacy, Bucharest, Romania. He is a founding member and the Public Relations Manager on the Board of Directors of the Romanian Society of Esthetic Dentistry. Dr Ulman is a member of many national and international professional associations. His practical activity is focused on esthetic dentistry and implantology.

Dr Constantin Vârlan is a Professor, Head of the Division of Operative Dentistry in the 3 Clinical Department, Faculty of Dentistry, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania. Dr Vârlan is a founding member and the President of the Romanian Society of Esthetic Dentistry. He is a member of the European Society of Cosmetic Dentistry, the International Academy for Dental Facial Esthetics, and is an editorial board member of Quintessence International Romania, Cosmetic Dentistry Romania, and Actualităţi stomatologice [Dental Updates]. He is author and co-author of several textbooks and monographs. rd

Dr Marius Steigmann is Assistant Professor in the Department of Oral and Maxillofacial Surgery, Boston University, a visiting professor of the University of Michigan, Honorary Professor of the Carol Davila University of Medicine and Pharmacy, Bucharest, visiting professor of the University of Szeged, and visiting professor of the Implantology Department of the University of Timisoara. He is a member of DGOI, EAOI, and ICOI. Dr Steigmann is the founder and scientific president of Update Implantologie Heidelberg, as well as the founder and director of the Steigmann Institute. Dr Steigmann has a private practice in Neckargemund, Germany.

COSMIN ULMAN SMARANDA BUDURU RAREŞ BUDURU

Chapter I ESTHETIC DENTISTRY IN THE MODERN DENTAL PRACTICE

1.1 ESTHETIC DENTISTRY AS A SPECIFIC PROFILE IN DENTAL PRACTICE MANAGEMENT Esthetics is one of the never-ending medical specialties. In a world haunted by the image of eternal youth and beauty, people will always search to obtain the “perfect” image. News reports are full of stories that success and happiness follows immediately and unconditionally after a major physical transformation, and it is obvious how much everyone yearns for beauty. Esthetic dentistry is one of the most powerful instruments for renewing facial aspects, and there are studies that assert that the mouth and the smile are the most noticeable facial features. Consequently, as dental estheticians, we can certainly enter our patients’ lives and change them for the better, forever. An amusing story from a dental practice describes a female patient who had had her smile reconstructed by applying 10 maxillary dental veneers, after an almost complete body makeover. After finishing the dental esthetic treatment, she declared that everybody had noticed a change in her for the better, while the esthetic modifications of her body had remained unobserved by her close friends and relatives. Frequent discussions during esthetic dental congresses refer to the following questions: “Is there an esthetic dentistry and an unesthetic one?” and “Do I want to make an esthetic restoration today and a non-esthetic one tomorrow?” We do not want to believe that these contrasts exist, but definitely the final results differ from dental practice to dental practice and from patient to patient. The difference between a dentist who specializes in esthetic dentistry and a general dentist is that the former, before starting a treatment, will make an evaluation of the smile and of the type of patient. This will assume solid knowledge regarding facial, dental, and periodontal esthetics, as well as good communication skills, in order to understand what the patient wants and expects. In conclusion, the dentist must be not only first and foremost a professional, but also a fine psychologist.1,2 This is why we thought of systematizing the factors that differentiate between a dental practice with exceptional esthetic results and one with more modest results. These factors are related to the dentist, personnel, equipment, patients, and management.3–5 Let us say we have a dental practice, new or old, and we would like to change its profile and concentrate more on dental esthetic treatments. Where should we begin? How should this transformation take place? Once, during a congress where several esthetic cases were

presented, I heard some dentists in the room talking and complaining that they did not have patients who “would ask for such treatments”. This idea is totally wrong! Never, or extremely rarely, will a patient ask the dentist for a certain type of treatment. The algorithm we should follow is: information; knowledge; practice; proposal; persuasion; and, finally, undertaking the treatment. In other words, the dentist must have state-of-the-art information and must undertake as many continuing medical education courses as possible, and dedicate a good part of his/her free time to accumulating new esthetic dentistry knowledge. We consider that anyone can become a successful esthetician, the only question is: What should one give up for this purpose? Mainly, a great deal of free time needs to be dedicated to study.6–8 For this training to be successful in daily practice, dentists should make an informed choice regarding the types of courses that could offer them these skills. We consider that, in addition to esthetics courses in prosthetics, dental occlusion, color, dental photography, periodontology, and implantology would be necessary. The knowledge acquired during courses and congresses should be permanently added to and developed by reading reference books in the field and subscribing to various publications in order to be continually updated about new trends and technologies.9,10 The personnel of the esthetic dentistry practice must always be trained, according to their position, in the treatments that are carried out in the dental practice. The patient’s first contact is the person who answers the phone at the reception desk. This person plays a major role because s/he offers the first impression, which can be defining for the whole office. S/he should be a pleasant and extremely professional person, who will win the patient’s trust and offer enough information about treatments in a way that will persuade the patient to make an appointment. Subsequently, the meeting with the receptionist must strengthen this first good impression. Moreover, the receptionist should be able to offer relatively complex information regarding the different treatments. The details of the treatments will be offered, of course, by the dentist. The dentist’s personal assistant is one of the most important people, as s/he is closest to the dentist, knows the treatment stages in detail, and can provide the patient with valuable information. The personal assistant can also confirm the dentist’s professionalism and qualities by telling the patient about successful cases completed by the dentist. Very often patients trust information offered by a team member because that team member does not have a direct material interest in the case.11 Dentists are at the top of this ladder and, until they meet the patient, their image must be

enhanced each time the patient meets with other team members. This is why the way the auxiliary staff talk, as well as their smiles and general appearance, influences the dentist’s image. When meeting the patient, the dentist must be able to listen to the patient’s wishes, to inspire trust and confidence, and to explain all possible treatments in such a way that the patient can easily understand. S/he must present all treatment types that may meet the patient’s needs, instead of waiting for the patient to suggest his/her own ideas for treatment. The esthetic dentistry practice must be congenial, clean, nicely perfumed, and have an attractive atmosphere. There should be numerous photos showing wonderful smiles, albums with “before” and “after” cases, explanatory videos, and brochures, which will encourage the patients’ interest and their wish to obtain more information. In addition, the practice should be equipped with all that is necessary for performing the esthetic treatment correctly: an esthetic analysis sheet; a very good camera and everything that has to do with photos and case documentation; large-screen computers and smile design software; a large range of composites to form the mock-ups; rotary instruments (turbines, multiplication pieces, reduction pieces, finishing pieces, precalibrated mill sets, and specific forms for making precise preparations); augmentation optical instruments (dental microscopes or loupes); quality materials for making the provisional works, in color ranges with pigments and glazes; precision impression materials, preferably with automatic mixing for increased quality; specific materials and instruments for expanding the sulcus; equipment for optical impression; colorimeter and spectrophotometer for colored maps; materials for bonding; airborne particle-abrasion instruments; ultrasound baths; isolation systems; several adhesive cement systems; and finishing systems. The patient entering the esthetic dental practice has specific wishes and the dentist must be a good psychologist in order to make a correct selection of the patients who can be treated. Generally, the patients who want to increase their self-esteem and their self-confidence are looking for better social, personal, and professional perspectives. They have real personal complexes, or are people who have been influenced by the beautiful images reported in the media, or by acquaintances who have successfully changed their appearances – the thereby their lifestyles – in their search for eternal youth. The patients to be avoided are those who have visited several esthetic practices, have changed many of their treatments over a short period of time and for whom no treatment has been good enough, and who have a totally unrealistic vision of what they could look like. The patients who are going to be treated will become very close to the esthetician because s/he

must understand their wishes and visions about this image change. Treatment will start only after patients have understood the procedure, and accepted, by signing a consent form, the medical team that will take care of their case, as well as the timespan and the specified costs involved. After the treatment ends, the patient will have to be monitored and educated in order to maintain the correct dental hygiene and relevant lifestyle. Besides having regular checkups, patients should receive information periodically regarding new treatments as they appear (this should be done only with the patient’s consent). We suggest that patients should also be sent greeting cards for their birthdays or at Christmas or Easter, in order to show them that they are important to the practice. The dentist may become an exceptional esthetician as long as s/he is passionate about beauty in general and about esthetic dentistry in particular. We also believe that the dentist’s smile, and those of his/her team, is an additional argument for the patient to choose an esthetic solution. Knowledge regarding the materials and techniques, as well as how to achieve esthetic results, will make estheticians believe in what they are doing, and thus they will be able to easily convince their patients of the quality of their treatments. If the dentist believes in the treatments offered, so will the patient. Let’s not forget that we have the chance to change our patients’ lives, to give them back their self-esteem and to make them happy, and this is absolutely extraordinary!

1.2 INTERDISCIPLINARY COMMUNICATION AND RELATIONSHIP The remarkable progress made by dental medicine in the past decade has led to an extremely large number of available therapeutic options. To reach optimal performance in so many aspects of dental treatments, the dentist should be continuously in touch with the vast amount of information that appears (courses, presentations, specializations, etc). This is why it is ideal for complex cases to be approached and solved by a team of specialists. These specialists should work together like an orchestra, led by the esthetician dentist, who is the “conductor”. A possible scenario would be the following: the patient arrives at the esthetic dental clinic and is met by the case coordinator, who is the dentist who will write the case history, conduct the examination, establish the patient’s needs and wishes, and decide which esthetic problems should be resolved by carrying out the prosthetic procedures. At that moment, the dentist will be able to decide, after making a complex analysis, the final plan, ie, what the final result should be. Knowing the starting point (the patient’s initial situation) and the end point (the final situation with the approved esthetic result), the coordinator can propose the treatment stages. In other words, an actual treatment, assumed both by the dentist and the patient, requires that the final result is known in detail and with certainty. This final point will allow previous stages to be seen, and allow a decision about what in the initial situation has to be changed. Most of the time the dentist has a vague idea regarding the final result, and subsequently most of the stages of the case are decided as s/he is working, sometimes in an empirical manner. The patient does not know the final result and creates his/her own vision and idea, which is often completely unrealistic. Many of the tensions and problems that occur between the dentist, the patient, and the technician are caused by different visions. Without knowing the final result precisely, the dentist is in the awkward position of “selling” a final product to the patient without actually showing him/her anything. To draw an analogy, it is like a situation where someone wants to buy a car, but after arriving at the sales office, finds that there is no car inside, no possibility of a test-drive, and no photo; only the car dealer describing a potential acquisition. Would you invest a large sum of money in a car without seeing it? Highly improbable! This is why we always start a complex esthetic treatment just as one would the construction

of a house: first the outside facades are drawn (the final esthetic project), then the internal division of the house (treatment stages), then the loadbearing elements, the installations, etc (the pre-prosthetic treatment itself), and thus working back to the foundation (the patient’s initial situation). After taking all these steps, and knowing precisely the final image of the patient, we suggest a meeting of the team of specialists who will be involved in resolving the case. The team can meet physically, or a videoconference can be scheduled. At this moment, the treatment coordinator will present the case to the team (photos, models, radiographs, computed tomography scans, the final project) and they will decide on the correct staging of the case and what work each specialist has to do. This is a very important moment because all those involved will have an image of the final result and will be able to assess if the proposed intermediary stages can be finalized successfully. Each specialist will be able to explain to the coordinator exactly how each stage will be realized, how much time will be needed, and what the period required will be. The coordinator can provide exact details about the projected result, and thus all those involved can be in agreement. At this moment, the final treatment plan can be written, the approximate costs can be evaluated, an estimation of the period of time required can be made, and appointments can be scheduled for the patient. In our experience, dentists from several fields can be involved, eg, restorative therapy, orthodontics, endodontics, periodontics, surgery-implantology, in order to resolve a complex case.12,13 Now we shall examine each specialty. 1.2.1 Restorative therapy It is preferable when a prosthetic treatment is required on vital teeth that have old fillings, that these fillings should be redone, even if they seem to be correct at clinical or radiological examination. We suggest this because it is possible that when, for example, one is making the ceramic veneers on the maxillary anterior teeth, these may have proximal fillings. These fillings can produce a pulpitis after finalizing the veneers, which the patient might erroneously assume were created by the prosthetic treatment. By remaking the fillings we ensure that the teeth were treated by us, and in the case of failure, we can assume responsibility for the problem on the basis of our treatment, not that of other dentists. Another reason is that it is possible when removing the old fillings that complications of existing dental caries that were not suspected by the patient (an asymptomatic tooth) or by the

dentist could be discovered. There are situations where the patient has teeth with caries, on which prosthodontic treatment should be carried out for esthetic purposes. Even if they do not seem extensive, they should be treated before starting the esthetic treatment. We suggest this because the clinical and radiological examinations do not always provide precise information regarding the extent of the decay. Thus, the margin of the prosthetic restoration at the end of the treatment can be modified: it is known, for example, that the ceramic veneer should preferably have the margins on the enamel. Also, the color of the restorations must sometimes be changed (more often in the case of a lighter shade) in order not to influence the final result (eg, that of a thin veneer) or for the color to be matched with the bleached teeth. 1.2.2 Whitening therapy There are a series of dental whitening procedures that involve the use of thermoformed trays in which an active substance of different concentrations is applied, and which the patient can use either at home or under medical supervision. There are also whitening procedures that take place in the dental office and can be performed with the help of a polarized light lamp or a laser. These procedures have the advantage of being quicker and less painful before and after the intervention through better control of the whitening substances and of the marginal periodontium (see Chapter VIII). The whitening treatment should be scheduled in advance, as it takes some time until the color stabilizes. Also, studies show that a specific period of time between the whitening and the bonding of the veneers should be allowed in order not to compromise the quality of the adhesion.14-16 1.2.3 Occlusal therapy Occlusal therapy is one of the key factors in ensuring final success. The initial occlusal examination is vital before starting the treatment. The main objectives are occlusal stability in maximum intercuspation (MI) and centric relation (CR) and providing the functional guides (in anterior and lateral movements). Screening the active and passive interferences in the mandibular kinematics protects the dentist from future failures. The analysis of the anterior guidance is extremely important, especially for esthetic restorations in the maxillary anterior region. For example, patients

frequently have dental crowding in the mandibular anterior area. This may determine active protrusive interferences, which will produce fractures of the veneers, uneven abrasion of the incisal edges, and debonding of the classically cemented crowns. Also, inferior dental crowding requires initial orthodontic treatments or leveling of the occlusal area by selective grinding or coronoplasty, in order to make a correct upper guidance. These modifications must be explained to the patient at the beginning of the treatment and not at the stage when the ceramic reconstructions have been tried-in and signs of occlusal dysfunction appear. In this situation, we have to modify the treatment plan while carrying it out, which leads to higher costs and extra time, including the patient’s lack of compliance and compromise. Let us not forget that the passive protrusive interferences, especially in the last molars, may determine modifications in the anterior teeth (dental diastema, protrusions, extrusions, mobility), a situation which is also known as the Thielemann phenomenon.17 The lack of mandible stability in MI and CR may cause it to slide sagittally or transversally, with microshocks in the restorations and the development of complications, either in the reconstructions or in the dentomaxillary apparatus: dental (abrasions, pulp complications), periodontal (gingival recessions with the exhibition of the dental-prosthetic junction, position modifications, mobility), muscular (pains, spasms, contractures), and articular (blockages, pain, modifications in dynamics, articular noises). In global esthetic restorations, the CR position will be the only reference point.18 This is why the dentist must know mandible manipulation and CR recording techniques. In this situation, the vertical dimension of occlusion (VDO) should be considered as well. It can be modified only in CR, and by choosing an optimum VDO, the dentist can gain extra space for restorations.19 In conclusion, dental occlusion is the key factor that provides both the functional esthetic restorations and the health of the dentomaxillary apparatus. It is the esthetician’s wish that the patient should enjoy not only an improved esthetic image, but also the ability to function well with the esthetic restorations. Our patients should not only look good, but also eat well (correct mastication), speak well (correct phonation), and be able to express their satisfaction with the restorative work. 1.2.4 Orthodontic therapy Orthodontics has been (and sometimes still is) underevaluated as it is considered a treatment only for children and teenagers. But this type of treatment is an extremely important tool in esthetic dentistry. Sometimes, without preliminary orthodontic treatment, the positive results of

the esthetic treatment are improbable, or even impossible. We have tried to summarize some indications for orthodontic treatments for esthetic purposes:20,21 • Dental vertical movements: these refer to the intrusion of extruded teeth that exceed the occlusion plane and prevent the prosthetic restoration of the antagonistic arch (the correction of the occlusal sagittal curves), the intrusion of a central incisor for the symmetry of the gingival margins if a periodontal intervention is not wanted. A tooth with incomplete eruption, or the entire anterior group, can be modified in order to correct the incisal curve to be parallel with the line of the inferior lip.22 • Retrusions or protrusions of the anterior teeth whose initial position would modify the prosthetic solution or would involve a deeper tooth preparation. • In cases of diastemas that are too large, dental movements can be made in order to redistribute the interdental spaces for better proportions between width and length. • Remaking the contact points by modifying the dimensions of the interdental papillae. • Straightening the rotated teeth by opening the spaces for the dental implantations and correcting the distribution of the mastication forces in the teeth axes. • The orthodontic extraction of an untreatable tooth in order to create bone for implants.23,24 • Solving dental crowding by correcting the arch forms and the active centric line and functionally esthetic lines. • Remaking the guidances (especially in solving anterior crowding) and the occlusal stability by re-establishing the multiple contact points in MI and CR.25,26 • Slightly correcting the gingival smile orthodontically, more in connection with orthognathic and periodontal surgery.27 • Modifying the dental axes and correcting the width of the smile. All these modifications are extremely important because they aim to outline the dental, periodontal, and facial esthetics criteria, and finally help to perform a minimally invasive treatment. 1.2.5 Endodontic therapy The current trend in dentistry is called “minimally invasive”. This means a minimal preparation for veneers with a minimal sacrifice of dental structure. It is obvious that in this situation, endodontic treatment appears to be a therapy that is far away from this viewpoint. However, there are a series of situations that would indicate this therapy:28

• Extensive carious decay that compromises the pulp or is in close proximity to the pulp chamber, which would cause problems during prosthetic treatments. • Incorrect endodontic treatments. • A vital tooth that has insufficient dental tissue to ensure the retention of future crowns. • Orthodontically unrecovered dental malpositions that need a large sacrifice of dental substance.29–31 1.2.6 Implant therapy Implant therapy is an area that is continually gaining more ground in current dental practice. However, esthetics based on anterior implants requires special care. These particular aspects refer to: • Non-traumatic extractions with special instruments to allow immediate implantation. • The stability of the esthetic results, for which the area should be augmented with connective tissue graft. • The positioning of the implant, which is vital both for correct esthetics and for the prevention of subsequent vestibular recessions. • Cases where the CT shows enough bone to make a flapless implant insertion in order to avoid gingival scars in the anterior area.32–35 1.2.7 Periodontal therapy Another very important trend in dentistry nowadays is represented by the increased attention paid to the connection between periodontal and prosthetic treatments. This connection is the weak point (“Achilles’ heel”) and the place where patients most often notice that “the tooth is a fake”. Any successful esthetician should ideally have a skilled periodontist as a very good friend. More and more emphasis is being placed on pink esthetics and the junction between the tooth and the gum. The aspects in which periodontics for esthetic purposes can be of great assistance are:36–43 • Making correct gingival outlines with the symmetry of the central incisors and the gingival level of the lateral incisors below the tangent between the canines and the centrals. • Making the correct gingival zeniths. • Obtaining correct dental proportions.

• Obtaining more thickness in the fixed gingiva in order to mask the dark color of the dental root through a thin periodontium. • Remaking the outline of the vestibular cortical bone, both for implants and for the edentulous ridge in the anterior area. • Covering the gingival retractions.44 • Reconstructing the papillae.45 • Treating gingival excess. • Preparing the site for the ovate pontic in the edentulous ridge. All these surgical periodontal techniques have the role of improving the pink esthetic score, which will ensure a special final aspect and will maintain the health of the periodontal complex.45–48 Some clinical cases are now presented, which exemplify the idea of interdisciplinarity in esthetic treatments (Figs 1-1 to 1-24). Case 1: A female patient wanted six ceramic veneers from teeth 13 to 23. The teeth, at the first consultation, presented apparently correct composite proximal fillings. These had been made in another dental clinic a short time before and the patient did not want their replacement before the prosthetic treatment. When the teeth were prepared, these composite restorations became detached and it was noticed that the pulp in tooth 22 was penetrated in an asymptomatic way with necrosis (Figs 1-1 to 1-4).

Fig 1-1 The initial situation with the presence of proximal composite fillings.

Fig 1-2 The opening of the pulp chamber in 22 under the old filling.

Fig 1-3 Remaking the proximal fillings and preparing for the endodontic treatment.

Fig 1-4 The final situation.

Case 2: A female patient was not satisfied with her prosthetic treatment from teeth 12 to 22 and especially with the gum color at the level of the dental-prosthetic junction. We noticed the presence of four porcelain fused to metal (PFM) crowns and a purple color in the

maxillary vestibular area. The modified color was due to the darkened roots following a previous endodontic treatment, along with a thin periodontium. A double-purpose periodontal treatment was decided: a gingivectomy to improve the dental proportions and a connective tissue graft using the tunnel technique to thicken the gum and mask the radicular color. Secondly, four individual all-ceramic lithium disilicate pressed crowns were made (Figs 1-5 to 1-8).

Fig 1-5 The initial situation.

Fig 1-6 Gingivectomy.

Fig 1-7 Connective tissue graft (tunnel technique).

Fig 1-8 The final situation.

Case 3: A female patient wanted an esthetic restoration of the entire maxillary arch. During the examination, we noticed PFM cantilever bridges in the lateral sector and severe wear of the maxillary anterior teeth. The wear was accompanied by osseous regression and modification of the gingival level. The treatment chosen was crown lengthening with an apically positioned flap, implants, and lithium disilicate pressed crowns (Figs 1-9 to 1-12).

Fig 1-9 The initial situation showing severe wear of the anterior maxillary teeth.

Fig 1-10 Esthetic periodontal surgical treatment in order to restore the dental proportions.

Fig 1-11 The implants and the dental preparations.

Fig 1-12 The final situation.

Case 4: A patient wanted prosthetic restoration of the right mandibular arch. At the first consultation, significant extrusion at teeth 15 and 16 was noticed, which prevented any form of treatment. To restore the curve of Spee and obtain the necessary space, a segmentary orthodontic treatment, two implants, and prosthetic restoration were decided (Figs 1-13 to 1-16).

Fig 1-13 The initial situation with severe regression.

Fig 1-14 Applying the segmentary fixed device and skeletal anchorage (mini-implants).

Fig 1-15 Applying the implants.

Fig 1-16 The final situation.

Case 5: A patient wanted esthetic treatment with veneers for the six maxillary anterior teeth. Because of the crowding and of the class III angle, orthodontic treatment was decided. Periodontal treatment followed to improve the symmetry of the gingiva, which could not be

corrected with the orthodontic treatment. Finally, six feldspathic veneers were applied (Figs 1-17 to 1-20).

Fig 1-17 The initial situation.

Fig 1-18 Orthodontic treatment.

Fig 1-19 Surgical periodontal treatment.

Fig 1-20 The final situation.

Case 6: A female patient wanted a full esthetic restoration. Although the patient initially wanted the extraction of the lateral incisors, she was persuaded to undertake a fixed monomaxillary orthodontic treatment followed by a light correction at the gingiva for 11 and 22 through laser-assisted gingivectomy. Finally, pressed ceramic veneers were applied (Figs 1-21 to 1-24).

Fig 1-21 The initial situation.

Fig 1-22 Orthodontic treatment.

Fig 1-23 Laser-assisted gingivectomy and dental preparations.

Fig 1-24 The final situation.

1.3 THE RELATIONSHIP BETWEEN THE ESTHETIC DENTAL CLINIC AND THE LABORATORY AND DENTAL TECHNICIAN The dental technician is the person who succeeds in achieving implicitly the dentist’s vision and the patient’s wishes. Consequently, in this triad of dentist-patient-technician, what happens in the dental laboratory is of vital importance. For the esthetic results to meet the expectations of the patient, the dental technician’s work must be continually guided by the dentist. From the authors’ experience, and after discussions with dentists and technicians, we have come to the conclusion that this communication between the dental clinic and the dental laboratory is often hindered at several levels. The dentist often transmits only a minimum amount of information and, unfortunately, this refers mostly to the type of treatment, the execution period, and especially the laboratory fees. Then, after this frugal communication, the final result is expected to be an extraordinary one. Most often the esthetic result the dentist expects is only in his/her mind, and merely in an incipient form. In turn, the dental technician does not ask for too many instructions, sometimes because of the fear of losing a collaborator or because s/he does not know what kind of information to ask for. Each of us have a work routine and most of the time it is difficult to escape from it. I have heard on several occasions dentists talking about a certain technician and saying that s/he is very good, but that they cannot work together. On the other hand, there are laboratories where the technicians love working with a certain dentist because they have never had any problems with him/her. Leaving aside these subjective opinions, a prosthetic treatment can be finalized successfully only when the communication between the parties involved is effective. Without this objective and precise communication, a dangerous professional triangle is created, similar to the Bermuda Triangle; a triangle in which the patient is the main pawn and in which we risk losing our professional reputation. The best results are obtained when the dental laboratory is in the same place as the dental clinic because the technician can meet the dentist and the patient and participate in all the case

stages, if necessary. When this is not possible, communication must be extremely precise. Nowadays, due to the progress in long-distance communication, the possibilities of making ourselves seen, heard, and understood have increased greatly, and we must take advantage of them.49,50 As a first step, when a professional collaboration with a dental laboratory is initiated, it is most important to have an initial talk with the technician to see if a common language exists; in other words, to make sure that all ideas and knowledge coincide, or whether common ground can be achieved. Common work protocols for solving an esthetic case, as well as communication methods to be used, must also be discussed.51 At this juncture, it is also best to discuss the technical possibilities of the dental laboratory and of the dental office, the materials to be used, and the expected time frame for each stage. After these preliminary conditions have been fulfilled, the next step in defining the relationship would be setting up a clear work protocol that would be beneficial to everybody. Let us study a probable communication protocol between the dentist and the dental technician. When the patient comes for consultation, only after the case history has been looked at, the clinical examination has been made, and the radiographs and other necessary paraclinic examinations have been analyzed can the full documentation of the case begin. This documentation has the purpose of assisting the dentist to make a therapeutic decision in the patient’s absence, communicating with the dental laboratory efficiently, and ascertaining that the case is legally covered. This documentation must include: • A standard photo set (see Chapter III), which would give information about the patient’s facial, dental-labial, and gingival characteristics. • A short video, in which the patient speaks about his/her wishes regarding teeth esthetics. The video has a double purpose: on the one hand, it represents a document of the patient’s initial discourse, and on the other, it is a source of esthetic analysis. A video will show the patient’s esthetic problems better than a still photograph. • Impressions for the study models; these must be very precise and made of quality materials in order to obtain accurate study models. • Occlusal recordings, such as the recording of the upper jaw position against the skull base with the transfer facebow, occlusal recordings in CR and MI according to the case, and/or eccentric wax recordings for articulator programming. In the case of special facilities in the dental office, there could also be computerized recordings of the condyle movements by

axiography (condilography). All these recordings serve the purpose of ensuring the mounting of the models in a semi-adaptable articulator, which will be further programmed according to the patient’s condylar values. • If a VDO resizing is required, the facebow and the CR recordings are important in making this operation a success. • Sometimes, because of a discrepancy between the facebow record, the external auditory canal position, and the bipupillary line, it is necessary to transmit the reference plane from the anterior area. This can be done by using a clinometer or other devices that are attached to the facebow, or, in their absence, on the occlusion impression from the anterior area. Some reference lines can be traced, or small wooden/plastic sticks can be applied parallel to the reference lines. Sometimes, after analyzing and discussing with the patient, the dentist may be able to create a quick preview with composites (direct mock-up). This direct mock-up can demonstrate to the patient on the spot what could be achieved; it can also be a starting point for treatment and a phonetic and functional occlusal test. In addition, it can be a special marketing tool that can win the patient’s trust there and then. Pictures, videos, and study models of the direct mock-up can be added at that point to the initial documentation. After creating this documentation, the information can be sent to the laboratory physically (through impressions and the other recordings) and virtually, online (photos, videos).52 In the laboratory, after assembling the models, the first discussion between the dentist and the technician can take place. This discussion can be direct, by phone or online, but it will be based on objective data: the patient’s documentation. At this juncture, based on all the information gathered, the planning of the esthetic project can be discussed. This is done either on the basis of a Digital Smile Design, or on the basis of the laboratory record. Whatever the method chosen, the treatment plan is decided by the dentist, with the help of the technician’s suggestions, based on the patient’s wishes. The commonly agreed modifications are then written down in the patient’s laboratory record.53–55 After finalizing the treatment plan, the technician will carry out the esthetic project by waxing up the study models. This stage will be performed in a totally different way because the technician will now be able to constantly consult the patient’s photos and the record indications. The dentist will be able to test this wax-up in the patient’s mouth (indirect mock-up) (see

Chapter IV), and new photos and videos can be made to decide potential changes with the patient. These will be noted in the record, and the final dimensions of the teeth will be measured with calipers. Based on this new information, the technician can make the necessary adjustments and can create the provisional mock-up. In the office, based on the indirect mock-up, the dentist will be able to make the minimally invasive preparation, and finalize the dental preparations. Another important step in the communication with the laboratory is the impression, which can be either classical or scanned. The impression must be made perfectly and both parties involved must agree that it should be repeated until it is correct, for everybody’s sake. Also, the technician must know the characteristics of the impression material, so as not to exceed the molding time and keep the impression in improper conditions. The impression material type must be specified in the record. Regarding communication, another problem is the color of the restoration. This is often a sensitive subject and the dentist may want to leave it in the technician’s hands. We consider that all parties, including the patient, must be involved. In the technician’s absence, the color may be decided by the dentist and, with the help of quality photos, be transmitted to the laboratory with a color key next to the tooth. Also, the dentist can determine the color instrumentally (spectrophotometers and colorimeters). With regards to all-ceramic crowns, it is necessary to assess both the teeth and the dental abutments’ color. We suggest that, besides the color of the teeth, information about the macro and the micro texture, coloration, cracks, spots, and translucencies should be transmitted, and certain optical illusions should be made in the final restoration. We recommend taking some black-and-white photographs as well. Based on these data, the final restoration should not create major surprises. In the dentist– technician communication, a final point of discussion must be when to finalize the case. It is absolutely necessary for the dentist to know the ceramic type and its properties, and the technical stages of making the restorations. Thus, s/he will be able to understand how much time the technician needs. Under these circumstances, they will agree on the amount of time that will be dedicated to the laboratory work. When finalizing the restoration for the try-in, it would be ideal for the technician to participate either physically or online in order to decide the final modifications together with

the dentist. By observing this protocol (which is supported by the best theoretical knowledge), there is a very high probability of obtaining an esthetic result that meets everybody’s expectations. Communicating information that has been decided by all parties will ensure that the dentist and the dental technician function effectively as a team.56-58 In order to ensure professional success, the dentist and the technician cannot work on opposite sides, but need to take responsibility as a team.

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27. Ong M, Wang H-L. Periodontic and orthodontic treatment in adults. Am J Orthod Dentofac Orthop 2002;122(4):420–428. 28. Brindis MA, Block MS. Orthodontic tooth extrusion to enhance soft tissue implant esthetics. J Oral Maxillofac Surg 2009;67(11):49–59. 29. Kokich VG, Kokich VO. Interrelationship of orthodontics with periodontics and restorative dentistry. In: Nanda R. (ed). Biomechanics and Esthetic Strategies in Clinical Orthodontics. St Louis: Elsevier, 2005:348–372. 30. Kim SY, Tramontina VA, Papalexiou A, Luczyszyn SM. Orthodontic extrusion and implant site development using an interocclusal appliance for a severe mucogingival deformity: A clinical report. J Prosthet Dent 2011;105:72–77. 31. Plotino G, Buono L, Grande NM, Pameijer CH, Somma F. Non-vital tooth bleaching: A review of the literature and clinical procedures. J Endod 34(4):394–407. 32. Cohen S, Burns RC. Pathways of the pulp, ed. 3. St. Louis: Mosby, 1983:697. 33. Howell RA. Bleaching discolored root-filled teeth. Br Dent J 1980;148:159–162. 34. Van der Burgt TP, Plasschaert AJM. Bleaching of tooth this coloration caused by endodontic sealers. J Endodont 1986;12:231–234. 35. Zuhr O, Hürzeler M. Plastic-Esthetic Periodontal and Implant Surgery: A Microsurgical Approach. Quintessence, 2012. 36. Sclar AG. Soft Tissue and Esthetic Considerations in Implant Therapy. Quintessence, 2003. 37. Khoury F, Antoun A, Missika P. Bone Augmentation in Oral Implantology. Quintessence, 2007. 38. Priest GF. The esthetic challenge of adjacent implants. J Oral Maxillofac Surg 2007;65(7):2–12. 39. Magne P, Magne M, Jovanovic SA. An esthetic solution for single-implant restorations – type III porcelain veneer bonded to a screw-retained custom abutment: A clinical report. J Prosthet Dent 2008;99(1):2–7. 40. Zucchelli G. Chirurgia Estetica Mucogengivale, vol. 1/2. Quintessence, 2011. 41. Zucchelli G, De Santics M. The coronally advanced flap for the treatment of multiple recession defects: A modified surgical approach for the upper anterior teeth. J Int Acad Periodontol 2007;9(3):96–103. 42. Zucchelli G, De Santics M. Long-term outcome following treatment of multiple Miller Class I and II recession defects in esthetic areas of the mouth. J Periodontol 2005;76(12):2286–2292. 43. McGuire MK, Nunn M. Evaluation of human recession defects treated with coronally advanced flaps and either enamel matrix derivative or connective tissue. Part 1: Comparison of clinical parameters. J Periodontol 2003;74(8):1110–1125. 44. Bouchard P, Malet J, Borghetti A. Decision-making in aesthetics: Root coverage revisited. Periodontol 2000 2001;27(1):97–120. 45. Cortellini P, Pini-Prato G, Tonetti M. The modified papilla preservation technique with bioresorbable barrier membranes in the treatment of intrabony defects. Case reports. Int J Periodontics Restorative Dent 1996;16(6):546–559. 46. Cortellini P, Prato GP, Tonetti MS. The simplified papilla preservation flap. A novel surgical approach for the management of soft tissues in regenerative procedures. Int J Periodontics Restorative Dent 1999;19(6):589– 599. 47. Cohen ES. Atlas of Cosmetic and Reconstructive Periodontal Surgery, ed. 3. Hamilton: BC Decker, 2006. 48. Sharma AA, Park JH, Esthetic considerations in interdental papilla: Remediation and regeneration. J Esthet Restor Dent 2010;22(1):18–28.

49. Dibart S, Karima M. Practical Periodontal Plastic Surgery. Blackwell Munksgaard, 2007. 50. Borghetti A, Monnet-Corti V. Chirurgie Plastique Parodontale. Editions Cdp, 2011. 51. Vigouroux F. Guide Pratique de la Chirurgie Parodontale. Elsevier Masson, 2011. 52. Rose LF, Mealey B, Genco R, Cohen DW. Periodontics: Medicine, Surgery and Implants. Mosby, 2004. 53. Fradeani M. Prosthetic Treatment – A Systematic Approach to Esthetic, Biologic, and Functional Integration, vol. 2. Quintessence, 2008. 54. Coachman C, Calamita M. Digital Smile Design: A tool for treatment planning and communication in esthetic dentistry. QDT 2012:103–111. 55. Devigus A. All-ceramic restorations in the esthetic zone-the problem of choice. Schweiz Monatsschr Zahnmed 2011;121(6):549–559. 56. Bauer R. Using dental photography for predictable results from your dental lab. Todays FDA 2010;22(2):48– 49, 51. 57. Zary N, Johnson G, Fors U. Web-based virtual patients in dentistry: Factors influencing the use of cases in the Web-SP system. Eur J Dent Educ 2009;13(1):2–9. 58. Wierinck ER, Puttemans V, Swinnen SP, van Steenberghe D. Expert performance on a virtual reality simulation system. J Dent Educ 2007;71(6):759–766.

DIANA DUDEA CONSTANTIN VÂRLAN

Chapter II GENERAL PRINCIPLES IN DENTAL AND DENTOFACIAL ESTHETICS

2.1 EXAMINATION IN ESTHETIC DENTISTRY 2.1.1 Frontal view The facial examination is a procedure with relevance in a variety of medical fields – for example, a change in skin color or alterations of the facial expression may accompany symptoms of general diseases – as well as in plastic and reconstructive surgery. In dentistry, facial examination consists of the static and dynamic analysis of the soft tissues, facial bones, and dental arches, as well as of the relations established between these structures. Clinical facial examination is completed with frontal view and profile photos. In order to assess the bones and their relations with the soft tissues, conventional radiology and computed tomography are recommended. Moreover, the clinical examination is followed by the registration of the reference positions (centric relation, centric occlusion) that enable models to be transferred into articulators.

Fig 2-1 Anthropometric landmarks used in facial analysis – frontal view. A. On the midline: 1. Trichion – hairline. 2. Ophrion – tangent to the eyebrows. 3. Glabella – the most anterior point of the frontal bone. 4. Nasion – the upper extremity of the nose, coincident with the nasofrontal suture. 5. Pronasion – the most prominent point of the nasal pyramid. 6. Subnasion – base of the nasal pyramid (coincident with the anterior nasal spine). 7. Upper labial – the mucocutaneous point of the upper lip. 8. Stomion – commissural plane. 9. Lower labial – the mucocutaneous point of the lower lip. 10. Pogonion – the most anterior point of the chin. 11. Gnathion – the lowest point of the inferior border of the mandible, on the midline. B. Paramedian points: 12. Orbitale – the inferior point of the inferior margin of the orbit. 13. Alare – the most lateral point of the ala of the nose. 14. Cheilion – the oral commissures. 15. Zygion – the most external point of the face. 16. Gonion – the most lateral and inferior point of the face (coincident with the mandibular angle). 17. Entoconchion – the internal angle of the eye. 18. Ectoconchion – the external angle of the eye.

Fig 2-2 Lines used for facial analysis: A. The eyebrows line. B. Interpupillary line. C. Bizygomatic line. D. Subnasal line. E. Commissural line. F. Submental line.

The clinical examination uses, as reference, the distances and angles measured between external anthropometric points. Nevertheless, the interpretation of these data should take into account the correlation with the bones’ configuration and the individual variations, which depend on age, gender, and ethnicity.1–3 The face is a topographic region extending between the trichion, gnathion, and the two zygion points (Fig 2-1). The soft tissues, configuration and dynamics, as well as the bones’ architecture, are responsible for the facial appearance.4 Facial examination includes the frontal view and the profile analysis; a frontal view examination is required to establish the shape of the face, as well as the facial symmetry and proportions. In addition, the color and texture of the skin and the facial grooves are assessed, since they have a major influence on facial esthetics (Fig 2-2). The physiologic rest position, with the facial muscles in a state of relaxation, is an important

reference position for the clinical examination of the face. The patient’s head is in an upright position with the eyes looking straight ahead. The vertical dimension of the lower third, the vertical dimension of the rest position (VDR), and the corresponding freeway space between the dental arches can be measured. Depending on the situation, the anterior maxillary or mandibular teeth are visible or, on the contrary, no teeth are exposed. In orthodontics, the natural head position is used for cephalometric examination.5 2.1.1.1 Facial shape The facial shape comprises one of four types: oval or round, rectangular, triangular, or pearshaped. Both the oval- and round-shaped face have rounded angles and curved contours; however, in the former the face is longer, and in the latter, the width is broader. The oval contour is often correlated with pleasant feminine features (Fig 2-3). The rectangular-shaped face is characterized by sharp angles, squared lower third, and straight, parallel sides (Fig 2-4). The triangular-shaped face is narrow in the lower third, often corresponding to an underdeveloped mandible and pointed chin; therefore, horizontally, and sometimes vertically, the upper segments of the face are dominant (Fig 2-5). The pear-shaped face has a lower third broader than the forehead and is often correlated with a mandibular prognathism (Fig 2-6).

Fig 2-3 Oval face. Amedeo Modigliani “Alice” detail.

Fig 2-4 Rectangular face. Picasso “Pedro Manach” detail.

Fig 2-5 Triangular face. Henri Matisse “Spanish woman with a tambourine” detail.

Fig 2-6 Pear-shaped face. Hans Holbein the Younger “Henry VIII of England” detail.

The ratio between the facial height and width defines the total facial index (TFI) (height/width × 100). This index allows for the classification of the facial type into one of three groups: TFI > 104: leptoprosopic type – large values; 104 > TFI > 97: mesoprosopic –

average values; TFI > 97: euriprosopic – small values of facial height.6–11 2.1.1.2 Facial symmetry The facial symmetry represents one of the most important criteria of the facial assessment; deviations from symmetry are often the main motivation for plastic surgery and esthetic dental treatments. Clinical examination allows for the preliminary assessment of the horizontal and vertical symmetry of the facial segments; however, in order to establish the degree of asymmetry, frontal view digital images are necessary. The vertical (midline) and horizontal (interpupillary, commissural, sometimes bizygomatic, bigoniac, and submental) reference lines are drawn, and the correspondence of anatomic landmarks in relation to these lines is analyzed. Among the horizontal lines, the most important is the interpupillary line, which is the reference for the horizontal plane in the frontal view (Figs 2-1 and 2-2). These coordinates allow the assessment of the symmetry of the facial components (orbits, nasal pyramid, lips, gonion, chin). They are also used as references for the intraoral examination, in order to compare their orientation with the vertical interincisal line, upper incisal line, smile line, and gingival line.6–11 2.1.1.3 The proportions of the facial thirds In the case of normally developed facial bones and harmonious soft tissues, the heights of the three vertical segments of the face are approximately equal. In the lower segment, the stomion is positioned at the intersection of the vertical upper third (including the filtrum and the upper lip), with the lower two thirds represented by the lower lip and the chin. 2.1.1.4 The smile The smile induces changes of the physiognomy corresponding to the whole face; however, the components of the lower thirds are mostly involved: the upper lip is raised and becomes straighter, the distance between the upper lip and the nose decreases, the free margin of the lower lip becomes more concave, and the distance between the commissures increases. The smile index is the ratio of the vertical distance between the upper and lower lip and the intercommissural distance during the smile.10–12 The smile width influences the exposure of dental arches and, by so doing, forms a frame –

the esthetic zone – that should especially be taken into consideration during restorative treatments. The relations established between the facial structures and the dental arches when smiling are described in section 2.3. 2.1.2 The analysis of the profile For the clinical assessment of the profile, the patient’s head is positioned with the Frankfort plane parallel to the floor. However, according to Fradeani, this reference plane determines a slight flexure of the head; another plane – the esthetic plane – which forms an 8-degree angle with the Frankfort plane, is recommended as a reference for the horizontal plane.1 The profile analysis consists of the assessment of the relations established between the components located in the three segments of the face: the upper segment (glabella); the middle segment (points on the nasal pyramid: nasion, pronasion, subnasion); and the lower segment (points on the upper lip, lower lip, and menton – pogonion) (Fig 2-7). The profile type may be classified according to the value of the angle of the facial convexity (glabella–subnasion–pogonion) into class I (165 to 175 degrees), class II (< 165 degrees), and class III (> 175 degrees).13,14 The total facial convexity angle (including the nasal pyramid) is also calculated (glabella–pronasion–pogonion). The nasofrontal angle (glabella–nasion–pronasion) gives information on the upper and middle face; its values are reported differently in the literature (mean value: 130 degrees;15 136.38 ± 6.7 in men, 139.1 ± 6.35 in women).12 The nasolabial angle (columella–subnasion– labiale superior) presents larger variations (mean value: 60 to 90 degrees;16 102.2 ± 8 in men, 102.4 ± 8 in women;17 105 ± 13 degrees in men, 107.6 ± 8.5 in women).18 The labiomental angle (labiale inferior–labiomental fold–pogonion) was reported by McNamara et al: 133 to 134 ± 10 degrees;17 Lines et al: 120 to 130 degrees;19 Fernández-Riveiro et al: 130.7 ± 9 degrees in men, 131.4 ± 11 in women)18 (Fig 2-8).

Fig 2-7 Anthropometric points for profile analysis. A. On the midline: 1. Trichion – hairline. 2. Ophrion – tangent to the eyebrows. 3. Glabella – the most anterior point of the frontal bone. 4. Nasion – the upper extremity of the nose, coincident with the nasofrontal suture. 5. Pronasion – the most prominent point of the nasal pyramid. 6. Subnasion – base of the nasal pyramid (coincident with the anterior nasal spine). 7. Upper labial – the mucocutaneous point of the upper lip. 8. Stomion – commissural plane. 9. Lower labial – the mucocutaneous point of the lower lip. 10. Pogonion – the most anterior point of the chin. 11. Gnathion – the lowest point of the inferior border of the mandible, on the midline. B. Paramedian points: 12. Orbitale – the inferior point of the lower margin of the orbit. 13. Alare – the most lateral point of the ala of the nose. 14. Cheilion – the oral commissures. 15. Zygion – the most external point of the face. 16. Gonion – the most lateral and inferior point of the face (coincident with the mandibular angle). 17. Entoconchion – the internal angle of the eye. 18. Ectoconchion – the external angle of the eye.

Fig 2-8 Planes and angles traced for profile analysis: A. Nasofrontal angle. B. Nasolabial angle. C. Ricketts plane.

Fig 2-9 Profile field. A. Frankfort plane. B. Nasofrontal plane (Dreyfuss). C. Orbitofrontal plane (Simon).

The relative position of the most prominent points of the upper lip (Ls), lower lip (Li), and menton (Pg) is assessed. In order to establish the profile typology, the profile field is traced.

The straight profile, considered harmonious, involves the Ls point placed in the anterior third of the profile field, Li in the middle third, and Pg in the posterior third.20 A more anterior position of the Li in relation to the Ls is also considered as normal (Fig 2-9).

2.2 DENTOFACIAL RELATIONS

Fig 2-10 Exposure of the anterior teeth corresponding to the rest position – at a young age.

Fig 2-11 Exposure of the anterior teeth corresponding to the rest position – at an advanced age.

Fig 2-12 Exposure of the anterior teeth in the clinical rest position [after 24].

2.2.1 Dentofacial relations in rest position At the same time as the assessment of facial structures corresponding to the rest position is established, the degree of the anterior teeth exposure may also be established. Teeth are visible in varying degrees, depending on their size and position; other factors that influence their exposure are the conformation of the dental arches and alveolar processes in the anterior area, the volume of the lips, and the tonicity of the facial muscles. In young people, 3 to 4 mm of the maxillary anterior teeth are visible; at an advanced age, as a consequence of the abrasion and alteration of the position of the lips due to decreasing muscle tonicity, the maxillary anterior teeth are less visible and the mandibular teeth become more visible (Figs 2-10 and 2-11). The correlation of the exposure of anterior teeth in rest position with age, gender, and ethnic type was described by Vig and Brundo (Fig 2-12).24 Shorter upper lips (10 to 15 mm) enable exposures of the upper incisors of almost 4 mm, while a longer lip (31 to 35 mm) allows an average visibility of only 0.25 mm.24,25 Often, the aim is to increase the visibility of the maxillary anterior teeth with veneers or full ceramic crowns. However, not only should the esthetic outcome be envisioned, but the functional and phonetic aspects should also be taken into consideration. Repositioning of the

incisal margin of the maxillary incisors influences the pronunciation of certain sounds, the most affected being the sibilants: S and Z, and the labiodentals: V and F.1,25–27 The dynamic contacts during protrusive movements should also be carefully verified in order to prevent excessive strain on these teeth due to their lengthening. 2.2.2 Dentofacial relations in the smile As a specific form of human non-verbal communication, the smile involves the exposure of the dental arches in varying degrees, both vertically and horizontally. It is important, as a consequence, to analyze the relationship between the upper lip, lower lip, and commissures with the dental arches when the patient smiles. Frontal view photos are required, but the dynamic relations may be better observed in professional movies – the patient is encouraged to speak, to smile, and to laugh in a natural manner.

Fig 2-13 a Intermediate to low smile line.

Fig 2-13 b High smile line.

2.2.2.1 The smile line The smile line, formed by the free margin of the upper lip when smiling, should be parallel with the interpupillary line and the incisal line. The position of the smile line in relation to the maxillary anterior teeth influences the dental exposure: low smile line (revealing half of the teeth height); intermediate smile line (teeth and upper interdental papillae are fully visible); or high smile line (the smile line is 2 to 3 mm above the gingival margin of the upper incisors) (Fig 2-13). With a gingival smile, more than 3 mm of the interdental papillae and the attached gingiva are visible; when a correction of this situation is planned it is necessary to identify the causes, such as: short or hypermobile upper lip; excessive vertical development of the maxilla; or insufficient eruption of the maxillary anterior teeth. The gingival smile is more frequently encountered in women due to women having a shorter upper lip.24,28–30 The diagnosis involves clinical examination and imaging methods. Depending on the causes and the severity of the anomalies, treatment will include orthodontic, surgical, or prosthetic methods, or their combination. 2.2.2.2 Oral commissures The position of the commissures at smile influences the number of the visible posterior teeth. The decision regarding posterior teeth restorations (materials and techniques) should take into account the “esthetic zone”, or the teeth exposed when the patient smiles or laughs. It should also be noted that the exposure of the gingival tissues is equally important; moreover, it has been stated that in the premolar area, the gingiva is more visible than in the anterior zone.31 The two symmetrical areas between the oral commissures and the buccal surface of the posterior teeth (first maxillary premolars) form “the buccal corridors”, or “the lateral dark spaces” (Fig 2-14). Defined by Frush and Fisher,32 the buccal corridor may appear larger or smaller, depending on the shape of the dental arches. Larger arches, which determine the full exposure of teeth, are associated with a narrow buccal corridor. On the contrary, a narrow dentition makes a larger dark space visible, ie, a larger buccal corridor. The smaller the buccal corridor, the more ample the smile. The size of the buccal corridor is expressed as a percentage and calculated as the difference between the width of the visible maxillary dentition and the intercommissural distance, divided by the intercommissural distance.33

Fig 2-14 Buccal corridor – the space between the oral commissures and the buccal surface of the posterior teeth.

Fig 2-15 The parallelism of the free margin of the lower lip with the incisor line.

The smile is classified according to the size of the buccal corridor: • “Very narrow” smile – buccal corridor over 28%. • “Narrow” smile – buccal corridor of 22%. • “Medium” smile – buccal corridor of 15%. • “Wide” smile – buccal corridor of 10%. • “Very wide” smile – buccal corridor of 2%.33 The studies regarding the esthetic perception of dental arches indicate a preference for a smaller or absent buccal corridor.33–35

However, the stability of the results regarding orthodontic treatments applied for the expansion of the arch and minimization of the buccal corridor is questionable.36–38 2.2.2.3 Smile line The free margin of the lower lip (Fig 2-15), concave during the smile, is an extremely important reference, since, ideally, it should be parallel with the incisal line. The term “smile line”,39 or “smile curvature”,40 sometimes refers to the free margin of the lower lip, which is a valuable landmark when the restoration of the maxillary anterior teeth is the objective. The lower lip may cover the incisal margin of the upper incisors during a moderate smile, or the incisal margin of the upper incisors may slightly contact the free margin of the lower lip. In a full smile, the upper incisor line is visible against the dark background of the oral cavity – the negative central space that emphasizes its contour.

2.3 ESTHETICS OF THE DENTAL ARCHES In the clinical examination, either during a full smile or by using retractors, the following characteristics of the dental arches are analyzed: incisal line and incisal embrasures, configuration of the upper gingival line, gingival embrasures, progression of the dental dimensions, position of the interincisal lines, the alignment of teeth, and the shape and symmetry of the arches. The clinical examination is completed with complementary investigations, important among which are diagnostic models and imaging techniques. The characteristics of the dental arches influence not only the esthetic aspect, but also several functions of the oral cavity. The diagnosis and treatment plan are complex and involve numerous aspects, based on the data gained through thorough examinations. Dental examination that takes into account only esthetic considerations, and treatment plans that address only esthetic needs, may have severe consequences on the subsequent evolution of the oral system. Information provided by standard photographs and models may be used not only to complete the clinical data, but also to plan treatment. Thus, digital images of the dental arches may be processed by specific software to simulate changes in shape, position, size, and color of the teeth. Further, by using wax-up techniques, the transformations are reproduced on the models and transferred as mock-ups into the oral cavity. 2.3.1 Dental arch shape The shape of the dental arches in the anterior zone is important not only because of the wide exposure of this area when smiling, but also because it influences the position of the upper lip. The oval shape of the frontal arch is considered ideal; in maxillary deformities it has different aspects: • “V”-shaped frontal arch – lengthened, narrow arch, often with rotation and protrusion of the maxillary central incisors. • Flattened frontal arch – labial surfaces of incisors and canines parallel with the frontal plane. • Retruded maxillary central incisors, partially covered by the lateral incisors

• “M”-shaped dental arch (Figs 2-16a to 2-16d). 2.3.2 Symmetry of the dental arches The symmetrical position of the labial surfaces of the maxillary teeth in relation to the midline should be analyzed, since it affects the harmony of the dental composition. Shillingburg41 defined three types of symmetry generated by teeth shape and position: • Horizontal symmetry, characterized by uniform contours of the labial surfaces of the anterior teeth. The ensemble seems artificial and the restorations that follow this pattern look unnatural. • Radiating symmetry, which involves differences in shape among the anterior teeth. However, symmetric contours of corresponding teeth, on both sides of the midline, confers a natural outcome to the restorations. • Lack of symmetry in the frontal group in relation to the midline. Depending on the severity and location of these “deviations” from the perfect alignment of the dentition, perception may vary: the absence of a perfect symmetry of shape, size, and position of lateral incisors (and even canines) may contribute to the natural appearance and bring individuality to a dental arrangement (Figs 2-17a to 2-17c).

Fig 2-16 Dental arch shapes in the frontal area. a. Oval shape. b. Flattened frontal arch. c. “M” shape. d. “V” shape.

In contrast, for the central incisor – a dominant tooth in the arch composition – the rules of symmetry should be strict; the restoration of central incisors should avoid differences in the shape or position of the mesio-incisal angles, incisal margins, proximal contours, and cervical lines. It is acknowledged that the reconstruction of a single central incisor is one of the most challenging tasks due to the difficulties in getting a perfect match in color, shape, and position

with the contralateral tooth. Natural dentition usually presents deviations from absolute symmetry; these irregularities create a variability in the dental arch composition that is perceived as pleasant, in most cases. However, when the objective is to design restorations that deviate from the perfect dental alignment, preliminary stages, which preview the final outcome, are required: computerimaging methods, wax-ups, mock-ups, and temporary restorations.

Fig 2-17 Symmetry of the arch in the frontal area. a. Horizontal symmetry. b. Radiant symmetry. c. Deviations from symmetry.

Fig 2-18 Lack of concordance between the maxillary and mandibular interincisal lines.

2.3.3 The maxillary interincisal line The maxillary interincisal line is assessed for its inclination and correspondence with the facial midline. Ideally, the interincisal line corresponds with the midsagittal facial line. There is a belief that a deviation of 1 to 2 mm is perceived as non-esthetic;42–44 in contrast, an inclination, even if small, from the vertical axis cannot be overlooked.45,46 Regarding the correspondence between the maxillary and mandibular interincisal lines, they rarely overlap, with the deviation having little esthetic consequence (Fig 2-18). 2.3.4 The maxillary incisal line The maxillary incisal line (Fig 2-19) represents an important esthetic reference, resulting from the connection of the free margins of the central incisors, canines, and premolars (the tips of

the cusps). Lateral incisors are in a higher position, by 0.5 to 2 mm. During a smile, the incisal line becomes visible against the dark background of the oral cavity, therefore any asymmetry is easily noticed. The orientation of the incisal line is, ideally, parallel to the interpupillary line and perpendicular on the midsagittal plane. Another important reference is the parallelism between the incisal line and the free margin of the lower lip. The incisal line may present a curved, convex contour, characteristic of youth, or a horizontal outline, most often as a result of abrasion. A concave incisal line gives an unpleasant look, while asymmetries and lack of continuity may also represent factors with a negative impact on the dental composition. The triangular spaces formed between the interdental contact areas and the incisal margins – the incisal embrasures – depend on the shape of the incisal angles. Rounded incisal angles form larger embrasures that interrupt the continuity of the incisal line, while rectangularshaped incisors reduce the spaces, and the corresponding incisal line is continuous. 2.3.5 Progression of dental dimension The progression of the dental dimension from the midline may be followed for the portion of the labial surface of each tooth that is visible from the frontal view. This surface, called the apparent labial surface, reflects the incidental light anteriorly and becomes smaller with the distance from the midline due to the rotation of teeth in the arch curvature. If the maxillary central incisors are large, the lateral incisor has a smaller apparent surface, while the canine is even less visible. Therefore, in order to produce a pleasant appearance, the ratio of the mesiodistal dimensions of the surfaces of adjacent teeth should have a constant value along the arch (Fig 2-20). The value of the ratio was correlated by Levin47 with the “golden number” – thus the lateral incisor has 61.8% of the size of the central incisor, and the canine 61.8% of the lateral incisor.47,48 Other values have also been reported for the repetitive ratio between the apparent widths of the adjacent teeth (57%, 71%, 77%, and 80%).49,50

Fig 2-19 Maxillary incisal line.

Fig 2-20 Mesiodistal progression of the teeth dimensions. The repetitive proportion is noticed.

Fig 2-21 The inclination of the dental axes.

Lately, the possibility of correlating a repetitive ratio with a certain numerical value has become controversial, as neither studies nor clinical practice have consistently confirmed such data.51,52 It seems that it is not the value but the nature of the repetition that is important, namely a constant progression of dental sizes from mesial to distal (recurrent esthetic proportion).50,53 The longer the teeth, the smaller the ratio value (mean 62%), while short teeth are associated with higher values of the ratio (mean 80%).46 Correlating the mesiodistal dimension of apparent labial surfaces with the distance between the canines, Snow considers that, ideally, central incisors take up 50%, the lateral incisors 30%, and canines 20% of this space.54 2.3.6 The arrangement of dental units (teeth) – the inclination of the dental axes The longitudinal axis of the anterior teeth, which connects the gingival zenith with the middle of the incisal margin, is inclined mesially. For canines and posterior teeth, the same axis ends at the cusp tips. Ideally, these axes are parallel to each other, and have an axis that connects the external eye corner with the oral commissure, a useful landmark in prosthetic restorations of the arch (Fig 2-21).

In the distal side of the dental arch, teeth seem smaller not only in width but also in height. This is due to the “perception of depth” generated by the distance: the closer an object, the larger it is perceived to be.

2.4 DENTAL ESTHETICS

Fig 2-22 Long clinical crowns, associated with thin periodontal biotype.

Fig 2-23 Shst clinical crowns, associated with thick, fibrous periodontal biotype.

Each tooth has features that define its individuality; therefore, besides the general assessment of the dental arch arrangement, dental examination should provide information on the tooth shape, size, surface characteristics, and optical properties. 2.4.1 The dental shape In addition to the optical properties of color and translucency, the dental shape has a major impact on the final esthetic outcome. The incisors, trapezoidal in shape, have variations: the maxillary central incisors are generally more symmetrical and the angles are straighter; by contrast, the lateral incisors appear narrower, with rounded angles, especially the distal angle, and the incisal margin is

oblique, sometimes even curved. By their shape and position in the arch, the maxillary central incisors dominate the composition of the dental arches. Due to their wide exposure during speech and when smiling, their restoration and the preservation of a natural appearance is one of the most difficult challenges for the dental practitioner. Central mandibular incisors have an elongated symmetrical shape; the lateral incisor is wider. The canines show a strong morphology, mainly in youth. This is due to the presence of the cusp that points the incisal margin, giving it a “V” shape, and the prominent cervical convexity. Regarding a single tooth restoration, or that of a limited number of teeth, the adjacent and/or contralateral teeth can be used as a reference. From this point of view, the restoration of a single central incisor is very difficult, since the symmetry, the shape, and the color parameters should be precisely followed. When restoring a larger number of teeth, other references may be used, such as the periodontal biotype, the facial shape and general conformation, and even the patient’s age, gender, and personality. The elongated shape of the incisors is associated with the thin periodontal type, while the fibrous, thick periodontal complex is associated with short, rectangular clinical crowns (Figs 2-22 and 2-23).55 The shape of the face was used as a reference mainly for artificial teeth selection during full denture fabrication. Thus, according to Williams, the facial shape would be the inversed shape of the central incisor; an oval face is associated with elongated central incisors, with convex proximal margins and rounded angles; a rectangular face is associated with rectangular, symmetrical incisors; while a trapezoid face is associated with triangular teeth.56 Frush and Fisher, introducing the dentogenic concept for full dentures, and Lombardi, with the sex, age, and personality (SAP) index, have tried to correlate general traits with dental shape.32,53 Thus, among the anterior teeth, a central incisor best indicates the patient’s age, through its shape and features: the elongated shape and translucency are characteristic of young teeth, while the reduction of crown height and loss, by abrasion, of the incisal translucency occur with increasing age. Taking into account the variation of the central incisor length according to age, Misch suggests that a more constant reference for anterior teeth restoration is the position of the canine in relation to the upper lip.25

The maxillary lateral incisor presents morphological variations associated with gender: women’s incisors have more rounded angles and shapes, marked convexities, and a textured surface, while men’s incisors have right angles and a rectangular contour. The ideal position of the incisal edge is 1 to 1.5 mm higher than the central incisor.57 Personality traits have been associated with canine morphology: a strong, dominant personality is correlated with pronounced, angulated canine morphology, while a calm temperament is associated with smooth angles and ample convexities. Besides the anatomical contour of the labial surfaces, a very important role in the perception of the esthetic aspect is played by the apparent surface, namely the surface portion that projects the light forward and is visible from an anterior view. The apparent vestibular surface depends on the anatomical details of the facial surface and the position of the tooth in the arch (Fig 2-24). Thus, the more convex the labial surface of a tooth, the smaller it will appear; the flatter its surface, the larger its apparent surface, with the tooth being perceived as “bigger” (Figs 2-25 and 2-26). In canines, the mesial position of the labial ridge that starts from the cusp tip generates a smaller apparent surface.

Fig 2-24 Apparent vestibular surface.

Fig 2-25 Apparent vestibular surfaces of the lateral incisors and small canines.

Fig 2-26 Apparent vestibular surfaces of the lateral incisors and large canines.

Taking into account the tooth position, the apparent labial surface of the central incisor – almost parallel to the frontal plane – is maximal; as the teeth follow the arch curve, their apparent surface is reduced, and the mesiodistal dimensions of the apparent surfaces progressively decrease. The appearance of the dental surface is greatly influenced by the prominent structures – lobes, convex areas, crests (or, on the contrary, depressions), fossae, grooves, and striations. These are more obvious in the case of recently erupted teeth and subside or disappear with age. The vertically oriented landmarks form the “macrogeography” – lobes, and grooves between lobes, which correspond to the dental incisal mamelons that are visible posteruptively. Fine, horizontal striations, located mainly in the cervical area, are the “microgeography”. The details that form the surface texture are responsible for the diffuse reflection of light and for generating “bright” or “dark” areas that contribute to the natural

appearance of the teeth. 2.4.2 Tooth size Tooth size is conditioned genetically and may be related to distances between bone or tegumentary reference points. It is considered that the height and width of the maxillary central incisors represent 1/16 of the height and width of the face, the distance between canines is close to the interpupillary distance, while the ratio between the width of the maxillary anterior teeth and face width is equal to 1/3.3.9,27,58 Gerber associates the profile of the nasal pyramid with that of the maxillary central incisor (embryogenetic theory).59 There are studies documenting differences in the dental size between men and women.60 In the case of the anterior teeth, the width/height ratio is more important than the dental dimensions. In the central incisor this is 75% to 80%. It is increased in young people, and decreases with dental wear. A ratio smaller than 60% generates the aspect of an excessively elongated tooth, while if it is over 80%, the perception is of too wide a tooth.61

2.5 OPTICAL PROPERTIES OF DENTAL STRUCTURES Optical properties constitute a group of features that depend on the interaction of light with the hard dental structures. Incidental light – formed by radiation in the visible spectrum (380 to 760 nm) – generates various physical phenomena, which are reflected, transmitted, dispersed, or absorbed by the enamel and dentin, both at the surface and in the deep layers of the teeth. Moreover, through the stimulation of retinal receptors, reflected light from the dental surface will generate the perception of the complex chromaticity of the tooth, ie, the “chromatic map”. Its analysis involves a knowledge of the parameters that provide the overall optical appearance: hue, value, and saturation; translucency; surface gloss and texture; opalescence; and fluorescence. 2.5.1 General considerations Color coordinates, as proposed by Munsell, are hue, saturation, and value (Fig 2-27). Hue is often expressed by the generic name “color”, being generated by the wave lengths of the radiations reflected by the object: red, green, blue, yellow, etc. Dental structures are in the range of yellow to orange shades. Saturation represents the concentration of the chromatic pigment that differentiates an intense color from a pale one. The shade and saturation are analyzed in the retina by the stimulation of the cone receptor cells; there being three types of such photoreceptors, with maximal sensitivity for the detection of the three colors red, blue, and green. Value (or lightness) is an optical characteristic that depends on the amount of light reflected by an object being analyzed by the retinal rod cells. This “achromatic” property differentiates the “light” from the “dark”; generally, the greater the saturation, the more the value is reduced.11,62 The Commission Internationale de l`Eclairage (CIE) L*a*b system (Fig 2-28) is used especially in the field of research into the optical parameters of dental tissues and materials, as it allows the expression of each color numerically along three coordinates (L* – lightness axis: black = 0, white = 100; a* and b* – color coordinates in the red to green axis, and yellow to blue axis, respectively). This system allows the calculation of chroma (C*) and shade

(H*).63–65

Fig 2-27 Color parameters expressed by Munsell. Each page represents the divisions of a shade. On the vertical – luminosity axis; on the horizontal – the color saturation. (http://munsellcolor.webnode.pt/munsell-color-tree/)

Fig 2-28 The CIE L*a*b* system.

Ideally, all the restorative materials belonging to a certain color group (eg, A3 composite resins) should present the same optical parameters, regardless of the producer.65 Besides these color parameters, the optical definition of dental structures should also take into account their translucency/opacity, opalescence, and fluorescence. Transparency and translucency refer to the quality of a material to allow, respectively, the total or partial passage of light. A material that blocks the light passage is opaque. Taking the properties of transparency/translucency versus opacity into account is essential in the optical characterization of dental structures and restorative materials. Correct selection of translucency is even more important than the selection of color when composite materials are used in stratification techniques. Fluorescence defines the response of a material to ultraviolet radiations, which are

absorbed and re-emitted as radiations within the visible spectrum. This property explains the “shining white” appearance of the teeth, and obtaining a fluorescence that mimics the natural tooth is a requirement for restorative dental materials. Opalescence explains the difference in the color of a material under reflected light (such as the opal that lends its name to the term), which is perceived as blue, versus transmitted light, which is perceived as yellow/orange. Opalescence may be assessed in young teeth, at the incisal margin constituted exclusively of enamel. Another dimension that influences the optical appearance of the dental surface is the gloss, which explains the bright and shiny appearance, characteristic of the enamel surface. 2.5.2 Factors that influence the optical properties of teeth The complexity of the optical aspect of teeth is related to their particularities of shape and structure. Recently erupted young teeth have a convex surface and are well contoured, with lobes, grooves, and fossae that produce a diffuse reflection of incidental light, which accounts for their “textured” appearance (Fig 2-29). Both the convexity of the surface and the texture diminish with the attrition caused by aging (Fig 2-30). The enamel, the dentin, and the pulp – which form the tooth crown – are different from the point of view of their structure, composition, and optical properties. The pulp has less influence on the overall optical appearance; in contrast, dentin and enamel, through their properties and thickness in each tooth area, are responsible for the optical dental characteristics.

Fig 2-29 Optical properties of young dentition.

Fig 2-30 Optical properties of adult teeth.

It is considered that, due to its dominant volume, saturation, and opacity, dentin generates the global color of the tooth. This is more easily assessed in the cervical area, where the enamel is thin and dentin is seen through the transparency. The dentin, in shades of yellow, orange, and brown, has different degrees of saturation, which increases with age and may be reduced by “whitening” procedures that induce, in fact, a “desaturation”. The chromaticity of the enamel is less important; it varies in shade (white/gray or white/bluish). The optical behavior of the enamel is dominated by translucency; the thicker the enamel (as in young teeth), the lighter the general appearance. A thinner enamel layer, as in elderly persons, reveals the dentin, which accounts for the reduced lightness. Crystalographic studies indicate the possibility of correlating the dimensions of the hydroxyapatite crystals in the enamel with its lightness.66 Natural tooth colors occupy a limited area in the total color space (from light yellow to orange and light brown) (Fig 2-31).67 Understanding the optical properties of dental structures is essential for both direct and indirect restorative techniques, when composite resins and ceramic materials are used. Both the dentist’s and the technician’s objectives are the replacement of dental tissues with materials having optical properties similar to the enamel and dentin. In order to effectively mimic the dental structures, the restorative materials must have a refraction index that is as close as possible to the dental structures.68 With the layering technique, it is therefore important not only to choose materials with optical properties similar to natural structures, but also to build them in order to gain effects of chromatic “depth” that characterize natural dentition. The dentin and enamel are distributed differently in the tooth configuration, therefore the

gradient in the optical properties – color and translucency – vary along the dental crown. For this reason, the color selection should involve the analysis of each tooth area; further, these segments are assembled in order to obtain the color map for each tooth.

Fig 2-31 The space of dental colors included in the color space – area of great luminosity and reduced saturation – situated in the yellow/orange spectral domain. (http://vident.com/products/shade-management/colortheory/understanding-color-overview)

2.5.3 The analysis of the optical properties of the tooth The analysis of the optical properties of the tooth represents one of the essential stages of successful restorative dentistry. The optical dental properties are assessed by visual methods or through a technology based approach. For optimal results, a combination of these techniques is recommended, and the final result of the analysis is a “color map,” including all the features of each dental area. These “color maps” will be interpreted and transposed into different grades of opacity/translucency, saturations, and lightness of ceramic or composite materials, with the final outcome depending not only on the precision in the tooth color selection but also on the methods used for the communication with the dental laboratory, as well as the techniques used for composites or ceramic stratification. 2.5.3.1 Visual color analysis Visual color analysis includes methods aimed at comparing tooth areas with samples of shade guides. As a reference, either the tooth to be restored – if the respective color will be preserved – or the adjacent or opposite teeth may be taken. The smaller the number of teeth to be restored and the more visible their position, the more difficult it will be to match the colors

and harmonize the restoration with the dental arch composition. There are two different types of shade guides: classical and value-based. Among the classical shade guides, Vita Classical, designed in 1956 (Vita Zahnfabrik) is still the most known and widely used, despite all the limitations, generated mainly by the insufficient coverage of the dental colors, space, and irregular arrangement of the samples in this space. In other words, there is the possibility that in many circumstances the teeth analyzed would not find a correspondent among the samples and, furthermore, the difference in shade from the closest sample will be over the limit of clinical acceptance (in ΔE* units – see NOTE).

Fig 2-32 Vita Classical shade guide. a. The classical arrangement of the tabs. b. Arrangement in decreasing order of value.

NOTE: ΔE*ab represents the difference in color between two points in the color space. It is calculated by the formula ΔE*ab = (ΔL*2 Δa*2 Δb*2)½ where L*1 and L*2 are the lightness values, a*1 and a*2 the color coordinates on the yellow– green axis, and b*1 and b*2 the color coordinates on the yellow–blue axis, corresponding to the two points 1 and 2. (The minimum difference perceived by the human eye is considered to be 1,65,74 and the clinically accepted difference is 2.7 (in

vitro studies)65,74 or 3.7 (in vivo studies).65,75 These values are used in experimental and clinical studies of color analysis for teeth and restorative materials, whitening techniques, color stability, color matching, etc.

The Vita Classical shade guide is composed of 16 samples grouped into four classes of hues: A – orange shades; B – yellow; C – greenish-gray; D – pink-gray. Each group has three to four samples with progressive saturation: A1 to A4; B1 to B4; C1 to C4; and D2 to D4. It is also recommended to arrange the samples according to the value.

Fig 2-33 Vitapan 3D Master shade guide.

Fig 2-34 Vitapan Linearguide 3D Master.

In the protocol of color selection, color matching can be initiated by using the samples arranged in order of value; subsequently, the result is verified with the classical arrangement of the shade guide (Figs 2-32a and 2-32b). Images of the analyzed tooth with the selected tab are recommended; these images – transformed to black and white images – improve the perception of the value (Figs 2-32a and 2-32b).

There are also other shade guides arranged in the same mode as Vita Classical – the Ivoclar Chromascope, or the shade guides for composites used in direct restorations, etc. Value-based shade guides The Vitapan 3D Master shade guide is formed of 29 shade samples arranged into five groups of decreasing value. Each group includes shade tabs with increasing saturation in the vertical axis; the tabs are further divided by hue: the middle row has medium shades, the left row has yellowish tones, and the right row has orange shades. Value, saturation, and hue are selected in this precise order (Fig 2-33).69–72 The Vitapan Linearguide is formed of the same samples as the 3D Master, arranged in a linear manner, which reduces the number of stages of the color analysis to two: first the value is matched, then the saturation and the hue (Fig 2-34). The Vitapan Bleach guide is indicated for monitoring the results of whitening procedures. It has a wider range, especially in the light shades.

Fig 2-35 Image taken under three different light sources: a. Natural light. b. Illumination from the dental lamp. c. Ceiling light source. (Image courtesy of Dr Bogdan Culic.)

Factors that influence the visual selection of shades Although it is the method routinely used in practice for color selection and communication, the visual assessment of color is considered as subjective, influenced both by external factors and the examiner’s abilities.

Among the external factors are the texture and contour of the tooth, the illumination in the operative field, intrinsic limitations of shade guides, and the color frame that surrounds the dental arches. Moreover, the examiner differs regarding his/her color vision and experience in shade matching. The intensity and quality of light has a major effect on the color-matching process. The optimal intensity of light for dental color assessment is considered to be around 1,000 lux.

Fig 2-36 Light source with corrected spectrum, according to the natural daylight.

Among the illuminants defined by the CIE, illuminant A (tungsten filament bulb, 2,856 K), illuminants D: D50 (5,003 K), D55 (5,500 K), D65 (6,504 K), D75 (7,500 K) (simulate natural light in various conditions), and sources F (fluorescent illuminants) have direct applicability in the field of dentistry and dental research.75–77 It is important that the light source in the dental office is close, even identical, to that of the dental laboratory. Nevertheless, in practice, the illumination in the dental office is a mixture of natural daylight and the light produced by the dental lamp, as well as the ambient light sources (Figs 2-35a to 2-35c). It is recommended to use color-corrected light sources for the operative field in order to improve the lighting conditions (Fig 2-36). Due to metamerism, a restoration may be noticeable in a certain light source, even if there was a perfect color match with the adjacent teeth under different lighting conditions. However, the closer the color parameters of the restorative material to those of the natural dentition, the less evident the optical differences will be, regardless of the incidental light.76 The shade guides can induce inconsistencies in shade matching due to their failure to totally and uniformly cover the whole range of dental shades and also due to the differences that exist between their thickness, shape, texture, and material, as well as the tooth to be matched.

The results of color assessment also depend on the retinal photoreceptors produced by the cone and rod cells; the former are responsible for the analysis of color coordinates, while the latter differentiate the amount of reflected light, ie, lightness. There are three types of cones involved in color perception, which allow the perception of red, green, and blue, respectively. All the other tonalities are perceived as mixtures of these three colors. Color vision deficiencies or dyschromatopsia are anomalies of perception of one or more primary colors (frequency 8% in men, 0.5% to 2% in women). Their diagnosis is based on color vision tests (Ishihara test, Farnsworth-Munsell test); in dentistry, other standard tests that assess the individual competence in color selection are used.78–80 The accuracy of color perception decreases after the age of 40 due to structural changes in the lens; professional training and experience are factors that can improve the efficiency, but their role is controversial.81,82 In order to improve the precision of color matching in dentistry, the following rules should be considered: • When to choose the color depends on the procedure; it is preferable to do so before beginning the tooth preparations in order to have the initial image of the tooth and/or avoid dehydration; however, when the treatment involves ceramic veneers or crowns, the color analysis of the prepared tooth is also important. Communication of these data to the dental laboratory is essential for the quality of the final result (Figs 2-37a to 2-37c). In the case of full ceramic restoration, the perceived shade is a combination of the substrate, the restoration, and the material used for cementation. • The dental office should be illuminated with standardized light sources; lamps limited to the operative field are also recommended. Even if this is the case, it is useful to verify the results of the color selection under various lights in order to avoid the consequences of metamerism. • Value-based shade guides are more reliable; classical guides may be rearranged by value in order to improve the results of the value-matching. It has been stated that value mismatching is more evident than the lack of precision in saturation or hue selection.80

Fig 2-37 Image communicated to the dental laboratory. a. Discolored lateral incisors color. b. Image of preparations. c. In-Ceram Alumina crowns.

• Shade tabs should be held parallel, in the same plane as the tooth. The global color should be matched with the middle of the labial surface; however, each dental area should be analyzed separately in order to obtain the final color map. • When composites are used for stratification, the dentin shade is selected in the cervical

area; the incisal zone is the reference for the enamel shades. • The distance of assessment varies within the optimal focal distance. It is usually between 25 and 35 cm, increasing with age.

Fig 2-38 a. Spectrophotometric assessment of dental color. b. Vita Easyshade spectrophotometer.

Fig 2-39 Image taken with the Shade Pilot spectrophotometer.

Fig 2-40 Shade Vision (X-Rite) colorimeter.

• Intense colors will be removed (lipstick, make-up); it is stated that even the gingival shade, the background of the oral cavity, or the opposite teeth will influence the final result. • The assessment should consist of short periods of comparison of the tooth area with the shade tab (5 seconds). Between the intervals, it is recommended to look at a neutral gray surface.63,64 2.5.3.2 Instrumental color analysis In our technological era, the assessment of optical dental parameters benefits from the development of systems aimed to overcome the disadvantages caused by subjective visual evaluation. The principle of these devices is similar to that of other instruments used in industry for color analysis. Another advantage of using special equipment to analyze optical properties is the possibility of quantifying the color parameters by numerical values, in order to record and save the data, as well as to communicate it to the dental laboratory. The development of color devices is considered to be important progress both for research in the dental color field and for dental practice.83 The devices used in dental color analysis are the spectrophotometers, colorimeters, and imaging systems.77 Spectrophotometers are high-precision devices that analyze the spectrum of reflected light at regular wavelength intervals. As they are provided with their own light source, they are less influenced by the external light. One of the spectrophotometers widely used in practice is Vita Easyshade, an intraoral contact device that analyzes global dental color and the color on the three areas – cervical, middle, and incisal. It also has the function of verifying the optical parameters of the shade guide samples and the ceramic restorations. Cordless and more

compact than the original design, the latest versions, Vita Easyshade Advanced and Compact, are easier to handle. The results of the color coordinates are transformed in the coding systems of the Vita Classical and 3D Master shade guides. 77

Table 2-1 Instrumental systems used for color analysis in dentistry.

Device

Manufacturing company

Functioning principle

Measured dental surface

ClearMatch

Clarity Dental

Software analysis of digital image

Full dental surface

CrystalEye

Olympus America Center Valley

Spectrophotometer

Full dental surface

Easyshade Advance

Vident, Brea

Spectrophotometer

Surface with 5 mm diameter

Shade X

X-Rite Grandville

Spectrophotometer

Surface with 3 mm diameter

ShadeVision

X-Rite Grandville

Colorimeter

Full dental surface

SpectroShade Micro

MTH, Niederhasli

Spectrophotometer

Full dental surface

Shade Pilot

Degudent, Dentsply

Spectrophotometer

Full dental surface

Their limitations originate from the flat surface of the detector, which must achieve an extended contact with the convex dental surface, and from the difficulties caused by the free positioning on the tooth surface. Due to the edge-loss effect, not all the light entering the tooth is received into the device and analyzed (Fig 2-38). Colorimeters measure the tristimulus values, filtering the light in the areas corresponding to the colors red, blue, and green. They are less accurate than spectrophotometers. An advantage of these systems is the possibility of displaying the image and generating maps of hue, saturation, value, and translucency. An example is the Shade Vision™ (X-Rite) colorimeter (Fig 2-40). Digital cameras are a less complicated means used for color analysis and communication. Standardized dental images are analyzed with professional versions of software that allow the expression of the color coordinates by numerical data.

Fig 2-41 The Sopro 717 Acteon camera used for color determination.

The advantage is the possibility to assess other dental characteristics: form, texture, position. There are intraoral cameras provided with special software for color selection (Sopro 717 Acteon camera). This camera allows the visualization of half of the tooth image on the monitor; images of shade guide samples can be recorded next to it, progressively, so that the most appropriate color can be judged (Fig 2-41).72 Table 2-1 presents a selection of the instrumental systems of color analysis existing on the market.77 Among the disadvantages of the instrumental systems of color analysis are high costs, as well as the difficulties in obtaining a constant result for the same area (reproducibility), due to the difficulties in the exact repositioning. In order to obtain the most accurate results in color section, the visual and instrumental techniques are combined. The color quality of the final restoration also depends on the communication of these parameters to the laboratory (more often, as digital images of the tooth with adjacent shade-guide samples, or as detailed color maps obtained during visual and instrumental analysis), as well as the method used to process the dental material.

2.6 GINGIVAL ESTHETICS Besides the characteristics of dental shape, position, and color, the appearance of the adjacent gingival tissues must also be assessed. A harmonious composition can only be achieved in relation to healthy periodontal structures. Factors that have to be evaluated are the gingival color, the gingival line, and the exposure of the free gingiva, attached gingiva, and interdental papillae while smiling (Fig 2-42). Periodontal examination, which includes clinical data, is mandatory for a complex diagnosis. This clinical data includes bleeding on probing, probing depth, and loss of attachment measurement, as well as information obtained by radiographic imaging, microbiological tests, and immunological tests. The inflamed or recessed gingival tissue is not an ideal frame for natural dentition or a dental restoration, and the final outcome cannot generate an overall satisfying image. The healthy attached gingiva has a coral-pink color and a firm, textured appearance; this area is exposed only in the case of a high smile line (or gummy smile). The interdental papillae are positioned in the gingival embrasure, below the area of interdental contact. Their elongated aspect, slightly convex, in combination with the scalloped margin of the free gingiva that follows the cervical line, frames the clinical crown. There are two different periodontal biotypes: • “Thick” periodontal structure, characterized by dense, fibrous gingival tissues and reduced convexity of the free gingiva. This periodontal biotype is associated with wide crowns. • “Thin” periodontal structure, with a convex, scalloped free gingiva; long interdental papillae; and thin, narrow attached mucosa. The epithelium is thin and transparent. The correspondent crown shape is elongated, even triangular. In the case of subgingival margins of the restorations, there is an increased risk of an esthetically unpleasant result, especially with metal ceramic crowns. Moreover, a thin periodontal structure is more frequently associated with gingival recession.55 In anterior teeth, the mesiodistal and vertical position of the highest point of the gingival margin, or the gingival “zenith”, is important, since it influences the perception of the tooth axis inclination. Magne and Besler84 indicate a distal position of the gingival zenith for all the maxillary anterior teeth, while Rufenacht30,86 considers that the lateral incisor has the gingival zenith centered. According to Chu,85 the zenith of the upper central and lateral incisors is

slightly distal in relation to the central axis of the tooth (1 mm distance for the central incisor and 0.5 mm for the lateral incisor), while for the canines the gingival zenith is centered mesiodistally (Fig 2-43).

Fig 2-42 View of healthy gingival tissues.

Fig 2-43 View of the gingival zenith.

The connection of the gingival zenith corresponding to the maxillary canines and central incisors forms the gumline, which should be parallel with the horizontal plane. The zenith of the lateral incisor is at a distance of 1 mm from this line.85 The angle formed by the connection of the zenith of the upper incisors and the canines should be opened apically, since the zenith of the upper lateral incisor is positioned lower than the neighboring teeth by 0.5 to 1 mm. A reversed angle, as encountered in class II division 2 anomalies, associated with the overlap of the lateral incisors over the centrals, or asymmetrically gingival contour in relation to the midsagittal plane, have a negative impact on the esthetic appearance (Figs 2-44 and 2-45). The height of the interdental papillae may be

correlated with the crown height. In the case of gingival recession, the gingival embrasures become visible as dark triangular spaces; their exposure while smiling may be extremely unpleasant and the therapeutic approach should combine, in these cases, prosthetic methods with periodontal reconstructive techniques.

Fig 2-44 Normal gingival line.

Fig 2-45 Reversed gingival line.

REFERENCES 1. Fradeani M. Esthetic Analysis. A Systematic Approach to Prosthetic Treatments, vol 1. Chicago: Quintessence, 2004. 2. Anic-Miloševic S, Lapter-Varga M, Šlaj M. Analysis of the soft tissue facial profile by means of angular measurements. Eur J Orthod 2008;30(2):135–140. 3. Anic-Miloševic S, Meštrovic S, Lapter-Varga M, Dumancic J, Šlaj M. Analysis of the soft tissue profile in Croatian with normal occlusions and well-balanced faces. Euro J Orthod 2011;33(3):305–310. 4. Dudea D. Noţiuni de Examinare în Estetica Dento-facială. Cluj-Napoca: Ed. Grinta, 2010. 5. Bass NM. Measurement of the profile angle and the aesthetic analysis of the facial profile. J Orthod 2003;30(1):3–9. 6. Vâlceanu A, Anghel M, Colojoară C. Noţiuni de Estetică în Stomatologie. Timişoara: Ed. Lito UMFT, 2000. 7. Ieremia L, Bratu D, Negruţiu M. Metodologia de Examinare în Protetica Dentară. Timişoara: Ed Signata, 2000. 8. Milicescu V, Milicescu ID. Creşterea şi Dezvoltarea Generală şi Cranio-facială la Copii. Bucureşti: Ed. Viaţa Medicală Românească, 2001. 9. Rominu M, Bratu D, Uram Tuculescu S, et al. Aparatul Dento-Maxilar. Date de Morfologie Funcţională Clinică. Timişoara: Helicon, 1997. 10. Renner PR. An Introduction to Dental Anatomy and Esthetics. Chicago: Quintessence, 1985. 11. Goldstein RE. Esthetics in Dentistry, ed 2, vol 1. Hamilton: BC Decker, 1998. 12. Bratu D, Jivănescu A. Procedee de Examinare, Diagnostic şi Elaborare a Planului de Tratament în Estetica Dento-facială. Timişoara: Litografia UMF, 2005. 13. Arnett GW, Bergman RT. Facial keys to orthodontic diagnosis and treatment planning. Part I. Am J Orthod Dentofacial Orthop 1993;103:299–312. 14. Arnett GW, Bergman RT. Facial keys to orthodontic diagnosis and treatment planning. Part II. Am J Orthod Dentofacial Orthop 1993;103:395–411. 15. Epker BN. Adjunctive esthetic surgery in the orthognathic surgery patient. In: McNamara JA, Carlson DS, Ferrara A (eds). Esthetics and the Treatment of Facial Form, monograph 28, Craniofacial Growth Series. Ann Arbor: University of Michigan, 1992:187–216. 16. Burstone CJ. Lip posture and its significance in treatment planning. Am J Orthod 1967;53:262–284. 17. McNamara JA, Brust EW, Riolo ML. Soft tissue evaluation of individuals with an ideal occlusion and wellbalanced face. In: McNamara JA, Carlson DS, Ferrara A (eds). Aesthetics and the Treatment of Facial Form, monograph 28, Craniofacial Growth Series. Ann Arbor: University of Michigan, 1992:115–146. 18. Fernández-Riveiro P, Smyth-Chamosa E, Suárez-Quintanilla D, Suárez-Cunqueiro M. Angular photogrammetric analysis of the soft tissue facial profile. Eur J Orthod 2003;25(4):393–399. 19. Lines PA, Lines RR, Lines CA. Profilemetrics and facial esthetics. Am J Orthod 1978;73:648–657. 20. Scheid RC, Weiss G. Dental Anatomy, ed 8. Philadelphia: Lipincott Williams & Wilkins, 2012. 21. Ricketts RM. Esthetics, environment, and the law of lip relation. Am J Orthod 1968;54:272–289. 22. Steiner CC. The use of cephalometrics as an aid to planning and assessing orthodontic treatment. Am J Orthod 1960;46:721–735. 23. Bass NM. The aesthetic analysis of the face. Eur J Orthod 1991;13:343–350.

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BOGDAN CULIC FLORIN LĂZĂRESCU ALECSANDRU IONESCU

Chapter III THE PHOTOGRAPHIC EXAMINATION

3.1 FUNDAMENTALS OF DIGITAL DENTAL PHOTOGRAPHY Dentistry is a branch of medicine which has always used photography. There are many fields in dentistry to which digital photography can be applied: • Case documentation and archiving. • Communication with patients. • Communication with the dental laboratory. • Forensic medicine. • Medical teaching. • Marketing the dental office and illustrating specialized publications. The requirements of dental digital photography are: • Correct exposure (illumination) in the oral cavity. • Sufficient depth of field. • Corresponding working distance. • Adequate magnification ratio. • Correct subject framing. • Reproducing the natural colors of teeth and soft tissues. • Rapidity in the taking of the photograph. In photography, whether it be artistic, medical, dental, or photography of any other nature, the fundamentals are the same. These fundamentals must be known in order to understand the functioning mechanisms of a camera, and to take good photographs. 3.1.1 Exposure Exposure determines the quantity of light which correctly impresses a photosensitive surface, whether it be a classical film or a digital sensor. Two combined devices that are present in all cameras allow the photographer to “lead” the light: a. The diaphragm (aperture), which, like the iris, serves to regulate the light flow allowed into the camera due to the diameter of its aperture. Theoretically, if the light source that

illuminates the object to be photographed is strong, a low aperture value on the diaphragm is required. When the illumination of the object is reduced, a large aperture is required. As cameras use lenses of different focal lengths, to ease the determination of the exposure parameters the term “f-number” was introduced, which represents the relation between the focal distance (f) of the lens and the aperture diameter (D), and is noted as f/D. In the case of a 200 mm lens and a 50 mm aperture, the f-number will be 200/50 = 4, and it is noted f:4. Taking into account the fact that the diaphragm has a circular aperture and the light flow that crosses it depends on the whole surface, the result is that doubling the flow is proportional to a 1.4 ratio, which is applied to the aperture diameter. Conversely, halving the light flow is the result of shrinking the aperture diameter by 1.4. In light of this mathematical formula, a range of fnumber levels are used that do not rigorously observe the 1.4 progression, but which are imposed in practice and are universally used: f/1; 1.4; 2; 2.8; 4; 5.6; 8; 11; 16; 22; 32; 45; 64, etc (Fig 3-1). On a camera, the aperture setting is usually adjusted in discrete steps, known as f-stops. b. The shutter is the component that allows the adjustment of the exposure time of the photosensitive surface to the light rays. This exposure duration, also called the shutter speed, is expressed in fractions of a second. These, as well as the aperture values, are internationally standardized. An exposure time of 1/500 s will leave only a small amount of light to impress the sensor; a slow speed of 0.5 s allows a large amount of light; but a potential movement of the photographer or the subject during this time will create a final blurred image. The exposure is ensured by two main parameters, the aperture and the exposure time (Fig 32). Theoretically, the mutuality principle allows the small apertures to be compensated by a longer exposure time, as they induce more depth of field, which is required in dentistry.1,2 3.1.2 The depth of field The depth of field can be defined as the area in front and behind the plane for which the focus was made, where all the objects are represented clearly in the photo. The clarity area is very important for the dental photo and it indicates the location of the focusing plane. It depends on several parameters:

Fig 3-1 The f-number.

1. The aperture is inversely proportional to the depth of field (Fig 3-3). This means that in order to obtain a large depth of field (a photo with clear incisors and molars), small aperture diaphragms (standard f/16 or f/22) must be used. Theoretically, to achieve the maximum depth of field, the diaphragm should be closed more, up to f/32, but in this case diffraction will appear and the image will be distorted. However, for dental photography a small aperture must be compensated for by using powerful flashes, such as ring or twin flashes.

Fig 3-2 The exposure parameters.

Fig 3-3 The relation between depth of field and the aperture.

Fig 3-4 The distribution of the depth of field is placed 1/3 in front and 2/3 behind in respect of the focusing plane. If the focus is clearly on the incisors, the lips and the canine-premolar area will show. If the focus is on the canines, both the incisors and the molars will be clearly defined.

Fig 3-5 The focusing area for obtaining the maximum depth of field.

Fig 3-6 The magnification ratio: 2:1 and 1:2, respectively.

2. The photography distance is proportional with the depth of field. When taking a photo of an object that is 10 m away, the depth of field is twice as large as it would be if the object were 5 m away. The depth of field (the clarity area in a photo) is distributed as follows: 1/3 in front of the subject, and 2/3 behind (Fig 3-4). If a photo of a complete dental arch is required, in order to use the entire depth of field, and for the incisors and molars to be in sharp focus, the focus must be on the canines – focus, reframe, and then take the shot (Fig 3-5).3,4 3.1.3 The magnification ratio The magnification ratio refers to the ratio between the real dimension of an object and the dimension of its image on the 35 mm film, or full-frame sensor (Fig 3-6). For the sake of uniformity, it has been established that the magnification ratio should be calculated by using 35 mm film (24 × 36 mm) as a reference.5 A magnification ratio of 1:2 signifies that the object has half of its real dimension on the film. For a 2:1 ratio, the object will have double the dimension (Fig 3-7). These magnification ratios are usually marked on the macro lenses that are used in dental photography. If the conventional lenses are used with non-full-frame digital camera bodies, inconsistencies can occur when expressing the magnification ratio. The non-full-frame digital cameras use sensors of different dimensions. Generally, these have smaller dimensions than the classical 35 mm film (eg, Nikon D7000 – sensor 15.6 × 23.6 mm). The ratio between the diagonal of the classical film and the diagonal of the digital camera sensor is the calculation

formula for the crop factor for a DSLR camera. For the majority of DSLRs, the crop factor is between 1.3 and 2 (eg, for Nikon D7000, it is 1.5) (Fig 3-8).

Fig 3-7 Magnification ratio 2:1. Left: real object dimension. Right: object image on film.

Fig 3-8 Crop factor illustration. Image taken with the same lens. In the red frame is the image on the 35 mm film, the blue frame shows the image on the sensor with the 1.5 crop factor.

Fig 3-9 a,b Standardizing before and after images. Magnification ratio 1:1.2. Choosing a constant magnification ratio allows the same dental structures to be in the picture, the viewer’s eye concentrating on the treatment, in this case, ceramic veneers on teeth 13 to 23.

This means that the magnification ratio obtained by a Nikon D7000 digital camera and a classical lens will be, in fact, 1.5:1 (these characteristics are found in 90% of the systems currently on the market). The focal length of a classical lens of 100 mm, assembled to a Canon body, will be 160 mm (corresponding to the 1.6 crop factor). The magnification ratio is very important in standardizing and reproducing photos (Figs 39a and 3-9b) and is used in dentistry as follows: • 1:10 portraits. • 1:2 whole dental arch. • 1:1.2 canine to canine. • 1:1 photo of the four incisors. • 1.5:1 photo of the central incisors – details Figs 3-10a to 3-10f. 3.1.4 The focal length The focal length corresponds to the distance expressed in mm between the optical construction point of the lens and the optical distance when focused at infinity. The focal length of the lens is associated with the magnification, as well as with the viewing angle of the photographed

objects (Fig 3-11). Lenses can be grouped into two main classes: telephoto lenses (400, 300, 200, 100 mm) are lenses with a high focal length, which bring the subject very near but have a low view angle, while lenses with a low focal length (10, 17, 22 mm) have a higher view angle. If the photo is taken from too short a distance away, distortions and irregular illumination of the object may occur. A useful rule is for the working distance to be 1.5 times the diameter of the ring flash, or the distance between the two flashes (for twin flash).4 For dentistry, macro lenses with a focal length between 60 and 105 mm are recommended, with 100 mm being considered as standard. These lenses with high focal lengths ensure a comfortable shooting distance, even for high magnification ratios (1:1).

Fig 3-10 a–f Photos taken with different magnification ratios.

Fig 3-11 Photos taken with the lens at different focal lengths. The field of view shrinks as the focal length increases.

The ISO sensitivity, a number defined by the International Organization for Standardization, indicates the film or the sensor sensitivity with regard to the light source; the higher the number, the higher the sensor’s sensitivity. For example, an ISO 400 will need a smaller amount of light to impress the sensor, in comparison with an ISO 100. An increase in the ISO results in some negative aspects as well, which are represented by the noise captured by the sensor. This noise is translated into images with a degree of granulation, which increases as the ISO increases and results in color distortion and disturbing effects. In dental photography,

strong light sources are used; this is why a low value ISO of 100 or lower is recommended to obtain clear, high-quality images. 3.1.5 Choosing the devices Cameras can be classified into two main classes, each having its advantages and disadvantages: • Compact cameras. • Professional cameras. 3.1.5.1 Compact cameras Compact cameras are divided into two categories: cameras for the public and semiprofessional cameras (Fig 3-12). The first category comprises cameras costing between $150 and $500, which have very good digital sensors and uncomplicated software. They only rarely allow the choice of the exposure mode and the zoom function is usually of poor quality. The “macro” working mode, when it exists, is not enough to ensure good-quality, reproducible photos (poor exposure, the presence of shadows, distortions, color problems). These cameras should only be used for extraoral photography.6 The semi-professional cameras, costing between $500 and $1,500, have very good digital sensors and more sophisticated software. The optical part, the zoom, is of a high quality, and the macro mode allows focusing close to the subject. They allow the choice of exposure modes, especially the “aperture priority”, which helps manage the depth of field. The presence of the LCD screens allows instant checking of the focus. 3.1.5.2 Professional cameras Professional cameras are the most suitable for intraoral dental photography. The DSLR (digital single lens reflex) cameras have interchangeable lenses and are best adapted to dental photography when a macro lens and a corresponding flash are used.7

Fig 3-12 a,b Compact cameras.

Fig 3-13 a-d DSLR camera bodies (images courtesy of F64).

We consider the low-end and middle-end DSLR models to be the best for intraoral dental photography (Fig 3-13a to 3-13d). They have all the features required for the purpose and are reasonably priced, compared to high-end cameras with fewer features. We therefore recommend the purchase of a middle-end camera body with the addition of good-quality lenses and flashes. The high resolution of the DSLR digital sensor, as well as that of some compact cameras

(often those with over 10 million pixels), produces large files that are difficult to use. The large number of megapixels – often marketed as an important characteristic of digital cameras – does not lead to better-quality images if the images are viewed on a monitor with a resolution of 1,920 × 1,080 pixels (2.1 million pixels). High resolution digital sensors are therefore not important in intraoral dental photography; the dentist uses the photo for case documentation, not for high-dimension prints.8 DSLRs have different working modes: • Auto mode – the camera sets the aperture, the exposure time, the ISO sensitivity, etc according to surrounding conditions. • Aperture-priority mode Av (A) – the photographer sets the diaphragm value, and the camera determines the exposure time automatically. • Shutter-speed mode Tv (S) – the photographer chooses the desired exposure time, and the camera calculates the necessary aperture. • Manual working mode (M) – the photographer sets the exposure settings. This is the recommended working mode for dental digital photography (Fig 3-14).

Fig 3-14 Selecting the working mode.

Fig 3-15 a-e Lenses used in dental photography (images courtesy of F64).

Fig 3-16 Magnification ratio (in yellow) selected on the zoom view.

Fig 3-17 Intraoral image taken with a compact camera using a flash. Note the lack of focus and depth of field, and how the teeth are irregularly lit.

3.1.6 The lens The lens is perhaps the most important element when a DSLR camera is used. It must have a long enough focal length, as the magnification ratio is proportional to the distance that separates the lens from the digital sensor. A proper “macro” lens allows for the continuous passage from infinity focus to 1:1 ratio focus by simply spinning the focus ring.9 All manufacturers offer lenses with a focal length of between 35 and 200 mm. The best lenses for dental photography are those with a focal length of between 100 and 105 mm (Fig 3-15) as they allow a magnification ratio of 1.6:6 (100 mm lens, at a crop factor of 1.6) (Fig 3-16). There are many types of lenses presently on the market that are classified according to the focal length in the fixed lens (fixed focal length, eg, 100 mm) and in the zoom lens (variable focal length, eg, 18 to 55 mm). Fixed lenses are recommended for dental photography because zoom lenses rarely allow the choice of a magnification ratio higher than 1:4. 3.1.7 The flash The flash is indispensable in intraoral dental photography. High-quality dental photos of frontal, occlusal, and lateral incidences are difficult to achieve due to a lack of light, the presence of shadows, and the need for precise focus. These problems can be solved by using a flash. Compact cameras with internal flashes are not recommended (Fig 3-17). Instead, use a compact camera with an external diffusor (Fig 3-18), as these distribute the light uniformly on the object being photographed.

Fig 3-18 Compact camera with external diffusor (Petitjean International).

Fig 3-19 a,b Ring and twin flashes.

At present, the most frequently used light sources for dental photography are circular (ring) flashes and bilateral (twin) flashes (satellite systems). These are fixed onto a ring which is attached to the lens. With integrated TTL (through the lens) function, the flash power is adapted automatically to the subject when taking the photo (Figs 3-19a and 3-19b).

Ring flashes are easy to position, which is very useful when photographing posterior teeth and difficult areas, and for function and form (in surgery). A major disadvantage of this type of flash is that it causes uniform illumination without shadows, which leads to a flat image. Ring flashes are therefore not recommended when photographing the anterior area, where esthetics is important, because the uniform illumination obstructs the details and the translucencies, and may cause annoying reflections. The use of twin flashes is recommended if a natural image is to be obtained because it results in a better reproduction of the colors, the morphological details, the surface texture, and the translucency of areas (Fig 3-20a and 3-20b). The settings of the camera offer a mid-value exposure. Initially, the flash produces a preflash before the main flash, which is reflected from the surface of the object being photographed back into the camera. If the object reflects light strongly, the power of the flash is automatically diminished so as to obtain the average value; if the object reflects light poorly, the power of the flash is automatically increased. Due to the color spectrum of the dental units, the images obtained by the automatic control of the exposure (TTL II) will usually be too dark because of exposure reduction. In this case, it is necessary to compensate the flash exposure (+2/3) in order to obtain a correct exposure (Figs 3-21a to 3-21c).

Fig 3-20 a. Photo taken with ring flash b. Photo taken with twin flash (same subject, same camera body and same lens – different flash).

Fig 3-21 Flash exposure compensation.

For intraoral dental photography, the new wireless twin flash (Nikon R1) is recommended, which is attached to the master ring fixed onto the lens (Fig 3-22). Depending on the camera body, the master controller of the twin flash can either be built-in or a supplementary command system. Up to four satellites can be attached to the master ring, but only two are used in practice. Compensatory settings of the flash for correct exposure are necessary with this new device when the flash is used in the manual mode. In this instance, the photographer has to quantify, with a few attempts, the amount of light needed for the photo. The advantages of using the flash in the manual mode are: • The exposure can be modified depending on the magnification ratio. • The exposure and the colors are more accurate. • The tone intervals are larger. • The images are clearer. 3.1.8 The image-file format in digital photography In digital photography, the most frequently used formats for image files are JPEG, TIFF, and RAW, the last being considered the real “digital negative”. Even though the JPEG format is usually used in daily dental photography with very good results, in the case of images prepared for presentations or print, this format may not satisfy the current requirements. JPEG (Joint Photographic Experts Group) • The image is compressed. • Every time the image is saved, it loses quality. • The image needs reduced storage space (1/2 up to 1/50 of the original size).

• The image can be processed, but every time it is rotated, a new compression results.

Fig 3-22 Nikon R1 wireless twin flash.

TIFF (Tagged Image File Format) • No compression occurs when the image is saved again. • The image needs reduced storage space at half of the original dimension. • The quality of the image is very good for printing. • The image can be processed. RAW • The original data are recorded in binary uncompressed format. • It represents the equivalent of an unprocessed 35 mm film. • It needs special image post-processing software. • The image can be edited or changed. • The image is of the highest quality. • The files are extremely large. The images obtained are used, processed, stored, and archived with the help of image postprocessing software (eg, Adobe Lightroom), in order for them to be used for different purposes: • Primary consultation and treatment planning. • Case history and personal archives. • Esthetic evaluation, self-evaluation, and simulation in the case of esthetic rehabilitations. • Communication with the dental laboratory. • Presentations and publications.

• Marketing.10 3.1.9 The white balance An important objective in dental photography is to obtain images with natural color rendition. The white balance is the function that can make the difference between an image with natural colors and one that may not reflect the reality – with consequences that can cause problems in communication with the dental laboratory, for example.

Fig 3-23 Setting the white balance to flash mode.

The white balance has several settings, depending on the light conditions when the photo is taken. Daylight is characterized by a color temperature of 5,500 K. A cloudy sky is 6,500 to 8,000 K, a fluorescent light is 4,000 K, and a tungsten light bulb is 2,800 K. When the photographer specifies the dominant light source when taking the photo, the white balance tries to correct the image to reproduce the colors as close to natural daylight conditions as possible. For dental photography, the main light source is represented by the flash (the temperature of the light source from the electronic flash is 5,500 K, which represents a standardized natural illuminator) and the white balance must be set to the flash mode (Fig 3-23). Automatic white balance is not recommended in dental photography, while the manual adjustment of the white balance should only be done by experienced photographers; furthermore, it does not necessarily result in more natural color reproduction.

3.2 INTRAORAL PHOTOGRAPHY

Fig 3-24 Example of standard camera settings for intraoral photography.

Fig 3-25 Framing the subject.

3.2.1 Intraoral photography settings What should the settings of a camera be for taking intraoral images? In daily dental photography, standard settings that will help obtain good-quality photos are recommended. In order to obtain artistic images or other details that the photographer specifically wants, these settings can be modified. For a high depth of field, the diaphragm should be set at a low-value aperture (f/6 to f/22). This means that a small amount of light will enter the digital sensor. Theoretically, in this case, a longer exposure time is required in order to obtain sufficient illumination of the object. If a longer exposure time is set, a potential movement of the photographer or the subject while the photo is being taken will create a final blurred image

(dental photography requires hand-held cameras that are not placed on a tripod).4 Using the ring or twin flash – which provide a very powerful light – will reduce the exposure time to 1/125 to 1/250 s in order to obtain the correct exposure. These settings can mostly be selected on cameras that have the M (manual) mode. Standard settings for intraoral photography: • Manual working mode (M). • Objective focus – on manual focus mode (MF). • Diaphragm: f/16 to 22. • Exposure time: 1/125 to 1/250 s. • Choosing the corresponding magnification ratio. • ISO (sensitivity) 100. • WB (white balance) – flash. • Flash – set on TTL function. Using these standard settings, the photographic system should be used in the following way: • Dental photography requires a hand-held camera. • The desired magnification ratio is chosen depending on the area to be photographed, according to known values. • Focus is achieved after various attempts, moving closer to or further away from the subject. • Framing the subject is achieved by looking through the view finder and positioning the horizontal grid parallel with the occlusion plane, and the vertical grid parallel with the interincisal line (Fig 3-25).

Fig 3-26 Intraoral retractors. (Image courtesy of Doctoreyes GMBH.)

Fig 3-27 Mirrors used in dental photography. (Image courtesy of Doctoreyes GMBH.)

Fig 3-28 Taking a picture of a small dimension prosthesis: a. Positioning, b. Result. The dark background and the reflection of the restoration are given by the strong illumination of the mirror surface.

Fig 3-29 Contrastors (Image courtesy of Doctoreyes GMBH.)

3.2.2 Accessories for intraoral photography The retractors Obtaining good-quality intraoral images is not possible without the use of cheek retractors. Transparent polycarbonate retractors of different sizes and shapes are most commonly used. They are comfortable for the patient and can be modified, if necessary. They are sterilized in an autoclave at 121°C or 134°C. Individual retractors, which are available in pairs, allow the guided retraction of the lips in order to expose the area to be photographed. They can easily be modified by half sectioning, allowing for better retraction when mirrors are used for taking photos of the occlusal surfaces (Fig 3-26). The mirrors Mirrors are indispensable for taking pictures of the occlusal and lateral surfaces of the teeth (Fig 3-27). They can also be used as a background for highlighting small-sized prosthetics (Figs 3-28a and 3-28b). Mirrors are available in different shapes and sizes. The minimum mirror set comprises an occlusal mirror and a lateral mirror. With their help, the following can be obtained: • Images of the maxillary and mandibular occlusal surfaces. • Images of the buccal surfaces of the lateral teeth. The external surface of the mirrors must be treated in order to reflect 85% to 99% of the light. Having an ultrareflective external surface will prevent the formation of double images coming from the reflected light in both internal and external mirror surfaces. Rhodium-coated mirrors are recommended for dental photography. Before placing the mirrors into the oral cavity, they must be warmed up (insert them into hot water, or heat them at a heat source) to

avoid fogging. The assistant can also use the air syringe to clear the fogged-up area.11,12 The contrastor The contrastor is an accessory that creates a dark background for taking images of anterior teeth (Fig 3-29). The structures of the oral cavity behind the teeth are eliminated and the transparency of the incisal edges of the teeth are emphasized (Fig 3-30). The contrastor is made of black anodized aluminum or bendable copper sheet overmolded with silicone rubber. It can also be made from black cardboard cut in corresponding shapes.13

Fig 3-30 Images with and without contrastor. The transparencies in the incisal area are emphasized.

Fig 3-31 The photographer’s position.

3.2.3 Taking intraoral images It is recommended that intraoral photos be taken in standard, reproducible conditions. Any staff member should be able to take photographs in a simple, fast manner with good results if s/he respects the camera settings and follows the practical procedures. Standardization of dental photography is essential for best results with minimum effort.

The patient should be comfortably seated in the dental chair, his/her head lower or at the same level as the camera. The dentist or the dental assistant who is taking the photos should find a comfortable, stable position, because the camera is hand-held and can sometimes be of a considerable weight. The right hand will hold the camera body, and the left hand will hold the anterior part of the lens. One eye should be positioned in such a way as to look through the viewfinder, while the other eye remains open (Fig 3-31). The next stages are selecting the right magnification ratio, focusing by approaching and moving away from the subject, and, finally, triggering. 1. The frontal view a. Overview of buccal surfaces of the teeth (molar to molar).

Fig 3-32 Frontal view a. Positioning, b. Result, ratio 1/2.

Fig 3-33 Frontal view - details a. Positioning, b. Result, ratio 1/1.2. c. Ratio 1/1, d. Ratio 1.5/1.

• Pair of extensible retractors for separating the soft tissue. • The magnification ratio is 1:2 (Fig 3-32). b. Frontal view of anterior teeth • Pair of extensible retractors. • The magnification ratio is 1:1.2 (canine to canine) or 1:1 (the incisors) (Figs 3-33 a to 333d). 2. The lateral view a. The image of the maxillary and mandibular quadrants from the same side. • Pair of retractors are used by enlarging the one that corresponds to the photographed quadrant to the maximum. • The magnification ratio is 1:1.5 (Figs 3-34a and 3-34b).

Fig 3-34 Lateral view. a. Positioning. b. Result.

Fig 3-35 Lateral view. Position of the retractor and lateral mirror. a. Positioning. b. Result.

Fig 3-36 Maxillary occlusal view. a. Positioning. b. Result.

Fig 3-37 Mandibular occlusal view. a. Positioning. b. Result.

b. The image of the buccal surfaces of the lateral teeth in occlusion. • A lateral mirror is used, which is placed into the side that is going to be photographed, its end touching the distal surface of the last molar, enlarged laterally as much as the cheek elasticity allows. A retractor is placed in the opposite side.

• The magnification ratio is 1:1.5 to 1:1 (Figs 3-35a and 3-35b). 3. The maxillary occlusal view • An image of the occlusal surfaces of the maxillary teeth is obtained. • An occlusal mirror is used in the oral cavity in contact with the gingival mucosa distal to the last maxillary molar and supported by the incisal edges of the mandibular teeth, with retractors for enlarging the soft tissue from the maxillary area. • The magnification ratio is 1:2 (Figs 3-36a and 3-36b). 4. The mandibular occlusal view • Obtaining the image of the occlusal surfaces of the mandibular teeth. • An occlusal mirror is placed into the oral cavity in contact with the gingival mucosa, distal of the last mandibular molar and supported by the incisal edges of the maxillary incisors. Patients will be invited to lift their tongue in the palate and breathe through the nose. The retractors will be used to enlarge the soft tissue from the mandibular area. • The magnification ratio is 1:2 (Figs 3-37a and 3-37b). The complete photographic status for a patient will comprise the photos below (Fig 3-38), taken in standard, reproducible conditions. These can be taken both during and at the end of the treatment.14,15

Fig 3-38 Photographic status for a patient.

Fig 3-39 Photographs of some specific zones in the oral cavity.

Besides photographing the dental arches in the standard positions described previously, a series of photos are taken to emphasize certain details in some specific zones in the oral cavity (Fig 3-39). 3.2.4 Taking portrait and profile images

The portrait photo is used mainly in esthetics, prosthodontics, surgery, and orthodontics. If these images are taken for case documentation purposes, the patient must be positioned according to a specific worked-out plan. 3.2.4.1 The background color There is no standard background color; however, it is recommended not to use too many background shades so as not to tire the eyes of the readers or those attending the presentation. Gray shades do not affect the color of the photographed objects. Colors as background shades – full colors or color gradients (the last give the photo a certain depth) – can be used. A white background can be used when dark objects need to be emphasized.2 A dark background is the most effective because it emphasizes the luminosity of the photographed objects and also gives them a three-dimensional effect. 3.2.4.2 Choosing the equipment for extraoral photography The same photo system can be used as for intraoral photography except for the ring flash, which is not useful in this case. If extraoral photos are frequently taken in the practice, it is recommended that an area be especially created for this purpose. The background in this area should be monochromatic, and neutral colors (eg, gray) are recommended.16 Lighting can be created by studio lights or strong flashes that offer sufficient illumination, to an aperture value of f/11 (Fig 3-40). Use the anthropometic reference points to correctly position the patient for frontal and lateral photographs. For portrait photography, the patient’s head must be placed so that the bipupillary plane is parallel with the horizontal plane of the image. The subject should be framed in such a way that the superior margin of the photo is level with the head’s superior extremity, and the inferior margin is in the larynx area. The indicated standard magnification ratio is 1:10 (Fig 3-41).

Fig 3-40 Photographic setup for portrait photography.

Fig 3-41 Portrait image.

Fig 3-42 Profile image.

For profile photography, the Frankfort plane will be parallel with the horizontal plane of the image. The patient looks ahead, in a relaxed manner. The following will be in the frame: superior – the hair; inferior – the larynx area; as lateral sides – the earlobes (the hair will be tied back, leaving the earlobes visible); and the profile area. Illumination will be achieved using light sources placed bilaterally, in front of and behind the patient. Where only an external source of light is used, the light should be situated in the anterior zone to avoid the creation of shadow zones made by the patient’s profile. For the documentation of esthetic rehabilitation patients, extraoral images, such as the oblique lateral view or the semi-profile photo, should be taken. The magnification ratio recommended is between 1:8 and 1:10, but to make things easier, the same magnification ratio can be used as for the frontal view or profile photos.

REFERENCES 1. Bengel W. Digital photography in the dental practice: An overview (I). Int J Comput Dent 2000;3(1):25–32;138– 143. 2. McLaren EA, Terry DA. Photography in dentistry. J Calif Dental Assoc 2001;29(10):735–742. 3. Ahmad I. Dental Photography. Chicago: Quintessence, 2004. 4. Bengel W. Mastering Digital Dental Photography. London: Quintessence, 2006. 5. Sandler J, Murray A. Clinical photographs – the gold standard. J Orthod 2002;29(2):158–167. 6. D’Incau E. Photographie dentaire: Le matériel. Inf Dentaire 2006;88(36):2243–2248. 7. Bengel W. Digital photography in the dental practice: An overview (II). Int J Comput Dent 2000;3(2):121–132. 8. Vargas MA. Photographs of the face for publication and presentations. J Prosthodont 2003;12(1):47–50. 9. D’Incau E. Photographie dentaire: Les méthods. Inf Dentaire 2006;88(41):2649–2653. 10. Goldstein CE, Goldstein RE, Garber DA. Imaging in Esthetic Dentistry. Chicago: Quintessence, 1998. 11. Vargas MA. Maxillary and mandibular occlusal photographs. J Prosthodont 2003;12(2):149–151. 12. Vargas MA. Maxillary and mandibular lateral view photographs. J Prosthodont 2003;12(3):227–229. 13. Vargas MA. Photographing a view of the maxillary anterior teeth with a black background. J Prosthodont 2002;11(3):208–210. 14. Chu SJ, Devigus Al, Mieleszko A. Fundamentals of Color. Shade Maching and Communication in Esthetic Dentistry. Chicago: Quintessence, 2004. 15. Touati B. Esthetic Dentistry and Ceramic Restoration. London: Martin Dunitz, 1999. 16. Paravina RD, Power JM. Esthetic Color Training in Dentistry. St Louis: Mosby, 2004.

SMARANDA BUDURU RAREŞ BUDURU

Chapter IV DENTIST–PATIENT COMMUNICATION DURING ESTHETIC ANALYSIS INTEGRATING PROVISIONAL ESTHETIC REHABILITATION IN THE TREATMENT PLAN

4.1 DENTIST–PATIENT COMMUNICATION DURING ESTHETIC ANALYSIS

Fig 4-1 Worn teeth.

Fig 4-2 Protruded teeth.

Fig 4-3 Teeth with gaps.

Fig 4-4 Retruded teeth.

One of the main challenges of esthetic dentistry – an elective restorative dental service – is to determine the patient’s requirements and expectations right from the beginning; namely, to make a clear-cut distinction between the patient’s actual and perceived needs.1 This course of action has to be taken before starting medical procedures and making irreversible changes to the dentoperiodontal structures. Therefore, we believe that the dentist should be a true “magician” when conducting the anamnesis of the patient so that s/he can obtain as much relevant information as possible. Psychologically, there are several types of patients: • Patients who know what they want. • Patients who do not know what they want. • Patients with reasonable expectations. • Constantly dissatisfied patients. • Ideal patients for whom any type of treatment is excellent.

Besides the informative preliminary interview, several objective methods exist whereby a case can be previewed and the final result anticipated. It is recommended that a standard set of photographs be taken before initiating the treatment (see Chapter III). These are used to discuss the case with the patient, as well as with the dental technician in the patient’s absence. At the same time, as many people are rather awkward or shy in front of the camera, it is recommended that a video recording of the patient when talking and smiling is made in order to get an accurate picture of his/her lip dynamics, tooth visibility, and various everyday expressions. Following the extensive conversation with the patient, the comprehensive esthetic and functional analysis should be written down in the patient’s medical record. The case has then been fully documented and the final outcome can be previewed. Preview techniques include: • direct mock-up • diagnostic wax-up • indirect mock-up • digital smile design. 4.1.1 Direct mock-up Definition The direct mock-up consists of applying light-curing composite resin on the teeth, without bonding agents, to change their size, form, color, and position with the purpose of previewing the proposed modifications. The technique can be successful when treating shortened worn teeth or teeth with gaps and no facial volume, but it cannot be used for making the teeth shorter, or to correct protruded teeth (Figs 4-1 to 4-4). Armamentarium • Light-curing composite materials in different colors (lighter colors are generally recommended); can also be flowable versions. • Modeling instruments. • Finishing burs, discs, rubbers, polishing paste. Technique

The procedure always begins by placing the composite resin on the incisal edge of the central incisor, which represents the key starting point of the dental restoration. The new length of the tooth should be esthetically, phonetically, and functionally (anterior guidance) acceptable to the patient.2–5 After deciding the position of the incisal edge and the length of the central incisors, the mesiodistal edge is determined to keep the optimal 75% to 85% length/width ratio.

Fig 4-5 Initial situation.

Fig 4-6 Direct mock-up: determining the position of the incisal edge.

Fig 4-7 Giving a finishing touch to the mock-up.

Fig 4-8 Direct mock-up: final form.

The facial side is restored next, paying attention to the reshaping of the facial contour and its curvature in relation to the length of the upper lip, in order to maintain proper ratios. After the central incisor build-up, the lateral incisor, canine, and premolar are restored, maintaining the best proportions between teeth and complying with all the principles of esthetics: the incisal edge curvature parallel to the curvature of the lower lip, optimal interdental contact areas, and incisal and periodontal embrasures (see Chapter II). Finally, the composite is refined to achieve the proper shape and length. This should be done very carefully so as not to damage the tooth.6 Light-colored composite resins are recommended for two reasons: patients always wish to have brighter teeth, and because it is easier to distinguish the color difference from the existing dental structure (Figs 4-5 to 4-8). Conclusions

The composite mock-up allows the patient to preview the proposed outcome in a short period of time, get a good idea of the final result, and make suggestions for further improvement.

Fig 4-9 Initial situation.

Fig 4-10 Direct mock-up.

Fig 4-11 Extended gingival mock-up.

Fig 4-12 Esthetic periodontal surgery.

Fig 4-13 Final form.

At the same time, the dentist gets an accurate representation of the envisaged result and can objectively assess its esthetic, phonetic, and functional viability. Subjectively, s/he can also arrive at a better understanding of the patient’s wishes and expectations. In circumstances where, after lengthening the incisal edges, the patient displays phonetic impediments or lower-lip interferences, but the teeth are still too short and the dental ratios incorrect, the apical side of the mock-up will be modified, resin will be applied on the gingiva, and the cervical contour will be reshaped, which would possibly require periodontal esthetic surgery (Figs 4-9 to 4-13).7 Once the patient and the dentist have agreed upon the treatment plan, it is recommended that an impression is taken and a study model is made in the laboratory. These procedures are the starting point of the laboratory wax-up. At the same time, it is recommended that the new dimensions of the tooth are measured with a dental caliper, and the written information is transferred to the laboratory.

Instead of looking in the mirror to evaluate the direct mock-up, the patient should look at the photos or video recordings to see how others see him/her. Most specialists agree that looking in the mirror leads to inaccurate self-assessment.8 The mock-up method is easy and reasonably priced, and yields immediate results. The advantages are that it allows the practitioner to immediately start a planned treatment that has been agreed upon with the patient, or to stop the process without delay and with no “collateral damage”.9,10 4.1.2 Wax-up Definition The wax-up is a replica of the patient’s dental arcades based on initial study models prior to the dental rehabilitation, with the purpose of previewing the final result. Once validated in the oral cavity by the indirect mock-up, the wax-up becomes the starting point for any further treatment decisions. Conditions Several conditions are required for a correct diagnostic wax-up, including high-quality impressions of the patient’s initial status. High-quality impression materials, such as polyvinylsiloxane (PVS), are recommended for this process. The impressions are used to make casts according to the best technical procedures and following all the manufacturer’s instructions for use. It is also recommended that extra-hard Class IV dental stone is used, and that extra care is taken to remove excess material so that the casts fit into the articulator (Figs 4-14 and 4-15).

Fig 4-14 Initial situation.

Fig 4-15 Study model.

Fig 4-16 Facebow record.

Fig 4-17 Computerized axiography recording.

Fig 4-18 Mounted casts in the semi-adjustable articulator.

Fig 4-19 Programming the incisal table (anterior guidance).

Fig 4-20 Results of computerized axiography.

Fig 4-21 Programming condylar guidance.

The casts are mounted in the semi-adjustable articulator. Based on facebow registration, the upper cast is mounted to faithfully replicate the position of the maxilla relative to the cranial base. The lower cast is mounted relative to the former in maximum intercuspation (MI) or centric relation (CR), depending on the extent of the rehabilitation and the occlusal stability. Customized programming of the articulator (condylar inclination, Bennett angle) is recommended in order to simulate jaw movements as accurately as possible. Computerized

axiography or wax recordings of anterior and lateral movements may be used in programming the articulator (Figs 4-16 to 4-21).2,11–14 Armamentarium Once the casts are mounted in the articulator, the dental technician can proceed with the diagnostic wax-up. For this purpose, he/she needs wax and modeling instruments. White modeling wax is generally recommended to produce a diagnostic wax-up model as it is supposed to be more pleasing to the patient. At first sight, a gray, green, or any other color wax model may dishearten the patient and change his/her mood, or adversely affect the patient’s trust in the treatment. There are modeling wax kits with various pigments that can be mixed to replicate the future chromatic effects created in porcelain as closely as possible. In the authors’ experience, a plain white (as white as possible) wax model has a very positive impact on the patient. In order to be more accurate, the use of a mechanical or electronic caliper to measure tooth size is recommended. A periodontal probe for sagittal and transverse measurements would also be useful. Role • Changing volume, size, ratio, and shape for every separate tooth. • Replicating tooth macro and micro texture. • Changing tooth-to-tooth ratios. • Modifying periodontal and incisal embrasures, as well as interdental contact points and areas.16 • Changing the gingival contour. • Setting the position and direction of the incisal edge. • Accentuating or softening incisal angles. • Changing or restoring occlusion curves (Spee, Wilson). • Restoring stable, balanced, and simultaneous contact points between dental arcades. • Changing the vertical dimension of occlusion (VDO). • Restoring anterior (overbite, overjet) and lateral (canine, lateral, anterolateral) guidance, depending on functional requirements.17,18 As the dental technician cannot achieve these (esthetic and functional) changes randomly, the dentist must convey a set of additional data to the laboratory in addition to the cast mounted in the articulator. The information must be recorded in the clinical notes in order to avoid any

misunderstanding between the dental clinic and laboratory, and the changes to every separate tooth must be noted down specifically. For instance, “the length for tooth 11 will be modified by adding 1 mm to the incisal edge and 0.5 mm to the gingival area; the initial overjet will be augmented from 1 to 1.5 mm and it will be reshaped to a triangular form”. Sometimes, when an extensive correction of dental position is required, the technician will have to remove parts of the wax-up model stone; in such cases, the technician must write down these changes in the clinical record so that the dentist is aware of the situation when proceeding to the indirect mock-up.2 At the same time, the clinical notes would be better accompanied by a set of high-quality photos (see Chapter III), which the technician could constantly refer to while molding the waxup in order to accurately understand the dentist’s requirements. It is recommended that these photos are accompanied by electronic clinical notes that can be placed online. Electronic records allow long-distance collaboration with the technician, preserve the quality of the photos and allow them to be enlarged or downsized, and are material evidence in dentist– technician communication. Conclusions The wax-up is the dentist’s initial plan, his/her vision for the patient’s treatment put into practice in the laboratory by the dental technician. The initial plan is carried out based on the patient’s suggestions, the esthetic and occlusal analysis, and, possibly, on the direct mock-up. Once completed in the laboratory according to the initial requirements, the wax-up will be tested in the patient’s oral cavity by an indirect mock-up. At this point, other adjustments can be made to refine the wax-up. This is the actual foundation of the final result that will first be turned into a provisional, and then intro a final restoration. The patient can thus approve of the “final” result from the very beginning and avoid unexpected surprises. Furthermore, this model (“blueprint”) will be a guide for the following preprosthetic procedures and help to ensure their success: periodontal treatment, orthodontic procedures to modify tooth positions, endodontic treatment for atypical and extensive tooth preparation, and implants.

Fig 4-22 Incisal edge built up.

Fig 4-23 Measuring the new length of the tooth.

Fig 4-24 Checking the new dental ratio.

Fig 4-25 Determining the final position of the incisal edges.

Fig 4-26 Molding the new shape.

Fig 4-27 Completing the facial side.

Fig 4-28 Molding the lateral incisors.

Fig 4-29 Final wax-up.

The initial model will allow the technician to become a true artist within the confines of esthetic and functional requirements. Thus, the functional and creative aspects are decided from the very beginning. In the final stage of porcelain restoration, the technician’s creativity will be limited to chromatic and optic effects. This means that no one from this professional “triangle” (patient–dentist–technician) will have any unpleasant surprises at the end or lose any sleep over the project (Figs 4-22 to 4-29). 4.1.3 Indirect mock-up Definition The indirect mock-up is prepared by the technician. The wax-up is inserted into the patient’s oral cavity by the dentist before any irreversible changes to the dentoperiodontal structures are made.

Role • Testing the dentist’s planned changes for the patient, envisaged during the preliminary analysis, as well as during the esthetic, occlusal, and phonetic assessments. • The patient is able to preview the final result. • The result can be modified following an agreement between dentist and patient, starting from a real-life, actual image. • The patient can be photographed or filmed in order to get a more accurate idea of what the final restoration will look like. • The patient can be evaluated by the people close to him/her, whose opinions matter. • When the patient is in agreement with the final result, s/he signs a consent form that enables the dentist to go ahead with the treatment plan (a significant point that may help the dental and technician teams to avoid legal issues). • Deciding the stages of preprosthetic treatment and initiating the interdisciplinary approach. • Providing guidelines for tooth preparations for prosthetic purposes (Gürel technique).19 • The starting point of provisional restorations. Armamentarium • Diagnostic wax-up models and/or duplicate wax-up models. • Putty silicone or thermoformed matrix. • Self- and/or light-curing composite resins. • High-speed and contra-angle handpieces. • Burs in various sizes and grits. • Discs, rubbers. • Polishing pastes. • Provisional cements. Technique Once the wax has been applied on the initial laboratory models (wax-up), the information must be transferred into the patient’s oral cavity. First, a dental impression is taken, either partial (when working only on a few teeth) or full arch. Standard trays are used when restoring several dental units or the whole dental arch. Putty impression materials, regular or transparent, may be used in a standard or transparent plastic tray. The latter has the advantage of allowing visual control inside the impression, and light transmission from the light-curing lamp.

The impression tray is inserted into the patient’s oral cavity in order to find the best position. It is then filled with self-curing or light-curing flow composite and applied against the dental arches. Once the impression material has cured, the tray is removed, and only the resin that helps preview the final result remains on the teeth. Many specialists recommend that the patient refrains from evaluating the esthetics of the reconstruction in the mirror, but rather looks at the photos taken at this point. A short video recording is also advised in order to take the natural movement of the lips into consideration.8 After polishing and adjusting have taken place, the patient is presented with the final result and invited to discuss potential changes. The transparent putty impression enables a better view of any bubbles or air pockets inside the resin, the overflow of excess material, and potential deficiencies.

Fig 4-30 Wax-up models.

Fig 4-31 Wax-up impression.

Fig 4-32 Filling the impression with resin.

Fig 4-33 Indirect mock-up.

If changes have been made to the indirect mock-up inside the patient’s mouth (when compared to the initial wax-up), an impression of the new situation is recommended. This ensures that the technician has a new model to use when altering the initial wax-up. In addition, if tooth length is to potentially change, each tooth dimension should be measured with a caliper and written down in the clinical notes to avoid any future misunderstanding (Figs 4-30 to 4-33). As wax can break while taking the impression of the wax models, certain specialists recommend that extra-hard stone replicas of the models are made in the laboratory. Next, more rigid thermoformed matrices that will hold the composite resin during indirect mock-up are built on the models. The transparent guard allows the resin on the teeth, potential bubbles, air pockets, and flaws to be seen, and enables curing. Once the resin has set, the procedure is similar to the first technique described in this section (Figs 4-34 to 4-36).20–22

Conclusions At this point, once the patient has been analyzed, the dentist can distinguish the limitations/opportunities/possibilities of the case, plan related procedures, see whether the patient’s expectations are reasonable enough, and, above all, ensure that the three perspectives (dentist–technician–patient) coincide. This moment is crucial in defining the professional relationship with the patient and, in theory, should help to avoid unpleasant surprises and results. Once the patient has consented to pursuing the agreed-upon form of treatment, written consent should be signed in which the patient accepts sole responsibility for any further modifications that s/he may request. As patients often listen to the opinions of the people who are close to them, it is recommended that they be given time to go home with the preview in order to share it with their family and friends, and get ideas and/or suggestions. In most cases, the resins form a very thin layer (especially on mispositioned teeth), which makes these teeth impossible to remove without breaking them. Therefore, the mock-up should be carefully polished. Consistent thickness is possible only in cases of retruded teeth that are to be brought back to a normal position. The dentist can remove the mock-up and proceed to provisional cementation so that the patient can go home with it.

Fig 4-34 Wax-up.

Fig 4-35 Wax-up replica.

Fig 4-36 Thermoformed matrix.

Fig 4-37 Indirect mock-up with horizontal guiding grooves (Gürel technique).

Fig 4-38 Phonetic mock-up testing.

It is recommended not to touch the tooth structure when polishing because, if the treatment is not pursued, the patient may accuse the dentist of damaging his/her natural teeth.19,23 The analysis should not be exclusively esthetic, but also functional (occlusal) and phonetic. Another recommendation is to use very light-colored resins in order to create a spectacular effect for the patient, as well as to distinguish more clearly the restoration from the existing dental structure. Another very significant aspect is that, once accepted, the indirect mock-up represents the final volume of the restoration. Now guiding grooves can be carved for a really accurate preparation of the dental structures. By carving these guiding grooves, one can be extremely careful with the dental structures and, consequently, be minimally invasive (Figs 4-37 to 4-38). The authors believe that an esthetic, functional, conservative – minimally invasive – rehabilitation is not possible without the prior visualization approved by patient, dentist, and technician. 4.1.3 Digital smile design Definition Digital smile design (DSD) consists of a virtual image of the future outcome of the treatment, starting with the preliminary photos of the patient and using specific computer software. DSD is a complex, multifunctional procedure that can improve diagnosis, communication, and treatment predictability. The authors suggest that the computerized analysis of the patient’s dental and facial features allows the dentist to identify crucial aspects that may otherwise be missed during clinical analysis.24

Armamentarium • Computer. • Software, Keynote or PowerPoint. • A set of patient photos. Role • Esthetic diagnosis: the dental team may assess the patient’s esthetic needs and analyze certain aspects overlooked by the clinical analysis. • Communication: between dentist and technician, so that the entire team is involved in the treatment. • Patient management: it is a powerful tool to motivate the patient to accept and continue the treatment; at the same time, it helps the patient to understand related procedures, and why they may be necessary.

• Educational: presentations for other patients or colleagues can be made. Technique • While a whole set of photos are taken, only three are crucial: portraits at rest and with wide smile, and maxillary arch with retractors and contrastor. • The reference lines are drawn (horizontal, parallel to the interpupillary line or the horizon, and vertical, along the medial line of the face). • The digital facebow transfer provides useful information for the dental reconstruction. • The smile is analyzed in relation to the axes in order to perceive the deviations that need to be corrected. • A smile simulation is performed by changing, for example, the position of the incisal edge, the inclination of dental axes, the gingival contours, and tooth shape or ratios. • These modifications allow the transfer of data to the technician for the wax-up model. • Finally, the patient may be shown his/her new smile resulting from the alteration of the initial photos (Figs 4-39 to 4-42).

Figs 4-39 to 4-42 DSD changes to the initial photos.

Conclusions DSD helps to create a new smile in minutes. It allows the patient to see his/her proposed new image in photographs and to consent to the continuation of the treatment. For the team involved in the treatment, it is a very efficient means of communication, allowing them to evaluate the required corrections and plan the preprosthetic procedures, as well as produce an extremely precise wax-up. DSD therefore results in a high degree of accuracy in the ultraconservative preparation of the tooth, and in the predictability of the final result.

4.2 INTEGRATING PROVISIONAL ESTHETIC REHABILITATION IN THE TREATMENT PLAN Provisional restoration is the next step in preliminary treatment. Until now, the discussion has focused on the visualization in advance of the outcome of the treatment; in other words, on the creation of a prototype of the final result through direct mock-up, wax-up, indirect mock-up, and DSD. After testing the indirect mock-up, and once the patient has consented to the initiation of the treatment, the teeth must be covered by provisional restorations. These must replicate the final diagnostic wax-up that has already been tried in the patient’s mouth, and consequently they must be as faithful a copy as possible of its most minute details. Provisional restorations have occasionally been underestimated, their role having been seen as merely to protect the prepared tooth. While this important function should not be overlooked, the authors nevertheless believe that their significance goes far beyond this role, and that they act, in fact, as a “test drive” of the final result.25–31 Role • Maintain the patient’s social life. • Shield dental structures. • Further validate the esthetic project. • Validate the phonetic function through the new project. • Rehabilitate functional occlusion (occlusal stability, VDO, and guidances).32 • Offer periodontal protection and contouring before impression. • Check the correction of preparations guided by the mock-up. • Acquire oral hygiene techniques suitable for the restorations. • Offer constant access to the tooth structures during preprosthetic treatment. • By checking the width of the provisional restoration, the dentist can see whether or not the preparation was correct. In other words, provisional restorations must fulfill all the requirements of definitive restorations; the only difference is the material that is used.

In total rehabilitation, when realignment in a CR position is necessary, provisional restorations are crucial as they help to test the patient’s adjustment to the new position. In more than a few cases, repositioning the patient into CR is the only therapeutic solution (bruxism, reduced VDO, severe abrasion). Dentists should always test the new occlusion by using flawlessly adjusted and stable provisional restorations, built on casts mounted in the articulator according to accurate measurements of the expected position and guidance. In bridge restorations, chiefly on anterior teeth and including prosthetic rehabilitation on implants in multiple edentation, provisional restorations play a very significant part in creating pontic emergence profiles. First, the dental technician marks the model, and then the dentist adds successive layers of composite material in the area of gingival contact in order to create a concave soft tissue outline in the edentulous ridge mucosa. Sometimes it is even necessary to use a bur to form a small concave area on the edentulous ridge itself to achieve a more esthetic emergence profile of the pontic. This type of pontic is named an “ovate pontic” in the dental literature, and it requires the patient’s awareness of and willingness to maintain good hygiene. In certain clinical situations, provisional restorations may help interdental papilla reconstruction and gingival embrasure closing in circumstances in which the papillae display different heights, especially in the anterior region. One may visualize dental papillae as water balloons, the shape of which can be modified by applying pressure. The ideal distance between the contact point and the crest of the alveolar bone is 4.5 to 5 mm. The restoration should be positioned subgingivally, in agreement with periodontal measurements, and the patient must be recalled in 6 to 8 weeks for soft tissue reimpression.7,33 The aforementioned procedure requires the patient’s time and cooperation, so an excellent esthetic achievement regarding provisional restorations goes a long way towards maintaining good communication with the patient. Any changes made to the diagnostic wax-up/mock-up accepted by the patient must be faithfully reproduced in the provisional restoration. At the same time, all the elements included in the provisional restoration must also exist in the definitive restoration (wax-up/mock-up → copy/paste → provisional restoration → copy/paste → definitive restoration) (Figs 4-43 to 4.50). The dental literature describes four leading techniques for the fabrication of provisional restorations: • Direct technique.

• Indirect technique. • Modified indirect technique (Fradeani). • CAD/CAM technique. In general, irrespective of the technique used, provisional restorations must have several common features: • Easy to make. • Wide-ranging chromatic spectrum. • Low cost. • Fracture resistance when removed from the teeth. • Easy to remove from the teeth. • Satisfactory esthetics. • Medium-term wear resistance. • High resistance to mastication forces. • Good marginal fit. • Not irritate the periodontium. • Enable proper hygiene.

Fig 4-43 Initial situation.

Fig 4-44 Wax-up.

Fig 4-45 Mock-up.

Fig 4-46 Mock-up with horizontal guiding grooves.

Fig 4-47 Guided minimally invasive preparation.

Fig 4-48 Provisional restoration.

Fig 4-49 Definitive restoration.

Fig 4-50 Intraoral definitive restoration.

4.2.1 Direct technique Definition The provisional restoration is made by the dentist. Once the teeth have been prepared, the patient-approved wax-up is replicated by an indirect mock-up. A putty impression or thermoformed matrix and acrylic or composite resin are used (Fig 4-51).2,19,34

Fig 4-51 Thermoformed matrix: verifying the parallelism and the amount of the tooth preparation.

Stages VERSION A • Wax-up. • Indirect mock-up. • Changes, if required. • Putty impression of the wax-up, including the area under treatment and at least two other teeth on both sides of the prepared teeth.

• The putty impression is tried in the mouth and correct positioning is checked. • The impression is filled with resin in a matching color and fitted onto the teeth. • Instructions for use (curing time, setting time, etc) must be followed according to product and manufacturer. • Pay attention to the fact that all resins have exothermic curing reaction and, consequently, vital teeth may have a pulpal response to high temperatures. Water cooling is recommended during curing.35–37 • The resin usually undergoes some shrinkage during setting, therefore it should be moved from time to time during curing. • For a more esthetic result, it can be colored with pigments and glazed after polishing. • Temporary cementation material that is in harmony with the subsequent definitive cementation and the type of definitive restoration should be used for the provisional cementation of the restoration.38,39 Advantages • It is relatively easy, inexpensive, and does not involve the laboratory. • It supplies instant data on the thickness and parallelism of the tooth preparation.2,40 Disadvantages • Marginal imprecision. • The patient feels a strong exothermic reaction. • Contraindicated for multiple dental units. Version B • Wax-up. • Indirect mock-up. • Changes, if required. • Extra-hard stone replica of the wax-up. • Thermoformed matrix. • Matrix try-in in the oral cavity. • Matrix filled with resin. • Applying the matrix on the teeth. The rest of the stages are similar to version A.

Advantages • The presence and amount of dental structure reduction is better visualized through the matrix (it can also serve to guide preparation). • Indicates the presence or absence of resin imperfections. Disadvantages • More expensive technique, also involving the laboratory. • Longer fabrication time. The making of this provisional restoration is similar to that of the indirect mock-up with the exception that in this case the teeth are already prepared, while with the indirect mock-up they are not. 4.2.2 Indirect technique Definition The provisional restoration is made in the dental laboratory based on the impression taken by the dentist, the provisional restoration being the exact duplicate of one or several aforementioned preview procedures. Technique • Case preview. • Guided minimally invasive preparation. • High-quality putty arch impression (impression taken as a definitive restoration). • Impression of antagonist teeth, occlusion, and facebow record. • The common technique for provisional restoration of acrylic or composite resin in made in the laboratory. The advantage of previsualization is that it enables the accurate reproduction of size and volume in the provisional restoration. Advantages • Improved esthetics. • More accurate finishing than the direct technique. • Avoids the exothermic reaction during curing that occurs with the direct technique, and the

patient’s exposure to free monomers.41 Disadvantages • As a result of shrinkage during curing (lower in the composite resin compared to the acrylic), two major shortcomings arise: insertion on the abutments is difficult (the restoration feels “tight”), and undercontouring occurs at the cervical margin (either the shoulder is incompletely covered, or the restoration has no contact with it). • The aforementioned shortcomings have a negative impact on the marginal periodontium. • More work hours. • Higher cost because the laboratory is also involved.42–47 4.2.3 Modified indirect technique Definition This technique, also known as the “shell technique” – described in detail by Fradeani2 – involves a provisional restoration made in the dental laboratory that is subsequently relined by the dentist in the patient’s mouth.48,49 Technique • Until the stone cast is made, the steps coincide with the traditional indirect technique. • With a pencil, the technician marks an overextension of the margin on the stone cast beyond the dentogingival border of about 0.5 to 1 mm. Thus, the modeling wax will be extended to the gingival border. • Thereafter, a groove is made in the stone along the pencil line for a better definition of the overextended margins. • Once the provisional restoration has been finished in the traditional way, the technician makes it randomly larger. The result is a resin “shell” on the outside; it has the volume and color requested by the dentist, but on the prepared tooth it is very loose and friction free. At the same time, the “shell” has an overextension of 0.2 to 0.4 mm at the gingival border. • In the oral cavity, the dentist relines the “shell” with self-curing resin that will thus incorporate the entire margin. • Finally, the “shell” is finished and adjusted to the margin. Advantages • Marginal fit is undeniably superior to direct and traditional indirect techniques.

• Easy insertion. Disadvantages • The interproximal area is uncertain. • Difficulties in positioning it into the oral cavity.50 4.2.4 CAD/CAM technique The new computerized scanning and manufacturing technology enables the creation of provisional restorations with high margin precision.51–54 Direct technique If the practice uses the new computerized scanning and manufacturing technology, provisional restorations can be made either for a single-tooth restoration or for dental bridges. While the method is less indicated for a single-tooth restoration – because the final restoration can be made and cemented during the same session – it is more useful for bridges, where the dental laboratory is also involved. Ceramic block manufacturers do not recommend the use of this technology in dental bridge restorations, but they do for provisional restorations. The restoration can be made either by scanning the wax-up created in the laboratory and following the parameters of the template made by the dental technician after the dentist’s indications, or by direct computerized modeling in the dental practice. This technique is a favorite choice in many clinical situations because provisional restorations can be quickly executed: they help the patient to adjust to the abutment, and they give the patient and the dentist the opportunity to discuss the esthetic aspects of the restoration. Indirect technique The technology allows the scanning of the stone cast; ie, the diagnostic wax-up model. On the basis of the acquired information, an excellent result can be achieved. Provisional restorations that are done this way are usually well-received by the patient as they are highly accurate with respect to both marginal fit and volume (Figs 4-52 to 4-54).

Fig 4-52 Wax-up scanning.

Fig 4-53 Stone cast scanning.

Fig 4-54 Superposition of scans.

REFERENCES 1. Greenwall L, Jameson C. Success Strategies for the Aesthetic Dental Practice. London: Quintessence, 2008. 2. Fradeani M. Prosthetic Treatment – A Systematic Approach to Esthetic, Biologic, and Functional Integration, vol 2. Chicago: Quintessence, 2008. 3. Chice GJ, Pinault A. Esthetics of Anterior Fixed Prosthodontics. Chicago: Quintessence, 1994. 4. Reshad M, Cascione D, Magne P. Diagnostic mock-ups as an objective tool for predictable outcomes with porcelain laminate veneers in esthetically demanding patients: A clinical report. J Prosthet Dent 2008;99:333– 339. 5. Spear FM. The maxillary central incisor edge: A key to esthetic and functional treatment planning. Compend Contin Educ Dent 1999;20:512–516. 6. Dietschi D. Free-hand composite resin restorations: A key to anterior aesthetics. Pract Periodont Aesthet Dent 1995;7:15–25. 7. Zuhr O, Hurzeler M. Plastic-Esthetic Periodontal and Implant Surgery. Chicago: Quintessence, 2012. 8. Walder JF, Freeman K, Lipp MJ, Nicolay OF, Cisneros GJ. Photographic and videographic assessment of the smile: Objective and subjective evaluations of posed and spontaneous smiles. Am J Orthod Dentofacial Orthop 2013;144:793–801. 9. Ahmad I. Protocols for Predictable Aesthetic Dental Restoration. Oxford: Blackwell Munksgaard, 2006. 10. Dalvit DL, Parker MH, Cameron SM. Quick chairside diagnostic wax-up. J Prosthet Dent 2002;87:581–582. 11. Shillingburg HT Jr, Hobo S, Whitesett LD, Jahobi R, Brackett SE, Fundamentals of Fixed Prosthodontics, ed 3. Chicago: Quintessence, 1997:11–24. 12. Okeson JP. Management of Temporomandibular Disorders and Occlusion, ed 4. St Louis: Mosby, 1998. 13. Dawson P. Functional Occlusion from TMJ to Smile Design. St Louis: Mosby, 2007. 14. Buduru S, Almasan O. Notiuni practice de ocluzologie. Cluj: Napoca Star, 2010. 15. Kahng LS. Patient–dentist–technician communication within the dental team: Using a colored treatment plan wax-up. J Esthet Restor Dent 2006;18:185–195. 16. Rufenacht CR. Fundamentals of Esthetics. Chicago: Quintessence, 1990. 17. Kano P. Challenging Nature: Wax-Up Technique in Aesthetics and Functional Occlusion. London: Quintessence, 2011. 18. Rosenstiel SF, Land MF, Fujimoto J. Contemporary Fixed Prosthodontics, ed 3. St. Louis: Mosby, 2001. 19. Gürel G. The Science and Art of Porcelain Laminate Veneers. Chicago: Quintessence, 2003. 20. McLaren EA. Bonded functional esthetic prototype: An alternative pre-treatment mock-up technique and costeffective medium-term esthetic solution. Compend Contin Educ Dent 2013;34:596–607. 21. Magne P, Belser U. Bonded Porcelain Restorations in the Anterior Dentition. A Biomimetic Approach. Chicago: Quintessence, 2002. 22. Kois DE, Schmidt KK, Raigrodski AJ. Esthetic templates for complex restorative cases: Rationale and management. J Esthet Restor Dent 2008;20:239–250. 23. Gürel G., Bichacho N. Permanent diagnostic provisional restorations for predictable results when redesigning smiles. Pract Proced Aesthet Dent 2006;18:281–286. 24. Coachman C, Calamita M. Digital Smile Design: A tool for treatment planing and comunication in esthetic

dentistry. QDT 2012:35:103–111. 25. Burns DR, Beck DA, Nelson SK. A review of selected dental literature on contemporary provisional fixed prosthodontic treatment: Report of the Committee on Research in Fixed Prosthodontics of the Academy of Fixed Prosthodontics. J Prosthet Dent 2003;90:474–497. 26. Patras M, Naka O, Doukoudakis S, Pissiotis A. Management of provisional restorations’ deficiencies: A literature review. J Esthet Restor Dent 2012;24:26–39. 27. Regish KM, Sharma D, Prithviraj DR. Techinques of fabrication of provisional restoration: An overview. Int J Dent 2011. doi: /10.1155/2011/134659. 28. Ireland MF, Dixon DL, Breeding LC, Ramp MH. In vitro mechanical property comparison of four resins used for fabrication of provisional fixed restorations. J Prostht Dent 1998;80:158–162. 29. Dubois RJ, Kyriakakis P, Weiner S, Vaidyanathan TK. Effects of occlusal loading and thermocycling on the marginal gaps of light-polymerized and autopolymerized resin provisional crowns. J Prosthet Dent 1999;82:161– 166. 30. Qualtrough AJE, Satterthwaite JD, Morrow LA, Brunton PA. Principles of Operative Dentistry. London: Blackwell Munksgaard, 2005. 31. Donovan TE, Cho GC. Diagnostic provisional restorations in restorative dentistry: The blueprint for success. J Can Dent Assoc 1999;65:272–275. 32. Orthlieb JD. Gnathologie fonctionnelle, vol 2: Occlusion et Reconstruction Prothetique. Paris: Wolters Kluwer, 2011. 33. Tarnow DP, Magner AW, Fletcher P. The effect of the distance from the contact point to the crest of bone on the presence or absence of the interproximal dental papilla. J Periodontol 1992;63:995–996. 34. Higginbottom FL. Quality provisional restorations: A must for successful restorative dentistry. Compend Contin Educ Dent 1995;16:442,444–447. 35. Ogawa T, Aizawa S, Tanaka M, Matsuya S, Hasegawa A, Koyano K. Effect of water temperature on the fit of provisional crown margins during polymerization. J Prosthet Dent 1999;82:658–661. 36. Michalakis K, Pissiotis A, Hirayama H, Kang K, Kafantaris N. Comparison of temperature increase in the pulp chamber during the polymerization of materials used for the direct fabrication of provisional restoration. J Prosthet Dent 2006;96:418–423. 37. Castelnuovo J, Tjan AHL. Temperature rise in pulpal chamber during fabrication of provisional resinous crowns. J Prosthet Dent 1997;78:441–446. 38. Christensen GJ. Provisional restorations for fixed prosthodontics. J Am Dent Assoc 1996;127:249–252. 39. Passon C, Goldfoge IM. Direct technique for the fabrication of a visible light-curing resin provisional restoration. Quintessence Int 1990;21:699–703. 40. Ahmad I. Predetermining factors governing calculated tooth preparation for anterior crowns. QDT 2001;24:57–68. 41. Hansen PA, Sigler E, Husemann RH. Making multiple predictable single-unit provisional restorations using an indirect technique. J Prosthet Dent 2009;102:260–263. 42. Hazelton LR, Brudvik JS. A new procedure to reinforce fixed provisional restorations. J Prosthet Dent 1995;74:110–113. 43. Hansen PA, Sigler E, Husemann RH. Making multiple predictable single-unit provisional restorations using an indirect technique. J Prosthet Dent 2009;102:260–263.

44. Burke FJ, Murray MC, Shortall AC. Trends in indirect dentistry: 6. Provisional restorations, more than just a temporary. Dent Update 2005;32:443–444, 447–448, 450–452. 45. Luthardt RG, Stossel M, Hinz M, Vollandt R. Clinical performance and periodontal outcome of temporary crowns and fixed partial dentures: A randomized clinical trial. J Prosthet Dent 2000;83:32–39. 46. Tjan AH, Castelnuovo J, Shiotsu G. Marginal fidelity of crowns fabricated from six proprietary provisional materials. J Prosthet Dent 1997;77:482–485. 47. Small BW. Indirect provisional restoration. Gen Dent 1999;47:140–142. 48. Ozcelik TB, Yilmaz B. A modified technique for the fabrication of fixed interim restorations. J Prosthet Dent 2008;100;328–329. 49. Ferencz JL. Fabrication of provisional crowns and fixed partial dentures utilizing a “shell” technique. N Y J Dent 1981;51:201–206. 50. Simeone P, Pilloni A. Temporary crowns: Repositioning key as a new technical approach in the clinical relining phase. J Esthet Restor Dent 2004;16:284–289. 51. Perry RD, Magnuson B. Provisional materials: Key components of interim fixed restorations. Compend Contin Educ Dent 2012;33:59–60, 62. 52. Kurbad A. CAD/CAM-based polymer provisionals as treatment adjuncts. Int J Comput Dent 2013;16:327– 346. 53. Gürel G, Shayder A, Paolucci, Braulio; Bichacho N. Anterior Esthetics with APT: Are CAD-CAM Systems Ready for the High-End Anterior Esthetics Challenge? QDT 2013;36:77. 54. Stawarczyk B, Sener B, Trottmann A, Roos M, Özcan, Hammerle CHF. Discoloration of manually fabricated resins and industrially fabricated CAD/CAM blocks versus glass-ceramic: effect of storage media, duration, and subsequent polishing. Dent Mater J 2012;31:377.

CAMELIA ALB FLORIN ALB

Chapter V CERAMICS USED IN ESTHETIC RESTORATIONS

CERAMICS USED RESTORATIONS

IN

ESTHETIC

Introduction Ceramics are currently the only materials capable of reproducing the natural qualities of human teeth as perfectly as possible, and are also the most biocompatible of all dental materials. However, two obstacles have limited the application of all-ceramic systems in all types of restorations for quite some time: their low flexural resistance, and the laboratory technology needed, which is far more complex and time consuming than with metal-ceramic or composite restorations.1 The important progress made over the past two decades – especially the improvement of the mechanical properties of high-strength ceramics and the development of new, simplified laboratory procedures – have led to better reproducibility of all-ceramic restorations. This has increased their clinical use over the metal-ceramic technique by over 50% in some countries. The trend is to continually extend the application of all-ceramic systems in all fields of dentistry – both for their esthetic results, as well as for the reduced manufacturing costs, which are currently lower for a CAD/CAM-produced, all-ceramic crown than for a metal-ceramic one.2 We can confidently assert that in due course all-ceramic systems will dominate restorative dentistry. Numerous ceramic systems have appeared in recent years, from the most conservative ones that can be used even without any tooth preparation, to those with applications in extended edentulous spaces. These systems have different properties and use different laboratory materials and technologies. They therefore have diverse clinical indications, which could become confusing for the general practitioner who is not an expert in the field of dental materials. This chapter provides details on the existing ceramic systems and how they are used in clinical practice. Its aim is to help practitioners to better understand the all-ceramic systems that are currently available.

5.1 WHAT IS DENTAL CERAMIC? 5.1.1 A short history The term “ceramic” is of Greek etymology, deriving from “keramos”, which means “burnt clay”. The basic components of ceramic used to be clays (argils), which produced solid (but brittle) objects, such as ceramic pots, when heated in a furnace. The technology for manufacturing porcelain (the most noble of ceramic products) was developed in China in 2697 BC and reached Europe (via Venice) only at the end of the 15th century.3 The first attempts to manufacture artificial ceramic teeth for dentures are attributed to the French pharmacist Alexis Duchateau in 1774. In 1844, Samuel Stockton White started the large-scale production of ceramic teeth for removable dentures in Philadelphia, USA. In 1886, Charles H Land (known as the father of porcelain dentistry) made the first ceramic inlay on a platinum foil after an impression had been taken in a patient’s mouth. In 1903 in Detroit, Land also produced the first full-coverage ceramic crown (the jacket crown) made of a high-fusing ceramic fired on a platinum foil over a die, which had very low fracture resistance and was recommended only for anterior teeth. At the beginning of the 20th century, the results with these ceramic products were poor, mainly due to insufficient knowledge regarding their properties and behavior. This led to flaws appearing during the sintering process and a lack of adhesion between ceramic restorations and the dental tissues. Furthermore, weak phosphate cements were being used to lute them. Their popularity declined even more in the 1940s with the discovery of acrylic resins. Ceramics were less and less used until clinical failures of acrylic resins began to appear (eg, reduced resistance to wear and color changes over time). In 1962, Weinstein and Weinstein patented a new type of ceramic based on leucite, an aluminosilicate with a high coefficient of thermal expansion (CTE). This discovery made the ceramic CTE closer to the CTE of the alloy, leading to metal-ceramic fixed restorations with improved properties. Therefore, the 1960s are considered the beginnings of metal-ceramics.4 An important step in improving the esthetic properties of ceramics was the introduction of ceramic sintering under a vacuum, which reduced the porosity and led to a more homogeneous product with a higher translucency. 5.1.2 Structure and properties of ceramics

Ceramic is an inorganic material made of metal elements (Al, Ca, Mg, K) and non-metal elements (Si, O, B, F) which form oxides, nitrides, borides, or silicates, as well as complex mixtures of these materials. The intermolecular bonding in ceramics can be ionic or covalent; their different proportions producing changes in their chemical properties. Most ceramics (not only dental porcelain) are obtained by heating up a powder, or a liquid in which powder particles have been dissolved, to a temperature where the particles will merge, forming a solid mass. The result is a class of materials with specific properties: high fusing temperatures, strength, rigidity (although brittle), high abrasion resistance (but weak in tension), high compression resistance, and good electrical and thermal insulators. These materials can be modified through additives, thus obtaining an infinite range of colors.5 The clinical relevance of the molecular structure of ceramics is reflected in the optical properties of each ceramic type: when the glass matrix (the noncrystalline phase) dominates, the ceramic will be more translucent, and vice versa; ie, when the crystalline content is higher, the ceramic will be more opaque.6 Generally, when dentists use the word “ceramic,” it refers only to a limited class of materials used for indirect prosthetic restorations. It is important to note that, based on structure and properties, there are other examples of “unconventional” ceramics with a range of applications in dentistry, such as ceramics used in the composition of investment materials, as inorganic fillers for composite resins, or glass-ionomer cements (GICs).5 5.1.3 The composition of dental ceramics The ceramics for general use in cookware, computer parts, and heat shields in vehicles are argil ceramics (also known as “pottery ceramics” or clays). These are composed of three basic elements: feldspar (the main component); quartz, and kaolin in various percentages. Dental porcelain is different from ceramics in general use, and although initially it used to contain a small percentage of kaolin (4% to 5%), this has been completely eliminated in modern ceramics. As with the majority of glass products, dental ceramics contain minerals such as feldspar (K2OAl2O36SiO2) (80%); important quantities of silica, the most widespread mineral on earth (SiO2) (14% to 18%); reduced quantities of alumina (Al2O3) (2%); and traces of other oxides that significantly influence their properties. In addition to the basic components, other substances are found in dental ceramics:

• Pigments providing the color of the ceramic: titanium oxide for yellow/brown shades; manganese oxide for violet; iron oxide for brown; copper oxide for green; and cobalt oxide for blue. • In the past, uranium oxides used to be added to obtain the fluorescence of ceramic, but because of their reactivity, they have been replaced with lanthanide oxides.7 To conclude, modern dental ceramics have two basic components: an amorphous glass matrix – made of the silica network – and a crystalline phase. The latter determines the mechanical, physical, chemical, and optical properties of dental ceramics. The ratio between the two components varies; the higher the glass content, the higher the translucency, but the lower the resistance to crack propagation. Generally, the ceramic used for all-ceramic systems will contain between 35% and 90% of the crystalline phase, for improved mechanical properties.7 The first generations of feldspathic ceramics (known today as conventional or traditional feldspar ceramics) had several disadvantages: a sintering contraction higher than 40%; a high fracture risk (therefore they were used only for anterior teeth); and a low flexural resistance. They were, however, also very hard and rigid, although brittle. New techniques, as well as materials with increased resistance to tension and flexion, have been researched and developed. 5.1.4 Properties of dental ceramics Mechanical properties • Very high elasticity modulus (alumina = 380 MPa). • High compression strength (150 to 900 MPa). • Low resistance to traction (20 to 60 MPa). • Lacks resistance to fracture. • The maximum plastic deformation it can withstand is 0.1%. • These materials are extremely sensitive to surface microcracks. • The hardness of conventional ceramics was 460 to 660 VHN (Vickers hardness number), so they used to be harder than natural tooth enamel, generating the abrasion of opposing teeth. The new ceramics with low fusing temperatures have values of 380 VHN, very close to natural enamel. The ceramics used for the core (eg, alumina) have a hardness of 1,200 VHN, which is why they are always covered by a feldspar or vitreous ceramic.5

• Average density equals 1.0 to 3.8 g/cm3 – the density determines the weight of a ceramic restoration (which is less than the weight of a metal structure). • Ceramic is a refractory material with a very high fusing temperature. • The coefficient of thermal expansion (CTE) has reduced values: 1 to 15 × 10-6/°C. This is an advantage for the all-ceramic crowns as it acts as a good insulator, but becomes an inconvenience for metal-ceramic crowns. This is why low-fusing ceramics are used, with a melting temperature of about 100°C to 200ºC lower than the solidus temperature of the alloy. The optical properties of ceramics greatly interest patients because they directly correlate with the esthetic result. As mentioned in the section on the composition of dental ceramics (5.1.3), translucency decreases with more crystalline phase. Thus, the best optical properties belong to the glass ceramics (Empress, Dicor), as well as the feldspathic ceramics, as translucency is lower and opaqueness higher for more resistant ceramics with a greater crystalline phase – such as the infiltrated ceramics (spinell, alumina, zirconia).6 The chemical properties • Ceramics have low reactivity and are considered an inert material in the oral environment. • Ceramics are not affected by large variations in oral pH, ie, they are not attacked by acids that exist in the oral cavity.5 Biological properties • Ceramics are dental materials with a very good biocompatibility, being almost totally inert to the tissues of the oral cavity. Glazed ceramic is a plaque-resistant material and is thus periodontally friendly.

5.2 CERAMICS USED IN DENTISTRY As there are many all-ceramic systems on the dental materials market, several classifications have been made in an attempt to organize them. Criteria used for classifications were: the fusing temperature; ceramics composition; laboratory technology; and their clinical indications. Classification based on the fusing temperature • High fusing temperature – over 1,300°C. • Average fusing temperature – 1,100°C to 1,300°C. • Low fusing temperature – 850°C to 1,100°C. • Very low fusing temperature – 680°C to 850°C.7 Classification based on ceramic composition • Category 1 – glass-ceramics (contain mainly silica or quartz). • Category 2 – glass-ceramics with crystalline filling (usually leucite or another type of high-fusing temperature glass). • Category 3 – crystalline ceramics with glass fillers (mainly alumina). • Category 4 – polycrystalline ceramics (alumina and zirconia).8 Classification based on laboratory technology Additive systems: • Layering technique (Optec HSP, Vitadur, Duceram LFC). • Castable ceramics (Cerapearl, Dicor). • Infiltration and sintering (In-Ceram). • Pressing technique (PS Empress, Cerestore, Optec, OPC, Cerapress). Subtractive systems: • Mechanical milling. • Computerized milling: CAD/CAM. Classification based on their clinical indications • Veneering ceramics – generally layered over the metal structure or an oxide ceramic core. • Ceramics for the framework of removable partial dentures.

• Ceramics for suprastructures on implants. The authors have decided to describe in detail only two of the classifications after Giordano and McLaren,8 believing that these will facilitate the understanding of the differences between the various ceramic systems. 5.2.1 Types of ceramics based on their microstructure There are four large classes: • Category 1 – glass-ceramics (contain mainly silica). • Category 2 – glass-ceramics with crystalline fillers (usually based on leucite or another type of glass with a high fusing point). • Category 3 – crystalline ceramics (mainly alumina with a glass matrix). • Category 4 – polycrystalline ceramics (alumina and zirconia).9 5.2.1.1 Amorphous glass-ceramics Amorphous glass-ceramics contain mainly silica (known as quartz) with different amounts of alumina – aluminosilicates. They have weak mechanical properties: the resistance to flexion is 60 to 70 MPa, which is why they are generally used as veneering material for metal-ceramics (traditional feldspar ceramics) or other ceramic frameworks (over high-strength ceramic copings). This ceramic is also used for fabricating laminate veneers on refractory dies or through the platinum foil technique. 5.2.1.2 Glass-ceramics with secondary crystalline phase The glass matrix is identical to that in amorphous glass-ceramics, the difference being the amount and the type of crystals introduced in the ceramic, or grown in the glass phase. The most commonly used ceramic crystals today are leucite, lithium disilicate, and fluorapatite.8,10 These materials are used in blocks for the CAD/CAM technique for CEREC (Sirona Siemens) – Vitablocs Mark II (Vita Zahnfabrik) – because they have the lowest failure rate in inlays and onlays (approximately 1% per year) (Figs 5-1a to 5-1c). Low-leucite content ceramics Low-leucite content ceramics – often incorrectly called feldspar ceramics – are used as veneering materials over the metal framework, over ceramic copings, or for ceramic veneers

using the refractory die technique. The first ceramic powder introduced on the market had a variable size and distribution of leucite crystals, and had a very low flexural resistance. The new materials contain a homogeneous distribution of leucite crystals, being less abrasive and having a high flexural resistance. These materials are used especially for producing metalceramic crowns, an example being Vita VM 13 (Vita Zahnfabrik)9 (Figs 5-2a to 5-2d).

Fig 5-1 a–c Clinical case: IPS e.max crown on tooth 21. (Images courtesy of Dr Florin Lăzărescu.)

High-leucite content glass-ceramics High-leucite content glass-ceramics (approximately 50%) start as a glass matrix around some leucite crystals. At the second thermal treatment, they grow in size and form crystals that will block crack propagation, thus improving their mechanical and physical properties, such as high resistance to fracture (120 MPa). These materials are better known under their commercial names, such as: Empress (Ivoclar Vivadent), Finesse (Dentsply), PM9 (Vita), as well as Empress CAD milling blocks used for CEREC and E4D (Figs 5-3a and 5-3b).

Fig 5-2 a–d Clinical case before and after cementation of metal-ceramic crowns.

Lithium disilicate-based glass-ceramic Lithium disilicate-based glass-ceramic, with a 70% crystalline component and a higher resistance to flexion (around 360 MPa), was first introduced by Ivoclar as Empress II. It is currently available as IPS e.max, with two versions: one for pressing, and the other for CAD/CAM milling. Although it has a high ratio of crystalline phase, the material is translucent enough to be used in esthetic restorations (veneers, crowns) because of the low refraction index of the lithium disilicate crystals. Furthermore, because of its high mechanical resistance, it can be used as a ceramic core that will be layered with a special ceramic containing fluorapatite crystals.

Fig 5-3 a, b Clinical case before and after cementing of an Empress ceramic bridge 32 to 42. (Images courtesy of Dr Ionut Brânzan.)

5.2.1.3 Crystalline ceramic with interpenetrating phase Crystalline ceramic with an interpenetrating phase was introduced in 1988 by the Vita Company as the InCeram system, which contained at least two components that intertwined and expanded from depth to surface. First, a porous matrix was obtained, which was later “saturated” with the second-phase glass (lanthanum aluminosilicate glass) through capillarity. This system was introduced as an alternative to the metal-ceramic because it has a highstrength ceramic core (350 to 650 MPa flexural resistance)10 that can be layered with veneering material (VM). Today, these crystalline alumina copings can be produced either by sintering the alumina onto a duplicated die, or by milling it in a CAD/CAM machine (Vita InCeram Alumina for inLab). 5.2.1.4 Single-phase polycrystalline ceramics Single-phase polycrystalline ceramics contain only one crystalline component and are obtained by the sintering of the crystals that do not have a glass matrix, such as aluminum oxide (alumina) and zirconium dioxide (zirconia). This system was first introduced by Procera (Nobel Biocare); the ceramic powder being compressed, then milled and sintered at 1,600°C, generating a very thick and resistant core (600 MPa), but with a 20% contraction after sintering, which leads to a poor marginal fit. Another single-phase ceramic is zirconium dioxide, which is not used in its pure form, but is partially stabilized by the addition of other oxides – the majority of zirconium dioxide-based ceramics used in dentistry contain a 3% addition of yttrium.11 Its resistance to flexion is about 900 to 1,100 MPa, higher than any other

dental ceramic, so extended restorations can be made, including full bridge, complex dental implant-supported frameworks. Partial removable dentures can also be produced, even in functional stress areas, just like metal frameworks12 (Figs 5-4a to 5-4d and 5-5a and 5-5b). Practical applications Some practical applications of the classification based on microstructures are: • The ceramics from categories 1 and 2 can be etched with hydroflouric acid, so they can create a better adhesive bonding, while those from groups 3 and 4 cannot be etched, so their adhesive forces are lower (Figs 5-6a to 5-6d and 5-7a to 5-7d). • The glass content in a ceramic material makes it more transparent, which means it can be used in the esthetic area, although it has a lower flexural resistance. On the opposite end of the spectrum, polycrystalline solids have the best mechanical properties, but they are very opaque and are therefore mainly used as the core or infrastructure in extended bridges, as well as in functional stress areas with other veneering ceramics.8,9

Fig 5-4 a–d Clinical case before and after the IPS e.max crown on tooth 11. (Images courtesy of Dr Ionut Brânzan).

Fig 5-5 a, b Clinical case before and after cementing InCeram crowns on teeth 21 and 22. (Images courtesy of Dr Ionut Brânzan).

Fig 5-6 a–d Clinical case before and after cementing microveneers on the maxillary incisors.

Fig 5-7 a Laminate veneers made on refractory dies.

Fig 5-7 b e.max Press crowns

Fig 5-7 c Full zirconia crown.

Fig 5-7 d InCeram crowns.

5.2.2 All-ceramic systems based on fabrication technology The most relevant classification of the current ceramic systems is the one based on laboratory technology, comprising four classes: 1. Powder/liquid systems processed through layering on refractory models or on a platinum matrix. 2. Pressable ceramic. 3. Crystalline ceramics obtained by glass infiltration of porous structures. 4. CAD/CAM technology. 5.2.2.1 The refractory die technique This is the oldest ceramic system (dating back to 1886). It is considered a “hand-made” ceramic, as opposed to the “machine-made” systems, eg, CAD/CAM. It has been used for quite a long period of time because of its advantages: • It does not require any special laboratory technology and it uses conventional feldspar ceramic, similar to the one used for the porcelain-fused-to-metal (PFM) technology, and the same ceramic furnace. • It allows for a very conservative preparation – 0.3 to 0.4 mm thickness laminate veneers can be fabricated through this procedure. • The esthetic results are exceptional because the feldspar ceramic is pure glass and has the best translucency, closely imitating natural enamel; without metal or ceramic coping, layering can be made on all the restoration thickness, thus obtaining the depth effects. • It can be etched with hydroflouric acid, creating strong bonding between ceramic and

dental tissue13,14 (Figs 5-8a to 5-8h).

Fig 5-8 a Special Willi Geller alveolar model with removable dies.

Fig 5-8 b Ceramic layering with Vita VM 7 ceramic (Vita) on refractory dies.

Fig 5-8 c Ceramic sintered directly on refractory dies in the ceramic furnace.

Fig 5-8 d Ceramic veneers after sintering on the refractory dies.

Fig 5-8 e, f Ceramic veneers removed from the refractory dies by sandblasting at a very low pressure; from this moment onward, no corrections are possible for the veneers.

Fig 5-8 g, h The final ceramic veneers ready to be sent to the dental office.

The disadvantages of this system are: • An extremely sensitive fabrication technique both for the dentist (veneers are very fragile before adhesive luting) and the dental technician (no corrections are possible after the try-in stage). • They require three different models for one case, so the technique is laborious. • The flexural resistance of the feldspar ceramic is the lowest of all the current systems, being under 100 MPa. In conclusion, this technique has become reserved for porcelain veneers only, especially in the prep-less or very conservative cases, where most of the preparation is in enamel. For cases with severe endodontic discolorations, with extended crown destruction or with traumatic occlusions, there are other ceramic systems with increased resistance that also give a good esthetic result. Steps in fabricating a ceramic veneer on refractory die

Steps in fabricating a ceramic veneer on a refractory die include: • A conservative preparation of the treated teeth, which must be guided through a bonded mock-up or a silicone guide obtained after the smile design, and the diagnostic wax-up. • Fabricating of few specific models: one cast with removable dies made in special gypsum, with a root part and anti-rotational grooves; these dies are then duplicated into removable dies made of refractory material (investment material). A second model is a solid cast required for mounting in the articulator. The third model is the alveolar model after the Willi Geller technique, in which the plaster, removable die, and the duplicated dies can be repositioned.14,15 • Ceramic is layered on the duplicate removable dies until the natural anatomy of the tooth is restored; it is then sintered in the ceramic furnace together with the refractory die. • The investment material is removed from the veneer by sandblasting with 25 to 50 µm sand, which will not affect the marginal fit of the ceramic restoration. After the try-in in the patient’s mouth, the veneer is adhesively bonded with light-curing resin cements, as detailed in the adhesive luting protocol for all-ceramic restorations presented in Chapter XI. 5.2.2.2 Pressed ceramic systems These are probably the most widely used all-ceramic systems worldwide due to the lost-wax technique that has been mastered and is loved by dental technicians everywhere, the inexpensive laboratory technology, and the versatility of the current systems, which are able to fabricate all types of ceramic restorations (from the smallest veneer to posterior bridges). The first generation of pressable ceramics contained glass-based ceramics enriched with leucite crystals (35% to 40% crystalline content). The flexural resistance was double the resistance of feldspar ceramic, with a void ratio of 9%, and was indicated in single-tooth restorations: inlays, onlays, crowns, and veneers.6 The new generations have a higher percentage of the crystalline phase (65%) and a void ratio of 1%. The result is a material with an interconnected network of crystals in a glass matrix, which develops tangent compressive forces around the crystals leading to an increase of the mechanical strength and a limitation of the cracks (because of the differences between the CTE of the two phases). The resistance to fractures in the second generation of ceramics is double that of the first generation, and four times higher than in traditional ceramics.16,17 The most famous example of pressed ceramic is the IPS Empress system (Ivoclar Vivadent), which was introduced more than 20 years ago, with all its subsequent variations, out of which more than 37 million restorations had been made by 2010. All the systems that press the

ceramic use the same laboratory technology. On the plaster model, patterns are made from wax either to the full size of the restoration, or to a reduced dimension – called a core. The sprue is then attached and the wax pattern is invested in a refractory material. The wax is eliminated from the mold, after which the ceramic is heated at a high temperature and injected/infused into the obtained mold.18

Fig 5-9 a, b e.max Press onlay before and after external painting.

Fig 5-9 c, d Wax pattern of two fully contoured crowns.

Fig 5-9 e, f Investing the wax pattern for pressed ceramic.

Fig 5-9 g, h Removing the pressed crowns from the investment material. The result is two all-ceramic crowns attached to the pressed ceramic cone.

Steps in fabricating a pressed ceramic restoration through the IPS Empress 2 system • The teeth are prepared following the general rules for all-ceramic restorations and the impression is taken with polyvinyl siloxanes (PVSs) or polyethers. • Specific models in the laboratory are poured, with and without removable dies and an alveolar model (Figs 5-9a to 5-9h). • The wax pattern is fabricated on the cast in two different sizes:

Fig 5-9 i Pressed full-contour crowns on the model.

Fig 5-9 j Crowns after cut-back technique (removing a ceramic layer from the labial incisal third) to provide space for layering with feldspar powder ceramic (e.max Ceram).

Fig 5-9 k, l Cut-back pressed ceramic crowns with fluorescence properties resembling the natural tooth.

Fig 5-9 m, n Ceramic ingots Impulse Value – they have been on the market since 2012 and have a similar fluorescence to that of natural teeth. Layering the e.max Ceram powder effects and individualizing the labial surface of the crowns.

– as a core (undersized) with 0.2 to 0.5 mm space left for the final layering for individualization. – as the final restoration, in accordance with the real size and morphology of the restored

tooth. Only the surface colorations and the glaze are applied. (Figs 5-9i to 5-9n). • The wax pattern is immersed in a special phosphate-based investment material, thus producing the refractory mold. The mold is inserted into a special furnace for the pre-heating and heating treatment. • In the special injection furnace, the mold and the ceramic ingots are introduced. These are available in five degrees of translucency: high translucency (HT), low translucency (LT), medium opacity (MO), high opacity (HO), and the value and opal special shades. These various options for translucency have improved the final esthetic results considerably. The ceramic ingots are heated, then pressed into the mold under pressure. • After pressing, the ceramic piece is removed from the investment material, resulting in: – A restoration reproducing the final form and morphology, where the characterization is obtained only by external painting. This technique was mainly used in the first generation of these materials, and is still used in posterior teeth, inlays, onlays, and single crowns. – A coping of undersized proportions, over which the VM e.max Ceram is layered. This technique is mainly used in the esthetic area, for veneers, crowns, and bridges in the anterior area (Figs 5-9o to 5-9r).

Fig 5-9 o, p Empress veneers that are reduced in the labial third from the wax pattern stage, in order to allow a final individualization with ceramic powder.

Fig 5-9 q, r Applying ceramic powder effects and the final appearance on the master model.

The space for final esthetic layering is obtained through the cut-back technique applied at one of two different stages in the technological process: • Option 1: A full-size pattern of the ceramic crown is made in wax; it is invested and the

ceramic is pressed; thereafter the space is cut back from the pressed crown. • Option 2: The wax pattern is made in the final form and shape of the crown; the cut-back technique is done at this stage, thus investing an undersized pattern; it is then pressed, the result being an undersized restoration, on top of which the feldspar ceramic is layered. If the first Empress generations were indicated only for inlays, onlays, veneers, and crowns, the last generation – e.max Press – have almost generalized applications. They can be used for mini-veneers, occlusal veneers, table-tops, inlays, onlays, anterior and posterior crowns, and three-unit bridges in both the anterior and posterior areas (except for the molar area). These ceramics are good for over-pressing on galvano-formed crowns or prefabricated metal abutments, single implants in the anterior and posterior area, three-unit bridges up to the second premolar, or telescopic crowns. This system is not meant for bridges in the posterior area, long-span bridges, subgingival margins of the preparation, extended edentulous spaces, bruxism, cantilever bridges, and Maryland bridges.19 For long-span bridges in the premolar/molar area, the only ceramic that is resistant enough is zirconium dioxide, but even here the glass-ceramic e.max Press finds its applications, because these ingots can be pressed over zirconia frameworks for superior esthetics. 5.2.2.3 Crystalline ceramics obtained by glass infiltration of porous structures The most famous member of this family is the InCeram system, which was introduced by the Vita Company in Germany in 1988. The concept was developed by Sadoun in 1985, based on the PFM technique. Sadoun discovered that the alumina core had a flexural resistance three times higher than any other known system.20 InCeram uses a high-strength oxide ceramic coping made of alumina or magnesium, which is later infiltrated with a lanthanum aluminosilicate glass. Over this core, a veneering ceramic is layered and sintered in a technique very similar to the PFM technique. This is why the system was received with great enthusiasm by technicians after 1990, having proven very successful in all types of ceramic esthetic restorations: veneers, inlays, onlays, single crowns both in the anterior and posterior teeth, and even in short-span bridges, with a success rate at 3 years of 98% for anterior teeth and 94% in the premolar/molar area.21,22 The different systems allow many applications, as follows: • The first system – the InCeram Alumina (with a crystalline matrix of Al2O3) had increased

resistance to flexion (450 to 500 MPa) and an average translucency, so it could be indicated for crowns on anterior and posterior teeth. • InCeram Spinell (with magnesium oxide and alumina matrix) is the most translucent system, and with an average mechanical strength of 350 MPa, can only be used for crowns in the esthetic area. • InCeram Zirconia, with 30% alumina matrix and 70% zirconia, is the most resistant system (650 MPa flexural strength), but at the same time is also the most opaque, being used mainly in three-unit bridges in the premolar/molar area.21 • The fourth system – the InCeram Celay – is a subtractive one, producing the ceramic coping by mechanical milling (Vita Celay), then infiltrating it with aluminosilicate glass, and veneering it to restore the final tooth morphology and color. The steps in making an InCeram Alumina crown The PVS impression of the working arch, and the fabrication of special casts in the laboratory according to the technique described in the refractory die technique, consists of the following steps: First the alumina suspension is prepared by mixing the alumina powder with the specific liquid, under vacuum and in the ultrasound bath. This suspension is applied onto the duplicated die, and the excess is reduced with a scalpel blade to a thickness of 0.7 mm occlusal and 0.5 mm on the axial walls. The structure is very fragile and brittle. Sintering the alumina core is achieved on the removable die in a special InCeramat furnace for 10 hours at 1,120°C. The alumina core produced after this first sintering is very fragile and porous, with a whitechalky appearance. Now, adjustments can be made using diamond burs, at low speed. Any cracks in the alumina coping can be detected using magnification and a special blue dye. The porous coping is then infiltrated with lanthanum aluminosilicate glass by depositing the coping onto a platinum foil. The glass will infiltrate by capillarity into the spaces between the alumina-oxide particles. It is then sintered at up to 1,100°C for 4 to 5 hours. Removal of the excess glass is done using high-strength stone burs and sandblasting with Al2O3 sand (35 to 50 µm at 2 bars) (Figs 5-10a to 5-10h).

Fig 5-10 a Special alveolar model using the Willi Geller technique for fabricating alumina copings.

Fig 5-10 b Alumina copings after sintering in the ceramic furnace.

Fig 5-10 c Very fragile alumina copings after mechanical processing and fitting on the removable dies.

Fig 5-10 d Alumina copings being infiltrated with lanthanum aluminosilicate glass.

Fig 5-10 e, f Copings on the removable dies after the excess glass has been removed, ready to be sent to the dental office for the try-in step.

Fig 5-10 g Applying the liner powder from the VM7 kit (Vita) before layering the other ceramic powders.

Fig 5-10 h Restoring the crown morphology by layering the dentin powders. (Ceramist Csilla Szeredai.)

After the try-in of the alumina coping in the patient’s mouth, the ceramist begins the layering of an esthetic ceramic over the alumina core. This is done in a way that is very similar to the metal-ceramic technique, until the restoration of the morphology and the chromatic effects have been achieved. Generally, the dental technician starts with an opaque dentin layer that sketches the morphology, then proceeds with a translucent dentin layer, which finalizes the morphology. All are layered to an oversized morphology, as ceramics will shrink in the furnace.

Fig 5-10 i View of the surface micro-geography of the InCeram crowns.

Fig 5-10 j–l The final view of the crowns on the model. As alumina cannot be etched, it is necessary to treat the internal surface of the crown in the laboratory by sandblasting, and in the dental office by applying a ceramic primer. (Ceramist Csilla Szeredai.)

Sintering the ceramic after each individual layer is done in the conventional metal-ceramic furnace, which means there is no need for an extra investment for the dental laboratory (sintering is done at around 900°C to 930°C). As a veneering ceramic, Vita VM 7 (Vita) can be used (Figs 5-10i and 5-10j). 5.2.2.4 CAD/CAM systems for milling prefabricated ceramic blocks Digital technology has become increasingly important in dentistry today, for many reasons: the high production cost involved in the so-called “hand-made ceramics”; the human error factor; the need for a third-party dental laboratory; the continuous improvement of scanning and milling machines that make up the new CAD/CAM systems; and new performance software that allows the manufacturing, at an “industrial” scale, of hundreds of restorations per week, each with a perfect marginal fit and a high reproducibility, uninfluenced by the individual talent, or lack thereof, of the dental technician. There are hundreds of CAD/CAM systems available on the dental materials market today, with most of them having four basic components: 1. An image-acquisition unit. 2. Software that will make the restoration design on a virtual model. 3. A milling device that will produce the restoration from ceramic blocks; in the office for the CEREC 3 chairside systems (Sirona), or in the dental laboratory for the CEREC inLab systems (Sirona). 4. A communication system between the scanner and the milling device.

The acquisition systems may scan either in the dental office, whereby the prepared teeth are scanned directly in the patient’s mouth using an intraoral scanner (3M True Definition, E4D PlanScan, CEREC Omnicam), or in the dental laboratory, where in most cases a special plaster model made after a conventional dental impression will be scanned. In a few cases, the impression sent from the office is scanned (CEREC InEox X5, Dentsply Cercon eye).9

Fig 5-11 a–c One of the design steps in making a zirconia bridge using the Dental Wings Software. (CAD designer Asztalos Istvan.)

From the scans, specialized software will generate a 3D virtual model, on which the final restoration will be designed – again, either in the office or in the dental laboratory. Examples of currently available in-office systems are CEREC chairside system (Sirona) and Planmeca PlanScan (powered by E4D Technologies). The design is achieved by the dentist or another trained staff member who is guided step-by-step through the design process by the userfriendly software until the final ceramic restoration is achieved. Two of the laboratory systems used today are CEREC inLab and E4D PlanCAD Premium (Figs 5-11a to 5-11c). Following the design, the milling of the restoration occurs, which can be produced in the office with smaller milling units, or in the dental laboratory, using milling machines with several milling axes. In most cases today, the restoration is milled out of a pre-sintered zirconium dioxide block, which still requires a sintering phase after milling, so it will shrink a bit more. The end result is an infrastructure perfectly matching the master model, perfectly fitted at the margins. The zirconia framework can be milled in several ways to the final size of the restoration (also known as the full-contour zirconia crowns). It can also be milled to an undersize coping (ie, to a smaller dimension than that of the final restoration), thus leaving adequate space for the veneering material – generally a glass-ceramic with a crystalline phase (e.max, ZirPress, Ivoclar; Vita VM 9 or Vita PM 9, Vita). A combination of both of these techniques can also be used, so that the lingual surface is made in full-contour zirconia, while the labial/buccal sides are undercontoured, leaving space for the esthetic layering or pressing of a glass-ceramic. The CAD/CAM technology is often referred to as being synonymous with zirconia, but this is a misinterpretation, generated by the fact that zirconium dioxide cannot be processed through

conventional technologies in the dental laboratory; thus its applications in dentistry appeared only when the CAD/CAM systems emerged, and hence the incorrect supposition that these computerized systems all mill zirconium dioxide.9 Zirconia is an imprecise and incorrect name. The material used in dentistry is, in fact, a zirconium oxide – more specifically, zirconium silicate (SiZrO4). It is partially stabilized with yttrium oxide and compressed in the ceramic blocks that are used in the CAD/CAM machines. Its impressive resistance to flexion (900 to 1,100 MPa) is an important characteristic, as is its resistance to fracture (8 to 10 MPa), which makes it twice as resistant as the alumina copings, and 10 times more resistant than pressed ceramic9,24 (Figs 5-12a to 5-12f).

Fig 5-12 a The software allows us to fully contour the tooth morphology, especially in the posterior teeth, or reduce it to provide space for the ceramic layering, especially in the anterior area, for esthetic reasons.

Fig 5-12 b The final view of the full-contour zirconia crown on tooth 26.

Fig 5-12 c, d Layering technique of the dentin-ceramic powders (Vita VM 9) on the reduced zirconia framework.

Fig 5-12 e The final view of the anterior bridge.

Fig 5-12 f Checking the all-ceramic restorations using silver or gold powder.

Zirconium dioxide is currently used for many clinical procedures, eg inlays, onlays, veneers, crowns, highly esthetic restorations in extended edentulous spaces (either on teeth or implants), zirconia implant abutments, and frameworks for fixed or removable dentures in complex prosthetic cases. Two problems limited the use of zirconia in all types of restorations in the past. The first problem was the opaqueness and increased reflection of the zirconium dioxide copings. This meant that it could not be used in a single central incisor restoration. The problem was partially solved by infiltrating the pre-sintered copings to obtain a framework that was no longer white-opaque. The second problem was failures from chipping, or delamination of the veneering ceramic from the zirconia framework. This was due to the huge differences in the thermal diffusion speed of the two ceramic materials: zirconia heats and cools 10 to 20 times slower than the veneering ceramic. The problem occurs during the cooling process after sintering, as the veneering material cools faster and becomes rigid more quickly than the zirconia framework. This generates tension forces at the interface, and produces cohesive fractures between the two different layers. Full-contour zirconia crowns were specifically developed in an attempt to eliminate the frequent chipping of the VM23 (Figs 5-13a to 5-13f).

Fig 5-13 a The zirconia bridge using a full-contour zirconia crown on the molar and a reduced contour framework on the canine and the pontic, in order to be overpressed with e.max Zr Press ceramic.

Fig 5-13 b Applying the Zr liner on the zirconia framework before waxing; this provides a better bonding between the zirconia framework and the veneering-pressed glass-ceramic.

Fig 5-13 c, d The combined zirconia framework and wax pattern ready for investing.

Fig 5-13 e Investing the zirconia and the wax pattern for the overpress technique.

Fig 5-13 f The final view of the maxillary bridge after pressing, staining and glazing the overpressed e.max Zr Press, and polishing of the full-contour zirconia crown.

Which materials can be processed by the CAD/CAM technique? Most ceramics can be milled with CAD/CAM systems, including the three categories of

ceramic discussed below (see the classification according to microstructure by Giordano and McLaren):8 1. Category 2 – glass-ceramics enriched with lithium disilicate: used for conservative restorations – inlays, onlays, single crowns, anterior and posterior bridges, and veneers. There are two major companies producing these ceramic blocks for CAD/CAM: Vita (Vitablocs Mark II and Esthetic Line) and Ivoclar Vivadent (ProCAD and IPS e.max CAD). Both types can be processed exclusively with the CEREC inLab system (Sirona).26 2. Category 3 – crystalline-based systems: the ceramic blocks contain alumina or alumina and magnesium. They are milled only in the CEREC inLab system and then infiltrated with lanthanum aluminosilicate glass, using a similar technique to the InCeram system. Those based on alumina are ideal for crowns on the anterior teeth because the final product has a better translucency. They have also demonstrated excellent results in posterior crowns, and even in three-unit bridges in the anterior area.25,27 3. Category 4 – polycrystalline solids (zirconium dioxide): there are several systems, all of which can be placed in one of the following three categories: I. CAD/CAM systems that mill the restoration to the final contour from a completely sintered zirconia block (it does not require subsequent sintering). This is currently very expensive and also generates high temperatures during milling. Furthermore, it has a longer milling time due to the hardness of the ceramic block. These systems will be continuously improved in time as more research is undertaken in this field. II. The Procera system (Nobel Biocare) uses an oversized model on which alumina or zirconia copings are produced. The milled ceramic is sintered and shrinks to fit onto the original true-size model. This system is used to produce zirconia individualized abutments in the dental laboratory for Branemark implants. III. The third system is the most widely used in CAD/CAM dentistry today. It mills an oversized infrastructure from a pre-sintered zirconia ceramic block, which is sintered again to contract. The result is either a coping for a future crown, or an undersized framework for bridges, which are fitted onto the master model. Examples of this technology are inLab (CEREC), YZ Vitablocs (Vita), Zir. CAD (Ivoclar Vivadent), Lava (3M ESPE), Cercon (Degudent), and Everest (KaVo). Nowadays, CAD/CAM devices can also mill other materials besides ceramic (pre-sintered or sintered zirconia, pre-sintered alumina, glass-ceramic), such as:

• Metal frameworks made from Cr-Co, Ti alloys and, more recently, even gold alloys. • Wax that will be subsequently invested and cast in an alloy, or for pressing or overpressing onto the framework. • Resins that can be tried in the patient’s mouth for removable partial dentures. • Master models, which instead of gypsum are made of special resins, or through 3D printing. • Surgical guides in implantology, in combination with CBCT or CT, with the help of integrated software. • Full dentures or removable orthodontic appliances, as well as epithesis in complex craniofacial reconstructions. • Customized implant abutments in complex cases, from various types of materials: Ti, zirconium dioxide, e.max CAD, or resins that are then pressed or invested. • Composite that can be veneered with light-cured laboratory composites (Vita CAD Temp, BioHPP). In dentistry, the history of the CAD/CAM systems has been synonymous with the CEREC system (Chairside Economical Restoration of Esthetic Ceramics) (Sirona) for over 20 years. From 1960, CAD technology was used in various fields (industrial, design, construction), but the idea to introduce automated manufacturing of prosthetic works first came from Duret in 1971. In 1980, Prof Mörmann from Zurich University, together with his engineer friend Brandestini, conceptualized and produced the first CAD/CAM system for dentistry – the first CEREC machine.28,29 The CEREC system mills a restoration from a pre-sintered ceramic block to obtain a monochrome crown, which is individualized by external painting. Initially, the marginal fit of these CAD/CAM crowns was poorer than the fit of conventionally fabricated crowns. By perfecting the image-acquisition systems, as well as the scanning and milling machines, the marginal fit has now improved considerably. Thus, the newer generations (those produced after 2000) reached a scanning camera resolution of 25 µm and the milling unit (MCXL), 30 µm. Improvements to the CEREC system followed, generating several generations of such systems: CEREC 1 (1987), CEREC 2 (1994), and CEREC 3 (2000). In 2003, the 3D software version appeared, which allows the models to be viewed in 3D. In 2005, the in-office CEREC system was the only existing office system. In 2008, the MCXL milling unit could produce a partial crown in 3 to 4 minutes, and a full-contour crown in 6 minutes. The CEREC

Acquisition Center, powered by Omnicam, appeared in 2013.30,31 Being over 20 years old, CEREC is one of the few systems that has been studied in the longer term. Posselt reported a 95.5% success rate at 9 years for 2,300 CEREC inlays and onlays; Reiss reported an 84.4% success rate at 18 years for 1,100 inlays and onlays; and Wiedhahn reported a 94% success rate for veneers at 9.5 years.32–34 Other current CAD/CAM systems include Cercon (Degudent), Lava (3M ESPE), Everest (KaVo), E4D (E4D Technologies), and Cadent iTero (Align Technologies). 5.2.3 Conclusion Dentists today have numerous ceramic systems available to them, with as many technological laboratory procedures and various types of fixed restorations that give their patients the best esthetic results. From the minimally invasive ceramic restorations (made of feldspar ceramic with a very low flexural strength but with a 94% survival rate at 10 years), to indirect restorations made of glass-ceramic or alumina-based ceramic (which can be used for many purposes, from mini-veneers/laminate veneers to short-span bridges in the lateral area), to the most complex restorations made of high-resistance ceramic, or computer-assisted milling procedures on teeth or implants. The use of all-ceramic systems in dentistry has continually increased over the past 20 years. Thus, in the USA alone, 600,000 restorations were made in 2004 using only the CAD/CAM technique, and in 2011, over 6 million such ceramic restorations were undertaken. This trend will continue in the future.35,36 However, dentists should be aware that not all systems are the same; they differ significantly according to their physical properties (mechanical and optical), the final esthetic result, and their long-term survival rate. The success of a all-ceramic restoration depends on the clinical rationale in choosing a treatment plan, the patient-related factors, the correct choice of the proper materials relating to the clinical case, whether there is appropriate technology in the dental laboratory, and the dentist’s ability to perform the best possible preparation, impression, and adhesive cementation, which determines the long-term success of this type of restoration. It is to this end that the authors have detailed some properties of various ceramics and explained some of the laboratory procedures fundamental to the ceramic systems that are currently most widely used. Although the information in this chapter is not exhaustive, we hope that it will be helpful to dentists who are using, or would like to use, ceramics for restorations in their esthetic dentistry practice.

REFERENCES 1. Griggs JA. Recent advances in materials for all-ceramic restorations. Dent Clin N Am 2007;51:713–727. 2. Donovan T. Factors essential for successful all-ceramic restorations. J Am Dent Assoc 2008;139;14S–18S. 3. Borzea D. Ceramica in Stomatologie. Cluj-Napoca: Dacia, 2000. 4. Rosenstiel SF. Land MF, Fujimoto J. Contemporary Fixed Prosthodontics, ed 4. St Louis: Mosby, 2006. 5. Nicola C. Materiale dentare – consideratii clinice si tehnologie. Cluj-Napoca: Casa Carţii de Ştiinţă, 2009. 6. McLaren EA, Cao PT. Ceramics in dentistry Part I: Classes of materials. Inside Dentistry 2009:94–104. 7. Craig RG, Powers JM. Restorative Dental Materials, ed 11. St Louis: Mosby, 2002. 8. Giordano R, McLaren EA. Ceramics overview: Classification by microstructure and processing methods. Compend Contin Educ Dent 2010;31:682–684, 686, 668. 9. McLaren EA, Giordano RA. Zirconia-based ceramics: Material properties, esthetics and layering techniques of a new veneering porcelain, VM 9. Quintessence Dent Technol 2005;28:99–111. 10. McLaren EA, White SN. Glass infiltrated zirconia/alumina–based ceramic for crowns and fixed partial dentures. Clinical and laboratory guidelines. Quintessence Dent Technol 2000;23:7–26. 11. Sailer I, Feher A, Filser F, Gauckler LJ, Luthy H, Hammerle CH. Five-year clinical results of zirconia frameworks for posterior fixed partial dentures. Int J Prosthodont 2007;20:383–388. 12. Christensen RP, Eriksson KA, Ploeger BJ. Clinical performance of PFM, zirconia and alumina three-unit posterior bridge (abstract). [The IADR 86th General Session and Exhibition, 1–5 July 2008, Toronto, Ontario]. http://iadr.confex.com/iadr/2008Toronto/techprogram/abstract_105962.htm. Accessed July 2014. 13. Magne P, Belser U. Bonded Porcelain Restorations in the Anterior Dentition: A Biomimetic Approach. Chicago: Quintessence, 2002. 14. Lasserre JF, Laborde G, Koubi SA, et al. Restaurations céramiques antérieures (2): Préparations partielles et adhésion. Réalités Cliniques 2010;21:183–195. 15. Gürel G. The Art and Science of Porcelain Laminate Veneers. Chicago: Quintessence, 2003. 16. Höland W, Apel E, van’t Hoen C, Rheinberger V. Studies of crystal phase formations in high-strength lithium disilicate glass-ceramics. J Non-Cryst Solids 2006;352:4041–4050. 17. Culp L. McLaren EA. Lithium disilicate: The restorative material of multiple options. Compend Contin Educ Dent 2010;31(9):716–725. 18. Ivoclar Vivadent. IPS e.max Lithium Disilicate: the Future of All-Ceramic Dentistry – Material Science Practical Applications. Key to Success. Amherst, NY: Ivoclar-Vivadent 2009;1-15. 19. Tysowsky G. The science behind lithium disilicate: Today’s surprisingly versatile, esthetic and durable metalfree alternative. Oral Health J 2009:93–97. 20. Aboushelib MN. Long-term fatigue behavior of zirconia based dental ceramics. Dent Mater 2010;3:2975– 2985. 21. Scotti R, Catapano S, D’Elia A. A clinical evaluation of InCeram crowns. Int J Prosthodont 1995;8:320–323. 22. McLaren EA, White SN. Survival of In-Ceram crowns in a private practice: A prospective clinical trial. J Prosthet Dent 2000;83:216–222. 23. Anusavice KJ. Standardizing failure, success, and survival decisions in clinical studies of ceramic and metalceramic fixed dental prostheses. Dent Mater 2012;28:102–111.

24. White SN, Miklus VG, McLaren EA. Flexural strength of a layered zirconia and porcelain dental all ceramic system. J Prosthet Dent 2005;4:125–131. 25. Guazzato M, Albakry M, Ringer SP, Swain MV. Strength, fracture toughness and microstructure of a selection of all-ceramic materials. Part I. Pressable and alumina glass-infiltrated ceramics. Dent Mater 2004;20:441–448. 26. Mörmann WH. State of the Art of CAD/CAM Restorations, 20 Years of CEREC. Berlin: Quintessence, 2006. 27. Denry I, Kelly JR. State of the art of zirconia for dental applications. Dent Mater 2008;24:299–307. 28. Santulli GA. NPDS Fixed Prosthodontics Syllabus. 2003;170-181. 29. Al-Wahadni A, al-Dwairi ZN, Rashid S. History, development and clinical success of porcelain inlays. J Ir Dent Assoc 2000;46:49–54. 30. Fasbinder DJ, Multi-center trial: Margin fit and internal adaptation of CEREC crowns. In: Mörmann W. The evolution of CEREC system. J Am Dent Assoc 2006;137:5–13. 31. Kerschbaum T. A comparison of the longevity and cost-effectiveness of three inlay-types. In: Mörmann WH (ed). State of the Art of CAD/CAM Restorations, 20 Years of CEREC. Berlin: Quintessence, 2006:73–82. 32. Posselt A, Kerschbaum T. Longevity of 2328 chairside CEREC inlays and onlays. Int J Comput Dent 2003;6:231–248. 33. Reiss B, Eighteen-year clinical study in a dental practice. In: Mörmann WH (ed). State of the Art of CAD/CAM Restorations, 20 Years of CEREC. Berlin: Quintessence, 2006:57–64. 34. Wiedhahn K. CEREC veneers: Esthetics and longevity. In: Mörmann WH (ed). State of the Art of CAD/CAM Restorations, 20 Years of CEREC. Berlin: Quintessence, 2006:101–112. 35. McLaren EA, Whiteman YY. Ceramics: Rationale for material selection. Inside Dentistry 2012;238–352. 36. Millenium Research Group. US Market Report for Crowns and Bridges 2011.

FLORIN LĂZĂRESCU

Chapter VI ULTRACONSERVATIVE DENTISTRY

6.1 MODERN ESTHETIC DENTISTRY Systematic respect for the original tissue, a concept that can be applied to all aspects of dental medicine, is the foundation of ultraconservative dentistry; the common denominator is preservation or minimal removal of dental tissue. Advanced specialization in various fields of dental medicine (for instance, prosthodontics, periodontics, orthodontics, endodontics, pediatric dentistry, dental implantology, etc) may benefit the patient who enjoys high-quality healthcare. The drawbacks may be a sometimes narrow approach to the case, and lack of perspective in the absence of comprehensive treatment planning, which should take into account the overall health of the patient and the ultraconservative character of the restoration, as well as issues related to pain, mastication, and esthetics. Patients’ expectations of the healthcare system are completely different today to what they were a few years ago, and are constantly changing due to the ease of access to online information, the growing awareness of general health (regular medical checkups, healthy diets, balanced lifestyles), and patients’ wishes for dental restorations that will last – and have a warranty for – a lifetime. Often, a dentist has to deal with patients who ask for a second or third opinion before they agree on a treatment plan, patients with health issues associated with tooth disorders (temporomandibular joint [TMJ] or muscle disorders, bad habits, etc), or patients with psychological disorders. In many such cases, a highly subjective approach should take priority over objective clinical and paraclinical examinations.1 Taking all the aforementioned aspects into consideration – and considering that people often come to the dentist chiefly to improve their looks – it is extremely important for dentists whose practice is primarily focused on cosmetic dentistry to have a broad and comprehensive overall perspective of the patient’s clinical condition, as well as a multidisciplinary approach to treatment planning. The ultimate purpose is to achieve an ultraconservative and esthetic functional restoration that satisfies the patient, has a long lifespan, and is in agreement with the principles of modern dentistry. Nowadays, patients are guided by the ultraconservative principle and are reluctant to agree to a treatment plan that does not take this principle into consideration. 6.1.1 Magnification, illumination, and isolation in ultraconservative dentistry

Visibility within the oral cavity is often limited because the dentist’s vision can be restricted by various structures. It can therefore be difficult to access a tight space. In order to gain the best access and visibility inside the oral cavity, the dentist often assumes unnatural and stressful body positions, which in time lead to posture-related musculoskeletal problems and even impaired mobility and working capacity. The lesser the amount of tooth structure removed during preparation and the smaller the operative site, the greater the amount of equipment needed to assist the dentist in current practice. Dental magnification loupes and microscopes are really helpful in this respect. The most significant advantages are the following:2 • Visibility is improved. • Illumination is improved. • Isolation is controlled. • Preparation is controlled. 6.1.1.1 Magnification Dental loupes and microscopes improve ergonomics and ensure that the dentist maintains correct posture, affording more productive and less stressful work sessions, thereby alleviating muscle pain and improving comfort at work (Figs 6-1a and 6-1b). At the same time, esthetic preparations require precision down to the micron level. One can be certain that a barely visible effect magnified to 2.5 with loupes, or even higher with a microscope, cannot be detected by the human eye.2 While loupes and microscopes were originally used strictly in cosmetic dentistry, they have become indispensable tools in endodontics and periodontics (Figs 6-2a to 6-2d).

Fig 6-1 a Correct body posture of a dental practitioner using loupes.

Fig 6-1 b Correct body posture of a dental practitioner using a microscope.

Whereas loupes were employed by elderly dental practitioners in the past, they are now being used as early as dental school. A survey of 332 dentistry students, 50% of whom used loupes, recorded the number of preparations per time unit and the time required for one preparation. The investigated preparations on dental phantoms comprised class I, II, III, and V

cavities. The results were statistically significant in favor of the students who used loupes, both for the number of prepared teeth per time unit and for the cavity preparation speed per procedure for all types of cavities. The study also revealed a high degree of student acceptance of the use of magnification, because in this way they could better self-evaluate their performance.3

Fig 6-2 a 1:1 ratio visualization of preparation.

Fig 6-2 b 2.5:1 ratio visualization of preparation with dental loupes.

Fig 6-2 c OPMI pico – ZEISS surgical microscope.

Fig 6-2 d 21:1 ratio visualization of preparation with the optical microscope. (Photo courtesy of Dr Monica Voiculeanu.)

Fig 6-3 a Dental loupes with LED headlight.

Fig 6-3 b Visualization of operative site by means of an external LED source.

Hand in hand with the technological development of dental materials (porcelain, bonding agents, composite resins, and cements) that has made ultraconservative dentistry possible, selfevaluation due to magnification has significantly enhanced performance and the quality of preparations, which has consequently led to better patient satisfaction. 6.1.1.2 Illumination It is now inconceivable for a dentist to acquire dental equipment without a fiber optic illumination system to light the operating site. However, sometimes a wider visibility area is required. The development of LED technology, and its association with dental loupes by direct attachment to glasses without special support systems, has led to it becoming extremely popular in dental practice (Figs 6-3a and 6-3b). 6.1.1.3 Isolation During dental procedures, teeth or soft tissues are sometimes not visible enough. Apart from the presence of saliva, the tongue or cheeks may obstruct the operative field. The four-handed technique is quite useful when dealing with this problem. Yet again, technology has provided helpful tools: for instance, the Isolite isolating system, which consists of a single-use flexible mouthpiece that can be inserted into the oral cavity and is bitten down on by the patient. The system allows the patient to feel relatively comfortable, even during a lengthy treatment. The operative field is illuminated by an LED source. Aspiration is possible both in the oral and facial sides of the field (Fig 6-4).2

Fig 6-4 Isolite system. (Courtesy of Isolite Systems - http://www.isolitesystems.com.)

Fig 6-5 Rubber dam isolation of the operative field for cementation of eight porcelain veneers.

Fig 6-6 a Initial clinical situation.

Fig 6-6 b Change in shape and position by using six porcelain laminate veneers applied from 13 to 23.

The rubber dam is a must for bonding, as it is the only method of isolating teeth that is comfortable for the patient and has a predictable result over a period of time (Fig 6-5). 6.1.2 Preparation in ultraconservative dentistry In the eyes of both the dentist and the patient, porcelain laminate veneers stand for ultraconservative or minimally invasive dentistry. Dentists and patients alike choose veneers over traditional crowns because they enable a more esthetic restorative procedure. They are also minimally invasive and have a lower risk of subsequent complications. However, if proper tooth preparation is not followed, or treatment planning is incorrect, the restoration may fail. Porcelain laminate veneers can effect changes in the color, shape, and position of the teeth (Figs 6-6a and 6-6b). In order to avoid any risk, tooth preparation should always be limited to the enamel. On average, considering the initial tooth color and the type of porcelain, dental preparation should go no deeper than 0.4 to 0.8 mm.1 Taking into account the progress achieved in increasing the strength of bonding agents and porcelain, tooth preparation for all-ceramic crowns may be approached as a preparation for an extended veneer. It requires a minimally invasive preparation of all sides of the tooth without strictly following the rules of minimal tooth reduction – such as for porcelain fused to metal (PFM) crowns, for instance. Preservation of the dental structure and the enamel is paramount for this type of preparation.4 Sometimes in clinical situations, the preparation might extend to limited areas of the dentin, chiefly to the cementoenamel junction (CEJ), where the enamel is less thick (Figs 6-7a and 67b). Even in the case of the latest adhesives that create a solid and stable bond with the tooth

enamel and dentin (in contrast with the first generations of bonding agents that adhered only to the enamel), the adhesion to the enamel is much stronger than it is to the dentin. Therefore, it is recommended that the preparation be limited to the enamel.

Fig 6-7 a Dental preparation limited to the enamel.

Fig 6-7 b Dentin exposure at the cervical part of 13, irrespective of the minimally invasive tooth preparation.

Fig 6-8 a,b Orthodontic alignment in order to permit minimally invasive procedures for tooth preparation.

Fig 6-8 c,d Result after orthodontic alignment.

Fig 6-8 e Maxillary incisors are not visible when the lips are at rest.

Fig 6-8 f Provisional restorations in the oral cavity before preparation (mock-up) according to the wax-up prepared in the dental technical laboratory.

Fig 6-8 g Maxillary incisors are visible with the mock-up.

Fig 6-8 h The mock-up allows esthetic assessment prior to teeth preparation.

Before ultraconservative preparation takes place, preliminary orthodontic tooth realignment is often required. Only when this treatment has been completed can one proceed with dental preparation for veneers or crowns; consequently, teamwork with the orthodontist is very important (Figs 6-8a to 6-8d). In order to remain faithful to minimally invasive procedures, the dentist needs to communicate clearly with the patient to make him/her aware of the treatment methods (wax-up, mock-up, and digital smile design). The dental preparation should only begin once the patient has a clear vision of the end result.

Fig 6-8 i Guided preparation with the mock-up restoration.

Fig 6-8 j Teeth prepared before impression, with retraction cords. The minimally invasive preparations limited to enamel only are evident.

Fig 6-8 k Porcelain veneers prior to bonding.

Fig 6-8 l–s The final result shows functional, biological, and esthetic rehabilitation.

A good means to communicate the treatment plan to the patient may be a plain impression of the initial situation. This is sent to the dental laboratory to act as a manufacturing restoration template (known as a wax-up), which strictly follows the dentist’s directions. The template can be built in the oral cavity (by imprinting the wax-up template and creating provisional restorations into the mouth – a mock-up), which offers an even more tangible picture of the final outcome of the restoration process. Some authors describe techniques in which the dental preparation is guided by the provisional restoration (Gürel technique),1 so that the preparation is even more conservative (see Chapter IV) (Figs 6-8i to 6-8s). The mock-up with provisional restorations enables an ultraconservative preparation, even in the case of slight inconsistencies or position changes. At the same time, provisional restorations play a most significant part in the esthetic, phonetic, and functional assessment, even before any tooth preparation.4 Placing restorative margins has always been a challenge for the dentist. The placement of the restorative margins supragingivally has obvious advantages: better hygiene, better visual control of the procedures, better impression control, easier to bond, and, implicitly, easier for the technician when manufacturing the model and fabricating the restoration. On the other hand, there is also the esthetic aspect and the patient’s preferences, especially when it comes to tooth pigmentation. The cervical margin of the tooth deserves special attention, and it is recommended that it be placed supragingivally (Figs 6-9a to 6-9f). Subgingival margin preparation may cause gum irritation and retraction due to the contact with the thin layer of cement at the tooth-veneer interface. All margins of the preparation must be rounded to avoid stress in the porcelain. In the case of porcelain veneers, special attention must be given to the preparation of the proximal margins, and the placement of the facial-proximal margins of the veneers that are visible and can cause esthetic problems if inaccurately prepared (Fig 6-10).10

Fig 6-9 a Unesthetic joined-together crowns on 22 to 24.

Fig 6-9 b Final clinical situation.

Fig 6-9 c The patient’s smile is unesthetic.

Fig 6-9 d Postoperative view of the patient’s smile after 3 years.

Fig 6-9 e Supragingival margin. preparation.

Fig 6-9 f Postoperative clinical situation after 3 years.

There are two circumstances in which the margins of the veneer may be placed subgingivally, ie, in the dental preparation of teeth with gaps, and where teeth have an abnormal color. In the former circumstance, subgingival preparation is recommended because the emergence profile and interdental papilla must be remodeled; in the latter, it is recommended that abnormal tooth color be camouflaged. The more obvious the color changes, the deeper the preparation (Figs 6-11a to 6-11c).5 Special attention should be given to bonding esthetic restorations. Due to ultraconservative preparation, dental restorations are very thin, therefore both the abutment and the luting resin are likely to be seen through the restoration. Glycerin try-in pastes are recommended as they can highlight potential chromatic changes in the final restoration before bonding. Several studies reveal that plaque accumulation is most often present on feldspathic porcelain and, after that, on lithium disilicate ceramics, although significantly less. The lowest degree of plaque accumulation is found on oxide crystalline ceramics (zirconium dioxide).6

The tooth-restoration interface is most prone to plaque accumulation, which is another reason why supragingival placement of the margin preparation is recommended.

Fig 6-10 Subgingival placement of the preparation margin on 12 and 13 with the presence of gum irritation areas.

Fig 6-11 a Initial clinical situation with color changes on the cervical area of 22.

Fig 6-11 b Subgingival margin preparation to camouflage coloration.

Fig 6-11 c Final clinical situation.

6.1.3 The importance of dental materials in modern esthetic dentistry Esthetic rehabilitation depends on the materials used in dental restoration. Dental amalgam and glass ionomers are excluded from the very beginning if esthetics is important. To follow ultraconservative principles closely, one must eliminate PFM restorations, whose multilayered structure (metal, opaque, and ceramic mass) requires a more invasive preparation than allceramic crowns. Besides the invasive preparation, the esthetics of PFM restorations is rather poor due to metal opacity. The only materials that can be used in minimally invasive esthetic preparations are composite resins (using a direct or indirect technique) and ceramic materials. 6.1.3.1 Composite resins Even though composite resins are not the first choice for veneers owing to their characteristics (bacterial plaque accumulation, wear out, chromatic changes in time), they still play a significant part in direct esthetic restorations. At the same time, they are important in circumstances in which the advantages of porcelain restoration are overshadowed by the need to remove too much healthy tissue. For instance, composite resins are a solution in the case of non-invasive restorations of teeth with damaged periodontium, which usually have clinically too-long crowns, widened interdental space, and loss of interdental papillae, or in cases in which prosthetic solutions to unesthetic interdental spaces would be considered invasive. It can be difficult to diagnose very small dental cavities with traditional exploration techniques (histological studies show a 25% diagnostic accuracy ratio of cavities located under the occlusal surface).7 Bite-wing radiographs are useful for identifying such types of tooth decay. Some studies reveal that only a third of incipient cavities are diagnosed visually, whereas two-thirds are found by radiographics investigations.8 Undoubtedly, the association of

the two methods of exploration may supply more accurate information. Auxiliary techniques, such as electrical conductance measurements, laser cavity detection systems (such as the DIAGNOdent manufactured by KaVo), and fiber optic transillumination (DIAGNOcam, KaVo), may be quite useful, mainly for monitoring a suspected cavity (Figs 6-12a and 6-12b).9 A potential complication may be the constant and too aggressive use of fluoride in communities provided with systemic fluoride administration. Studies show that excessive fluoride ingestion may lead to undiagnosed hidden cavities. Fluoride strengthens tooth enamel, making the tooth surface impenetrable and difficult to explore, but at the same time masking the decay immediately under the tooth surface and along the CEJ.10

Fig 6-12 a DIAGNOdent cavity detection system.

Fig 6-12 b DIAGNOcam cavity detection system. (Courtesy of KaVo Dental.)

Ultraconservative procedures in the treatment of these types of cavities involve remodeling grooves for ease of access and visibility, complete removal of decayed tissue, and the use of flowable composite resins to ensure that they fill the whole, often irregular, cavity, which is

not possible with traditional normal composite materials. To maintain ultraconservative preparation procedures, new methods of treatment should be taken into consideration, for example, sonic and ultrasonic procedures, air abrasion cavity preparation systems, and ozone therapy. 6.1.3.2 Porcelain Porcelain is well known for its likeness to dental enamel, being able to replicate faithfully the colors and texture of the natural tooth. It allows the dentist to clinically restore patients’ teeth both to function like and to look like their natural teeth.11 Porcelain restorations can be bonded to dental structures to form a single unit with the tooth, which increases the resistance of the final restoration. Technological advancement in the production of porcelain (strength, biocompatibility, esthetics) and of resin cements that enable the adhesion of porcelain to tooth structures has revolutionized traditional prosthetic techniques. The latter has demanded compliance with clear-cut principles in order to achieve long-lasting esthetic results, whereas the leading goal of minimally invasive, ultraconservative dentistry is the preservation of dental and periodontal structures. Zirconium dioxide, which does not allow bonding to tooth structures, has excellent strength and esthetic qualities, presenting a better choice than metallic structures (Fig 6-13). Modern technologies (the presence of computer-aided design/computer-aided manufacturing [CAD/CAM] systems in dental practices) allow long-lasting esthetic therapeutic solutions with a good prognosis, due to the accuracy of the marginal fit, restoration bonding, and use of ceramic materials in various types of preparations (inlay, onlay, veneers, crowns, bridges – see Chapter XII). Another reason porcelain restorations are accepted by patients may be the fact that they can be manufactured quickly, in contrast to previous procedures that involved the dental laboratory. Whereas the role of cementing agents used in the past (zinc oxyphosphate) was simply to fill the space between crown and tooth (augmenting mechanic retention by friction), modern bonding resins are based on chemical and physical fusion with both the tooth structure and the porcelain restoration, resulting in one unit made up of the three constitent elements.11 Ultraconservative techniques also take into account the periodontium, preventing its damage during preparation, impression, and bonding procedures. Ultraconservative dentistry also protects soft tissues, attempts to remove as little of the

healthy tooth structure as possible, is highly esthetic, and uses the strength of the restoration materials to make the natural teeth stronger.11

Fig 6-13 Very thin porcelain veneer.

6.1.4 Postoperative clinical examination of preparations The patient must return 2 to 3 days post-cementation to check whether any bonding resin residue has been removed. Besides twice a day tooth brushing, the importance of auxiliary oral hygiene (dental floss, super floss, mouthwash) should be explained to the patient. The toothrestoration interface – the interproximal area for veneers – is the area most exposed to secondary cavities. Good oral hygiene in these high-risk areas is closely related to long-lasting restorations, and the patient should be made aware of this fact when given instructions on various techniques to maintain oral hygiene. At the same time, supragingival preparations must be performed whenever possible so that the patient is able to keep the margin area clean, with no plaque accumulation.

6.2 FUNCTION AND ESTHETICS When all the teeth are affected, increasing the vertical dimension of occlusion (VDO) is often the best solution with multiple restorations. In most cases, generalized wear is accompanied by VDO reduction; traditional treatment may turn extremely invasive as mechanical retention of the restorations is necessary. Traditional treatment consists of endodontic therapy, post and core restorations, and crown lengthening by surgically removing soft and bone tissue. VDO augmentation might be the best solution to avoid such invasive procedures. A lesser amount of hard tissue has to be removed by realignment to centric relation (CR) position as a result of VDO augmentation, verifying the position by using occlusal appliances that can be adjusted until the patient feels comfortable, and by applying provisional restorations before definitive restorations. By associating VDO augmentation with preparation, not of the teeth surface but of the provisional restorations used to test the new position, the preparation is certain to be kept minimally invasive. An attempt at partial rehabilitation – limited to the anterior teeth, for example – that consists of crown lengthening in order to achieve an adequate length ratio between incisors and gum by excessive extension of the ceramic restoration without tooth support and with no VDO augmentation that involves the posterior teeth will be doomed to fail due to extreme wear of the antagonists, ceramic chipping, or both (Figs 6-14a to 6-14h).11 If a one-tooth PFM restoration has three layers (metal, opaque, and ceramic), which would call for a thicker preparation, subsequent restorations requiring minimal preparation may be onlays or all-ceramic crowns.

Fig 6-14 a Initial clinical situation.

Fig 6-14 b Final clinical situation.

Fig 6-14 c–e (note: image 6-14e appears on the following page) Areas of marked attrition and wear where the pulp chamber is visible.

Fig 6-14 f Initial clinical situation in occlusion.

Fig 6-14 g The upper arch in the initial situation.

Fig 6-14 h By applying an anterior jig for 6 weeks, the CR is restored and a new VDO is tested.

Fig 6-14 i Pre-preparation clinical situation with mock-up restorations.

Fig 6-14 j and k The mock-up guided preparation of all maxillary and mandibular teeth, associated with VDO augmentation, enables the preservation of the minimally invasive character of the preparations.

Fig 6-14 l–o Preparation restricted to the tooth enamel guarantees a long-lasting restoration.

Fig 6-14 p and q Pre-cementation final preparations.

Fig 6-14 r and s Post-cementation occlusal views.

Fig 6-14 t Radiologic situation before prosthetic treatment (after orthodontic and implant treatment).

Fig 6-14 u Final radiologic situation maintaining tooth vitality.

Fig 6-14 v–y The final result is a complete functional, biological, and esthetic rehabilitation.

The key elements for such treatment to be successful in cases of total rehabilitation are:4 • VDO augmentation (the treatment plan must address at least one arch). • Minimally invasive occlusal preparations, no bigger than 0.8 to 1 mm, to preserve as much enamel as possible. Marginal preparations should be also minimally invasive in order to achieve the best possible bonding (Figs 6-14i to 6-14o). • Using lithium disilicate for posterior preparations to increase strength.

• Bonding of all restorations (Figs 6-14p to 6-14s). The VDO augmentation ratio is 1:3 between the oral and the facial area. A significant VDO augmentation in the facial area allows the patient to look much younger. At the same time, VDO augmentation in the oral area (even 1 mm), associated with the use of hard porcelain (eg, lithium disilicate), allows a minimally invasive tooth preparation, or even no preparation at all. The dentist’s aim should be to achieve completely non-invasive restorations and keep healthy dental structures untouched. The progress that has been made in the area of preparation techniques and restoration and bonding materials points in this direction and allows one to be hopeful that one day this goal will be achieved: no preparations at all, or ultraconservative ones when absolutely necessary (Figs 6-14t to 6-14y). It is sometimes hard to achieve this goal because patients wish to have immediate results and refuse interdisciplinary treatment that requires time. Even when the patient does not cooperate and one is compelled to make a compromise, it is always advisable to take a step back and think twice about whether the patient’s wish coincides with the medical rationale and the right intentions.

REFERENCES 1. Romano R. The Art of Treatment Planning. Chicago: Quintessence, 2010. 2. Freedman G. Contemporary Esthetic Dentistry. St Louis: Mosby, 2012. 3. Maggio MP, Villegas H, Blatz MB. The effect of magnification loupes on the performance of preclinical dental students. Quintessence Int 2011;42(1):45–54. 4. Fradeani M, Barducci G, Bacherini L, Brennan M. Esthetic rehabilitation of a severely worn dentition with minimally invasive prosthetic procedures. Int J Periodontics Restorative Dent 2012;32(2):135–147. 5. Cohen M. Interdisciplinary Treatment Planning. Chicago: Quintessence, 2008. 6. Bremer F, Grade S, Kohorst P, Stiesch M. In vivo biofilm formation on different dental ceramics. Quintessence Int 2011;42(7):565–574. 7. Lussi A. Comparison of different methods for the diagnosis of fissure caries without cavitation. Caries Res 1993;27(5):409–416. 8. Richardson PS, McIntyre IG. The difference between clinical and bitewing detection of approximal and occlusal caries in Royal Air Force recruits. Community Dent Health 1996;13(2):65–69. 9. Tam LE, McComb D. Diagnosis of occlusal caries: Part II. Recent diagnostic technologies. J Can Dent Assoc 2001;67(8):459–463. 10. Ellwood RP, O’Mullane DM. Dental enamel opacities in the groups with varying levels of fluoride in their drinking water. Caries Res 1995;29:137–142. 11. Freedman G. Contemporary Esthetic Dentistry. St Louis: Mosby, 2012:72–98.

CONSTANTIN VÂRLAN BOGDAN GALBINASU

Chapter VII ADHESIVE TECHNIQUES IN ESTHETIC DENTISTRY

7.1 BASIC ASPECTS 7.1.1 Introduction Nowadays, there is almost unanimous agreement that bonding agents and procedures are the greatest breakthrough in the entire history of restorative dentistry. They have played a crucial part in the contemporary implementation and advancement of the increasingly popular esthetic aspects related to this field. Adhesion to dental tissues, as well as to synthetic materials such as porcelain and polymer structures (resins), and even metal alloys, has revolutionized the principles and methods of current practice. A comprehensive understanding of the phenomena taking place at the bonding interface of adhesive restoration requires a good knowledge of surface physical processes, such as surface tension and energy, wettability, and capillarity, as well as of those related to rheology, such as viscosity, flow, and thixotropy.1,2 The practical applications of these are to be found in various characteristics of the materials, which have a varying impact on their clinical behavior. There are various mechanisms which, if understood, may allow us to make the best use of specific materials in different clinical situations for which they are required and for which they have been created. These include adhesion of bonding agents, dental structures, micro- or nanoinfiltration of gaps or small enamel fractures around the dental restoration, etc.2 Adhesive bonding is the attraction between two surfaces in very close contact due to intermolecular forces that act at a very small distance. The materials able to bond two surfaces are called adhesives, and the material on which the adhesive is applied is called the adherent or substrate. There are several types of adhesion, depending on the nature of the forces that keep two surfaces together:2 • Mechanical adhesion: present between rough surfaces due to mechanical friction. When the height of a roughness profile is at micron level (10-6 m), the physical process is called micromechanical adhesion and the respective roughness is called micromechanical retention. • Electrostatic adhesion: occurs due to the attraction between opposite electrical charges. • Dispersive adhesion: occurs due to bonds formed when the adhesive wets the substrate, resulting in a physicochemical adsorption. The intermolecular entanglement is the main force determining the adhesion: van der Waals forces (Keesom force, Debye force, London

dispersion force), hydrogen bonding. • Chemical adhesion: when the superficial atoms of two surfaces form ionic, covalent, or coordinate bonds.2,3 Mechanical, dispersive, and chemical adhesion are the foundation of bonding procedures in dentistry, leading to achievements impossible to reach with traditional techniques based only on geometric mechanical retention. They allow treatment in much more diverse clinical situations, with a better prognosis in time and, most obviously, with superior esthetic results.2,4 Mechanical interlocking also enables the adhesive to penetrate into the microscopic or submicroscopic irregularities of the adhered surface of a substrate. This type of bonding is known as micromechanical adhesion.3,5 The essential condition necessary in order to achieve a strong and durable interface bond is to have a permanent and as close as possible contact between the surfaces of the adhering bodies. In such cases, mechanical adhesion is accompanied by dispersive adhesion due to intermolecular attractions. The latter forces are efficient only if the distance is very small, ie, 1 to 2Å (1Å = 10-10 m). Consequently, when the conditions are right for the molecules of the adhesive to come into intimate contact with the molecules of the adherent at such a small distance, intermolecular forces of attraction emerge at once and determine the adsorption of the adhesive to the substrate, at the same time achieving its adhesion.2–4 7.1.2 Brief history The first attempt at tooth bonding was made by Hagger who, in 1949, developed an adhesive system based on glycerophosphoric acid dimethacrylate, which he used to seal the margin and “stick on” the cavity walls. It is associated with a self-curing acrylic resin for crown restorations. But the modern era of adhesive dentistry was initiated in 1955 by Buonocore, who was inspired by the methods used in the naval industry to improve the adhesion of paint and glaze to metal surfaces. He suggested that tooth enamel should be treated with phosphoric acid (at an initial concentration of 85%) in order to improve its bonding with the restorative resins.6,7 Acid etching became really useful a few years later, in 1962, when Bowen introduced the first effective resin-based dental composite called Bis-GMA. He was inspired by Knock and Glenn who, in 1951, suggested incorporating filling ceramic particles into the resins in current use at that time.8

In 1966, using the “Bowen-formula resin” (Bis-GMA) as a starting point, Newman and Sharpe developed a new composition with a much lower viscosity. They achieved this by eliminating the entire ceramic filling from the initial structure, thus creating the first dental adhesive. Owing to its high efficiency and the low risk of technical errors, the procedure of acid etching of tooth enamel to increase the bond strength with the composite resin has continued to be used, although it has been subject to some changes in principles or techniques, such as decreasing the phosphoric acid concentration from 85% to 30–40% and the etching time from 40–60 to 15–20 seconds, as well as the use of etching products in the form of gel, etc. Attempts at developing adhesive systems for bonding to dentin have resulted in the availability of a large range of materials and procedures, and research is being carried out even today. Topographic variety, chemical composition richer in organic substances and water, and the presence of dentinal fluid or of the so-called “smear” layer (discovered and named in the literature by Boyde in 1963) are some of the obstacles and challenges people have faced when trying to achieve an efficient bonding to the dentinal substrate.9,10 In 1970, Eick et al were the first to identify the chemical constitutive elements of the microscopic “smear” layer that covers the dentin after cavity instrumentation. In 1984, Brännström divided the layer into two parts, depending on their location: “smear on” – the part located on the dentin walls – and “smear in” – the extension of the former into the dentinal tubules. Nowadays, the most popular terms used in the literature are “smear layer” for the detritus film on the dentinal surface, and “smear plugs” for the material packed into the dentinal tubules (such as “corks” or “plugs”).6,11,12 The almost unanimously acknowledged attribute of the smear layer to protect the pulp-dentin system by decreasing dentin permeability led the specialists to initially ignore Fusayama’s suggestion (1980) to acid etch not only the enamel but also the exposed dentinal surfaces. This very controversial procedure was finally accepted, which resulted in “total etch” (or total acid etch).13 In 1952, Kramer and McLean made the first remarks concerning the presence of a hybrid layer when they noticed that the product developed by Hagger in 1949 had a tendency to penetrate the dentinal surface and form an intermediate area between the dentin and the restorative material. In 1982, Nakabayashi studied the characteristics of the hybrid layer, thus laying the foundation of the dentin hybridization theory. The formation of the hybrid layer eliminates the risk of marginal microinfiltration (regarded as the main source of pulpal

complications) and leads to an adhesive “attachment” between the substrate and the restorative material.14 The next crucial step regarding adhesion to the dentinal substrate was the introduction of bonding agents with self-etching primer, meant to prevent nanoinfiltration phenomena at the base of the hybrid layer, as well as postoperative pain or tooth sensitivity. Most manufacturers focused on this idea to simplify clinical procedures, namely to shorten the time required for resin application, and to prevent practice errors. Irrespective of the aforementioned advantages, the impact of bonding agents with self-etching primer on the quality of bonding to enamel is still under discussion, principally regarding the bond strength to the substrate.15 An analysis of the crucial moments in the history of bonding in restorative dentistry reveals, on the one hand, the constant attempts by scientists and biomaterials manufacturers to improve products and techniques in response to clinical practice demands, and, on the other, the fact that the research is far from over. The aim is to develop and introduce on a large scale the socalled “all-in-one” or “universal” adhesive, a single adhesive able to offer simple and efficient adhesion solutions for all kinds of substrates.

7.2 ADHESION TO HARD DENTAL TISSUES 7.2.1 Strategies in approaching adhesion to hard dental tissues The fundamental principle of adhesion to dental tissues is based on an exchange process by which inorganic dental material with a crystalline mineral structure is replaced by synthetic resin. The process involves two stages.16 The first stage (called “acid etching”) consists of the demineralization and removal of the calcium phosphate that makes up the hydroxyapatite crystals of the superficial layer, which results in microporosities on the surface of both enamel and dentin (Figs 7-1a to 7-1d).17,18 The second stage (defined as “hybridization”) consists of infiltration and in situ polymerization of monomeric resins within the created etch pits. In this way, bonding to the substrate is achieved through micromechanical interlocking that is chiefly based on mechanisms of diffusion. The latter aspect is regarded as a crucial sine qua non condition to achieving good bonding within clinical circumstances. The potential benefit of the additional chemical interaction between bifunctional monomers and tooth substrate constitutive elements has always been a main theoretical and practical concern, and is still a topic of contemporary research.

Fig 7-1 a Tooth 26: Acid etching of enamel.

Fig 7-1 b Acid etching of dentin.

Fig 7-1 c Post-etching clinical view.

Fig 7-1 d Post-bonding view. (Images courtesy of Dr Ionut Brânzan.)

In modern enamel/dentin bonding systems, the adhesive interface with the substrate is achieved by following several “steps”, which also represent a classification criterion for adhesives. In addition to the clinical “steps” (of which there could be three, two, or only one),

another essential criterion for defining and classifying bonding agents is the adhesion “strategy” underlying the therapeutic approach. In this regard, there are three classes of adhesives:20,22,24,64 • “etch-and-rinse” • “self-etch” • “glass-ionomer”. There are substantial differences between them concerning the degree of substance exchange and the way in which the exchange takes place at the interface between adhesive and tooth substrate (enamel/dentin, or possibly cement). In general, the exchange intensity induced by etch-and-rinse adhesives exceeds that of self-etch adhesives;19 nevertheless, among the latter there are currently some adhesives that intensely interact with the substrate, even when only applied in “one-step”.22,23 7.2.1.1 “Etch-and-rinse” bonding strategy This technique involves the application of the acid etchant as an initial, separate step, followed by substrate rinsing and water removal. The next steps consist of applying the primer, which is the diffusion-promoting agent indispensable to achieving adhesion, and finally the resin, which is the bonding agent proper. Thus, the etch-and-rinse strategy involves three separate steps, or two in the case of the simplified version when the primer and the bonding agent are mixed. The invariable and characteristic step is the compulsory and separate acid etching followed by rinsing. The approach, which basically only requires two steps, is still the most effective for achieving solid and stable bonding to enamel. Selective dissolution of hydroxyapatite crystals through etching (the most common is 30% to 40% phosphoric-acid gel) produces microporosities on the substrate surface, where the resin absorbed by capillary attraction is polymerized in situ and envelopes the remaining exposed crystals. The resin, infiltrated within the prismatic structures of the enamel, interlocks with the etch pits in two ways, forming macro- and microresin tags. The macro tags fill the space surrounding the enamel prisms, while the more numerous micro tags, which result from resin infiltration and polymerization within the small etch pits at the core of the etched enamel prisms, play a major contributory role in the micromechanical bonding between adhesive and enamel.24,25 With regard to dentin, the phosphoric-acid treatment exposes the collagen network that is nearly totally “depleted” of hydroxyapatite crystals, thus displaying numerous microporosities

within which nearly all calcium phosphates have been dissolved and removed. Consequently, the primary bonding mechanism of etch-and-rinse adhesives to dentin is first and foremost diffusion-based, and depends on the (as complete as possible) infiltration of resin within the exposed collagen fibril scaffold. Chemical bonding is rather unlikely and difficult, because the functional groups of monomers have less affinity to the hydroxyapatite-depleted collagen. This weak chemical interaction might be the main reason for the high long-term failure rate of the bonding between such adhesives and dentin.18,24,25 The main drawback of this technique is the significant delay between the moment when the microporosities are formed by acid etching and the moment when the monomeric resin infiltrates these gaps. In this time period, the conditions for filling the etch pits by diffusion must be created and maintained.

Fig 7-2 a Pre-acid etching clinical status.

Fig 7-2 b Etchant applied on tooth.

Fig 7-2 c Demineralized surface.

Fig 7-2 d Post-bonding view of the surface. (Images courtesy of Dr Florin Lazarescu.)

Consequently, the most critical step in the etch-and-rinse approach is the priming step. There are two techniques: dry-bonding and moist/wet bonding, depending on the solvent-based primer. Dry-bonding involves air-drying (not dehydration) of the acid-etched and washed dentin or enamel, followed by priming with a water/ethanol-based hydrophilic primer. Wetbonding involves removal (preferably by absorption) of excess water after rinsing the acidetched tooth, followed by the mandatory use of a hydrophobic and highly volatile acetonebased primer (Figs 7-2a to 7-2d). Both techniques involve “delicate” technical issues and there is a risk of errors during application and manipulation of the substances, which could lead to either deterioration of the hybrid layer, resulting in loss of marginal seal integrity (opening the way for nanoleakage), or postoperative pain, because of the dentinal fluid movement within dentinal tubules.23,26 7.2.1.2 “Self-etch” bonding strategy

Clinically, the self-etch bonding strategy is the most promising regarding user-friendliness and the reduction of technique-sensitivity. In such an adhesive system, low-pH etchers (functional monomers with one or more carboxylic or phosphate acid groups) are mixed with a self-etch primer. As no separate acid etching step followed by rinsing and drying is required, the clinical application time is reduced, and the risk of errors during application and manipulation is lowered.27–29 The self-etch approach involves two steps, or a single step in the case of the simplified version when the primer and the bonding agent are mixed. What is peculiar to this technique is the fact that the mandatory separate etching stage followed by rinsing is no longer present.30,31 As the infiltration of resins occurs simultaneously with the etching process in this bonding strategy, the problems related to the delay between the emergence of etch pits following acid etching and monomeric resin infiltration within the gaps are largely diminished (if not completely removed). On the other hand, there is still the question of the long-term effects of incorporating dissolved hydroxyapatite crystals and residual smear-layer remnants within the bond. At the same time, it is important to know how much of the self-etching primer/adhesive solvent is retained within the interfacial structure. A solvent surplus will directly weaken the bond integrity (diminishing the bond strength at the substrate) and provide channels for nanoleakage, or it may inhibit the polymerization of the infiltrated monomers. Another significant aspect is related to the fact that the resultant interfacial structure is much more hydrophilic and, consequently, more prone to hydrolytic degradation. Self-etching acid monomers have various degrees of pH level. Depending on the etching aggressiveness, self-etch adhesives can be subdivided into two categories: strong and mild.32 Strong self-etch adhesives usually have a pH of 1 or below. This high acidity results in a rather deep demineralization effect. At the enamel layer, the resulting acid-etch pattern rather resembles the phosphoric-acid treatment following an etch-and-rinse approach, but is less deep and, consequently, less efficient with respect to the bond strength at the enamel layer by means of mechanical microinterlocking. At the dentin layer, collagen is exposed and nearly all hydroxyapatite crystals are dissolved. Consequently, the underlying bonding mechanism is chiefly diffusion-based, which is similar to the etch-and-rinse approach. Low-pH self-etch adhesives have often been documented with rather low bond-strength values at dentin. Besides the high initial acidity that results in a

weakened bonding performance, another problem is the effect of the residual solvent (water) of the self-etch primer that remains within the adhesive interface. The latter cannot be completely removed, which calls into question the long-term stability of this strong self-etch approach.30,31,33 Mild self-etch systems generally have a pH of around 2. On dentin, the demineralization is rather low, only to a depth of 1 µm. This superficial demineralization occurs only partially, keeping residual hydroxyapatite crystals still attached to the collagen network. Even under such circumstances, they produce enough etch pits to obtain micromechanical interlocking through hybridization. Although the hybrid layer is thinner than that produced by the strong selfetch, not to mention the etch-and-rinse approach, it does not have a decisive impact on the actual bonding effectiveness. The preservation of some amount of hydroxyapatite within the submicron hybrid layer may serve as a receptor for additional chemical bonding. Carboxylic acid-based monomers, such as 4-META, and phosphate-based monomers, such as phenyl-P and 10-MDP, have a chemical bonding potential to calcium of residual hydroxyapatite.34,35 There is a theory according to which a weak self-etching effect is desirable and useful because it solves several problems simultaneously: dealing with the smear layer that results from cavity preparation, achieving micromechanical interlocking within etch pits at the enamel layer, and producing a thin hybrid layer by infiltration within dentin etch pits. Micromechanical retention is mandatory in order to resist acute debonding forces at the adhesive interface. The exposed hydroxyapatite enamel surface and the hydroxyapatite crystals that remain around collagen in dentin (in the case of mild self-etching) offer the advantage of enabling more intimate chemical interaction with the functional acid monomers. However, the problem is how these interactions can result in long-term, stable calcium-carboxylate or calcium-phosphate bonds within a hydrophilic environment where they are subject to hydrolysis.

Fig 7-3 a Strong self-etch adhesive – Single Bond Universal Adhesive (3M).

Fig 7-3 b Mild self-etch adhesive – Clearfil S3 Bond (Kuraray).

Therefore, the bonding potential of the mild self-etch adhesives to enamel is weak. In order to solve these problems, self-etch adhesives have been improved by changing the pH of their primer to an intermediary value of around 1.5. This creates a more gradual transition at the dentin interface of the hybrid layer (almost complete demineralization) to the underlying unaffected dentin, reducing the long-term degradation potential. At the enamel layer, it enabled more efficient micromechanical interlocking, namely a higher bond strength (Figs 7-3a and 73b). 7.2.1.3 “Glass-ionomer” bonding approach In principle, glass ionomers are the only biomaterials that self-adhere to tooth structures without any surface pretreatment. However, pretreatment with weak polyalkenoic-acid conditioner significantly improves the bonding efficiency. Consequently, the glass-ionomer approach can be achieved following a one- or two-step application procedure. The initial, surface-conditioning step becomes more important, when the tooth preparation produces more smear layer. In general, such a polyalkenoic-acid conditioner is applied for 10 to 20 seconds and rinsed off, followed by gentle air-drying without dehydrating the surface of the substrate.1,36 The increase in bonding efficiency that results can be partly attributed to a cleaning effect, by which debris is removed from the surface, to a demineralization effect, by which microporosities for micromechanical interlocking and hybridization are produced, and, above all, to the chemical interaction between polyalkenoic acid and residual hydroxyapatite. In this way, a network of hydroxyapatite-coated collagen fibrils interspersed by the micropores produced by the acid is exposed to a depth no deeper than 1 µm.

All experimental and laboratory investigations have demonstrated that this conditioner cannot be completely rinsed off; a layer up to 0.5 µm thick, referred to as a “gel phase”, remains attached to the tooth surface. The self-adhesion of glass ionomers to tooth structures has a twofold mechanism. The first consists of micromechanical interlocking achieved by a shallow hybridization of the microporous, hydroxyapatite-coated collagen fibril network. In this respect, glass ionomers can be considered as adhering to tooth structures through a “mild” self-etch approach, with the difference being that glass ionomers are self-etching through the use of a polycarboxyl-based polymer with a relatively high molecular weight, whereas resin-based self-etch adhesives make use of monomers with a much lower molecular weight.36

Fig 7-4 a Homogenous hybrid layer in intimate contact with enamel prisms.

Fig 7-4 b Hybrid layer with dehiscent areas at interface with tooth substrate. (Images courtesy of Prof Dr Ion Patrascu.)

The second component of the self-adhesion mechanism concerns chemical bonds, which are ionic and formed between carboxyl groups of the polyalkenoic acid and calcium of the

hydroxyapatite that remains around the exposed surface collagen. This aspect has been documented at both the enamel and dentin layers. Experiments have demonstrated that carboxyl functional groups interact with the hydroxyapatite surface. The interaction is strong enough to be recorded after ultrasonically rinsing off the polyalkenoic acid solution from the tooth substrate.2,36 The binding energy results from the oxygen and carbon atom interaction in the carboxyl group. An “adhesion-decalcification” model was proposed to explain why certain acids (such as the 10:1 acrylic/maleic acid) adhere to tooth tissue more than they decalcify it. This aspect depends upon the solubility of the formed calcium salt in its own acidic solution. The more soluble the calcium salts of the acids, the less it will adhere to the mineral substrate. As the calcium salts of the polyalkenoic acids are difficult to dissolve, they have an adequate chemical bonding potential to hydroxyapatite-based structures. Typical for glass-ionomer adhesion is the presence of a gel phase at the interface that represents the formation of a calcium polycarboxylate salt resulting from either the polyalkenoic acid conditioner or the glass-ionomer material itself. This phase has been proved to be stable and strong, an intermediary between the shallow 0.5 to 1 µm hybrid layer and the glass-ionomer matrix. Experimental research has confirmed that this structure is more resistant to tensile forces than the glass-ionomer matrix (Figs 7-4a and 7-4b). 7.2.2 Remarks on adhesion to enamel Buonocore demonstrated that acid etching of the enamel increased bond strength between etched enamel and composite resin.2,3,7,37 Initially, Buonocore used 85% phosphoric acid for tooth surface preparation; later, others experimented with hydrochloric, nitric, lactic, citric, pyruvic, and acrylic acid or EDTA.38–41 Several in vitro studies showed that a 35% to 37% concentration of phosphoric acid is best for acid etching of the enamel. Other studies did not document any correlation between phosphoric acid concentration and resistance to tensile force. The ideal length of time of etching is 20 to 40 seconds.2,37,41,42 Acids dissolve hydroxyapatite, the main mineral from which dental enamel is composed. Acid etching removes about 5 to 30 μm of the enamel surface.2,43,44 The amount of dissolved mineral and the depth of micromechanical retention, as well as the type of acid etching pattern, depend upon two categories of factors:

Fig 7-5 a-d Acid etching of the enamel – prisms cut longitudinally (a) and transversally (b to d) displaying the three acid etch patterns. (Images courtesy of Prof Dr Ion Patrascu.)

• Factors related to the enamel: structure; chemical composition; and surface texture. • Factors related to acid etching: type; concentration; pH; and length of time of etching.43 A scanning electron microscope (SEM) examination reveals that etched enamel surfaces have a characteristic appearance called an etching pattern (Figs 7-5a to 7-5d). There are three etching patterns resulting from the selective acid dissolution of prism cores or peripheral area (enamel rods and interrod enamel):2,4,41,45,46 • Type 1: a “honeycomb”-like appearance (preferential dissolution of prism core, leaving the periphery relatively intact). • Type 2: preferential dissolution of peripheral core material, leaving the prism core relatively unaffected. • Type 3: a random etching pattern.47,48 The bigger the difference between the acid solubility of enamel periphery and prism core, the stronger the micromechanical retention that is liable to enhance the contact surface with the adhesive, and therefore the stronger the bond. Following acid etching, the irregular enamel surface created by selective dissolution of either prism core or periphery (depending on the etching pattern – type 1 or type 2) has the best texture to facilitate mechanical retention and therefore ensure a strong bond.2,4 The chemical composition, histological structure, and microstructure of the enamel layer are substantially diverse. These factors determine selective acid dissolution of hydroxyapatite, which results in atypical etching patterns, such as type 3. In this case, both prism areas dissolve rather equally, the mineral loss is relatively uniform and, consequently, the etching

pattern does not always facilitate strong bonding by micromechanical interlocking.2,4 Following preferential and partial dissolution of prism hydroxyapatite crystals, the resultant etch pits will be filled with adhesive fluid components. Resin tags up to 25 μm in length and 6 μm in diameter are formed into the microporosities of the conditioned enamel. After adequate polymerization, they provide a long-lasting bond by mechanical interlocking. In this way, due to enhancing the contact surface with the adhesive, the formed resin tags significantly improve bond strength.2–4,7,41,45,49 Laboratory studies of enamel acid etching have determined that the mean values of tensile and shear stress amount to at least 20 to 25 MPa. These forces at the resin-enamel interface are higher than the surface tension following polymerization shrinkage of the composite resin (approximately 16 to 18 MPa).1,2,4,45 Acid etching increases surface tension of the enamel, which brings about a decrease in the contact angle between the liquid adhesive and the enamel surface from 22 to 23 degrees to 5 to 6 degrees, namely an increase in wettability. As compared to dentin, the prevailing mineral structure of the enamel determines its lower permeability to liquids.1,4,50 The structure of hydroxyapatite favors the chemical bonding of composite restorations to the etched enamel through a liquid resin with high wettability. The bonding agents are unfilled acrylic resins that contain the same monomers as the restoration composite resin, but there is more dilute monomer added in order to reduce viscosity.2 Several methods of achieving bonding to enamel have been experimented with in the past using various bonding agents to bind the CaOH groups of the hydroxyapatite: usually an organic or inorganic acid group represented by polymerizable compounds of organic (mostly phosphoric) acids able to bind calcium ions. There are several bonding agents: aminotriacetic acid, ethylenediamine tetraacetic acid, N(2-hydroxy-3-methacryloxypropyl)N-phenylglycine, and phosphoric acid derivatives, such as glycerophosphoric acid dimethacrylate. In conclusion, due to its prevalently mineral composition and specific texture, as well as the constructive structure changes inflicted by acid etching, enamel is an adequate substrate for mechanical bonding with adhesive resin by specific and chemical bonds. Most adhesive procedures in esthetic restoration dentistry are based on using enamel as a support for adhesive resin, which nowadays gives far better results than dentin.2,4 In order to improve adhesion and marginal sealing, acid etching requires as large an enamel surface as possible to be available for conditioning. In the case of anterior teeth, the available

bonding enamel surface is quite small, therefore beveling of the enamel margin is required. For the posterior teeth, the procedure is not always recommended due to the force created by the dynamic action of the masticatory muscles during chewing. Moreover, a marginal bevel in the anterior teeth will improve the esthetic aspect of the restorations due to the gradual transfer from enamel to resin, which is more pleasing to the eye.2 Acid etching of the enamel is a very popular clinical procedure, the large-scale use of which led to increased longevity of composite resin restorations by decreasing marginal microleakage, recurrent caries, and postoperative sensitivity due to better marginal sealing at the enamel margin of the preparation.1 In theory, adhesion to demineralized enamel requires a dry surface in order to allow the hydrophobic light-cured bonding agent to penetrate into the etch pits by capillary attraction. There are two types of resin tags:

Fig 7-6 Smear layer – demineralized dentinal debris.

Fig 7-7 Degree of penetration of the demineralizing agent into the lateral (a) and pulpal (b) dentinal wall. (Images courtesy of Prof Dr Ion Patrascu.)

• Macrotags: formed around the enamel prism peripheries. • Microtags: formed at the cores of the enamel prisms, where the resin has penetrated into the numerous microporosities created by the dissolution of the hydroxyapatite crystals. Even though most studies and research concerning adhesion techniques have chiefly focused on bonding to dentin, the importance of bonding to enamel cannot be overlooked in the wake of the development of new adhesive systems. Enamel bonding is, clinically speaking, the most significant. Therefore, the central rule in cavity preparation for adhesive restoration is to have as large an enamel surface as possible for adhesion. 7.2.3 Remarks on adhesion to dentin In contrast to enamel, dentin has a different response to adhesion due to its structure and chemical composition, so that bonding is much more difficult to achieve. While enamel is predominantly mineral, dentin is a vital tissue. The permeability of dentin depends on the number and diameter of the dentin tubules. The continuous flow of dentinal fluid leads to a permanent modification of the surface and dilution of the applied substances.2,41 Following preparation, a microscopic layer of remnant debris, known as the smear layer, is deposited on the dentin. It is a thin layer consisting of microcrystalline particles enveloped in a modified organic matrix, which results from the friction, vibration, and heat produced during preparation. The smear layer looks like a porous, amorphous, and relatively flat structure with a thickness of between 0.5 and 5 μm. It consists of:41

• Enamel and dentin debris: hydroxyapatite crystals, altered denatured collagen, smear debris from inter- and peritubular dentin, glycosaminoglycans and proteoglycans, residues from the odontoblasts, and bacteria. • Extra dental debris: saliva, blood, and pulp tissue debris. The smear layer extends 1 to 10 μm into the initial part of the dentin tubules, forming “smear plugs”.2,37,51 The thickness and morphology of the smear layer depends on the abrasives used. In vitro studies have shown that the thickness of the smear layer is in direct proportion to the grain size of the bur: for instance, a yellow ring 100 μm diamond bur produces a smear layer that is 2.2 ± 0.5 μm thick.37,52 The smear layer has a weak bond to the underlying dentin and, even though it might initially protect damaged dentin, preventing bacterial invasion into the tubules and variation in the dentinal fluid flow, it also prevents micromechanical or chemical bonding between dentin and adhesives. This is the major drawback of adhesion to dentin (Fig 7-6).37,45 For a long time, acid etching was believed to be harmful to the pulp; moreover, some believed that even acid etching of the enamel was barely possible without involving or affecting the dentin. The scientist who first asserted and proved that acid etching of dentin is possible was Fusayama, who developed the “total-etch” technique; in this way, tensile bond strength values could be increased from 16.8 kgf/cm2 to 62.3 kgf/cm2.2,13,41,53 The results of the total-etch procedure include: • A 3 to 5 μm deep demineralization area in the dentin,1,54 the depth of which depends on the type, concentration, pH, and viscosity of the acid, as well as the length of time of etching (Figs 7-7a and 7-7b).41,55,56

Fig 7-8 Pulpal dentinal walls – demineralized dentin and penetration of the hybrid layer into dentinal tubules. (Images courtesy of Prof Dr Ion Patrascu.)

• Complete exposure of the collagen fibrils due to the dissolution of the surrounding hydroxyapatite.41,45,55,56 A bond between the conditioned dentin surface and the restoration resin-based composite material is formed through a dentin adhesive that contains hydrophilic chemical groups that will interact with the wet dentin surface, as well as hydrophobic monomers to bond to the hydrophobic resin matrix.3,57 An example of such an acrylic monomer is HEMA, often used in adhesive systems due to the above-mentioned chemical properties. Adhesive systems for dentin have hydrophilic components dissolved in an organic solvent able to remove moisture from the acid-etched dentin. In this way, they promote bonding to periand intertubular dentin, creating an interdiffusion zone amid collagen fibrils, resulting in an intermingled link between the collagen matrix of the dentin and the resin penetrated into the microretention areas (Fig 7-8). This transitional intermingled structure was first described in 1982 by Nakabayashi et al and called the “hybrid layer”, its thickness ranging between 1 and 5 μm.1–3,14,41 The hybrid layer has manifold functions:58 • It provides micromechanical and/or chemical bonds to the restorative resin-based material. • It restores the mechanical properties of the partially demineralized dentin at the level before demineralization. • It protects collagen fibrils inside the layer against subsequent alteration, fulfilling the same function as the hydroxyapatite of the normally mineralized dentin.

Many factors influence the formation of a hybrid layer, such as the length of time of etching and the concentration of the acid. The presence of decalcified dentin at the bottom or below the hybrid layer weakens the dentin bond strength with time because the remnant decalcified layer will not be impregnated by resin. Another aspect that has a significant impact on hybrid layer formation is the excessive dryness of dentin before the application of the bonding agent, causing the exposed collagen fiber network to collapse and block the access of the adhesive to the dentin areas below.1,2,59 The capacity of the adhesive monomers to fill the space that results from acid etching and envelop exposed collagen fibrils has a significant influence on the bond strength of the dentinadhesive interface.60 7.2.4 Current status of adhesion to enamel/dentin Initially, clinical and experimental studies demonstrated that adhesive bonding was weaker to dentin (both immediately and with time) than to enamel. Modern adhesive systems to enamel/dentin are able to create similarly strong bonds to dentin and acid-etched enamel. For a long time, adhesion to dentin was a real challenge for restorative dentistry because the techniques that were being used produced unsatisfactory results. These techniques were based on the preservation of the smear layer so that the adhesive systems had to form chemical bonds (esteric, aminic, phosphatic, isocyanatic, and glutaraldehydic) with the mineral or organic dentin components. The bonds were rather weak and the dentinal fluid could easily dehydrolyze them, resulting in adhesive or cohesive cracks at the dentin-resin interface. With the development of the total-etch technique, the adhesion to dentin was substantially improved. The emergence of a hybrid layer following the micromechanical interlocking between the adhesive system and dentinal collagen, and the penetration of resin tags into dentinal tubules, enabled the creation of insoluble acid-resistant structures. Nevertheless, micro- and nanoleakage phenomena still pose major theoretical and clinical challenges.19 According to the presentation and number of application steps, correlated with the generation to which they belong, the currently used adhesives to enamel/dentin are classified into the following types: • Type I. • Type II. • Type III. • Type IV.

7.2.4.1 Type I adhesive systems Type I adhesive systems are etch-and-rinse systems (etchant applied separately, followed by rinsing off and drying after acid demineralization) that belong to the fourth generation and are applied separately and successively in three steps: etchant + primer + resin. The main characteristics in the clinical use of type I adhesive systems are that they: • Are packaged in separate bottles (etchant, primer, and bonder). The etchant is contained in easy-to-use syringes with fine syringe tips for precise controlled placement. • Require a separate acid conditioning (etching) step. • Require a separate acid rinsing (with water) step. • Are light- or dual-curing systems (light-/self-curing).

Fig 7-9 Three-step etch-and-rinse adhesive system – Optibond FL (Kerr).

Fig 7-10 Two-step etch-and-rinse adhesive system – Excite F (Ivoclar Vivadent).

• Can be used in all adhesive procedures: direct, semi-direct, and indirect (Fig 7-9).61–64

7.2.4.2 Type II adhesive systems Type II adhesive systems are etch-and-rinse systems (etchant applied separately, followed by rinsing off and drying after acid demineralization) that belong to the fifth generation and are applied in two steps: etchant/primer + resin. The main characteristics in the clinical use of type II adhesive systems are that they: • Are packaged in one bottle (primer plus resin), while the etchant comes in easy-to-use syringes with fine syringe tips for precise controlled placement. • Require a separate acid conditioning (etching) step. • Require a separate acid rinsing (with water step). • Are light-curing systems (there might be an additional catalyst for dual-curing: light-/selfcuring, but the results are not promising). • They can be used in direct adhesive procedures, with light-curing restoration resins (Fig 7-10).61–64 7.2.4.3 Type III adhesive systems Type III adhesive systems are self-etch systems (do not require separate acid etching, the first step being the application of a self-curing acid primer that requires no rinsing off and drying after acid demineralization) that belong to the sixth generation (“two-step” type I) and are applied in two steps: etchant + primer/resin. The main characteristics in the clinical use of type III adhesive systems are that they: • Are packaged in two bottles (self-curing acid primer, and resin). • Do not require a separate acid conditioning (etching) step. • Do not require a separate acid rinsing (with water) step. • Are applied separately: first the self-curing primer, then the resin. • Are light-curing systems (there might be an additional catalyst for dual-curing: light-/selfcuring). • Can be used in all adhesive procedures: direct, semi-direct, and indirect (Fig 7-11).61–64

Fig 7-11 Two-step self-etch adhesive system – Clearfil SE Bond (Kuraray).

Fig 7-12 One-step self-etch adhesive system – G-Bond (GC).

7. 2.4.4 Type IV adhesive systems Type IV adhesive systems are self-etch systems (do not require separate acid etching that are applied in one step: etchant + primer + resin and belong to the sixth (“one-step” type II) and seventh (“all-in-one”) generations. The adhesives belonging to the two different generations require different application techniques: in the case of the type IV sixth generation, the self-curing primer is mixed with the resin when used; in the case of the seventh generation, the three constitutive elements are mixed together by the manufacturer. Therefore, the characteristics in their clinical use are different. The main characteristics in the clinical use of type IV, sixth generation adhesive systems, are that they: • Are packaged in two bottles (self-curing acid primer, and resin). • Do not require a separate acid conditioning (etching) step. • Do not require a separate acid rinsing (with water) step.

• Are applied simultaneously and require mixing (when used). • Are light-curing systems. • Can be used in direct adhesive procedures with light-curing restoration resins. The main characteristics in the clinical use of type IV, seventh generation adhesive systems, are that they: • Are packaged in one bottle (self-curing acid primer plus resin). • Do not require a separate acid conditioning (etching) step. • Do not require a separate acid rinsing (with water) step. • Are applied simultaneously; they do not require mixing (are monocomponent), and the onedose package is the best presentation. • Are light-curing systems. • Can be used in direct adhesive procedures, with light-curing restoration resins (Fig 712).19,64

7.3 ADHESION TO CERAMIC2 The parallel between phosphoric-acid-etched enamel and hydrofluoric-acid-etched porcelain in the early 1980s stimulated the development of bonded ceramic restorations.65,66 Adhesion to porcelain can be achieved by micromechanical and/or chemical bonding. In order to achieve optimal bonding and improve mechanical attachment, the porcelain surface has to be conditioned to become microretentive. Surface preparation techniques include acid etching (with hydrofluoric acid), laser etching (Er:YAG), and sandblasting with aluminum oxide particles. The impact of these surface treatments on the adhesion depends on the type and microstructure of the ceramic surface.37,45,67 For a long time, hydrofluoric acid was most commonly used for etching indirect ceramic restorations (Figs 7-13a to 7-13f).37,66 As an alternative to hydrofluoric acid, in order to prevent risks related to its use, acidulated phosphate fluoride and phosphoric acid were used in porcelain surface preparation, but with no noticeable improvement in bond strength. Phosphoric acid is used in industry to etch glass at a high temperature. At room temperature, its action is limited to cleaning the ceramic surface and, therefore, this treatment does not contribute to the resin-ceramic bond.2,37,68,69 The capacity of hydrofluoric acid to alter the ceramic surface is closely connected to the ceramic microstructure and composition. Ceramic that contains a glass phase (leucite, silicabased feldspathic, or glass ceramics) can be etched with hydrofluoric acid, whereas aluminabased all-ceramic restorations cannot be etched sufficiently, and zirconia-based ceramics cannot be etched at all. The hydrofluoric acid creates a surface pattern for micromechanical attachment by preferential dissolution of the glass phase from the ceramic matrix, which increases the surface area and enhances the micromechanical retention of the resin cement.23,36,70 The micropits formed on the ceramic surface by hydrofluoric acid etching allow the penetration of both the resin and filler components of the luting composite cement to form resin tags that contribute to strengthening the resin-ceramic bond.37,71 Due to this ability of the filler to penetrate the micropits without being filtered, their resinceramic bond strength can be substantially increased by treating the etched ceramic with filled bonding agent. However, overetching with high concentrations of hydrofluoric acid, or extended etching times, may lead to reduced bond strength. On the other hand, hydrofluoric

acid can be so aggressive to the surface of some ceramic materials that it decreases its mechanical properties, which in turn affects the resin-ceramic bond strength. Consequently, the type of ceramic used should be taken into consideration before hydrofluoric acid etching.37,67,72–74

Fig 7-13 a Hydrofluoric acid etching of the ceramic surface.

Fig 7-13 b Ceramic surface after hydrofluoric acid etching.

Fig 7-13 c Immersion of ceramic restoration into ultrasonic bath.

Fig 7-13 d View after removal of ceramic restoration from ultrasonic bath.

Fig 7-13 e Post-silane application view.

Fig 7-13 f Post-bonder application view. (Images courtesy of Dr Ionut Brânzan.)

An effective and long-lasting resin-ceramic bond is based not only on micromechanical bonding but also on chemical bonding. The most common and successful way to achieve a chemical resin-ceramic bond is by using silane coupling agents. They are bifunctional molecules that improve the wettability of the ceramic surface and form a covalent bond with both the ceramic and the resin cement.37,75 The most common silane agent used in dentistry is γ-methacryloxypropyl-trimethoxysilane (γ-MPTS) in a solution of ethanol in water.37,45 It is manufactured either prehydrolyzed (packed in one container) or in a form that requires hydrolyzation by mixing silane with acid (two containers).76,77 The reaction between methoxy groups of γ-MPTS and OH groups of the porcelain surface that form bonds can be initiated and accelerated by using acid catalysis.37,76 At present, contemporary ceramic primers utilize separate acidic catalyst liquids, such as the monomer of 10-methacryloyloxydecyl dihydrogen phosphate (MDP), or carboxylic compounds. When the acidic catalyst is mixed with the silane coupling component, the methoxy groups hydrolyze to initiate a stable bond (Si–O–Si) with the porcelain surface.

Fig 7-14 a Initial status of tooth 26.

Fig 7-14 b Pressed all-ceramic restoration.

Fig 7-14 c All-ceramic restoration prepared for hydrofluoric acid application.

Fig 7-14 d Hydrofluoric acid applied on ceramic restoration.

Fig 7-14 e Rubber dam isolation of tooth 26.

Fig 7-14 f Post-sandblasting tooth 26. (Images courtesy of Dr Ionut Brânzan.)

Accordingly, ceramic primers can be classified as follows:78 • Unhydrolyzed single-liquid silane primer. • Prehydrolyzed single-liquid silane primer.

• Two- or three-liquid primer with separate silane coupler and acid activator. The single-liquid prehydrolyzed silane primer has shown a much better bonding performance than the unhydrolyzed form. However, the stability of the prehydrolyzed silane primer seems to be insufficient and it has a limited shelf life compared to the multicomponent liquid primers.78 Etching and silane treatment are best accomplished after the try-in procedure to prevent contamination of the conditioned ceramic surface. Nevertheless, for the convenience of dental practitioners and to save time, many commercial dental laboratories etch and silanize the inner ceramic surface of the restoration. When this pretreated surface is contaminated with saliva or blood during the try-in procedure, the surface has to be cleaned and silanized again before the application of the adhesive cement. Cleaning can be carried out with phosphoric acid and/or acetone, after which the silane has to be reapplied (Fig 7-14a to 7-14j).37

Fig 7-14 g Application of composite resin into cavity.

Fig 7-14 h Removal of excess cement before final polymerization.

Fig 7-14 i Final polymerization.

Fig 7-14 j Post-hydration restoration. (Images courtesy of Dr Ionut Brânzan.)

Due to the high concentration of various solvents within the silane coupling agents, an improperly sealed container will allow evaporation of the solvent, which increases the concentration of the coupling agent, which in turn can act as a separation medium and adversely affect the resin-ceramic bond.79 Improvement in resin-ceramic bond strength can also be accomplished through heat treatment of the silanized porcelain.65 It is believed that during heating, water and other contaminants, such as alcohol or acetic acid, are eliminated.37,75 The temperature of the air used to dry silanized ceramic ranges between 38ºC, 45ºC and 100ºC.70,80,81 High bond strength is recorded when heating is accompanied by hydrofluoric acid etching and abrasion. The shortcomings of hydrofluoric acid use are high toxicity, and the formation of insoluble hexafluorosilicate salts that cling to the ceramic surface, which, if not removed (best with distilled water in an ultrasonic cleaner), affect the resin-ceramic bond strength. In order to avoid hazardous hydrofluoric acid, an investigation was initiated to find out whether

silanization or silanization and heating, without other additional micromechanical bonds, are prone to ensuring solid resin-ceramic bond strength. The research revealed that the highest resin-ceramic bond strength is achieved by using abrasion with fine-grit paper, sandblasting, hydrofluoric acid etching, and silanization.2,37,65,76,80,82,83 Hydrofluoric acid etching followed by silanization does not improve the resin bond strength to alumina-based ceramics, probably due to the inherent microstructure of the ceramic, which is more resistant to the hydrofluoric acid. Moreover, as a consequence of the small percentage of silica at the surface of alumina-based ceramics, it is less likely that silane treatment can initiate effective chemical bonding. Tribochemical application of a thin silica layer by means of sandblasting (Rocatec system, 3M ESPE) followed by silane application is used to provide a long-term durable bond of BIS-GMA composite resin cement to alumina-based ceramic.37,84

Fig 7-15 a–d All-ceramic restoration-porcelain interface – resin cement seen under an ESEM microscope at various enamel and dentin layers. (Images courtesy of Prof Dr Ion Patrascu.)

In addition, the ability of the phosphate ester group contained in some adhesive resin-based cement to bond directly to metal oxides can also offer an alternative bonding mechanism to sandblasted alumina-based ceramic. The adhesive systems for ceramics can be used for bonding ceramic inlays and onlays, veneers, all-ceramic crowns, and ceramic brackets (Figs 7-15a to 7-15d).

Fig 7-16 a, b Clinical all-ceramic restoration by using adhesive bonding techniques.

7.4 CONCLUSION There is a large variety of adhesives that can be classified into different categories based on their adhesion mechanisms, such as “etch-and-rinse”, “self-etch”, and “glass-ionomer”. There is a definite tendency towards simplification of the procedure by decreasing the number of steps. Simplification does not necessarily imply the increase or maintenance of bonding strength and effectiveness. Consequently, two- and three-step “etch-and-rinse” (“total-etch”) adhesive systems are preferred in clinical practice because of their predictable and controllable technique sensitivity, as well as the positive results of clinical trials and experimental studies. For that reason, several authors still believe them to be a milestone (the “gold standard”) in enamel-dentin adhesion, principally regarding their bonding strength and long-term performance. Nowadays, there are still major shortcomings, among them the relatively high technique sensitivity of current systems, and the challenge of achieving an equally efficient adhesion to both enamel and dentin. Resin- or glass-ionomer-based self-etch adhesives have the best future perspective regarding these drawbacks. They do not require a rinsing step, which is timesaving, and are less exposed to the risk of making manipulative errors. In addition, there is no significant discrepancy between demineralization and infiltration. They ensure a twofold adhesion, on the one hand, through micromechanical interlocking by hybridization, in order to withstand the “acute” shock of debonding. On the other hand, they promote a good interaction between monomer and collagen by chemical bonding, which could help to maintain a marginal leakage-free restoration for quite a long time. In the last 4 to 5 years, there have been more and more discussions regarding “universal adhesives”. These bond to any dental substrate, including enamel, dentin, cement, metal, resins, ceramic, and zirconia, by using a single application technique. Concerning adhesives, the term “universal” is not new. However, there is still no generally acknowledged definition for such an adhesive. From the beginning of 2014, the definition should include the possibility: • To work with etch-and-rinse (total-etch), self-etch and selective-etch techniques. • To work with light-, self-, and dual-curing materials (without requiring an additional activator). • To be used in direct, semi-direct and indirect restorations.

• To work with all substrates in one application. As early as November 2011, at least two such adhesives were introduced into current practice. The future will demonstrate to what extent the present evolution of enamel-dentin adhesives fulfills our expectations. In conclusion, adhesive esthetic restorations have many advantages (Figs 7-16a and 7-16b) over non-adhesive restorations, apart from the fact that they cannot be carried out in a simple manner, or be performed too quickly, as this may adversely affect the quality, effectiveness, and durability of the restorations.

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24. Blunck U. Adhesives: Principles and state of the art. In: Roulet JF, Degrange M (eds). Adhesion: The Silent Revolution in Dentistry. Chicago: Quintessence, 2000:29–44. 25. Borgia BE, Busato ALS, Costa CAS, et al. Adhesión en Odontología Restauradora, Parana: GHH, 2003. 26. Hiraishi N, Breschi L, Prati C, King NM. Technique sensitivity associated with air-drying of HEMA free, singlebottle, one-step self-etch adhesives. Dent Mater 2007;23:498–505. 27. Perdigao J, Geraldeli S. Bonding characteristics of self-etching adhesives to intact versus prepared enamel. J Esthet Restorative Dent 2003;15:32–41. 28. Perdigao J. Lopes MM, Gomes G. In vitro bonding performance of self-etching adhesives: Ultramorphological evaluation. Oper Dent 2008;33:534–549. 29. Suh B. Current status of self-etching primers adhesive systems. Odontoiatria adesiva e ricostruttiva: Atti del VI Simposio Internationale di S. Margherita 2002;3-4:42–52. 30. De Munch J, Sathosi I, Vargas M, Lambrechts P, Vanherle G. Microtensile bond strengths of one- and twostep self-etch adhesives to bur-cut enamel and dentin. Am J Dent 2003;16:414–420. 31. Di Hipolito V, Chan DC, Daronch M, Sinhoreti MA. SEM evaluation of contemporary self-etching primers applied to ground and unground enamel. J Adhes Dent 2005;7:203–211. 32. Moura SK, Pelizzaro A, Dal Bianco K. Does the acidity of self-etching primers affect bond strength and surface morphology of enamel? J Adhes Dent 2006;8:75–83. 33. Fabianelli A. Efficacy of self-etching primers on sending margins of class II restorations. Am J Dent 2003;1:37–41. 34. Watanabe I, Nakabayashi N, Pashley DH. Bonding to ground dentin by Phenyl-P self etching primer. J Dent Res 1994;73(6):1212–1220. 35. Yoshida Y, Nagakane K, Fukuda R, Okazaki M, Inoue S. Comparative study on adhesive performance of functional monomers. J Dent Res 2004;83:454–458. 36. Powers JM, Farah JW, O’Keefe KL, Kolb B, Udrys G. A Guide to All-Ceramic Bonding. Ann Arbor: Dental Consultants, Inc (The Dental Advisor), 2011. 37. Eliades GC, Watts DC, Eliades T. Dental Hard Tissues and Bonding: Interfacial Phenomena and Related Properties. Heidelberg: Springer, 2005. 38. Blosser RL. Time dependence on 2.5% nitric acid solution as an etchant on human dentin and enamel. Dent Mater 1990;6:83–87. 39. McLean JW. Status report on the glass ionomer cements. J Am Dent Assoc 1979;99:221–226. 40. Poole, DF, Johnson NW. The effects of different demineralizing agents on human enamel surfaces studied by scanning electron microscopy. Arch Oral Biol 1967;12:1621–1634. 41. Shalaby WS, Salz U. Polymers for dental and orthopedic applications. CRC Press: Boca Raton; 2007. 42. Gardner A, Hobson R. Variations in acid-etch patterns with different acids and etch times. Am J Orthod Dentofacial Orthop 2001;120:64–47. 43. Gwinnett A. Structure and composition of enamel. Oper Dent 1992;17:10–17. 44. Lees S, Rollins F. Anisotropy in hard dental tissues. J Biomech 1972;5–6:557–566. 45. McCabe JF, Walls WG. Applied Dental Materials, ed 9. Oxford: Blackwell, 2008. 46. Carvalho R. Effects of prism orientation on tensile strength of enamel. J Adhes Dent 2000;2–4:251–257. 47. Shimada Y, Tagami J. Effects of regional enamel and prism orientation on resin bonding. Oper Dent 2003;28:20–27.

48. Silverstone L. Variation in pattern of etching of human dental enamel examined by scanning electron microscopy. Caries Res 1975;9:373–387. 49. Gwinnett A, Matsui A. A study of enamel adhesives. The physical relationship between enamel and adhesive. Arch Oral Biol 1967;12:1615–1620. 50. Armengol V, Laboux O, Weiss P, Jean A, Hamel H. Effects of Er:YAG and Nd:YAP laser irradiation on the surface roughness and free surface energy of enamel and dentin: An in vitro study. Oper Dent 2003;28:67–74. 51. Pashley D, Tao L, Boyd L, King G, Horner J. Scanning electron microscopy of the substructure of smear layers in human dentine. Arch Oral Biol 1988;33:265–270. 52. Tani C, Finger W. Effect of smear layer thickness on bond strength mediated by three all-in-one self-etching priming adhesives. J Adhes Dent 2002;4:283–289. 53. Smidsederer I. Dentistrie Estetique. Paris: Elsevier Masson, 2000:118–136. 54. Gwinnett A. Smear layer: Morphological considerations. Oper Dent 1984;3:3–12. 55. Van Meerbeck B, Inokoshi S, Braem M, Lambrechts P, Vanherle G. Morphological aspects of the resin-dentin interdiffusion zone with different dentin adhesive systems. J Dent Res 1992;71:1530–1540. 56. Priotto E. Morphological and numerical characteristics of dentine tubules destined to adhesion. J Dent Res 1995;74:734. 57. Giannini M. The influence of tubule density and area of solid dentin on bond strength of two adhesive systems to dentin. J Adhes Dent 2001;3–4:315–324. 58. Curtis RV, Watson TF. Dental biomaterials: Imaging, testing and modelling. Cambridge: Woodhead, 2008. 59. Migues P, Castro P, Nunes M, Walter P, Pereira P. Effect of acid-etching on the enamel bond of two selfetching systems. J Adhes Dent 2003;5:107–112. 60. Pashley D, Agee KA, Carvalho RM, Lee KW, Tay FR, Callison TE. Effects of water and water-free polar solvents on the tensile properties of demineralized dentin. Dent Mater 2003;19:347–352. 61. Heymann HO, Swift Jr EJ, Ritter AV. Sturdevant’s Art and Science of Operative Dentistry, ed 6. St Louis: Mosby Elsevier, 2013. 62. Hilton TJ, Ferracane JL, Broome J. Summit’s Fundamentals of Operative Dentistry: A Contemporary Approach, ed 4. Chicago: Quintessence, 2013. 63. Mangani F, Putignano A, Cerutti A. Guidelines for Adhesive Dentistry. The Key to Success. Chicago: Quintessence, 2009. 64. Silva e Souza MH Jr, Carneiro KGK, Lobato MF, Silva e Souza Pde A, de Góes MF. Adhesive systems: Important aspects related to their composition and clinical use. J Appl Oral Sci 2010;18:207–214. 65. Fabianelli A, Pollington P, Papacchini F. The effect of different surface treatments on bond strength between leucite reinforced feldspathic ceramic and composite resin. J Dent 2010;38:39–43. 66. Horn HR. Porcelain laminate veneers bonded to etched enamel. Dent Clin North Am 1983;27:671–684. 67. Della Bona A, Anusavice KJ, Shen C. Microtensile strength of composite bonded to hot-pressed ceramics. J Adhes Dent 2000;2:305–313. 68. Kato H, Matsumura H, Atsuta M. Effect of etching and sandblasting on bond strength to sintered porcelain of unfilled resin. J Oral Rehabil 2000;27:103–110. 69. El Zohairy A, De Gee AJ, Feilzer A, Davidson CL. Long-term micro-tensile bond strength of resin cements bonded to CAD/CAM ceramic blocks. J Dent Res 2002;81:380–388. 70. Al Edris A, al Jabr A, Cooley RL, Barghi N. SEM evaluation of etch patterns by three etchants on three

porcelains. J Prosthet Dent 1990;64:734–739. 71. Peumans M, Van Meerbeek B, Yoshida Y, Lambrechts P, Vanherle G. Porcelain veneers bonded to tooth structure: An ultra-morphological FE-SEM examination of the adhesive interface. Dent Mater 1999;15:105–119. 72. El Zohairy A, De Gee AJ, Mohsen MM, Feilzer AJ. Microtensile bond strength testing of luting cements to prefabricated CAD/CAM ceramic and composite blocks. Dent Mater 2005;21:83–93. 73. Chen JH, Matsumura H, Atsuta M. Effect of etchant, etching period, and silane priming on bond strength to porcelain of composite resin. Oper Dent 1998;23:250–257. 74. Shimada Y, Yamaguchi S, Tagami J. Micro-shear bond strength of dual-cured resin cement to glass ceramics. Dent Mater 2002;18:380–388. 75. Roulet JF, Soderholm KJ, Longmate J. Effects of treatment and storage conditions on ceramic/composite bond strength. J Dent Res 1995;74:381–387. 76. Aida M, Hayakawa T, Mizukawa K. Adhesion of composite to porcelain with various surface conditions. J Prosthet Dent 1995;73:464–470. 77. Anagnostopoulos T, Eliades G, Palaghias G. Composition, reactivity and surface interaction of three dental silane primers. Dent Mater 1993;9:182–190. 78. Matsumura H, Kato H, Atsuta M. Shear bond strength to feldspathic porcelain of two luting cements in combination with three surface treatments. J Prosthet Dent 1997;78:511–517. 79. Barghi N. To silanate or not to silanate: Making a clinical decision. Compend Contin Educ Dent 2000;21:659– 662. 80. Monticelli F, Toledano M, Osorio Rand M. Effect of temperature on the silane coupling agents when bonding core resin to quartz fiber posts. Dent Mater 2006;22:1024–1028. 81. Shen C, Williams JR. Effect of post-silanization drying on the bond strength of composite to ceramic. J Prosthet Dent 2004;91:453–458. 82. Belli R, Guimaraes JC, Filho AM, Vieira LC. Post-etching cleaning and resin/ceramic bonding: Microtensile bond strength and EDX Analysis. J Adhes Dent 2010;12:295–303. 83. Douceta S, Taverniera B, Colona P, Picarda B. Adhesion between dental ceramic and bonding resin: Quantitative evaluation by Vickers indenter methodology. Dent Mater 2008;24:45–49. 84. Kern M, Strub JR. Bonding to alumina ceramic in restorative dentistry: Clinical results over up to 5 years. J Dent 1998;26:245–249.

(8.1) DIANA DUDEA, BOGDAN CULIC (8.2) BOGDAN DIMITRIU, CONSTANTIN VÂRLAN

Chapter VIII TOOTH DISCOLORATION

8.1 VITAL TOOTH DISCOLORATION

Fig 8-1 Professional prophylactic cleaning: a. Ultrasound scaling. b. Air abrasion.

Among the reasons that motivate patients to seek dental treatment is the need to improve their tooth color. Properly aligned, light-colored teeth are usually the gold standard regarding the smile’s appearance. The characteristics, as well as the importance, of dental color are undoubtedly differently perceived among individuals, both being influenced by factors such as culture, education, ethnicity, and age. However, it is unanimously recognized that the dental shape and color have a major influence on dental esthetics and, ultimately, upon the facial appearance. Consequently, methods aimed at improving dental color are particularly important in esthetic dental treatments. The treatment methods differ, according to the etiology of color changes, and range from oral hygiene products and prophylaxis to dental bleaching and/or restorative treatments (veneers, crowns). For the best outcome, these methods should be combined into an individual treatment plan

for each patient, in accordance with the etiology and severity of the respective discoloration. Consequently, before deciding the treatment plan, a thorough clinical examination is required in order to establish the etiology, the location of discoloration to one or several teeth, and the intensity of the color changes.1,2 8.1.1 Etiology of tooth discoloration Since the genetics of dental color are not fully understood, it is important to establish the influence of external factors on tooth color. According to the etiological factors and the mechanism of penetration and fixation of the coloring agents into the dental structure, tooth discoloration can be classified as extrinsic, intrinsic, or internalized.3–7 8.1.1.1 Extrinsic tooth discoloration Extrinsic tooth discoloration is caused by colorants incorporated into the mucoprotein pellicle that covers the dental surface. These stains can be removed by using oral hygiene products or prophylaxis (Figs 8-1a and 8-1b). They are mostly produced by food colorants (natural or synthetic), but also by drugs (eg, iron-based drugs), mouth rinses (chlorhexidine, listerine, stannous fluoride, phenolic/essential oil-based), or by the activity of chromogenic bacteria. The use of tobacco (cigarette, cigar, pipe smoking, tobacco or betel chewing) is also responsible for extrinsic and internalized discoloration (Figs 8-2a and 8-2b).8–10

Fig 8-2 Extrinsic tooth discoloration. a. Initially b. After professional cleaning. (Images courtesy of Dr Florin Lăzărescu.)

The Nathoo classification divides extrinsic discoloration into three categories:4,5 • Nathoo type 1 (N1). The colored substances adhere to the dental surface directly or through the salivary protein pellicle; the staining is similar in color to that of the chromogenic agent (tea, coffee, other colored food and beverages). • Nathoo type 2 (N2). These stains are caused by food colorants that change their color after fixing on the tooth surface. • Nathoo type 3 (N3). The discoloration is caused by colorless or pre-chromogenic substances that adhere to the dental surface (eg, chlorhexidine staining); subsequently, they induce a chemical reaction responsible for pigmentation. This category includes chlorhexidine, a cationic antiseptic used as an antibacterial mouth rinse, particularly in periodontal disease; its potential to stain the teeth, mucosa, as well as restorative materials (acrylates, composites) after several weeks of use is well documented.3–9 8.1.1.2 Internalized discoloration Internalized discoloration is caused by colorants from the oral environment that penetrate the enamel and dentin layers and bind chemically to hydroxyapatite and collagen in these structures. The adsorption of the staining molecules is due to the relative permeability of the enamel and, particularly, of the dentin; it is enhanced by structural defects occurring either during tooth formation or in a posteruptive stage.3,6,11 Therefore, in these patients, even if surface staining is removed through cleaning, color improvement can only be achieved by bleaching methods that remove pigments through a chemical mechanism (Figs 8-3a and 8-3b).

Both extrinsic and internalized discoloration depend not only on diet, oral hygiene habits, and dental structure, but also on other factors, including the composition of the mucoprotein pellicle on the enamel surface, responsible for the staining adsorption.12 Reduced salivary flow (in Sjögren syndrome, cervicofacial irradiation, or anticholinergic drugs) enhances the staining deposition. However, the wide range in dental color variation increases the difficulty of establishing the etiology and predicting the treatment outcome.3,7,11

Fig 8-3 a, b Internalized discoloration. (Images courtesy of Dr Florin Lăzărescu.)

8.1.1.3 Intrinsic tooth discoloration In these situations, the chromophore is attached to the mineralized dental structures, inducing an alteration of the light transmission. The colorant penetrates from the inside, as a result of pulp pathology (hemorrhage or necrosis, endodontic treatments), inducing local discoloration. Other causes of local discoloration are dental decays or restorative materials that can either stain the dental hard structures or cause shadows to be visible through the translucent enamel (see section 8.2). The discoloration may also have a systemic origin, which frequently induces

generalized staining of the dentition. Consequently, depending on the etiology, color changes may affect a single tooth, a group of teeth, or the full deciduous or permanent dentition. The intrinsic discoloration is caused either by factors that act during the formation and mineralization of the tooth or by posteruptive events. 8.1.1.4 Pre-eruptive action factors The factors with a pre-eruptive action may have different origins and pathogenic mechanisms, which explains the variation in the whitening response to chemical treatments. Thus, certain discolorations are the result of inclusion in the dental structures of substances from abnormal metabolic chains: hyperbilirubinemia in hemolytic anemia or hemolytic jaundice; thalassemia; congenital erythropoietic porphyria; and alkaptonuria. These forms are rare and usually associated with generalized discoloration. Developmental defects of the enamel and dentin, affecting either their organic or inorganic component, may induce white, yellow or brown discoloration that is variable in depth and more or less progressive in time. In these cases, staining is caused by the increased fixation of food colorants to the porous enamel or dentin. These spots can be removed by microabrasion or chemical treatment, but the results are unpredictable. Chemicals that attach most often to the developing dental tissues are drug molecules (antibiotics – tetracycline in different formulas, or iron-based medication) (Figs 8-4a and 84b). Tetracycline discoloration is due to its administration during tooth formation, but also after the tooth has erupted. The pathogenic mechanism is explained by chelation of the tetracycline molecule by the calcium ions in the hydroxyapatite of the enamel and dentin. Staining depends on the patient’s age, the duration of the administration, and the tetracycline derivative (tetracycline achromycin – yellow staining; tetracycline minocycline – black staining).11

Fig 8-4 a, b Discoloration induced by tetracycline.

Tetracycline discoloration includes mild or moderate stains, uniformly distributed on the dental surface, or more severe cases characterized by horizontal bands parallel to the incisal edge. A characteristic of tetracycline discoloration is the fluorescence, which becomes visible in UV light. Stains are more intense in anterior teeth and become darker in time due to photooxidation under daily light exposure. Tetracycline administration should be avoided up to the age of seven. Also, due to the risk of transplacental passage, this class of antibiotics is restricted during pregnancy. Tetracycline discolorations need longer exposure to bleaching products, have an unpredictable evolution, and have frequent postbleaching relapses. Minocycline, which is administered posteruptively in prolonged cures for the treatment of acne, periodontal disease, or rheumatoid arthritis, has been associated with tooth color pathology.1,5,11–13 Dental fluorosis is caused by the alteration of enamel formation due to an increased fluoride intake. It is characterized by white opaque or brown stains (due to the adsorption of

chromophore agents from the oral environment), and, in more severe cases, by lack of substance.11 Color changes due to aging Color changes due to aging are a complex, multifactorial transformation. Among the causes are the penetration of staining agents from the oral environment into the dental tissues, the thinning and the increasing translucency of the enamel layer, as well as the deposition of secondary and reparative dentin, which has an orange-brown shade. 8.1.2 Clinical examination A proper etiological diagnosis and a complex treatment plan require a detailed assessment of every patient, based on a thorough clinical and photographic investigation. The medical and dental history should include: • General disorders associated with tooth discoloration. • History of medication or mouth rinse responsible for dental discoloration. • History of dental discoloration: onset and progression (did it show at the time of tooth eruption, or subsequently). • Possibility of correlating color changes with certain events (trauma, dental treatments). • Information regarding diet and smoking. • Oral hygiene habits, whitening products (rinse solutions, whitening pastes, gels). • History of in-office or dentist-supervised whitening treatments. • Clinical or dental conditions that would contraindicate bleaching, or that are known to be less influenced by oxidative treatments. Information on the dental color self-perception and the patient’s own desire to improve the dental shade (what “whiter teeth” means in his/her opinion) should not be omitted. It has been suggested that it is not only important to increase the teeth lightness by a certain number of shade tabs, but also to gain a dental color that closely matches the color of the sclera – the white of the eyes.14 Esthetic questionnaires used for recording this information play an essential role in dentist-patient communication; furthermore, they may be documents with legal value. Data regarding dental color are gathered during the patient’s clinical examination. In addition to the protocol presented in Chapter II, the following questions regarding tooth

discoloration should also be answered: • What tooth, group of teeth, or dental arch is/are affected by discoloration? • What is the extension of the color change on the dental surface? • What is the dental shade (expressed in the Vita Classical or 3D Master coding system)? The shade color can be either visually or instrumentally recorded. • Is it a superficial, external staining or an inherent discoloration of the tooth structure? • Is it a uniform discoloration, or does it appear as colored or opaque bands, spots, or lines on the dental surface? • Are there any restorations (composite fillings, veneers, crowns), and what is their chromatic appearance in comparison with the natural dentition? Would the patient want them replaced after bleaching if they do not match the final dental color? In addition to the clinical data, dental photography is of paramount importance. In order to have a realistic and relevant image of the baseline, the tooth should be captured next to the samples of different shade guides, either classical (Vitapan Classical) or value-based (Vitapan 3D Master; Linearguide 3D Master). When bleaching treatments are envisaged, the Vita Bleachguide 3D Master shade guide is recommended, which is especially designed for monitoring the efficacy of tooth whitening.15 It includes high-value shade tabs. In addition, the distribution of the samples in the color space is uniform, and, on account of this, the results of whitening may be better quantified (Fig 8-5). Single-tooth and panoramic radiographs should be obtained in order to prevent overlooking the pathology responsible for dental discoloration. In some cases, color or translucency alteration is the only sign of teeth with pulp necrosis or calcific metamorphoses. Vitality tests are also indicated in these cases (see section 8.2).11,14 8.1.3 Treatment of tooth discoloration The medical approach to dental discoloration involves an integrative, complex treatment plan that addresses all the pathological conditions recorded during the clinical examination. Moreover, the improvement of the dental shade is often obtained through the combination of several treatment methods. When treatment planning is considered, it is absolutely necessary to know the etiology and the clinical form of discoloration (extrinsic, internalized, or intrinsic), the intensity and the shade of staining, its location to one or more teeth, as well as other conditions that may affect

the teeth: dental decays, fissures or fractures, and endodontic and restorative treatments (including their quality). Depending on the result of the examination, the treatment plan may include: • Prophylactic cleaning, and recommendations regarding at-home use of additional whitening products. • Microabrasion and macroabrasion. • Dental bleaching, with oxidative substances, in various protocols: – At-home, patient-managed bleaching with over-the-counter products. – Dentist-supervised bleaching with low-and medium-concentration peroxide-based products. – In-office sessions based on high-concentration substances (for vital and/or non-vital teeth). – Whitening methods specific for non-vital teeth. – Partial or full coverage with composite resins or ceramic veneers, metal-ceramic or ceramic crowns. 8.1.3.1 Prophylactic cleaning and whitening products recommended for oral hygiene Professional cleaning is aimed at removing bacterial plaque and calculus debris through scaling, followed by professional tooth brushing.7,16 Professional tooth brushing is a prophylactic method aimed at removing bacterial plaque and extrinsic staining. It is carried out with rotating instruments at low speed, using rubber cones for proximal spaces and rubber cups for vestibular and oral surfaces. It is combined with prophylactic fluoride and abrasive pastes,7,11,17 and with an air-flow projection of sodium bicarbonate particles onto the dental surface. Products aimed at lightening the teeth may be recommended during cleaning sessions. However, whitening toothpastes and mouth rinses are frequently used by patients without a specific indication or medical control.

Fig 8-5 Vita Bleachguide 3D Master shade guide.

There is a myriad of oral hygiene products used as adjuvants for tooth whitening, and whitening toothpastes can have different action mechanisms.11,12,14,16 Toothpastes with an abrasive mechanism are aimed at removing extrinsic pigmentation and inhibiting its subsequent deposition. Currently, the majority of toothpastes exhibit this mechanism, their abrasive effect depending on the size and concentration of abrasive particles.17 Active abrasive agents include carbonates, calcium phosphates and pyrophosphates, alumina, and sodium bicarbonate. The last one is considered an abrasive agent with small-size particles, which can address details of the dental surface successfully.11 An exaggerated abrasive effect can affect the thickness of the enamel layer and, in addition, induce a yellowish shade, due to the underlying dentin. Toothpastes with a chemical mechanism include those based on peroxides (hydrogen, calcium peroxides), sodium citrate, or sodium phosphates.17 Due to the short contact time of the pastes with the tooth surface, the whitening effects are limited.11,18 Toothpastes with an enzymatic mechanism, which contain the enzyme papain, are aimed at reducing the formation of bacterial plaque on the tooth surface. Cosmetic toothpastes based on an optical effect form a pellicle, which infiltrates the tooth surface details, inducing the perception of whiter teeth.11,17 The optical effect is based on substances that change tooth color perception from a yellow to a bluish shade (bluecovarine), or on titanium dioxide.11,17-19 In addition to toothpastes, mouth rinses of various compositions contribute to improving tooth color. Some peroxide-based products may be purchased directly by the patient and used during a patient-managed dental bleaching protocol. These products will be presented in section 8.1.3.3.

8.1.3.2 Microabrasion Microabrasion is recommended in the case of limited areas of discoloration that affect the superficial enamel structure (eg, dental fluorosis) through the combination of acids and abrasive pastes. Macroabrasion consists of removing the superficial, discolored enamel layer over a limited area using fine diamond or carbide burs. Another option for removing the stains is air abrasion, with fine abrasive particles. Microabrasion and macroabrasion should be regarded as intermediary methods between bleaching techniques and more invasive methods like veneers or crowns. In the case of over-reduction, the labial surface should be restored with dental composites. Fluoridation of the abraded surface is also recommended.11,14 8.1.3.3 Bleaching techniques Dental bleaching is recommended for the treatment of internalized and intrinsic tooth discoloration and is basically aimed at altering the optical parameters of dental structures by eliminating staining molecules. It is believed that chromophores become attached to hard dental tissues by two mechanisms: • Interaction with the organic component in the enamel and dentin (eg, polyphenols from tea bind through five hydroxyl groups to the organic substance), forming stable compounds.3,13,20 • Calcium ion chelation (eg, hydroquinone in tetracycline).1,12,13 The removal of organic chromophores from dental structures is based on oxidative mechanisms. The bleaching products that are currently in use are hydrogen peroxide, carbamide peroxide, and sodium perborate. Hydrogen peroxide diffuses through enamel and dentin. Under alkaline conditions, it acts as a strong oxidizing agent through the formation of free radicals, reactive oxygen molecules, and hydrogen peroxide anions.11,21,22 These compounds may cleave the double bonds that bind pigment molecules to the dental structure, or oxidize their chemical moieties, forming soluble molecules or less heavily pigmented constituents. These are believed to reflect less light, thus creating a whitening effect.1,3,12,13,16,21 However, new insights into the chemical affinity of hydrogen peroxide during its diffusion

through enamel and dentin indicate its oxidizing effect on the organic compounds of dentin,23 as well as enamel.21 According to Eimar et al, in addition to the effect of hydrogen peroxide on the chromophores, which are, as a result, modified into more translucent molecules reflecting less light, hydrogen peroxide also oxidizes the transparent organic matrix into a more opaque, whiter material. This might explain the variability of the bleaching results, which may be due to the differences of the enamel concentration in organic material among individuals, as well as the lower bleaching efficacy in the elderly, as a consequence of a lower protein content in the enamel.21 Hydrogen peroxide can be used directly in different concentrations, or is generated locally by the decomposition of an organic derivate, carbamide peroxide or urea peroxide (CH6N2O3). During the bleaching treatment, carbamide peroxide is decomposed into urea (CH4N2O) and hydrogen peroxide (H2O2). As described previously, hydrogen peroxide produces reactive oxygen species able to remove or oxidize a wide variety of organic or inorganic structures.11,21 Carbamide peroxide is contained in gels with different concentrations: • 10% (equivalent to 3.35% hydrogen peroxide). • 15% (equivalent to 5.4% hydrogen peroxide). • 20% (equivalent to 7% hydrogen peroxide). • 35% (equivalent to 10% hydrogen peroxide). Another oxidative precursor is sodium perborate, used for non-vital tooth whitening, in an endodontic application (see section 8.2). Indications for bleaching treatment • Vital or non-vital dischromic teeth, as the treatment of choice or in combination with subsequent prosthetic treatments. • Internalized and intrinsic discolorations, particularly in yellow, orange, and brown shades. • Patients in a good general health status, compliant, with adequate oral hygiene. Contraindications for bleaching treatment • Pregnant or lactating women. • Disease of the oral mucosa, a burning sensation that can indicate allergic reactions. • Severe discoloration requiring other treatment methods (veneers, crowns). In these situations, bleaching may be associated with prosthetic treatments. • Composite or ceramic restorations that are not to be replaced. The patient should be

informed that the restorations may not match the bleached teeth after treatment, since the dental materials do not respond in the same way to bleaching as the dental structures do.13,14,16,24 There are also situations that should be regarded as relative contraindications due to dischromic conditions with a poor prognosis to whitening procedures: • Gray or bluish shades are more difficult to remove by oxidizing treatment. • Teeth with a highly translucent aspect; bleaching may cause increased translucency that will be perceived as darker areas on the dental surface. • Saturated color in the gingival area or in the root portion is less responsive to bleaching due to differences in the dentinal structure in this zone.14 In addition, a cautious attitude is recommended in the case of reported dental sensitivity due to gingival recession, abrasion, cervical lesions (with dentinal exposure), or in children with a larger dental pulp, in order to reduce the risk of pulpal inflammation. At-home bleaching At-home bleaching is based on over-the-counter, peroxide-based products that can be used by patients with or without medical recommendation and control. The commercial forms and protocols of application differ, and usually depend on the desired whitening results. Adhesive strips containing 6% to 14% hydrogen peroxide have a configuration adapted for the maxillary and mandibular anterior teeth. The strips are recommended to be placed on the tooth surface for 30 minutes, once or twice a day.11,14,24 Peroxide-based gels, in combination with prefabricated trays, may cause lesions of the gingival fibromucosa due to the lack of intimate contact of the tray with the oral tissues, and the reflux of the whitening material. However, the most important inconvenience of the over-thecounter methods is the lack of medical supervision. In the case of the over-the-counter methods, the treatment is not administered following a clearly formulated diagnosis, which can mask symptoms of dental conditions that should be treated by other methods (dental decays, pulp necrosis, periapical lesions). In addition, the results of treatment are not professionally monitored, and the overdose of inadequate products or protocols can induce harmful side effects, such as enamel erosion and dentin sensitivity.1,11,14,24 Dentist-supervised bleaching

Dentist-supervised bleaching is done with low- and medium-concentration peroxide gels and custom-fitted trays. Bleaching is initiated in the dental office, following a comprehensive examination, and continued as a patient-managed treatment. This method involves the use of 10%, 15%, and 20% carbamide peroxide gels, or the more recently introduced 7.5% to 9.5% hydrogen peroxide gels, as well as custom-fitted trays that are fabricated on models. The following stages are involved: • Examination of the patient, according to the previously presented plan. The data gathered during the initial examination, the dental-color changes, and the bleaching materials and protocols used (including their side effects) could be synthetized onto a chart for each patient (Fig 8-6). • The initial color can be expressed by using as a reference the color coding of the shade guides, or the L*a*b* values recorded with instruments. Initial photos, with the shade guides in position, are also recommended. • Professional cleaning aims to remove plaque, calculus, and external pigmentations. If there are signs of sensitivity, the first bleaching session is postponed for several days.14 • Accurate impressions of the dental arches, with alginate or silicones (Figs 8-7 and 8-8). 8.1.3.4 Fabrication of models and trays using the thermoformation technique This technique involves the intimate fitting of a vacuum-formed tray material – usually a plastic polyethylene foil – on the surface of the previously prepared model. Depending on the indication, the trays may or may not include vestibular reservoirs for the whitening gel; in addition, they may have scalloped or non-scalloped gingival margins. The vestibular reservoir increases the amount of material in contact with the dental surface. Scalloped margins, parallel to the gingival margins at the cervical level, or 1 mm incisally/occlusally to it, have the advantage of reducing the contact of the peroxides with the gingiva. Scalloping is recommended in the case of fragile gingival tissues, or when highly concentrated peroxides or less-fluid bleaching gels are to be used.14 This marginal configuration reduces the gel reflux capacity, as well as the risk of gingival lesions.

Fig 8-6 Chart for dental bleaching.

Fig 8-7 Alginate impressions of the dental arches for the construction of trays.

Fig 8-8 Stone models.

Fig 8-9 a, b Construction of facial reservoirs.

Fig 8-10 The thermoformed tray on the model.

Fig 8-11 Marginal fitting of the thermoformed tray.

The space for the reservoir is created on the model by covering the vestibular surface of the teeth with a light-polymerized resin. This aims to generate a 0.5 to 1 mm space for the reservoir. For an adequate marginal sealing, the resin is applied at a distance of 1 mm

minimum from the marginal gingiva (Figs 8-9a, 8-9b, and 8-10). During thermoformation, folds or wrinkles of the plastic foil should be avoided; once plastified, the tray should be in intimate contact with the model. Marginal fitting is achieved by trimming with scissors or a scalpel (Fig 8-11). In the next session, the custom tray is verified in the oral cavity. In order to prevent muscular symptoms, the occlusal contacts should not be influenced by the tray.14 The margins should be smooth in order to be comfortable for the soft tissues. A small amount of 10% to 15% carbamide peroxide gel is applied into the deep area of the tray, corresponding to the labial or buccal surface (Fig 8-12). After the tray is correctly positioned on the previously dried dental arch, the excess gel flowing towards the gingiva is removed using a cotton pad. The patient should be given indications regarding: • Wearing time – depending on the concentration of the active substance, 3 to 8 hours, during the daytime or overnight. • After removal, the trays should be cleaned and the dental arches rinsed. Dental brushing should be avoided immediately after the removal of the tray, and so should carbonated, acidic beverages.

Fig 8-12 Loading the tray.

• Foods and beverages with a staining effect, as well as smoking, should also be avoided during treatment. • Patients should be instructed to report any adverse reactions that may appear during bleaching: – Dental sensitivity or pain. – Painful lesions of the oral mucosa.

– Other local or general symptoms. The number of sessions is established according to the bleaching results; most frequently, 8 to 14 applications are advisable with 10% to 15% carbamide peroxide. The patient should be aware that the most noticeable results are obtained after the first sessions, and that the subsequent color changes are slower. In the case of intrinsic discoloration of specific etiology, other sessions can be planned. The dental color is assessed again at least during the final appointment, where the final photos with shade guides will illustrate the difference in color from the initial consultation (Figs 8-13a and 8-13b). Adjuvants of enamel remineralization are also recommended. After 2 to 3 weeks, any composite fillings or other restorations that do not match in color with the whitened teeth are changed, where necessary. This is planned at the preliminary appointment.1,11,24 The advantages of dentist-supervised bleaching treatments are: • The whitening effect of gels with a low or medium carbamide peroxide concentration is comparable to the results obtained from in-office treatments, or even better.14,25,26 In fact, there is a limit up to which brightness can be increased, or the red and yellow color saturation reduced (increase of L*, decrease in a* and b* CIE L*a*b* color coordinates).20,24 • Low and medium carbamide or hydrogen peroxide concentrations are less likely to induce structural defects of the enamel; further application of fluoride gels and products containing nanohydroxyapatite or caseinphosphopeptide-amorphous calcium phosphate (CPP-CP) stimulate remineralization.11,20,27,28 • Custom trays maintain the gel in contact with hard dental tissues and reduce the risk of its diffusion towards the oral cavity, as well as the risk of mechanical irritation. • The mechanism of the slow release of peroxides increases the tolerance of products, reducing the risk of side effects.11,20 • Comprehensive initial examinations and follow-ups allow for the monitoring of color changes and possible side effects. Dentist supervision avoids the risk of using oxidative products outside the clinical indications, or in excess.29,30 Disadvantages of this method relate to the longer period of time required for expected whitening results compared to the in-office method.

Fig 8-13 Dentist-supervised bleaching: a. Before. b. After whitening treatment.

Fig 8-14 Isolation of soft tissues.

Fig 8-15 Lamp position in relation to vestibular surfaces.

In-office bleaching Two variants are commonly used for in-office bleaching: • High concentration (35%) carbamide peroxide gels, in trays, with a recommended wearing time reduced to 15 minutes. These methods can be used, with precautions, as at-home applications. Other products, based on hydrogen peroxides at 7.5% to 9.5%, have been more recently introduced.14 • In-office application of hydrogen peroxide solutions or gels (35%), painted directly on the dental surface, with or without thermo- or light activation. This method requires proper isolation of the oral mucosa and surrounding soft tissues with a rubber dam, or with the light-polymerized resins available in the peroxide kits (liquid rubber dam) (Fig 8-14). The latter method of isolation has been recommended when a limited number of teeth are to be bleached.14 Following isolation, the gel or liquid oxidative product is applied on the dental surfaces.24 In the case of the light-assisted method, either a conventional light-curing lamp or other specialized equipment is used.14 The active portion should be placed at 5 to 10 cm from the tooth surface (Fig 8-15). The total exposure time and the number of applications vary in relation to the initial shade – 20 to 30 minutes for homogeneous pigmentation, and 5 to 10 minutes, with repeated applications, in the case of nonhomogeneous stains (Fig 8-16).24 One or more appointments are recommended in order to get the desired result. An average of three sessions is usually the protocol of choice,14 although the decision should take into account not only the whitening results but also the side effects. The role of light-assisted methods is controversial. It is accepted that light increases the

local temperature and thereby stimulates the decomposition rate of hydrogen peroxide. This, in turn, accelerates the release of oxygen-whitening radicals and influences, to a certain extent, the permeability of dental structures and the consequent diffusion of these molecules.14 However, the risk of dental sensitivity as a consequence of pulp inflammation due to the increased temperature is documented in the literature.14,31,32

Fig 8-16 Application of the whitening gel on the facial surface.

Fig 8-17 In-office bleaching: a. Initial. b. After in-office session.

Lasers may be used as activating light sources (argon lasers, CO2 lasers, diode lasers). The mechanism is the same: lasers with various wavelengths and spectral powers provide the energy to release the oxygen more rapidly, thereby increasing the efficiency of the whitening method per time unit.32,33 The advantages of the in-office method basically relate to the shorter time required for whitening (Figs 8-17a and 8-17b). Higher peroxide concentrations require shorter contact time. However, when the final results of bleaching protocols are compared, the lowerconcentration products used in at-home protocols provide similar, or even enhanced, more stable, whitening results.14 The disadvantages of the in-office methods include tooth sensitivity or pain due to pulp response to the increased temperature and the chemical effects of peroxides. The symptoms are relieved in the majority of cases, after the cessation of exposure. Other side effects consist of a white, chalky appearance of the dental surface. It is recognized that in this variant of treatment, a portion of the whitening effect is temporary and is a consequence of dehydration; the final color develops with subsequent darkening due to rehydration (Fig 8-18).14 The chemical effect on soft tissues, due to improper isolation, may vary from mild irritation to severe ulceration of the gingival, labial, or buccal mucosa. 8.1.3.5 Side effects of oxidative bleaching The treatment of tooth discoloration by bleaching is considered a minimally invasive method since the integrity of the dental structure is maintained. However, its widespread use, often without medical indication or supervision, is accompanied by a number of risks. The literature

abounds with studies focused on the evaluation of the side effects of materials and techniques used to treat the chemical discoloration of tooth structures. Apart from focusing on the systemic effects, these studies evaluate the side effects on hard dental tissues (enamel, dentin), and on dental pulp and oral mucosa (Fig 8-19).

Fig 8-18 White chalky appearance immediately after whitening.

Fig 8-19 Reversible soft-tissue lesions right after the whitening treatment.

8.1.3.6 Side effects on mineralized tissues The following side effects on enamel and dentin have been considered: • Changes of the enamel texture, investigated by scanning electron microscopy, atomic force microscopy, nanoindentation, or profilometry techniques. • Variation in the enamel and dentin microhardness and the influence of treatment on the calcium and phosphate concentration in dental tissues (evaluated with spectrophotometry or photometric assessment).33–45

The conclusions of studies are often controversial. Their results vary according to several factors, including: • The experimental material (based on hydrogen peroxide or carbamide peroxide). • Concentration of active ingredients. • pH level. • Exposure time. • Study protocol (in vitro using human or bovine enamel, or dentin samples, or extracted teeth). • Studies performed in situ or in vivo. It has been concluded that the use of carbamide peroxide has less aggressive effects on the hard structures in comparison with the use of high concentrated hydrogen peroxide. A low carbamide peroxide concentration (10% to 15%) produces no changes on the enamel surface.34–36 The daily exposure to 10% carbamide peroxide for up to 5 weeks is considered a safe, conservative, and effective procedure.14,29,34-36 However, there are studies that have reported significant microhardness loss and morphological changes of the enamel due to 35% hydrogen peroxide application.28,46 The enamel remineralization is favored by the saliva.23 The addition of fluoride ions into the bleaching products or as a consecutive application has been reported to decrease the rate of demineralization and to help enamel remineralization.28,3740 More recently, due to concerns related to fluoride efficiency (low solubility, which allows for the deposition of fluorapatite in the superficial layer and less in the deeper enamel),47 other calcium and phosphate-based substances, such as caseinphosphopeptide-amorphous calcium phosphate (CPP-CP), nanohydroxyapatite, or Bioglass (based on SiO2, Na2O, CaO, and P2O5), have been introduced as alternatives to reestablish the enamel texture after dental bleaching.27,28 The essential role of the pH of bleaching products has also been emphasized. Acid pH seems to be even more harmful on the enamel surface than the increased concentration of peroxides in the whitening material.41 However, due to their urea-releasing effect, carbamide peroxide-based gels maintain the pH in the alkaline range. As such, studies have aimed at neutralizing the pH of the products intended for these treatments.42-45

Tooth sensitivity Tooth sensitivity is the most frequent side effect reported by the literature,14 its intensity varying from mild discomfort to pain.48–50 It is caused by the penetration of peroxides to the pulp, promoting the release of inflammatory modulators,51 and is, in most cases, reversible. In previously restored teeth, this phenomenon is even more likely to occur.52 Two possible approaches to tooth sensitivity exist: the passive and the active. In the first instance, the aim is to change the bleaching protocols by reducing the duration of exposure, the frequency of treatment sessions, or the concentration of peroxides.12,24,26,29 The second approach consists of the addition, during or after the bleaching session, of active substances aimed at reducing the symptoms. Fluoride gels may be used, which act by blocking the dentinal tubules and reducing the fluid flow to the pulp.14 Alternatively, pastes with potassium nitrate used by tooth-brushing or in trays may be applied. The latter is believed to act by chemical depolarization of nerve endings and by releasing nitric oxide radicals, which diminish painful sensations.12,24 This causes an anesthetic effect on the sensitive teeth. Dental bleaching in the case of cervical lesions, erosions, extensive restorations, enamel fissures, or reported sensitivity requires special attention due to the increased risk of further dental hypersensitivity.14,50,53 Effects on the oral mucosa The adverse effects on the gingiva and oral mucosa are often caused by mechanical irritation due to ill-fitted trays. Custom-fitted trays, based on an accurate impression, reduce this risk. In addition, custom-fitted trays maintain the peroxide gel in close contact with the tooth surface, decreasing the risk of peroxide-gel diffusion towards gingival tissues.49,50,53,54 In the case of in-office bleaching, gingival protection is mandatory. Anesthesia is contraindicated; on the contrary, continuous assessment of dental and gingival sensitivity is important in order to prevent irreversible reactions of the pulp, or the bleaching gel coming into contact with the soft tissues.11,14 In the case of tissue burns, rehydration of the mucosa and an antiseptic ointment relieve the symptoms. Effects on the restorations The major concern is the inhibition of the bonding capacity of adhesive systems due to increased residual oxygen in the enamel or dentin. To avoid this, adhesive restorations (composites, resin-bonded ceramic veneers, or crowns) will be scheduled 2 to 3 weeks after the completion of peroxide treatment. This time interval is needed to allow for the stabilization

of dental color changes.14 Esthetic restorations may also require replacement, since their color is not altered by the whitening material. Other side effects of bleaching materials include dysphagia, digestive conditions due to glycerin, and temporomandibular joint discomfort, caused by the wearing of trays. There are in vitro studies that certify the mutagenic effect of carbamide peroxide, but the results have not been validated in vivo; however, it is recommended that risk factors be avoided (eg, smoking) during the whitening treatment.3,55,56 Whitening treatment should be avoided during pregnancy and lactation.11,13,14 8.1.4 Conclusions In conclusion, dental bleaching using oxidative methods is a treatment that is being more frequently requested in dental offices due to the increasing interest of patients in the esthetic field of dentistry. The large spectrum of currently available products offering treatment solutions for dischromic conditions permit dental color improvement by reducing tooth saturation and increasing brightness.

Fig 8-20 a. Discoloration of the central incisor. b. Full ceramic crown. c. Final view.

Although these methods can offer a specific solution to both the patient and the dentist, they should be considered as part of a comprehensive treatment plan, based on a thorough examination and diagnosis. In this way, the risks of side effects can be reduced, and the results professionally monitored. When dental bleaching is planned, it should be taken into consideration that the tray method, in combination with 10% peroxide carbamide, is the safest and best-documented treatment available.14 Recent studies demonstrate that treatment using a low concentration of carbamide peroxide agents has been similarly effective after a treatment period using mediumconcentrated gel (16%). Practitioners must be knowledgeable about bleaching techniques in order to provide an evidence-based choice for their patients.25,26 In-office methods, based on a higher concentration of carbamide peroxides and hydrogen peroxides, are recognized to induce adverse effects on mineralized and soft tissues; their advantage is only related to a shorter treatment time. Patients should be informed that the

bleaching result of the tray method, with lower-concentration products, provides a better outcome.14 The combination of an in-office method with consecutive treatments of at-home bleaching is a common procedure. Over-the-counter products, based on oxidative or non-oxidative treatments, are less predictable in respect of their efficiency and side effects, mostly due to the lack of examination and professional indications. On the other hand, the combination of chemical and prosthetic methods is frequently indicated. Bleaching can be performed, depending on the clinical situation, as external whitening (dentist-monitored, in-office methods), or as internal bleaching. However, severe discolorations cannot be resolved solely by chemical treatments and require composite or ceramic restorations. Regarding both laminate veneers and ceramic crowns, the ceramic material translucency should be correctly selected in order to avoid a dark underlying layer showing through. In the case of important color changes, the first requirement is to mask tooth discoloration, usually by means of opaque layers or copings (Figs 8-20a to 8-20c). These aspects are detailed in Chapter IX.

REFERENCES 1. Goldstein RE. Esthetics in Dentistry, vol 1, ed 2. Hamilton: BC Decker, 1998. 2. Dudea D, Badea M, Sava S, Manole M. Tratamentul discromiilor dentare prin procedee oxidative. Clujul Medical 2004;2:358–365. 3. Watts A, Addy M. Tooth discoloration and staining: A review of the literature. Br Dent J 2001;190:309–316. 4. Nathoo SA. The chemistry and mechanisms of extrinsic and intrinsic discoloration. J Am Dent Assoc 1997;128(suppl):6S–10S. 5. Joiner A. The bleaching of teeth. A review of the literature. J Dent 2006;34:412–419. 6. Proctor GB, Pramanik R, Carpenter GH, Rees GD. Salivary proteins interact with dietary constituents to modulate tooth staining. J Dent Res 2005;84:73–78. 7. Lindhe J. Textbook of Clinical Periodontology, ed 2. Copenhagen: Munksgaard, 1992. 8. Addy M, Sharif N, Moran J. A non-staining chlorhexidine mouthwash? Probably not: A study in vitro. Int J Dent Hygiene 2005;3:59–63. 9. Claydon NCA, Addy M, Adams G, et al. A comparison of two chlorhexidine gel brushing regimens and a conventional toothpaste brushing regimen for the development of tooth staining over a 6-week period. Int J Dent Hygiene 2006;4:183–188. 10. West NX, Addy M, Macdonald E, Chapman A, Davies M, Moran J, Claydon N. A randomised crossover trial to compare the potential of stannous fluoride and essential oil mouth rinses to induce tooth and tongue staining. Clin Oral Invest 2012:16:821–882. 11. Greenwall L. Bleaching Techniques in Restorative Dentistry. London: Martin Dunitz, 2001. 12. Sheen S, Banfield N, Addy M. The effect of unstimulated and stimulated whole saliva on extrinsic staining in vitro: A developmental method. J Dent 2002; 30:365–369. 13. Touati B, Nathonson D, Miara P. Esthetic Dentistry and Ceramic Restoration. London: Martin Dunitz, 1999. 14. Hilton TJ, Ferracane JL, Broome J. Fundamentals of Operative Dentistry. A Contemporary approach, ed 4. Chicago: Quintessence, 2013. 15. Paravina RD, Johnston WM, Powers JM. New shade guide for evaluation of tooth whitening: Colorimetric study. J Esthet Restor Dent 2007;19:276–283. 16. Dale BG, Aschheim KW. Esthetic Dentistry. A Clinical Approach to Techniques and Materials. Philadelphia: Lea and Febiger, 1993. 17. Joiner A. Whitening toothpastes: A review of the literature. J Dent 2010;38S:e17–e24. 18. Bowles WH, Frzsh H, Baker FL, Browning J. Preliminary in vitro evaluation of tooth lightening prophylaxis paste. J Esthet Dent 1997;9:234–235. 19. Collins LZ, Naeeni M, Platten SM. Instant tooth whitening from a silica toothpaste containing blue covarine. J Dent 2008;36(suppl 1):21–25. 20. Sullieman M, Addy M, Mac Donald E, Rees JS. The effect of hydrogen peroxide concentration on the outcome of tooth whitening: An in vitro study. J Dent 2004; 32:295–299. 21. Eimar H, Siciliano R, Abdallah MN, et al. Hydrogen peroxide whitens teeth by oxidizing the organic structure. J Dent 2012;40(suppl 2):e25–e33. 22. Goldberg M, Grootveld M, Lynch E. Undesirable and adverse effects of tooth-whitening products: A review.

Clin Oral Invest 2010;14:1–10. 23. Ubaldini AML, Baesso ML, Neto AM, Sato F, Bento AC, Pascotto RC. Hydrogen peroxide diffusion dynamics in dental tissues. Dent Res 2013;92:661–665. 24. Goldstein RE, Garber DA. Complete Dental Bleaching. Chicago: Quintessence, 1995. 25. Meireles SS, Fontes ST, Coimbra LAA, Della Bonna A, Demarco FF. Effectiveness of different carbamide peroxide concentrations used for tooth bleaching: An in vitro study. J Appl Oral Sci 2012;20:186–191. 26. Soares DG, Basso FG, Pontes ECV, Garcia LFR, Hebling J, de Souza Costa CA. Effective tooth-bleaching protocols capable of reducing H2O2 diffusion through enamel and dentine. J Dent 2014;42:351–358. 27. De Vasconcelos AAM, Cunha AGG, Borges BCD, et al. Enamel properties after tooth bleaching with hydrogen/carbamide peroxides in association with a CPP-ACP paste. Acta Odontol Scand 2012;70:337–343. 28. Deng M, Wen HL, Dong XL, et al. Effects of 45S5 bioglass on surface properties of dental enamel subjected to 35% hydrogen peroxide. Int J Oral Sci 2013;5:103–110. 29. Haywood VB, Leonard RH, Nelson CF, Brunson WD. Effectiveness, side effects and long-term status of nightguard vital bleaching. J Am Dent Assoc 1994;125:1219–1226. 30. Heymann HO, Swift EJ, Bayne SC. Clinical evaluation of two carbamide peroxide tooth-whitening agents. Compend Contin Educ Dent 1998;19:359–362. 31. Nash RW. In-office bleaching system for quick esthetic change. Compend Contin Educ Dent 1999;20:986– 990. 32. Buchalla W, Attin T. External bleaching therapy with activation by heat, light or laser: A systematic review. Dent Mater 2007;23:586–596. 33. Anaraki SN, Shahabi S, Chiniforush N, Nokhbatolfoghahaei H, Assadian H, Yousefi B. Evaluation of the effects of conventional versus laser bleaching techniques on enamel microroughness. Lasers Med Sci, 2014, DOI: 10.1007/s10103-014-1523-6. 34. Dudea D, Florea A, Mihu C, Campianu R, Nicola C, Benga GH. The use of scanning electron microscopy in evaluating the effect of a bleaching agent on the enamel surface. Rom J Morphol Embry 2009;50:435–440. 35. Basting RT, Junior R, Serra MC. The effect of 10% carbamide peroxide bleaching materials on microhardness of sound and demineralized enamel and dentin in situ. Oper Dent 2001;26:531–539. 36. Kelleher MGD, Roe FJC. The safety-in-use of 10% carbamide peroxide (Opalescence) for bleaching teeth under the supervision of a dentist. Brit Dent J 1999;187:190–199. 37. de Freitas PM, Basting RT, Rodrigues JA, Serra MC. Effects of two 10% peroxide carbamide bleaching agents on dentin microhardness at different time intervals. Quintessence Int 2002;33:370–375. 38. White DJ, Featherstone JD. A longitudinal microhardness analyses of fluoride dentifrice effects on lesion progression in vitro. Caries Res 1987;21:502–512. 39. Lewinstein I, Fuhrer N, Churaru N, Cardash H. Effect of different peroxide bleaching regimens and subsequent fluoridation on the hardness of human enamel and dentin. J Prosthet Dent 2004;92:337–342. 40. Justino LM, Tames D. In situ and in vitro effects of bleaching with carbamide peroxide on human enamel. Oper Dent 2004;29:219–225. 41. Joiner A. Review of the effects of peroxide on enamel and dentine properties. J Dent 2007;35:889–896. 42. Pinheiro Junior EC, Fidel RA, Cruz Filho AM, Silva RG, Pecora JD. In vitro action of various carbamide peroxide gel bleaching agents on the microhardness of human enamel. Braz Dent J 1996;7:75–79. 43. Cavalli V, Arrais CAG, Giannini M, Ambrosano GMB. High-concentrated carbamide peroxide bleaching agents

effects on enamel surface. J Oral Rehab 2004;31:155–159. 44. Clark DM, Hintz J. Case report: In-office tooth whitening procedure with 35% carbamide peroxide evaluated by the Minolta CR-321 Chroma Meter. J Esthet Dent 1998;10:37–42. 45. Cakir FY, Korkmaz Y, Firat E, Oztas SS, Gurgan S. Chemical analysis of enamel and dentin following the application of three different at-home bleaching systems. Oper Dent 2011;36:529–536. 46. Severcan F, Gokduman K, Dogan A, Bolay S, Gokalp S. Effects of in-office and at-home bleaching on human enamel and dentin: An in vitro application of Fourier transform infrared study. Appl Spectrosc 2008;62:1274– 1279. 47. Tschoppe P, Neumann K, Mueller J, Kielbassa AM. Effect of fluoridated bleaching gels on remineralization of predemineralized bovine enamel in vitro. J Dent 2009;37:156–162. 48. Jorgensen RG, Carroll WB. Incidence of tooth sensitivity after home whitening treatment. J Am Dent Assoc 2002;133:1076–1082. 49. Li Y. The safety of peroxide-containing at-home tooth whiteners. Compend Contin Educ Dent 2003;24:384– 389. 50. Powers JM, Sakaguchi RL. Craig’s Restorative Dental Materials, ed 12. St Louis: Mosby Elsevier, 2006. 51. Caviedes-Bucheli J, Ariza-Garcıa G, Restrepo-Mendez S, Rios-Osorio N, Lombana N, Munoz HR. The effect of tooth bleaching on substance P expression in human dental pulp. J Endod 2008;34:1462–1465. 52. Bonafe E, Bacovis CL, Iensen S, Loguercio AD, Alessandra Reis, Kossatz S. Tooth sensitivity and efficacy of in-office bleaching in restored teeth. J Dent 2013;41:363–369. 53. Schmalz G, Arenholt-Bindslev D. Biocompatibility of Dental Materials. Berlin: Springer, 2009. 54. Dahl J, Pallesen V. Tooth bleaching: A critical reviewing of the biological aspects. Crit Rev Oral Biol Med 2003;14:292–304. 55. Leonard RH Jr, Garland GE. Safety issues when using a 16% carbamide peroxide whitening solution. J Esthet Restor Dent 2002;14:358–367. 56. Goldstein RE. Esthetics in Dentistry, vol 2, ed 2. Hamilton: BC Decker, 2002.

8.2 NON-VITAL TOOTH DISCOLORATION Tooth discoloration is characterized by the etiology, appearance, location, severity, and affinity to the dental structure.1 Any change in the enamel, dentin, or pulp structure may cause alterations of optical dental properties related to light transmission. The etiological classification of teeth discolorations includes extrinsic, intrinsic, and a combination of these two types of discoloration.2 From an etiopathogenic point of view, non-vital tooth discoloration is part of an intrinsic discoloration of local etiology and is considered to be induced either by a number of pathological changes occurring in the dental tissues, or by the following consequences of root canal treatment:3 • Intrapulpal hemorrhage. • Pulp necrosis. • Root resorption. • Dental pulp fragments left unremoved during pulpectomy. • Root canal obturation materials. • Root canal filling materials. 8.2.1 Etiological classification of teeth discolorations 8.2.1.1 Discoloration caused by intrapulpal hemorrhage Intrapulpal hemorrhage can be induced by a tooth crown trauma severe enough to cause the breaking of pulp blood vessels. The infiltration of blood components into the dentinal tubules results in a discoloration of the adjacent dentin and the rapid subsequent temporary partial or total staining of the crown. The color of this staining is a shade of pink. The hemolysis of red blood cells that occurs causes the release of hema. This is a chemical compound that consists of a heterocyclic organic ring called a porphyrin ring, which contains an iron ion in its center. Hema is a component of hemoglobin, the well-known hemoprotein included in the red blood cells. Once released, hema combines with elements present in the necrotic pulp tissue, forming iron. This can, in turn, react with bacteria-produced sulfates, leading to the formation of dark colored ferric sulfates, which penetrate the dentinal tubules and cause a gray discoloration.4

It should be noted that iron release from the porphyrin ring is only possible in the presence of chemical products resulting from bacterial activity, as is pulp necrosis in septic conditions, ie, pulp gangrene. 8.2.1.2 Discoloration caused by pulp gangrene In the case of the diagnosis of pulp gangrene, the products resulting from fermentation and putrefaction processes that take place in the affected pulp tissue can penetrate the dentinal tubules, causing a discoloration whereby the degree of intensity is directly proportional to the time period elapsed from the onset of those chemical processes.5 8.2.1.3 Discoloration caused by tooth root resorption Tooth root resorption may sometimes be clinically visible as a pink area at the cementoenamel junction (CEJ). The so-called multiple idiopathic cervical root resorption (MICRR), with a higher frequency in young female subjects, can be both clinically and radiologically diagnosed and may cause the same discoloration feature.6 This type of cervical root resorption has been found to occur both in vital and non-vital teeth, and may progress, involving the whole pericervical area, or may spontaneously stop evolving.7 8.2.1.4 Discoloration caused by pulp fragments left unremoved after endodontic treatment Pulp fragments left in the pulp chamber may cause discoloration through the same mechanisms that occur following intrapulpal hemorrhage. The presence of pulp tissue remnants is likely due to an incorrect access cavity. 8.2.1.5 Discoloration caused by endodontic materials The sealer, root canal filling material, and residues of endodontic medication left in the pulp chamber following root canal treatment are in direct and permanent contact with the dentinal walls of the pulp chamber. The gradual impregnation of dentin may cause long-term tooth discoloration, frequently encompassing the whole crown.8,9 The prognosis of a whitening treatment depends on the type of endodontic materials that were used, and on the duration of their contact with dentin.

8.2.1.6 Discoloration caused by restorative materials Marginal microleakage occurring around old composite restorations leads to a discoloration initially located in these areas, which in time may gradually extend. The presence of amalgam restorations is frequently the cause of discolorations characterized by a dark gray shade, induced by oxidative processes due to the release of metal ions. The same may occur when using pin-retained restorations. 8.2.2 Therapeutic methods for non-vital tooth whitening The whitening materials used for the specific treatment of tooth discoloration are based on oxidation agents. These act on the organic structures present in hard dental tissues as dark large-size molecules, which slowly split into chemical compounds with smaller-size molecules and lighter shades. The oxidation-reduction reaction that occurs in this way is known as a redox reaction.10 The whitening agents used for the treatment of non-vital tooth discoloration are hydrogen peroxide, carbamide peroxide, and sodium perborate. Peroxides, both organic and inorganic, are strong oxidants and derive from hydrogen peroxide by the replacement of hydrogen atoms with metals (inorganic peroxides) or organic radicals (organic peroxides). Hydrogen peroxide is the active substance, which is contained in the whitening material as such, or is the result of a chemical reaction of decomposition that takes place in carbamide peroxide or sodium perborate-containing whitening products.10 Sodium perborate (Fig 8-21) is the whitening agent used by the non-vital tooth whitening procedure, applied as a treatment of choice in the case of discoloration localized to non-vital teeth. Sodium perborate is a white powder that is stable in a dry environment and easily decomposes (in the presence of water, acids, or hot air) to sodium metaborate, hydrogen peroxide, and oxygen.10 Before the application of any whitening technique to non-vital teeth, a very careful assessment of the endodontic treatment is required. The sealing of a three-dimensional root canal filling is essential in order to avoid undesired side effects such as external cervical root resorption, which may occur within a certain time period from the completion of treatment. The therapeutic approach for non-vital tooth whitening relies on the walking bleach technique and the simultaneous internal and external bleaching technique. The thermocatalytic method is no longer used due to the high risk of external cervical resorption.

8.2.2.1 The walking bleach technique The walking bleach technique is the technique of choice used for internal (intracoronal) whitening of non-vital teeth. First, the quality of endodontic treatment is radiologically evaluated; if this is inadequate, retreatment has to be performed before the initiation of the whitening procedures. As in the case of vital tooth bleaching, the tooth color is first assessed, and a photograph of the tooth and the shade guide element corresponding to the initial situation is taken. A rubber dam is placed, the restoration that has filled the cavity access is removed, any restorative materials present in the pulp chamber are also removed (restorations, liners, sealers, or root canal filling remnants), and 2 mm of the root canal filling apical of the CEJ is removed.

Fig 8-21 Sodium perborate tetrahydrate vial.

A glass-ionomer cement layer at least 2 mm thick is placed at this level, covering the root canal and filling up to the epithelial insertion. The coronal height of this barrier must be sufficient to avoid the infiltration of bleaching material along the dentinal tubules, preventing the possibility of external cervical (root) resorption. An extemporaneous mixture of sodium perborate and distilled water or saline solution is prepared, until a consistency similar to that of wet sand is obtained. The mixture of sodium perborate and hydrogen peroxide has a more rapid bleaching effect, but long-term results are similar, which does not justify the increased risk of tooth root resorption that occurs in this situation. The obtained mixture is applied in the pulp chamber and is compressed with a dry pellet, which allows for the absorption of the excess fluid, and the mixture is forced (preferably with a plastic instrument) into all the interstices of the pulp chamber. The excess is removed and a space of at least 2 mm is reserved for the temporary coronal restoration. A

temporary coronal restoration is performed, which is applied in direct contact with the mixture containing sodium perborate, by using a material that allows sealing, preferably glass-ionomer cement, in a sufficiently thick layer (minimum 2 mm). The patient is recalled for an evaluation of the result after 7 days, a time period considered to be optimal. If the result obtained is satisfactory, the temporary coronal filling and the sodium perborate mixture placed in the pulp chamber during the first session are completely removed, and a long-term restoration is placed. If the bleaching effect is insufficient, all the procedures performed in the previous session can be repeated, the patient being recalled after another 7 days. This therapeutic procedure should not be repeated more than three times, otherwise the risk of tooth root resorption increases significantly. Finally, under isolation conditions, the coronal restoration and the bleaching mixture are removed from the pulp chamber, and the long-term coronal restoration is made from composite material, overlying the glass-ionomer cement layer applied during the first treatment session. Following the application of this therapeutic method, the patient’s evolution should be examined, including a radiograph examination, every 6 to 12 months. Most cervical resorptions occur within a time period ranging between 6 months and 1 year, implying a follow-up of the clinical condition for at least 2 years after the completion of treatment. Advantages • The technique may yield rapid results, with only one or two treatment sessions being necessary. • Comfort for the patient, who will have normal mastication because between the treatment sessions the cavity is sealed with a long-term restoration material. • The wearing of a tray is unnecessary. Disadvantages • There is always a risk of cervical resorption. • Sometimes, whitening is obtained to a smaller extent at the cervical level, where discoloration usually manifests most prominently, due to the glass-ionomer cement barrier placed at this level in order to prevent cervical resorption. A variant of this method consists of using a 35% to 40% hydrogen peroxide gel (Fig 8-22), which is applied, under isolation, in the pulp chamber and prepared according to the

description above. The mechanism of cervical resorption is not perfectly understood. It is supposed that oxidants permeate the dentinal tubules of the cervical region, inducing root cement necrosis, periodontal ligament inflammation, and, finally, cervical resorption.

Fig 8-22 Opalescence Endo.

Fig 8-23 Opalescence Boost.

Fig 8-24 Opalescence Boost – self-activation.

8.2.2.2 The simultaneous internal and external bleaching technique This method involves the same stages presented in the walking bleach technique, up to the stage involving the placement of a 2 mm-thick layer of glass ionomer over the root canal filling.

A hydrogen peroxide whitening gel is then applied, both inside the pulp chamber and on the buccal surface of the tooth (Fig 8-23). If the whitening material is self-activating, it is left to act over the length of time specified by the manufacturer (Fig 8-24). A variant of this method involves the construction of a vinyl tray, according to the technique specified for vital tooth whitening, which has a buccal microreservoir at the level of the nonvital tooth affected by the discoloration (Fig 8-25). The patient applies a 10%, 15% or 20% carbamide peroxide bleaching gel at home, in the tray provided by the dentist, after completing the aforementioned clinical stages during the inoffice session, up to the placement of the glass-ionomer cement barrier. This allows for a several-day oral opening of the pulp chamber. During the wearing of the tray, the gel is simultaneously present in the pulp chamber and on the buccal surface of the tooth. Treatment, which begins as an initial in-office session, continues at home with the patient wearing the tray in the same way as for the treatment of vital tooth discoloration (home bleaching). After a number of days, depending on the results obtained, the stages described for the internal walking bleach technique are applied in the dental office. An advantage of this variant is that simultaneous internal and external whitening takes place, which can be effective despite the fact that much less aggressive bleaching substances are used. Furthermore, the risk of tooth cervical resorption is diminished. Current bleaching methods may be combined and, at the same time, use can be made of other means aimed at treating tooth discoloration: enamel microabrasion or restoration techniques, such as direct composite laminate veneers or porcelain laminate veneers. As a general rule, when the treatment of tooth discoloration must be continued using other therapeutic methods, such treatments have to be delayed for at least 2 weeks (even a month according to some authors) following the whitening treatment, for two reasons: • The final color obtained following bleaching takes several days to stabilize, the shade usually becoming slightly darker than the initially obtained color; the color also depends on the degree of rehydration of the dental tissues that follows the dehydration that first occured during the bleaching process.

Fig 8-25 Tray with a buccal microreservoir.

Fig 8-26 a Non-vital tooth 11 – preoperative view.

Fig 8-26 b Non-vital tooth 11 – postoperative view.

• Residual hydrogen peroxide left in the dental tissues prevents the effective adhesion of esthetic restorations or the resin luting cements used for porcelain laminate veneers. Whitening methods have no effect on preexisting esthetic restorations. Their shade may become too dark in relation to the tooth appearance achieved following the application of a

whitening method. Thus, the replacement of old esthetic restorations with new ones that correspond to the new chromatic appearance of the tooth crown following whitening treatment becomes necessary.

REFERENCES 1. Dahl JE, Pallesen U. Tooth bleaching: A critical review of the biological aspects. Crit Rev Oral Biol Med 2003;14:292–304. 2. Hattab FN, Qudeimat MA, al-Rimawi HS. Dental discoloration: An overview. J Esthet Dent 1999;11:291–310. 3. Joiner A. Tooth colour: A review of the literature. J Dent 2004;32:3–12. 4. Plotino G, Buono L, Grande NM, Pameijer CH, Somma F. Nonvital tooth bleaching: A review of the literature and clinical procedures. J Endod 2008;34:394–407. 5. Attin T, Paque F, Ajam F, Lennon AM. Review of the current status of tooth whitening with the walking bleach technique. Int Endod J 2003;36:313–329. 6. Macdonald-Jankowski D. Multiple idiopathic cervical root resorption most frequently seen in younger females. Evid Based Dent 2005;6:20. 7. Yu VS, Messer HH, Tan KB. Multiple idiopathic cervical resorption: Case report and discussion of management options. Int Endod J 2011;44:77–85. 8. Davis MC, Walton RE, Rivera EM. Sealer distribution in coronal dentin. J Endod 2002;28:464–466. 9. Watts A, Addy M. Tooth discoloration and staining: A review of the literature. Br Dent J 2001;190:309–316. 10. Rotstein I, Yiming L. Tooth discoloration and bleaching. In: Ingle JI, Bakland LK, Baumgartner JC. Ingle’s Endodontics, ed 6. Hamilton: BC Decker, 2008:1383–1399.

(9.1) CONSTANTIN VÂRLAN, BOGDAN DIMITRIU, IONUŢ BRÂNZAN (9.2) CAMELIA ALB, FLORIN ALB, IONUŢ BRÂNZAN (9.3/9.4) SMARANDA BUDURU, RAREŞ BUDURU

Chapter IX ESTHETIC RESTORATION OF ANTERIOR TEETH

9.1 DIRECT RESTORATIONS Direct adhesive techniques using materials based on composite resins are an excellent modality for the minimally invasive esthetic restoration of anterior teeth. They can be applied and finalized in a single chairside appointment, without the participation of the dental technician’s laboratory in most cases. Esthetic direct adhesive composite restorations allow the replacement of hard dental structures in the following cases: • Where they are irreversibly altered. • Where they have been lost, or show structural defects. • In disorders of carious etiology (simple caries lesions in vital teeth). • Non-carious etiology. • Wear lesions (such as attrition/abrasion/abfraction/erosion). • Traumatic lesions (in coronal location, without the irreversible involvement of the dental pulp). • Dystrophic enamel/dentin lesions.2,3,5,10 The treatment of tooth discoloration (related to its etiology) using direct laminate veneers represents a specific issue. Moreover, the reshaping of the coronal morphology (shape, size, 3D-positioning) of intact teeth, unaffected by the aforementioned lesions, can be achieved under correct functional conditions.6–8,10 9.1.1 Restorative materials The achievement of the expected esthetic results is undoubtedly related to the right choice and correct use of the restorative dental materials, according to the indications and techniques specific to each clinical situation. For that purpose, the value of such material is related1,4 to its physical and chemical properties, particularly its optical properties (multiple color shades, opacity/translucency, color stability); to its user-friendly handling; and to the final quality of the surface finishing and polishing. The technique must allow the acquisition of the shape and size, as well as the selection, establishment, and reproduction of the natural chromatic appearance of the restored tooth.2,3,5–10 This is why the currently used techniques are mainly based on various modalities of composite resins layering.5– 8,10 Enamel and dentin adhesive systems are components with a decisive role in the final result

of these restorations. Regarding the therapeutic approach of the substrate, their current development and variability offer high bonding forces, increased fracture and wear strength, and optimal marginal sealing, which will accord an increased longevity to the restorations.7,10 The first composite resins available for current use in practice were macrofill composite resins. They have a high degree of loading with irregularly shaped macroparticles, with a nonhomogeneous distribution and uneven sizes. Although they are mechanically strong, they have reduced esthetic qualities because of their optical properties and the surface texture obtained after finishing and polishing. For this reason they are not a convenient solution for this purpose.1,4,10 From an esthetic point of view, in order to reproduce the physical optical properties of enamel and the biological qualities of its surface, microfill composite resins are the highest performance composite materials that can be used for the direct restoration of anterior teeth. These materials contain a dense load of homogeneously distributed, uniform-sized spherical particles, which allow a long-duration polishing of the restored surface, together with a good wear resistance (particularly by abrasion/erosion) under normal functional conditions.1,4 Thus, such restorations do not support the formation of dental microbial plaque, and allow effective cleaning. Regarding their optical properties, microfill composite materials have reflection and refraction properties that are extremely similar to those of the dental enamel surface. This is why, after processing, finishing, and polishing, they reproduce this surface best in terms of smooth texture and lack of roughness, light reflection and refraction, color density, and translucency, conferring the natural vitality of the esthetic appearance, which can be observed immediately and in the short term, as well as maintained in the long term.6,8,10 The main problem related to the properties of microfill composite resins is the low resistance to fracture and high or excessive wear (particularly by attrition), which limits their use in locations where they are exposed to increased strain due to high occlusal forces.2,3,7,10 The first composite materials used to solve this problem (due to their good resistance to mechanical strain), and to replace microfill composite resins in the aforementioned situations, were microhybrid composite materials. Their physical properties include high resistance to compression and fracture, but their esthetic qualities do not equal those of micro- or nanofill composite materials. The mean size of small-size particles in microhybrid composite materials is 0.4 to 0.7 µm; large size particles reach 35 µm, conferring resistance and good handling properties to the material. However, they do not allow finishing and polishing of the surface in order to obtain a texture and a gloss similar to natural enamel, both immediately and in the

short term, and particularly in the long term.1,4,10 This is why the final esthetic appearance of microhybrid composite resin restorations, although clearly superior to that of restorations with conventional macrofill materials, cannot reach the level of micro- or nanofill composite resins. Due to their increased strength and opacity, these materials are extremely useful for stratified restorative techniques in anterior teeth, in order to reproduce the qualities of dentin (as a support for enamel) or, frequently, for masking darker or discolored areas.6,8,10 Nanofill composite resins (based on nanotechnology) are the most recently introduced materials used in daily practice for direct esthetic restorations. They are currently considered to be universal restoration materials for common situations – where esthetic requirements are not exceptional – while they can offer the following simultaneous advantages: • Very good handling properties. • Low polymerization shrinkage. • Fracture resistance. • Favorable optical properties with a color and a translucency close to that of natural teeth. • Good final polishing that results in a surface texture that reproduces the enamel. Apart from the above, they can also be used as a support for microfill composite resins, in which case the quality of translucency allows for the reproduction of the vital tooth appearance. However, compared to microfill composite resins, their final surface characteristics are not either quasi-identical or extremely similar to those of the dental enamel surface; nor do they perfectly mimic the natural vitality of the esthetic appearance.6,8,10 To summarize the adequate and appropriate selection of materials for direct esthetic restorations in anterior teeth: microhybrid composite resins are optimal to reproduce the properties of dentin (resistance, color, opacity), and to replace it. Nanofill composite resins (based on nanotechnology) and nanohybrid composite resins are the most frequently indicated as universal materials for most ordinary situations (with above-average esthetic requirements). Microfill composite resins can reproduce enamel characteristics (surface texture and gloss, translucency, light reflection and refraction) extremely well, and are therefore esthetically optimal for its replacement in restorations with exceptional requirements. These statements, supported by the theoretical and practical data presented by the current literature, lead to the conclusion that in most cases, the handling technique should be based on layering. This is due to the need to replace different hard dental structures and to reproduce the properties of each one in the best way possible to obtain optimal strength and esthetic appearance, as well as for

the longevity of the restorations.2,3,5–8,10 9.1.2 Auxiliary components: opacifiers and tints An extremely important aspect – unfortunately underestimated or even disregarded and thus insufficiently and sporadically applied in current practice – is the use of opacifiers and/or tints to improve the quality of the final esthetic result of direct composite restorations in anterior teeth.8,10 This is mainly due to incomplete and superficial information regarding the advantages that can be obtained from using them. Opacifiers are used to reduce the visibility of and mask discolored (most frequently, dark) areas inside the preparation, or to eliminate areas of unesthetic light refraction through the composite material. Really “invisible” restorations, which completely reproduce the “natural” appearance of the teeth, frequently require the adequate use of a kit of opacifiers with multiple color shades, compatible with the composite resin used.10 Tints are used to increase the incisal translucency or the cervical (gingival) basic shade and/or intensity (pigment load) of the initially selected color for the restoration material, according to needs. In order to make this effect possible, tints should be translucent (unlike opacifiers) to allow the refracted light to cross and “carry” the augmented color to the overlying composite material layer. Due to their increased translucency, microfill composites can offer this effect with maximum intensity, allowing the reproduction of the natural chromatic appearance of the restored tooth, starting with the inside. The possibility of improving the final result is another reason why this type of resin is indicated as a first option for direct restorations for the replacement of enamel in anterior teeth.10 Taking all of this into consideration, it appears that the most advantageous solution for direct esthetic restoration techniques in anterior teeth is the use of a complex set of components (each of which can be necessary at a certain step), where microhybrid, nanofill, nanohybrid, or microfill composites present different color shades in accordance with their different components and with the shade guide (color determination method) used; furthermore, for each shade there are various degrees of intensity (pigment “loading”),5,6,8,10 besides the opacifiers and the tints. Ideally, all these components (including the adhesive system used) should be perfectly compatible in terms of composition and structure, physical and chemical properties, technical

fabrication characteristics, and working modality (including optimal handling). 9.1.3 Clinical indications Direct esthetic restorations of anterior teeth using resin composite materials and adhesive techniques are currently widely used. Their current indications are extensive, ranging from ordinary (routine) restorations of caries lesions in class III, IV, and V cavities, to single or multiple (including complex, extensive) incisal/proximal/vestibular defects due to wear, trauma, or dystrophic lesions. A particular situation, with characteristic aspects, is the treatment of tooth discoloration (depending on etiology) using direct laminate veneers. Intact teeth, unaffected by the aforementioned lesions, can also be approached for coronal reshaping, in cases of diastema, microdontia, and atypical shapes, or for repositioning/realignment, as part of the complex reconstruction of the dental component of the dentolabial appearance (restoring/changing the smile design).5–10 In some of these cases, the indication of direct composite restoration can be discussed in relation to the degree of expertise, as well as the experience, of a particular practitioner, with a specific composite material and the working technique required for that material. However, apart from these situations (representing exceptions rather than the rule), the idea that these types of restorations should not be currently approached and performed because they are too difficult and do not have an adequate longevity is erroneous: if they are rigorously performed, and all clinical and technical indications are respected, direct esthetic restorations (including extensive, complex ones) with composite resins maintain their qualities and last for at least 8 to 10 years, while the number of reported and documented cases for which this period extends to 15 or even 20 years is constantly increasing.5–8,10 There are some opinions (coming from practitioners with vast experience) regarding these types of restorations that relate to the laborious and rigorous techniques and multiple procedures involved, some of which are delicate and require a fastidious approach. Furthermore, they require a significant extension of the time required for restoration and also increase the practitioner’s stress levels, as well as the risk of failure. These opinions cannot be considered relevant or decisive in light of the important advantages conferred by direct composite restorations in anterior teeth, which include the following:8,10 • As a rule, minimal preparations are required (some restorations can be performed, in certain situations, even without any preparation), which eliminates the additional (sometimes excessive) loss of intact hard dental substance and contributes to the patient’s comfort. They

minimize or even exclude the need for preparation under anesthesia. • Enamel and dentin adhesion (if correctly and efficiently performed) confers the retention of the restoration and the marginal integrity. It prevents microleakage and subsequent deterioration at this level. • Temporary restoration is no longer necessary. • The patient can benefit from the final esthetic result being obtained in a single appointment. • The dentist is in complete control of the final esthetic result and can continuously collaborate with the patient during the restoration. • Correction, reconditioning, or repair is much easier and faster to perform, with much better and more immediate results compared to other restoration modalities. For these reasons, due to current materials and techniques, these types of direct restorations can provide excellent chairside and single-appointment results that are highly esthetic, with a remarkable longevity. Furthermore, these types of restorations are examples of the application of minimally invasive principles in common practice.8,10 9.1.4 Specific aspects of dental preparations for direct composite resin restorations in anterior teeth The characteristics of dental preparation for these types of restorations in anterior teeth are determined by the performance of the adhesive bonding of the material to enamel and dentin. Clinically, this involves a number of aspects that correlate with the location and the surface area and depth of the defect that needs to be restored.6,8 Class III and IV preparations of small and medium size located only in the enamel require for the adhesive cavity (in addition to the concave regularization of the walls, after the removal of the irreversibly altered hard dental tissue) only a reduced circular marginal, beveled with a maximum 0.5 mm width. If the restoration of the incisal angle is involved, the shape, size, and modality of preparing the bevel should be correlated with the esthetic appearance and the extension of the restoration: extended preparations justify a bevel width of at least 1 mm. The surface of adhesion to the enamel should be larger, while the forces to which the restoration may be exposed will be higher.6 In order to mask the contour of the restoration on the buccal surface, the edges of the bevel will be slightly finished and polished, so as to be continuous, without clear delineation, with

the unprepared dental surface. At the initial preparation of a class III cavity, it is frequently possible to avoid the suppression of the buccal marginal crest and the involvement of the buccal surface in the restoration, which permits the achievement of a better esthetic result; in the case of an extended restoration, it will be difficult to avoid the implication of the buccal surface in the preparation. In this case, the most indicated solution is a fine circular bevel with a small flare.

Fig 9-1 Nonpenetrating fracture 21.

Fig 9-2 Preparation with a bevel and a retraction cord.

Fig 9-3 Silicone key.

Fig 9-4 Composite layering.

Fig 9-5 Final aspect – incisal view.

Fig 9-6 Final aspect – buccal view.

In class V buccal cavities, the bevel requires a reduced slope and less width, particularly in order to create a less visible progressive transition from the appearance of the restoration to that of the dental surface. In the case of lesions such as erosions/abrasions, preparation is often unnecessary, the finishing of the margins being sufficient (Figs 9-1 to 9-6).6,8 In principle, besides checking for the complete removal of the irreversibly altered hard dental tissue, any fragile or unsupported marginal enamel portion should be finally removed, because it will have an unfavorable effect on the adhesion at the enamel interface. On the other hand, the maintenance of these thin, irregular enamel margins will cause (after the placing of the composite resin) the so-called “prism effect,” due to light refraction through that enamel layer. The refracted light will create an obvious delineation between the restoration and the hard dental structure.6

Fig 9-7 Old discolored fillings 11, 12.

Fig 9-8 Placing of the rubber dam.

Fig 9-9 Cavity preparation.

Fig 9-10 Beveled preparation – palatal view.

Fig 9-11 Placing of celluloid matrix and wedge.

Fig 9-12 Removal of excess material with no. 15 blade.

Certain clinical situations allow the placing of composite resins for restoration without a preparation: most frequently, direct veneers or tooth reshaping (in cases of interdental spaces, or at the end of orthodontic treatments). Unlike indirect composite or ceramic laminate veneers, which require a well-defined thickness according to a preparation algorithm, there is no mandatory thickness for the material layer regarding the direct composite veneer technique without a preparation.6,8 A modified shape or discoloration may require coronal recontouring through selective buccal and incisal reduction, usually limited to the enamel layer (“enamel sculpting”).6 A special preparation form (“subs-tractive method”) consists of the selective reduction from the proximal area through interdental slicing. This is used, for example, for restoration cases presenting asymmetrically distributed interdental spaces, where it would be impossible to obtain equal widths in homologous teeth, or proportional widths in an anterior group of teeth, by using only the “additive method”.6

Fig 9-13 Finishing.

Fig 9-14 Final aspect after finishing and polishing.

Fig 9-15 Final aspect – palatal view.

Extended preparations are necessary for restorations that correct important position changes, dystrophic enamel lesions, or intense discoloration. The sequence of the preparation steps includes the initial stage of the main external contour, followed by the buccal surface; the

thickness of the material layer at this level may vary between 0.3 and 1 mm, depending on the desired correction regarding the position, shape, or color of the tooth.6,8 9.1.5 Composite layering – the multiple morphological layering technique The reproduction of the natural appearance of the color, translucency, and texture of the surface is determined by the propagation of light through the restoration (starting from the surface), through the composite mass applied over the residual enamel and dentin. In order to produce a natural three-dimensional effect, the composite mass should have optical properties identical or very similar to those of the enamel and dentin.2,3,6–8,10 However, it should be taken into consideration that microfill composite resins have a different light refraction index in comparison with natural prismatic enamel, and the placing of an “enamel composite” layer with the same thickness as that of natural enamel would result in a marked gray shade of the final restoration (Figs 9-7 to 9-15).6,8 This is why the artificial enamel layer should have approximately half the thickness of natural enamel, ie, about 0.5 mm. So, in contrast with the natural tooth, the multiple morphological layering of composite materials for the restoration of anterior teeth can be described as “dominated by dentin”, because the dentin mass core will have a greater volume than in the case of natural teeth.6,8 To achieve an optical appearance similar to that of the natural tooth, all restorations should present an “enamel composite” layer on their buccal, oral, or proximal surface. In order to avoid the undesired excessive marginal translucency effects (the so-called “halo effect”) in the areas of transition from the restoration limit to the natural enamel surface, the dentin composite layer with a basic (more opaque) shade must partially extend over the beveled enamel margin of the preparation. In that area, the enamel composite covering the dentin mass must be very thin.6 Usually, the working steps for this layering technique will be as follows:6

Fig 9-16 a Proximal cavity preparations in 11, 21, and 22.

Fig 9-16 b Final aspect of the restorations – buccal view.

Fig 9-16 c Final aspect – anterolateral view.

Fig 9-17 a Incisal fracture on 11.

Fig 9-17 b Final aspect.

Fig 9-18 a Old discolored fillings on 11.

Fig 9-18 b, c, d Restoration steps.

Fig 9-18 e Final aspect. (Images courtesy of Dr Stefan Arion.)

• Determination of the color (“chromatic map”) for the restoration of the tooth. • Construction of the dentin core (with several shades of dentin mass). • Use of opacifiers/tints (optional). • Selection of the basic shade for the enamel mass. • Specific “characterization” of the enamel layer (optional). 9.1.6 Matrices for the direct esthetic restoration of anterior teeth The current techniques for these restorations, depending on the clinical situation and the need to restore the of coronal contour and the interdental proximal contact area, can use several types of matrices:2,3,5–8,10 • Transparent matrix bands (with interdental wedges). • Prefabricated anatoform copings. • Silicone guides – by the impression of the oral surface. • Special matrices: cervical/proximal (individualized matrices). A special mention should be made of the increasing frequency of the recommendation and use of proximal matrices “open” towards the vestibular and oral surfaces, which allow a much more convenient access for layering and modeling.6–8 For the majority of authors who recommend and use direct composite restorations, in addition to using matrices (considered to be mandatory in proximal restorations), the use of freehand sculpting of coronal morphology is essential. This is because it allows for creativity and adds to the quality of the final result (Figs 9-16a to 9-18e).6–8,10

REFERENCES 1. Powers JM, Sakaguchi RL. Craig’s Restorative Dental Materials, ed 12. St Louis: Mosby Elsevier, 2006:189– 212. 2. Hilton TJ, Ferracane JL, Broome JC. Summit’s Fundamentals of Operative Dentistry. A Contemporary Approach, ed 4. Chicago: Quintessence, 2013. 3. Heymann HO, Swift Jr EJ, Ritter VA. Sturdevant’s Art and Science of Operative Dentistry, ed 6. St Louis: Mosby Elsevier, 2013. 4. O’Brien WJ. Dental Materials and their Selection, ed 4. Chicago: Quintessence, 2008. 5. Brenna F, Breschi L, Cavalli G, et al. Restorative Dentistry: Treatment Procedures and Future Prospects. St Louis: Elsevier Mosby, 2009. 6. Hugo B. Esthetics with Resin Composite. Basics and Techniques. Chicago: Quintessence, 2009. 7. Mangani F, Putignano A, Cerutti A. Guidelines for Adhesive Dentistry. The Key to Success. Chicago: Quintessence, 2009. 8. Terry DA, Leinfelder KF, Geller W. Aesthetic and Restorative Dentistry: Material Selection and Technique. Stillwater: Everest Publishing Media, 2011. 9. Ricketts D, Bartlett D. Advanced Operative Dentistry: A Practical Approach. London: Churchill Livingstone, 2011. 10. Freedman G. Contemporary Esthetic Dentistry. St Louis: Elsevier Mosby, 2012.

9.2 PORCELAIN LAMINATE VENEERS 9.2.1 Motivation Porcelain laminate veneers (PLVs) are currently the treatment most in demand in esthetic dentistry: patients request them daily; dentists recommend them whenever possible, depending on the particular clinical case; and, for dental technicians who fabricate them, they represent the highest technical expertise of their laboratories. This is a highly elective dental treatment, so everybody involved in it – patient, dentist, dental technician – is very motivated to achieve a beautiful smile that is as close as possible to perfection. In the 21st century, beauty and physical attractiveness are considered to be directly correlated with social, professional, or personal success. Social and psychological studies have unequivocally shown that people perceived as beautiful by their peers earn higher salaries, are more easily employed, receive more favorable decisions in court, and have a better chance at finding a life partner than ordinary-looking people. The face is the most important aspect of the entire physical appearance, and with the smile at its center, it is easy to understand why it induces a reaction from those who perceive it. Porcelain laminate veneers have become so popular because they meet several important requirements: • Biological: they are very conservative with the dental tissues and, in most cases, do not require subgingival preparations. • Functional: even though PLVs are extremely thin and breakable, due to the low flexural strength of the ceramic, the tooth-veneer complex is extremely resistant over time. • Esthetic: they reproduce the natural teeth almost perfectly, due to the optical properties of sintered ceramic. • Reliability: PLVs provide very stable results over time, without chromatic changes;1 • Economic: the most frequently used veneers (feldspathic and pressed veneers) do not require expensive investments in the laboratory or the dental office, so theoretically they can be made by any dentist and any ceramist who has the knowledge and can master the procedures. Veneers started their journey in 1928, with the first acrylic resin veneers made by Charles Pincus for Hollywood actors, who only wore them for several hours while shooting a movie.

Then Pincus started to apply porcelain veneers onto teeth without special preparation. This was followed by today’s modern concept of veneers. The use of veneers would not have been possible without the discovery of adhesion through the acid etching technique introduced for the first time by Buonocore in 1955, as well as the etching treatment of the porcelain surface discovered by Rochette in 1973. PLVs were introduced by Horn in 19832 under the name of porcelain labial veneers, and were developed by authors such as Ronald Goldstein, Pascal Magne, Urs Belser, Galip Gürel, Eduard McLaren, Michel Magne, David Garber, and Horn, who have done extensive work and research in this field, and published many books and articles. A review by Della Bona of over 400 articles published between 1993 and 2008 on the longevity of ceramic veneers concludes that their success rate is over 90% in all single-tooth restorations in the anterior area, regardless of the ceramic system used.3–5 Many studies were carried out on certain types of ceramics: Fradeani, in his study on 83 Empresspressed veneers, reported a 6-year success rate of 98.8%,6,7 while other studies have reported a 12-year success rate of 91%.8,9 9.2.2 Clinical indications for PLVs When introduced in the 1980s, PLVs had very few clinical indications because of the poor physical properties of the ceramic masses. Today, the indications for PLVs have been considerably extended and they are successfully used in many clinical situations: • Minor malpositions (rotations, lingual tilting). • Shape and size abnormalities (undersized or conical teeth), enamel dysplasia or dystrophia. • Mild or moderate changes in the shape of dental arches. • Closure of interdental spaces, physiological or pathological abrasion. • Fractures of anterior teeth in the incisal and middle thirds. • Single-tooth discoloration (non-vital teeth) or generalized discoloration, most frequently found in relation to antibiotic treatment, that is resistant to oxidative whitening procedures or have relapsed after such treatments (Figs 9-19a and 9-19b).10 Absolute contraindications include: • Non-vital teeth with extended class III or class V composite restorations. • Teeth with severe position changes (severe rotation, inclination, translation) that cannot be

corrected through preparation and veneers but only with orthodontic treatment. • Occlusal disorders that cannot be corrected by prosthetic rehabilitation. The following can be considered as relative contraindications: • Severe discoloration that cannot be masked by veneers. • Bruxism (in certain cases). • Teeth with old composite restorations on more than two dental surfaces. • Teeth with advanced enamel abrasion, particularly on the buccal surface.11,12

Fig 9-19 a,b. Single-tooth discoloration of endogenous cause – clinical case before and after internal bleaching with Opalescence Endo (Ultradent). Although immediate results are good, internal discoloration will relapse within 2 to 4 years.

9.2.3 Case selection and treatment planning Restoration of teeth using ceramic veneers is a reliable and long-lasting treatment option when applied correctly for the right indication, with a good treatment plan, if all the details and techniques are strictly followed in the office and in the dental laboratory.13 Even the most

experienced cosmetic dentist will not always obtain a 100% success rate. Most frequently, failures occur because of inadequate clinical indication, insufficient case analysis, or lack of communication between dentist, patient, and ceramist, which results in the general dissatisfaction of all parties concerned. This is why the authors strongly recommend that any esthetic case should start with several preliminary sessions involving the documentation of the case, initial discussions with the patient in order to understand his/her expectations, an esthetic analysis with the team of specialists, and, finally, the detailed presentation of the treatment plan to the patient. Esthetic case documentation The documentation of esthetic cases includes: • Complete medical records. • An esthetic questionnaire for self-evaluation. • A complete set of intraoral and facial photos. • Study or diagnostic casts. • The record of the occlusal relations using high-performance methods. • The use of the facebow to mount the study cast in the articulator. • Full-mouth radiograph. • Lateral cephalometric and/or CT scans (in more complex cases). Esthetic analysis of the clinical case The esthetic analysis of the clinical case should be done before offering any treatment plan to the patient. For complex cases, we should involve a team of specialists: an orthodontist, a periodontologist, an oral surgeon, and, of course, one or more highly trained dental ceramists. The esthetic analysis will include: examination of the dental proportions; the dental arches; the gingival esthetic criteria; the dentofacial aspect; the facial esthetics; and analysis of the occlusion. These aspects are detailed in Chapter II.1,10 After this analysis, a complex and well-documented esthetic treatment plan can be presented to the patient in a second appointment. As Dr Elliot Mechanic pointed out, “our patients did not go to dental school”, so it is generally difficult to explain to patients the proposed treatment plan and esthetic procedures using only words. In most cases, dentists need to add other modern means of communication to correctly convey the message to patients, and also to increase treatment acceptance. Generally, when we restore a patient’s smile with porcelain veneers, we perform a

treatment of choice. Precisely because of this, it is absolutely necessary to establish a perfect communication with the patient (described in detail in Chapter IV) before starting any irreversible procedure, such as the preparation on those teeth that the patient wishes to change. We strongly advise against dentists starting from the first appointment directly with the preparation, impression, cast and fabrication of ceramic veneers in the laboratory simply because the patient is eager to change his/her appearance. By so doing, we can end up in the unpleasant situation of being at the final stages of try-in or cementation, with the dentist not having completely understood the patient’s expectations, or the patient not having been able to see what could have been achieved at the end of the prosthetic treatment.

Fig 9-20 a. Clinical case analyzed by Digital Smile Design: analysis of dental arches in buccal view, with the outline of the contour of maxillary anterior teeth. b. Contours and initial analysis, on which the possible changes proposed by the dentist are based, and then discussed with the patient. c. Measurements of the changes proposed for the dental technician. d. Provisional work according to the mock-up. e. Checking the temporary restorations in the patient’s mouth for the validation of the DSD project. f. Final esthetic solution using e.max Press crowns on the four maxillary incisors and e. max Press veneers on the canines. (Images courtesy of Dr Dan Lazăr.)

This is why the authors recommend that any change in the esthetic area – particularly through irreversible prosthetic restorations – should be preceded by the use of the most modern dentist–patient–ceramist communication methods, in order to ensure that the patient has understood the initial clinical situation, the limitations of the case, the chosen materials, as well as the final result proposed by various computer software or model simulation methods, or direct and indirect mock-up in the mouth. 9.2.4 Simulation of the final esthetic result The easiest and most accessible method in terms of time and cost for any dental office is visual communication using computer imaging that utilizes either image-editing software (such as Photoshop) or specialized software (such as Digital Smile Design [DSD]) (Figs 9-20a to 920f). DSD, patented by Dr Christian Coachman, is a very modern and interesting concept of digital image analysis in dentistry that has been used over the past few years. Starting from initial digital photos and/or video records of the patient, DSD digitally manipulates the image to simulate the final appearance of the patient’s teeth and smile. Another technique used to simulate the final result is the direct mock-up. This is done by the dentist directly on the tooth in the patient’s mouth, using direct light-curing composite resins, in

an attempt to show the patient certain changes. The technique is time-consuming and is rarely used today; when it is used, it is only done on one or two anterior maxillary teeth, never in the case of complex, full-mouth rehabilitations. The direct mock-up serves us well when restoring a tooth fracture, simulating crown lengthening in cases with abrasive wear, and for masking discoloration, but it cannot be used in cases with labial protrusion, or in esthetic treatment plans that require tooth reduction. The diagnostic wax-up is another frequently used technique performed by the dental technician in the laboratory on the initial cast. A special type of wax is used – ivory wax – which mimics the appearance of natural teeth (eg, Creation Set, Kohler). There are many advantages to this method: • The functional individualization according to the occlusal parameters registered on the patient and transferred to the articulator. • The possibility of creating beautiful tooth shapes in cases that require tooth structure reduction or gingival remodeling surgery, which cannot be achieved by direct mock-up. • Saves time for the dentist, who only needs a good-quality impression and a set of initial photos (described in detail in Chapter III), the majority of the changes being performed on the models in the laboratory. Starting with the initial cast of the patient, the dental technician proposes shapes and position changes, which can then be transferred to the final veneers. However, it is difficult for a patient to imagine how a perfect wax-up on a gypsum cast will look in his/her mouth – how it will integrate with his/her smile and facial features. The most frequently used technique nowadays is the indirect mock-up, performed by the dentist in the dental office by transferring the wax-up to the patient’s mouth. The cast with the wax-up is duplicated in the dental laboratory, and a vacuum-formed tray and/or transparent silicone impression is made on the new plaster model to obtain the negative of the esthetic wax-up. This is then transferred into the patient’s mouth using dual-curing composite resin. These templates of the final result made in composite in the patient’s mouth based on the wax-up in the laboratory have been named “aesthetic pre-evaluative temporaries” (APTs) by Gürel in his book The Art and Science of Porcelain Laminate Veneers, or bonded mock-up by McLaren, or simply, indirect mock-up.11,14,15 It is an inexpensive method, accessible to any dental office and laboratory. Although it is time-consuming, it allows the patient to see directly the final esthetic result proposed by the

dental and technician team. These APTs allow patients to try out the proposed changes in their own mouths, with their own particular dental and facial esthetic appearance when smiling, speaking, or laughing. Another important advantage of this method is that patients can ask for a second opinion from the people who are close to them and whom they trust. A major feature of APTs is that, although dentists are able to perform a number of length or shape changes as requested by patients, they are not able to do so directly on the mock-up, which is not adhesively bonded to the teeth. Patients can wear the mock-up for several hours to test the length of the incisal margin, or the shape and position of the anterior teeth. However, it is easily removed – and indeed must be – for the mastication function. However, this cannot be achieved in all cases without reshaping the teeth – the most typical problems are teeth in protrusion, rotated in the labial direction and in the lateral area, and extruded teeth, with changes in the occlusal plane. In these cases, after the placing of the vacuum-formed tray on the non-prepared dental arch, there will be teeth that touch or even distort this guide, where, consequently, there will be no covering of composite material. The reshaping of the enamel of those areas is required in order to make the mock-up – a clinical step termed “aesthetic pre-recontouring” (APR) by Gürel.11 Another long-term mock-up solution is the bonded functional esthetic prototype (BFEP) described by McLaren, in which, using the thermoformed tray or the silicone guide, a microfilled composite resin with improved mechanical properties is applied to the teeth that have been treated with acid and bonding agent. The result is a mock-up, which is adhesively bonded to the entire dental arch and can be worn by the patient for esthetic and functional testing over a period of up to 4 or 5 years.16

Fig 9-21 a-e Guided preparation for veneers through the mock-up, starting from the final shape of the teeth.

9.2.5 The guided preparation of teeth for veneers In esthetic dentistry today, preparation which involves the removal of the same amount of tissue all around the teeth (according to conventional principles) is no longer accepted. The modern approach starts exactly in the opposite direction, from the end result that is desired. The amount of tissue that is removed from each tooth is dictated by the final shape and position of the teeth with the bonded veneers in place, established in agreement with the patient by means of the esthetic project, and reproduced by the mock-up. Given that in APTs the teeth are correctly aligned and recontoured, the preparation is almost completely achieved through this mock-up, and will be the same as for an absolutely ideal case (Figs 9-21a to 9-21e).

Fig 9-22 a-d Various preparation designs for veneers.

In the majority of cases, a wax-up is made in the laboratory. Using this as the basis, a duplicate model and a thermoformed tray are created. An indirect mock-up is obtained in the patient’s mouth using the thermoformed tray, by the injection of a dual-curing composite resin. Teeth preparation is done through this composite mock-up, with depth orientation grooves and special design burs.

From the final mock-up, a uniform thickness of 0.5 to 0.7 mm on all teeth needs to be reduced. Many authors recommend a diamond-guide bur that creates three grooves of equal depth in the three thirds of the buccal surface. As the easiest depth-guiding method, a spherical diamond bur 1.4 mm in diameter is recommended, which creates a 0.6 mm space. First, the labial surface is prepared with a cylindrical round-head bur, which is maintained angulated in the three planes in order to respect the convex morphology of the buccal surface. At the cervical margin, the preparation ends with a rounded shoulder, placed in the majority of cases above the gingival margin.11,17 It is advised that a wider shoulder be used, placed slightly below the gingival margin but only on the buccal surface in the case of severely discolored teeth, in order to mask the limit between the brighter surface of the ceramic and the darker surface of the unprepared tooth. Also, the preparation should be extended deeper on the proximal surfaces, below the contact point, with the bur maintained at a 60-degree angle. Otherwise, a dark line that limits the veneer and the tooth at the level of the proximal side will be visible.11 Once the buccal surface has been prepared, the proximal surfaces are next. This is required especially in the case of old class III composite restorations that need to be restored and included in the preparation. The incisal convergence of the surfaces should also be respected. The contact points will be maintained or suppressed, depending on the extension of class III restorations and on the degree of convergence of proximal surfaces.16 Following that, the lingual surface is prepared, which may or may not be included in the veneer. Once the preparations are complete, the residual mock-up is removed from the teeth with a Gracey curette. There are three types of classical veneers, according to the extent of the preparation (Figs 922a to 9-22d): • Window veneers – limited to the buccal surface, not including the incisal margin and without the removal of contact points. • Veneers covering the incisal edge – prepared at a 60-degree angle, ending with a rounded shoulder on the oral surface. Very importantly, the porcelain-tooth junction should never be placed at the level of occlusal contact points with opposing teeth. • Extended veneers – include the buccal surface, oral surface, and incisal edge, and the suppression of one or both contact points.12 Due to the evolution of the adhesive technique, there are currently unlimited possibilities for

porcelain restorations of different shapes, in various clinical indications. These no longer need to respect the rigor of a classical preparation. The different veneer types therefore vary considerably: • No-prep veneers for undersized dysmorphic teeth, enamel delaminations, an anterior group in mild retrusion, and cases of abrasion of the buccal enamel. • Microveneers that restore a fractured incisal margin, an incisal angle, or an occlusal cusp, from 0.5 to 2 mm. • Proximal microveneers applied for the closure of interdental space. • Buccal veneers (in accordance with the classical meaning of the term) or lingual veneers, for the restoration of canine guidance in patients with palatal abrasion or gastroesophageal reflux. • Extended veneers or three-quarter veneers, which include the entire buccal surface and the proximal and oral surfaces, leaving the cingulum area unprepared. Magne showed that it is useless to try to classify porcelain veneers because of the complex forms they have taken nowadays. He proposed a new term – bonded porcelain restorations (BPRs), which includes all adhesively bonded porcelain restorations, regardless of the group of teeth, the tooth surface on which they are applied, or the extension of the preparation.1 Choosing the veneer type The choice of the type of veneer depends on several factors,22–24 the main one being the available space that can be estimated during the 3D simulation phase of the final position of the restored teeth – recommended by Gürel, McLaren, and other authors since 2003. They have demonstrated that dentists should not remove a uniform layer of tooth structure on all prepared surfaces during the preparation for veneers. On the contrary, the approach should be from the opposite direction; from the final esthetic result.11,18 The second factor is the dental substrate: if the dentist starts from a vital tooth, the preparation should be limited to the enamel, to tenths of a mm (0.2 to 0.7 mm). However, for a non-vital tooth, a ceramic system should be chosen, one that has various degrees of opacity to be able to mask the discoloration. An example is the e.max Press system from Ivoclar Vivadent, which has various degrees of translucency and opacity, from low translucency (LT) to maximum, high-opacity (HO) pressed porcelain. In cases of the combination of vital and non-vital teeth in the anterior maxillary area, the preparation needs to be changed. The calculation formula introduced by Gürel is generally accepted today: for a color change of one shade from A2 to A1, or from 2M1 to 1M1, the

dental technician will need 0.2 to 0.3 mm more space in the case of feldspathic porcelain. This thickness differs depending on the ceramic material, feldspathic porcelain having an increased translucency (leucite glass ceramic has comparable properties). However, the majority of experienced ceramists and dentists recommend a space of more than 0.8 mm, up to 1 mm, in discolored teeth.11 Patient-dependent factors The crucial element for a successful veneer restoration is perhaps the control of excessive parafunctional occlusal forces that should be considered at the start of the design of the treatment plan. As a general principle, there is an indirect correlation between porcelain fracture resistance and optical properties, so that feldspathic porcelain with the highest translucency has the lowest flexural strength (60 to 80 MPa), while, at the opposite end of the scale, zirconia ceramic has the highest strength (900 MPa), but the lowest light transmission.18–20 9.2.6 Current technologies for the fabrication of veneers in the dental laboratory There are currently three main techniques for the manufacturing of porcelain veneers in the laboratory: • Firing layers of feldspathic porcelain powder on a refractory die or a platinum foil – feldspathic veneers. • The press technique, or pressed veneers (the prototype is the e.max Press, IvoclarVivadent). • The CAD/CAM milling technique, performed either in the dental office (with an in-office CAD/CAM system, eg, CEREC, Sirona or E4D, D4D Technologies) or in the dental laboratory, using the in-lab systems. (The last technique is detailed in Chapter V, so here we will only discuss some specifics related to veneers [Figs 9-23a and 9-23b]). The technique of feldspathic veneers is the oldest, and the most expensive, of the three types of veneers in Western Europe and the USA. It is a sophisticated and very laborious method, but offers perfect esthetic results, allowing for the amazing reconstruction of apparently impossible cases. The technique is more demanding because it requires the fabrication of three different gypsum models, including a special one, with removable dies made from refractory material – also known as the Willi Geller model – which reproduces the soft tissues around the

dies. The procedure also requires an experienced dental ceramist, because no subsequent corrections are possible with this technique after the try-in phase in the dental office.21,22 The first layer includes transparent ceramic powders at the margins of the preparation that allow optical mimicry to work in this area. In some cases, where teeth are severely discolored, an opaque ceramic powder is used. The purpose of the second layer is to render the final shape and functional integration; this step will be performed in the articulator. The third layer is aimed at providing texture details and minor shape changes or corrections. It is performed with translucent or heavily modified chromatic ceramic powders, if stains are required in some artistic veneers. Pressed veneers are the most popular veneers among dental ceramists worldwide because they are extremely easy to fabricate using the lost wax technique. Also, they are not very timeconsuming and are made from a stronger ceramic. In contrast, this technique is less flexible in cases where a deep chromatic characterization and individualization is needed, when compared to feldspathic veneers, which is why they are mainly recommended for symmetrical restorations. They can be pressed as thin as 0.3 mm, which allows them to be used for prepless veneers, or as thick as 3.5 mm, the case of table-top restorations, due to their increased strength.23,24

Fig 9-23 a, b Different bonded porcelain restorations (after Pascal Magne) a. IPS e.max Press veneers (Ivoclar) with various extensions on the anterior teeth. b. Feldspathic porcelain veneers (Vita VM 7, Vita) – the most esthetic – with a thickness of 0.4 mm on the buccal surface, and 1.5 mm on the incisal margins.

Fig 9-23 c, d Clinical results before and after the adhesive cementation of three feldspathic microveneers (12, 11, 21).

The increased scanning accuracy, the increasingly faster intraoral scanners, the user-friendly software, the same-day luting (so no need for an extra appointment), and the option of milling

porcelain veneers, inlays, and onlays in one hour in the dental office, have led to the increasing popularity of CAD/CAM systems. However, it is extremely hard to meet the highest esthetic demands without a final glazing and staining in a ceramic furnace.21 Until recently, only sintered ceramic blocks were milled; nowadays, pre-sintered ceramic blocks have also appeared on the market, such as those made by Ivoclar Vivadent.23,25 9.2.7 The adhesive bonding of veneers The most accurately fabricated veneer, the most talented ceramist, and the most advanced technology will not be able to ensure durability and an exceptional final result in the absence of particular attention paid to the last clinical stage, adhesive bonding, which is detailed in Chapter XI. An issue still being researched is to what extent zirconia veneers can be conditioned, as they do not have a glass content, and consequently the question of what adhesion is obtained with the so-called “zeneers” is under investigation. These veneers made from zirconia require special surface treatment. The rest of the ceramics, feldspathic and glassbased, have a sufficient glass-ceramic content, so hydroflouric acid treatment and subsequent silanization represent a very good method for increasing adhesion by up to ten times.18 Both surfaces – the prepared dental surface and the internal surface of the veneer – require specific treatment before the placing of adhesive cement. This treatment dramatically increases the quality and reliability of adhesion.26 The internal surface of the veneer is prepared first, only after it has been tried in the oral cavity. The majority of authors recommend: 4% hydrofluoric acid etching for 90 seconds; washing with hot water; neutralization with sodium bicarbonate in aqueous solution; cleaning in an ultrasound bath; drying and heating; placing of a two-component silane; and covering with a glass lens to prevent the contamination of the treated surface.11,18 For the treatment of the dental surface, three-stage adhesive systems are preferred: acid–primer–bonding (A-P-B). This is because some self-etching adhesive systems are not compatible with dual-resin composites. Some studies have shown that adhesive systems comprising three-stage etching and washing produce longer-lasting composite-dentin bonds than single-stage or two-stage adhesives.26 The simultaneous acid treatment of dentin and enamel is to be avoided, because unprepared enamel takes 80 seconds to correctly demineralize, while dentin only takes 15 seconds. In prepless veneers, the enamel surface is activated with an extra-fine bur or abrasive discs, and where there are old composite restorations that have not been replaced, a composite primer layer is applied, which reactivates the composite surface for an ideal adhesion. The primer and bonding are applied

on the prepared tooth surface according to the manufacturer’s instructions, with extra care being taken because too thick a layer of bonding in veneers can prevent the seating of the veneer in the final position. This is why the bonding is generally light-cured, together with the luting cement, only after the veneer is fixed in the final position. Attention should be paid to veneers for which accurate positioning is not possible, such as prepless veneers or additional microveneers, where incorrect positioning is difficult/impossible to correct. A minimal amount of adhesive cement is applied on both surfaces with a brush, making sure that both surfaces are perfectly wetted with it. Depending on the insertion axis and the number of veneers, the procedure starts from the midline towards distal, preferably with the simultaneous cementation of the two central incisors. Partial polymerization for 1 to 2 seconds, until the luting composite becomes gel-like, considerably facilitates the removal of excess and subsequent finishing. At this stage, the presence of air inclusions can also be verified without remaking the veneer, which can be easily removed, cleaned, and recemented. Finally, at the transition zone between the veneer and the tooth, the final setting of the resin should be done with a glycerin gel, which prevents the formation of an oxygen-inhibited layer at the surface of the resin.

9.2.8 Clinical cases Case 1: Veneers on teeth 12 and 22

Fig 9-24 a Initial clinical situation.

Fig 9-24 b Control model.

Fig 9-24 c Veneers on the control model.

Fig 9-24 d Cemented veneers: frontal view.

Fig 9-24 e Cemented veneers: palatal view.

Fig 9-24 f Esthetic appearance during smiling.

Case 2: Veneers on teeth 11 and 21

Fig 9-25 a Initial clinical situation.

Fig 9-25 b View of minimally invasive preparations, limited to the enamel thickness.

Fig 9-25 c Veneers on the control model.

Fig 9-25 d Veneers made using the refractory die.

Fig 9-25 e, f Clinical views of veneers one week post-cementation.

Fig 9-25 g Cemented veneers: palatal view.

Fig 9-25 h Esthetic appearance during smiling.

Case 3: Veneers on teeth 11, 13, 21, and 23

Fig 9-26 a Initial clinical situation.

Fig 9-26 b Occlusal view.

Fig 9-26 c Tooth preparations for veneers and crowns.

Fig 9-26 d Single-stage impression (Impregum, 3M ESPE).

Fig 9-26 e–g Clinical views 2 years after cementation.

Fig 9-26 h Esthetic integration of porcelain restorations.

Case 4: Veneer on tooth 22

Fig 9-27 a Initial clinical situation – the patient was dissatisfied with the tooth shape and size.

Fig 9-27 b View of the minimally invasive preparation limited to the enamel thickness.

Fig 9-27 c Cemented temporary veneer.

Fig 9-27 d Porcelain veneer after rehydration.

9.2.9 Conclusions Although porcelain veneers had many limitations initially, in recent years their use has become increasingly widespread due to the standardization of in-office and in-lab techniques. This has happened on account of the development of dental ceramics, with significantly improved mechanical and optical properties, which has permitted dentists to esthetically restore damaged teeth with minimal-thickness ceramic layers, and obtain a 10-year success rate higher than 90%.11 There are currently several options for the production of porcelain veneers. Some are more laborious and require considerable workmanship from the technician and an increased length of time, such as feldspathic veneers on a refractory die. These also yield the best esthetic results and give absolute freedom to the dental ceramist. Other techniques, such as the pressed veneers, are easier and more accessible. They are cheaper, faster, and very easy to handle, with good reproducibility, and are accessible to any dental laboratory and ceramist. The third option is the CAD/CAM systems, in which the computer performs most of the optical scanning, the virtual model, the design, and the milling procedures, thus eliminating almost completely the human-error factor. The reduced cost, the standardization of veneer fabrication in the office or dental laboratory, and the ability to produce as many as 500 milled porcelain restorations per week, will certainly lead to an increased use of these machine-made systems, compared to the use of hand-made veneers skillfully fabricated by the dental technician. Professor Edward McLaren demonstrated this in his course, suggestively entitled Ceramic Artistry – Man versus Machine: A Ceramic War.19 Yet despite the progress made by computerized milling systems, in difficult cases, such as the esthetic restoration of a maxillary

central incisor in an intact dental arch, CAD/CAM-milled porcelain cannot yet perfectly mimic all the details that give life to the natural structure of human teeth. In these cases, a final optimization performed by a ceramic technician is absolutely necessary.

REFERENCES 1. Magne P, Belser U. Bonded Porcelain Restorations in the Anterior Dentition: A Biomimetic Approach. Chicago: Quintessence, 2002. 2. Horn HR. Porcelain laminate veneers bonded to etched enamel. Dent Clin North Am 1983;27:671–684. 3. Della Bona A, Kelly JR. The clinical success of all-ceramic restorations. J Am Dent Assoc 2008;139(suppl 4):8S–13S. 4. Freidman MJ. A 15-year review of porcelain veneer failure: A clinician’s observations. Compend Contin Educ Dent 1998;19:625–630. 5. Peumans M, Van Meerbeek B, Lambrechts P, Vanherle G. Porcelain veneers: A review of the literature. J Dent 2000;28:163–177. 6. Fradeani M. Six-year follow-up with Empress veneers. Int J Periodontics Restorative Dent 1998;18:216–225. 7. Wiedhahn K. CEREC veneers: Esthetics and longevity. In: Mörmann WH (ed). State of the Art of CAD/CAM Restorations. 20 Years of CEREC. Berlin: Quintessence, 2006:101–112. 8. Layton D, Walton T. An up to 16-year prospective study of 304 porcelain veneers. Int J Prosthodont 2007;20:389–396. 9. Fradeani M, Redemagni M, Corrado M. Porcelain laminate veneers: 6- to 12-year clinical evaluation – a retrospective study. Int J Periodontics Restorative Dent 2005;25:9–17. 10. Goldstein RE. Esthetics in Dentistry, vol I, ed 2. Hamilton: BC Decker, 1998. 11. Gürel G. The Art and Science of Porcelain Laminate Veneers. Chicago: Quintessence, 2003. 12. Touati B, Nathanson D, Miara P. Esthetic Dentistry and Ceramic Restorations. London: Martin Dunitz, 1998. 13. Gürel G. Predictable and precise tooth preparation techniques for porcelain laminate veneers in complex cases. Int Dent SA 2007;9:32–40. 14. McLaren EA, Bazos M. Controlling tooth reduction and the bonded mock-up: Part 1. Inside Dentistry 2007;3:96–100. 15. McLaren EA, Vigoren G. Preparations and controlling tooth reduction. Part 2: Crowns and fixed partial dentures. Inside Dentistry 2007;3:86–90. 16. McLaren EA, Schoenbaum TR. The bonded functional esthetic prototype: Part 1. Inside Dentistry 2013;9(1):58–59. 17. McLaren EA. Porcelain veneer preparations: To prep or not to prep. Inside Dentistry 2006;2:76–79. 18. Lasserre JF, Laborde G, Koubi SA, et al. Restaurations céramiques antérieures (2): Préparations partielles et adhésion. Réal Clin 2010;21:183–195. 19. McLaren EA, Whiteman YY. Ceramics: Rationale for material selection. Inside Dentistry 2012;2:38–52. 20. Belser UC, Magne P, Magne M. Ceramic laminate veneers: Continuous evolution of indications. J Esthet Dent 1997;9:197–207. 21. Sailer I, Feher A, Filser F, Gauckler LJ, Luthy H, Hammerle CH. Five-year clinical results of zirconia frameworks for posterior fixed partial dentures. Int J Prosthodont 2007;20:383–388. 22. McLaren EA, Chang YY. Creating physiologic contours using a modified Geller cast technique. Inside Dentistry 2007;3:88–91. 23. Ivoclar Vivadent. IPS e.max Lithium Disilicate: The Future of All-Ceramic Dentistry. Amherst: Ivoclar-Vivadent,

2009:1–15. 24. Koubi SA, Margossian P, Weisrok G, Lasserre JF, et al. Restaurations adhésives en céramique: Une nouvelle référence dans la réhabilitation du sourire. Info Dentaire 2009;91:363–367. 25. Magne P, Stanley K, Schlichting LH. Modeling of ultrathin occlusal veneers. Dent Mater 2012;28:777–782. 26. Pashley DH, Tay FR, Breschi L, Tjäderhane L, Carvalho RM. State of the art etch-and-rinse adhesives. J Dent Mater 2011;27:1–16.

9.3 ALL-CERAMIC CROWNS The high esthetic requirements relating to the anterior area can be associated with the current tendency towards minimally invasive dentistry. This is aimed at performing esthetic and functional changes with only minimal involvement of the dental structures. Unfortunately, there are cases in which minimally invasive dentistry is impossible due to the clinical situation: teeth with massive structure loss, non-vital teeth with a minimal amount of residual enamel, or teeth that have already been prepared for anterior crowns. Where an all-ceramic crown is required, it would be appropriate to answer several questions in order to make the correct decision: • What ceramic system should be used? • What type of preparation is indicated? • What type of cementation is adequate? • What is the long-term durability? Classification of all-ceramic systems The multitude of all-ceramic systems available on the market, and the great number of existing producers, each with their own brands, may cause confusion among clinicians. This confusion can result in, for example, a reluctance to use one system, or the erroneous use of another. We consider it useful to include a brief review of these ceramic systems. One possible classification is according to ceramic microstructure (less accepted by clinicians); another more simple one is according to technological processing.1 This is a classification according to ceramic microstructure: • Glass systems (mainly silicates): feldspathic porcelain. • Glass systems (mainly silicates) with different fillings (leucite, lithium disilicate): pressed ceramics. • Crystalline systems with glass filling (particularly alumina): In-Ceram (spinell, alumina, zirconia). • Polycrystalline solid systems (alumina and zirconia). A simpler and friendlier classification refers to the processing modality: • Conventional liquid/powder mixture.

• Pressing. • CAD/CAM processing (subtractive, by milling; or additive, by electrodeposition). A third, less-scientific classification of clinical interest would be (only for the anterior area): • All-ceramic crowns without an internal substructure: feldspathic porcelain fired on a refractory die or on a platinum foil. • All-ceramic crowns with internal substructure and layering. Internal copings can be made from pressed ceramics, zirconia, and In-Ceram. 9.3.1 All-ceramic crowns without an internal substructure This type of crown is made of feldspathic porcelain fired on a refractory die or a platinum foil. This porcelain is currently used for layering over a substructure (metal or ceramic), or for the fabrication of veneers. Porcelain has an extraordinary translucency, which makes the restoration seem particularly natural. Unfortunately, the in vitro flexural strength is low (up to 100 MPa).

Fig 9-28 a Initial situation.

Fig 9-28 b Crown on the control model.

Fig 9-28 c Crown on the mobile die.

Fig 9-28 d Final situation: 11 feldspathic crown without internal substructure.

Indications refer to single crowns on the incisors in a functional occlusion. No bridges can be made. The tooth preparation is reduced (as it has no substructure). The amount of removed dental substance depends on the color difference between the tooth and the final restoration.

If the intended color change is within one shade, the preparation of the tooth can be performed as follows: 0.5 to 0.8 mm on the axial surfaces, 1 mm on the incisal margins, and 0.8 mm orally for the anterior guidance.2,3 A very dark tooth shade (tetracycline staining, non-vital teeth, impossible-to-remove metal posts) contraindicates such crowns because they cannot completely hide this discoloration. Cementation is based on adhesion, with a composite resin matching the color of the restoration. This type of ceramic can be etched, and the very good adhesion to the enamel provides clinical durability (Figs 9-28a to 9-28d). 9.3.2 All-ceramic crowns with an internal substructure 9.3.2.1 All-ceramic crowns with an In-Ceram substructure In-Ceram comprises a range of ceramic materials, based on the same principle but having different strengths, translucencies, and manufacturing methods, so as to cover a wide spectrum of clinical indications. There are three variants: • In-Ceram Spinell (magnesium and alumina matrix), with the highest translucency, but with moderate resistance. • In-Ceram Alumina (alumina matrix), with increased resistance and low translucency. • In-Ceram Zirconia (zirconia and alumina matrix), with very high resistance and very low translucency, initially used for posterior, three-unit bridges. The In-Ceram system was developed as an alternative to the conventional porcelain fused to metal (PFM) crown. Its flexural strength varies from 350 MPa for spinell, to 450 MPa for alumina, and to 650 MPa for zirconia.

Fig 9-29 a Initial situation

Fig 9-29 b Final situation

Fig 9-29 c 12, 11, 21, 22: In-Ceram alumina crowns.

Fig 9-29 d Final situation during smiling.

The restoration is made of a ceramic powder and water mixture that is applied with a brush on a duplicate model. Modeling is made in excess because a contraction of about 0.2% will occur during firing. Thereafter, the alumina coping is infiltrated with lanthanum glass that will enter the pores of the porcelain, making it much more resistant. The final step is the layering with feldspathic porcelain.1,2 The indications for this system in the anterior area are single crowns, or three-unit bridges with one intermediate. The internal coping is opaque; masking the intense discoloration but decreasing the crown translucency. This is why the In-Ceram alumina crown is compared with the PFM crown with respect to the umbrella effect (due to the opacity of the internal core) (Figs 9-29a to 9-29d). 9.3.2.2 All-ceramic crowns with a pressed ceramic substructure These crowns have internal copings made through a technical ceramic pressure-injection procedure. The copings are made using the lost-wax technique that is invested; following that, a mold is obtained, into which monochromatic, fused ceramic ingots are injected. After the copings are processed they are covered with layering ceramics that will confer translucency and beauty to the restoration. There are different shades and translucencies of ingots: from high translucency to high opacity, depending on the tooth color. The more discolored the tooth, the higher the opacity of the coping, in order for it to mask the dark shade. Initially, leucite glass ceramics were used (eg, Empress, Ivoclar; Finesse, Dentsply; OPC, Pentron). Currently, lithium disilicate glass ceramics are used (IPS e.max, Ivoclar), which

have an increased flexural strength of up to 360 to 450 MPa. In addition to improved strength, this type of ceramic also has a very good translucency, due to the lithium disilicate particles. The layering ceramic is made of fluorapatite crystals in an aluminosilicate glass.

Fig 9-30 a Initial situation.

Fig 9-30 b 12, 11, 21, 22 Pressed e.max crowns with layering.

There are glass ceramic ingots that are used for the computerized milling procedure (e.max CAD). This procedure increases the accuracy of the marginal fit and maintains the translucency qualities of the ceramics. The indications in the anterior area refer to any teeth, whether they are vital or discolored, or not. Three-unit bridges with one intermediate can also be made, provided that the connector area is 12 to 16 mm².1,2 The advantages of this system combine the marginal fit of the pressed coping (which does not undergo major changes during pressing, unlike feldspathic porcelain which undergoes contraction during firing) with the esthetics of layering porcelain that provides depth of color.

These crowns will be adhesively bonded because these ceramics can be etched. The color of the resin used should be adapted to the color of the tooth and the restoration (Figs 9-30a and 9-30b). 9.3.2.3 All-ceramic crowns with a zirconia substructure These restorations have an inner core made by using the computerized CAD/CAM milling system. There are two high-strength ceramics that can be computer milled: one based on zirconium dioxide (ZnO2) and another on aluminum oxide (Al2O3 – Procera, Nobel Biocare). Zirconia has a much higher flexural strength than alumina, reaching 900 to 1,100 MPa. The technical process involves the obtaining of a model that will be optically scanned. The virtual coping is made using a computer, and information is transmitted to the milling center, where the zirconia block will be milled. Partially sintered (green stage) zirconia blocks are preferred, in order to shorten the milling time and to prevent microfractures. Computerized processing ensures an extremely accurate marginal fit. Studies show that there are no problems related to the zirconia substructure; the difficulties arise from the chipping and cracking of the layering ceramics. A slow cooling protocol when firing the glaze is suggested, in order to equalize the heat dissipation from zirconia to porcelain. This seems to have been shown to increase the porcelain fracture resistance by 20%.

Fig 9-31 a Initial situation: discolored non-vital tooth 12.

Fig 9-31 b Zirconia crown with layering.

Fig 9-32 a Initial situation: 21, 22, porcelain fused to metal crowns and non-vital teeth.

Fig 9-32 b Final situation: zirconia crowns with layering.

There are many indications for this system, including single crowns and extended bridges (exceeding the barrier of one single intermediate), provided a correct area for the connector of about 6 to 9 mm² (which is, in fact, decided by the computer software) is obtained. It can also

be used for extremely stained teeth, even those with metal posts, because zirconia is opaque. Certain clinicians complain about this opacity of the final restoration caused by the zirconia coping, and avoid using the system in the anterior area. However, since zirconia has been on the market, the chromatic properties of the blocks have improved. There is a wide variety of zirconia producers, such as Lava (3M Espe), Everest (Kavo), and CEREC inLab (Sirona).1,2,8 These systems cannot be etched, therefore adhesive cementation is questionable, although manufacturers have tried to produce bonding formulas for zirconia. There are studies that support the need for zirconia sandblasting (eg, the Rocatec 3M Espe system) for a better bonding, but others are against sandblasting because it could cause microfissures. In the absence of a consensus, we suggest a conventional cementation (Figs 9-31a, 9-31b, 9-32a, 932b). To prepare the teeth in the anterior area in order to apply an all-ceramic crown with an internal substructure involves the following requirements:3 • The convex reduction of the buccal surface in a mesiodistal and cervicoincisal direction. • The reduction of this surface is 1 to 1.5 mm. • The oral surface is reduced in two planes: above the cingulum (with a 10 to 22 degrees occlusal convergence angle with the cervical third of the buccal surface), and below the cingulum (a concave area in order to ensure space for anterior guidance). • The reduction of this surface is 1.2 to 1.5 mm. • The proximal surfaces have an occlusal convergence angle of approximately 10 degrees. • The reduction of the incisal edge is 1.5 to 2 mm. • A flat incisal margin is preferred for the support of the ceramics. • Cervical preparation: shoulder with a rounded inner angle or altered chamfer. • The shoulder width is about 1 to 1.2 mm, depending on the tooth size. • The angles and edges are rounded in order to avoid tensions in the ceramics. Durability studies The decision of the clinician and, particularly, of the patient regarding the choice of a certain restoration is influenced by the question: “How long will it last?” This question cannot be answered accurately because in vivo durability is influenced by several variables that do not always depend on the clinician or the manufacturer. We can only quote the published literature referring to in vitro resistance studies and longitudinal clinical studies over different lengths of time.

All articles provide data confirming a very good longevity of these restorations in the oral cavity, provided that the indications are followed and the correct technique is used. By selecting some of the information reported in articles referring to all-ceramic crowns in the anterior area, we found a 15-year success rate of 82.7% for the In-Ceram system, a 7-year success rate of 98.9% for the pressed glass ceramic system, and a 6-year success rate of 88.9% for zirconia. Another analysis performed for the entirety of all-ceramic systems in the anterior area indicates a 10-year success rate of 93.5%, and a 20-year success rate of 78.5%.4-9 This data should give us full confidence in using all-ceramic systems.

REFERENCES 1. Giordano R, McLaren E. Ceramics overview: Classification by microstructure and processing methods. Compend Contin Educ Dent 2010;31:682–696. 2. Fradeani M, Barducci G. Esthetic Rehabilitation in Fixed Prosthodontics: Prosthetic Treatment, vol 2. Chicago: Quintessence, 2008. 3. Massironi D, Pascetta R, Romeo G. Precision In Dental Esthetics. Chicago: Quintessence, 2007. 4. Segal BS. Retrospective assessment of 546 all-ceramic anterior and posterior crowns in a general practice. J Prosthet Dent 2001;85:544–550. 5. Land MF, Hopp CD. Survival rates of all-ceramic systems differ by clinical indication and fabrication method. J Evid Based Dent Pract 2010;10:37–38. 6. Rinke S, Tsigaras A, Huels A, Roediger M. An 18-year retrospective evaluation of glass-infiltrated alumina crowns. Quintessence Int 2011;42:625–633. 7. Beier US, Kapferer I, Dumfahrt H. Clinical long-term evaluation and failure characteristics of 1,335 all-ceramic restorations. Int J Prosthodont 2012;25:70–78. 8. Heintze SD, Rousson V, Survival of zirconia and metal-supported fixed dental prostheses: A systematic review. Int J Prosthodont 2010;23:493–502. 9. Lops D, Mosca D, Casentini P, Ghisolfi M, Romeo E. Prognosis of zirconia ceramic fixed partial dentures: A 7year prospective study. Int J Prosthodont 2012;25:21–23.

9.4 THE CUSTOMIZED ABUTMENT: TECHNIQUE, MATERIAL There are many esthetic challenges when restoring a single central incisor in the anterior area. These are due to the fact that perfect symmetry along the median line should be obtained in the attempt to perfectly mimic nature. This means that adequate size and form, micro- and macrotexture, color, translucency, and brightness must all be found, while including the oral surface in the functional occlusal pattern. In addition to these objectives, one of the greatest challenges will be the junction with the periodontal tissues, which is frequently the Achilles, heel of a restoration. Regarding the gingiva, the following should be obtained: a symmetry of gingival height, buccal gingival convexity, zenith position, interdental papillae length, and a color similar to that of the homologous natural tooth. All this is much more complicated when the restoration in the anterior area is performed not on a tooth but on an implant. This is mainly due to peri-implant tissues. Most frequently, when an implant restoration is required in the anterior area, the available bone is quite limited. The possible negative result may be tissue retraction. In addition to the limited available bone, soft tissues are often deficient; therefore most authors recommend both bone and connective tissue grafting.1-4 For a successful esthetic implant restoration in the anterior area, the following factors should be taken into account: Surgical factors • The correct positioning of the implant in three planes: buccal-oral, mesiodistal, and apicocoronal.4-6 • The use of reduced diameter implants in order to preserve as much bone as possible, particularly towards the buccal cortex.14 • Bone grafting (particularly in the case of postextraction implantation) in order to compensate for the shape and size difference between the root and the implant.1 • Connective tissue grafting to prevent subsequent retraction and to ensure the gingival seal.9 Prosthetic factors • The use of temporary restorations in order to condition peri-implant soft tissues, with the

conformation of the gingival contour and interdental papillae. • The use of customized implant abutments to preserve the shape of the conditioned periimplant tissues. • The use of esthetic materials, both for the customized abutment and for the restorations, to allow light transmission as close as possible to that of dental tissues.8-12 Some studies consider that the constant use of an esthetic abutment is unnecessary. We found the following correlation between the thickness of peri-implant tissues and the choice of a prosthetic abutment: • If the peri-implant tissues are thicker than 3 mm, any type of abutment can be used (made of titanium or ceramic). • If the peri-implant tissues are less than 3 mm thick, ceramic abutments should be used. A dentin color abutment is preferred.5,7 Regardless of the material used for the implant abutment, there are certain requirements related to its design: • A chamfer to adapt the restoration (crown, veneer). • Positioning of the margins 1 mm subgingivally in the anterior buccal area and juxtagingivally in the palatal area. • Emergence profile thick enough for the support of the peri-implant tissues. • Concave profile in the subgingival area in order to preserve the connective tissue graft or the peri-implant soft tissues and to ensure a sufficient thickness of the keratinized tissue.13 Some authors agree that the biotype, the quality, and the thickness of the soft tissues, along with a subcontoured abutment and the type of material, seem to be more important than the buccal thickness of the bone for soft-tissue stability and long-term esthetic results.7,11 9.4.1 Role of the customized abutment The final abutment should have a (transgingival) shape that perfectly replicates the shape of gingival tissues contoured with the provisional restoration. Generally, this transgingival shape is concave to avoid any pressure on the soft tissues and to prevent subsequent retraction. In addition, this concave shape will preserve the adequate thickness of the soft tissues, which have probably already been grafted.9,12 The use of prefabricated definitive abutments on which a (generally horizontal) shoulder

will be milled, and which have an inadequate diameter (in general too large, being correlated only with the implant diameter) will cause the unexpected, sometimes instant, retraction of the peri-implant soft tissues, with an inadequate esthetic result (Figs 9-33 to 9-36).3

Fig 9-33 Contouring the soft tissues using provisional restorations.

Fig 9-34 Use of a prefabricated abutment inadequate for the requirements of the peri-implant soft tissues.

Fig 9-35 Use of a prefabricated abutment inadequate for the requirements of the peri-implant soft tissues.

Fig 9-36 Retraction of the peri-implant soft tissues after the placing of a non-customized abutment.

Fig 9-37 Temporary abutment in place immediately after surgery.

Fig 9-38 Temporary crown in place.

Fig 9-39 Reshaping of the temporary crown and abutment for the soft tissue conditioning.

Fig 9-40 The final assembly.

9.4.2 The technique of the fabrication of the customized abutment • It is recommended to place a temporary abutment and a temporary – acrylic or composite – crown similar to the neighboring tooth (if there is a primary stability of the implant – immediate loading). These are formed either by milling or by the addition of acrylic/composite material until the desired shape of the peri-implant soft tissues is obtained (Figs 9-37 to 9-40). • After the osteointegration of the implant and once the soft tissues are stable, final restoration is performed. For this, an impression of the transgingival path of the peri-implant soft tissues should be made in order to obtain the customized abutment (Figs 9-41 and 9-42). • The temporary abutment and crown are removed. The temporary abutment is screwed on an implant analog. • This ensemble is inserted into an impression material (preferably silicone putty), leaving only the supragingival part of the temporary crown at the surface (Figs 9-43 and 9-44).

Fig 9-41 Four months after surgery.

Fig 9-42 Profile of the peri-implant tissues conditioned by temporary restorations.

Fig 9-43 The temporary abutment and crown before their placement in the implant analog.

Fig 9-44 Silicone putty impression.

Fig 9-45 Impression of the transgingival area.

Fig 9-46 Acrylic resin applied on the impression coping.

• Once the impression material has completely hardened, the temporary abutment and crown are removed from the implant analog. Thus, the impression of the transgingival area to be replicated is left in the silicone.

• An impression coping is placed in the implant analog on which self-curing acrylic resin will be applied, for the impression of the transgingival area (Figs 9-45 and 9-46). • After the resin has set, the transfer abutment (impression coping) with the acrylic resin is removed and screwed into the implant in the oral cavity. It is extremely important at this time that the acrylic resin exerts no pressure on the peri-implant soft tissues. If pressure is obvious (ischemic tissues), immediate adjustment of the acrylate should be performed (Figs 9-47 and 9-48). • Finally, after insertion, an individual open tray impression is made using silicone/polyether (Fig 9-49). An impression of the peri-implant tissues after conditioning by the provisional restoration can be made using a flowable light-curing resin. The resin is applied on the impression coping and light-cured in the oral cavity, thus duplicating the form of the soft tissues. After the lightcuring, a classical impression (polyether or polyvinylsiloxane) in an open tray can be made (Figs 9-50 to 9-52).

Fig 9-47 Mock-up of the transgingival area.

Fig 9-48 Placement of the transfer abutment in the oral cavity without tissue ischemia.

Fig 9-49 Open tray impression with polyether.

Fig 9-50 Peri-implant tissues conditioned by the provisional restoration.

Fig 9-51 Light-cure resin applied on the impression coping.

Fig 9-52 Open-tray impression.

In the laboratory, a model will be made that will accurately replicate the shape of the periimplant tissues. The technical modality for making the abutments subsequently depends on the materials used. In general, these abutments are hybrid, with a (prefabricated) titanium core, over which a zirconia or pressed ceramic coping is applied. If a hybrid-zirconia abutment is required (Figs 9-53 and Fig 9-54), the model is scanned; thereafter, the zirconia coping is CAD/CAM milled and subsequently cemented to the titanium core. Before bonding, a very thin porcelain layer (glaze) will be fired on the zirconia abutment to ensure the adhesive cementation of the future all-ceramic crown. Bonding on zirconia is still questionable. If a hybrid pressed porcelain abutment is required, the coping will be waxed on the titanium core. The coping will be invested and a suitable coloured ceramic ingot will be pressed into the mold. Subsequently, it will be bonded to the metal. Generally, in this situation, the final restorations are adhesively cemented to the abutment.

Fig 9-53 Customized abutment (hybrid e.max) replicating the conditioned peri-implant tissues applied in the implant.

Fig 9-54 Hybrid zirconia abutment.

Fig 9-55 Components of a hybrid e.max abutment before bonding.

Fig 9-56 Hybrid e.max abutment in place.

Fig 9-57 Monolithic e.max screw-retained crown (the buccal surface will be covered with a porcelain veneer to hide the screw area).

Fig 9-58 Application of pink composite resin to mask potential retraction.

There are various implant systems that have prefabricated metal abutments allowing for the direct pressing of the porcelain without the need for the subsequent bonding of the coping. This

is the case with the screw-retained crown; the coping can have the shape of the final crown. This crown will only be painted on the surface, with a cut-back area at incisal level. This type of construction has the advantage of the absence of residual cement in the sulcus, which might, in time, cause peri-implantitis.12,14 Sometimes, below the shoulder, at transgingival level, the porcelain can be painted pink, or pink composite resin similar to gingival tissues can be applied. This is aimed at optically masking a potential subsequent gingival retraction (Figs 9-55 to 9-58).4 In conclusion, in order to obtain esthetic results with implant restorations in the anterior area, the literature recommends taking into consideration a number of requirements related to the implant abutment:3,4,9,15 • A subcontoured or concave abutment. • Abutment materials that are as compatible as possible: zirconia, alumina, titanium. • Avoidance of multiple screwing and unscrewing procedures, and the early placement of the final abutment. • Development of the contour of soft tissues using the provisional restoration and the final impression with the abutment in situ. • Zirconia has a small degree of accumulation of bacteria. • The cleaning and disinfection of the abutment is essential in order to obtain a good tissue response.

REFERENCES 1. Botticelli D, Berglundh T, Lindhe J. Hard-tissue alterations following immediate implant placement in extraction sites. J Clin Periodontol 2004;31:820–828. 2. Higginbottom F, Belser U, Jones J, Keith S. Prosthetic management of implants in the esthetic zone. Int J Oral Maxillofac Implants 2004;19:62–72. 3. Kois JC. Predictable single-tooth peri-implant esthetics: Five diagnostic keys. Compend Contin Educ Dent 2004:25:585. 4. Saadoun AP, Sullivan DY, Krischek M, le Gall M. Single tooth implant: Management for success. Pract Periodontics Aesthet Dent 1994;6:73–80. 5. Belser U, Martin W, Jung R, et al. ITI Treatment Guide. Vol 1: Implant Therapy in the Esthetic Zone: SingleTooth Replacements. Chicago: Quintessence, 2007. 6. Tarnow DP, Elian N, et al. Vertical distance from the crest of bone to the height of the interproximal papilla between adjacent implants. J Periodontol 2003;74:1785–1788. 7. Kois JC, Kan JY. Predictable peri-implant gingival aesthetics: Surgical and prosthodontic rationales. Pract Proced Aesthet Dent 2001;13:691–698, 721–722. 8. Misch C. Dental Implant Prosthetics. St Louis: Mosby, 2005. 9. Fradeani M, Barducci G. Esthetic Rehabilitation in Fixed prosthodontics. Vol 2: Prosthetic Treatment: A Systematic Approach to Esthetic, Biologic, and Functional Integration. Chicago: Quintessence, 2007. 10. Jemt T. Restoring the gingival contour by means of provisional resin crowns after single-implant treatment. Int J Periodontics Restorative Dent 1999;19:20–29. 11. Canullo L, Pace F, Coelho P, Sciubba E, Vozza I. The influence of platform switching on the biomechanical aspects of the implant-abutment system. A three dimensional finite element study. Med Oral Pathol Oral Cir Bucal 2011;16:e852–e856. 12. Canullo L, Iannello G, Netuschil L, Jepsen S. Platform switching and matrix metalloproteinase-8 levels in periimplant sulcular fluid. Clin Oral Implants Res 2011;23:556–559. 13. Giannopoulou C, Bernard JP, Buser D, Carrel A, Belser UC. Effect of intracrevicular restoration margins on peri-implant health: Clinical, biochemical, and micro-biologic findings around esthetic implants up to 9 years. Int J Oral Maxillofac Implants 2003;18:173–181. 14. Mustafa K, Wennerberg A, Arvidson K, Haag P, Karlsson S. Influence of modifying and veneering the surface of ceramic abutments on cellular and proliferation. Clin Oral Implants Res 2009;19:1178–1187. 15. Proceedings of the Third ITI Consensus Conference. Int J Oral Maxillofac Implants 2004;19(suppl):1–156.

(10.1) CONSTANTIN VÂRLAN, BOGDAN DIMITRIU, IONUŢ BRÂNZAN (10.2) CAMELIA ALB, FLORIN ALB (10.3) SMARANDA BUDURU, RAREŞ BUDURU

Chapter X ESTHETIC RESTORATION OF POSTERIOR TEETH

10.1 DIRECT RESTORATIONS In their most recent variants, ie, based on microhybrid, submicrohybrid, nanofilled, and nanotechnology, composite resins are extremely widely used for restoring posterior teeth, due to their adequate biomechanical and esthetic properties.2–9 For these restorations, composite resins can be used by means of several techniques based on enamel-dentin adhesion:2,7 • Direct. • Semi-direct. • Direct – Indirect. • Indirect. Direct techniques are the best known and most widely used. Improved and diversified enamel-dentin adhesive systems, along with compensated polymerization shrinkage to counteract and balance undesired side effects, may currently provide a high-quality marginal adaptation, with good longevity, without microleakage.2,3,6,7 Current composite resins have superior physical and chemical properties that have increased their fracture and wear resistance, so that this problem is practically solved, at least for restorations of cavities with small and medium extension.4,5,8,9 The result of these improvements is that direct esthetic restorations with composite materials have proved to have a higher survival rate.4,5,7–9 The problems concerning the quality of direct restorations are related to their use in large and deep cavities, or in cavities that are difficult to access in order to apply the appropriate handling technique. These problems are related to the maintenance of the marginal adaptation to cavity contour areas located at the limit of the cementoenamel junction (CEJ), or beyond it, or to the presence of excessively undermined or fragile enamel crown walls. In such situations, restoration possibilities other than direct adhesive composite techniques should be considered.1,2,4,5,7–9 In 1998, the American Dental Association defined a series of indications regarding the esthetic restorations of posterior teeth using direct adhesive techniques:4,5,7 • Sealing, even extended sealing, of pits and fissures. • Preventive resin restorations in pits and fissure areas. • Treatment of primary class I and class II caries lesions.

• Treatment of secondary caries lesions in class I and class II restorations, when the buccaloral extension of the cavity is smaller than half the distance between the buccal and the oral cusps. • Treatment of class V cervical lesions. • Patients allergic to metal alloy restorative dental materials.

Fig 10-1 a Preoperative situation of 17. Old restoration with incorrect marginal adaptation.

Fig 10-1 b A class I occlusal cavity on 17 (beveled preparation).

10.1.1 Adhesive preparation The adhesive preparation7 is indicated in primary cavitated caries lesions, the size of which is exclusively determined by the extent of the missing hard dental tissues. The specific aspects of an adhesive restoration in such cases consist of rounded internal angles of the cavity and a chamfer preparation of its enamel margins. It should be noted that due to the orientation of the enamel prisms at the external margins of the cavity, their finishing by using adequate rotary cutting instruments (straight fissure, tapered fissure, or flame finishing

burs) perpendicular to the occlusal surface results in sectioning of the prisms, and in exposing the cut surface under a favorable angle for acid etching. Therefore, there is no longer the need for conventional beveling at this level.3,6,8 10.1.2 Conventional preparation with beveled margins In clinical situations characterized by the existence of a previous metal alloy restoration, a conventional preparation with beveled margins becomes necessary. After the removal of the metal alloy restoration and of the irreversibly altered hard dental tissues, this preparation of the cavity consists of adjusting by rounding the internal angles and finishing the beveled external margins, most preferred as a chamfer. These changes to the initial preparation result in a cavity (Figs 10-1a and 10-1b) with adhesive characteristics.2,7,8 10.1.3 Restorative materials In most cases, the restorative materials indicated for the posterior teeth are the microhybrid composite materials, having an average microparticle size of 0.5 to 1 µm, and pyrolytic silica particles of 0.04 µm. Flowable composite materials are frequently applied, as a first increment, on the floor or on the pulpal walls of occlusal or proximal cavities. The continuing evolution of direct restoration materials has determined the development and use of composite materials intended for lesions located in posterior teeth, including nanoparticles with sizes generally smaller than 100 nm (most frequently ranging between 5 and 20 nm). These materials are characterized not only by the nanometric size of the particles they are loaded with, but also by specific nanotechnological modalities, which allow the stable grouping of nanoparticles in clusters with sizes similar to those of microparticles: 1 to 5 µm, up to 10 µm. Thus, the mineral filling of such a composite material consists of both separate nanoparticles and nanoclusters. At the same time, these technological improvements have allowed the production of materials with a higher degree of particle loading, both in weight (70% to 80%) and in volume (60% to 65%). Due to all these changes, current composite materials recommended for posterior teeth have very good physical (particularly mechanical) properties. These translate into the obtaining of a wear resistance similar to enamel and silver amalgam (10 to 50 µm/year).3,6,9 The presence of an elasticity modulus close to that of dentin results in mechanical strain responses similar to those of dentin and significantly contributes to the integration of the

direct restoration in the stress behavior of the tooth concerned. The esthetic result is also remarkable. This is due, first of all, to the special finishing and polishing possibilities resulting from the optimal surface characteristics of the latest generation of composite materials. Furthermore, there are currently not only many different shades available, but also different degrees of translucency. These are the result of the mixture of particles with different optical properties, both in the material mass (as separate nanoparticles) and inside the nanoclusters. The protocol for a composite restoration of the posterior teeth recommends the use of flowable resin composites, with a lower elasticity modulus, of maximum 5 GPa, applied to the cavity floor, over the enamel-dentin adhesive. These belong to microhybrid composites with a higher internal flowability, and show a higher elasticity in comparison with dentin (18 GPa). They are applied in a thin layer, as the first increment, between the adhesive system and the composite material that will represent the bulk of the final restoration. The use of flowable composite materials is indicated for: • Improving the interface between the adhesive system layer found on the cavity floor and the composite material that forms the main mass of the restoration. • Compensating internal stress that occurs during polymerization and is manifest by the shrinkage of the material, consequently by tension exerted on the internal walls of the cavity. • Diminishing the risk of postoperative sensitivity, which manifests particularly in the case of an unfavorable configuration of the cavity. From this point of view, the cavity is evaluated by assessing the C factor.4,5,7,8 This permits the estimation of the ratio between the elements that define the configuration of the cavity and the value of stress developed due to the polymerization shrinkage. The C factor takes into consideration the number of cavity surfaces with or without adhesion, thus describing the relationship between the number of the cavity walls, the number of adhesive interfaces, and the polymerization shrinkage. Thus, the risk of the weakening of adhesion is determined by the increase of the polymerization shrinkage values, the condition of a higher number of cavity surfaces, and the use of a composite resin material with a higher consistency. It is estimated that the polymerization shrinkage value is minimum in the case of a freely flowing material, and consequently, the number of free surfaces without an adhesive interface is higher than that of the adhesion surfaces involved in the restoration.7 Thus, it becomes obvious that the composite material has a limited flow in the case of class

I and V cavities, which are characterized by an unfavorable C factor, due to the existence of five surfaces presenting adhesive interfaces and only one free surface. In these situations, the direct consequence is an increase of internal stress occurring during the polymerization shrinkage, and consequently, a lowering of the chances for the maintenance of adhesion between the composite restoration material and the hard dental tissues. Thus, the use of flowable composite materials as an intermediate layer between the adhesive system found on the cavity floor and the restoration material becomes a necessity because of the possibility offered by the intrinsic characteristics and the behavior of these materials, which counteract the internal tensions caused by the polymerization shrinkage.3–7 10.1.4 Placement and shaping of the material – layering The placement techniques for composite materials are aimed both at compensating the subsequent tendency of detachment from the cavity walls, caused by polymerization shrinkage, and facilitating the shaping and obtaining of the desired shades in the chromatic context of the teeth concerned. The chromatic characteristics specific for posterior teeth generally make the selection of the colors of the composite material easier than for anterior teeth,2,10 and many manufacturers reduce the number of basic shades in the composite material kits concerned. A tendency to consider a single shade for dentin and a few shades for enamel can be observed.7–9 Establishing the color and shade details of the dental surfaces to be restored is recommended by assessing these aspects before isolation with a rubber dam, both at the level of the tooth concerned and of the neighboring and the contralateral tooth. It should be noted that the shade of the material layer that will replace the dentin must be evaluated not only regarding the type of tooth, but also the age of the patient, which can significantly contribute to the alteration of tooth color. The chromatic appearance of the material layer intended for the replacement of the enamel should take into consideration the characteristics of natural enamel, with a higher opalescence and brightness, obviously also depending on its thickness at the level of the different anatomy elements of the tooth-crown surfaces. Taking this into account, whiter shades are recommended for the restoration of enamel crests, and the use of pigments to evidence occlusal fissures and pits.7–9 Regarding the modalities of placement of the composite material for direct restorations of posterior teeth, there are several techniques depending on the size of the cavities to be

restored, represented by the bulk application of the composite material, the horizontal layering technique, the oblique layering technique, the three-increment technique, and the four-increment technique. 10.1.4.1 The bulk placement of composite resin material This is a modality recommended for small-size cavities, the so-called “preventive cavities”. In these situations, the reduced thickness of the composite material required for the restoration allows the curing shrinkage value to be assessed as being practically insignificant,2,7 and consequently, it permits the placement and polymerization of the material inside the entire cavity from the start. 10.1.4.2 The horizontal layering technique The layer replacing the dentin is placed first, while respecting the shade and thickness of the dentin mass, as well as the cusp slopes and the appearance and depth of occlusal pits and fissures. Allowing enough space for the placement of the enamel-replacing layer, 0.5 to 1 mm thick, should be considered. Its placement and shaping should be according to the specific aspects for the tooth anatomy.

Fig 10-2 Horizontal layering on 27.

Fig 10-3 a–c Oblique layering on 27.

Fig 10-4 a, b Final appearance of the restoration.

Horizontal layering (Fig 10-2) with light curing from the direction of the cavity access opening is an adequate technique for deeper cavities with a smaller surface extension.2,7 10.1.4.3 The oblique layering technique Larger-size cavities, with an extended surface and a depth estimated as medium to high, require placement and light curing in successive layers, due to a higher amount of composite material that will be applied, which increases the risk of internal tensions caused by the polymerization shrinkage. The use of horizontal layering techniques in these cases would allow for the development of important tensions, exerted on the opposite walls of that cavity.2,7–9 Although it is considered that the positioning of the light beam can affect the action direction of vectors according to which the polymerization shrinkage manifests, the elements that decisively influence the behavior of the restoration material during polymerization are the shape of the cavity and the value of adhesion. Therefore, the guidance of the light beam for curing through the cusp thickness can contribute to the orientation of shrinkage vectors towards

the walls, not to the center of the cavity (although this is not an essential factor). However, the shaping of the composite material can be facilitated by its placement using the oblique layering technique (Figs 10-3a, 10-3b, 10-3c, 10-4a, and 10-b), and trans-cusp light curing can be progressive (soft-start), which can contribute to the lowering of the polymerization shrinkage value of the resin composite and, implicitly, of the internal stress acting upon the cavity walls. 10.1.4.4 The three-increment technique This modality of placing resin composite materials has been more recently indicated by some authors7–9 for small- and medium-size class I cavities. The three increments are represented by: • The application of a flowable composite layer to cover the dentin adhesive system found on the cavity floor. • The placement of the composite material replacing the dentin in one layer. • The placement of the composite material replacing the enamel in one layer, and its shaping at occlusal level. 10.1.4.5 The four-increment technique This technique, even more recently indicated by a number of authors,7–9 for small- and mediumsize class II cavities, is performed as follows: • Placement of an enamel layer adjacent to the matrix, which will restore the missing proximal wall and the marginal ridge (conversion of a class II cavity into a class I cavity: the centripetal technique). • Placement of the flowable composite for the covering of dentin on the cavity floor. • Placement of the dentin mass in one layer. • Placement of the enamel mass in one layer and occlusal shaping. 10.1.5 Finishing and polishing By following the principles and the technical steps of the layering and occlusal shaping of the resin composite, a restoration that does not require occlusal adjustments can be achieved. Taking into consideration the occlusal anatomy (pits and fissures, cuspal slopes) during the placement steps, practitioners can avoid marginal gaps or material overhangs beyond the limits of the cavity. The need for post-curing contouring on the visible surfaces of the restoration is

thus significantly reduced, which results in the absence of special finishing and polishing problems, particularly in class I cavities. Potential intervention areas are usually found at the tooth-restoration interface. The rest of the exposed surface of the restoration is only polished with rubber points with little or no abrasion, with the brushes impregnated with polishing paste. In this way, the finishing and polishing steps take very little time and are also aided by the high esthetic qualities of current composite resin materials.2,4,5,7–9 10.1.6 Clinical technique step-by-step 10.1.6.1 Isolation of the operating field • Recording of occlusal contacts, anesthesia, and placement of the rubber dam. • Cleaning of dental surfaces by using powder jet devices (bicarbonate, pumice stone powder, etc), with small-size prophylactic cups. 10.1.6.2 Cavity preparation and finishing • Removal of pre-existing (metal or metal-free) restorations with adequate rotary instruments, at high speed.

Fig 10-5 a Enamel etching.

Fig 10-5 b Dentin etching.

Fig 10-5 c Rinsing for 30 to 60 seconds.

• Preparation of the cavity with cylindrical or spherical fine diamond burs, mounted in the reduction contra-angle handpiece – red ring. • Removal of the infected dentin with steel or carbide burs, mounted in the contra-angle handpiece – blue ring. • Finishing of margins: beveling and finishing of the enamel with cylindrical fine burs or flame burs, mounted in the reduction contra-angle handpiece – red ring. 10.1.6.3 Enamel and dentin adhesion procedures • Enamel and dentin etching (total etch), with 35% to 37% phosphoric acid (20 to 40 seconds for enamel, 10 to 20 seconds for dentin) (Figs 10-5a and 10-5b). • Rinsing with water up to 30 to 60 seconds (Fig 10-5c) and gentle air drying to remove all humidity traces from the rubber dam sheet and the neighboring teeth, avoiding the penetration of the air jet straight inside the cavity in order to prevent tissue dehydration; after etching and

rinsing and before the primer application, the application inside the cavity for 1 to 2 minutes of a 0.2% to 2% chlorhexidine solution, with antimicrobial and protease (MMPs) inhibitor role, has also been suggested.5 • Abundant application of the primer, by persistent rubbing against the dentinal walls for 30 to 60 seconds, with the frequent addition of new amounts of primer. • Gentle air drying for 5 to 10 seconds; after drying, the surface should be glossy and bright. • Application of the bonding resin on the enamel and dentin walls by rubbing for several seconds, forming a layer that is subsequently extended and reduced in thickness, using a gentle air jet. • Light curing of the adhesive for 20 to 40 seconds. • Application and light curing of a flowable resin composite layer on the cavity floor.

Fig 10-6 View during dentin layering for an occlusal restoration on tooth 37.

Fig 10-7 View after enamel layering for an occlusal restoration on tooth 37.

Fig 10-8 a View after tint application on tooth 37.

Fig 10-8 b Final view after finishing and polishing of the occlusal restoration.

10.1.6.4 Layering of the dentin composite mass • Horizontal layering in narrow and deep cavities and progressive (soft-start) direct or usual light curing. • Oblique layering and trans-cusp light curing (with additional occlusal light beam) in large cavities. • Multiple increment layering according to anatomical principles, and shaping of cusp slopes and occlusal pits and fissures (Fig 10-6). • Light curing of each composite increment.7 10.1.6.5 Layering of the enamel composite mass • The bulk technique is applied for small-size cavities. • Horizontal and oblique anatomical layering is used for larger cavities. • The characterization of pits and fissures is performed.

• The different composite layers are light cured; at the last activation, the application of a fine glycerin gel layer in order to block the inhibitory effect of atmospheric oxygen and to allow the complete polymerization of the composite restoration surface is recommended. • Mild finishing with fine and extra-fine diamond burs mounted in the reduction contra-angle handpiece – red ring. • Polishing with medium and fine rubber points/cups and silicone polishers. • Polishing with nylon and silicone brushes, together with polishing pastes. • Removal of the rubber dam isolation, checking of occlusal contacts, and final control of the restoration (Figs 10-7, 10-8a, and 10-8b). 10.1.7 Characteristic aspects of direct restorations of posterior teeth in class II cavities There are a number of characteristic aspects of direct restorations in class II cavities, which influence the indications, the techniques for the compensation of the polymerization shrinkage, the instruments and materials required for a correct restoration, and the sequence of operations used for the restoration.2,4,5,7–9 Some of these aspects will be outlined briefly, as follows. These are the main indications for cavities with a small to medium extension, with the maintenance of an adequate enamel layer at the level of the cervical wall of the proximal cavity.2,4,5,7–9 Class II restorations should meet two essential clinical requirements:2,4,5,7–9 • Counteracting the effects of the polymerization shrinkage. • The esthetic anatomical restoration of the concerned teeth. The effects of the polymerization shrinkage, related to consecutive internal stress developed in the tooth-restoration unit, are mainly evidenced by two aspects: • At the level of the cavity walls, through the tendency to deformation by tension, with the possible appearance of microfissures, followed by the partial or total fracture of some walls. • At the level of the adhesive interface, in two areas: – The external margins of the restoration, with the possible appearance of microleakage. – The internal dentinal surfaces, with the possible appearance of postoperative hypersensitivity, by hydrodynamic mechanisms.4,5 The possible effects of the polymerization shrinkage are not immediately clinically evidenced in all cases, but can appear subsequently, after a latency period of several days or

weeks (postoperative sensitivity), or even months (fissures or fractures). The polymerization shrinkage is inherent and is correlated with three main factors:2,3,6–8 • The physical and chemical properties of composite resins. • The adhesion force developed at the tooth-restoration adhesive interface. • The three-dimensional configuration of the cavity and the consecutive C factor. For the compensation of the polymerization shrinkage and the counteracting of its effects, different clinical approaches of direct composite restoration have been proposed: • Application of special tips (Light-tip), with a condensation-polymerization role, at the end of the optical fiber guide of the curing unit.2,7 • The use of prefabricated ceramic inserts, incorporated in the composite resin mass, before polymerization, in order to reduce the volume of material subjected to shrinkage.2,7 NOTE: The two above-mentioned methods have a number of drawbacks: • It is difficult to avoid the placement of excess material at the level of the marginal ridge, with real problems in correctly obtaining the interproximal contact point. • It is difficult to obtain the correct natural shape and color of the restored tooth. • The finishing and polishing procedures become more complicated. • The total working time is prolonged. It is for the above reasons that these methods are practically impossible to use in current practice and are used only in exceptional situations.

The use of multiple layer placement and polymerization techniques, various application sequences, various three-dimensional spatial positioning, and various orientations of the light beam (horizontal technique, three-direction polymerization technique, oblique technique, threeincrement technique, four-increment technique – centripetal technique) seems to be the most adequate approach, according to most opinions.2,4,5,7–9 For the esthetic anatomical restoration of posterior teeth by direct techniques in class II cavities, another important aspect is represented by the necessary instruments and accessories. In addition to adequate instruments for the placement and shaping of composite resin, a

decisive role for the quality of these restorations is played by dental matrices, along with interdental wedges, through their correct use.4,5,7,8 For the restoration of the proximal contour and obtaining the proximal interdental contact, partial matrices (half-matrices) with the double convexity of the matrix band in buccal-oral and occlusal-cervical direction are recommended. They are accompanied by an elastic metal ring which accomplishes a double role: maintaining the matrix in position (similarly to classical matrix holders) and minimally separating the teeth (within physiological limits of the marginal periodontium), in order to obtain the contact point. These types of matrices were specifically designed for direct adhesive composite restorations. The best known and most widely used matrices are:17 • The Palodent matrix system, with Bi-Tine rings. • Silver Plus G rings; the rings of this system have two variants: with long or short interdental arms. • The Composi-Tight GDS 3D matrix system, with Soft Face 3D rings; the rings of this system have three-dimensionally modeled extremities of the interdental arms, following the morphology of the interdental embrasure, by means of attached elastic silicone tips). • The V-Ring matrix system with attached rings. Mesio-occlusodistal cavities require circular (circumferential) matrices, starting from the classical Tofflemire type. The AutoMatrix type is widely used for these types of cavities. It can be introduced, adapted, and maintained in position with optimal results for the final quality of the restoration.

REFERENCES 1. Garber DA, Goldstein RE. Porcelain and Composite Inlays and Onlays: Esthetic Posterior Restorations. Chicago: Quintessence, 1994. 2. Dietschi D, Spreafico R. Adhesive Metal-Free Restorations: Current Concepts for the Esthetic Treatment of Posterior Teeth. Chicago: Quintessence, 1997. 3. Powers JM, Sakaguchi RL. Craig’s Restorative Dental Materials, ed 12. St Louis: Mosby Elsevier, 2006. 4. Hilton TJ, Ferracane JL, Broome JC. Summit’s Fundamentals of Operative Dentistry: A Contemporary Approach, ed 4. Chicago: Quintessence, 2013. 5. Heymann HO, Swift EJ Jr, Ritter VA. Sturdevant’s Art and Science of Operative Dentistry, ed 6. St Louis: Mosby Elsevier, 2013. 6. O’Brien WJ. Dental Materials and their Selection, ed 4. Chicago: Quintessence, 2008. 7. Brenna F, Breschi L, Cavalli G. Restorative Dentistry: Treatment Procedures and Future Prospects. St Louis: Elsevier Mosby, 2009. 8. Mangani F, Putignano A, Cerutti A. Guidelines for Adhesive Dentistry: The Key to Success. Chicago: Quintessence, 2009. 9. Terry DA, Leinfelder KF, Geller W. Aesthetic and Restorative Dentistry: Material Selection and Technique. Houston: Everest Publishing Media, 2011.

10.2 INDIRECT RESTORATIONS 10.2.1 Why a chapter on inlays and onlays in a book of esthetic dentistry? Thirty years ago, if a patient needed a restoration on posterior teeth that was less extensive than a crown, s/he had to choose between a direct amalgam filling and an indirect gold filling. Today, tooth-colored materials are available – such as porcelain and composites – that can be successfully applied in esthetic restorations on posterior teeth because they meet both the esthetic and the functional requirements, simultaneously. Nowadays, the esthetic appearance no longer needs to be sacrificed in favor of an increased mechanical strength, as was the case in the past.1 Studies in recent literature indicate a 10-year success rate of composite and ceramic inlays higher than 90%, which is close to the gold standard, being the noble alloy inlays that are among the most successful and long-lasting indirect restorations.2–4 In 2008 alone, more than 40 million crowns were placed in the United States; many of these treated teeth could have benefited from a more conservative treatment. In the case of preexisting restorations, the preparation for a crown will require the removal of the healthy tissue left on the buccal and oral surfaces, making this a damaging preparation. However, dentists and patients frequently choose crowns because they also seek an improvement in the patient’s appearance on the labial surface, or they have to apply bridges in periodontal disease for the protection of cracked teeth, or for the restoration of the vertical dimension of occlusion.5 10.2.2 What are inlays and onlays, and when should they be applied? An inlay is an indirect restoration made of metal, porcelain, or composite resin, which does not support and does not replace a cusp/cusps. In other words, it restores the dental structure that results following a specific preparation involving only the negative morphology of the tooth (pit, fissures, and grooves). However, the inlay does not ensure protection for a cusp during the lateral and protrusive movements of the masticatory cycle.6,7 An onlay is an indirect restoration that restores the cavity which results from a specific preparation involving both the positive (cusps, tooth surfaces) and the negative (pit, fissures, grooves) morphology on the tooth. It is made of biocompatible materials using various technologies. The onlay most frequently replaces the tips of the cusp/cusps, so it is used to maintain and/or to restore the vertical dimension of occlusion. Most of the occlusal stops in all

functional positions will be created on the restorative material, rather than on the dental structure of the cusps covered by the preparation.8,9 Overlays are indirect restorations made of ceramic or composite, which alter the shape of the tooth without the need for a specific preparation. They may involve both the negative (pit, fissures, and grooves) and the positive (cusps, tooth surfaces) morphology.10

Fig 10-9 Ceramic inlays

Fig 10-10 Pressed ceramic overlays - IPS e.max Press (Ivoclar).

Twenty years ago, indirect restorations were used less frequently than metal-ceramic crowns. Today, with the introduction of new pressing technologies for ceramic, the improved properties of laboratory composites, the evolution of CAD/CAM technology, and the improvement of adhesion to dentin, this situation has been reversed. Nowadays, an increasing number of patients and dentists wish to avoid the extensive preparation required for crowns, and embrace the new trend of minimally invasive dentistry, requesting or easily accepting adhesively bonded esthetic restorations.11,12

The general indications for inlays/onlays are: • Restoration of the damaged tooth structure in cases where direct fillings are no longer possible. • In moderate to extensive enamel loss, when there are difficulties in restoring the contact point. • Mesial retainer for short-span adhesive bridges. • For patients who are resilient to caries attack, with good oral hygiene.13 • For patients with high esthetic demands, when several restorations need to be made in the same dental quadrant; this could be done by taking only one impression. Non-vital teeth that require cusp covering can be treated with an onlay. Teeth with an increased risk of fracture, or “cracked tooth syndrome”, in which cracks are already present and might run deeper if the preparation were limited to the shape of an inlay, will be prepared for an onlay or a crown.14 Corrections of the occlusal plane and the restoration of the vertical dimension of occlusion (VDO) can be prepared with onlays. Relative contraindications include: • Patients with high risk for caries, with bad oral hygiene. • Young patients with a large pulp chamber. • Non-vital teeth: for inlays – teeth with large cervical fillings; for onlays – small-size restorations. • Lack of patient cooperation. The follow-up of these restorations is mandatory. The advantages of indirect restorations on posterior teeth, when compared with direct composite restorations, include the preservation of dental tissues and a higher longevity. Indirect restorations made of gold, composites, or modern ceramics have excellent mechanical and physical characteristics: they can successfully maintain the VDO; they do not cause opposing teeth abrasion; and they do not wear down in time.15,16 Some disadvantages include: a higher cost due to the laboratory fees; their fabrication is longer compared to the direct techniques because they generally involve two appointments (except for the in-office CAD/CAM fabricated inlays and onlays, which can be obtained in one clinical appointment). Ceramic restorations are demanding in terms of technology, while composite restorations are more time-consuming. As retainers, they provide a very low retention in fixed bridges. However, they can only be used for patients with very good oral

hygiene, and for those who come back for follow-ups, because they are restorations with a high risk of secondary caries.17,18 10.2.3 Step-by-step fabrication of indirect inlay/onlay restorations After dentist and patient have agreed to an inlay or onlay as an indirect restoration of choice, the following details will be carefully checked: • Tooth vitality, both clinically and on radiographs, because the preparation will be different depending on this factor. It is known that non-vital teeth have a high fracture risk, and more tooth structure is necessary for the protection of the remaining dental tissue. It is recommended to use the fiber-post reconstructions (based on quartz or glass-fiber posts with a dual-curing composite resin), because the adhesive forces between the luting resin cement and the dualcuring composite in the fiber-post reconstruction is better than the adhesion to a glass-ionomer (GI) cement reconstruction.

Fig 10-11 a A detail of the amalgam filling on tooth 1.6.

Fig 10-11 b Detail of the first dental arch quadrant, after the removal of the old fillings on teeth 1.4, 1.6, and cleaning of the decayed tooth structure on tooth 1.5.

Fig 10-11 c An occlusal detail of the decay depth on teeth 1.4 and 1.6, for which inlays were recommended. For tooth 1.5, a direct composite filling was performed.

Probing the periodontal pockets is extremely important because their presence or absence will determine a different design of the interdental contact point between the inlay/onlay and the neighboring tooth.17,18 The evaluation of the occlusal relationships is mandatory for a low-risk and long-life indirect reconstruction. It is recommended that a bonding layer be applied on the occlusal surfaces after marking the contact points with articulation paper, in order to avoid washing off the markings during tooth preparation with the water-cooling jet. The extension of the preparation for ceramic and composite inlays and onlays is limited to a minimum. It is always better to maintain occlusal contact points in the enamel, and when the cusps are undermined, to include them in the preparation for an onlay, or to use a GI cement for their support. Tooth enamel is the best material for the occlusal function due to its prismatic structure, which transmits occlusal stress correctly.17,18

Ceramic inlays require a more extensive preparation than composite inlays because dental ceramic is a very rigid material and the fracture risk of residual cusps is higher. Due to adhesive bonding and to the elasticity of the resin cement, it is considered that the composite inlay after bonding strengthens the residual cusps.20,21 The biomimetic principle – avoiding any preventive extensions during the preparation – is extremely important because such extensions will decrease the already weakened resistance of the tooth. No restorative material is better than tooth enamel or dentin in terms of mechanical properties, and from this point of view, some authors argue that composite inlays are superior to ceramic inlays due to their elasticity modulus, which is around 10 MPa, which is much closer to that of dentin (18.6 MPa), and very far from that of ceramics (87.2 MPa).18

Fig 10-12 Correct positioning and working technique of the dentist working in indirect view, using magnification lenses of at least 2.5 x.

Fig 10-13 A digital impression can be used to check the correct parameters of the preparations (depth, parallelism, angles).

Placing the preparation margins is extremely important because subgingival preparations

may generate incorrect impressions, and cementation on radicular cement and dentin, which are areas where adhesion is poor and it is quite difficult to control humidity. Another problem in the subgingival placement of the shoulder is that it does not allow an optical impression of the preparation with intraoral scanners, as all of them so far require a good visibility of the margins. Preparation is performed under magnification, with the use of at least 2.5 × magnifying glasses with strong light, up to the use of a microscope for very accurate preparations. The instruments used for preparation could be the conventional rotary instruments and/or diamond ultrasound inserts (eg, Satelec (EMS), or the wet/dry powder micro-sandblasters, or YAG laser in various forms, eg, Waterlase (Biolase). Isolation is ideally performed with a rubber dam applied over the entire quadrant before starting the preparation. This allows for several simultaneous preparations using fewer anesthetic infiltrations, with all being done in a single session. The preparation begins with a distal tooth, toward the mesial tooth. The preparation shape is dictated by a few factors: the extension of the caries lesion, or the old restoration to be replaced; and the position of occlusal contacts in the enamel, marked before the application of the rubber dam. The shape of the preparation is sometimes modified because of the minimum thickness required by the restorative material: 1.5 mm for pressed ceramics, 2 mm for feldspathic porcelain, less than 1 mm for zirconia, and 1.2 mm for composite (the minimum thickness).12,18 The preparation limit will not be placed on the cusp tip or in the fossa because of the fracture risks. Instead, the preparation will be extended to the cusp slopes or even the buccal and oral surfaces, changing from an inlay to an onlay. The margins are not beveled for ceramic and composite inlays, but they are finished. The depth and the shape of the preparation can be checked with a silicone impression or with an intraoral scanner; the software will point out the retentive areas. After the primary preparation, a careful finishing of all margins and surfaces is necessary and is performed under magnification. All angles resulting from the preparation should be rounded to avoid inducing tensions in the ceramic mass. The final shape of the preparation should allow for the presence of an insertion axis, with slightly divergent walls (4 to 6 degrees), to allow the flow of the adhesive cement and the easy insertion and removal during the try-in, preferably along the tooth axis.8 In the past, various classifications were made, depending on the shape of the preparation, the surfaces involved (the Black classification), the number of surfaces included in the

preparation (3/4, 4/5), and the presence of additional retention grooves. All of these have disappeared with the introduction of the adhesive bonding of tooth-colored indirect restorations, which has practically eliminated most standardized preparation forms. Today, therefore, an indirect restoration could include only one cusp, or just two surfaces of a tooth, or even no tooth preparation in cases of wear and abrasion. These restorations are termed “table-top” by some authors, or “occlusal veneers” by others. The most descriptive term for them was introduced by Pascal Magne, porcelain bonded restorations (PBRs), which comprise all-ceramic restorations prepared in the laboratory that are adhesively bonded to the tooth, whether they replace an incisal angle, a cusp, or three surfaces of a tooth.16,18 10.2.4 Temporary restorations In the presence of gingival inflammation, the impression should be delayed until the remission of the inflammatory process. A provisional inlay should be used, as a lesser-quality material would not restore the contact point and marginal fit, which would favor the healing of the papilla. Otherwise, an impression made before the inflammation has healed will result in an incorrect image of the interdental papilla volume on the special laboratory cast that also reproduces the soft-tissue contour. In this case, the dental technician will manufacture a proximally under-contoured inlay. After the preparation, before the impression, and during the fabrication of the inlay/onlay in the laboratory, the prepared cavity will be protected by the application of a bonding layer. A provisional composite filling will be made, using the resilient Clip (Voco) or Coltosol (Coltène) composite, but care should be taken not to bond the provisional inlay. A thermoplastic material can be easier to use, ie, gutta-percha, which prevents the proliferation of periodontal tissue in the cavity and maintains the contact point.10

Fig 10-14 a Final shape of the cavity resulting after the cleaning of the decay, lining and finishing of cavities on teeth 14 and 16.

Fig 10-14 b Temporary filling using the resilient Clip (Voco) composite at the time of removal.

Fig 10-14 c Etching the cavity with orthophosphoric acid.

Fig 10-14 d The cavity after sealing with primer, before impression.

Fig 10-14 e A precision impression using the conventional method with addition silicone (Flexitime, Kerr).

Fig 10-14 f The virtual model resulting from the scanning of the cast in the laboratory with the Dental Wings software for in-lab CAD/CAM.

An impression can also be made using the digital intraoral scanner technique (CEREC AC Omnicam, Sirona; or E4D Dentist, D4D Technologies), which directly scans the preparation in

the patient’s oral cavity. The dentist will perform the design of the restoration on the virtual model with specialized software (the stages are described in detail in Chapter XII). Or the conventional method could be used, making an impression with precision impression materials such as polyvinyl siloxanes (PVSs) (Take1, Kerr; Aquasil, Dentsply; Imprint 3, (3M ESPE) or polyethers Impregum (M ESPE). A full-arch impression is recommended because a very precise record of the opposing teeth and the occlusion is needed, with the use of the facebow, particularly in the case of complex occlusal reconstructions, with the restoration of the VDO and the group guidance on premolars. In these cases, CAD/CAM milled onlays are preferred, so that functional reconstruction is done in wax or in the virtual articulator. After the impression is made, it is sent to the dental laboratory, where a classic gypsum cast will be made. This will be used for all the laboratory procedures, or it will be scanned for the CAD/CAM inlays. In-lab systems generally use the optical impression of the cast, and the impression is rarely scanned. This is required in the case of a subgingival shoulder, when subgingival scanning is difficult or impossible. In complex cases, the dentist frequently needs to fabricate a provisional restoration (from acrylic or composite) in the dental office, check the occlusion, then rescan the occlusion (double scanning technique). Thereafter, the file is sent to the dental laboratory for optimal functional parameters in the virtual articulator.11 10.2.5 Fabrication of porcelain inlays in the dental laboratory Feldspathic inlays Feldspathic inlays on a refractory die are a technique designed only for highly skilled dental technicians (described in detail in Chapter V). The restoration is extremely fragile, so there is a high risk of fracture before bonding, both in the laboratory and in the dental office. The technique is time-consuming because it uses three different casts: the Willi Geller cast; a cast with removable abutments; and a solid master cast. There are also multiple ceramic firing procedures, without the possibility of subsequent corrections after the try-in.

Fig 10-15 a Composite inlays (Vita LC) on the two single die casts.

Fig 10-15 b Composite inlays during the try-in, without cement.

Fig 10-15 c Composite inlays placed in the cavity with try-in paste (NX3 Nexus, Kerr).

Fig 10-16 a The feldsphathic porcelain inlay on the removable die (Vita VM 7 porcelain).

Fig 10-16 b Feldspathic porcelain inlays during the try-in, without cement.

Fig 10-16 c Feldspathic inlays tried in with the clear try-in paste. Mimicry at the inlay-restoration limit is seen, the best match of all three porcelain systems.

Fig 10-17 a Pressed ceramic inlays (IPS e.max Press, Ivoclar Vivadent) on the removable die cast according to the Willi Geller technique.

Fig 10-17 b Pressed ceramic inlays during the try-in, without cement.

Fig 10-17 c Pressed ceramic inlays in the cavities prepared with try-in paste (Nexus, Kerr) – an almost perfect match between the ceramic restoration and the natural tooth is seen.

Currently, Willi Geller casts can be made from high-precision resin by laser stereolithography, the Strasys company in Israel being one of the leaders in this field.22 It is

very important to mark the prosthetic limit because, compared to other technologies, this is the only one that allows the use of transparent ceramic powder in the transition area, which results in a special chameleon effect.22 In most cases, an additional check is often necessary, particularly in the case of adjacent mesial-occlusodistal and occlusodistal inlays, which allows the dentist to save time during cementation. Occlusion can only be checked after cementation. Premature contact points will be removed with diamond rubber polishers, as there is a risk of diminishing the surface chromatic effects. The insertion in the cavity is performed with the help of special ultrasound rubber tips for a minimal thickness of the cement. Transparent cement is the best choice. Try-in cements can be used, although they are difficult to manage.8,23 Pressed-ceramic inlays/onlays The pressed-ceramic technique has several advantages which have contributed to their widespread use compared to other types of inlays and onlays: it is the fastest of the three techniques; most dental technicians love waxing and the lost-wax technique; inlays can be corrected through additional sintering; and occlusion can be checked before cementation. Pressed ceramic inlays/onlays allow for the functional wax-up, so they are frequently used in cases that require occlusal reshaping, as they generate minimal occlusal interferences. Having a higher flexural strength (up to 300 to 400 MPa), they can also be used for extended table-top onlays in patients who need occlusal augmentation, even in a thickness of up to 3 mm, which is impossible to achieve with conventional layered ceramic. At the other extreme, they can be pressed to 0.3 mm thickness, for minimal shape changes, eg, after orthodontic treatment, in a prepless technique. Cementation is also easier for these types of inlays/onlays because a slight pressure can be exerted without the risk of a fracture. Pressed-ceramic inlays have a higher glass content, so there is a risk of over-etching with hydrofluoric acid, which is why it is recommended that silanization is performed by the dentist in the dental office, not by the dental technician.12

Fig 10-18 a Inlays made using the CAD/CAM technique (ceramics based on lithium dioxide Blue CAD, Ivoclar Vivadent) on the two single removable die casts.

Fig 10-18 b Milled inlays during the try-in – the mismatch of the color/surface appearance of the milled porcelain is seen. An additional stage for optimization in the laboratory with enamel shades or chroma powder is required.

Fig 10-18 c Milled inlays tried in with try-in paste.

Fig 10-18 d CAD/CAM ceramic inlays with ceramic powder for color optimization.

Fig 10-18 e CAD/CAM inlays prepared for glazing.

Fig 10-18 f After optimization firing, the CAD/CAM inlays are sent to the dental office.

Fig 10-18 g An image of the virtual model with the preparations for inlays on the computer screen in our laboratory, where the design of inlays and CAD/CAM milling are performed, using the Dental Wings software, which is compatible with many milling systems (Cercon, 3M Lava).

Fig 10-18 h A detail of inlay restorations proposed by the CAD/CAM software.

Fig 10-18 i Final appearance after the adhesive cementation of composite inlays.

Fig 10-18 j Checking of occlusal contacts at the level of the first maxillary arch quadrant.

Fig 10-18 k Checking the contact points with articulating paper on the opposing teeth.

Weaknesses are related to the monochromatic transition area, which makes them acceptable particularly in posterior areas. Esthetics can be improved by shortening the margins, and a final sintering of either transparent or high-chroma ceramic powders on the cusps and marginal ridges. However, due to the sintering contraction, the marginal gap could increase, as well as the risk of delamination because of the non-homogeneous interface: two materials, one pressed and one sintered. CAD/CAM ceramic inlays/onlays CAD/CAM inlays/onlays are extremely accurate and can be made from two types of ceramic, zirconia and glass ceramic. Zirconia, which is not the most esthetic but is the most resistant, is indicated in patients with high occlusal stress, in extended loss of the contact points, or as mesial retainer for bridges. An easy way to improve the esthetic appearance of zirconia inlays is to design an undersized zirconia shell of 0.4 mm thickness, over which the technician will

subsequently bake layers of feldspathic porcelain powders. A minimum 0.8 mm thickness is required in order to mask the zirconia opacity and restore the transition area with transparent porcelain powders. The second type, glass ceramic inlays, come in the shape of blocks that can also be milled by CAD/CAM (eg, e.max CAD, Ivoclar Vivadent), and combine the advantages of CAD/CAM technology with the esthetics of pressed ceramics.24,25 The try-in of the restorations is performed with Artispot liquid contact marker (Bausch), which is applied on the inside of the inlay. In the case of a too-strong contact, preferably the tooth, not the restoration, is reduced. This is because of the risks of dropping the restoration when it is touched with a rotary instrument, of causing cracks, or of over-shortening its margins. The interdental contact points are also verified with Artispot and, if necessary, are reduced with diamond rubbers. The shape/area of the proximal contact point in inlays/onlays is preferably increased for the protection of the buccal and palatal papillae, and for a higher resistance. The ceramic materials have lower mechanical properties compared to the marginal ridges of the natural tooth, and are subsequently more prone to fracture. The longevity of an indirect esthetic restoration radically depends on the cementation. (Adhesive bonding is detailed in Chapter XI.) Isolation with a rubber dam is essential, and is carried out only after the try-in. The treatment of the prepared tooth surface is identical in both composite and ceramic posterior restorations. An adhesive system, acid-primer-adhesive, is applied, preferably in three steps.19 Composite inlays and onlays will be treated on the internal surface by sandblasting in the laboratory, and the application of a composite activation primer (Composite primer, GC), in order to increase the resin cement–inlay adhesion.23 Porcelain restorations will be treated differently, depending on the type of porcelain used: etchable ceramics (feldspathic and glass ceramic) will be sandblasted in the dental laboratory, etched with 4.5% hydrofluoric acid for 90 seconds, and silanized with a two-component silane (Bis-silane, Bisco). Non-etchable ceramics (zirconium dioxide) will be treated by sandblasting with Rocatec (3M), or the application of a primer (Z-prime, Bisco) that will increase the adhesion. In all esthetic restorations, a dual-curing resin cement must be used. It is applied both to the inner surface of the inlay and to the cavity walls, while the inlay is inserted gradually for a progressive cement overflow, without pressure. The excess cement is prepolymerized for 1 second, in order to be able to remove it during the gel phase, before the final setting, using Gracey curettes. If polymerized for more than 2 seconds, the cement becomes hard and can only be removed with the help of rotary instruments. Final polymerization is performed under

the protection of a glycerin gel (Barrier Gel, Ultradent), which blocks the formation of the oxygen inhibition layer at the cement surface, ensuring chromatic stability in time and preventing marginal infiltration. After cementation and the removal of the rubber dam, occlusion will be checked, as well as the strength of the contact points and the presence of functional or premature occlusal stops. The finishing is performed with diamond rubbers, preferably after 24 hours, because after tooth preparation and impression, a relaxation of periodontal ligaments and a minimal extrusion occur, which sometimes generates a sensation of occlusal overcontour after luting, in the first 24 hours.

Fig 10-19 a Initial clinical situation on tooth 16.

Fig 10-19 b Shape of inlay/onlay preparation before impression.

Fig 10-19 c Cementation under rubber-dam isolation.

Fig 10-19 d Detail after cementation and removal of the rubber dam.

Fig 10-19 a–e Onlay on tooth 16. (Images courtesy of Dr Ionuţ Brânzan.)

Fig 10-19 e, f The inlay after rehydration.

It is recommended to use occlusal guards in all patients with indirect ceramic restorations during the first 4 weeks, and in patients with bruxism, throughout their lives. The patients should also be given special cleaning instructions, eg, water pick, dental flossing, and compulsory follow-up every 6 months for the monitoring of marginal caries.

Fig 10-20 a Initial clinical view.

Fig 10-20 b Inlay preparation before impression.

Fig 10-20 c Single-stage impression (Impregum, 3M ESPE).

Fig 10-20 d A pressed ceramic inlay (Empress 1, Ivoclar Vivadent).

Fig 10-20 e Cementation under rubber-dam isolation.

Fig 10-20 f, g View after cementation and removal of the rubber dam.

Fig 10-20 a-h Inlay on tooth 26. (Images courtesy of Dr Ionuţ Brânzan.) Fig 10-20 h Appearance after rehydration.

10.2.6 Conclusions The need for anterior and posterior esthetic restorations is growing fast. Financial considerations, the long-distance collaboration with the dental laboratory, and the need for additional clinical appointments may lead to a tendency to place composite fillings in posterior teeth as a universal esthetic solution. Although modern composites have improved properties, they are only indicated for small to medium fillings, in areas without excessive occlusal stress. Exceeding these indications will lead to the failure of direct restorations, with all the consequences thereof. It is for these reasons, coupled with their 15 years of experience placing over 4,000 of these composite or porcelain restorations, that the authors recommend the use of indirect esthetic restorations, such as inlays, onlays, and overlays, in the posterior teeth. Of all the ceramic systems, the authors prefer pressed inlays because the laboratory technique is fast and accessible to all technicians. The lithium disilicate inlays have excellent optical properties and the glass ceramic can be acid etched, so the inlay can be bonded to the prepared residual tooth, consolidating the tooth structure. Another great advantage of pressed ceramics (such as IPS e.max Press, Ivoclar Vivadent) is the fact that the same ceramic masses can be used for the fabrication of all types of fixed prosthetic reconstructions, from veneers to short-span bridges, which helps the dental technician’s work in combined cases. Composite and porcelain inlays and onlays are superior to direct restorations because of the following: • Excellent esthetic results. • Restoration of the contact point.

• The ability to reproduce the complex convex-concave morphology of proximal surfaces and occlusal morphology. • Excellent mechanical properties similar to those of the natural tooth (flexural strength, wear resistance). • Abrasion resistance. • Restoration of the VDO. • Finishing/polishing. • Dental tissue economy compared to the preparation necessary for a crown. Relative disadvantages include: • Sensitive technique that is very much dependent on the skills of the dentist. • Additional laboratory cost. • An additional appointment, compared to direct restorations. The last two disadvantages are successfully eliminated by the in-office technology of CAD/CAM porcelain inlays, using systems such as CEREC (Sirona) or E4D Dentist (E4D Technologies). Results are impressive because certain clinical steps are eliminated, including the conventional impression, long-distance transportation to the dental laboratory, and additional clinical appointments. As the inlay can be completed in several hours, the patient no longer needs to be recalled to the office. As the cementation can be performed 3 to 4 hours later, much time is saved for both the dentist and the patient. The precision of these inlays is extremely high, and the materials from which they are milled, zirconia or pressed ceramics, have optimal properties. However, the authors consider that, as things stand today, the ceramist’s work in fabricating these indirect restorations cannot be completely eliminated. After the CAD/CAM milling, for an optimal esthetic result, optimization by a technician through one or two additional firing procedures in a ceramic oven is still required.10,25

REFERENCES 1. Gürel G. The Art and Science of Porcelain Laminate Veneers. Chicago: Quintessence, 2003. 2. Peumans M, De Munck J, Van Landuyt K, Poitevin A, Lambrechts P, Van Meerbeek B. Two-year clinical evaluation of a self-adhesive luting agent for ceramic inlays. J Adhes Dent 2010;12:151–61. 3. Peumans M, Voet M, De Munck J, Van Landuyt K, Van Ende A, Van Meerbeek B. Four-year clinical evaluation of a self-adhesive luting agent for ceramic inlays. Clin Oral Investig 2013;17:739–750. 4. Della Bona A, Kelly JR. The clinical success of all-ceramic restorations. J Am Dent Assoc 2008;139(suppl 4):8S–13S. 5. Christensen GJ. Considering tooth-colored inlays and onlays versus crowns. J Am Dent Assoc 2008;139:617–620. 6. Christensen GJ. Intracoronal and extracoronal tooth restorations 1999. J Am Dent Assoc 1999;130:557–560. 7. Roberson TM, Heymann HO, Swift EJ. Sturdevant’s Art and Science of Operative Dentistry, ed 4. St Louis: Mosby, 2002. 8. Touati B, Nathanson D, Miara P. Esthetic Dentistry and Ceramic Restorations. London: Martin Dunitz, 1998. 9. Goldstein RE. Esthetics in Dentistry, vol 1, ed 2. Hamilton: BC Decker, 1998. 10. Mörmann WH. The evolution of the CEREC system. J Am Dent Assoc 2006;137(suppl):7S–13S. 11. Ivoclar Vivadent. IPS e.max Lithium Disilicate: The Future of All-Ceramic Dentistry. New York: Ivoclar Vivadent 2009. 12. McLaren EA, Whiteman YY. Ceramics: Rationale for material selection. Inside Dent 2012;2:38–52. 13. Land MF, Hopp CD. Survival rates of all-ceramic systems differ by clinical indication and fabrication method. J Evid Based Dent Pract 2010;10:37–38. 14. Lynch CD, McConnell RJ. The cracked tooth syndrome. J Can Dent Assoc 2002;68:470–475. 15. Kramer N, Frankenberger R. Clinical performance of bonded leucite-reinforced glass ceramic inlays and onlays after eight years. Dent Mater 2005;21:262–271. 16. Koubi SA, Margossian P, Weisrok G, et al. Restaurations adhésives en céramique: Une nouvelle référence dans la réhabilitation du sourire. Info Dentaire 2009;91:363–367. 17. Kois JC. The restorative periodontal interface: Biological parameters. Periodontol 2000 1996;11:29–38. 18. Magne P, Belser U. Bonded Porcelain Restorations in the Anterior Dentition: A Biomimetic Approach. Chicago: Quintessence, 2002. 19. Pashley DH, Tay FR, Breschi L, Tjäderhane L, Carvalho RM. State of the art etch-and-rinse adhesives. J Dent Mater 2011;27:1–16. 20. Abbas G, Fleming GJ, Harrington E, Shortall AC, Burke FJ. Cuspal movement and microleakage in premolar teeth restored with a packable composite cured in bulk or in increments. J Dent 2003;31:437–444. 21. Burke FJ, Shortall AC. Successful restorations of load-bearing cavities in posterior teeth with directreplacement resin-based composite. Dent Update 2001;28:388–394, 396, 398. 22. McLaren EA, Chang YY. Creating physiologic contours using a modified Geller cast technique. Inside Dent 2007;3:88–91. 23. Magne P, Stanley K, Schlichting LH. Modeling of ultrathin occlusal veneers. Dent Mater 2012;28:777–782. 24. Rekow ED. Dental CAD/CAM systems: A 20-year success story. J Am Dent Assoc 2006;137:5s–6s.

25. Schlichting LH, Maia HP, Baratieri LN, Magne P. Novel-design ultra-thin CAD/CAM composite resin and ceramic occlusal veneers for the treatment of severe dental erosion. J Prosthet Dent 2011;105:217–226.

10.3 ALL-CERAMIC CROWNS Patients have high esthetic demands not only for anterior but also for posterior teeth, irrespective of the fact that the latter are not fully visible during the movements of the dentomaxillary system, and do not have implications for people’s social life. Yet patients carefully examine the reconstructions they “have paid for”, looking for perfection even in areas that are hardly or not visible at all. If until recently the gold standard in dental practice was porcelain fused to metal (PFM) crowns, more and more patients ask for esthetic solutions up to the last molars. Many no longer accept metal alloys in their mouth, either for esthetic reasons, or because of allergies or the high cost involved (gold-platinum alloys are much more expensive than zirconia nowadays). The question is, what kind of all-ceramic crowns are recommended in the lateral area? As mentioned in the chapter on all-ceramic crowns in the anterior area, there are several classifications. When considering the classification according to the presence of internal substructure, there are two types:1,2 • Crowns with internal substructure. • Crowns without internal substructure (monolithic crowns). 10.3.1 Crowns with internal substructure As in the anterior area, lateral teeth may have crowns with an internal core made of: • Glass ceramic (lithium disilicate). • In-Ceram (Alumina, Zirconia). • Zirconia. Please see Chapter IX, section 9.3 for data on their structure and fabrication technology. In the case of single crowns, all-ceramic restorative systems may be used on any lateral tooth, vital or non-vital, on condition that its crown has enough height to allow the appropriate occlusal reduction, and the final abutment measures at least 4 mm. As far as lateral bridges are concerned: • Zirconia is recommended for any tooth, and the pontic can be more than a single unit, provided that one complies with bridge biodynamics (Ante’s law, periodontal health of the abutment teeth, etc) and minimal connecting area.

• Lithium disilicate, as a bridge substructure, is recommended in the case of three-unit fixed prostheses replacing one missing tooth up to the second premolar; it cannot be used in cantilever bridges. • In-Ceram may be used for bridges replacing one missing tooth, chiefly In-Ceram Zirconia. There is also the possibility of combining a zirconia core with lithium disilicate porcelain. The technique results in improved esthetics due to lithium disilicate porcelain translucency and the faithful duplication of interarch contact points (initially reproduced in wax). Consequently, manufacturing is made easier, chiefly for multiple crowns that can be fabricated in a shorter timespan with much more precision (for instance, IPS e.max ZirPress, Ivoclar Vivadent). Cementation procedures are similar to those discussed in Chapter IX, section 9.3. The preparation of posterior teeth for this type of crown must comply with the following requirements:3 • 1.5 mm axial reduction. • 6 to 8 degrees total occlusal convergence. • 2 mm of the central groove reduction. • Chamfer all round. • About 1 mm thickness of chamfer all round. • Fully rounded angles and margins. • About 2 mm support cusp reduction. 10.3.2 Crowns without internal substructure (monolithic crowns) As their name suggests, monolithic crowns are made of a single material and sized to the final planned volume of the restored tooth. They seem to be the latest trend in restorative procedures involving the lateral area. Conventionally, crowns are made of a metal, porcelain, or zirconia core, covered by layers of porcelain for esthetic appearance and form. The drawbacks of this type of reconstruction are the core-porcelain interface (where cracks appear most often), and the low strength of the porcelain (90 to 110 MPa), irrespective of the strength of the underlying core. Monolithic crowns can be made of lithium disilicate porcelain or zirconia.1,2 10.3.2.1 Monolithic lithium disilicate crowns Monolithic lithium disilicate crowns can be manufactured by using either pressing or

CAD/CAM technology. To customize them after they have been created, they are painted and glazed. Their advantages are a good marginal fit, good esthetics (porcelain ingots are translucent), and high strength (400 MPa in vitro) that can be enhanced by adhesive cementation. 10.3.2.2 Monolithic zirconia crowns Monolithic zirconia crowns are made of pre-sintered zirconia blocks (“green stage”) and manufactured by using CAD/CAM technology from a block, the color of which is similar to the basic color of the tooth. When ready, they are painted, polished, and glazed. Their advantage is a very high strength (about 1,000 MPa). They can therefore be applied to patients with parafunctional activity – bruxism. They are esthetically inferior to lithium disilicate porcelains, but efforts are being made by the manufacturers to produce more esthetic zirconia blocks. Marginal fit is exceptional, and cementation can be conventional. If occlusal changes are made when the reconstruction is tried-in, the zirconia must be repolished, otherwise antagonist tooth wear can result. There are no long-term studies that could enable us to estimate the wear degree of natural antagonist teeth inflicted by monolithic zirconia. It seems that well-polished zirconia (mirror-like) is quite friendly to the antagonists.4 The major advantage of monolithic crowns is that they require less-invasive tooth preparation (space is needed for one material only). They can therefore be applied even when there is not enough occlusal space. The preparation should meet the following requirements:3 • 1.5 mm axial reduction. • 6 to 8 degrees total occlusal convergence • The reduction of the central groove ranges between 0.5 mm, 1 mm, and 1.5 mm; under the circumstances in which the occlusal space is less than 1 mm, the crown has enough strength, but the final shape of the occlusal area will not look very natural.

Fig 10-21 Initial clinical status of 36.

Fig 10-22 36 detail of tooth preparation for a layered lithium disilicate crown.

Fig 10-23 36 detail – occlusal view.

• Chamfer all around. • 0.3 to 0.5 mm thickness of chamfer all around; in case of zirconia, manufacturers allow knife-edge preparation, but there is the risk of chipping. • Fully rounded angles and margins. • 1 to 1.2 mm support cusp reduction. 10.3.3 Survival studies The 10-year survival rate of lithium disilicate porcelain is similar to the PFM survival rate; consequently, it can be regarded as a good alternative, irrespective of the cementation technique. At the same time, studies dedicated to zirconia endurance seem to advocate its use, but with the caution that the timespan of use is not as long as in the case of PFM or other all-ceramic restorations (Figs 10-21 to 10-25).5–12

Fig 10-24 36 detail – lateral view.

Fig 10-25 Lithium disilicate crown translucency.

REFERENCES 1. Giordano R, McLaren E. Ceramics overview: Classification by microstructure and processing methods. Compend Contin Educ Dent 2010;31:682–684. 2. Fradeani M, Barducci G. Esthetic Rehabilitation in Fixed Prosthodontics: Prosthetic Treatment, vol 2. Chicago: Quintessence, 2008. 3. Massironi D, Pascetta R, Romeo G. Precision in Dental Esthetics. Chicago: Quintessence, 2007. 4. Winter B. Posterior Full-Contour Zirconia Crowns: Preparation Design. Scottsdale: Spear Education, 2012. 5. Cortellini D, Canale A. Bonding lithium disilicate ceramic to feather-edge tooth preparations: A minimally invasive treatment concept. J Adhes Dent 2012;14:7–10. 6. Kern T, Tinschert J, Schley JS, Wolfart S. Five-year clinical evaluation of all-ceramic posterior FDPs made of In-Ceram Zirconia. Int J Prosthodont 2012;25:622–624. 7. Raigrodski AJ, Hilstead MB, Meng GK, Chung KH. Survival and complications of zirconia-based fixed dental prostheses: A systematic review. J Prosthet Dent 2012;107:170–177. 8. Roumanas ED. The clinical reliability of zirconia-based fixed dental prostheses appears acceptable but further research is necessary. J Evid Based Dent Pract 2013;13:14–15. 9. Stawarczyk B, Özcan M, Schmutz F, Trottmann A, Roos M, Hämmerle CH. Two-body wear of monolithic, veneered and glazed zirconia and their corresponding enamel antagonists. Acta Odontol Scand 2013;7:102–112. 10. Janyavula S, Lawson N, Cakir D, Beck P, Ramp LC, Burgess JO. The wear of polished and glazed zirconia against enamel. J Prosthet Dent 2013;109:22–29. 11. Preis V, Weiser F, Handel G, Rosentritt M. Wear performance of monolithic dental ceramics with different surface treatments. Quintessence Int 2013;44:393–405. 12. Kern M, Sasse M, Wolfart S. Ten-year outcome of three-unit fixed dental prostheses made from monolithic lithium disilicate ceramic. J Am Dent Assoc 2012;143:234–240.

FLORIN LĂZĂRESCU ALECSANDRU IONESCU

Chapter XI LUTING PROTOCOL FOR ALL-CERAMIC RESTORATIONS

11.1 CHOICE OF THE RESIN CEMENT Bonding represents a special adhesive connection between the dental and ceramic pre-conditioned surfaces through the physical and chemical properties of the interposed resin. Clinical studies show that adhesive cementation (eg, resin cements) yields better results than other types of cementation (eg, zinc phosphate cements, glass ionomer cements).1,2 As dental materials have been detailed in Chapter V and adhesion is comprehensively explained in Chapter VII, this chapter will describe the luting clinical protocol. Temporary luting is strongly contraindicated in the case of single restorations. Due to the intimate marginal adaptation, removal of the prosthesis can damage the restoration’s structural integrity.3 At the same time, temporary luting may affect long-term adhesion. Comparative studies were performed between all-ceramic restorations that were definitively luted, and restorations that were temporarily luted with eugenol-based and eugenol-free cements. The results indicate a superior adhesion of all-ceramic restorations that were definitively luted, with insignificant differences between temporary luted restorations with eugenol-based and eugenol-free cements.4 The use of resin cements (Fig 11-1)17 is mandatory in the case of silicate-based ceramics (feldspathic and glass-ceramic restorations), because they can be etched. Furthermore, this is just one option for infiltration technique ceramics (eg, alumina- and zirconia-based ceramics, such as Vita In-Ceram Alumina or Vita In-Ceram Zirconia) or crystalline oxide ceramics (zirconium dioxide and aluminum oxide), as there are other materials and techniques that can be considered.5 Even in these cases, comparing the use of traditional techniques and cements like zincphosphate or glass ionomer cement with the use of adhesive techniques and resin cements, it was concluded that resin cements provide better cementation due to the higher strength of materials (laboratory studies) and a better seal of the resin-ceramic interface.17 The debate in the case of resin cement is whether to use dual-cure (auto-cured and lightcured) cements, or only light-cured cements. The use of the former is debatable due to the chromatic instability that may occur as a result of the degradation of the amino compounds6 in

their structure. It has been clinically demonstrated that light-cured cements are not inferior compared to dual-cured cements, if the light-curing time is respected (between 60 and 120 seconds for each surface of the restoration, depending on the intensity of the curing light).

Fig 11-1 a Resin cement kit.

Fig 11-1 b Initial clinical situation of 12.

Fig 11-1 c Final clinical situation – luting of 22.

In most cases, dual-cured cements can be avoided due to their handling difficulties (shorter working time) and chemical instability. They are indicated for ceramic restorations that are either thicker than 2 mm, or very opaque (eg, when covering tooth discoloration).5

11.2 EXAMINATION OF ALL-CERAMIC RESTORATIONS After the removal of the provisional crowns, the cement residues should be cleaned out from the dental surfaces with the usual instruments, and subsequently, with a slightly abrasive paste. Prior to the conditioning of dental and ceramic surfaces, a final examination of the restorations is made in situ with a try-in glycerin-based paste, which is the exact color of the resin cement to be used (Figs 11-2, 11-3a and 11-3b). As more and more ceramic restorations are thin and transparent, the resin color can change the final appearance of the restoration. Patients are not allowed to bite because of the high risk of the non-bonded restoration fracturing. After the try-in, dental surfaces to be bonded are perfectly isolated using retraction cords and a rubber dam.7 Some specialists recommend the use of 3.0 silk suture instead of conventional retraction cords. Depending on the type of preparation performed, the type of restoration, and the clinician’s choice, the rubber dam can be applied in several ways. The conventional technique involves the alternate application of the clamp on each tooth or group of teeth on which the ceramic restorations will be bonded. This is the preferred technique, especially when the preparation limit is placed slightly subgingivally. The great disadvantage of this technique is the lack of perspective and visibility of the symmetry points during cementation in the anterior area, as well as the gingival irritation that can be caused by the clamps. The alternative technique meant to eliminate these disadvantages, particularly for non-prep veneers and juxta/supragingival preparations, is to cut out the rubber dam over the entire working area and place the clamps distally. The rubber dam’s free margins can be either glued to the fixed gingiva with cyanoacrylate, or rolled buccally on a cotton-roll placed in the vestibule (Figs 11-4a and 114b).

Fig 11-2 Application of the try-in paste.

Fig 11-3 a, b Clinical examination of different try-in pastes.

Fig 11-4 a, b Isolation with rubber dam.

Fig 11-5 Protection of the adjacent teeth with Teflon tapes.

Before conditioning the surfaces, one last examination of the restoration’s insertion and marginal closure is made with the rubber dam placed in situ. Teflon tapes should be used on adjacent teeth while bonding in order to prevent their accidental conditioning, particularly when the contact points are preserved, otherwise the excess resin may adhere to the adjacent dental surfaces, which is extremely difficult to remove (Fig 11-5). Before luting, special attention is required to avoid the contamination of the ceramic surfaces with polishing paste, latex from the gloves, saliva, or materials used for try-in (silicone material, try-in paste), which will decrease adhesion strength.23 The internal ceramic surfaces of the restorations to be luted should be carefully cleaned with solvents such as acetone, ethanol, methanol, and methyl chloride.12

11.3 CONDITIONING OF THE DENTAL AND CERAMIC SURFACES 11.3.1 Conditioning the ceramic restorations Hydrofluoric acid conditioning is compulsory for glass-ceramic restorations (silica-based dioxide) (Figs 11-6 and 11-7). There are divergent opinions regarding the application time of hydrofluoric acid (from 60 seconds, to 2 to 3 minutes), as well as its concentration (from 2.5% to 10%).7,13,14,15 Relevant studies have concluded that the number, the size, and the distribution of the leucite crystals influence the formation of microporosities created by hydrofluoric acid. This is why the application time and concentration may vary depending on the type of ceramic from which the final restoration is made. For feldspathic porcelain reinforced with leucite crystals, the application of a 9% HF solution for 60 seconds has proved to be the most satisfactory formula. Sandblasting is recommended for this type of ceramic, followed by hydrofluoric acid etching and silanization of the ceramic surfaces.14 The studies performed over a 20-year period on 318 porcelain veneers made from both feldspathic ceramic and lithium disilicate ceramic in 84 patients – of whom 50% had bruxism – using various adhesive systems (96% of the cements used being light-cured cements) led to the following conclusions: the success rate was 94.4% at 5 years, 93.5% at 10 years, and 82.93% at 20 years. Only 7% of failures were attributed to decementation, the risk of failure being 7.7 times higher in the case of patients with bruxism.7 However, analyzing the adhesion of porcelain restorations with a zirconia infrastructure yields different results. Currently, the most frequently recommended zirconia-conditioning method is to combine the sandblasting of the surfaces to be cemented using silica-covered alumina particles (50 to 110 µm) and chemical conditioning with a phosphate-based monomer, such as 10-methacryloyloxydecyl dihydrogen phosphate (MDP). The recommended cement should preferably include MDP, which allows for better adhesion.8 However, studies showed that after 150 days, the restorations that had been cemented and conditioned using this method had a high failure rate.9

Fig 11-6 Hydrofluoric acid etching the restoration.

Fig 11-7 Appearance of the restoration after hydrofluoric acid conditioning.

It should be noted that eliminating the sandblasting while using chemical conditioning with MDP alone significantly decreases adhesion, which leads to the conclusion that sandblasting is very important in obtaining good adhesion.10 New cementation techniques are tested in order to obtain superior adhesion. A method that has shown very good clinical results involves covering the internal surfaces of an all-ceramic restoration with different disilicate-based ceramics, which can be easily conditioned with hydrofluoric acid. In a comparative in vitro study performed on sintered zirconia discs, three treatment approaches were used: the control group had an untreated surface; the second group underwent sandblasting with alumina particles of 50 µm, at a pressure of 0.2 MPa, from a distance of 10 mm, for 15 seconds; and the third group was treated using a selective infiltration etching (SIE) technique, the zirconia surfaces being covered with a solution composed of silicon (65%), alumina (15%), sodium oxide (10%), potassium oxide (5%), and titanium oxide (5%). The zirconia samples were heated at 750°C, in an air environment, for 3 minutes. The

results were analyzed both before treatment in a wet environment and using artificial aging techniques, in a wet environment, after 4, 26, 52, and 104 weeks. The conclusions of the study were clearly in favor of SIE, followed by the sandblasted group, and finally by the control group.11 This type of restoration can also be cemented with traditional cements, except for zinc phosphate cements, the opacity of which would cancel the esthetic advantages of a metal-free restoration.3 Equally important is the cleaning of the glass matrix obtained following etching. Comparative studies regarding the best method for cleaning the treated surfaces have been carried out. After 10% hydrofluoric acid conditioning for 20 seconds, and water spraying for 60 seconds, the following cleaning methods were used: water spraying for 4 minutes, followed by drying; cleaning in an ultrasound bath with distilled water for 4 minutes, followed by drying; cleaning in an ultrasound bath with a 99.5% acetone solution for 4 minutes, followed by drying; cleaning in an ultrasound bath in a 70% alcohol solution for 4 minutes, followed by drying. The results demonstrated that the optimal cleaning solution was the ultrasound bath with distilled water (Fig 11-8).16 11.3.2 Silanization In the case of silicate dioxide-based ceramics, a chemical bond to the resin cement is created. This is due to the bond between the methacrylate group inside the 3methacryloxypropyltrimethoxysilane molecule, the most widely used silane in dentistry, and the methacrylate group inside resin cement and adhesives.

Fig 11-8 Cleaning of the restoration in the ultrasound bath with distilled water.

In order for the silane to function as a ceramic bonding agent, it should be hydrolyzed, usually by means of acetic acid. Silane may come in a prehydrolyzed form directly from the manufacturer, or in a nonhydrolyzed form, in a two-component system. In the case of the former, solutions have a limited period of shelf life: it is advised to keep them in the refrigerator and to bring them to room temperature before use, as well as to use them within a year. Also, if the solution has lost its clarity, replacement is recommended.

Fig 11-9 Silanization.

Fig 11-10 The restoration after silanization.

In the case of the two-component system (non-hydrolyzed silane solution, and ethanol and acetic acid and water), the mixture is made by the practitioner before application. There are contradictory opinions regarding the duration of hydrolysis, which varies from 5 minutes to 2 hours. The life duration of solutions is longer, the two-component system being indicated particularly when silane is not frequently used by the dentist.18

It is recommended that no more than two to three silane layers be applied, with a pause between applications to allow the evaporation of the solvent (Fig 11-9).7 It has been generally accepted that thermal treatment improves the effect of silane, but opinions are also divided. In one particular study, a single-component silane and a twocomponent silane were applied on a ceramic surface. The surfaces were then heated at 20°C, 40°C, 60°C, 80°C, and 100°C for 5 minutes. Subsequently, an adhesive substance and a lightcured resin cement were applied on the ceramic surface. The results of this test showed that in the case of both silane systems, heating at 60°C during silanization generated better adhesion, which increased between 20°C and 60°C and decreased between 60°C and 100°C. In conclusion, the heating temperature should be lower than the silane boiling temperature.19 The surface appearance after the application of silane should be chalky, the same as before its application (Fig 11-10). If a glossy surface is noted, possibly due to the application of a too-thick silane layer, it is advised to resume the procedure (sandblasting, hydrofluoric acid etching, silanization). Silanization is not useful in the case of ceramic restorations obtained using the infiltration technique (eg, In-Ceram Alumina, In-Ceram Zirconia), and polycrystalline oxide ceramics (alumina, zirconia). The next step consists of applying the bonding over the ceramic surface in a thin film, followed by the application of the adhesive resin cement (Fig 11-11). Light curing the bonding prior to the application of resin is not indicated because it can affect the precise marginal adaptation at the preparation. 11.3.2 Conditioning of the dental surface It is very important that preparations remain strictly in enamel, due to very good adhesion and the absence of postoperative sensitivity. In the case of 80% to 90% preserved enamel at the preparation level, 37% phosphoric acid for 30 seconds should be applied using the total etching technique, followed by washing and drying. The adhesive system is subsequently applied.7 (See details referring to adhesive systems in Chapter VII.) In the case of preparations with a large amount of exposed dentin, a dentinal adhesive system should be applied right after the preparation, before applying the provisional prosthetic restorations, in order to eliminate postoperative sensitivity during the temporary restorations, and also to prevent the contamination of dentinal tubules with different extrinsic factors.7 The etching technique in this case is the selective one, with the previous application of the acid at

the enamel margins for 15 seconds, followed by dentin acid etching for another 15 seconds. However, new generations of adhesives contain a self-etching system that no longer requires separate etching and simplifies the procedure. One other consideration relates to how the adhesion strength is influenced by the patient’s age and the duration of the acid application. In a study performed on 100 extracted teeth with an exposed dentinal surface, grouped by age (15 to 25 years, 35 to 55 years, and over 55 years), using all the etching types previously described, the light-curing durations indicated by the producer were compared to longer durations.

Fig 11-11 The restoration after the bonding application.

The conclusions of the study showed no significant differences in the reduction/increase of

adhesion strength depending on age or light-curing duration.21 The use of fourth-, fifth-, sixth- and seventh-generation adhesives, correlated with the strict observance of the manufacturer’s instructions, can ensure the success of luting.

11.4 LUTING RESTORATIONS

THE

CERAMIC

Fig 11-12 Light curing.

Protective measures should be taken against the working-station light, especially against the LED light (including the LED light of the dental loupes), which may accelerate cement setting and cause undesired complications. The restoration is placed considering the insertion axis, with continuous moderate pressure in order to allow excess cement to overflow the margins of the preparation. In this way, the clinician can control the marginal adaptation of the ceramic restoration,24 which requires maximum attention in the case of non-prep restorations. To facilitate the positioning of non-prep restorations, the use of a low-viscosity cement is preferred. After positioning the restorations, any movement should be avoided. In the case of multiple preparations (eg, canine to canine), the luting order is central incisor, then the lateral incisor, and finally the canine. This is done mainly for esthetic reasons, due to the possibility of a visible effect when loosening the contact points, which might have been unnoticed in the try-in phase. This effect decreases as the teeth have a more distal position on the dental arch. Next, the Teflon tapes and the bulky resin excess are removed from the adjacent teeth. The fine resin excess is removed using a cotton applicator. Light curing is performed on all surfaces, intermittently, in order to prevent the heating of soft tissues and the pulp of vital teeth (Fig 11-12). The use of a glycerin layer on the margin of the preparation is advised during light curing. It has been proved that light-cured margins that are not covered by the glycerin layer encounter more rapid staining due to oxygen inhibition during polymerization.7,20

The complete removal of resin excess from the gingival sulcus is extremely important because even the smallest residue can lead to gingival inflammation. This is done with a fine scalpel, under rubber-dam isolation. It is not recommended to use rotary instruments as they are likely to create rough surfaces that will generate gingival irritation.7 In the case of non-prep veneers or juxta- and supragingival restorations, the removal of cement excess is easily performed after a 1 to 2 second precure. However, this procedure should be executed very carefully because of the high risk of mobilizing the partially cured restorations, especially in the case of non-prep veneers. When removing the resin excess in subgingival restorations, particular attention should also be taken due to the lack of direct visual control at the toothcrown interface. Gingival inflammation can also be caused by the subgingival placement of the shoulder, by the presence of rough surfaces at the tooth-crown interface, or by the presence of a shoulder between the tooth and the crown surface. A radiograph control is advised postcementation, and the patient should be recalled for follow-up shortly after cementation for a re-examination and the removal of all cement residues.3 During this appointment, in addition to the functional examination and the removal of potential resin residues, the dentist should also check the patient’s ability to maintain good oral hygiene.3

Fig 11-13 Photo of the preoperative situation.

Fig 11-14 Photo of the preparation.

Fig 11-15 a, b Photos of the postoperative situation.

In the same appointment, final postoperative photographs should be taken, which will be added to the photographic documentation of the preoperative and intraoperative situations (Figs 11-13 to 11-15).

11.5 EXAMINATION OF OCCLUSAL RELATIONS: SPECIAL CONSIDERATIONS The static and dynamic occlusal control of all-ceramic restorations should be performed after luting because of the high risk of fracture prior to cementation. Functional checkups in centric relation and anterior and lateral guidance are proceeded with, and adjustments are made when premature contacts and interferences are present (Figs 11-16a to 11-17c). Ceramic polishers are used afterwards. For long-term success of the ceramic rehabilitations, the treatment plan should always respect the functional considerations, even if sometimes it requires interdisciplinary treatments. Accurate design reproduction of the already tested provisional restorations in definitive restorations will facilitate the functional, mechanical integration after luting.3 A particular situation that can be encountered is bleeding before or during the luting procedures. In a study made on 100 extracted teeth, the following possible clinical situations were simulated: the interposition of coagulated blood between the tooth and the restoration; the interposition of fresh blood between the tooth and the restoration; and the blood removal with various solutions (3% hydrogen peroxide, 0.4% to 0.5% sodium hypochlorite-based antiseptic solution, 4% boric acid). Solutions were applied on the tooth surface for 10 seconds, or the tooth surfaces were wiped by friction for 10 seconds, followed by rinsing for 10 seconds. The results showed that blood interposition in any state affects the adhesion. They also showed that the use of friction in the cleaning process does not influence the results, and rinsing with a water jet for 10 seconds is sufficient to remove blood contamination from dental surfaces.22 These in vitro results can be clinically used in the case of minor bleeding only. Otherwise, the luting is highly contraindicated, the recommendation being to postpone the procedure or repeat all stages.

Fig 11-16 a Initial situation.

Fig 11-16 b Final situation.

Fig 11-17 a–c Functional checkup.

REFERENCES 1. Alvaro D, Kelly JR. The clinical success of all-ceramic restorations. J Am Dent Assoc 2008;139(suppl 4):8S– 13S. 2. Kelly JR. Dental ceramics: Current thinking and trends. Dent Clin North Am 2004;48:513–530. 3. Fradeani M, Barducci G. Esthetic Rehabilitation in Fixed Prosthodontics, vol 2. Chicago: Quintessence, 2008. 4. Bagis B, Bagis H. Bonding effectiveness of a self-adhesive resin-based luting cement to dentin after provisional cement contamination. J Adhes Dent 2011;13:543–550. 5. Darr AH, Jacobsen PH. Conversion of dual cure luting cement. J Oral Rehabil 1995;22:43–47. 6. Beier U, Dumfahrt H. Clinical performance of porcelain laminate veneers for up to 20 years. Int J Prosthodont 2012;25:79–85. 7. Magne P, Belser U. Bonded Porcelain Restoration in the Anterior Dentition. Chicago: Quintessence, 2003. 8. Petre A, Sfeatcu R. Adhesive cementation protocol of zirconia restorations. Rom J Oral Rehabil 2011;3:114– 119. 9. Wolfart M, Lehmann F, Wolrfanrt S, Kerrn M. Durability of the resin bond strength to zirconia after using different surface conditioning methods. Dent Mater 2007;23:45–50. 10. Aboushelib MN, Klervalaan CJ, Feilzer AJ. Selective infiltration-etching technique for a strong and durable bond of resin cements to zirconia-based materials. J Prosthet Dent 2007;98:379–388. 11. Moustafa N. Evaluation of zirconia/resin bond strength and interface quality using a new technique. J Adhes Dent 2011;13:255–260. 12. Barghi N, Chung K, Farshchian F, Berry T. Effects of the solvents on bond strength of resin bonded porcelain. J Oral Rehabil 1999;26:853–857. 13. Chen JH, Matsumura H, Atsuta M. Effect of different etching periods on the bond strength of a composite resin to a machinable porcelain. J Dent 1998;26:53–58. 14. Blatz M, Sadan A, Kern M. Resin-ceramic bonding: A review of the literature. J Prosthet Dent 2003;89:268– 274. 15. Barghi N, Fischer D, Vatani L. Effect of leucite content of porcelain, types of etchant and the etching time on porcelain-composite bond. J Esthet Restor Dent 2006;18:47–52. 16. Martins M, Leite F, Queiroz J, Vanderlei A, Feres H, Ozcan M. Does the ultrasonic cleaning medium affect the adhesion of resin cement to feldspathic ceramic? J Adhes Dent 2012;14:507–509. 17. Burke T, Flemming G, Nathanson D, Marquis P. Adhesive Technology for Restorative Dentistry. Chicago: Quintessence, 2005. 18. Gary A. Preparing Porcelain Surfaces for Optimal Bonding. Funct Esthet Restor Dent 2008;2:38–49. 19. Wang Y, Chen J, Xiao Y. The Effect of Heating on Silanization in Ceramic Bonding. 8th Annual Scientific Meeting of IADR Chinese Division, 2007; Poster session. 20. Bergmann P, Naack MJ, Roulet JF. Marginal adaptation with glass-ceramic inlays adhesively luted with glycerine gel. Quintessence Int 1991;22:739–744. 21. Oliveira GC, Oliveira GM, Ritter A, Heymann H, Swift E, Yamauchi M. Influence of tooth age and etching time on the microtensile bond strengths of adhesive systems to dentin. J Adhes Dent 2012;14:229–234. 22. Tachibana A, Castanho G, Vieira S, Matos A. Influence of blood contamination on bond strength of a

etching adhesive to dental tissues. J Adhes Dent 2011;13:349–358. 23. Gürel G. The Science and Art of Porcelain Laminate Veneers. Chicago: Quintessence, 2003. 24. Massironi D, Pascetta R, Romeo. Precision in Dental Esthetics: Clinical and Laboratory Procedures. Chicago: Quintessence, 2007.

FLORIN LĂZĂRESCU

Chapter XII IN-OFFICE DENTAL CAD/CAM TECHNOLOGY

12.1 SYSTEM DESCRIPTION CAD/CAM technology has become an important field of dentistry and prosthodontics in the last decade, both for laboratory technicians and dentists, as well as for the dental industry. It is the technology of the future that will increase dental therapeutic efficiency, standardize prosthetic restorations, and develop new materials for and concepts of dental treatment. The many benefits associated with CAD/CAM technologies include a high quality of industrially prefabricated blocks, the standardized quality of restorations, reproducibility made possible by digital technology, spectacular reduction of manufacturing costs, and, not least, access to innovative materials. The term CAD/CAM is currently being used as a synonym for prosthetic restorations produced by milling technology. A closer look reveals that the acronyms do not provide any information on the method of fabrication: CAD stands for computer-aided design, while CAM is the abbreviation of computer-aided manufacturing. All CAD/CAM systems consist of three components: • A scanner that converts the collected images into digital data that can be processed by a computer (Fig 12-1). • Specialized software that processes data and designs restorations. • A production technology that transforms the data set into a finished product (Fig 12-2).

Fig 12-1 CAD/CAM CEREC Bluecam scanner (Sirona).

Fig 12-2 CAD/CAM CEREC MC XL dental milling device (Sirona).

Fig 12-3 a, b CAD/CAM Ceramill – Amann Girrbach. (Images courtesy of Amman Girrbach.)

Fig 12-4 a, b CAD/CAM Ceramill – Amann Girrbach. (Images courtesy of Amman Girrbach.)

Depending on the location of the components, CAD/CAM systems can be classified as follows: • Chairside CAD/CAM systems. • Laboratory CAD/CAM systems. • Milling centers. 12.1.1 Chairside CAD/CAM systems Chairside CAD/CAM systems include a scanner and a milling device (Figs 12-1 and 12-2). The conventional impression is replaced by a digital optical impression, and in most cases the prosthetic restoration is manufactured on the spot, which is a major time-saving advantage. 12.1.2 Laboratory systems Laboratory systems involve taking a traditional impression and sending it to the laboratory, where the technician fabricates the casts. The casts are scanned and the restorations are manufactured by using the CAD/CAM technique (Figs 12-3a to 12-4b). Of course, it is possible to send an optical impression to the laboratory if it can be taken in the office. Thus, the technician only fabricates the restoration infrastructure and the ceramist finishes it in the traditional manner; or, depending on the material, the final restoration can be milled from the very beginning. 12.1.3 Milling centers Dental laboratories equipped merely with the optical impression unit send the data set online

to a milling center. There is a substantial financial benefit, chiefly for the laboratory, since the purchase of a milling machine is no longer required. The final or core restoration is then sent back to the laboratory. However, it is difficult for the dental practitioner to resort to a milling center, since in most cases the dental laboratory must also be involved (for example, in the manufacturing of bridges), which makes the whole circuit too complicated and ineffective. Essentially, only inlays, onlays, crowns, veneers, and small bridges can be manufactured without the need of the laboratory. The most important aspect to be taken into consideration in all the above-mentioned cases is that the intraoral data collection system should be open, so that the data set may be read and processed by the various digitization and processing devices available in the dental laboratory. This chapter deals specifically with chairside CAD/CAM systems (intraoral scanners, milling machines, and materials for processing using in-office CAD/CAM devices). 12.1.4 Scanners There are two types of scanners: • Optical scanners. • Mechanical scanners. The principle of optical scanners is the collection of data based on triangulation; namely, the source of light and the receptor unit are in a definite angle in their relationship to one another. The angle enables the computer to calculate a three-dimensional (3D) data set from the image on the receptor unit. Mechanical scanners are based on “line-by-line reading” of the scanned 3D structure. The image is very accurate, but the data set is not easy to process, which makes these devices more difficult to use than optical scanners.1 Intraoral scanning is gaining ground as CAD/CAM technology finds applications in an increasing number of fields: restorative therapy, prosthodontics, implantology, and orthodontics. Stone models have been and still are the foundation of prosthetic restorations.2 The traditional workflow (impression-taking, casting, restoration) has proven its effectiveness, even taking into consideration the flaws caused by the fact that impression materials are prone to contraction,3 and stone will show expansion due to secondary reactions while setting.4 The aforementioned changes may result in a misfit of the final prosthetic restorations, bringing

about forces on the underlying teeth. Natural teeth can move 25 to 100 µm in an axial direction, and 56 to 108 µm in a horizontal direction,5,6 the periodontal ligaments allowing for tiny readjustment in the case of a slight misfit of the prosthetic work. Implants, on the other hand, only show a range of motion of 3 to 5 µm in an axial direction, and 10 to 50 µm in a horizontal direction.6 Changing traditional procedures by replacing tooth impression with intraoral scanning may already eliminate the aforementioned errors in the early stages. Besides these benefits, the short manufacturing time of prosthetic restorations (when scanners are accompanied by milling devices) has resulted in CAD/CAM technology gaining more ground. At present, there are 11 intraoral scanners available on the market: four made in the USA; two in Germany; two in Israel; and the other three in Italy, Switzerland, and Denmark, respectively.7 All these systems (listed below) have the advantage of producing high-fidelity models and creating 3D archives: • CEREC – Sirona Dental System (DE). • iTero – Cadent (IL). • E4D – E4D Technologies (US). • Lava COS – 3M ESPE (US). • IOS FastScan – IOS Technologies (US). • DENSYS 3D – Densys (IL). • DPI-3D – Dimensional Photonics International (US). • 3D Progress – MHT (IT) and MHT Optic Research (CH). • DirectScan – Hint-Els (DE). • Trios – 3Shape (DK). Although the scanners use different systems for capturing images (for instance, CEREC AC employs light-stripe projection and active triangulation to generate 3D images,8 Cadent iTero employs a parallel confocal imaging technique for capturing 3D images,9 while Lava COS uses active wavefront sampling to obtain a 3D model of the dentition10), all available systems aim at minimizing image blurring, since the optical properties of the scanned surfaces may affect the accuracy of the scan data.

Fig 12-5 MC XL – Sirona milling and grinding unit. (Image courtesy of Sirona.)

Fig 12-6 a, b E4D system. (Image courtesy of E4D Technologies.)

Certain scanners require that the teeth be dusted with anti-reflective titanium oxide powder (eg, CEREC – with Bluecam, Lava COS), whereas others do not (eg, CEREC – with Omnicam, iTero, Trios, E4D). 12.1.5 Design software Design software is provided by manufacturers for the design of various dental restorations (inlays, onlays, crowns, bridges, veneers, surgical guides, implant superstructures, telescopic primary crowns). The software is constantly improving, the different generations of CAD/CAM systems being set apart mostly by their construction software, and much less by the changes in impression-taking or processing devices. The data are chiefly stored in STL (standard transformation language), but, as mentioned above, manufacturers may use their own data formats, with the result that data from different construction programs are not compatible with each other.1 12.1.6 Milling machines Milling machines are distinguished by means of the number of milling axes (three to five). The only chairside systems used in-office are CEREC MC XL (Sirona) and E4D (E4D Technologies) (Figs 12-5 to 12-6b), the others being intended for dental technical laboratories. There are dry or wet milling procedures. Chairside milling employs a mixture of distilled water and lubricating oil.

12.2 CLINICAL INDICATIONS/TYPES OF RESTORATIONS As mentioned in the previous section, there are only two systems that include chairside milling machines (CEREC MC XL, Sirona; and E4D, E4D Technologies). Until recently, the major differences between them were related to the fact that the CEREC system required previous dusting of the scanned surface with titanium oxide powder (a problem solved by the Omnicam scanner). Also, data transmission from scanner to milling machine was different: CEREC systems had a constant flow, while it was necessary to press the command button with E4D systems. The following sections mainly focus on the CEREC system, because it is the earliest (over 25 years old) and most widely used, which means that research studies have already been conducted on various types of preparations. Whereas early models of CAD/CAM systems were chiefly used for inlays, onlays, overlays, and veneers, they soon diversified, allowing the fabrication of crowns and bridges, surgical guides, and implant abutments (for implant abutments, the scan must be sent to the dental laboratory). Due to the relatively limited use of CAD/CAM systems compared to traditional technology, this section calls attention to the research that substantiates the success of this procedure, as well as the materials used, rather than to cavity or tooth preparation techniques, which are similar for all ceramic restorations, and which are extensively described in Chapters IX and X. 12.2.1 Inlays/onlays/overlays Making these types of restorations using CAD/CAM technology is the choice solution in many clinical situations. Many studies have been conducted in order to test the performance of these types of restorations. In one of them, 2,328 inlays/onlays were placed in 794 patients between 1990 and 1997 (using CEREC 1), and between 1997 and 1999 (using CEREC 2). Microscopic examination of 44 randomly selected restorations revealed an average marginal fit of 236 μm ± 96.8 μm.11 The success rate was 95.5%, and only 35 restorations were lost, mainly because of tooth extraction. No connection between failure and restoration size or location was found (Figs 12-7 and 12-8). A 15-year comparative study between CEREC inlays, inlays made in the technical laboratory, and gold inlays was conducted at the University of Graz, Austria. Ninety-three gold

inlays were cemented using zinc phosphate, 71 gold inlays were bonded, 94 inlays were made in the laboratory (Dicor, Optec, Duceram, Hi-ceram), and 51 inlays were made using CEREC (ceramic Vita Mark I). Forty-nine devitalized teeth were treated: 5 with the gold restorations cemented with zinc phosphate, 14 with bonded gold inlays, 22 with inlays made in the laboratory, and 8 using CEREC.12

Fig 12-7 Restoration design.

Fig 12-8 Inlay restoration.

Fig 12-9 Crown restoration.

Fig 12-10 Postoperative clinical status.

The following parameters were analyzed; loss or total fracture, partial fracture of the restoration or tooth, decementation, secondary cavity development, and vitality loss. In all study groups, inlays placed on devitalized teeth were found to perform more poorly than those placed on vital teeth. There was not a statistically significant difference between gold and CEREC inlays (~ 93% success rate over 15 years). The performance of laboratory-made inlays was noticeably poorer (68%). Other studies evaluated the time performance of various types of materials used in lateral teeth restorations. The statistics of annual loss rate provided the following results: glass ionomer (7.7%), amalgam (3.3%), composite fillings (2.2%), composite inlays/onlays (2%), gold inlays/onlays (1.2%), CEREC inlays/onlays (1.1%).13 A high success rate was also reported for overlays. Studies on 286 restorations of this type (Vita Mark II ceramic, CEREC technique) cemented in 244 patients were conducted between 2003 and 2004. The follow-up time was 93 months, and the success rate was 96.5%. A slightly increased risk was found in

the case of premolars as compared to molars, and in the mandible as compared to the maxilla.14 12.2.2 Crowns With the development of the CEREC 2 system, besides inlays and veneers, crowns could also be manufactured (Figs 12-9 and 12-10). Studies on various clinical cases have been conducted, ranging from crown application on vital, short, and devitalized teeth, to an extension of the preparation into the pulp chamber (endocrowns). The highest success rate was documented in the case of conventional preparations (97%), followed by crowns on short teeth (92.9%). The success rate of crowns extended into the pulp chamber was satisfactory in the case of molars (87.1%) and poor in the case of premolars (68.8%). The study comprised 65 all-ceramic Vita Mark II crowns, which were followed up for a period of 4 years.15,16 Other authors reported similar results, namely success rates of 97% regarding margin integrity, absence of secondary cavities, discoloring, and anatomical shape preservation.17

Fig 12-11 Custom-made veneer.

Fig 12-12 Custom-made crown.

12.2.3 Ceramic veneers As a rule, ceramic veneers are synonymous with dental esthetics, for patients at any rate. Even with technologies such as optical scanning and digital milling, models and wax-up preparations when communicating with the patient, and mock-up provisional restorations in ultraconservative dentistry, should not be overlooked. In the case of chairside CAD/CAM systems, the design is solely the dentist’s responsibility. Both veneers and crowns for the front teeth must be custom-made in order to meet esthetic requirements. Until the dentist has acquired sufficient experience, collaboration with the dental technician is recommended for the best possible esthetic end result (Figs 12-11 and 12-12). Scientific research was conducted over a period of 9.5 years on veneers and partial crowns on anterior teeth that had been produced by the CEREC 1 and CEREC 2 systems using Vita Mark II (mainly) and Ivoclar ProCad: 509 of them had been bonded to natural teeth, and 108 had been used to replace previous restorations. The restorations attached to previously restored teeth had a success rate of 91%, while those placed on the natural teeth showed a success rate of 94%.18 Another study carried out over 9 years on 715 CAD/CAM-generated veneers showed a 98% success rate; 97.3% of the teeth remained vital, and 96.2% were asymptomatic the entire time. CAD/CAM veneers achieved comparable clinical results to results reported for laboratory processed veneers.19 The aforementioned studies are evidence of the long-term success of CAD/CAM-generated restorations. Nonetheless, anterior teeth veneers and crowns should be approached only after the dentist has become accustomed to CAD/CAM technology, and in collaboration with the

dental technician. 12.2.4 Bridges The manufacturers of materials for CAD/CAM systems have to date not officially recommended short-term bridge restorations made of provisional blocks. CAD already allows the fabrication of up to four-unit bridges by milling a lithium disilicate ceramic block placed over a zirconia framework (Fig 12-13), but teamwork with the dental laboratory is mandatory. Three-unit bridges have recently been developed for anterior teeth (e.max, Ivoclar Vivadent). 12.2.5 Surgical guides The growing use of dental implants has been accompanied by a corresponding development in implant planning procedures. Computer-guided planning is based on cone-beam computed tomography (CBCT), which provides a 3D image of the maxillary bone structures. The data supplied by the planning process can be used in clinical practice for the fabrication of surgical guides. Special software programs are employed to correlate the 3D CBCT images with the 3D scan image of the dental and gingival structures. The result helps to create surgical guides that allow the immediate loading of dental implants, eliminating the need for flap elevation (Figs 12-14 to 12-16). They can be simple and used only in the early stages of surgical intervention, or they can be used up to the stage of loading the implant through the surgical guide.

Fig 12-13 CAD technology-generated bridge.

Surgical guides can be outsourced to specialized centers where the CBCT scan and study

models are sent (indicated chiefly in case of multiple implants, due to the rather high cost of the guides), or produced in offices equipped with CBCT and CAD/CAM systems that are able to process the data – indicated in the case of small dental gaps, when one to three implants are needed, and the presence of neighboring teeth is required. However, the existing technology does not allow in-office manufacturing of guides, but of each implant separately – there cannot be two surgical guides in one milled block, even in the case of contiguous implants.

Fig 12-14 Surgical guide.

Fig 12-15 Surgical guide.

Fig 12-16 Preview of the final status. (Image courtesy of Sirona.)

12.3 THE ESTHETICS OF IN-OFFICE CAD/CAM RESTORATIONS Stain and glaze systems fabricated by manufacturers of ceramic materials can be used to personalize inlays, onlays, and dental crowns in the lateral area (Fig 12-17). Obviously, there must be an in-office ceramic furnace capable of processing the ceramic. Nevertheless, customization is not always required when taking into consideration the structure and properties of some available ceramic materials, which display different degrees of translucency, brightness, and shades. Certain ceramics (eg, feldspathic porcelain) are very easy to finish and polish, so that the final result is pleasant without the need for shade customization. According to the California Dental Association, 87% of the restorations are regarded as esthetically good or even excellent, requiring no glazing or personalization.20 The situation is completely different with anterior teeth restorations, when glazing and shade customization by painting are sometimes not enough, and dental porcelain needs to be applied on the previously prepared incisal area. In such circumstances, traditional impression techniques and stone casts are necessary. Before bonding, the internal surface of very thin veneers may well be painted (Figs 12-18 to 12-20).

Fig 12-17 Inlay color customization.

Figs 12-18 to 12-20 Painting the internal surface of the veneer.

12.4 MATERIALS USED IN CHAIRSIDE CAD/CAM TECHNOLOGY Introduction After 1987, computer-aided manufacturing and finishing technologies made the industrial fabrication of ceramic blocks possible. The use of CAD/CAM systems in dentistry and dental technology has become a common constitutive element of prosthetic restoration manufacturing. The list of ceramic materials for processing by CAD/CAM devices depends on the respective milling machine. Some milling machines are specifically designed for the production of zirconia frames, while others cover the complete palette of ceramic materials, from glass ceramics to infiltration ceramics and oxide high-performance ceramics. Nowadays, the following standard ceramic materials for processing by CAD/CAM systems are available:21 • Silica-based ceramics (a glassy matrix dental ceramic): – Fine-particle feldspar ceramics. – Leucite-reinforced ceramics. – Lithium disilicate ceramics. • Infiltration ceramics: – In-Ceram Alumina (Al2O3). – In-Ceram Zirconia (Al2O3, ZrO2). – In-Ceram Spinell (MgAl2O4). • Oxide crystalline ceramics: – Zirconium dioxide. – Aluminum oxide. This section deals only with silica-based ceramics, which are particularly well suited to chairside CAD/CAM systems. From among grindable silica-based ceramic blocks, one may choose feldspathic porcelain blocks (eg, Vita Mark II, Vita), leucite-reinforced (eg, Empress CAD, Ivoclar Vivadent), and lithium disilicate ceramic blocks (eg, IPS e.max CAD, Ivoclar Vivadent). As a result of their relatively high proportion of glass, these ceramics are, in contrast to oxide ceramics, etchable

with hydrofluoric acid, and can thus be inserted very well using adhesive systems. The currently available ceramic blocks can be mono- or polychromatic. 12.4.1 VITABLOCS Vita is the most experienced manufacturer of ceramic blocks for CAD/CAM systems. Since the CEREC system was introduced to the market in 1985, VITABLOC ceramics have displayed a success rate of 92% (studies available over a 5-year period).22 Table 12.4-1 A selection of monochromatic glass ceramic blocks.

Ceramic Manufacturer Type of block name ceramic material

Clinical indications

VITABLOCS Mark II

Vita

Feldspathic porcelain Inlays, onlays, veneers, crowns

CEREC Blocs

Sirona

Feldspathic porcelain Inlay, onlays, veneers, crowns

IPS Empress CAD

Ivoclar Vivadent

Leucite-reinforced ceramic

Inlay, onlays, veneers, crowns

IPS e.max CAD

Ivoclar Vivadent

Lithium disilicate ceramic

Crowns, telescopes, veneers, inlays, minimally invasive onlays, implant superstructures, 3- to 4-unit bridges CAD-on technique

Fig 12-21 VITABLOCS Mark II. (Image courtesy of Vita.)

Fig 12-22 CEREC Bloc. (Image courtesy of Sirona.)

Fig 12-23 IPS Empress CAD. (Image courtesy of Ivoclar Vivadent.)

Fig 12-24 IPS e.max CAD. (Image courtesy of Ivoclar Vivadent.) Table 12.4-2 A selection of multi-colored layer blocks.

Ceramic block name Manufacturer Type of ceramic

Clinical indications

VITABLOCS Triluxe

Vita

Polychromatic feldspathic porcelain

Inlays, onlays, veneers, crowns

VITABLOCS Triluxe Forte

Vita

Polychromatic feldspathic porcelain*

Inlays, onlays, veneers, crowns

VITABLOCS Real Life

Vita

Polychromatic feldspathic porcelain

Inlays, onlays, veneers, crowns

CEREC Blocs PC

Sirona

Polychromatic feldspathic porcelain

Inlays, onlays, veneers, crowns

IPS Empress CAD Multi

Ivoclar Vivadent

Leucite-reinforced ceramics; natural shades

Inlays, onlays, veneers, crowns

* VITABLOCS Triluxe Forte feature finer nuances of shade transition, with more intense color saturation, increased fluorescence in the cervical area, and more transparency in the incisal area.

VITABLOCS Mark II and CEREC Blocs are made of fine-structure feldspar ceramics, and their abrasive properties are similar to those of natural enamel. They are highly translucent and, due to their exceptional polishing properties, most often do not require glazing (Figs 1221 to 12-22). Besides the properties described for VITABLOCS Mark II, VITABLOCS Triluxe has three layers with different degrees of color saturation in one block, thus being more likely to replicate tooth structure in terms of translucency and color saturation.

VITABLOCS Triluxe Forte display softer nuances of color transition from the enamel to the neck, with enhanced emphasis on color shades and translucency (Fig 12-25). VITABLOCS Real Life display inside individualization of color shades, which enables placing the final restoration during the milling phase so as to fully cover the prepared abutment with a dentin-simulating ceramic structure. The flexural strength of the aforementioned blocks is 150 MPa (Fig 12-26).

Fig 12-25 VITABLOCS Triluxe. (Image courtesy of Vita.)

Fig 12-26 VITABLOCS Real Life. (Image courtesy of Vita.)

Fig 12-27 IPS Empress CAD Multi. (Image courtesy of Ivoclar Vivadent.)

12.4.2 IPS Empress CAD IPS Empress CAD is a leucite-reinforced glass ceramic with a flexural strength of 160 MPa and exceptional color properties. Therefore, the blocks may be chosen according to the preferred translucency (high translucency or low translucency) and shade in the classical A to D shade guide, as well as shades for whitened teeth. High-translucency blocks are mainly used for smaller restorations (inlays, onlays) due to their true-to-nature chameleon effect, whereas low-translucency blocks are suitable for the fabrication of crowns, due to their chroma and brightness values (Figs 12-23 and 12-27). Besides the aforementioned benefits, IPS Empress CAD Multi are polychromatic, with high brightness and translucency values. They also have a lifelike chameleon effect and fluorescence similar to the neighboring dental structures. IPS e.max CAD blocks are made of lithium disilicate and have a flexural strength of 360 MPa. They combine strength, efficiency, and esthetics, making them chiefly suited for lateral crowns and up to four-unit posterior bridges (in the latter case the CAD-on technique is used, by which the ceramic superstructure is milled over a previously fabricated zirconium dioxide framework) (Fig 12-24). They have exceptional color stability, high abrasion resistance over time, and excellent esthetics, which makes them widely popular.23 Beside the option of choosing between high-translucency and low-translucency blocks described for IPS Empress CAD, there are also medium-opacity blocks, which are used to mask colored abutments. Due to their properties of strength and brightness, IPS e.max Impulse blocks are best suited for partial crowns and very thin veneers. It should be taken into consideration that, in contrast with the other materials that do not go through a crystallization stage, these blocks do go through a crystallization stage of about 30 mins after milling. They initially exhibit a bluish color and are better milled in their “soft” state. Consequently, an in-office ceramic furnace is required. Any restoration fabricated from the aforementioned materials can be bonded because they react with hydrofluoric acid. Furthermore, blocks of various sizes are available, according to clinical indications. 12.4.3 Prosthetic restorations Another category of prosthetic restorations produced with chairside CAD/CAM technology are

provisional restorations. Either single crowns or bridges, sometimes for longer-wear periods, can be fabricated from various materials supplied by manufacturers (eg, Vita CAD Temp Monocolor or Multricolor, with a flexural strength of 80 MPa, or Telio CAD, Ivoclar Vivadent, to be used for bridges with up to two pontics, and wear periods of up to 12 months) (Fig 12-28). New materials have recently been developed, such as nanoceramic, supplied by 3M ESPE, and Vita Enamic, fabricated by Vita. Nanoceramic is a mixture of composite resin and ceramic (Fig 12-29). Like a composite, it does not break and is fracture resistant, at the same time preserving its shine for a long-term esthetic appearance. The material does not require glazing after milling because it can be polished. Its flexural strength is 200 MPa, higher than that of the previously described materials (except for IPS e.max CAD, which requires crystallization after milling). The material is best suited for crowns, implants, inlays, onlays, and veneers. The product warranty period is limited to 10 years. Vita Enamic is a hybrid ceramic with a dual network structure, the dominant ceramic network being reinforced by a polymer network, with each network penetrating the other to create a hybrid material that exhibits the positive characteristics of both a ceramic and a composite. This material is perfectly suited for crown restorations in the posterior area and minimally invasive restorations (Fig 12-30).

Fig 12-28 Telio CAD. (Image courtesy of Ivoclar Vivadent.)

Fig 12-29 Nanoceramic crown. (Image courtesy of 3M ESPE.)

Fig 12-30 Vita Enamic crown.

Vita Suprinity is a zirconia-reinforced lithium silicate glass ceramic, with an average flexural strength of 494.5 MPa, which indicates this material for the fabrication of inlays, onlays, partial crowns, veneers, anterior and posterior crowns, and anterior and posterior single-tooth restorations on implant abutments. Crystallization is required after the milling process, following which the material can be individualized or characterized with special ceramic materials (Figs 12-31a and 12-31b). Conclusion In conclusion, we believe that due to its undeniable benefits, CAD/CAM technology will become more and more part of in-office daily routine, whether limited to optical impression or associated with a milling machine. As the systems diversify and new manufacturers and materials emerge on the market, the presently high cost of such systems will be reduced while at the same time the spectrum of clinical indications will expand.

Fig 12-31 a Vita Suprinity block.

Fig 12-31 b Vita Suprinity crown after crystallization and characterization.

REFERENCES 1. Beuer F, Schweiger J, Edelhoff D. Digital dentistry: An overview of recent developments for CAD/CAM generated restorations. Br Dent J 2008;204:505–511. 2. Van der Meer WJ, Andriessen FS, Wismeijer D, Ren Y. Application of intra-oral dental scanners in the digital workflow of implantology. PLoS One 2012;7(8):e43312. doi:10.1371/journal.pone.0043312. 3. Johnson GH, Craig RG. Accuracy of four types of rubber impression materials compared with time of pour and a repeat pour of models. J Prosthet Dent 1985:53:484–490. 4. Millstein PL. Determining the accuracy of gypsum casts made from type IV dental stone. J Oral Rehabil 1992;19:239–243. 5. Sahin S, Çehreli MC. The significance of passive framework fit in implant prosthodontics: Current status. Implant Dent 2001;10:85–92. 6. Kim Y, Oh TJ, Misch CE, Wang HL. Occlusal considerations in implant therapy: Clinical guidelines with biomechanical rationale. Clin Oral Implants Res 2005;16:26–35. 7. Logozzo S, Franceschini G, Kilpelä A, Caponi M, Governi L, Blois L. A comparative analysis of intraoral 3D digital scanners for restorative dentistry. J Med Internet Res 2011;5:117–141. 8. Schenk O. The new acquisition unit Cerec AC. Int J Comput Dent 2009;12:41–46. 9. Kachalia PR, Geissberger MJ. Dentistry a la carte: In-office CAD/CAM technology. J Calif Dent Assoc 2010;38:323–330. 10. Syrek A, Reich G, Ranftl D, et al. Clinical evaluation of all-ceramic crowns fabricated from intraoral digital impressions based on the principle of active wavefront sampling. J Dent 2010;38:553–559. 11. Posselt A, Kerschbaum T. Longevity of 2328 chairside Cerec inlays and onlays. Int J Comput Dent 2003;6:231–248. 12. Arnetzl G. Different ceramic technologies in a clinical long-term comparison. In: Mörmann WH (ed). State of the Art of CAD/CAM Restorations, 20 Years of CEREC. Berlin: Quintessence, 2006:65–72. 13. Hickel R, Manhart J. Longevity of restorations in posterior teeth and reasons for failure. J Adhes Dent 2001;3:45–64. 14. Arnetzl GV, Arnetzl G. Reliability of nonretentive all ceramic CAD/CAM overlays. Int J Comput Dent 2012;3:185–196. 15. Bindl A. Survival of ceramic computer-aided design/manufacturing crowns bonded to preparations with reduced macroretention geometry. Int J Prost Odont 2005;18:219–224. 16. Otto T. Computer-aided direct all-ceramic crowns: 4 year results. In: Mörmann WH (ed). State of the Art of CAD/CAM Restorations, 20 Years of CEREC. Berlin: Quintessence, 2006. 17. Reich SM, Wichmann M, Rinne H, Shortall A. Clinical performance of large, all-ceramic CAD/CAM generated restorations after three years: A pilot study. J Am Dent Assoc 2004;135:605–612. 18. Wiedhahn K. CEREC veneers: Esthetics and longevity. In: Mörmann WH (ed). State of the Art of CAD/CAM Restorations, 20 Years of CEREC. Berlin: Quintessence, 2006:101–112. 19. Wiedhahn K, Kerschbaum T, Fasbinder DF. Clinical long-term results with 617 Cerec veneers: A nine-year report. Int J Comput Dent 2005;8:233–246. 20. Sjögren G, Molin M. A 10-year prospective evaluation of CAD/CAM-manufactured (CEREC) ceramic inlays

cemented with a chemically cured or dual-cured resin composite. Int J Prosthodont 2004;17:241–246. 21. Beuer F, Schweiger J. CAD in practice. Dig Dent Technol 2011;2:91–95. 22. Molin MK, Karlsson SL. A randomized 5-year clinical evaluation of 3 ceramic inlay systems. Int J Prosthodont 2000;13:194–200. 23. Liu PR, Essig ME. Panorama of dental CAD/CAM restorative systems. Compend Contin Educ Dent 2008;29:482–486.

LUCIAN CHIRILĂ

Chapter XIII DENTAL IMPLANTS PLACED IN THE ESTHETIC ZONE

13.1 Introduction Oral prosthetic restoration on dental implants is a predictable procedure in most cases. Current implantology is concerned not only with the long-term success of dental implants (survival on the arch, or bone integration), but also with the functional and esthetic outcomes of the oral rehabilitation on dental implants (the prosthetic restoration and its dentomaxillofacial harmony). The esthetic aspect of the treatment is growing in importance, in response to the increasing demands of patients receiving dental implants. Placement of implants, especially in cases of partial edentation, requires functional tridimensional location identification, which ensures long-term implant survival, at the same time requiring the consolidation of the bone and gum structures, which ensures long-term esthetic results. Esthetics and functionality should go hand in hand in all dental and periodontal zones, not just in some. From the classical point of view, the esthetic zone is the anterior maxilla, although most of the upper dentoperiodantal structures actually participate in overall facial harmony. The prosthetic restorations in this area are a challenge for the oral rehabilitation team, especially because of the maximum involvement in the general physiognomic aspect of the patient. The esthetic aspect requires a correlation of the hard tissue parameters and the soft tissue that need to be harmonized. Both dental and gingival esthetics interlace for a nice smile and a balanced, harmonious facial appearance. The clinician should be well practiced and also consider the gingival factors (morphology, texture, color, shape, and size).2,5 Implicitly, the bony support must be assessed for quantity and quality. The maxillary bone is both the infrastructure on which the gum develops and shapes, and the receiver of the dental implant. 13.2 Establishing the diagnosis and planning the therapeutic sequence The therapeutic outcome in uni- or multidental upper anterior edentation is a challenge, especially when several teeth are missing. Preserving or reconstructing a gingival morphology that gives the illusion of natural teeth is hard, and very often small technical slips will ruin the esthetic outcome and lead to patient dissatisfaction.1,2 A good esthetic result of prosthetic reconstructions on implants placed in esthetic zones

depends on a judicious preoperative diagnosis and adequate therapeutic planning. Preoperative anamnesis is important both for the patient assessment and for his/her esthetic expectations. The patient should undergo an overall health assessment. Possible medical problems that could contraindicate surgical operations could be evidenced. The patient’s dental state and history of dental and periodontal conditions should be assessed, and an oral and cervicofacial examination should be performed. The results of the imaging tests (dental radiographs, cone beam computer tomography [CBCT] scans) are analyzed and evaluated in the light of the clinical findings and esthetic expectations. Study models and oral and facial photos will be taken to complete the perioperative documentation. This comprehensive examination may establish a number of esthetic risk factors for the prosthetic restoration supported by dental implants.6,7,8 A number of general pathological states, parafunctions (eg, bruxism), smoking, or poor oral hygiene should also be taken into account as potential risk factors for the functional and esthetic outcome of implants in the esthetic zone. The ideal placement of implants, and the optimal prosthetic result, requires the evaluation of the edentulous space in relation to the facial, dental and periodontal examination.3 The success of the bone integration involves achieving a balance between functional and esthetic factors, with an asymptomatic interface between bone and implant and permanently healthy periimplant gingival tissues.9,10 13.3 Criteria of successful implants9 Absence of implant mobility. Radiograph examination does not evidence peri-implant radiotransparency. Vertical bone lysis is less than 0.2 mm/year after the first year of functional prosthesis. No signs of gum inflammation, bone infection, pain, neuropathy, or paresthesia. A success rate of 85% after 5 years and 80% after 10 years are the minimum accepted criteria.

Another objective of implant treatment is to preserve the bony and gummy structures and fulfill the esthetic purpose in accordance with the patient’s objective and subjective demands.7 The predictability of the esthetic outcome in the anterior maxillary zone depends on a number of factors, among which the most important are the esthetic parameters referring to the smile line, dental position, status, and morphology of the crowns and roots of neighboring teeth, the gingival biotype, the level of gum recession in the edentation, the morphology of the

bone support and its spatial position, and the implant position.3,5,11,21 13.3.1 The smile line The shape of the upper lip and its relation to the dental and periodontal structures are extremely important in the assessment of dental esthetics. This relationship is the starting point for esthetic restorations in the anterior maxillary zone. At the same time, this aspect determines the therapeutic methods for the reconstruction of dentoperiodontal harmony.6 On average, a smile reveals about 75% to 100% of the anterior incisors’ height and adjacent gum. If the upper lip line is lower, less than 75% of the incisors’ height will show (Fig 13-1).12 Clearly, a high smile line calls for more attention to esthetics than one revealing less than 75% of the teeth. In a high upper lip line, the smile will uncover the tooth neck margins and the gum, and the gum-, tooth relation is an important esthetic factor in the maxillary anterior zone. The line of the lower lip is an element of facial harmony, its relationship with the maxillary incisors allowing the assessment of the curvature and inclination of the incisal plane, the position of the incisal margin, and the vestibular inclination of the anterior teeth.

Fig 13-1 The position of the lower margin of the upper lip generally reveals the dental papillae and 75% to 100% of the anterior teeth. This pattern is considered the “average smile line”, present in about 70% of the population.

Fig 13-2 The insufficient mesiodistal space is corrected orthodontically, thus preventing the insertion of the implant too close to the interproximal bone in the risk area. The degree of orthodontic modification of this space depends on the size of the analogous tooth and the minimal mesiodistal space necessary to insert an implant (6 to 7 mm).

In the case of a relaxed smile, the incisal margin of the maxillary anterior teeth should follow the line of the lower lip. If the incisal margin is too anterior or posterior in relation to the internal margin of the red lip portion, there is a supposition of abnormality.12 The mucogingival line is also assessed, and a marked pattern is corrected by gingivectomy. The lateral incisor may be at a slightly different level from the central incisor, or have the same level. The patient should be informed of an exaggeration of the uneven level or asymmetries of the gum line. Even if not perceived, the existing gum line will be a reference for the esthetic restoration. The anterior teeth provide the support for the upper lip. If there are many anterior teeth missing, patients may request a more labial position of the prosthetic reconstruction in order to have more labial support. Besides the fact that the general esthetic effect may be affected, the positioning of the teeth outside the neutral muscular balance zone will cause an abnormal stress on the implant, with repercussions for the bone and gums. The anterior teeth should be situated inside the “functional envelope” determined by the muscular balance between the lip and tongue. Repercussions are felt at the functional, esthetic, and phonetic levels, but also at the morphological level. 13.3.2 The position of the remaining teeth and roots, and the periodontal condition of the teeth that limit the edentulous zone The remaining teeth should be assessed clinically and radiologically in order to establish their relation with the edentulous space. The position of the roots inclined toward the edentation

limit the correct placement of the implant. Distancing the implant from the interproximal space in order to avoid contact with the neighboring root will place it outside the ideal site, and may limit the spontaneous recovery of the dental papillae by provisional crowns. These patients should undergo preoperative orthodontic treatment (Fig 13-2). An important factor in the prediction of the therapeutic and esthetic outcome is the level of the interproximal bone. Teeth with marked lyses of the proximal bony septum represent an increased risk for the esthetic result, and even for the success of the implant. Local vertical augmentations of the interproximal bone are not too predictable due to the local conditions (avascular root or sepsis due to the impossibility of sealing the periodontal space). More predictable and recommended are augmentations of the soft tissues, by soft tissue grafts (Figs 13-3a and 13-3b).

Fig 13-3 a Good esthetic appearance 3 years after prosthetic restoration on implants at 12 and 22.

Fig 13-3 b Radiograph showing the preserved septum of the limiting teeth and support of the interdental papillae. The contact point is well placed for the stability of the papillae and the free gum margin.

Fig 13-4 Normal shape of the gum line, level and shape of the interdental papillae, and dental contact point in healthy dentoperiodontal structures.

13.3.3 The shape of the gum line and the interdental papillae The gum line may have a normal, marked, or flat shape, usually following the bone structure. In the case of a normal and healthy periodontium, the underlying bone is situated 2 mm below the cementoenamel junction (CEJ), and at 3.5 mm at the central incisor. Thus, in the case of a markedly high gum line, there will be more gingival tissue interproximally, and more coronary positioned, than in the vestibular tooth neck area. The flat gum line is easier to reproduce as it follows the bone level more closely.11 The interdental papilla is supported by the proximal bone at the level of the teeth, limiting the edentulous space. The height of both the interproximal bone and the edentulous spaces determines the esthetic outcome. The bone in the edentulous area should be at a physiological distance of 2 to 3 mm from the gingival margin (Fig 13-4).4,16,21 13.3.4 The periodontal biotype This is one of the essential parameters determining the esthetic outcome of dental restorations in the maxillary anterior zone. The periodontal biotype determines the surgical approach and establishes the esthetic limitations. Two main periodontal biotypes are described: thinscalloped and thick-flat.22 In the case of the thin-scalloped biotype, the periodontal architecture is pronounced and frail. It is characterized by bone fenestrations and minimal gingival attachments. Surgical operations often entail gum recession. Minimal surgical interventions are recommended, and the flaps created should not touch the blood supply in the implanted bone bed.6,11

In a case such as this, the patient should be informed regarding possible gum and bone recessions and the necessity of augmentation procedures. One way to prevent such periodontal reactions is to place the implant more palatally and the implant neck more apically. In the case of a thick-flat, firm biotype, the periodontal tissue mass is fibrous and dense, with an increased amount of keratinized gum. The periodontal tissue bears trauma better, and gum recession is minimal. This periodontal type reacts to trauma by forming periodontal pockets (Figs 13-5a to 13-5c).6,11,13 Also, postoperative scars are more obvious, which might affect the final esthetic appearance. Nevertheless, long-term tissue stability is predictable, once the esthetic objectives have been achieved. 13.3.5 Bone morphology of the alveolar crest The bony support is one of the defining factors of the success of implant therapy, as well as its long-term survival and esthetic outcome. The ideal tridimensional configuration of the alveolar ridge ensures a functional and stable placement of dental implants. At the same time, adequate bone morphology represents an infrastructure that helps preserve the soft tissues sufficiently to ensure esthetic success. Thus, besides the bone integration of the implants, there is also the premise of a well-located fibromucosa, which limits the prospect of gum recession.

Fig 13-5 a Coronary restoration on an implant (21). Firm periodontal biotype, with long-term tissue stability (9 years after prosthesis).

Fig 13-5 b Preserved tissue morphology, despite the fact that the neighboring teeth present signs of gum recession.

Fig 13-5 c Correct tridimensional positioning and observance of the biomechanical principles favored the long-term esthetic outcome.

If the bone anatomy and/or volume are inadequate, additional surgical procedures are necessary to restore the lost bone contour and volume. The patient must be informed and understand the therapeutic requirements for bone and soft tissue augmentation before the treatment so as to obtain the expected results (Figs 13-6a to 13-6d). The bone architecture is analyzed tridimensionally, clinically, and by imaging. Current imaging techniques, such as cone beam scanning, have become accessible, and are very useful in tridimensional bone analysis. Clinical examination should not be dismissed as it plays a major role in establishing diagnosis and therapy. As the bony substrate is a basis for gum volume and position, often bone augmentation also requires soft tissue augmentation. This aspect is particularly important in vertical bone defects, which are less predictable and more difficult to manage. The loss of bone volume may also be assessed before extraction. Kois11,13 considers that the

level of the anterior cervical bony ridge of the tooth in relation to the free gum margin is defining in the assessment of the bone deficit that will occur after extraction. The greater the distance, the greater the bone deficit will be after invasive procedures. Generally, the vertical distance between the free gum margin and the bone ridge is 3 mm, and a 1 mm bone resorption may be expected after the implant placement immediately after extraction. A distance larger than 3 mm may determine greater resorption. Thus, measurement before the operation may help the decision: a distance of more than 3 mm of the dentogingival complex requires orthodontic extrusion before the extraction.

Fig 13-6 a Lateral incisor 22 has grade II to III mobility, lyses of the vestibular cortical bone, and marked enlargement of the marginal periodontal space, determined by the longitudinal fracture of the root.

Fig 13-6 b The clinical view of the alveolar process 4 months after guided bone regeneration.

Fig 13-6 c Tridimensional determination of the optimal direction of implant insertion.

Fig 13-6 d One-stage implant insertion and surgical construction of interdental papillae.

At the same time, the bone volume at the dental interproximal level is also assessed. This volume plays a critical part in the maintenance of the interdental papillae. The interproximal space is usually filled by gingival tissue. An important factor is the bone height of the proximal ridge. The better this is represented, the better the papillary support will be, and the interdental papillae will consequently be more stable in time. An important element in the preservation and stability of the papillae is the interdental contact point. If the vertical distance between the contact point and the interproximal bone is 3 to 5 mm, the papilla will fill this space, even if initially it was not constructed, or it was missing. When this distance is 6 mm, the papilla is absent in 45% of cases, while if it is 7 mm, the papilla will not fill the interdental space in 75% of cases.17 The height of the peri-implant papilla in single tooth edentation is independent of the peri-implant bone level, but dependent on the height of the bone proximal to the tooth.18 The spontaneous formation of the dental papilla, dependent on the height of the bone of the tooth near the edentation, is also influenced by the location of the coronary contact point. The

contact point may be a critical element, and it is determined by the crown shape and teeth inclination, as well as by the ability of the dental technician and the prosthodontist’s requirements. From this point of view, it is recommended that provisional acrylic crowns be used for modeling and guiding spontaneous growth of the papillae in the esthetic zones. If the space between the bone substrate and the prosthetic contact point is larger than 5 mm, it is rather unlikely that spontaneous growth of the papillae will occur, the result being the appearance of the so-called “black triangles”. In the case of edentation treated by multiple implants, the distance from the bone ridges to the tip of the papillae is 2 to 4 mm. Thus, the contact point should be placed closer to the crestal bone in order to prevent the formation of “black triangles”. The height of the papillae between crowns placed on two neighboring implants is therefore smaller than when a neighboring tooth is present. The papillary height is thus influenced by the location of the contact point, the space between dental implants, and the crown contour (Fig 13-7).3,16

Fig 13-7 Volume and shape of interdental papillae mainly depend on the level of the interproximal bone and the contact point. When the bone height is good, the altered dental contact point may influence the papilla height in a negative way. In single-tooth edentation, the contact point should be placed at about 5 mm from the bone level to favor papilla formation. A distance over 5 mm will not allow enough gum growth and “black triangles” will appear.

A number of clinical variables also influence the development of interdental papillae: the tip of the interproximal bone ridge between the tooth and the implant; the distance between the

bone ridge and the contact point; the mesiodistal space between the tooth and the implant, or between implants; the reconstructed tooth shape; the surgical techniques of ridge preservation; the periodontal biotype; and the time and quality of soft-tissue development.7 The volume and architecture of the alveolar ridge in the patient expecting an implant in the esthetic zone is analyzed from the point of view of ideal implant positioning. However, the surgeon should take into account the fact that the treatment algorithm chosen for the bone reconstruction, implant placement, or implant uncovering will also affect the volume and structure of the soft tissues, in accordance with the periodontal biotype. Thus, defects perceived as bone defects should be treated as a combination of bony and gingival defects. The restoration work in the esthetic zone must not be confined only to the bone or gum, but should also include compensation of the gum recession and bone resorption of the grafts. An excessive augmentation of the soft tissues is recommended in order to mask the bone and gum deficiencies expected to occur during tissue manipulation or scarring.6 Bone ridge architecture is therefore an extremely important element, but not the only one to be considered when establishing the therapeutic plan, as sometimes happens in current practice. Kois11 established five diagnostic keys for the prediction of the esthetic outcome in anterior maxillary restorations, starting from the clinical observation of the normal postextraction sequelae. The important elements for an optimal esthetic result are the: • Relative position of the tooth. • Gum shape. • Periodontal biotype. • Dental shape. • Position of the bony ridge. The existing position of the anterior tooth to be extracted and replaced by an implant is important and must be analyzed beforehand. This position is analyzed tridimensionally to determine the configuration of the gingival architecture. The alteration of this position will cause alterations of the gingival configuration.11 The vertical position of the tooth, the apex-crown position of the tooth neck margin, may be more apical, more coronal, or ideal. After extraction, the free gum margin will recede at least 2 mm; when the implant is inserted directly after, gum recession will be 1 mm, on average.13,14 From a practical point of view, a tooth in a more crestal position (extruded) is well placed for a prosthetic restoration on the implant, as well as for reduced inherent recession of the gum

after extraction.11 If the tooth is situated in an ideal vertical plane or in a more apical position, gum apical displacement is more obvious. A way to compensate for gum recession is orthodontic extrusion before extraction.11,15 The anteroposterior tooth position may also influence the gingival appearance. A tooth positioned too facially usually presents a thin cortical bone that is prone to collapse, which entails increased gum recession and a marked denivelation of the free gum margin. These clinical situations are candidates for bone and fibrous tissue grafts performed within the esthetic restoration protocol.5,11 Teeth placed lingually usually have a good vestibular cortical bone, with minimal gingival repercussions. The position of the tooth in the mesiodistal plane is assessed in relation to the neighboring teeth and the interdental bony septum necessary for the preservation of the interdental papillae. The presence of a neighboring tooth may be less convenient as the proximal bony septum is under 1.5 mm and it will undergo postextraction resorption, with the subsequent collapse of the interdental papillae.11,16 The interdental bony septum is an important esthetic parameter, a support for the dental papillae, and should not be injured during dental extraction. Its volume is assessed on the radiograph. The crown shape may also often provide an indication of the septum size. An anterior maxillary tooth with a rectangular crown is usually associated with a more delicate septum, prone to early resorption, while a triangular crown will indicate a more robust septum. The mesiodistal dental position has a direct influence on the position of the roots of the teeth limiting the edentation. It is preferable that these roots be made parallel by orthodontic methods before the implantation.16 Another parameter to be evaluated is the interdental space at the levels of the free gum margin and the incisal margin. Teeth with convergent crowns will present a reduced incisal space and a large gingival space. If this difference is not eliminated (orthodontics, polishing of the proximal enamel, or prosthetic restoration), the final restoration on the implant will be unpleasant esthetically because of the lack of papillary compensation at a gingival level (the dental crown on the implant will have “black triangles”). The tooth shape influences peri-implant esthetics. Kois11 considers that the coronary impact is at both an apical and a coronary level in relation to the free gum margin. The tooth shape may be triangular, rectangular, or ovoid. From the point of view of the papillary appearance, a rectangular tooth is more esthetically favorable and predictable as it will present a more

extended contact point and a placement nearer to the bone support, within the 5 mm limit. On the other hand, a triangular tooth will have a more incisal contact point, with increased requirement of papillary height. However, the triangular shape is better from the point of view of the bone crest, ie, the apical position in relation to the free gum margin. A triangular crown will allow the implant to be placed further from the proximal dental bone crest, which will reduce bone lysis. The dental crown should follow the shape of the contralateral tooth. Triangular crowns are attributed by some authors to the thin-scalloped gingival biotype, while rectangular ones are associated with the thick-flat, firm periodontal biotype.6 Thus, from the point of view of the diagnostic keys regarding peri-implant esthetics prediction,11 the minimal esthetic risk factors would be: coronary or lingual tooth position, flat gum line, thick-flat periodontal type, rectangular crown shape, and a high crestal position. On the other hand, a high esthetic risk is indicated by the apical or vestibular dental position, marked gum scallop, thin-scalloped periodontal type, triangular tooth crowns, and a smallvolume alveolar ridge (Figs 13-8a to 13-8f). 13.3.6 The ideal position of implants At the level of the anterior maxilla, the surgical position of the implants is performed tridimensionally. The implant application requires more precision with smaller edentations. In maxillary single-tooth gaps, the positional limitations of the implants are strict. Even a 1 mm deviation may make the difference between esthetic success and failure. Generally, in the 3D positioning of the implant in the esthetic zone, increased attention will be paid to the cervical portion of the implant. The spatial relation of this implant surface with the neighboring teeth or with the ideal position of the missing teeth determined on the study model is analyzed in the transversal (mesiodistal), anteroposterior (vestibulolingual) and vertical (apicocoronal) planes. Another essential parameter in the tridimensional positioning of the implant is the implant angulation, regarded especially from the vestibulolingual plane. An important element, often neglected, is the crown type that will restore the missing anterior teeth and the type of the implant-crown connection (cemented or screwed crown). The initial choice of the connection type and the design of the restoration that will guide the implant placement in the ideal position represent a concept developed by Garber.23 He considers the implant as an apical extension of the dental crown, which, in fact, supports the patient’s perception. This concept is known as restoration-driven implant placement, in contrast with the initial concept of bone-driven implant placement. The restoration-driven concept developed by

Garber allows the implant, especially in the esthetic zone, to be placed where the missing tooth may be restored adequately. The lack of bone and soft tissue in the area considered ideal for the implant will be augmented according to the esthetic purpose and the patient’s expectations. For each spatial dimension there is a “comfort” zone and a “danger” zone.3,21

Fig 13-8 a The central incisor presents a crown-root fracture following a traffic accident, accompanied by a longitudinal root fissure and gum wound. The tooth has a 3-year-old crown-root reconstruction.

Fig 13-8 b Extraction of tooth 11 and immediate insertion of an implant is decided. A CBCT scan evidences the bone structure (which is intact), the direction of the dental root, and the local morphology. An implant simulation is performed to establish intraoperative guidance.

Fig 13-8 c The 3D position of the bone preparation is checked intraoperatively.

Fig 13-8 d Immediate postextraction implantation requires precise preparation and application. The posttraumatic gum wound may be observed. Tissue manipulation is minimal, without gum detachment, to prevent the injury of the bone and soft tissues.

Fig 13-8 e Postoperative radiograph. The implant is inserted in an apicocoronal plane at about 3 mm from the free gum margin and about 1 mm from the crestal margin of the vestibular cortical bone, in order to compensate tissue recession entailed by healing. The gingival structure is shaped by the initial dental crown, remodeled, and bonded.

Fig 13-8 f Postoperative clinical view.

The crestal portion of the implant is placed in the “comfort” zone to provide the necessary infrastructure for the esthetic restoration. The placement in the “danger” zone significantly minimizes the chances of therapeutic success (Figs 13-9a and 13-9b). The mesiodistal positioning should be carefully evaluated. The distance at the cervical crestal level and between teeth (for single-tooth gaps) is considered, especially for incisors, in which alterations may occur due to dental migration entailed by extraction. The limitation of this distance must be corrected orthodontically before the operation. This mesiodistal distance determines the choice of the implant platform. The objective is to place the implant outside the “danger” zone, situated at 1.5 to 2 mm from the root of the neighboring tooth. Too close a placement may cause the lysis of the proximal bone, and the interdental papillae will collapse (Fig 13-10).3,4,7,21 Regarding prosthetic restorations on several implants, the ideal space between two implants is 3 to 4 mm. This space is measured at the crestal level of the implant. The inter-implant space in the upper anterior zone is useful for the preservation of the crestal bone between implants, and the inter-implant papillae. The papilla that grows in the inter-implant area is about 3.5 mm in height, significantly smaller than the 5 mm papilla situated near a natural tooth (Figs 13-11a and 13-11b).16,20 Due to the necessity of the implant placement at least 1.5 to 2 mm from the neighboring teeth, and at least 3 mm from the next implant, the implant platform in the anterior zone should not be too large (wide platform [WP]), and this is also true for postextraction implants. A common mistake is to consider the implant platform to be similar to the mesiodistal size of the tooth to be replaced. What should be borne in mind is that the implant-prosthetic crown represents an esthetic complex with an intermediate element, namely the prosthetic abutment.

Every implant system offers various sizes of this connector, which is usually larger in diameter than the implant itself. The diameter of the prosthetic abutment should be assessed and adapted to the existing mesiodistal space, not to the implant platform. Wheeler and Ash24 established average crown dimensions and tooth neck diameters. Thus, the diameter of the upper central incisor neck is 7 mm, the upper lateral incisor is 4 mm, and the upper canine is 5.5 mm.19

Fig 13-9 a Crown restoration at 12, with good esthetic appearance after 5 years.

Fig 13-9 b Implant placed in the “comfort” zone, and observance of the principles of tridimensional insertion and biomechanics.

Fig 13-10 Correct mesiodistal positioning will preserve the proximal bone septum. The implant shoulder is placed 1.5 to 2 mm from the neighboring teeth roots.

Fig 13-11 a In the case of two neighboring implants, the distance between them should be at least 3 mm.

Fig 13-11 b Interdental papilla is smaller between the crowns on implants than in the adjacent natural tooth. Clinical view of a case after 4 years.

Fig 13-12 The correct placement of the implant platform in the vestibulolingual plane means a position at least 1 mm behind the imaginary line of the emergence area of the future crown. If the implant is too much toward the lips, the esthetic effect is diminished by the creation of an inadequate coronary profile, and the possible “physiological resorption” will reduce the bone support of the frontal free gum margin, leading to gum recession. If the position of the implant shoulder is too much towards the palate, the dental crown will be oversized.

The vestibulolingual position of the implant impacts on the vestibular restoration of the tooth and the proper coronary emergence profile. The anterior margin of the implant platform should be situated 1 mm behind the emergence line of the natural crowns. The reference point may be the enamel-cement junction. From this level, a 2 mm anteroposterior distance is considered a “comfort” zone. By placing the shoulder of the implant behind this level, we enter the second danger zone of the vestibulolingual plane (Fig 13-12).3 If the implant is placed too far toward the lips, there is the risk of vestibular bone dehiscence and gum recession. At the same time, prosthetic restoration will be more difficult. This could be avoided by maintaining a 1 mm thickness of vestibular cortical bone. If the implant is placed too far toward the palate, the crown will have to be overcontoured to obtain an esthetic appearance, which will impact negatively on oral hygiene. Bone and gingival tissue stability is obtained when at least 1 mm of the vestibular cortical bone is retained. Priest20 recommends that the implant center should be placed at least 3 mm from the imaginary vestibular margin of the future crown (for a regular platform [RP] implant 4 mm in diameter). This way, the prosthetic platform will have 1 mm space on the labial side, though it should not exceed 2 mm. A palatal placement of the implant is less harmful from the esthetic and biomechanical viewpoints than a vestibular placement. In fact, in the case of patients with a thin-scalloped periodontal biotype, a more palatal placement is indicated in order to prevent the recession of vestibular bone and gum. The implant is positioned vertically (apex-crown) at 2 to 3 mm from the free gingival margin of the future prosthetic restoration.3,4,20,21

In order to visualize the planned margin of the crown or the future free gum margin intraoperatively, a surgical guidance should be used, which will evidence these aspects. An equally useful reference point, especially in single-tooth edentation, is the CEJ, which may be used in establishing the apical level of the implant. However, this landmark should be used cautiously as the level of the junction may vary, especially at the lateral incisor, where it may be more toward the crown as compared to the central incisor or the canine (Fig 13-13).3 The reason the implant is placed approximately 3 mm deep from the free gum margin is to make a biological width of about 3 mm. It is also to mask the prosthetic pin and the contact margin between the pin and the crown, as well as to create a work space, allowing the technician to realize the coronary emergence profile. At the same time, the potential postimplant tissue recession will be compensated for.20

Fig 13-13 Correct apex-crown placement of the implant. The implant platform is about 2 to 3 mm from the CEJ or from the neck margin of the future crown. The implant placed too apically may lead to excessive bone lysis and subsequent gingival collapse, though it initially provides a better esthetic appearance. If it is positioned too coronally, the implant or pin metal will be visible through the mucosa.

Fig 13-14 a Deep apex-crown implant placement.

Fig 13-14 b The esthetic effect is compromised. The firm periodontal biotype favors visible scars, while gum recession is marked by the bone lysis of the vestibular bone, determined by the too-deep implant insertion on the apex-crown axis.

Some authors consider that a deeper placement of the implant neck will ensure better esthetics, and they recommend a deeper set of implants with a narrow platform (NP), in order to leave work space for the technician to achieve the coronary profile emergence, though this aspect will have negative effects on the tissue health. The countersinking drills increase the risk of bone resorption (Figs 13-14a and 13-14b).7,18 The angle of the implant is the fourth parameter to consider in the ideal tridimensional positioning of implants in the anterior maxillary zone. Though at first sight the implant should logically follow the root angle of the tooth replaced or the root inclination of the neighboring teeth (especially in single-tooth gaps), this is not possible in the ideal implant position. Usually, the implant should be inclined so its shoulder (the crestal platform area) is more toward the palate than the projection of the coronary portion. This position will allow the natural and esthetic creation of the coronary emergence profile. Thus, the implant apex will be more vestibular than the tooth apex (Fig 13-15). Priest20 suggests that the implant axis coincides with the palatal incisal margin of the prosthetic crown. This angle will provide an esthetic emergence profile. At the same time, it prevents too palatal a position of the implant, which would determine a marked convex gum profile and coronary overcontour. Too vestibular a placement will result in a thin bony contour and a frail gingival profile predisposed to recession. The implant angle and placement is restorative-driven, and this concept should be adopted for the esthetic zone. If a cemented crown is decided, the implant axis will be oriented with the incisal margin, while for a screwed crown the implant axis will coincide with the crown cingulum.1,3,4,7,20,21 This aspect implies that the practitioner’s prosthetic decision has already

been made at the time of implant insertion. It is recommended that the implant in the esthetic zone should be angled 5 to 10 degrees more lingually than the position of the dental roots replaced (Fig 13-16).14 The recommendation was initially made in order to obtain a vestibular bone thickness over 1.5 to 2 mm, given the “physiological” resorption that often follows after the loading of two-part implants. However, the lingual inclination of up to 10 degrees eliminates the exact overlap of the implant axis on the replaced root axis, and allows the optimal integration of the tridimensional implant position concept and prosthetic esthetic optimization. Moreover, the implant position should also take into account the biomechanical factors and occlusal patterns, the functional load on the implant axis, and the frontal and canine guidance (Fig 13-17).

Fig 13-15 The angle of the implant in the vestibulolingual plane is determined by the positioning of the implant shoulder at least 1 mm from the neck of the future prosthetic crown and the level of neighboring teeth emergence. Also, the implant axis will be in accordance with the axis of the implant-crown prosthetic complex, in order to observe the biomechanical principles. Green: Ideal implant axis for the cemented crown. Blue: Ideal implant axis for the screwed crown.

Fig 13-16 Graphic representation of the implant axis 5 to 10 degrees lingual inclination.

Fig 13-17 A more lingual inclination (yellow line) allows for better management of the coronary emergence profile, the preservation of at least 1 mm vestibular bone, and better tissue stability for the substituted root.

The esthetic restorations of the maxillary anterior zone depend on a number of surgical and prosthetic parameters. The placement of the implant should observe the principles of tridimensional positioning, and the peri-implant gingival contour should be sufficient and stable. The prosthetic crowns should be symmetrical with adjacent teeth or, in the case of multiple anterior restorations, the tooth shape should be in harmony with the facial morphology. The preoperative analysis, as well as a well-designed therapeutic plan, will provide optimal esthetic outcomes. The patient’s expectations may be more predictable if s/he understands the difficulties and risk factors involved, together with the efforts that will be made to fulfill the esthetic objectives. Planning of the therapeutic sequence should be performed with responsibility, assessing the gum and bone conformations in relation to the ideal tridimensional implant placement and optimal crown restoration. The clinical and imaging examinations should be associated with prosthetic models that will evidence the tissue defects and the possibility for bone and soft tissue augmentation. A therapeutic concept strongly recommended for the esthetic zone is the restoration-driven implant placement. It is preferable to place the implants where they will be easily restored, not where there is more bone. In daily practice, unfavorable clinical cases – with increased esthetic and functional risks – are frequently encountered, while patients continue to have unrealistic expectations. All surgical and prosthetic procedures must be established before the onset of the treatment, and the final outcome should be envisaged realistically, without ruling out corrective interventions targeting implant-generated tissue recessions.

REFERENCES 1. Belser UC, Schmid B, Higginbottom F, Buser D. Outcome analysis of implant restorations located in the anterior maxilla: A review of the recent literature. Int J Oral Maxillofac Implants 2004;19(suppl):30–42. 2. Magne P, Belser U. Bonded Porcelain Restorations in the Anterior Dentition. A Biomimetic Approach. Chicago: Quintessence, 2002. 3. Buser D, Martin W, Belser UC. Optimizing esthetics for implant restorations in the anterior maxilla: Anatomic and surgical considerations. Int J Oral Maxillofac Implants 2004;19(suppl):43–61. 4. Belser U, Buser D, Higginbottom F. Consensus statements and recommended clinical procedures regarding esthetics in implant dentistry. Int J Oral Maxillofac Implants 2004;19(suppl):73–74. 5. Jivraj S, Chee W. Treatment planning of implants in the aesthetic zone. Br Dent J 2006;201(2):77–89. 6. Sclar GA. Soft Tissue and Esthetic Considerations in Implant Therapy. Chicago: Quintessence, 2003. 7. Das Neves JB. Esthetics in Implantology: Strategies for Soft and Hard Tissue Therapy. Chicago: Quintessence, 2010. 8. Barbosa F. Patient selection for dental implants. Part 1: Data gathering and diagnosis. J Indiana Dent Assoc 2000;79(1):8–11. 9. Albrektsson T, Zarb G, Worthington P, Eriksson AR. The long-term efficacy on currently used dental implants: A review and proposed criteria of success. Int J Maxillofac Implants 1986;1(1):11–25. 10. Smith DE, Zarb GA. Criteria for success of osseointegrated endosseous implants. J Prosthet Dent 1989;62(5):567–572. 11. Kois JC. Predictable single tooth peri-implant esthetics: Five diagnostic keys. Compend Contin Educ Dent 2004;25(11):895–896. 12. Tjan AH, Miller GD, The JG. Some esthetic factors in a smile. J Prosthet Dent 1984;51(1):24–28. 13. Kois JC. Esthetic extraction site development: the biologic variables. Contemp Esthet Restorative Pract 1998;2:10-17. 14. Saadoun A, LeGall M, Touati B. Selection and ideal tridimensional implant position for soft tissue aesthetics. Pract Periodontics Aesthet Dent 1999;11(9):1063–1072. 15. Salama H, Salama M, Kelly J. The orthodontic-periodontal connection in implant site development. Pract Perio Aesthet Dent 1996;8(9):923–932. 16. Tarnow DP, Cho SC, Wallace SS. The effect of inter-implant distance on the height of inter-implant bone crest. J Periodontol 2000;71(4):546–549. 17. Choquet V, Adriaenssens P, Daelemans P, Tarnow DP, Malevez C. Clinical and radiographic evaluation of the papilla level adjacent to single tooth implants: A retrospective study in the maxillary anterior region. J Periodontol 2001;72(10):164–1371. 18. Kan J, Rungcharassaeng K, Umezu K, Kois JC. Dimensions of peri-implant mucosa: An evaluation of maxillary anterior single implants in humans. J Periodontol 2003;74(4):557–562. 19. Palacci P, Ericsson I. Esthetic Implant Dentistry: Soft and Hard Tissue Management, ed 2. Chicago: Quintessence, 2006. 20. Priest GF. The esthetic challenge of adjacent implants. J Oral Maxillofac Surg 2007;65(suppl 1):2–12. 21. Buser D. Belser U. Wismeijer D. ITI Treatment Guide. Vol 1: Implant Therapy in the Esthetic Zone.

Tooth Replacements. Chicago: Quintessence, 2007. 22. Olsson M, Lindhe J. Periodontal characteristics in individuals with varying form of the upper central incisors. J Clin Periodontol 1991;18:78–82. 23. Garber DA. The esthetic dental implant: Letting restoration be the guide. J Am Dent Assoc 1995;126:319– 325. 24. Wheeler RC, Ash MM. Wheeler’s Dental Anatomy, Physiology and Occlusion. Philadelphia: WB Saunders, 1984.

MARIUS STEIGMANN

Chapter XIV SOFT TISSUE MANAGEMENT FOR AN ESTHETIC ASPECT IN IMPLANT DENTISTRY

14.1 Introduction Stabilization of soft tissues following biological changes induced by extraction is very important for the long-term esthetic outcome. Consequently, the timing of implant insertion and restoration has become a major concern over the past years. Until recently, the osteointegration/function represented the sole objective both in the non-esthetic and esthetic zones. Nowadays, a major focus in the esthetic zone has been placed on the gingival margin and the papillae. The patient’s expectation is a natural-looking tooth, including the surrounding soft tissue. The biological changes after dental extraction may influence the esthetic outcome. In patients with a thick biotype, there are fewer biological alterations after extraction than in patients with a thin biotype. Thus, at the time of extraction, we should establish whether the socket will be preserved, whether the implant will be inserted immediately or later, and whether it will be associated with early or late temporary restorations. The decisions depend on local anatomical factors. Data in literature show that there will always be some degree of bone resorption, regardless of the periodontal biotype. There are few studies of the interproximal bone resorption and vertical soft tissue collapse. However, in our clinical experience, we have found that the interproximal bone presence is an important factor for papillary collapse in a single-tooth environment, depending on the bone mass available and the integrity of the attaching fibers of the adjacent teeth. In the case of multiple implants, the fibrous attachment is lost in the interproximal space and the papilla disappears (this may be prevented by successive extractions). 14.2 Preservation of the alveolus Dental extraction leads to changes in the size of the alveolar ridge contour. The ridge resorption is more marked on the vestibular surface of the post-extractional socket than on the lingual surface. Preservation of the alveolus at the time of tooth removal is supported in order to minimize the resorption of the alveolar ridge horizontally and vertically, and to facilitate the ideal placement of the implant and consequently the esthetic reconstruction. Various approaches have been described to preserve and improve the ridge contour after subsequent dental extractions, including immediate implants. These may be performed using different graft materials, such as allografts, xenografts, or synthetic biomaterials. Two scenarios have been described in the literature for the preservation of the alveola. The majority have been classified according to the shape of the defect, absence or presence of the buccal plate, and

thickness of the vestibular bone plate. However, in the esthetic zone, preserving the alveolus is not enough for the ideal insertion of the implant, from both prosthetic and esthetic points of view. These cases require the so-called alveolar transformation9 in order to create more “bone” buccally than the existing vestibular plate. The grafted bone should be maintained for a long period of time. Consequently, the graft material should be carefully selected (for non- or slow resorption). The thick vestibular plate In the posterior mandibular and maxillary area, the vestibular plate is thicker than 2 mm.2 These cases do not require grafting for alveolar preservation. The expected bony mass volume makes the ideal placement of the implant possible. Case 1: Immediate implant insertion without augmentation

Fig 14-1 Persistent temporary molar on the upper arch.

Fig 14-2 Extraction of temporary molar, its roots are resorbed.

Fig 14-3 a Exploration of the postextraction socket evidences the bone in the interradicular septum. It is possible to insert an implant.

Fig 14-3 b Position is marked for osteotomy.

Fig 14-4 Before the final insertion of the implant, its mesiodistal position is checked to ensure that there is sufficient bone thickness to the neighboring teeth, even after a mild circumferential resorption.

Fig 14-5 Occlusal view of the implant in its final position.

Fig 14-6 The healing cover screw of the implant during the osteointegration period.

Fig 14-7 The alveolus is covered by a resorbable collagen membrane without any other augmentation material. Criss-cross suture to maintain the membrane in place.

Fig 14-8 a Image immediately after provisional restoration performed 8 weeks after implant insertion – two black triangles may be seen in the interproximal spaces. They will disappear and the papillae will reach the contact point.

Fig 14-8 b Image taken 1 year after prosthetic load – the papillae fill the interproximal spaces down to the contact point.

The thin vestibular plate When the vestibular plate is thinner than 2 mm, its partial or total resorption may occur.4,5,6 In order to partially prevent the resorption of a thin vestibular plate or the corresponding volume loss, it is necessary to preserve the alveolus. A technique has been described by Sclar (Bio-Coll technique). He describes the filling of the socket presenting defects in the four walls with xenograft and collagen band. No flap or soft tissue manipulation is necessary.9 Case 2: Immediate implant insertion with augmentation

Fig 14-9 Radiograph evidences a deep caries lesion. The tooth is proposed for removal, as it presents crown and root fractures.

Fig 14-10 Tooth is removed by root separation.

Fig 14-11 The implant insertion point is marked in the interradicular septum.

Fig 14-12 The implant in its final position – an increased amount of autologous bone placed around the implant may be noted.

Fig 14-13 In order to prevent the resorption of the vestibular plate, the empty spaces are filled with xenograft and unresorbable membrane.

Fig 14-14 The membrane is kept in place by a position suture. Closure is not the objective.

Fig 14-15 Radiograph taken 4 months postoperatively shows good bone regeneration.

Fig 14-16 Preservation of buccal-palatal dimensions maintained.

Fig 14-17 Final restoration in situ.

Fig 14-18 Final crown restoration shows an oversized vestibular plate.

The absent vestibular plate When the vestibular plate is missing, the ridge may be preserved using various types of augmentation materials covered by a membrane, and by manipulating soft tissues for primary wound closure. For cases in which the vestibular plate is absent, Elian et al30 describe the ice cone technique: a membrane is introduced under the soft oral tissue, the socket is obturated with graft material and the membrane is folded to cover the alveolus. The membrane is fixed to the palatal soft tissues by sutures. The technique does not require the primary closure of the socket. Other authors8 prefer an early implant and simultaneous graft. At the time of the tooth removal, no graft material is put into the alveolus. After 6 to 8 weeks of healing, the increase in volume of the soft tissue will help cover the graft associated with the implant insertion. Jung has proposed the technique of alveolus sealing and excision of soft tissues, in association or without graft materials, in order to preserve the ridge size.10 When the implants are inserted immediately, one of the above-described scenarios may be applied, by adding an implant into the alveolus. Tooth removal leads to alterations not only of the horizontal dimensions of the hard and soft tissues, but also of the vertical dimensions. The extent of the alterations is important for the treatment planning and restoration of the function and esthetics. In a systematic analysis of the changes of the hard and soft tissues at the level of post-extraction alveloli in humans, data in the literature3–5,6,12 evidences that horizontal bone alterations are followed by anatomical changes of the soft tissues after tooth removal. In the case of a single tooth, soft tissues do not follow bone resorption proportionally to the underlying bone. When several teeth are removed, the soft tissue follows bone resorption proportionally, and consequently

new methods of soft tissue preservation should be applied. There is not much in the literature regarding multiple extractions of adjacent teeth.

14.3 The immediate implant insertion The advantages mentioned in favor of the immediate insertion of the implant are the significant shortening of the healing time, the reduced number of surgical procedures,7 and the optimal availability of the existing bone mass for providing stability to the implant. Moreover, at a microscopic level, it is believed that postextraction osteogenic activity may improve the boneimplant contact when treated implants are used.1,12 Another study, which examined the changes of the hard tissue immediately after implant placement, partially supported the fact that bone defects around the immediate implant could heal. The authors pointed to the fact that although new bone was apparent at the clinical examination, the microscopic examination evidenced a layer of connective tissue. From this it is concluded that an osteointegration process takes place between the bone and the implant.13 In addition, the buccolingual positioning of the immediate implants should be carefully chosen, because, contrary to previous knowledge, the protocol of immediate implants does not prevent the buccolingual resorption of the vestibular bone plate.14 Another drawback of this technique is that a fair amount of bone is necessary, since grafting and augmentation of large amounts of hard and soft tissues are not possible. If the hard and soft tissues are affected by various conditions,8 this technique is not recommended. Certain studies on immediate implant insertion have shown that bone remodeling, bone apposition, and healing also take place in the implant neck area. This is thought to be the reason why no other factors occur to influence the final esthetic result.5 The conclusions of a clinical study performed over 1 year – during which 35 immediate implants were inserted – confirmed that the protocol of immediate insertion may lead to good results regarding the peri-implant soft tissues and esthetic aspect.15 A recent analysis of the clinical results of immediate or early implant insertion concluded that immediate insertion may be successful regarding the implant survival rate. However, the esthetic result may be questionable as there is a high risk of esthetic failure, apart from wellselected cases. Therefore, the authors suggest that these protocols should be used by highly experienced implantologists.16 Immediate restoration could improve the soft tissue outcome.11 This conclusion is in accordance with our own experience; namely, that there is no ideal

synchronization between tooth removal and implant insertion, as every patient requires individual assessment. As a general rule, the immediate insertion protocol may be applied for the posterior segments, while late insertion should be preferred for the anterior segments.

Case 3: Immediate implant insertion with augmentation in the anterior zone

Fig 14-19 Tooth 11 is mobile and presents crown lengthening. The firm periodontal biotype, square teeth, flat periodontium, and apical contact points suggest a thick vestibular bone plate.

Fig 14-20 Retroalveolar radiograph does not evidence apical transparency. An implant will be inserted immediately after extraction.

Fig 14-21 3D image of the ideal implant position. The implant is placed in relation to the prosthetic abutment, so that the margins of the future crown are at the level of the enamel-cement junction of the adjacent teeth.

Fig 14-22 After removal of the fixation system, the implant position is obvious. It is placed palatally in order to leave space for the regeneration of the vestibular bone. The palatal position in immediate implantation takes into account the future resorption of the vestibular plate.

Fig 14-23 The alveolus is covered by graft material and then by collagen sponge. No flap is made in order to avoid scars.

Fig 14-24 The postextraction site is “sealed” by a bridge element connected with tooth 21.

Fig 14-25 Occlusal view of the implant position after osteointegration shows thick vestibular bone and mucosa.

Fig 14-26 Eight months later the temporary restoration is removed. The prosthetic pin is applied and the provisional crown adapts to the new situation.

Fig 14-27 Retroalveolar radiograph evidences the provisional bridge in situ, over the prosthetic pin, 6 months after application.

Fig 14-28 Prosthetic pin in situ.

Fig 14-29 Crown fitting and esthetic adjustment.

Fig 14-30 The soft tissue profile and the interproximal papilla could be preserved using an immediate implant and late prosthetic restoration.

Fig 14-31 Final radiograph after crown application.

Fig 14-32 Final appearance after the application of the definitive crowns on 11 and 21.

14.4 Delayed implant insertion After 6 to 8 weeks, spontaneous healing of the soft tissue above the extraction socket takes

place; this will allow a better primary closure for the bone graft.7 During this time, all the pathological conditions of the tissues in the socket of the extracted tooth improve and allow bone healing, thus optimizing implant osteointegration, as well as tissue integration in the case of bone augmentation and soft grafting procedures.17 As already mentioned, there is a study report based on a comparative analysis regarding the healing of the buccal margins around the implants 1 year after immediate insertion or at 4 to 6 weeks after insertion (early), following extraction and augmentation with membranes and bone grafts. Regarding the timing of single implants, the statistical results were good with early implantation protocols, due to the primary closure of the alveolus, which seems to facilitate the integration of the implant, bone, and barrier membranes.17 These results were confirmed by a similar study carried out to compare immediate and late implant insertion. However, the authors did not find significant differences between the groups regarding the size of the interproximal papillae.18

Case 4: Late implant insertion with augmentation in the anterior zone

Fig 14-33 Eight weeks after tooth removal, a concavity may be noticed at the level of the vestibular contour. The vertical dimension of the soft tissue does not present major alterations. The patient wears a Maryland bridge.

Fig 14-34 After removing the temporary bridge, a rectangular flap is realized in order to prevent postoperative scars. It also provides good visibility for the implant placement and the guided bone regeneration.

Fig 14-35 Mucoperiosteal detachment evidences the absence of the vestibular plate.

Fig 14-36 The alveolus is curetted before implant insertion.

Fig 14-37 The primary implant stability is obtained above the postextraction alveolus. The implant is chosen at least 4 mm longer than the postextraction alveolus.

Fig 14-38 An implant of 4.6 mm diameter and 12 mm length is selected. It is placed 2 mm apically in relation to the enamel-cement junction of the adjacent teeth in order to allow an esthetic emergence profile.

Fig 14-39 The autologous bone is placed on the implant surface in order to allow osteointegration (in this case harvested from the nasal spine with the piezosurgery device).

Fig 14-40 The second layer is composed of the slow-resorption xenograft. It will outline the alveolar ridge in the initial phase and maintain the contour in time.

Fig 14-41 A collagen membrane covers the graft in order to allow the substitution material to act like a matrix for the regeneration of the bone.

Fig 14-42 The vertical incisions are fixed by simple sutures, and the horizontal incision by mattress stitches.

Fig 14-43 Six months after implantation and guided bone regeneration, healthy soft tissue may be evidenced. The height of the interdental papillae is preserved.

Fig 14-44 The vestibular view of the prosthetic abutment in situ after removal of the temporary crown. The symmetry of the soft tissue is evidenced, in comparison with the neighboring tooth.

Fig 14-45 The final crown in place is esthetically well integrated.

14.5 The staged insertion of implants Compared to the immediate insertion of the implant, this technique may be more difficult in terms of the esthetic restoration because of the alveolar bone resorption, which may lead to a narrow ridge, buccal concavity, and loss of the gingival architecture. In such cases, as has already been mentioned, the implantologist should decide whether to perform hard and soft tissue regeneration procedures based on the radiographs, the diagnosis, and prosthetic treatment, in order to regenerate the lost tissue and obtain a satisfactory esthetic result. Therefore, among the drawbacks of this method are the longer duration of the treatment, and the increased number of surgical interventions. It is mandatory that implantologists should evaluate each case individually and take into account the response to surgical injury and the timing, in order to obtain an acceptable result.

Based on the initial situation of the architecture of the hard and soft tissues before the implant insertion, implantologists should first decide whether augmentation of tissues is necessary and, if yes, what the most suitable technique would be. Based on the data in the literature and on our experience, autogenic bone grafts represent a viable option for bone augmentation when the bone mass is insufficient, and the use of bone blocks harvested from the area of the mandibular symphysis or the mandibular branch when a large amount of grafting material is required. However, guided bone regeneration (GBR) is increasingly being used to regenerate the lost bone. Regarding the timing of the implant insertion, our protocol follows the guidelines, with decisions being made for each individual case separately. 14.6 Use of flaps in implant insertion At the time of implant insertion it is generally accepted that the larger the flap, the better the visibility of the operative field, with optimal visibility being crucial for correct implant placement. As the tendencies in current dentistry are in favor of minimally invasive therapies, large flaps are considered risky,19 especially in patients with a thin periodontal biotype. Studies have demonstrated that gum morphology is essential for the esthetic outcome of implant surgery,20 root-coverage procedures,19–21 and periodontal treatment.20,27 A thicker tissue is important to ensure successful results for implant restorations and root-coverage procedures.19 An alternative solution is to design a viable flap, such as the “aesthetic buccal flap” (ABF), and carefully plan tissue adaptation for tension-free primary closure. The ABF design was developed to protect the soft tissue of the gingival margin and to maintain an esthetic aspect.9 Nevertheless, its application depends on specific conditions, including the absence of soft tissue atrophy, and the amount of resorption of the interproximal bone.19 Most flap designs have their own criteria that determine their use. A prerequisite of the surgical decision is dependent on the hard and soft tissue condition, the gingival and periodontal biotype for the planning and assessment of incisions,22–24 as well as the appraisal of the surgical outcome. When the utility of various flap models is considered, the individual gingival characteristics of each patient will prompt the surgical technique and type of suture to be used, as well as other elements, such as whether augmentation is necessary. Many of the procedures performed in the oral cavity are classified as oral surgery, which also includes dental extraction, maxillary corrective surgery, oral pathology, facial trauma, and the correction of

temporomandibular joint disorders. Nowadays, dental implant treatments are often performed by the general dentist. However, implant insertion is a sensitive, specialized procedure that requires surgical skills, as well as knowledge about occlusion and the biological changes involved in the process. While certain surgical techniques belonging to oral surgery and periodontology were found adequate for implantology, others had to be changed and adapted in order to fulfill requirements in the implant dentistry field. The biotype of each patient will also influence the outcome of the procedure. For example, dental extraction in patients with a thin biotype may trigger unexpected anatomical alterations, while in patients with a thick biotype such changes may be minor or absent. Consequently, the implantation procedures should be adapted to the patient’s individual characteristics. Tissue quality differs among patients. Before making a flap, the patient’s biotype, as well as the quantity and quality of available tissues should be assessed. A thick biotype reacts to injury, surgical operations and other trauma by forming pockets, and maintains the soft tissue frame. On the other hand, a thin biotype reacts to injury and trauma by soft tissue atrophy.20 The identification of the patient’s biotype is a prerequisite of implant surgery that assesses the tissue response to this special operation. Surgery will be adjusted according to the biotype identified because of the differing tissue responses. The flap design used in the case of a thick biotype may not be suitable for a thin biotype. In 1969, Ochsenbein and Ross established that gingival morphologies could be classified into thick and thin.25 These were later labeled “periodontal biotypes” by Seibert and Lindhe.20,26,29 These biotypes have been mentioned in the results of implant operations and periodontal procedures.20 Thick tissue biotypes have proved to be more successful than thin tissue biotypes in terms of surgical outcomes, which is an important factor to be taken into consideration in any intervention for implant insertion.30 Though there is a tendency to use the same flap design for every indication, in reality the flap design needs to be adapted according to the periodontal type of each patient. During the grafting procedure, the tissue is manipulated in order to cover bone augmentation. The extension of the thick biotype over the augmentation is possible; if it is tension-free, healing will take place without complications. The extension of the thin biotype may cause tissue tears and necrosis.21 Moreover, in the same way that a wrong incision may cause scars, a manipulated thin biotype may prevent adequate nutrient supply and revascularization, leading to necrosis. Therefore, incisions in very thin tissue should be avoided, and a flap design that

preserves the biotype should be considered.25 When grafting procedures are used in implantology, after surgery it is necessary to suture the flap without tension.29 This is problematic in the case of large augmentations. As a bone graft implies adding autogenous bone or bone-grafting materials, the presence of the additional volume makes soft tissue manipulation difficult. The primary flap closure requires pulling the tissue over the graft, which makes tension-free sutures challenging.12 Moreover, the extension of tissue in the esthetic zone will cause alterations in the soft tissue position and quality. The approach should take into account the preservation of the tissue during closure. If the facial flap is pulled over the flap opening, the vestibular tissue will be pulled crownward, which will result in a thinned biotype and insufficient volume of attached tissue.28 At the same time, if the tissue is extended too much in patients with a thick biotype, it will thin out and become prone to tears or other injuries.12 14.7 Conclusions Modern dentistry attempts to minimize the trauma for the patient and the masticatory system. When dealing with the anterior zone, the esthetic aspect is essential. The fact that different tissues heal differently and react differently to trauma has prompted the creation of several flap models in order to offer patients a minimally invasive implant therapy and the best solution from the point of view of function and esthetics. The esthetic and functional success of the flap approach and implant insertion depend on the tissue type and the surgical wound. A conservative flap design and efficient suture minimize tissue trauma and optimize the healing rate.12 Before any surgical intervention, it is necessary to perform a critical diagnosis of the patient’s hard and soft tissues. The treatment will be established based on the condition and quality of each patient’s tissue, in correlation with the gingival morphology.26,28

REFERENCES 1. Grunder U, Gracis S, Capelli M. Influence of the 3-D bone-to-implant relationship on esthetics. Int J Periodontics Restorative Dent 2005;25:113–119. 2. Spray JR, Black CG, Morris HF, Ochi S. The influence of bone thickness on facial marginal bone response: Stage 1 placement through stage 2 uncovering. Ann Periodontol 2000;5:119–128. 3. Ridge alterations following tooth extraction with and without flap elevation: An experimental study in the dog. Clin Oral Implants Res 2009;20:545–549. 4. Araújo MG, Sukekava F, Wennström JL, Lindhe J. Ridge alterations following implant placement in fresh extraction sockets: An experimental study in the dog. J Clin Periodontol 2005;32:645–652. 5. Nevins M, Camelo M, De Paoli S, et al. A study of the fate of the buccal wall of extraction sockets of teeth with prominent roots. Int J Periodontics Restorative Dent 2006;26:19–29. 6. Barone A, Ricci M, Tonelli P, Santini S, Covani U. Tissue changes of extraction sockets in humans: A comparison of spontaneous healing vs. ridge preservation with secondary soft tissue healing. Clin Oral Implants Res 2012 Jul 12. doi:10.1111/j.1600-0501.2012.02535. 7. Buser D, Chappuis V, Bornstein MM, Wittneben JG, Frei M, Belser UC. Long-term stability of contour augmentation with early implant placement following single tooth extraction in the esthetic zone. A prospective, cross-sectional study in 41 patients with a 5- to 9-year follow-up. J Periodontol 2013;84:1517–1527. 8. Lau SL, Chow J, Li W, Chow LK. Classification of maxillary central incisors: Implications for immediate implant in the esthetic zone. J Oral Maxillofac Surg 2011;69:142–153. 9. Sclar AG. Preserving alveolar ridge anatomy following tooth removal in conjunction with immediate implant placement. The Bio-Col technique. Atlas Oral Maxillofac Surg Clin North Am 1999;7:39–59. 10. Jivraj S, Chee W. Treatment planning of implants in the aesthetic zone. Br Dent J 2006;201(2):77–89. 11. De Rouck T, Collys K, Cosyn J. Single-tooth replacement in the anterior maxilla by means of immediate implantation and provisionalization: A review. Int J Oral Maxillofac Implants 2008;23(5):897–904. 12. Botticelli D, Berglundh T, Lindhe J. Hard-tissue alterations following immediate implant placement in extraction sites. J Clin Periodontol 2004;31:820–828. 13. Covani U, Bortolaia C, Barone A, Sbordone L. Bucco-lingual crestal bone changes after immediate and delayed implant placement. J Periodontol 2004;75:1605–1612. 14. Covani U, Cornelini R, Barone A. Vertical crestal bone changes around implants placed into fresh extraction sockets. J Periodontol 2007;78:810–815. 15. Kan JYK, Rungcharassaeng K, Lozada J. Immediate placement and provisionalization of maxillary anterior single implants: 1-Year prospective study. Int J Oral Maxillofac Implants 2003;18:31–39. 16. Schropp L, Isidor F. Timing of implant placement relative to tooth extraction. J Oral Rehabil 2008;35:33–43. 17. Schropp L, Isidor F, Kostopoulos L, Wenzel A. Interproximal papilla levels following early versus delayed placement of single-tooth implants: A controlled clinical trial. Int J Oral Maxillofac Implants 2005;20:753–761. 18. Steigmann M. Aesthetic buccal flap design for correction of buccal fenestration defects. Pract Proced Aesthet Dent 2008;20:487–493 19. Fu JH, Yeh CY, Chan HL, Tatarakis N, Leong DJ, Wang HL. Tissue biotype and its relation to the underlying bone morphology. J Periodontol 2010;81:569–574.

20. Zigdon H, Machtei EE. The dimensions of keratinized mucosa around implants affect clinical and immunological parameters. Clin Oral Implants Res 2008;19:387–392. 21. De Rouck T, Eghbali R, Collys K, De Bruyn H, Cosyn J. The gingival biotype revisited: Transparency of the periodontal probe through the gingival margin as a method to discriminate thin from thick gingiva. J Clin Periodontol 2009;36:428–433. 22. Huang LH, Neiva RE, Wang HL. Factors affecting the outcomes of coronally advanced flap root coverage procedure. J Periodontol 2005;76:1729–1734. 23. Hwang D, Wang HL. Flap thickness as a predictor of root coverage: A systematic review. J Periodontol 2006;77:1625–1634. 24. Claffey N, Shanley D. Relationship of gingival thickness and bleeding to loss of probing attachment in shallow sites following nonsurgical periodontal therapy. J Clin Periodontol 1986;13:654–657. 25. Ochsenbein C, Ross S. A reevaluation of osseous surgery. Dent Clin North Am 1969;13:87–102. 26. Seibert JL, Lindhe J. Esthetics and periodontal therapy. In: Lindhe J (ed). Textbook of Clinical Periodontology, ed 2. Copenhagen: Munksgaard, 1989:477–514. 27. Lee A, Fu JH, Wang HL. Soft tissue biotype affects implant success. Implant Dent 2011;20:e38–47. 28. Kao RT, Fagan MC, Conte GJ. Thick vs. thin gingival biotypes: A key determinant in treatment planning for dental implants. J Calif Dent Assoc 2008;36:193–198. 29. Velvart P. Soft tissue management. J Endodon 2005;31:4–16. 30. Elian N, Cho S-C, Froum S, Smith RB, Tarnow DP. A simplified socket classification and repair technique. Pract Proced Aesthet Dent 2007;19:99–104.

ANDREI IACOB

Chapter XV ESTHETIC STRATEGIES IN ORTHODONTICS

15.1 CURRENT ESTHETIC CONSIDERATIONS IN ORTHODONTICS

Fig 15-1 Ricketts – “E-line”.

Fig 15-2 Steiner – “S-line”.

Fig 15-3 Holdaway – “H-line”.

15.1.1 Introduction Orthodontic treatments aim at improving the patient’s quality of life. The design, implementation, and completion of the therapeutic plan should take into account the fulfillment of the following goals:1 • Improvement of facial esthetics. • Improvement of dental esthetics. • Achievement of a functional occlusion. • Improvement or maintenance of periodontal health. • Stability of the results. • Improvement or maintenance of the quality of “airways”. One of the main objectives of orthodontic treatment has always been an ideal dentition. Increasing consideration has recently been given to facial esthetics and the ways orthodontic treatment should be designed in order to obtain the desired esthetic effects. The emphasis on the dental and skeletal components remains important, but increasing attention is paid to the soft tissues. In order to obtain a natural and harmonious appearance, the patient should be considered as a whole. The characteristic features of the tooth or dental segments represent only a part of a person and they cannot be considered separately.

Esthetics in orthodontics may be analyzed from the following points of view:2 • Facial esthetics. • Dental esthetics including: – microesthetics – the elements that make a tooth look like a tooth; – macroesthetics – the principles that apply when groups of teeth are considered. • Gingival esthetics. 15.1.2 Facial esthetics The ability to recognize a beautiful face is inborn in human nature. Given the subjectivity in any judgment of facial esthetics, it is very difficult to establish general standards for its assessment. Many authors have set a series of reference points and esthetic analyses, first starting from the bone structures, and more recently with an emphasis on the soft tissues: Ricketts – “E-line” (tip of the nose to soft tissue pogonion) (Fig 15-1);3 Steiner – “S-line” (soft tissue pogonion to a point situated on the center of the curve between the nose tip and subnasale) (Fig 15-2);4 Holdaway – “H-line” (upper lip to soft tissue pogonion) (Fig 15-3);5 Burstone – “B-line” (subnasale to soft tissue pogonion) (Fig 15-4);6 Sushner – “S’-line” (soft tissue nasion to soft tissue pogonion) (Fig 15-5);7 Arnett – “soft tissue cephalometric analysis”.8,9 In order to evaluate the face, the patient should be examined both from the front and in profile, with the head in a “natural head position” and the lips relaxed. The clinical examination should include the position of centric occlusion (CO) as well as centric relation (CR), with the mouth closed to the first tooth contact. In this way, any facial alterations can be noticed that occur due to the deviation of the mandible from the CR to the CO.10 Facial esthetics analysis from the frontal view provides information on the form of the face, the symmetry, the relations between the median lines of the various structures, and the relations in the vertical plane between the face heights (Fig 15-6).10 The general form of the face may be described as round or oval, wide or narrow, short or long. Several anthropometric reference points may also be measured, such as the bizygomatic width that represents the widest facial dimension, or the bigoniac width, which should be about 30% smaller than the bizygomatic width.10 Median lines should be analyzed with the mandibular condyles centered in the glenoid fossae and at the first tooth-contact position. Without these relations, the analysis of the median lines and their relations cannot be assessed correctly. According to Arnett,10 the midline of the

face should be taken to be the line that passes through the points marking the center of the upper lip filtrum and the center of the nose bridge and a point situated at the mid-distance between the inner corner of the eyes (Fig 15-6).

Fig 15-4 Burstone – “B-line”.

Fig 15-5 Sushner – “S’-line”.

An esthetically attractive face is divided into three equal heights by horizontal lines going

through the brows line, subnasale, and soft tissue menton. Deviations from these norms will be represented by the increase or the decrease of one or more heights (Fig 15-6).10 Studies have shown that in reality the face heights are rarely equal, and for facial esthetics it is more important to have a vertically good relation between the elements composing the lower part of the face. The lower height is placed between the subnasale and soft tissue menton anthropometric points. This level includes three components: the upper lip, the interlabial gap, and the lower lip. The lips should be assessed separately, in rest position. The length of the upper lip, measured between the subnasale and stomion anthropometric points, is 19 to 22 mm, with higher values in men and in the elderly. The space between the relaxed lips is 1 to 5 mm. Statistically, larger spaces have been recorded in women as compared to men. The lower lip is measured between the lower stomion and soft tissue menton anthropometric points, ranging from 42 to 48 mm and increasing with age, probably due to the accumulation of adipose tissue in the submental area. The normal ratio between the upper and lower lip dimensions is 1:2.2. Well-proportioned lips are in harmony regardless of their length.10

Fig 15-6 The clinical facial examination – frontal view.

Fig 15-7 The clinical facial examination – profile view.

In addition to the data provided by the relaxed lip position, the facial aspect is also analyzed in closed-lip position. This position may evidence possible dimensional imbalance between the skeletal and the soft tissue structures. If the soft and bony structures are well balanced, the lips may close from the rest position without tension in the mentalis, alar, or the orbicular muscles. The size of the lips is an important factor in facial esthetics. The red of the upper lip has values between 6 to 9 mm, and that of the lower lip between 8 to 12 mm. A correct ratio between the lips is when the red of the upper lip is 2 to 3 mm smaller than the lower one.10 The patient’s profile is clinically assessed with the patient seated in “the natural head position“, the mandible centered in CR, the lips at rest, and the mouth closed to the first tooth contact. If necessary, and in order to obtain this position, occlusion waxes will be used.10 According to Arnett, in the profile analysis (Fig 15-7) the face may be divided into three components: the mandibular area, the maxillary area, and the high midface.10 In the high midface, four soft tissue elements are analyzed: the soft tissue glabella, the soft tissue orbital rim, the soft tissue cheekbone, and the subpupil area (Fig 15-7). The maxillary area includes four soft tissue elements: nasal base, position of the upper lip, the supporting tissues of the upper lip, and the nasal projection (Fig 15-7). The mandibular area includes the position and prominence of the lower lip, the soft tissue

pogonion projection, the length and contour of the throat, and the relation in sagittal plane between the maxillary and mandibular incisors: the overjet. In this area, the profile projection, the projection of the chin, and the amount of adipose tissue in the submental zone should be analyzed (Fig 15-7). According to Arnett, the analysis of the overjet is part of the examination of the mandibular profile, the normal value being between 0 and 3 mm. The analysis of the overjet will be repeated in the intraoral examination, and will be also analyzed using cephalometrics.10 15.1.3 Dental esthetics When speaking of dental esthetics, the whole dentofacial complex is envisaged from the points of view of the shape, structure, color, function, and tooth exposure. The dynamic relation between the teeth and the surrounding soft tissues, during and after orthodontic treatment, as well as the facial features of the patient are very important and must be analyzed. The amount and shape of the dental crown that will be exposed during the lip movements should agree with the age, gender, and facial traits of the patient. The purpose of the analysis is to obtain some guidelines on the assessment of the esthetic characteristics and the adequate dimension, vertical and transverse, of both static and dynamic tooth display.2 Based on the principles of visual perception and their clinical application in dentofacial esthetics, it has been evidenced that an accurate analysis of dental esthetics requires the examination of the patient’s facial expression from the front, at rest and during function.12 Information such as the alignment of midlines, or the right-left symmetry of canines and premolars, can only be obtained if the patient is observed from the frontal view.2,12 From this perspective, the orthodontist should analyze the following parameters:2,13 • Length of the maxillary and mandibular incisors’ crowns. • Contour of the incisal margins before and after the recontouring of these incisal margins. • Position and symmetry of the gingival margins of the maxillary and mandibular anterior teeth. • Axial inclinations of all anterior teeth. • Midlines. • Contact areas between teeth (the place where teeth touch). • The symmetry and torque of canines and premolars (labiolingual inclination of these teeth).

• The harmonious curved display of the teeth, from the anterior to the posterior teeth. If the patient’s examination is performed with the esthetic objectives in mind, especially in the context of the multidisciplinary approach, it should start with the analysis of the position of the maxillary incisors in relation to the upper and lower lips. The assessment should be performed with the lips at rest and during smile.8,9,10,14 The most valuable esthetic information in treatment planning is obtained by observing the patient during a normal conversation. The visibility of the teeth during smile also provides valuable information, as the upper lip is raised. With age, the soft tissues lose their tone and elasticity, the upper lip drops and covers more of the maxillary incisor, while the lower lip descends and uncovers more of the mandibular incisor.2,15,16 In this context, the position of the maxillary incisors may be considered acceptable or unacceptable (Figs 15-8 and 15-9). An acceptable level of exposure of the maxillary incisors at rest depends on the patient’s age. Studies show that the more advanced the age, the less the maxillary incisors will be exposed by the upper lip. This is one of the reasons a gummy smile is more frequently seen in young people. Thus, if at the age of 30 the level of exposure of the incisors is 3 to 4 mm, it may decrease to only 1 mm at the age of 60. The decrease may be caused by the poor muscular tone of the upper lip.2,14,17,18 Various other studies have reported age-induced alterations to the lips. In a study by Peck et al,19 the exposure of maxillary incisors with the upper lip at rest is 4.7 mm in boys and 5.3 mm in girls at the age of 15 years. Another representative study by Vig and Brundo18 demonstrated that the decrease of the maxillary incisor exposure is accompanied by increased mandibular incisor exposure with age.

Fig 15-8 Insufficient exposure of the maxillary incisors.

Fig 15-9 Overexposure of the maxillary incisors.

If the exposure of the maxillary incisors is considered inadequate, the main objective of a multidisciplinary treatment would be to correct this by restorative methods, dental prosthetics, orthodontic extrusion, or intrusion and orthognathic surgery.14,20 In orthodontics and dentofacial orthopedics, the current therapeutic tendencies for overbite have changed as a result of the importance attributed to the exposure of the maxillary incisors,

both at rest and during function.2,20,21 In the past, the emphasis was on the mandatory opening of the bite by the intrusion of the incisors and/or the extrusion of the molars. Nowadays, the exposure of a small area of the gingival margin during smile (up to 2 mm) is acceptable, as long as the visibility of the incisors at rest is adequate, and the resulting overbite and overjet at the end of the treatment ensure a correct functional occlusion.2,22,23 The various methods of intrusion used in orthodontics, such as special intrusion arches, overlay arches, etc, may determine an exaggerated intrusion, the maxillary incisors being completely covered by the upper lip at rest at the finish of orthodontic treatment, a condition aggravated by age.2,23 The relation between the position of the incisors and the lip must be constantly monitored during the orthodontic treatment. During this monitoring period, it should be decided whether orthodontic intrusion is necessary or not, or whether a mixed therapy is necessary, consisting of incisor intrusion and crown lengthening by restorative methods (direct restoration) or by prosthetics (indirect restoration).2,22,23 Usually, overbite is due to a marked curve of Spee, in which the six anterior mandibular teeth are above the functional occlusion plane. In these cases, the correct therapeutic solution is the intrusion of the mandibular teeth by intrusion arches.2,22 An alternative to the incisors’ intrusion for overbite in children may be the extrusion of the molars. This effect may be obtained with various orthodontic appliances: functional appliances, bite plates that ensure the disocclusion of the molar zone, and extraoral appliances such as facebows.2,24 It is important to bear in mind that molar extrusion should be limited to children with a vertical, or preferably counterclockwise, facial pattern, and avoided in those with a clockwise pattern. Molar extrusion is not indicated in adults because of the lack of stability, as well as the high patient compliance requirements and esthetic impairment, both representing difficulties for this age group.2,25,26 The upper dental midline is assessed in relation to the upper lip filtrum, the middle of which is one of the most symmetrical points for soft tissues. Most patients use this point as a reference in appreciating the upper interincisor line at the end of orthodontic or orthosurgical treatment (Fig 15-10).10 The coincidence, or its absence, between the upper and lower interincisor lines is another factor to be analyzed in dental and facial esthetics (Figs 15-11 and 15-12). In some cases, there is no coincidence between these lines due to various causes: skeletal asymmetries,

discrepancies in size between inter-/intradental arches, edentulous spaces altering the arch symmetry, morphologically or dimensionally inadequate dental restorations. The impact of this discrepancy on dental esthetics is actually less than it was initially thought (Figs 15-13 and 15-14). Some studies27,28 analyzed the perception of the deviation of the interincisor line in three observer groups composed of orthodontists, general dental practitioners, and persons without dental training. The results showed that neither general dentists nor those without dental training noticed any difference up to a deviation of 4 mm, as long as the long axis of the teeth was parallel with the vertical axis of the face. Both orthodontists and the two other groups considered that a deviation up to 4 mm of the interincisor lines does not impact on facial esthetics. An important effect in dental esthetics is the parallelism of the long axis of the maxillary incisors (Fig 15-15). Research has demonstrated that a 2 mm inclination of the long axis of these teeth is considered unpleasant.14,27,29 The correction of the axis may be performed by orthodontic or prosthetic methods, according to the restoration required for these teeth. The same considerations regarding the position, symmetry, slant, and exposure of the incisors should be given to the mandibular teeth. The mandibular incisors should be related to the position of the maxillary ones to ensure optimal functional and esthetic interactions between them. The exposure and positioning of the mandibular incisors will be included in the treatment plan and performed by orthodontics, restorative procedures, prosthetics, implants, or orthognathic surgery.14,30,31 The orthodontist should be aware of the fact that dental esthetics and the functional occlusion are in a mutual relationship. The two concepts, esthetics and function, cannot exist without one another. The most successful, natural-looking dental esthetics is the result of the integration of the existing relations between the morphological and functional details.32

Fig 15-10 Upper midline correctly centered in relation to the upper lip at the end of the orthodontic treatment.

Fig 15-11 Midline deviation before the orthodontic treatment.

Fig 15-12 Centered midlines in the same patient at the end of the orthodontic treatment.

Fig 15-13 Correctly centered midlines at the end of the orthodontic treatment.

Fig 15-14 Midline discrepancy at the end of the orthodontic treatment.

Fig 15-15 Lack of parallelism shows a discrepancy between the tooth axes and the facial midline.

Fig 15-16 Uneven free gingival margins and gingival recessions.

In this context, we should bear in mind that after establishing the ideal position of the incisal margins, the orthodontist should position the level of the posterior occlusal plane in relation to this position. The correction of the posterior occlusal plane may be performed by orthodontics, prosthetics, or orthognathic surgery. The size and morphology of the crowns, their modifications by wear or different types of restorations, the patient’s facial pattern, the amount and position of the alveolar bone, and the relation established by the posterior teeth with the lower lip during smile are all factors that will influence the choice of the therapeutic modalities for setting the level of the occlusion plane in the posterior area, as indicated by each clinical case.14,33,34 15.1.4 Gingival esthetics Problems with gingival esthetics may be due to the exaggerated or uneven exposure of the free gingival margins, and also to local or general gingival recessions that occur following bone tissue loss.35 The level of the free gingival margins is determined by the axial cant and the alignment of the teeth (Fig 15-16). The correct positioning of the teeth on the dentoalveolar arch will level the gingival margins and improve gingival topography (Figs 15-17 and 15-18).11 A difficult instance from the point of view of dentogingival esthetics is encountered in cases of maxillary lateral incisor anodontia, when the space is closed by the substitution of the lateral incisor by the canine. The leveling of the gingival margins is necessary in these cases in order to obtain the best gingival esthetics and avoid the unesthetic appearance of the canine protuberance in the substitution area (Fig 15-19).35,36 The dentogingival esthetic objectives to be taken into consideration are:

• The contours of the gingival margins of the maxillary central incisor and maxillary canine should be above the contours of the maxillary lateral incisor.36,37

Fig 15-17 Uneven free gingival margins before the orthodontic treatment.

Fig 15-18 Leveling of the free gingival margins by orthodontic treatment in the same patient.

Fig 15-19 Clinical view of lateral incisor anodontia.

Fig 15-20 Individualized bonding of the brackets in lateral incisor anodontia: mandibular premolar brackets, for torque correction, may be seen bonded on the maxillary canines that will substitute the lateral incisors.

• The long axes of the crowns of the maxillary central incisors and canines should be situated mesial to the gingival zenith.36,37 • The long axis of the maxillary lateral incisor crown should pass through the gingival zenith.36,37 • The proportions of tooth sizes: the tooth width should be about 60% to 70% of its length.36,38 The therapeutic strategies should include the individualization of the bonding of the brackets on the teeth in order to make it possible (Fig 15-20):36 • The slight extrusion and tipping of the long crown axis of the maxillary canine replacing the lateral incisor in relation to the gingival zenith. • The application of a positive torque on the maxillary canine replacing the lateral incisor in order to improve the emergence profile and the protruding aspect of the canine fossa. • The intrusion of the first maxillary premolar in order to mimic the position of a maxillary canine in relation to the free gingival margin. • The adjustment of the dental proportions according to the requirements, by restorative or prosthetic methods, in agreement with the general dentist. It is important that orthodontic treatment maintains and provides an aligned and esthetic gingival contour. Therefore, we must take into consideration the fact that when patients have one or several teeth with fractured, chipped, or worn out crowns, the lengthening of the clinical crown by orthodontic extrusion may determine an unpleasant aspect as a result of the altered gingival contour. In such cases, the correct therapeutic management consists of the direct or

indirect restoration of the affected teeth, after the orthodontic leveling of the gingival contour.35 If the orthodontic treatment of teenagers should take into account the alignment of the marginal crests and cusps, in adults the correct leveling of the gingival contour should be ensured, ie, the leveling of the interproximal alveolar bony crests along the dentoalveolar arch.11 Gingival esthetics may be greatly improved by the beneficial effects at the level of the bone and soft tissues, which are obtained by the dental movements during orthodontic treatment. Orthodontic treatment may lead to improved prognosis of periodontal disease and, in some cases, the minimization of the indication or extent of periodontal surgery.11 The application of brackets on the various teeth will be performed according to the individual in order to obtain the alignment of the alveolar crests and free gingival margins, without taking into account the bonding reference marks specific to various bracket systems. A change to the bonding height of the brackets on the teeth with respect to the free gingival margin will require an occlusal adjustment equilibration through selective grinding of these teeth during the stage of orthodontic alignment and leveling.11 These reductive coronoplasty procedures will also provide a better crown/root relation for the teeth affected by periodontal bone loss.39 Certain vertical periodontal defects may be minimized or eliminated by controlled dental extrusions using light forces (orthodontic eruption) that will stimulate bone formation without loss of gingival attachment in these teeth, thus improving the level of alveolar bone and contributing to the overall improvement of gingival esthetics.40 This type of slow orthodontic extrusion may be used in cases with important vertical periodontal defects of the maxillary anterior teeth, in which the marked bone resorption associated with gingival recessions and ample dental migration prevents an adequate esthetic restoration. In these situations, the bone level may be augmented by apposition of new alveolar bone, while the soft tissue position may be corrected by increasing the level of the attached keratinized gingiva by slow orthodontic extrusions (0.5 to 1 mm extrusion per month, followed by a month of rest). This technique includes the reduction of the crown length of the extruded tooth and, in some cases, even the endodontic treatment of the tooth. At the end of the procedure, clinical condition permitting, the tooth may be kept or replaced by an implant, this time in a favorable implant site.41–45 In the context of bone formation by orthodontic-forced eruption, before the orthodontic treatment is initiated, specific periodontal procedures should be performed to ensure

eradication of local infection and inflammation, and, if necessary, procedures of guided tissue regeneration should also be performed. Only in these conditions will the orthodontic-forced eruption take effect on bone regeneration, and result in an increase of the width of the attached keratinized gingiva, and even have an effect on the osteointegration of the materials used for tissue regeneration.46 The topography of the bone loss defect in relation to the direction of the orthodontic tooth movement plays an important role. The orthodontic movement of the tooth away from the bone loss defect may have positive effects on bone regeneration due to traction forces applied in the bone loss defect area, while the orthodontic movement of the tooth toward the bone loss defect may, at best, determine the maintenance of alveolar bone level, or even a worsening of the periodontal defect due to pressure forces applied in the area of the bone loss defect.46 An important component of gingival esthetics is ensured by the presence, size, and position of the interdental papillae. The normal dimension of the gingival tissues above the proximal alveolar bone ridge is 4.5 mm. Studies have shown that the optimal ratio between the size of the papillae and the crown length of the maxillary central incisors is 1:2.47,48 An important gingival esthetics problem is represented by the orthodontic alignment of teeth in the presence of periodontal defects and gingival recessions, which will lead to the appearance of the so-called “black triangles” in the proximal spaces. This creates an unesthetic appearance, especially in the maxillary anterior area. One way to solve this esthetic problem is to remove a small amount of interproximal enamel in order to facilitate tooth contact. Another approach moves the teeth contact points towards the cervical, thus diminishing the spaces for the interproximal papillae. This approach is more efficient in the case of trapezoidal incisors, which allow more interproximal reduction.34,48 15.1.5 Smile esthetics The relationship between gingival, dental, and facial esthetics is best understood in the esthetic analysis of the smile. An accomplished smile esthetic is obtained when the anterior teeth are in harmony with the guidelines of occlusion and stability. It should be taken into account that the position of the incisal margins determines the angle of the anterior guidance and that good positioning of the incisors affects both dental and facial esthetics, as well as the occlusal function and the case stability.32 The smile line is defined as the relation between the inner contour of the lower lip and the incisal margins of the maxillary incisors. It may be of three types: parallel, straight, or

reversed. Studies have reported that 85% of the population have the incisal margins parallel with the lower lip, in 14% the incisal margins are straight, and only in 1% are the incisal margins reversed. To sum up, the objective of esthetic rehabilitation is to achieve a contour of the incisal margins that is parallel with the lower lip. A reversed contour is often associated with marked wear of the maxillary incisors. There is also a gender dysmorphism, the smile line in men being lower than in women.2,18,49 The types of smile may be analyzed from the point of view of the amount of exposure of the incisors and the gingival margins. The coverage of the incisors by the upper lip classifies the smile into several types: smiles with little exposure, average exposure, and large exposure of the maxillary incisors.2 The most frequent smile type is an average exposure of the maxillary incisors (about 70% of young adults), in which 75% to 100% of the upper incisors’ surface is exposed. In 20% of the population, the exposure is less than 75% of the incisors’ surface, while the smile that exposes the whole surface plus a small portion of the gingiva, ie, the gummy smile, is seen in 10% of the population. The number of teeth exposed in the smile is another factor in smile and dentofacial esthetics. In young adults, the smile reveals the six anterior teeth and the first or second premolar; only in 4% of cases does the smile reveal the first molar.49 The gummy smile is defined as the exposure of 2 mm or more of the gingival margin when smiling. The issue of gingival exposure during the smile has been a subject of huge debate between orthodontists for a long time. The etiology of the gummy smile may be considered the result of the combined effects of an anterior vertical maxillary excess and the increased muscular capacity to raise the upper lip during smile, as well a number of other factors, such as a greater mouth opening at rest, and excessive overbite and overjet.2,50 Surprisingly, the length of the upper lip, or the length of the central incisor, and the angles of the mandibular and palatal planes are not related to the etiology of the gummy smile.51 The treatment of patients with a gummy smile usually includes combined orthodontics, periodontics, and surgical methods. The differential diagnosis should consider the visibility of the incisors at rest and of the gingival margins when smiling. If at rest the exposure of the incisors is good, their intrusion is not necessary, but the lengthening of their crowns by the means of gingivoalveoloplasty is indicated in order to reduce the visible gum.52,53 When the alveolar ridge is reduced for surgical lengthening of the clinical crown, the gingival margins will stabilize at about 3 mm from the new alveolar bone level within six months.54

More drastic therapy of the gummy smile may require orthognathic surgery that repositions the maxillary jaw (Le Fort I osteotomy) and the reduction of the excessive maxillary height.51 The pleasant appearance of the smile depends very much on the incisor crown torque. This is due to the way light is reflected on the buccal surface of the tooth. In people with correct crown-root torque and interincisal angle, the smile is more pleasant than in people with a wide interincisal angle and with incisors with a negative crown torque.2 A number of studies analyzing the transversal dimension of the smile have evidenced that the fullness of a smile depends on the correct torque of the maxillary canines and premolars, as well as their shape within the different facial types, rather than on non-extraction therapies or arch expansion, leading to an exaggerated dental tipping.2 The most important elements on which the transversal dimension of the smile depends are:2 • Labiolingual crown inclination of the terminal tooth in each quadrant that shows when smiling. • Symmetry of the crown inclination of the contralateral teeth. • Harmony of the front-to-back tooth display curve. • Relation between the size of the maxillary apical base and the labiolingual crown torque of the maxillary teeth. • Presence or absence of buccal corridors. Numerous studies that have been done have reported on the perception of buccal corridors,2,55–58 and none have evidenced a relationship between them and smile esthetics. The presence of these negative spaces is considered to be a feature that makes the smile more natural. Apparently, the labiolingual crown torque of the canines and premolars is equally or more important than the dark areas of the buccal corridors for the fullness of the smile. If, at the beginning of the orthodontic therapy, there is a dark space between the mouth corners and the maxillary dental arch, but the maxillary dental arch is acceptable in shape and width, then we should consider deliberately torqueing the crowns in a buccal direction in order to minimize the dark space (Fig 15-21). The transversal expansion of the maxillary jaw is indicated only when it is considered too narrow in relation to the mandibular jaw.2 The maxillary teeth labiolingual crown torque varies greatly from one patient to another. There are patients with wide maxillary arches and teeth lingually inclined, as there are patients with narrow arches and teeth buccally inclined.2 Due to these characteristic features, the orthodontic treatment should be personalized for each patient for optimal esthetic results.

15.1.6 Extractions in orthodontics and esthetics Extraction versus nonextraction is probably the oldest and most wrenching debate in orthodontics. This debate began with Case and Angle, but it is still topical nowadays. The advocates of nonextraction therapy argue that extractions can induce facial decline, while keeping all the teeth in the arch will automatically produce an adaptation of the soft tissue and bone, which will lead to a more harmonious and esthetic appearance.59 Choosing an option of treatment with extraction or nonextraction should be the result of a thorough diagnosis that takes into account the treatment objectives of optimum dental and facial esthetics, functional occlusion, periodontal health, and stability.59 The orthodontist should analyze each clinical case to decide whether the esthetic and functional goals can be accomplished keeping all the teeth in the arch. If it is possible to do so, then extractions should not be considered. In many instances, however, extractions are necessary to improve the patient’s esthetic appearance and to achieve a solid, functional occlusion. Even if there is a common belief that extractions are detrimental to facial esthetics, the studies and the orthodontic literature do not support this belief. The following is said in an article by Bishara and Jakobsen: “The extraction/nonextraction decision, if based on sound diagnostic criteria, does not have a systematic detrimental effect on the facial profile.”60 In another article comparing the esthetic results of profiles of patients treated with both extraction and nonextraction therapy, Luppanapornlarp and Johnston came to the conclusion that premolar extractions do not cause “dished-in” profiles and that “it was the nonextraction patients who tended to have more concave faces, whereas the extraction patients more often had what nonextraction advocates might call a nice full pleasing profile”.61 Another misconception is that extractions could have a detrimental result regarding facial and dental esthetics by altering the arch width and the teeth exposure, and worsening the patient’s smile by creating large buccal corridors. Again, this idea it is not supported by the literature.2 In his chapter entitled Esthetics in Tooth Display and Smile Design, Zachrisson says:

Fig 15-21 Marked inward inclination of the dental axes, which make possible the reduction of the buccal corridors by inclining the teeth in buccal direction.

“Fullness of the smile should be sought through adjustment of the clinical crown torque of the maxillary canines and premolars to their most esthetic appearance in different face types, rather than through nonextraction heroics or unnecessary lateral expansion and labial tipping of the maxillary dentition.”2 There are many ways in which extractions can lead to an improvement of dentofacial esthetics. One of the most important advantages of extraction therapy is that it allows the clinician to properly position the maxillary and mandibular incisors in the context of the face. This is a very important concept and it needs to be understood that extraction does not necessarily mean retraction. Another important advantage is that extractions allow the orthodontist to perform vertical control mechanics. Without vertical control, there would be a great tendency for the mandible to rotate clockwise. With the help of extractions and minimum anchorage mechanics, the posterior teeth can be moved forward without extrusion in order to achieve counterclockwise rotation of the mandible. This type of mechanics rotates the mandible upwards and forwards, reduces the lower-third height, projects the chin forward, and reduces lip strain.59

15.2 ESTHETIC THERAPEUTIC OPTIONS IN ORTHODONTICS Orthodontic appliances have undergone several stages and changes in time. The increased referral rate of adults to orthodontic therapy, and the demand for such therapies in the current multidisciplinary context of dentistry, have led to the development of fixed and removable orthodontic appliances that have the expected outcome of not changing, or changing very little, the patient’s esthetic appearance during treatment. This technological progress has brought new methods of manufacturing orthodontic appliances, which in turn has led to the emergence of a number of orthodontic systems and the development of appliances that respond to the increasing esthetic demands from mainly adult patients today. There have also been changes in the case of metal brackets for esthetic purposes (Fig 1522). The size of brackets has been reduced in order to minimize the visual impact on the tooth surface, and some companies have covered the bracket surfaces with a zirconium nitride layer in order to confer an esthetic aspect, similar to gold.62 These new manufacturing technologies have also resulted in the availability of various ceramic and plastic types of brackets (Fig 15-23), as well as new lingual systems and orthodontic aligners. Among the types of esthetic orthodontic systems currently available, the most widely used are: • Plastic or ceramic esthetic orthodontic appliances. • Lingual orthodontic systems. • Orthodontic aligners. 15.2.1 Plastic or ceramic esthetic orthodontic appliances The optical properties of esthetic brackets, such as shade, transparency or translucency, and fluorescence reduce their perception on the teeth. Esthetic orthodontic brackets may be translucent or transparent. The former are made of plastic, or polycrystalline ceramic (aluminum oxide), while the latter are made of monocrystalline ceramic, commonly called sapphire by the manufacturers.63,64

Fig 15-22 Metal brackets.

Fig 15-23 Esthetic brackets.

For the translucent brackets to be esthetic and barely visible on the teeth, they should be made in shades resembling those of the teeth. On the other hand, the transparent ones should have a great transparency so as not to interfere with the tooth shade and fluorescence. Both types should present color stability.63,64 The patient’s tooth color is an important factor that needs to be considered when choosing an orthodontic appliance. The tooth color should be carefully assessed, especially in the maxillary anterior zone, which has the highest esthetic impact.63,64 Plastic orthodontic appliances were initially made of polycarbonate or polymethyl methacrylate (Plexiglas). The Plexiglas brackets did not last long because they became stained, were fragile, and broke easily. Moreover, this type of bracket wasted the energy of the orthodontic archwire due to deformation, so that only a small part of the orthodontic force was applied on the tooth. To prevent this shortcoming, attempts were made to increase its resistance by adding metal slots,

and by adding 15% to 30% of ceramic material to its composition. These modifications led not only to a higher resistance, but also to a decrease of the friction and color stability.62,65-68 Ceramic orthodontic appliances appeared in the 1980s as a more esthetically appealing alternative to plastic, and they met the patients’ expectations more readily (Fig 15-24). Plastic orthodontic appliances had a number of drawbacks: color instability, easy deformation and breaking, and increased friction and detachment from the teeth, while those made of mono- or polycrystalline ceramic proved to be more resistant to staining, and more color stable. However, the ceramic orthodontic brackets also presented shortcomings: a tendency to break easily, increased friction as compared to metal or plastic brackets, wearing down of the antagonist teeth, and, especially, the risk of enamel damage at removal.65-67,69 A change in the design of these brackets by the incorporation of a metal slot reduced friction and increased resistance.62,70 The possible damage to the enamel during appliance removal determined the modification of the retention procedure of polycrystalline ceramic appliances from a chemical to a purely mechanical one.70 As the manufacturing of polycrystalline ceramic brackets is easier, they are less expensive and more often used. Lingual orthodontic systems and orthodontic aligners are less-visible appliances, but in their case there are some clinical impediments and therapeutic limitations, unlike the esthetic orthodontic appliances that allow for a conventional orthodontic treatment. 15.2.2 Lingual orthodontic appliances Lingual orthodontic appliances were introduced in the 1970s in order to overcome the esthetic disadvantages of conventional buccal devices. One of the objectives of orthodontic treatment is dental esthetics. Lingual orthodontics is the only therapeutic method that does not affect the patient’s esthetic appearance during treatment. The emergence of these devices made orthodontic treatment more readily acceptable to adults, as they are invisible from the outside.

Fig 15-24 Comparison between the various types of orthodontic appliances.

The pioneers of this technique were Dr Craven Kurz, Dr Bob Smith, Dr Thomas Creekmore, and Dr Kinya Fujita. Several other orthodontists from Asia and Europe adapted and changed lingual appliances: they modified their size (thus increasing the interbracket distance, which led to increased elasticity of the archwire and patient comfort); they increased the bracket base (thus reducing the risk of detachment from the tooth); or they changed the bracket slot size to 0.018 × 0.025 inches. Despite these adaptations and changes, orthodontists were reluctant to use this type of appliance because of its complexity.71 There are many differences between lingual and labial appliances regarding manufacturing, bracket design, materials used, and even the method of bonding them to the tooth surface. In the past, these appliances were a new challenge, both for orthodontists and patients. Orthodontists soon discovered that the appliances required more dexterity and more time allocated to the patient for periodical follow-up. The most likely reason for their difficulty of use was their application on the oral surface of the teeth (which makes them barely visible). Moreover, the therapeutic outcomes were poorer than with conventional appliances. Also, the patient’s discomfort was significantly increased because of irritations to the tongue. Today, these orthodontic systems are increasingly used, as manufacturing improvements have allowed for a more simplified treatment with lingual appliances, as well as increased efficiency and patient comfort. • The advantages of lingual systems are:72,73 – They are the most esthetic. – They are comfortable for the lips and cheeks. – They have a tongue-training effect. – They deprogram the temporomandibular joint.

– They eliminate the possibility of decalcifications appearing on the labial enamel surface. – They allow for better observation of teeth alignment and the contour of facial soft tissues. – They enable a more rapid bite opening in cases of deep bite occlusion. – They allow for better cooperation from patients. – They reduce nocturnal bruxism. • The disadvantages of lingual systems are:72-75 – There is no direct view of the appliance, and it is difficult for the dentist to access the appliance. – Orthodontic archwires are difficult to insert and remove. – The wide variation of the morphology of the lingual surfaces, especially in the maxillary anterior zone, may determine incorrect, unpredicted alignment of these teeth. – Due to wide variations between teeth sizes, numerous first-order bends in the orthodontic archwire are necessary. – There is poor control of the torque due to the large distance between the lingual brackets and the buccal surface of the teeth. – The small interbracket distance in the anterior area makes it difficult to make compensating bends on the orthodontic archwire. – The precise placement of brackets is more important than with labial systems. – They require indirect bonding. – The duration of treatment may be longer than for labial systems, which in turn increases patient chair time. – They are more costly than buccal appliances. – They require additional laboratory procedures. – Certain surgical cases require the removal of lingual brackets before the surgery: segmental osteotomy, correction of open bites, and correction of class III malocclusions. – In certain class II surgical cases, the lingual brackets may interfere with the correct mandible advancement, which requires the expansion with overcorrection of the maxillary intercanine distance in order to perform the surgery. – The hygiene of the appliance is more difficult due to limited access. At present, lingual brackets comprise two types: standard brackets, whose placement on the teeth requires a laboratory procedure that creates the base adapted to the tooth morphology

(STb, Ormco 7th generation brackets, Ormco; Evolution, Adenta; magic, Dentaurum) and brackets that are individualized from the very beginning according to the patient’s teeth shapes (Incognito, 3M Unitek; Harmony, American Orthodontics). For most lingual appliances, the brackets incorporate information of the second and third order, and have a horizontal and a vertical slot. First-order information is introduced through the archwire, which is shaped in the form of a “mushroom”. The vertical slot has the advantage of making the insertion of the archwire easier, and allows for better control of the torque of anterior teeth in the retraction phase of treatment (Fig 15-25).71 The evolution of lingual brackets is toward those that also incorporate first-order information by the extension of the slot towards the lingual, in order to compensate the difference between the canine and the first premolar in the horizontal plane. This feature allows the use of a straight wire instead of a mushroom-form archwire, which makes these brackets much easier for the orthodontist to use. Also, self-ligating lingual brackets have been recently introduced.76

Fig 15-25 Lingual orthodontic appliance.

As they are easier to work with, many practitioners prefer fully individualized lingual brackets, despite the higher costs involved. In order to make such appliances, extremely accurate impressions of the maxillary and mandibular jaws are required. For this reason, a two-phase impression is preferred, which impresses the surface of each tooth with high precision, while the preferred materials are addition-cured silicones, due to their high dimensional stability that allows their casting as early as one week after the impressions have been taken. The models cast from these impressions are used for making an individual therapeutic

up model. When making the setup model, the technicians use Andrew’s six keys of occlusion as a guide for teeth alignment to create an ideal occlusion for the patient. Thereafter, a threedimensional scan of the therapeutic setup is obtained and processed by special computer-aided design/computer-aided manufacturing (CAD/CAM) software that manufactures the totally individualized lingual brackets (Fig 15-26). Due to high-precision scanning, the base of these brackets will adapt perfectly on the tooth surface. After creating the base, a bracket is selected for each tooth, having the adequate angulation, torque, and height. Certain lingual orthodontic systems make a digital setup, which eliminates the scanning stage, while the orthodontist can intervene directly in the brackets’ design. The manufacturing of the orthodontic archwire is also based on CAD/CAM technology, the archwires being designed to achieve the correct final position for each tooth (Fig 15-27).71

Fig 15-26 Therapeutic setup.

Fig 15-27 Design of the lingual orthodontic archwire.

Due to this state-of-the-art manufacturing technology, these lingual systems have a 100%

precision rate and are specially designed for excellent results and comfort. Another factor that contributes to the high efficiency of treatment with individualized lingual brackets is that the orthodontic archwires are made by observing the initial shape of each dental arch. The stability of the result depends very much on the preservation of the size and shape of the dental arch in every patient, and the precise correlation between the maxillary and mandibular arches. Lingual orthodontics is a therapeutic option attracting more and more attention both from orthodontists and patients. However, in order to obtain the expected results, the orthodontist should take into account a few guidelines for the selection of patients:77 The following are the clinical instances for which lingual orthodontic therapy is indicated: • Cases without teeth extractions: – Deep bite cases, Angle class I, with slight crowding, hypo- or normodivergent facial pattern. – Deep bite cases, Angle class I, with diastema or generalized spacing, hypo- or normodivergent facial pattern. – Deep bite cases, mild Angle class II, hypo- or normodivergent facial pattern. – Angle class II, division 2, with mandibular retrognathia. – Cases that need expansion. • Cases that need teeth extractions: – Class II, requiring extraction of the first maxillary premolars and second mandibular premolars. – Class II, treatable only by extracting the first maxillary premolars. – Cases with mild dentoalveolar biprotrusion, treated by extraction of the four first premolars, with minimum to medium requirement for posterior anchorage. • Difficult cases for lingual appliances: – Surgical cases. – Angle class III tendency. – Angle class II, requiring extraction of the four first premolars. – Patients with a mesiofacial pattern, but with a clockwise rotation tendency, in which the angle of the mandibular plane could become steeper during the treatment. – Patients having multiple dental restorations.

• Cases in which lingual appliances should be avoided: – Patients with temporomandibular joint disorders. – Patients without posterior occlusal stops. – Patients with a steep mandibular plane angle. – Massive prosthetic restorations in the anterior zone. – Short clinical crowns. – Cases with difficult anchorage requirements (ceased to be a strict contraindication with the advent of orthodontic mini-implants). – Severe class II malocclusions, with marked sagittal discrepancies. – Poor hygiene. – Untreated periodontal disease. – Unadaptable or demanding personality types. 15.2.3 Aligners Aligners are removable, personalized, almost invisible trays that make possible the treatment of dentoalveolar crowding or spacing, as well as mild orthodontic relapse that occurred during the retention phase of orthodontic treatment (Fig 15-28). Aligners offer the following benefits: they are esthetically pleasing, comfortable, based on simple mechanics. They are also cost-effective as they shorten patient chairtime. They are indicated mainly in cases requiring little dental movement: crowding less than 4 mm, especially from canine to canine; minor rotations, especially in the incisors; expansion; intrusion; and closure of spaces under 4 mm. They may also work as active or passive retainers. Aligners have come a long way in orthodontics, from simple devices following the teeth contour and allowing small dental movements, to sophisticated systems based on state-ofthe-art generation technologies, supported by serious research work. The early aligners were used for small dental adjustments. Their manufacturing was straightforward, by thermo vacuum forming on a setup model that reproduced the tooth or teeth position targeted. The most recent, high-performance aligners include 3D digital technology in the diagnosis and the therapeutic plan. Such systems treat increasingly varied and complex orthodontic cases, as they provide very good tridimensional control of the teeth position during therapy, and may be associated with other devices such as intra- or interarch elastics, fixed functional appliances (MARA, Herbst), or distalizing appliances. Orthodontic aligner treatment, regardless of the system used, includes the following stages:

• Documentation in order to establish the diagnosis, indication, and treatment plan: radiographs, intra- and extraoral photos, study models, occlusion analysis. • Impressions using high-fidelity materials, usually polyvinyl siloxane. • Design of the treatment plan and the setup model; the setup may be a stone cast plaster model or a virtual setup model and will help both the dentist and the patient foresee the final outcome of the treatment; at the same stage, the space needed for the teeth alignment is calculated, together with the amount of enamel to be reduced interproximally, and the teeth are subjected to the procedure. • Manufacturing of the aligners: a series of individualized aligners are made for each patient, who will wear them in succession in order to obtain the movement of the teeth position according to the therapeutic plan. • Beginning the treatment with aligners: each aligner may achieve a tooth movement of 0.5 mm and it is worn for two weeks, at least 22 hours a day; thereafter, the next aligner is worn, replacing the previous one. The advantages for patients of orthodontic treatments using aligners are: • They are almost invisible, which represents an important esthetic advantage, even when compared with esthetic brackets or other conventional orthodontic appliances. • The treatment is comfortable, as there are no elements that cause soft tissue irritation, such as in the case of brackets. • The trays are removable, and may be taken out during meals or for mouth cleaning; therefore, there are no food restrictions, and oral hygiene may be properly maintained.

Fig 15-28 Orthodontic aligners.

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INDEX A A-P-B see acid–primer–bonding ABF see aesthetical buccal flap abrasive mechanisms in toothpastes 165 absent vestibular plate 307 abutments see customized abutments acetone, all-ceramic restorations 261 acid activators 152 acid etching 136, 137, 144, 150, 153–154 acid monomers 140 acid–primer–bonding (A-P-B) 208 acrylic monomers 146 Acteon cameras 43 active tooth sensitivity 175 additive restorative methods, anterior teeth 194 adhesion procedures, posterior teeth restorations 236 adhesive bonding, porcelain laminate veneers 207–208 adhesive preparation, posterior teeth restorations 231 adhesive strips, vital tooth discoloration 168 adhesive systems, anterior teeth restorations 188 adhesive techniques 133–158 basic aspects 134–136 ceramics 150–154 hard dental tissue 137–149 dentin 140, 145–149 enamel 142–145, 147–149 etch-and-rinse bonding 138–139 glass-ionomers 138, 141–142 history 135–136 self-etch bonding 138, 139–141 strategies 137–142 types 134–135, 147–149 aesthetic buccal flap (ABF) 312 aesthetic pre-evaluative temporaries (APTs) 202, 203 aesthetic pre-recountering (APR) 202 aging, discoloration 163 aligners 331, 335 all-ceramic crowns anterior teeth restorations 214–219 classification 214 durability studies 219 In-Ceram 214, 215–216 with internal substructure 214–219 pressed ceramics 214, 216–217

without internal substruc ture 214–215 zirconium dioxide 217–219 posterior teeth restorations 252–255 with internal substructure 252–253 monolithic lithium disilicate crowns 253 monolithic zirconia crowns 253–254 without internal substruc ture 253 all-ceramic restorations conditioning 262–263 dental surface conditioning 262, 265 examinations 260–261 luting protocol 257, 266–267 occlusal relations 268–269 resin cement 258–259 silanization 263–264 all-ceramic systems CAD/CAM systems 106–111 crystalline ceramics 104–106 fabrication technology 98–111 pressed ceramic systems 100–103 refractory die techniques 98–100 all-in-one adhesives 136 aluminum oxide/Alumina (Al2O3) adhesive techniques 150 anterior tooth restorations 215, 216, 217 orthodontics 330 porous glass infiltration 104 posterior teeth restorations 252 alveolar crest, bone morphology 292–296 aminotriacetic acid 144 amorphous glass-ceramics 95 anterior teeth all-ceramic crowns 214–219 classification 214 durability studies 219 In-Ceram 215–216 with internal substructure 214–219 pressed ceramics 216–217 without internal substruc ture 214–215 zirconium dioxide 217–219 direct restorations 188–197 auxiliary components 190–191 clinical indications 191–192 composite layering 195–197 composite resins 192–195 materials 188–190 matrices 197 opacifiers 190–191 specific aspects 192–195

tints 190–191 gingival esthetics 44–45 porcelain laminate veneers 198–213 adhesive bonding 207–208 case selection 200–201 clinical indications 199 guided preparation 203–206 motivation 198–199 simulation of results 201–203 technology 206–207 treatment planning 200–201 restorations 187–228 all-ceramic crowns 214–219 customized abutments 220–226 direct 188–197 porcelain laminate veneers 198–213 apertures (photographic examinations) 50 depth of field 51–52 priority working modes 55, 56 APR see aesthetic pre-recountering APTs see aesthetic pre-evaluative temporaries arches dental/dentofacial esthetics 27–31 shape 27 symmetry 27–28, 29 argil ceramics 92 Artispot liquid contact markers 247 assistants, specific profile 3 at-home bleaching 168 auto camera working modes 56 automatic white balance, photographic examinations 60 B background color, intraoral image taking 66 beveled margins, posterior teeth restorations 231 BFEP see bonded functional esthetic prototypes bilateral flashes 58 Bioglass 174 biological properties of dental ceramics 93 biomimetic principle, posterior teeth restorations 242 Bis-GMA resins, adhesive techniques 135, 153–154 bizygomatic line 20 black triangles dental implants 293–294 gingival esthetics 327 bleaching non-vital tooth discoloration 181–184 vital tooth discoloration 164–168, 172–173, 175 see also whitening bonded functional esthetic prototypes (BFEP) 202–203

bonded porcelain restorations (BPRs) 205 bone morphology, alveolar crest 292–296 bone regeneration (GBR) 312 Bowen-formula resin 135, 153–154 bridges, in-office dental CAD/CAM technology 278 bruxism, posterior teeth restorations 253 buccal veneers 205 C CAD/CAM see computer-aided design/computer-aided manufacturing technology calcium-carboxylate & calcium-phosphate bonds 140–141 cameras 43, 49–68 compact cameras 55 device selection 55–56 DSLR 53, 56 exposure 50–51 flash 57–59, 60 focal length 53–55 fundamentals 50–60 image-file formats 59–60 intraoral photography 61–67 accessories 62 background color 66 contrastors 62 mirrors 62 portrait images 66 profile images 66 retractors 62 settings 61 JPEG image-files 59 lenses 57 magnification ratios 52–53 professional cameras 55–56 RAW image-files 60 TIFF image-files 60 white balance 60 carbamide peroxide, vital tooth discoloration 167, 171, 172, 174 carboxylic acid-based monomers, adhesive techniques 140 carboxylic compounds, adhesive techniques 151 caseinphosphopeptide-amorphous calcium phosphate (CPP-CP) 171, 174 case selection, anterior teeth restorations 200–201 cavities, posterior teeth restorations 238–239 cavity preparation/finishing, posterior teeth restorations 235–236 Celay, In-Ceram all-ceramic systems 104 cementation, all-ceramic restorations 258–259 cementoenamel junction (CEJ) non-vital tooth discoloration 180 ultraconservative dentistry 119 central incisors, dental/dentofacial esthetics 30 centric occlusion (CO), facial esthetics 319

centric relation (CR) facial esthetics 319 occlusal therapy 7 ultraconservative dentistry 127 ceramics adhesive techniques 150–154 chairside CAD/CAM technology 281 esthetic restorations 89–114 all-ceramic systems 98–111 biological properties 93 chemical properties 93 clinical indications 94 composition 92, 94 crystalline ceramics 94, 95–96, 104–106, 109 definition 91–93 fabrication technology 98–111 fusing temperature 94 glass-ceramics 94, 95–96 history 91 laboratory technology 94 microstructure 94–98 polycrystalline ceramics 94, 96–98, 110 properties 91–92, 93 structure 91–92 use 94–111 in-office dental CAD/CAM technology 280, 284 orthodontics 330–331 posterior teeth restorations 242, 246–249 ceramic veneers in-office dental CAD/CAM technology 278 optical properties of dental structures 41 refractory die techniques 100 CEREC systems chairside CAD/CAM technology 282 in-office dental CAD/CAM technology 274–277 milling 110–111 chairside CAD/CAM technology IPS Empress CAD 283–284 materials used 281–285 prosthetic restorations 284–285 VITABLOCS 281–283 Chairside Economical Restoration of Esthetic Ceramics systems see CEREC systems Chairside in-office dental CAD/CAM technology 273 chairside milling machines 276 chemical adhesion 134–135 chemical mechanisms in toothpastes 165 chemical properties of dental ceramics 93 chromophores 166 circular flashes 58 classical impressions 15

classical shade guides optical properties of dental structures 38 vital tooth discoloration 164 class II cavities, posterior teeth restorations 238–239 clinical case selection, anterior teeth restorations 200–201 clinical examinations vital tooth discoloration 163–164 see also examinations clinical indications anterior teeth restorations 191–192, 199 dental ceramics classifications 94 in-office dental CAD/CAM technology 276–279 clinical techniques, posterior teeth restorations 235–237 clinics 13–15 Clip (Voco) composite, posterior teeth restorations 244 cobalt oxides 92 coefficients of thermal expansion (CTE) 91, 93 collagen 140 collagen fibrils, adhesive techniques 141–142 color optical properties of dental structures 35 see also discoloration color analyses, optical properties of dental structures 38–39, 42–43 colorimeters, optical properties of dental structures 42, 43 color perception, optical properties of dental structures 40–41 color of restoration, modern dental practice 15 Coltosol (Coltène) composite, posterior teeth restorations 244 commissural line 20 commissures 25–26 communication modern dental practice 5–12 see also dentist–patient communication compact cameras 55 composite inlays, posterior teeth restorations 242 composite layering anterior teeth restorations 195–197 posterior teeth restorations 237 composite materials, anterior teeth restorations 189 composite resins anterior teeth restorations 189–190, 192–195 definitions 92 in-office dental CAD/CAM technology 284 posterior teeth restorations 233 ultraconservative dentistry 124–125 Composi-Tight GDS 3D matrix systems, posterior teeth restorations 239 computed tomography (CT) 279 computer-aided design/computer-aided manufacturing (CAD/CAM) technology all-ceramic systems 106–111 in-office 271–286 orthodontics 334

porcelain laminate veneers 206–207 posterior teeth restorations 247–249 provisional esthetic rehabilitation 82, 85 ultraconservative dentistry 125 cone-beam computed tomography (CBCT) 279 cones, optical properties of dental structures 40–41 contraindications anterior teeth 199 vital tooth discoloration 167 contrastors, intraoral photography 62 conventional feldspar ceramics 92 copper oxides 92 corks, smear adhesive layers 136 cosmetic toothpastes 166 couplers, adhesive techniques 152 CPP-CP see caseinphosphopeptide-amorphous calcium phosphate CR see centric relation crowns anterior teeth restorations 214–219 classification 214 durability studies 219 In-Ceram 214, 215–216 with internal substructure 214–219 pressed ceramics 214, 216–217 without internal substructure 214–215 zirconium dioxide 217–219 In-Ceram Alumina all-ceramic systems 104–106 in-office dental CAD/CAM technology 277–278 optical properties of dental structures 41 posterior teeth restorations 252–255 ultraconservative dentistry 119, 127 crystalline ceramics 94–96, 104–106, 109, 214, 330 CT see computed tomography CTE see coefficients of thermal expansion curing by light, all-ceramic restorations 266 cusps, posterior teeth restorations 240–241 customized abutments 220–226 fabrication technique 222–225 prosthetic factors 220–221 role of 221–222 surgical factors 220 D decalcification, adhesive techniques 142 delayed implant insertion 310–311 dental arches dental/dentofacial esthetics 27–31 shape 27 symmetry 27–28, 29 dental bleaching

non-vital tooth discoloration 181–184 vital tooth discoloration 164, 165, 166–168 see also whitening dental CAD/CAM technology all-ceramic systems 106–111 in-office 271–286 orthodontics 334 porcelain laminate veneers 206–207 posterior teeth restorations 247–249 provisional esthetic rehabilitation 82, 85 ultraconservative dentistry 125 dental ceramics 89–114 all-ceramic systems 98–111 biological properties 93 chemical properties 93 clinical indications 94 composition 92, 94 crystalline ceramics 94, 95–96, 104–106, 109 definition 91–93 fabrication technology 98–111 fusing temperature 94 glass-ceramics 94, 95–96 history 91 laboratory technology 94 microstructure 94–98 polycrystalline ceramics 94, 96–98, 110 properties 91–92, 93 structure 91–92 use 94–111 see also ceramics dental/dentofacial esthetics facial shape 21–22 facial symmetry 22 facial thirds 22 frontal view 20–22 general principles 19–48 dental arches 27–31 dentofacial relations 24–26 examination 20–23 optical properties 35–43 gingival esthetics 44–45 inclination of dental axes 31 maxillary incisal line 30 maxillary interincisal line 29 oral commissures 25–26 profile analysis 23 progression of dental dimension 30–31 rest position 24 shape 21–22, 32–34 smile lines 25, 26

smiling 22, 24–25 teeth arrangement 31 dental fluorosis 163 dental implants 8–9, 287–302 alveolar crest 292–296 diagnoses 288–289 edentulous zone 290 gum line shape 291 ideal position 296–300 interdental papillae 291 periodontal biotype 291–292 periodontal condition 290 remaining teeth position 290 roots 290 smile lines 289–290 soft tissue management 303–316 alveolus 304–307 delayed insertion 310–311 flaps 312–314 immediate insertion 308–309 staged implant insertion 312 success criteria 289–300 therapeutic sequence 288–289 dental surface conditioning 262, 265 dental technicians, modern dental practice 13–15 dentin adhesive techniques 140, 145–149 anterior teeth restorations 188, 195 optical properties 36–37 posterior teeth restorations 236, 237 dentist-supervised bleaching, vital tooth discoloration 168 dentist–patient communication 69, 70–80 digital smile design 79 direct mock-up 71–73 indirect mock-up 77–79 wax-up 73–76 depth of field, photographic examinations 51–52 design software, in-office dental CAD/CAM technology 275 diagnoses, dental implants 288–289 diamond rubbers, posterior teeth restorations 249 diaphragms (photographic examinations) 50 depth of field 51–52 digital dental photography 50 priority working modes 55, 56 digital dental photography 43, 49–68 compact cameras 55 device selection 55–56 exposure 50–51 flash 57–59, 60 focal length 53–55

fundamentals 50–60 image-file formats 59–60 intraoral 61–67 accessories 62 background color 66 contrastors 62 mirrors 62 portrait images 66 profile images 66 retractors 62 settings 61 JPEG image-files 59 lenses 57 magnification ratios 52–53 professional cameras 55–56 RAW image-files 60 TIFF image-files 60 white balance 60 digital intraoral scanner techniques, posterior teeth restorations 245 digital smile design (DSD) anterior teeth 201 dentist–patient communication 79–80 ultraconservative dentistry 120–121 direct mock-up 71–73 direct provisional esthetic rehabilitation 82, 83–84 direct restorations anterior teeth 188–197 auxiliary components 190–191 clinical indications 191–192 composite layering 195–197 composite resins 192–195 materials 188–190 matrices 197 opacifiers 190–191 specific aspects 192–195 tints 190–191 posterior teeth 230–239 adhesive preparation 231 beveled margins 231 class II cavities 238–239 finishing 235–236 layering techniques 233–235 materials 231–233 polishing 235 discoloration 159–186 non-vital tooth discoloration 179–185 bleaching techniques 183–184 bleach techniques 181–182 endodontic treatment 180 etiology 179–180

external bleaching techniques 183–184 gangrene 179 hemorrhage 179 internal bleaching techniques 183–184 pulp 179–180 restorative materials 180 root resorption 180 therapeutic methods 180–181 walking bleach techniques 181–182 whitening 180–181 vital tooth discoloration 160–184 bleaching techniques 166–168 clinical examination 163–164 etiology 160–163 extrinsic 160–161 fabrication techniques 168–173 internalized 161–162 intrinsic 162 microabrasion 166 mineralized tissues 174–175 model fabrication 168–173 oral hygiene 165–166 oxidative bleaching 173–174 pre-eruptive action factors 162–163 prophylactic cleaning 165–166 thermoformation technique 168–173 tray fabrication 168–173 treatment 164–175 whitening 165–166 dispersive adhesion 134–135 “dominated by dentin” restorations 195 dry-bonding 139 DSD see digital smile design DSLR cameras magnification ratios 53 working modes 56 durability studies, all-ceramic crowns 219 dyschromatopsia 41 E edentulous zone 290 electrostatic adhesion 134 embryogenetic theory 34 enamel adhesive techniques 142–145, 147–149 anterior teeth restorations 188 optical properties 36–37 posterior teeth restorations 236, 237 enamel composites, anterior teeth restorations 195 enamel sculpting, anterior teeth restorations 194

endodontic treatment modern dental practice 8 non-vital tooth discoloration 180 enzymatic mechanisms in toothpastes 165–166 etch-and-rinse bonding, adhesive techniques 138–139 etching adhesive techniques 153–154 all-ceramic restorations 263 see also acid etching ethanol, all-ceramic restorations 261 ethylenediamine tetraacetic acid 144 etiology, vital tooth discoloration 160–163 eugenol, all-ceramic restorations 258 examinations all-ceramic restorations 260–261, 268–269 photographic 49–68 compact cameras 55 device selection 55–56 exposure 50–51 flash 57–59, 60 focal length 53–55 fundamentals 50–60 image-file formats 59–60 intraoral photography 61–67 JPEG image-files 59 lenses 57 magnification ratios 52–53 professional cameras 55–56 RAW image-files 60 TIFF image-files 60 white balance 60 vital tooth discoloration 163–164 exposure, photographic examinations 50–51 extended veneers 205 external bleaching techniques, non-vital tooth discoloration 183–184 extractions, orthodontics 328–329 extraoral image taking, equipment 66–67 extrinsic tooth discoloration 160–161 eyebrows line 20 F fabrication technology all-ceramic systems 98–111 customized abutments 222–225 porcelain laminate veneers 206–207 posterior teeth restorations 242–244, 245–249 vital tooth discoloration 168–173 facial esthetics orthodontics 319–320 see also dental/dentofacial esthetics

facial profile analysis 23 facial shape 21–22, 33 facial symmetry 22 facial thirds, dental/dentofacial esthetics 22 Farnsworth-Munsell color vision tests 41 feldspathic ceramics 92 feldspathic inlays, posterior teeth restorations 245–246 feldspathic porcelain all-ceramic crowns 214 in-office dental CAD/CAM technology 280 porcelain laminate veneers 206 finishing, posterior teeth restorations 235–236 fissures, posterior teeth restorations 240–241 fixed lenses 57 flaps, soft tissue implants 312–314 flash (photographic examinations) 57–59, 60 fluorescence dental ceramics 92 optical properties of dental structures 36 fluorosis 163 focal length, photographic examinations 53–55 four-increment layering techniques, posterior teeth restorations 235 frontal view dental/dentofacial esthetics 20–22 intraoral image taking 63–64 fusing temperatures, dental ceramics 94 G gangrene, non-vital tooth discoloration 179 GBR see guided bone regeneration gel phase adhesive techniques 141 glass-ionomers 142 gels posterior teeth restorations 248 vital tooth discoloration 168, 171 GICs see glass-ionomer cements gingival esthetics dental/dentofacial esthetics 44–45 orthodontics 324–327 zenith 44–45 gingival inflammation all-ceramic restorations 266–267 posterior teeth restorations 244 glass ceramics anterior teeth restorations 214, 216–217 in-office dental CAD/CAM technology 285 leucite 95–96, 216–217 surface conditioning 262 use 94, 95

glass infiltration, crystalline ceramics 104–106 glass-ionomer bonding 141–142 glass-ionomer cements (GICs) 92, 181, 242 glass-ionomers, adhesive techniques 138 glaze systems, in-office dental CAD/CAM technology 280 glycerin, all-ceramic restorations 266 glycerin gels, posterior teeth restorations 248 glycerin try-in pastes 123 glycerophosphoric acid dimethacrylate 144 gnathion facial regions 20, 23 golden number (Levin) 30 green stage zirconia 253 grooves, posterior teeth restorations 240–241 guided bone regeneration (GBR) 312 gum line shape 291 gummy smile 327–328 gypsum models, porcelain laminate veneers 206 H halo effect 195 hard dental tissue adhesive techniques 137–149 dentin 140, 145–149 enamel 142–145, 147–149 etch-and-rinse bonding 138–139 glass-ionomers 138, 141–142 history 135–136 self-etch bonding 138, 139–141 strategies 137–142 types 134–135, 147–149 HEMA acrylic monomer, adhesive techniques 146 hemorrhage, non-vital tooth discoloration 179 high-leucite content glass-ceramics 95–96 high-translucency blocks, chairside CAD/CAM technology 283 horizontal layering techniques, posterior teeth restorations 233–234 hue, optical properties of dental structures 35 hybrid ceramics, prosthetic restorations 284 hybridization, adhesive techniques 137 hybrid layers, adhesive techniques 146–147 hydrofluoric acid adhesive techniques 150, 153–154 all-ceramic restorations 262 hydrogen peroxide 166–167, 171, 172, 183–184 N-(2-hydroxy-3-methacryloxypropyl)N-phenyl-glycine 144 hydroxyapatite adhesive techniques 138, 140–144 vital tooth discoloration 171, 174 hygiene, vital tooth discoloration 165–166 I

illumination, ultraconservative dentistry 116, 118 image-file formats, photographic examinations 59–60 imaging systems, optical properties of dental structures 42 immediate implant insertion 308–309 implants 8–9, 287–302 alveolar crest 292–296 diagnoses 288–289 edentulous zone 290 gum line shape 291 ideal position 296–300 interdental papillae 291 periodontal biotype 291–292 periodontal condition 290 remaining teeth position 290 roots 290 smile lines 289–290 soft tissue management 303–316 alveolus 304–307 delayed insertion 310–311 flaps 312–314 immediate insertion 308–309 staged implant insertion 312 success criteria 289–300 therapeutic sequence 288–289 impressions, modern dental practice 15 In-Ceram all-ceramic crowns anterior teeth restorations 214, 215–216 posterior teeth restorations 252 In-Ceram all-ceramic systems 104–106 incisal edge veneers 205 incisal line, dental/dentofacial esthetics 30 incisors, dental/dentofacial esthetics 30 inclination of dental axes, dental/dentofacial esthetics 31 incremental layering techniques, posterior teeth restorations 235 indications anterior teeth restorations 191–192, 199 in-office dental CAD/CAM technology 276–279 vital tooth discoloration 167 indirect mock-up 15, 77–79 see also wax-up indirect provisional esthetic rehabilitation 82, 84–85 indirect restorations posterior teeth 240–251 fabrication techniques 242–244, 245–249 inlays and onlays 240–244, 245–249 porcelain inlays 245–249 temporary restorations 244–245 infiltration ceramics, chairside CAD/CAM technology 281 infiltration etching, all-ceramic restorations 263 inflamed gingival tissue, dental/dentofacial esthetics 44

inlays in-office dental CAD/CAM technology 276–277 posterior teeth restorations 240–244, 245–249 in-office bleaching 172–173, 175 in-office dental CAD/CAM technology 271–285 bridges 278 ceramic veneers 278 Chairside 273 clinical indications 276–279 crowns 277–278 design software 275 inlays 276–277 laboratory systems 273 materials used 281–285 IPS Empress CAD 283–284 prosthetic restorations 284–285 VITABLOCS 281–283 milling centers 273 milling machines 275 onlays 276–277 overlays 276–277 restoration esthetics 280 restoration types 276–279 scanners 272, 274–275 surgical guides 279 system description 272–275 inorganic peroxides, non-vital tooth discoloration 180 instrumental color analyses 42–43 intercuspation, occlusal therapy 7 interdental papillae 291 interdisciplinary communication, modern dental practice 5–12 interincisal line, dental/dentofacial esthetics 29 internal bleaching techniques, non-vital tooth discoloration 183–184 internalized tooth discoloration 161–162 interpenetrating phase, crystalline ceramics 96 interpupillary line 20 intraoral image taking background color 66 portrait images 66 profile images 66 intraoral photography 61–67 accessories 62 contrastors 62 extraoral equipment 66–67 image taking 63–66 mirrors 62 retractors 62 settings 61 intraoral scanner techniques 245 intrapulpal hemorrhage 179

intrinsic tooth discoloration 162 IPS Empress all-ceramic systems 100–103 IPS Empress CAD 283–284 iron oxides 92 Ishihara color vision tests 41 isolation posterior teeth restorations 235, 247–248 ultraconservative dentistry 116, 118–119 ISO sensitivity, photographic examinations 55 Ivoclar Vivadent IPS Empress all-ceramic systems 100–103 ivory wax-up, anterior teeth 201–202 J Joint Photographic Experts Group (JPEG) image-files 59 L laboratory systems, in-office dental CAD/CAM technology 273 laboratory technicians, modern dental practice 13–15 laboratory technology dental ceramics classifications 94 porcelain laminate veneers 206–207 posterior teeth restorations 245–249 laminate veneers anterior teeth restorations 198–213 adhesive bonding 207–208 case selection 200–201 clinical indications 199 guided preparation 203–206 motivation 198–199 simulation of results 201–203 technology 206–207 treatment planning 200–201 lanthanide oxides 92 laser etching 150 laser-whitening 173 lateral view, intraoral image taking 63–64 layering techniques anterior teeth restorations 195–197 posterior teeth restorations 233–235, 237 LCD screens 55 LED lighting, all-ceramic restorations 266 lenses, photographic examinations 57 leucite glass ceramics 95–96, 216–217 light curing, all-ceramic restorations 266 lightness, optical properties of dental structures 35 Linearguide 3D Master shade guides, vital tooth discoloration 164 lines used for facial analyses 20 lingual orthodontic appliances 331–335 lithium disilicate 96, 217 CAD/CAM systems 109

posterior teeth restorations 252, 253, 254 lithium silicate 285 low-leucite content glass-ceramics 95 low-pH etchers 139 luting protocol for all-ceramic restorations 257, 266–267 M “macro” lenses 57 macro/micro resin tags, adhesive techniques 145 “macro” working camera modes 55 magnification, ultraconservative dentistry 116–118 magnification ratios, photographic examinations 52–53 mandibular area 320 mandibular occlusal view, intraoral image taking 65 manganese oxides 92 manual camera working modes 56 manual white balance, photographic examinations 60 margin placement, posterior teeth restorations 243–244 matrices anterior teeth restorations 197 posterior teeth restorations 239 maxillary area 320 maxillary central incisors 30 maxillary incisal line 30 maxillary interincisal line 29 maxillary occlusal view 65–66 maximum intercuspation (MI), occlusal therapy 7 MDP see 10-methacryloyloxydecyl dihydrogen phosphate mechanical adhesion 134–135 mechanical scanners 274 mesio-occlusodistal cavities, posterior teeth restorations 239 metamerism, optical properties of dental structures 40 3-methacryloxypropyltrimethoxysilane molecules 263 γ-methacryloxypropyl-trimethoxysilane (γ-MPTS) 151 10-methacryloyloxydecyl dihydrogen phosphate (MDP) 151, 262–263 methanol, all-ceramic restorations 261 methyl chloride, all-ceramic restorations 261 MI see maximum intercuspation microabrasion, vital tooth discoloration 166 microfill composite resin restorations, anterior teeth 191 microhybrid composite resin restorations, anterior teeth 189, 191 microstructure of dental ceramics 94–98 microveneers 205 milling, all-ceramic systems 106–111 milling centers 273 milling machines 275 mineralized tissues, vital tooth discoloration 174–175 minocycline 163 mirror-like zirconia 253 mirrors, intraoral photography 62

mock-up dentist–patient communication direct 71–73 indirect 77–79 ultraconservative dentistry 120–121 model fabrication, tooth discoloration 168–173 modern dental practice 1–18 clinics 13–15 dental technicians 13–15 endodontic therapy 8 implant therapy 8–9 interdisciplinary communication 5–12 laboratory technicians 13–15 occlusal therapy 7 orthodontic therapy 7–8 periodontal therapy 9–12 relationships 5–12 restorative therapy 6 specific profile 2–4 whitening therapy 6–7 modern dentistry, ultraconservative 116–126 modified indirect provisional esthetic rehabilitation 85 moist bonding 139 monocrystalline ceramics, orthodontics 330 monolithic crowns anterior teeth restorations 214–215 posterior teeth restorations 252, 253 monolithic lithium disilicate crowns, posterior teeth restorations 253 monolithic zirconia crowns, posterior teeth restorations 253–254 monomeric resin infiltration, adhesive techniques 139–140 morphological layering techniques, anterior teeth 195–197 γ-MPTS see γ-methyacryloxypropyl-trimethoxysilane multiple idiopathic cervical root resorption (MICRR) 180 multiple morphological layering techniques, anterior teeth 195–197 N N-(2-hydroxy-3-methacryloxypropyl)N-phenyl-glycine 144 nanoceramics, in-office dental CAD/CAM technology 284 nanofill composite resin restorations 190, 191 nanohybrid composite resin restorations 191 nanohydroxyapatite 171, 174 narrow smiles 26 Nathoo discoloration classifications 161 non-etchable ceramics, posterior teeth restorations 248 non-vital tooth discoloration 179–185 bleaching techniques 183–184 bleach techniques 181–182 endodontic treatment 180 etiology 179–180 external bleaching techniques 183–184

gangrene 179 hemorrhage 179 internal bleaching techniques 183–184 pulp 179–180 restorative materials 180 root resorption 180 therapeutic methods 180–181 walking bleach techniques 181–182 whitening 180–181 no-prep veneers 205 O oblique layering techniques, posterior teeth restorations 234–235 occlusal relationships all-ceramic restorations 268–269 posterior teeth restorations 242 occlusal therapy, modern dental practice 7 occlusion, facial esthetics 319 onlays in-office dental CAD/CAM technology 276–277 posterior teeth restorations 240–244, 246–249 opacifiers, anterior teeth restorations 190–191 opalescence, optical properties of dental structures 36 operating field isolation, posterior teeth restorations 235 optical properties of dental structures 35–43 general considerations 35–36 influential factors 36–37 instrumental color analyses 42–43 tooth analyses 38–43 value-based shade guides 38, 39 visual color analyses 38–42 visual selection of shades 40–42 optical scanners 274 oral commissures, dental/dentofacial esthetics 25–26 oral hygiene, vital tooth discoloration 165–166 oral mucosa, vital tooth discoloration 175 organic peroxides, non-vital tooth discoloration 180 orthodontics 317–337 extractions 328–329 facial esthetics 319–320 gingival esthetics 324–327 smile esthetics 327–328 therapeutic options 330–335 aligners 331, 335 ceramic appliances 330–331 lingual orthodontic appliances 331–335 plastic appliances 330–331 orthodontic therapy, modern dental practice 7–8 oval face 21 overbite 322

overlays, in-office dental CAD/CAM technology 276–277 over-the-counter products, vital tooth discoloration 168 oxidation-reduction, non-vital tooth discoloration 180 oxidative bleaching, vital tooth discoloration 173–174 oxide crystalline ceramics, chairside CAD/CAM technology 281 P Palodent matrix system 239 panoramic radiographs 164 papillae, dental implants 291 passive tooth sensitivity 175 patient types 70 PBRs see porcelain bonded restorations pear-shaped face 21 periodontal biotype, dental implants 291–292 periodontal condition, dental implants 290 periodontal examinations, gingival esthetics 44 periodontal pockets, posterior teeth restorations 242 periodontal therapy, modern dental practice 9–12 peroxide-based products non-vital tooth discoloration 180, 183–184 vital tooth discoloration 166–167, 168, 171, 172, 174 personal assistants, specific profile 3 personnel, specific profile 3 PFM see porcelain fused to metal crowns phosphoric acid derivatives 144 phosphoric acid gel 138 photographic examinations 49–68 background color 66 compact cameras 55 device selection 55–56 exposure 50–51 flash 57–59, 60 focal length 53–55 fundamentals 50–60 image-file formats 59–60 intraoral image taking 66 intraoral photography 61–67 accessories 62 contrastors 62 image taking 63–66 mirrors 62 retractors 62 settings 61 JPEG image-files 59 lenses 57 magnification ratios 52–53 portrait images 66 professional cameras 55–56 profile images 66

RAW image-files 60 TIFF image-files 60 white balance 60 pigments 92 pits, posterior teeth restorations 240–241 plastic appliances, orthodontics 330–331 plugs, smear adhesive layers 136 PLVs see porcelain laminate veneers polishing, posterior teeth restorations 235 polycrystalline ceramics 94, 96–98, 110, 214, 330 polyvinylsiloxane (PVS) 73 porcelain all-ceramic crowns 214 all-ceramic restorations 262–263 in-office dental CAD/CAM technology 280 posterior teeth restorations 245–249, 254 ultraconservative dentistry 122–123, 125 porcelain bonded restorations (PBRs) 244 porcelain fused to metal (PFM) crowns anterior teeth restorations 215–216 posterior teeth restorations 252 ultraconservative dentistry 119, 124, 127 porcelain laminate veneers (PLVs) anterior teeth restorations 198–213 adhesive bonding 207–208 case selection 200–201 clinical indications 199 guided preparation 203–206 motivation 198–199 simulation of results 201–203 technology 206–207 treatment planning 200–201 porcelain veneers, ultraconservative dentistry 122–123 porous structures, crystalline ceramics 104–106 portrait images, intraoral image taking 66 posterior teeth all-ceramic crowns 252–255 monolithic lithium disilicate crowns 253 monolithic zirconia crowns 253–254 without internal substructure 253 direct restorations 230–239 adhesive preparation 231 beveled margins 231 class II cavities 238–239 clinical techniques 235–237 finishing 235–236 layering techniques 233–235 materials 231–233 polishing 235 indirect restorations 240–251

fabrication techniques 242–244, 245–249 inlays and onlays 240–244, 245–249 porcelain inlays 245–249 temporary restorations 244–245 restorations 229–256 all-ceramic crowns 252–255 direct 230–239 indirect 240–249 pottery ceramics 92 pre-eruptive action factors, vital tooth discoloration 162–163 prefabricated ceramic blocks, CAD/CAM systems 106–111 prehydrolyzed single-liquid silane primers 152 pre-sintered zirconia blocks 253 pressed-ceramic inlays/onlays 246–247 pressed ceramics 100–103, 214, 216–217 pressed veneers 206–207 primers acid–primer–bonding 208 adhesive techniques 152 posterior teeth restorations 248 priming steps, adhesive techniques 139 priority camera working modes 55, 56 prism effect, anterior teeth restorations 193 professional cameras 55–56 profile analyses dental/dentofacial esthetics 23 facial esthetics 320 profile images, intraoral image taking 66 profiles in dental practice management 2–4 progression of dental dimension, dental/dentofacial esthetics 30–31 prophylactic cleaning 165–166 prosthetic factors, customized abutments 220–221 prosthetic restorations, chairside CAD/CAM technology 284–285 provisional esthetic rehabilitation 69, 81–85 CAD/CAM techniques 82, 85 direct technique 82, 83–84 indirect technique 82, 84–85 modified indirect technique 85 proximal microveneers 205 pulp non-vital tooth discoloration 179–180 optical properties 36–37 PVS see polyvinylsiloxane Q quartz ceramics 94, 95 R radiographs, vital tooth discoloration 164 RAW image-files, photographic examinations 60

Real Life, VITABLOCS 282–283 recessed gingival tissue 44 rectangular face 21 redox reactions 180 refractory die techniques 98–100 rehabilitation, see also provisional esthetic rehabilitation relationships, modern dental practice 5–12 resins adhesive techniques 135, 139–140, 153–154 all-ceramic restorations 258–259 anterior teeth restorations 189–191, 192–195 in-office dental CAD/CAM technology 284 posterior teeth restorations 233 ultraconservative dentistry 124–125 resin tags, adhesive techniques 144–145 restorations all-ceramic conditioning 262–263 dental surface conditioning 262, 265 examinations 260–261 luting protocol 257, 266–267 occlusal relations 268–269 resin cement 258–259 silanization 263–264 anterior teeth 187–228 all-ceramic crowns 214–219 customized abutments 220–226 direct 188–197 porcelain laminate veneers 198–213 ceramics 89–114 all-ceramic systems 98–111 biological properties 93 chemical properties 93 clinical indications 94 composition 92, 94 crystalline ceramics 94, 95–96, 104–106, 109 definition 91–93 fabrication technology 98–111 fusing temperature 94 glass-ceramics 94, 95–96 history 91 laboratory technology 94 microstructure 94–98 polycrystalline ceramics 94, 96–98, 110 properties 91–92, 93 structure 91–92 use 94–111 color/modern dental practice 15 in-office dental CAD/CAM technology 276–279, 280 posterior teeth 229–256

all-ceramic crowns 252–255 direct 230–239 indirect 240–251 vital tooth discoloration 175 restorative margins, ultraconservative dentistry 122 restorative materials, non-vital tooth discoloration 180 restorative therapy, modern practice 6 rest position dentofacial relations 24 retractors, intraoral photography 62 rhodium-coated mirrors, intraoral photography 62 ring flashes 58 root resorption, non-vital tooth discoloration 180 roots, dental implants 290 S sandblasting, adhesive techniques 150 SAP see sex, age, and personality indices sapphire 330 satellite systems, photographic examinations 58 saturation, optical properties of dental structures 35 scalloping 168, 170 scanned impressions, modern dental practice 15 scanners, in-office dental CAD/CAM technology 272, 274–275 scanner techniques, posterior teeth restorations 245 scanning electron microscopes (SEM), adhesive techniques 143 sculpting, anterior teeth restorations 194 secondary crystalline ceramics 95–96 selective infiltration etching (SIE) 263 self-etch bonding, adhesive techniques 138, 139–141 SEM see scanning electron microscopes semi-professional cameras 55 sensitivity of teeth, vital tooth discoloration 174–175 sex, age, and personality (SAP) indices 33 shade guides optical properties of dental structures 38, 39, 41 vital tooth discoloration 164 shade selection, optical properties of dental structures 40–42 shutters, photographic examinations 50–51 shutter-speed camera working modes 56 silane coupling agents 152–154 silane primers 152 silanes, posterior teeth restorations 248 silanization, all-ceramic restorations 263–264 silica-based ceramics 94–96, 214, 217, 281, 285 Silver Plus G ring systems, posterior teeth restorations 239 single-component silane, all-ceramic restorations 264 single-liquid silane primers 152 single-phase polycrystalline ceramics 96–98 single-tooth radiographs 164 smear adhesive layers 135–136

smiling 22, 24–26, 289–290, 327–328 see also digital smile design sodium perborate 180–181 soft tissue management 303–316 alveolus 304–307 delayed implant insertion 310–311 flaps and implant insertion 312–314 immediate implant insertion 308–309 staged implant insertion 312 software, in-office dental CAD/CAM technology 275 Sopro 717 Acteon cameras 43 spectrophotometers 42–43 Spinell, In-Ceram all-ceramic systems 104, 215 staged implant insertion 312 stain systems, in-office dental CAD/CAM technology 280 subgingivally-placed veneers, ultraconservative dentistry 123 subgingival margin preparation, ultraconservative dentistry 122 submental line 20 subnasal line 20 subs-tractive restorative methods, anterior teeth 194 surgical factors, customized abutments 220 surgical guides, in-office dental CAD/CAM technology 279 survival studies, posterior teeth restorations 254 T Tagged Image File Formats (TIFF) 60 teeth, see also dental... teeth arrangement 31 Teflon tapes, all-ceramic restorations 261, 266 temperature, dental ceramics 94 temporary restorations, posterior teeth 244–245 tetracycline 162–163 therapeutic options dental implants 288–289 modern dental practice 8–9 endodontic 8 implant 8–9 occlusal 7 periodontal 9–12 restorative 6 non-vital tooth discoloration 180–181 orthodontics 330–335 aligners 331, 335 ceramic appliances 330–331 lingual orthodontic appliances 331–335 plastic appliances 330–331 thermoformation technique, vital tooth discoloration 168–173 thick periodontal structure, gingival esthetics 44 thick vestibular plate 305 thin periodontal structure, gingival esthetics 44

thin vestibular plate 306 three-increment layering techniques, posterior teeth restorations 235 three-liquid primers, adhesive techniques 152 three-quarter veneers 205 through the lens (TTL) flash functions 58 TIFF see Tagged Image File Formats tints, anterior teeth restorations 190–191 titanium oxides 92 tooth discoloration see discoloration toothpastes 165–166 tooth root resorption, non-vital tooth discoloration 180 tooth sensitivity, vital tooth discoloration 174–175 tooth size, dental/dentofacial esthetics 34 tooth surfaces, posterior teeth restorations 240–241 tooth vitality, posterior teeth restorations 242 total acid etch 136 total-etch techniques, adhesive techniques 146 traditional feldspar ceramics 92 translucency/transparency, optical properties of dental structures 36 tray fabrication, vital tooth discoloration 168–173 treatment plans anterior teeth restorations 200–201 provisional esthetic rehabilitation 69, 81–85 vital tooth discoloration 164–175 triangular face 21 trichion facial regions 20 Triluxe, VITABLOCS 282 TTL see through the lens flash functions twin flashes 58 two-component silanes all-ceramic restorations 264 posterior teeth restorations 248 two-liquid primers, adhesive techniques 152 U ultraconservative dentistry 115–132 composite resins 124–125 function 127–131 illumination 116, 118 isolation 116, 118–119 magnification 116–118 materials 124–125 modern 116–126 porcelain 122–123, 125 postoperative clinical examination 126 preparation 119–124 unhydrolyzed single-liquid silane primers 152 universal adhesives 136 uranium oxides 92

V value-based shade guides optical properties of dental structures 38, 39, 41 vital tooth discoloration 164 value (lightness), optical properties of dental structures 35 VDO see vertical dimension of occlusion veneers anterior teeth restorations 198–213 adhesive bonding 207–208 case selection 200–201 clinical indications 199 guided preparation 203–206 motivation 198–199 simulation of results 201–203 technology 206–207 treatment planning 200–201 in-office dental CAD/CAM technology 278 optical properties of dental structures 41 refractory die techniques 100 ultraconservative dentistry 122–123 vertical dimension of occlusion (VDO) occlusal therapy 7 ultraconservative dentistry 127, 131 very narrow smiles 26 very wide smiles 26 visual color analyses, optical properties of dental structures 38–42 visual selection of shades 40–42 VITABLOCS, chairside CAD/CAM technology 281–283 Vita Classical shade guides, optical properties of dental structures 38, 39 Vita Easyshade, optical properties of dental structures 42 Vita Enamic prosthetic restorations 284 vital tooth discoloration 160–184 bleaching techniques 166–168 clinical examination 163–164 etiology 160–163 extrinsic 160–161 fabrication techniques 168–173 internalized 161–162 intrinsic 162 microabrasion 166 mineralized tissues 174–175 model fabrication 168–173 oral hygiene 165–166 oxidative bleaching 173–174 pre-eruptive action factors 162–163 prophylactic cleaning 165–166 thermoformation technique 168–173 tray fabrication 168–173 treatment 164–175 whitening 165–166

Vitapan 3D Master shade guides 164 Vitapan Classical shade guides 164 Vita Suprinity prosthetic restorations 285 V-Ring matrix systems, posterior teeth restorations 239 W walking bleach techniques 181–182 wax-up anterior teeth 201–202 dentist–patient communication 73–76 modern dental practice 15 ultraconservative dentistry 120–121 wet bonding 139 white balance, photographic examinations 60 whitening non-vital tooth discoloration 180–181 therapy 6–7 vital tooth discoloration 165–166 wide smiles 26 Willi Geller models 206 window veneers 205 working camera modes 55, 56 X X-Rite colorimeters 43 Z zeneers 207 zinc oxyphosphate 125 zirconium dioxide/Zirconia (ZnO2) 104, 215, 262–263 anterior teeth restorations 217–219 lithium silicate glass ceramic 285 posterior teeth restorations 252, 253–254 prefabricated ceramic blocks 107–110 ultraconservative dentistry 125 zygion facial points 20