Temporary Anchorage Devices in Orthodontics [2 ed.] 9780323609333

Table of contents :
Front Cover
IFC
Temporary Anchorage Devices in Orthodontics
Temporary Anchorage Devices in Orthodontics
Copyright
Contents
Preface
Contributors
Acknowledgements
Dedication
I -
Biology and Biomechanics of Skeletal Anchorage
1 -
Biomechanics Principles in Mini-Implant Driven Orthodontics
Introduction
Approaches for Studying Tooth Movement
Basic Mechanical Concepts
Force
Force Diagrams and Vectors
Principle of Transmissibility
The Effect of Two or More Forces on a System: Vector Addition
The Directional Effects of Force: Vector Resolution
Center of Resistance, Center of Gravity, and Center of Mass
Moment (Torque)
Couple (A Type of Moment)
Concept of Equilibrium
Equilibrium in Orthodontics (The Quasi-Static System)
Principle of Equivalent Force Systems
Application of Equivalent Force Systems: Moving the Force System to a Different Location
Center of Rotation
Estimating the Center of Rotation
Types of Tooth Movement (Fig. 1.13)
Controlled Tipping
Root Movement
Moment-to-Force (M/F) Ratios
1. Altering the Point of Force Application (Fig. 1.14)
2. Altering the Moment-to-Force Ratio (Fig. 1.15)
Space Closure Mechanics With Mini-Implants
Mechanical differences in incisor retraction between MIs and conventional techniques
Basic Model for Space Closure
Sequela of Phase IV: Distalization Effect of Mini-Implant Assisted Retraction
Mechanical Factors Affecting Incisor Retraction
The “Hybrid Model” With Mini-Implant Anchorage
Conclusions
II -
Diagnosis andTreatment Planning
2 -
Three-Dimensional Evaluation of Bone Sites for Mini-Implant Placement
Key Pointers for Preoperative Treatment Planning of TADs Using Three-Dimensional Imaging
Three-Dimensional Evaluation of a Potential TAD Site in the Palate
Three-Dimensional Evaluation of a Potential TAD Site in the Maxillary Posterior Area
Three-Dimensional Evaluation of a Potential TAD Site in the Buccal Shelf Area
3 - Success Rates and Risk Factors Associated With Skeletal Anchorage
Introduction
Site of Placement and Success Rates
Buccal Alveolar Mini-Implants/Interradicular Mini-Implants
Palatal Mini-Implants
Extraalveolar Mini-Implants
Risk Factors
Conclusion
III -
Palatal Implants
4 -
Space Closure for Missing Upper Lateral Incisors
Therapy Options to Replace Upper Lateral Incisors
Prosthetic–Implantologic Solution
Orthodontic Space Closure: Anchorage and Biomechanics
Palatal Screw Selection and Insertion
Mesial Sliding Appliance
Interdisciplinary Aspects of Finishing When Closing the Space
The First Premolar
Torque
Intrusion
Gingivectomy
The Canine
Torque
Extrusion
Occlusion After Space Closure
Conclusion
5 - Predictable Management of Molar Three-Dimensional Control with i-station
Extraalveolar Anchorage Through the i-station Device
Light and Efficient Force Systems
Mechanics to Apply Labial Crown Torque to the Incisors
Case 1
Treatment Plan and Alternatives
Treatment Progress
Treatment Result
Case 2
Treatment Plan and Alternatives
Treatment Progress
Treatment Result
Summary
6 - MAPA: The Three-Dimensional Mini-Implants-Assisted Palatal Appliances and One-Visit Protocol
Introduction
Surgical Guide Fabrication
Mini-implants Application
Appliance Fabrication
Clinical Cases
Class III Growing Patients
Class II Patient
Narrow Maxilla
Asymmetrical Cases
Conclusion
7 - Asymmetric Noncompliance Upper Molar Distalization in Aligner Treatment Using Palatal TADs and the Beneslider
Upper Distalization in Aligner Treatment
Optimal Insertion Sites for Mini-Implants
Clinical Procedure and Rationale of the Beneslider
How to Combine Beneslider and Aligners, Strategies and Clinical Tips
Clinical Case 1: Simultaneous Start of Aligner and Distalization
Clinical Case 2: Aligner Start During Distalization
Clinical Considerations
Conclusions
IV -
Skeletal Plates
8 -
Nonextraction Treatment of Bimaxillary Anterior Crowding With Bioefficient Skeletal Anchorage
Case 1
Chief Complaint
Diagnosis and Case Summary (Tables 8.1–8.4; Figs. 8.1 and 8.2)
Treatment Options (Tables 8.5 and 8.6; Figs. 8.3–8.14)
Case 2
Chief Complaint
Diagnosis and Case Summary (Tables 8.7–8.10; Figs. 8.15 and 8.16)
Treatment Options (Tables 8.11 and 8.12; Figs. 8.17–8.28)
9 - Managing Complex Orthodontic Problems With Skeletal Anchorage
Introduction
Case 1: Reversing the Effects of Failed Growth Modification/Camouflage in a Skeletal Class II
Problem List
Treatment Goals
Considerations
Treatment (Phase 1)
Summary
Problem List (After Early Treatment)
Considerations
Treatment
Summary
Case 2: Decompensation of a Retreatment Case Presenting With Bimaxillary Dental Protrusion and Skeletal Class II Malocclusion
Problem List
Treatment Goals
Considerations
Treatment
Summary
Case 3: A Complex Interdisciplinary Challenge Compromised by Previous Restorative Treatment
Problem List
Treatment Goals
Considerations
Treatment
Summary
Case 4: A Complex Interdisciplinary Problem Characterized by Tooth Surface Loss, Dental Asymmetry, and Crowding
Problem List
Treatment Goals
Considerations
Treatment
Summary
Case 5: A Progressive Condylar Resorption Case That Developed Into a Class II Openbite
Problem List
Treatment Goals
Considerations
Treatment
Summary
V -
Zygomatic Implants
10 -
Zygomatic Miniplate-Supported Openbite Treatment: An Alternative Method to Orthognathic Surgery
Openbite Malocclusion and Treatment
Zygomatic Anchorage: Multipurpose Implant
Surgical Method for Multipurpose Implant Placement
Possible Complications
Removal of Multipurpose Implant
New-Generation Openbite Appliance
Fabrication
Wire Bending
Acrylic Cap
Clinical Application
Retention of Openbite Treatment
Clinical Experience
Case Report 1
Case Summary
Problem List
Treatment Objectives
Treatment Plan
Treatment Sequence
Treatment Results
Case Report 2
Case Summary
Problem List
Treatment Objectives
Treatment Plan
Treatment Sequence
Treatment Results
11 - Zygomatic Miniplate-Supported Molar Distalization
Method Description
Case 11.1
Pretreatment
Extraoral Analysis (Fig. 11.1.1)
Smile Analysis (Fig. 11.1.2)
Intraoral Analysis (see Fig. 11.1.2)
Functional Analysis
Diagnosis and Case Summary
Problem List
Treatment Objectives
Treatment Options
Treatment Sequence
Final Results
What Was the Cause of This Asymmetrical Malocclusion in This Patient?
Case 11.2
Pretreatment
Extraoral Analysis (Fig. 11.2.1)
Smile Analysis (see Fig. 11.2.1)
Intraoral Analysis (see Fig. 11.2.1)
Functional Analysis
Diagnosis and Case Summary
Problem List
Treatment Objectives
Treatment Options
Treatment Sequence and Biomechanical Plan
Treatment Sequence
Final Results
Conclusions
VI -
Buccal TADs and Extra-Alveolar TADs
12 -
Managing Complex Orthodontic Tooth Movement With C-Tube Miniplates
Introduction
Methods
Clinical Report
Case 1
Case 2
Case 3
Discussion
Conclusion
13 - Application of Buccal TADs for Distalization of Teeth
Methods of Distalizing Molars
Distalizing Molars by TADs
Biomechanics in Distalizing Molars With Buccal TADs
Treatment Outcome of Distalization by TADs
Stability of Distalization by TADs
Case 1. Distalization of Maxillary Molars in Skeletal II, Angle Class II Case
Diagnosis
Treatment Plan
Treatment Progress
Treatment Results
Retention
Superimposition
Case 2: Distalization of Mandibular Molars in Skeletal III, Angle Class III Case
Diagnosis
Treatment Plan
Treatment Progress
Treatment Results
Retention
Superimposition
Case 3: Distalization of Maxillary and Mandibular Molars in Skeletal II, Angle Class II Bimaxillary Case
Diagnosis
Treatment Plan
Treatment Progress
Treatment Results
Retention
Superimposition
14 - Application of Extra-Alveolar Mini-Implants to Manage Various Complex Tooth Movements
Introduction
Indications
Characteristics of Mini-Implants
Placement Technique
Placement in the Infrazygomatic Crest
Placement in the Buccal Shelf
Placement Technique
Placement in the Buccal Shelf Region
Magnitude of the Force Applied
Benefits
Precautions
Final Considerations
VII -
Management of Multidisciplinary and Complex Problems
15 -
Management of Skeletal Openbites With TADs
Biomechanics of Molar Intrusion in Skeletal Openbites
Case Report One
Vertical Control With Palatal TADs in the Growing Patient
Case Report Two
Mandibular Molar Intrusion in Openbite Correction
Correction of Anterior Openbites Through Incisor Extrusion With TADs
Case Report Three
Conclusion
16 - Orthognathic Camouflage With TADs for Improving Facial Profile in Class III Malocclusion
Bimaxillary Extrusion Without TADs
Preparation
Placement of Bite Raisers to Backward Rotate Mandible
Extrusion of Anterior Teeth to Close Anterior Openbite
Extrusion of Posterior Teeth
(Continued on next page)
(Continued on next page)
(Continued on next page)
(Continued on next page)
Single-Dentition Extrusion With TADs in Mandible
Insertion of TADs
(Continued on next page)
(Continued on next page)
(Continued on next page)
Placement of Bite Raisers and Extrusion of Upper Anterior Teeth
Extrusion of Posterior Teeth
Single-Dentition Extrusion With TADs in Maxilla
Insertion of TADs
Maxillary Vertical Development in Class III Patients
Comparisons and Indications of Bimaxillary Extrusion and Single-Dentition Extrusion
The Stability of Orthodontic Extrusion
17 - Management of Multidisciplinary Patients With TADs
Temporary Anchorage Devices (TADs) for Space Development for Implant in Congenitally Missing Lateral Incisor
Case Report One
TADs for Preprosthetic Space Appropriation
Case Report Two
Endosseous Dental Implants for Anchorage in Patients With Missing Posterior Teeth
Case Report Three
Ridge Mini-implants for Orthodontic Anchorage
Case Report Four
TADs in Patients With Compromised Maxillary Incisors
Skeletal Anchorage in Orthognathic Surgery
Case Report Five
Mini-implants in Vertical Alveolar Ridge Development
Case Report Six
Conclusion
18 - Second Molar Protraction and Third Molar Uprighting
Introduction
Third Molar Changes With Second Molar Protraction
Cases of Horizontally Impacted Third Molars
Case One
Case Two
Case Three
Conclusion
19 - Class II Nonextraction Treatment With MGBM System and Dual Distal System
Phase 1: Upper Molar Distalization
Clinical Tips for Phase 1
Phase 2: Retraction of the Upper Premolars and Canines
Clinical Tips for Phase 2
Phase 3: Incisors Retraction
Clinical Tips for Phase 3
Dual Distal System
Conclusion
20 - Anchorage of TADs Using Aligner Orthodontics Treatment for Lower Molars Distalization
Introduction
Case One
Treatment Goals
Treatment Alternatives
Treatment Progression
Treatment Results
Case Two
Treatment Progression
Treatment Results
Discussion
Conclusion
Index
A
B
C
D
E
F
G
H
I
L
M
N
O
P
Q
R
S
T
U
V
W
Z
IBC

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Temporary Anchorage Devices in Orthodontics ..

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Temporary Anchorage Devices in Orthodontics SECOND EDITION

Ravindra Nanda, BDS, MDS, PhD Professor Emeritus Division of Orthodontics Department of Craniofacial Sciences School of Dental Medicine University of Connecticut Farmington, Connecticut, USA

Flavio Uribe, DDS, MDentSc Burstone Professor of Orthodontics Graduate Program Director Division of Orthodontics Department of Craniofacial Sciences School of Dental Medicine University of Connecticut Farmington, Connecticut, USA

Sumit Yadav, DDS, MDS, PhD Associate Professor Division of Orthodontics Department of Craniofacial Sciences School of Dental Medicine University of Connecticut Farmington, Connecticut, USA

© 2021, Elsevier. All rights reserved. First edition 2009 No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations, such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein).

Notices Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds or experiments described herein. Because of rapid advances in the medical sciences, in p ­ articular, independent verification of diagnoses and drug dosages should be made. To the fullest extent of the law, no responsibility is assumed by Elsevier, authors, editors or contributors for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. ISBN: 978-0-323-60933-3

Content Strategist: Alexandra Mortimer Content Development Specialist: Kim Benson Project Manager: Beula Christopher Design: Patrick Ferguson Marketing Manager: Allison Kieffer Printed in China Last digit is the print number: 9 8 7 6 5 4 3 2 1

Contents

Preface, vii

Part IV:  Skeletal Plates

Contributors, ix

8 Nonextraction Treatment of Bimaxillary Anterior Crowding With Bioefficient Skeletal Anchorage, 89

Acknowledgements, xiii Dedication, xv

Part I: Biology and Biomechanics of Skeletal Anchorage 1 Biomechanics Principles in Mini-Implant Driven Orthodontics, 3 Madhur Upadhyay and Ravindra Nanda

Part II:  Diagnosis and Treatment Planning 2 Three-Dimensional Evaluation of Bone Sites for Mini-Implant Placement, 23 Aditya Tadinada and Sumit Yadav

3 Success Rates and Risk Factors Associated With Skeletal Anchorage, 29 Sumit Yadav and Ravindra Nanda

Junji Sugawara, Satoshi Yamada, So Yokota and Hiroshi Nagasaka

9 Managing Complex Orthodontic Problems With Skeletal Anchorage, 109 Mithran Goonewardene, Brent Allan and Bradley Shepherd

Part V:  Zygomatic Implants 10 Zygomatic Miniplate-Supported Openbite Treatment: An Alternative Method to Orthognathic Surgery, 149 Nejat Erverdi and Çağla Şar

11 Zygomatic Miniplate-Supported Molar Distalization, 165 Nejat Erverdi and Nor Shahab

Part III:  Palatal Implants

Part VI: Buccal TADs and Extra-Alveolar TADs

4 Space Closure for Missing Upper Lateral ­Incisors, 35

12 Managing Complex Orthodontic Tooth Movement With C-Tube Miniplates, 183

Bjöern Ludwig and Bettina Glasl

5 Predictable Management of Molar ThreeDimensional Control with i-station, 43 Yasuhiro Itsuki

6 MAPA: The Three-Dimensional Mini-Implants-­ Assisted Palatal Appliances and One-Visit ­Protocol, 61 B. Giuliano Maino, Luca Lombardo, Giovanna Maino, Emanuele Paoletto and Giuseppe Siciliani

7 Asymmetric Noncompliance Upper Molar ­Distalization in Aligner Treatment Using ­Palatal TADs and the Beneslider, 71 Benedict Wilmes and Sivabalan Vasudavan

Seong-Hun Kim, Kyu-Rhim Chung and Gerald Nelson

13 Application of Buccal TADs for Distalization of Teeth, 195 Toru Deguchi and Keiichiro Watanabe

14 Application of Extra-Alveolar Mini-Implants to Manage Various Complex Tooth Movements, 209 Marcio Rodrigues de Almeida

Part VII: Management of Multidisciplinary and Complex Problems 15 Management of Skeletal Openbites With TADs, 223 Flavio Uribe and Ravindra Nanda

v

vi

Contents

16 Orthognathic Camouflage With TADs for Improving Facial Profile in Class III Malocclusion, 243 Eric JW. Liou

17 Management of Multidisciplinary Patients With TADs, 263 Flavio Uribe and Ravindra Nanda

18 Second Molar Protraction and Third Molar Uprighting, 283 Un-Bong Baik

19 Class II Nonextraction Treatment With MGBM System and Dual Distal System, 295 B. Giuliano Maino, Giovanna Maino, Luca Lombardo, John Bednar and Giuseppe Siciliani

20 Anchorage of TADs Using Aligner Orthodontics Treatment for Lower Molars Distalization, 305 Kenji Ojima, Junji Sugawara and Ravindra Nanda

Index, 321

Preface

The new millennium brought about a new era in orthodontics with the advent of temporary anchorage devices (TADs). The realm of possibilities to correct malocclusions that in the past were only treatable by means of orthognathic surgery was made available in a cost-effective manner through the insertion of small screws and miniplates during orthodontic treatment. Clinicians quickly became interested in adopting this new approach in their patients, and precise indications for the use of skeletal anchorage started to shape up. The first edition of Temporary Anchorage Devices in Orthodontics, which was compiled in the early days of skeletal anchorage, was a very timely book that introduced many aspects of this new approach. The chapters of this first book described the use of miniplates and screws with emphasis on the multiple locations of placement in the maxilla and mandible and a myriad of screw systems and appliances. The biomechanics involved with new skeletal anchorage orthodontic adjuncts was described in detail, with many case reports illustrating the expanded possibilities to correct complex malocclusions and enhance smile esthetics. Approximately a decade has transpired since the first edition, and significant refinements to the techniques and appliances have been developed. In this second edition, we wanted to highlight these advances described by multiple authors that had been at the forefront of skeletal anchorage era since the early days. The first chapters in this edition review the biology and interaction of the titanium hardware and bone and the basic biomechanic principles that apply when using skeletal anchorage. The application of space closure, distalization, and overall molar control form palatal appliances is described in depth with different approaches. Later in the book, the versatility of miniplates and infrazygomatic mini-implants is presented by multiple authors managing cases of significant complexity. Finally,

the management with skeletal anchorage of anteroposterior and vertical problems, such as the management of the Class III malocclusion, second molar protraction, anterior openbite correction, and the mechanical advantages of TADs in multidisciplinary patients, are described. A very interesting development in skeletal anchorage presented in this new edition is the integration of threedimensional (3D) technologies for the placement of miniimplants and the fabrication of TAD-supported appliances. With the advent of 3D-printing, precise palatal appliances are now available as described in this book with the MAPA appliance. Overall, this new approach sets a trend where the application of 3D-printing facilitates the insertion of miniimplants and the delivery of appliances in a single visit in a very precise and predictable manner. Another novel and interesting approach is the combination of clear aligner therapy with skeletal anchorage. Clear aligners are increasingly becoming the elected orthodontic appliance by adults, and a tightly coupled synergy with TADs for the treatment of more complex malocclusions in patients demanding nonvisible appliances is described in this book. We want to thank all the contributors who have invested time and effort to advance our knowledge regarding skeletal anchorage. We also appreciate the contributions of numerous individuals who are not part of this book but who have influenced all of us with their scientific publications. We hope you will enjoy reading it, and various methods of skeletal anchorage usage shown will help in efficient treatment of patients. Ravindra Nanda Flavio Uribe Sumit Yadav Farmington, Connecticut, USA

vii

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Contributors

The editor(s) would like to acknowledge and offer grateful thanks for the input of all previous editions’ contributors, without whom this new edition would not have been possible. Brent Allan, BDS, MDSc, FRACDS, FFD RCS (Ireland), FDS RCS (England) Oral and Maxillofacial Surgeon Department of Orthodontics The University of Western Australia Nedlands, Western Australia, Australia; Private Practice Leederville, Western Australia, Australia Marcio Rodrigues de Almeida, DDS, MSc, PhD Unopar Orthodontics UNOPAR Londrina, Parana, Brazil Un-bong Baik, DDS, MS, PhD Second Molar Protraction and Third Molar Uprighting Head Smile-with Orthodontic Clinic Seoul, Republic Of Korea John Robert Bednar, BA, DMD Assistant Clinical Professor in Orthodontics (Ret) Department of Orthodontic Boston University Henry M. Goldman School of Dental Medicine Boston, Massachusetts, USA Kyu-Rhim Chung, DMD, MSD, PhD Clinical Professor Department of Orthodontics Graduate School, Kyung Hee University Seoul, Republic of Korea Toru Deguchi, DDS, MSD, PhD Associate Professor Orthodontics The Ohio State University Columbus, Ohio, USA

Nejat Erverdi, DDS, PhD Professor Faculty of Dentistry Department of Orthodontics Okan University Istanbul, Turkey Bettina Glasl, MD Orthodotics Praxis Dr. Ludwig Dr. Glasl Traben-Trarbach, Germany Mithran Goonewardene, BDSc, MMedSc Orthodontics The University of Western Australia Nedlands, Western Australia, Australia Yasuhiro Itsuki, PhD, DDS Private Practice Jingumae Orthodontics Tokyo, Japan Seong-Hun Kim, DMD, MSD, PhD Professor and Head Department of Orthodontics Graduate School, Kyung Hee University Seoul, Republic Of Korea Eric J.W. Liou, DDS, MS Associate Professor Department of Craniofacial Orthodontics Chang Gung Memorial Hospital Taipei, Taiwan Luca Lombardo, DDS Associate Professor Postgraduate School of Orthodontics Ferrara University Ferrara, Italy Björn Ludwig, PhD Orthodontics Praxis Dr. Ludwig Dr. Glasl Traben-Trarbach, Germany

ix

Contributors

x

Giovanna Maino, DMD Dentistry Adjunct Professor Postgraduate School of Orthodontics Ferrara University; Private practice Vicenza, Italy

Bradley Shepherd, BDSc, MDSc, FRACDS Prosthodontist Department of Prosthodontics The University of Western Australia Nedlands, Western Australia, Australia; Private Practice Leederville, Western Australia, Australia

B. Giuliano Maino, MD, DDS Postgraduate School of Orthodontics Ferrara University and Insubria University; Private Practice Vicenza, Italy

Giuseppe Siciliani, DDS Chairman Postgraduate School of Orthodontics Ferrara University Ferrara, Italy

Hiroshi Nagasaka, DDS, PhD Chief Department of Oral and Maxillo-facial Surgery Sendai Aoba Clinic Sendai, Japan

Junji Sugawara, DDS, DDSc Sendai Aoba Clinic Orthodontics Dentistry Sendai, Japan

Ravindra Nanda, BDS, MDS, PhD Professor Emeritus Division of Orthodontics Department of Craniofacial Sciences School of Dental Medicine University of Connecticut Farmington, Connecticut, USA

Aditya Tadinada, DDS, MS, MDS Director of Student Research, Program Director of the Residency Program Oral and Maxillofacial Radiology UCONN School of Dental Medicine Farmington, Connecticut, USA

Gerald Nelson, DDS Clinical Professor Orofacial Sciences UCSF School of Dentistry San Francisco, California, USA Kenji Ojima, DDS, MDSc Smile Innovation Orthodontics Hongo Bunkyo-ku Tokyo, Japan Emanuele Paoletto, SDT Certified Orthodontic Technician (COT) Teacher Postgraduate School of Orthodontics Ferrara University Ferrara, Italy; Private practice Thiene, Italy Çağla Şar, DDS, PhD Associate Professor Private Practice Istanbul, Turkey Nor Shahab, MSc Orthodontics Faculty of Dentistry Department of Orthodontics Istanbul Aydın University Istanbul, Turkey

Madhur Upadhyay, BDS, MDS, MDentSc Associate Professor Orthodontics UCONN Health Farmington, Connecticut, USA Flavio Uribe, DDS, MDentSc Burstone Professor of Orthodontics Graduate Program Director Division of Orthodontics Department of Craniofacial Sciences School of Dental Medicine University of Connecticut Farmington, Connecticut, USA Sivabalan Vasudavan, BDSc, MDSc, MPH, M Orth, RCS, FDSRCS, MRACDS (Orth) Certified Craniofacial and Cleft Lip/Palate Orthodontics Specialist Orthodontist Orthodontics on Berrigan Orthodontics on St Quentin Perth, Western Australia, Australia

Contributors

Keiichiro Watanabe, DDS, PhD Postdoctoral Researcher Orthodontics The Ohio State University Columbus, Ohio, USA; Assistant Professor Orthodontics and Dentofacial Orthopedics Tokushima University Graduate School Tokushima, Japan Benedict Wilmes, DDS, DMD, PhD Professor Department of Orthodontics University of Duesseldorf Duesseldorf, Germany

Sumit Yadav, DDS, DMD, PhD Associate Professor Division of Orthodontics Department of Craniofacial Sciences School of Dental Medicine University of Connecticut Farmington, Connecticut, USA Satoshi Yamada, DDS, PhD Chief Department of Orthodontics Sendai Aoba Clinic Sendai, Japan So Yokota, DDS, PhD Sendai Aoba Clinic Department of Oral and Maxillo-facial Surgery Sendai Aoba Clinic Sendai, Japan

xi

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Acknowledgements

We would like to acknowledge all the residents and faculty at UConn Health that contributed to their dedicated care of the patients illustrated in our chapters.

xiii

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We dedicate this book to our parents for all that we have and all that we do.

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PART I

Biology and Biomechanics of Skeletal Anchorage 1. Biomechanics Principles in Mini-Implant Driven Orthodontics Madhur Upadhyay and Ravindra Nanda

1 1

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1

Biomechanics Principles in Mini-Implant Driven Orthodontics MADHUR UPADHYAY, RAVINDRA NANDA

Introduction The physical concepts that form the foundation of orthodontic mechanics are the key in understanding how orthodontic appliances work and are critical in designing the treatment methodologies and appliances that carry out these plans. Mechanics can be defined as a branch of physics concerned with the mechanical aspects of any system. This can be divided into two categories:   

Statics, the study of factors associated with nonmoving (rigid) systems, and Dynamics, the study of factors associated with systems in motion: a moving car, plane etc. When the knowledge and methods of mechanics are applied to the structure and function of living systems (biology) like, for example, a tooth together with its surrounding oral architecture, it is called biomechanics. It is our belief that the study of biomechanics of tooth movement can help researchers and clinicians optimize their force systems applied on teeth to get better responses at the clinical, tissue, cellular, or molecular level of tooth movement.   

 Approaches for Studying Tooth Movement Two approaches are used for studying the biological and mechanical aspects of tooth movement—a quantitative approach and a qualitative approach. The quantitative approach involves describing movement of teeth or the associated skeletal structures in numerical terms. We all are familiar with terms like 3 millimeters of canine retraction, or 15 degrees of incisor flaring. However merely describing tooth movement quantitatively does not describe the complete nature of the movement. It is also important to understand the type or nature of tooth movement that has occurred. A qualitative approach describes movement in nonnumerical terms (i.e., without measuring or counting

any parts of the performance). This approach is often followed at the clinical level or inferred from x-rays and/or stone models like tipping, translation, etc. Both qualitative and quantitative analyses provide valuable information about a performance; however, a qualitative assessment is the predominant method used by orthodontists in analyzing tooth movement. The impressions gained from a qualitative analysis may be substantiated with quantitative data, and many hypotheses for research projects are formulated in such a manner. 

Basic Mechanical Concepts Force The role of force in everyday life is a familiar one. Indeed, it seems almost superfluous to try to define such a self-evident concept as force. To put it in a simple way, force can be thought of as a measure of the push or pull on an object. However, the study of mechanics of tooth movement demands a precise definition of force. A force is something that causes or tends to cause a change in motion or shape of an object or body. In other words, force causes an object to accelerate or decelerate. It is measured in Newton (N), but in orthodontics nearly always force is measured in grams (g). 1 N = 101.9 g (≈ 102 g) (see appendix). Force has four unique properties as shown by graphic representation of a force acting at an angle to a central incisor in Fig. 1.1: • Magnitude: how much force is being applied (e.g., 1 N, 2 N, 5 N). • Direction: the way the force is being applied or its orientation to the object (e.g., forward, upward, backward). • Point of application: where the force is applied on the body or system receiving it (e.g., in the center, at the bottom, at the top). • Line of action/force: the straight line in the direction of force extending through the point of application.  3

4 PA RT I    Biology and Biomechanics of Skeletal Anchorage

Line of action of force

Point of application of force Length = Magnitude of force

Direction of force relative to the horizontal

(-)

θ

(+)

x-axis

• Fig. 1.1  The four properties of an external force applied to a tooth illustrated by an elastic chain applying a retraction (distalizing) force on a maxillary incisor to a mini-implant.

Principle of Transmissibility F1 F2

F3

• Fig. 1.2  The length of the force vector describes the magnitude of the force vector. Example: F1 = 2 N, F2 = 3 N, F3 = 1 N.

Force Diagrams and Vectors Physical properties (such as distance, weight, temperature, and force) are treated mathematically as either scalars or vectors. Scalars, including temperature and weight, do not have a direction and are completely described by their magnitude. Vectors, on the other hand, have both magnitude and direction. Forces may be represented by vectors. To a move a tooth predictably, a force needs to be applied with an optimal magnitude, in the desired direction, and at the correct point on the tooth. Changing any property of the force will affect the quality of tooth displacement. A force may be represented on paper by an arrow. Each of its four properties may be represented by the arrow whose length is drawn to a scale selected to represent the magnitude of the force—for example, 1 cm = 1 N or 2 cm = 2 N, etc. (Fig. 1.2). The arrow is drawn to point in the direction in which the force is applied, and the tail of the arrow is placed at the force’s point of application. The line of action of the force may be imagined as continuing indefinitely in both directions (head and tail end), although the actual arrow, if drawn to scale, must remain of a given length. A graphic representation of a force of 1 N acting at an angle of 30 degrees to a central incisor is shown in Fig. 1.1.

This concept is very important for vector mechanics, especially in understanding equilibrium and equivalent force systems as we will see later. It implies that a force acting on a rigid body results in the same behavior regardless of the point of application of the force vector as long as the force is applied along the same line of action. 

The Effect of Two or More Forces on a System: Vector Addition Teeth are often acted on by more than one force. The net effect or the resultant of multiple forces acting on a system, in this case teeth, can then be determined by combining all the force vectors. This process of combining all the forces may be found by a geometric rule called vector addition, or vector composition. We place the vectors head to tail, maintaining their magnitudes and directions, and the resultant is the vector drawn from the tail of the first vector to the head of the final vector. Vector addition can be accomplished graphically by drawing diagrams to scale and measuring or by using trigonometry. Fig. 1.3 shows how the two forces are visualized as two sides of a parallelogram and how the opposite sides are then drawn to form the whole parallelogram. The resultant force, R, is represented by the diagonal that is drawn from the corner of the parallelogram formed by the tails of the two force vectors. 

The Directional Effects of Force: Vector Resolution Often an occasion arises in which the observed movement of a system or single force acting on a system is to be analyzed in terms of identifying its component directions. In such cases, the single vector quantity given is divided into two components: a horizontal component and a vertical component. The directions of these components are relative to some reference frame, such as the occlusal plane or the Frankfort horizontal plane (FHP), or to some axis in the system itself. The horizontal and vertical components are usually perpendicular to each other. Such a process maybe thought of as the reverse of the process of vector

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FR

FE R=

FR+

FE

FE FR

• Fig. 1.3  Illustration showing the law of vector addition by the parallelogram method. Here, FR can be thought of as a retractive force on the incisor and FE as a force from a Class II elastics. The net effect of the two forces is represented by the resultant R.

Vertical component of the total force(FV)

F

F

Horizontal component of the total force (FH)

B

A

FV θ FH

C • Fig. 1.4  The process of vector resolution.

composition. The operation is called vector resolution and is the method for determining two component vectors that form the one vector given initially. For example, a mini-implant as shown in Fig. 1.4A is being used for retraction of anterior teeth. It may be useful to resolve this force into the components that are parallel and perpendicular to the occlusal plane, to determine the magnitude of force in each of these directions. Resolution

consists of these steps (Fig. 1.4B–C): (1) draw the vector given initially to a selected scale; (2) from the tail of the vector, draw lines representing the desired directions of the two perpendicular components; (3) from the head of the vector, draw lines parallel to each of the two direction lines so that a rectangle is formed. Note that the new parallel lines constructed have the same magnitude and direction as the corresponding lines on the opposite side of the rectangle.

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It is important to note that if it is desirable to estimate the magnitude of the components, then simple trigonometric rules can be invoked to do so. The sine and cosine are in particular very useful in finding the horizontal and vertical components of the force vector. In this case if, for example, the horizontal component of magnitude FH makes an angle θ with the force (F), we can derive the components using the definitions of sine and cosine:   

Horizontal component (FH): FH/F = cos θ; FH = F cos θ Vertical component (FV): FV/F = sin θ; FV = F sin θ    With a little practice, it is easy to get the component directly as a product, skipping the step involving the proportion. Think of sin θ and cos θ as fractions that are used to calculate the sides of a right triangle when the hypotenuse is known. The side is always less than the hypotenuse and the sine and cosine are always less than one. To get the side opposite the angle, simply multiply the hypotenuse by the sine of the angle. To get the side adjacent to the angle, multiply the hypotenuse by the cosine of the angle. 

Center of Resistance, Center of Gravity, and Center of Mass The center of mass of a system may be thought of as that point at which all the body’s mass seems to be concentrated (i.e., if a force is applied through this point, the system or body will move in a straight line). On similar lines recall that the earth exerts a force on each segment of a system in direct proportion to each segment’s mass. The total effect of the force of gravity on a whole body, or system, is as if the force of gravity were concentrated at a single point called the center of gravity. Again, if a force is applied through this point, it will cause the body to move in a straight line without any rotation. The difference between the center of mass and center of gravity is that the system in question in the latter is a ‘restrained system’ (restrained by the force of gravity). Teeth are also a part of a restrained system. Besides gravity, they are more dominantly restrained by periodontal structures that are not uniform (involving the root but not the crown) around the tooth. Therefore the center of mass or the center of gravity will not yield a straight line motion if a force is applied through it because the surrounding structures and their composition alter this point. A new point analogous to the center of gravity is required to yield a straight-line motion; this is called the center of resistance (CRES) of the tooth (Fig. 1.5). The CRES can also be defined by its relationship to the force: a force for which the line of action passes through the CRES producing a movement of pure translation. It must be noted that, for a given tooth, this movement may be mesiodistal or vestibulolingual, intrusive or extrusive. The position of the CRES is directly dependent on what may be called the “clinical root” of the tooth. This concept considers the root volume, including the periodontal bone (i.e., the distance between the alveolar crest and the apex), incrementing this value with the thickness (i.e., the surface) of the root.1

Center of resistance (CRES) Center of mass or center of gravity(CG)

• Fig. 1.5  The center of resistance (CRES) of a tooth is usually located

slightly apical to the center of gravity (CG). The periodontal structures surrounding the tooth root cause this apical migration of the CRES.

Thus the position of the CRES is also a function of the nature of the periodontal structures, and the density of the alveolar bone and the elasticity of the desmodontal structures that are strongly related to the patient’s age.2–4 These considerations implore us to speak of the “CRES associated with the tooth,” rather than of “the CRES of the tooth.” 

Moment (Torque) When an external force acts on a body at its center of gravity (CG), it causes that body to move in a linear path. Such a type of force with its line of action through the CG or CRES of a body is called a centric force. On similar lines, eccentric forces (off-center) act away from the CRES of a body. What kind of effect will these forces have? Besides causing the body to move in a linear path, it will have a turning effect on the body called torque, or in other words the force will also impart a “moment” on the body. The off-axis distance of the force’s line of action is called the force arm (or sometimes the moment arm, lever arm, or torque arm). The greater this distance, the greater the torque produced by the force. The specifications of the force arm are critical. The force arm is the shortest distance from the axis of rotation to the line of action of force. Invariably the shortest distance is always the length of the line that is perpendicular (90 degrees) to the force’s line of action (d⏊). The symbol “⏊” designates perpendicular. Force arm is critical in determining the amount of moment acting on the system. The amount of moment (M) acting to rotate a system is found by multiplying the magnitude of the applied force (F) by the force arm distance (d⏊): M = F(d⏊), where F is measured in Newton and d⏊ in millimeter (Fig. 1.6A). Therefore the unit for moment as used in orthodontics is Newton millimeter (Nmm). As mentioned previously, often for force Newton is replaced

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M

M

Tp

Tp F

F

A

B

• Fig. 1.6  (A) The moment of a force is equal to the magnitude of the force multiplied by the perpendicular distance from its line of action to the center of resistance. (B) The direction of the moment of a force can be determined by continuing the line of action around the center of resistance.

F

F

D

Mc

mc F

F

A

d

B

• Fig. 1.7  (A) The moment created by a couple is always around the center of resistance (CRES) or center

of gravity (CG) (MC = F × D). (B) No matter where the pair of force are applied, the couple created will always act around the CRES or CG. As the distance between the two forces decreases (d r > i, (F = total force, i = intrusive component and r = retractive component). Also the moment created by the implant will be significantly less than that created by conventional mechanics (force application with implants is closer to the center of resistance (CRES) and M = F × distance to the CRES). Note: with the conventional approach, there is no intrusive force generated.

A

6-7 mm

B

2-3 mm

3-4 mm

• Fig. 1.17  Anterior teeth that have to be distalized a greater distance (A) and will be automatically predisposed to greater degrees of tipping than those requiring less distalization (B). Note: the molar represents the posterior segment while the incisor represents the anterior teeth.

MF

MC

F

• Fig. 1.18  Basic mechanics of tooth movement. Here, F = retraction force, MF = moment caused by the force, MC = counterbalancing moment.

occlusal and buccal to the CRES of the units experiencing the force. This generates moments (moment caused by force, or MF as described previously), which cause tipping and rotation of the teeth in the direction of the applied force.13,14 Here, it is easy to see that by simply controlling the MF, different types of tooth movement can be achieved (e.g., tipping, translation, etc.). But how can we manipulate the MF? In the entire orthodontic spectrum, there are only two broad mechanical pathways to achieve this: 1. Changing the line of force application (or reducing the magnitude of MF) 2. Counterbalancing the MF (adding another moment in the opposite direction). Let us consider each of these options.

14 PA RT I    Biology and Biomechanics of Skeletal Anchorage

10-11 mm 8-9 mm 6.5-7.5 mm

3-5 mm

0 mm

• Fig. 1.19  Altering the line of force application can change the center of rotation and/or the type of tooth movement. Orange: uncontrolled tipping, Blue: controlled tipping, Pink: translation, Purple: root movement, Green: root movement with crown moving forward. Red dot: center of resistance, other dots: center of rotations corresponding with the line of force.

1. Changing the Line of Force Application A simple way of accomplishing this is to apply the force closer to the CRES of the anterior teeth. A rigid attachment, often called a power arm, can be attached to the bracket on the crown of the tooth or on the wire itself. Force can then be applied to this power arm. In this way, the line of force is moved to a different location, thereby altering its distance from the CRES. This also causes a change in the moment of the force. For example, if the power arm can be made long and rigid to extend to the CRES of the tooth, the moment arm (MF) can be entirely eliminated, as the applied force will pass through the CRES (moment = applied force × distance from the CRES). Based on theoretical calculations, in  vitro and in  vivo experiments, and with certain assumptions, we have come up with a model (Fig. 1.19) describing various types of tooth movement depending on the line of force application,15,16–20 and by the location of the tooth’s CROT as a rotation axis. The figure shows the CROT for every level of force. This model only applies for maxillary incisors and measures only the initial tooth movement. This approach is easier to execute with skeletal anchorage because MIs are usually placed between the roots of the molar and premolar. Here, the height of both the power arm and MI can be varied depending on the line of force required. It works well for both large segments of teeth or individual teeth (Fig. 1.20). However, for movements requiring greater degrees of control, such as translation or root movement, this method possesses certain problems. The “long” arms can be a source of irritation to the patient, by extending high into the vestibule and/or impinging on the gingiva and cheeks. In addition, the arms are sometimes not rigid enough and can undergo some degree of flexion under the applied force. Therefore retraction of incisors is often performed without the use of a power arm. However,

without the power arm, the ability to reduce the MF is also lost. In this situation, how do we control the tooth movement? How do we bring about the desired tooth movement, which can be so easily achieved with “power arms?” 2. Counterbalancing the MF (Sliding Mechanics With Mini-Implants) Force system through time. The en masse retraction described at the beginning of the chapter outlined the forces and moment during the initial stages of space closure, i.e., it represented only the beginning phase of retraction. What happens later? We are well aware of the fact that space closure is a dynamic process, and things change as teeth move. Considerable research in this area has provided us with a more detailed representation of the incisor movement and its effect on the entire dentition.11–18 Based on the evidence gathered from this pool of research, we have further refined the mechanic model of incisor retraction with MIs. Essentially, incisor retraction can be divided into four phases (please refer to Fig. 1.6 for each phase).   

Phase I. This is the initiation of incisor retraction. A single force (F) is applied in an upward and backward/distal direction (Fig. 1.21A). This force produces a moment (MF) acting at the CRES of the incisor segment, causing it to tip as it is being distalized. Since there is some degree of play between the archwire and the bracket slot at this stage, the tooth is free to tip in the mesiodistal direction in an uncontrolled manner, creating a CROT slightly apical to the CRES13,14 (see Fig. 1.19). This can also be referred to as the unsteady state of incisor retraction, characterized by uncontrolled tipping. Here, it is easy to see that the greater the play, the more will be the tipping, or in other words, the smaller the size of the archwire, the greater will be the tipping. Phase II. The incisor is now tipped to the extent that the aforementioned clearance (or play) between the bracket

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A

B • Fig. 1.20  Power arm–based space closure. (A) En masse retraction of anterior teeth shows controlled tipping. (B) Translation of canine.

slot and the wire is eliminated. The sketch in Fig. 1.21B depicts the incisors somewhat later in time relative to Fig. 1.21A. Archwire–bracket slot contact now exists. This two-point contact by the archwire creates a moment (MC) in the opposite direction of MF resulting in less tipping of the incisors when compared to phase I. This is the “counterbalancing moment” or “moment caused by a

couple” (MC). As the wire further deflects, MC continues to increase (force a deflection, as we will see later), and the CROT moves apically, creating controlled tipping of the incisors. This can also be called the controlled state of incisor retraction. From this point onward, the movement of the teeth will depend on the nature of the retraction force (i.e., a steady continuous force or a force

16 PA RT I    Biology and Biomechanics of Skeletal Anchorage

• Fig. 1.21  Mechanics of incisor retraction with mini-implants (red dot:

MF F

center of rotation). (A) Phase I (the unsteady state/uncontrolled tipping). The archwire–bracket play allows for uncontrolled tipping of the incisor. Note; because of the play there is no MC (moment caused by a couple) generated. (B) Phase II (the controlled state/controlled tipping). The archwire–bracket play does not exist anymore. There are signs of initial contact between the archwire and the bracket edges giving rise to MC. However still MF >> MC. (C) Phase III (restorative phase/ root uprighting because of decreasing force). There is a decrease in the force levels causing a decrease in MF. Here MF > MC.

A

Mc

MF

F

B

Mc

MF

F

C

Mc

F

D

MF

decreasing with time). This at the clinical level is a very relevant supposition. Phase III (decreasing force). For the space closure to enter this phase, it must be assumed that the distal driving force is undergoing a constant decay through the retraction process. This is often seen with an elastomeric chain or active tiebacks.21–23 As the force decreases, so does the MF; however, because of the angulated bracket and the local bending of the archwire, the MC remains constant. Therefore here MC >> MF (Fig. 1.21C). This results in restoration of the axial inclination of the incisors (uprighting or root correction). This can be called the restorative phase of incisor retraction and can be clinically referred to as the third-order torqueing of the incisors. With the reactivation of the elastomeric chain, the process resumes from Phase I. Phase IV (continuous force or heavy force). Incisor retraction enters this phase if the retraction force is either constant or heavy to begin with. Examples can be: nickel titanium closed coil springs, heavy elastomeric chain, etc. Here, because of the heavy retraction force, MF is always >> MC, therefore there is anterior bending or deflection of the archwire and the tipping of incisors continues (Fig. 1.21D). Clinically, the incisors might appear as “dumped” or retroclined (loss of torque) with deep bite and sometimes accompanied with a lateral open bite with the molars tipped forward because of a similar wire deformation. This deformation is accompanied with an increase in friction and/or binding at the wire bracket interface making tooth movement slow. (Note: It is important to mention here that at any point if MC = MF the incisors would theoretically undergo translation. But this almost never happens, as it is very difficult to maintain such a balance between the moments for any measurable period of time).

Sequela of Phase IV: Distalization Effect of Mini-Implant Assisted Retraction It has been widely reported that MI-assisted retraction of incisors has the potential to distalize the whole arch en masse.7–9,11,12 This can occur primarily in two situations

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  Archwire-Bracket Clearance Angle (Play) for

TABLE Various Archwires When Placed in a 0.022 × 1.1 

0.028–Sq. Inch Bracket

M

i

F

r

•

Fig. 1.22 Biomechanical design for the force system involved after space closure. Retraction of the upper anterior teeth still in progress. Note the increase in the angulation of the total force relative to the occlusal plane. (Here, F >> r ≈ i). Such a mechanical configuration has important implications for vertical control and Class II correction.

that are not necessarily mutually exclusive. At the end of phase IV, as we saw in the previous section, there is increased binding and interlocking of the wire to the bracket. This causes the upward and backward retraction force to be transmitted to the posterior segment through the archwire. The stiffer and thicker the archwire, the more pronounced will be this effect. A similar effect is also seen when the space between the anterior and posterior teeth is completely closed but the retraction force is continued for closing residual anterior spaces. This results in transmission of the total force to the posterior segments through the interdental contacts, producing a distal and intrusive force on the posterior teeth and a moment (M) on the entire arch (Fig. 1.22). These mechanics have often been used to correct Class II molar relationships without extractions.24,25 Distalization with MIs also helps in efficient control of the vertical dimension by preventing the extrusion of the molars (see Fig. 1.22), thereby maintaining the mandibular plane angle and in some situations even resulting in intrusion of the posterior teeth and consequent upward and forward rotation of the mandibular plane.7–9,25 

Mechanical Factors Affecting Incisor Retraction It is evident from the previous discussion that the archwire bracket clearance is a very important factor in determining the type of anterior tooth movement in sliding mechanics. The greater the degree of play between the archwire and the bracket, the greater will be the tipping, as the incisor brackets can rotate in that space, causing the roots to move labially.20 In other words the incisors will undergo a prolonged phase I space closure. Table 1.1 shows the approximate

Wire Size (in inches)

Amount of Play (degrees)

0.016 × 0.022

16–18

0.017 × 0.025

12–14

0.019 × 0.025

6–8

0.021 × 0.025

2–3

values of play between archwires and a 0.022 × 0.028–sq. inch bracket.26–29 Needless to say that a 0.016 × 0.022–sq. inch wire will show more tipping than a 019 × 025–sq. inch wire (Fig. 1.23). Another important mechanical aspect to consider is the flexural rigidity of the archwire, which is critical in regulating the wire deformation. Flexural rigidity (D) is denoted by EI, where E is Young’s modulus of the archwire material, and I is the moment of inertia of the cross-sectional area. Once the tipping of incisors has occurred and there is no wire bracket clearance, the flexural rigidity of the archwire or the archwire deformation under the applied load (retraction force) will largely determine the type of tooth movement.20,30 If the wire undergoes elastic deformation, the incisors will keep on tipping in spite of the “zero” clearance between the archwire and bracket. The amount of archwire deformation can be estimated depending on both the flexural rigidity of the archwire and net force acting on the incisors. As a rule, smaller-size wires and less stiff wires show increased flexion when subjected to retraction forces.25 Therefore it is advisable to carry out “en masse” space closure with rigid stainless steel archwires as opposed to the more flexible nickel-titanium based archwires. The mechanical factors explained in the preceding section can be elegantly described by an equation from beam mechanics30–32: 3

Δ= FL K.D

Here, Δ is the amount of deflection of the archwire under the applied load F from its original position (as shown in Fig. 1.21C–D), L is the length of the archwire between the two attachments (here it can be assumed between the molar and the incisors), D is the flexural rigidity described earlier, and K is a constant that reflects the stiffness of the beam and is dependent on the brackets supporting it. Please note, this equation will be more suitable to describe tooth movement that mimics a “three-point bending test” or a cantilever beam with the load concentrated at the free end.

The “Hybrid Model” With Mini-Implant Anchorage The hybrid approach combines the two methods of controlling anterior teeth retraction, that is, applying a

18 PA RT I    Biology and Biomechanics of Skeletal Anchorage

019 x 025 -inch

016 x 022 -inch

• Fig. 1.23  The amount of play between the bracket and archwire depends on the size of the archwire.

Post

Pre

• Fig. 1.24  Clinical application of power arm soldered on 0.019 × 0.025 SS archwires for space closure. The blue arrow shows the root movement obtained.

A B • Fig. 1.25  Sliding mechanics with power arm. (A) Moment (blue) caused by retraction force. (B) Moment (red) generated by the torsional effect of the archwire.

CHAPTER 1  Biomechanics Principles in Mini-Implant Driven Orthodontics

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• Fig. 1.26  A clinical example of power arm–based space closure.

counterbalancing moment and changing the line of force application (Fig. 1.24). In this approach, a power arm is soldered onto the archwire mesial to the canine, bilaterally. In this way, the clinician can choose the line of force application from the CRES through the power arm to the MI. In addition, the retraction force from the power arm causes the upward deformation and the torsion of the anterior segment of the archwire. This torsion of the archwire produces a couple that works as anti-tipping moment to the anterior teeth (Figs. 1.25 and 1.26). In other words, this couple has a lingual root tipping effect on the incisors. Longer power arms are more effective in minimizing archwire deflection than are shorter ones, as the MF is reduced. Also thicker wires will provide better torsional control than lighter wires will, as we saw in the preceding section. 

Conclusions MIs in the present day and age are one of the best modalities to maintain “absolute” anchorage. However, they by themselves do not guarantee a well-defined and controlled movement of teeth without side effects. Line of force application, amount of force, force decay/constancy, archwire–bracket play, and archwire deflection (regulated primarily by the archwire properties) are critical factors for controlling incisor retraction with MI-supported anchorage. It is imperative to regulate these factors to minimize archwire deflection for unwanted side effects like loss of torque control on the incisors, resulting deep bite and/or lateral open bite caused by tipping of the anterior and posterior teeth, increase in friction/binding forces leading to stagnant or slowing of tooth movement, etc.

References 1. Burstone CJ, Pryputniewicz RJ: Holographic determination of centers of rotation produced by orthodontic forces, Am J Orthod 77:396, 1980. 2. Davidian EJ: Use of a computer model to study the force distribution on the root of the maxillary central incisor, Am J Orthod 59:581–588, 1971. 3. Hay GE: The equilibrium of a thin compressible membrane, Can J Res 17:106–121, 1939. 4. Yettram AL, Wright KWJ, Houston WJB: Center of rotation of a maxillary central incisor under orthodontic loading, Br J Orthod 4:23–27, 1977. 5. Christiansen RL, Burstone CJ: Centers of rotation within the periodontal space, Am J Orthod 55:351–369, 1969. 6. Smith RJ, Burstone CJ: Mechanics of tooth movement, Am J Orthod 85(4):294–307, 1984. 7. Upadhyay M, Yadav S, Nagaraj K, Patil S: Treatment effects of mini-implants for en-masse retraction of anterior teeth in bialveolar dental protrusion patients: a randomized controlled trial, Am J Orthod Dentofacial Orthop 134:18–29. e1, 2008. 8. Upadhyay M, Yadav S, Patil S: Mini-implant anchorage for enmasse retraction of maxillary anterior teeth: a clinical cephalometric study, Am J Orthod Dentofacial Orthop 134:803–810, 2008. 9. Upadhyay M, Yadav S, Nanda R: Vertical-dimension control during enmasse retraction with mini-implant anchorage, Am J Orthod Dentofacial Orthop 138:96–108, 2010. 10. Upadhyay M, Nanda R: Biomechanics in orthodontics. In Nanda R, editor: Esthetics and biomechanics in orthodontics, ed 2, Philadelphia, PA, 2015, WB Saunders, pp 74–89. 11. Upadhyay M, Yadav S, Nagaraj K, Nanda R: Dentoskeletal and soft tissue effects of mini-implants in Class II, division 1 patients, Angle Orthod 79:240–247, 2009.

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12. Upadhyay M, Yadav S, Nagaraj K, Uribe F, Nanda R: Miniimplants vs fixed functional appliances for the treatment of young adult Class II female patients: a prospective clinical trial, Angle Orthod 82:294–303, 2012. 13. Smith RJ, Burstone CJ: Mechanics of tooth movement, Am J Orthod 85:294–307, 1984. 14. Upadhyay M, Yadav S, Nanda R: Biomechanical basis of extraction space closure. In Nanda R, editor: Esthetics and biomechanics in orthodontics, ed 2, Philadelphia, PA, 2015, WB Saunders, pp 108–120. 15. Tanne K, Koenig HA, Burstone CJ: Moment to force ratios and the center of rotation, Am J Orthod Dentofac Orthop 94:426–431, 1988. 16. Kojima Y, Kawamura J, Fukui H: Finite element analysis of the effect of force directions on tooth movement in extraction space closure with miniscrew sliding mechanics, Am J Orthod Dentofacial Orthop 142:501–508, 2012. 17. Sia SS, Shibazaki T, Yoshiyuki K, Yoshida N: Experimental determination of optimal force system required for control of anterior tooth movement in sliding mechanics, Am J Orthod Dentofacial Orthop 135:36–41, 2009. 18. Tominaga J, Tanaka M, Koga Y, Gonzales C, Masaru K, Yoshida N: Optimal loading conditions for controlled movement of anterior teeth in sliding mechanics, Angle Orthod 79:1102–1107, 2009. 19. Kojima Y, Fukui Hisao: A finite element simulation of initial tooth movement, orthodontic movement, and the center of resistance of the maxillary teeth connected with an archwire, Eur J Orthod Advance Access.1–7, 2011. 20. Kojima Y, Fukui H: Numerical simulations of en masse space closure with sliding mechanics, Am J Orthod Dentofacial Orthop 138:702.e1–6, 2010. 21. Barlow M, Kula K: Factors influencing efficiency of sliding mechanics to close extraction space: a systematic review, Orthod Craniofac Res 11:65–73, 2008.

22. Moore JC, Waters NE: Factors affecting tooth movement in sliding mechanics, Eur J Orthod 15:235–241, 1993. 23. Josell SD, Leiss JB, Rekow ED: Force degradation in elastomeric chains, Semin Orthod 3:189–197, 1997. 24. Park HS, Lee SK, Kwon OW: Group distal movement of teeth using microscrew implant anchorage, Angle Orthod 75:602–609, 2005. 25. Hee Oh Y, Park HS, Kwon TG: Treatment effects of microimplant-aided sliding mechanics on distal retraction of posterior teeth, Am J Orthod Dentofacial Orthop 139:470–481, 2011. 26. Tominaga J, Chiang PC, Ozaki H, Tanaka M, Koga Y, Bourauel C, Yoshida N: Effect of play between bracket and archwire on anterior tooth movement in sliding mechanics: a threedimensional finite element study, J Dent Biomech 3, 2012. 1758736012461269. 27. Schwaninger B: Evaluation of the straight archwire concept, Am J Orthod 74:188–196, 1978. 28. Dellinger EL: A scientific assessment of the straight-wire appliance, Am J Orthod 73:290–299, 1978. 29. Joch A, Pichelmayer M, Weiland F: Bracket slot and archwire dimensions: manufacturing precision and third order clearance, J Orthod 37:241–249, 2010. 30. Adams DM, Powers JM, Asgar K: Effects of brackets and ties on stiffness of an archwire, Am J Orthod Dentofac Orthop 91:131– 136, 1987. 31. Ouchi K, Watanabe K, Koga M, Isshiki Y, Kawada E, Oda Y: The effect of retraction forces applied to the anterior segment of orthodontic archwires: differences in wire deflection with wire size, Bull Tokyo Dent Coll 39:183–188, 1998. 32. Brantley WA, Eliades T, Litsky AS: Mechanics and mechanical testing of orthodontic materials. In Nanda R, editor: Orthodontic materials: scientific and clinical aspects, ed 2, Stuttgart, Germany, 2001, Georg Thieme Verlag, pp 28–47.

PART II

Diagnosis and Treatment Planning 2. Three-Dimensional Evaluation of Bone Sites for Mini-Implant Placement Aditya Tadinada and Sumit Yadav 3. Success Rates and Risk Factors Associated With Skeletal Anchorage Sumit Yadav and Ravindra Nanda

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2

Three-Dimensional Evaluation of Bone Sites for Mini-Implant Placement ADITYA TADINADA, SUMIT YADAV

Recent years have seen a significant increase in the use of mini-implants or temporary anchorage devices (TADs) in orthodontics. This is a valuable alternative method for improving orthodontic mechanics.1–3 With TADs being considered an absolute source of skeletal anchorage4,5 for orthodontics, stability of the TAD plays a key role in the success of this entire treatment orchestra. Osseointegration of the TAD or mini-implant was considered key to providing the desired anchorage to move teeth, but a significant change and variation in implant screw design has changed this paradigm to a large extent. Mechanical locking of the TAD into the bone is considered adequate to provide the desired primary stability required for orthodontic tooth movement. While osseointegration may help in en masse retraction or moving larger tooth segments, lack of complete osseointegration actually helps in easy removal of the TAD, after the desired results have been accomplished. A pivotal step that determines the success of orthodontic tooth movement using TADs is surgical placement of the TAD, without causing any perforation or trauma to important structures in the area. Atraumatic placement involves the consideration of several important factors like soft tissue status at the site, anatomy of the bone, tooth, the interradicular distance at the TAD site and proximity to critical anatomic structures.6 Several sites have been proposed for TAD placement, and they include the palate, anterior nasal spine, maxillary tuberosity, anterior ramus, and the mandibular retromolar areas.7 One of the most commonly used locations is the interradicular area between two teeth (see Fig. 3.1). Because the placement of these TADs requires drilling the cortical bone plate and the trabecular compartment to achieve primary stability and integration, having adequate space between the roots is critical (Fig. 2.1). Since root damage (Fig. 2.2) is a likely possibility because of the lack of adequate space, a few studies have proposed some “safe zones” for TAD placement.8 However, a safe zone can vary for different individuals and a generalized area cannot be deemed safe for all patients. If there was adequate

information regarding the critical pointers to be considered for TAD placement, the location could be changed to a true safe zone that is specific to the patient, thus avoiding any untoward perforation of critical anatomic structures in the area (see Fig. 2.2). Several critical anatomic structures, like the inferior alveolar nerve canal in the mandible and the floor of the maxillary sinus in the maxilla, must be taken into consideration during TAD placement. The size and type of the TAD and thickness of the buccal, lingual, or palatal bone plate play a crucial role in the success of TAD placement. Along with the cortical bone, trabecular bone pattern also plays a key role in integration and must be taken into consideration while treatment planning the TAD. A majority of TADs, until recently, were placed blind without any preoperative radiographic evaluation and was one of the causes for the failure of the TAD. Occasionally, a periapical radiograph or a panoramic radiograph was used to evaluate the potential TAD site, but these radiographs, although helpful, did not adequately contribute to evaluation of the TAD site. The solution was three-dimensional (3-D) evaluation of the TAD site, but the only 3-D radiographic modality available for many decades was the multislice medical computerized tomography scan (CT). Multislice CT could depict the area of interest in three dimensions, but the associated radiation was very high to be routinely used for tasks like TAD placement. The risk-benefit ratio and the governing principles of radiation safety-ALARA (as low as reasonably achievable) did not support its use for this task. The evolution of cone beam CT (CBCT) as a low-dose, high-resolution 3-D imaging alternative proved to be a major advantage for imaging the osseous structures of the maxillofacial region. A significant improvement in CBCT technology is the development of small field of view to collimate the scan to specifically capture smaller areas of interest like the TAD site. Important considerations for 3-D evaluation of the TAD/mini-implant site would be to evaluate the continuity 23

24 PA RT I I     Diagnosis and Treatment Planning

Key Pointers for Preoperative Treatment Planning of TADs Using Three-Dimensional Imaging

60 (mm) 4.04 mm 3.60 mm R

Mean : 401 Max :1655 Min : -177 SD : 288 Area : 4 mm2

L

Mean : 228 Max :1631 Min : -863 SD : 588 Area : 5 mm2

0 0

120 (mm)

• Fig. 2.1  Planning of a TAD site in the posterior mandible on an axial cone beam computerized tomography image.

60 (mm)

P

0 0

A

120 (mm)

• Fig. 2.2  Cross-sectional image showing perforation of the mesial root of tooth #14 during TAD placement.

and quality of the buccal and lingual/palatal cortical bone plates, trabecular bone pattern, interradicular distance, and the proximity to critical anatomic structures in the area. Axial sections serve as best views to evaluate the buccal and lingual bone plates and to measure interradicular distance (see Fig. 2.1). Generating cross-sectional views of the TAD site will help in measuring the available buccolingual width and mesiodistal dimensions. Presence of pathology, if any, at the site must also be evaluated. Several times, the preoperative evaluation provides information to the clinician that may lead to change of the implant site to prevent damage to critical structures in the vicinity of the site. Regardless of the TAD site and type of TAD being used, the fundamental principles for radiographic planning of TADs remain the same. TAD should be in sound bone and must have adequate stability to withstand the forces being applied. TAD placement must not lead to perforation or damage of any critical anatomic structures in its vicinity.

1. Quality and integrity of the buccal and lingual/palatal cortical bone plates. 2. Quality of the trabecular bone. 3. Proximity to critical anatomic structures like the inferior alveolar nerve canal in the mandible and the floor of the maxillary sinus in the mandible. 4. Density of the bone at the TAD site. 5. Interradicular distance at the TAD site. While CBCT depicts the area of interest in three dimensions, the challenge of radiation dose optimization and effective field size have continued to remain as limiting factors. Radiation dose from a standard CBCT exposure is approximately 20 to 40 micro Sieverts for a small volume CBCT and 80 to 200 micro Sieverts for a midsized to a large field of view scan depending on the CBCT machine.9 Dose and use are particularly critical because of the age group of most orthodontic patients. There are several techniques to optimize dose by manipulating the exposure factors like kVp and mA and time. A more recent technique is to acquire the CBCT scan with a modified rotational acquisition that rotates 180 degrees as opposed to the conventional 360 degrees rotational acquisition. This modified technique acquires images with a majority of the radiation exposure being delivered to the posterior aspect of the skull, thus avoiding direct exposure to more radiosensitive organs like the eyes, thyroid, salivary glands, and intraoral membranes.10 According to a study by Morant et al., this modified arc-based acquisition technique reduces the radiation delivered by approximately 40%, making this a much more acceptable radiographic examination for evaluating TAD sites even in younger patients.11 Significant mitigation of risk and avoiding root perforation can be achieved by preoperative treatment planning using CBCT. A major challenge is in translating the surgical plan and simulation from a virtual environment to the physical environment while placing the TAD. This in part can be overcome by fabricating a simple radiographic guide that can be modified to be a surgical guide, much like the method that is standard in planning and placement of dental implants. The radiographic guide helps in bridging the virtual environment with the physical environment. Key steps in this process include making an impression of the teeth and surrounding structures at the proposed TAD site, and then making a stone cast model of the impression and using a plastic sheet in a vacuum forming system to create a radiographic guide using a suck-down technique. A small radiographic marker can be fused to the guide at the proposed TAD site. Several commercially available radiographic markers can be used to mark the TAD site, but a small dot of heated gutta-percha serves well as an easy and

CHAPTER 2  Three-Dimensional Evaluation of Bone Sites for Mini-Implant Placement

60 (mm)

5.77 mm 4.39 mm

60 (mm)

4.47 mm

3.36 mm

Mean : 934 Max :1915 Min : –86 SD : 409 Area : 4 mm2

P

25

3.43 mm A

R

1.70 mm

Mean : –651 Max : 298 3.63 Min :–1017 SD : 209 Area : 2 mm2

1.93 mm mm L

Mean : –4 Max : 1208 Min : –835 SD : 409 Area : 1 mm2

120 (mm)

0 0

120 (mm)

• Fig. 2.3  Planning of a TAD site in the palate on a sagittal cone beam

•

practical radiographic marker. With the radiographic guide in the mouth, a small-volume focused field of view CBCT scan must be acquired. The scan will now show the area of interest in three dimensions along with the radiographic marker. Now a thorough evaluation of the potential TAD site can be done using any of the several CBCT reconstruction programs. Several CBCT reconstruction programs also provide the ability to simulate a surgical TAD placement with TADs in a variety of lengths and widths. Once the preoperative evaluation is done, the right-sized TAD and the location can be chosen and, if need be, an alternate site can be scoped out if the originally planned site shows anatomic challenges or if the site just does not have adequate interradicular space. The radiographic guide can be modified to be a surgical guide by placing a small sleeve or an opening at the planned site. The guide can be inserted into the mouth during TAD placement, and using the radiographic marker as a reference point, the TAD can be placed at the site as planned on the CBCT reconstruction program.

shown to have better bone quality and quantity, this is dependent on the age, gender, race, and stage of growth maturation.12 A careful evaluation using cross-sectional images, typically sagittal views that help in determining the best location, is helpful (Fig. 2.3). Evaluation should include setting the scanned volume aligned in the Frankfort horizontal plane, choosing the area of interest on the axial section, and then finding the corresponding area on the sagittal plane, or by generating a cross-sectional image of the site. Measurements along the palatal area for the available bone and the density of the bone should be carefully done considering the size of the TAD, as the hard palate shares a common boundary with the nasal cavity. The roof of the hard palate is the floor of the nasal cavity, and any perforation will lead to an oronasal communication and associated complications. 

computerized tomography image.

Three-Dimensional Evaluation of a Potential TAD Site in the Palate The palatal area is increasingly being used as a TAD site for molar intrusion, molar protraction, segment protraction, and anterior tooth retraction. A big reason for this is the access of this area for TAD placement, less soft tissue irritation, no interference with the desired orthodontic tooth movement, and good quality and quantity of bone. Palatal TADs are commonly inserted in the anterior region of the palate, midpalatal area, and the posterior region of the palate. Key considerations for success of TADs in the palatal area are bone quantity or the total amount of available bone for TAD insertion and bone quality as measured by density. Although the areas corresponding to the canine and second premolar in the center of the palate have been

Fig. 2.4  Planning of a TAD site in the posterior maxilla on an axial cone beam computerized tomography image.

Three-Dimensional Evaluation of a Potential TAD Site in the Maxillary Posterior Area Maxillary posterior sites are also commonly used for TAD placement, and depending on the site and choice of TAD, key principles remain the same as with most other TAD sites, but since the maxillary bone is typically thinner and less dense then the mandible, a careful evaluation of the bone density is recommended. If the TAD site is interradicular, measuring the interradicular distance at the crest and at the midroot level on cross-sectional images is valuable in the success of the procedure (Fig. 2.4). Use a radiographic guide that can be modified, as explained earlier in the chapter. 

Three-Dimensional Evaluation of a Potential TAD Site in the Buccal Shelf Area The buccal shelf area in the mandible can be used for placing a TAD. In this location, the TAD is placed

26 PA RT I I     Diagnosis and Treatment Planning

A

B

H

B

R

F A

C • Fig. 2.5  Planning of a TAD site in the buccal shelf area on a cross-sectional (A) and a volumetric (B and C) CBCT images.

parallel to the long-axis of the tooth typically distal to the distal root of the mandibular second molars. Key pointers for this location are choosing the right length of the TAD and ensuring that there is adequate circumferential bone support to prevent tipping or shearing of the TAD leading to failure. CBCT can help in locating the ideal location, and to ensure that the TAD is placed in the buccal shelf and no damage to the adjacent structures is caused (Fig. 2.5).

References 1. Papadopoulos MA, Tarawneh F: The use of miniscrew implants for temporary skeletal anchorage in orthodontics: a comprehensive review, Oral Surg Oral Med Oral Pathol Oral Radiol Endod 103:e6–e15, 2007. 2. Nienkemper M, Pauls A, Ludwig B, Wilmes B, Drescher D: Multifunctional use of palatal mini-implants, J Clin Orthod 46:679– 686, 2012.

3. Chandhoke TK, Nanda R, Uribe FA: Clinical applications of predictable force systems, part 2: miniscrew anchorage, J Clin Orthod 49:229–239, 2015. 4. Upadhyay M, Yadav S, Patil S: Mini-implant anchorage for enmasse retraction of maxillary anterior teeth: a clinical cephalometric study, Am J Orthod Dentofacial Orthop 134:803–810, 2008. 5. Upadhyay M, Yadav S, Nagaraj K, Patil S: Treatment effects of mini-implants for en-masse retraction of anterior teeth in bialveolar dental protrusion patients: a randomized controlled trial, Am J Orthod Dentofacial Orthop 134:18-29, 2008. e1. 6. Landin M, Jadhav A, Yadav S, Tadinada A: A comparative study between currently used methods and small volume-cone beam tomography for surgical placement of mini implants, Angle Orthod 85:446–453, 2014. 7. Creekmore TD, Eklund MK: The possibility of skeletal anchorage, J Clin Orthod 17:266–269, 1983. 8. Poggio PM, Incorvati C, Velo S, Carano A: “Safe zones”: a guide for miniscrew positioning in the maxillary and mandibular arch, Angle Orthod 76:191–197, 2006.

CHAPTER 2  Three-Dimensional Evaluation of Bone Sites for Mini-Implant Placement

9. Tadinada Aditya, Schneider Sydney, Yadav Sumit: Role of cone beam computed tomography in contemporary orthodontics, Semin Orthod 24(4):407–415, 2018. 10. Tadinada Aditya, Marczak Alana, Yadav Sumit: Diagnostic efficacy of a modified low-dose acquisition protocol for the preoperative evaluation of mini-implant sites, Imaging Sci Dent 47(3):141–147, 2017.

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11. Salvadó M, López M, Morant JJ, Calzado A: Monte carlo calculation of radiation dose in CT examinations using phantom and patient tomographic models, Radiat Protect Dosimetry 114(13):364–368, 2005. 12. Yadav Sumit, Sachs Emily, et al.: Gender and growth variation in palatal bone thickness and density for mini-implant placement, Prog Orthod 19(1):43, 2018.

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3

Success Rates and Risk Factors Associated With Skeletal Anchorage SUMIT YADAV, RAVINDRA NANDA

Introduction Anchorage control plays a pivotal role in the effective management of orthodontic cases for attaining both structural and facial esthetics.1–3 Assuming ideal treatment goals, anchorage requirements should be evaluated in all three planes of spaces: anterior-posterior, transverse, and vertical. Attaining maximum or absolute anchorage has always been an arduous goal for orthodontist clinicians, often resulting in a condition, dreaded by most, called anchor loss.4 In recent years, titanium mini-implants have gained enormous popularity in the orthodontic community and are being considered as absolute source of skeletal orthodontic anchorage.3,4 However, the clinical application of a mini-implant does not guarantee treatment success, and its stability is essential before it can be used for different treatment modalities. Mini-implant success rates have been the subject of uncontrolled trials, case-control study, prospective clinical study, randomized clinical trials, and systematic reviews in the past decade.3,4 Long-term studies report the success rates of more than 90% for the dental implants, whereas the success rates of orthodontic mini-implants have been reported at the rate of 35% to 95% in the literature.5 The success rates of mini-implants described in the literature show great variation, as the survival of mini-implant in the surrounding bone depends on varied factors.6,7 The success of the miniimplants usually depends on the extent to which it integrates (both mechanical and biologic) with the surrounding hard (bone) and soft tissue (gingiva and palatal mucosa).7–9 

Site of Placement and Success Rates Different anatomic sites have been used for the placement of the mini-implant. Kanomi and Costa and colleagues implanted mini-implants (1.2 mm in diameter) and miniimplants (2.0 mm in diameter) into the basal alveolar bone below the roots of the teeth to prevent the damage to the adjacent roots.10,11 However, because of ease of placement and application of orthodontic force, maxillary and mandibular buccal alveolar sites are still the preferred locations

for the placement of mini-implants. Park et  al. implanted mini-implants (1.2 mm in diameter) into the alveolar bone between the roots of the posterior teeth to increase the horizontal component of the applied force.12 In the last 5 years, palatal mini-implants have gained popularity, as the quality of underlying bone is excellent and there are no interfering morphologic structures that prevent the placement of the mini-implants.13 Recently, Chang et al. popularized the placement of Mandibular Buccal Shelf Screw (MBS) for the correction of skeletal malocclusion without orthognathic surgery, correction of severe crowing and dental proclination without the extraction of the teeth.14

Buccal Alveolar Mini-Implants/Interradicular Mini-Implants The buccal alveolar mini-implants are the most commonly placed mini-implants within the alveolar bone. The success rates of buccal alveolar/interradicular (IR) mini-implants is varied in the literature, ranging from 57% to 95%, with a mean of approximately 85%.15–17 The overall success rate of the posterior mini-implants (distal to first premolar) in the mandible and maxilla is about 83%, and with regards to individual jaw (maxilla and mandible) and success rate, the evidence is conflicting.9 Park et al.18 reported that the miniimplants in the maxilla had a higher success rate, whereas Miyawaki et al.19 and Moon et al.9 stated that the placement site of the mini-implant in the maxilla and the mandible was not related to the success rates. The success rate of miniimplants depends on numerous factors; however, for buccal alveolar/IR mini-implant, apart from other factors, the success depends on the space between the roots of the adjacent teeth where the mini-implant is supposed to be inserted. It has been shown that, for the mini-implant diameter of 1.5 mm in the maxilla, the IR distance between the adjacent teeth should be ≥3.1 mm to avoid root contact and still leave sufficient alveolar bone for the stability.20 Poggio et al. stated that safe zones for the placement of miniimplants in the maxillary arch based on the IR spaces is 5 to 11 mm above the alveolar crest in the area between the 29

30 PA RT I I    Diagnosis and Treatment Planning

second and first premolar and first premolar and canine and 5 to 8 mm above the alveolar crest for the area between first molar and second premolar. They also stated that in maxilla, the more anterior and the more apical, the safer the location becomes.20 To avoid any possible complications of implant– root contact, various mini-implant placement guides, using two-dimensional or three-dimensional imaging techniques have been proposed in orthodontic literature.21–24 Besides the diameter, angulation of mini-implant can be another important factor that should be considered. Kuroda et  al. proposed the angulation of 20 to 40 degrees to the long axis of teeth would reduce the risk of perforating the roots of the adjacent tooth.25 Another important factor for the success of mini-implants is the quality or type of soft tissue (mucosa) at placement sites. Cheng et  al. reported that the absence of keratinized mucosa around mini-implants significantly increased the risk of infection and failure (71% failure rate).26 Miniimplants in the posterior mandible are more susceptible to failure than the mini-implants in the posterior maxilla because of increased chances of infection, as there is significantly less attached gingiva available in posterior region of the mandible. Furthermore, alveolar bone in the posterior mandible is dense and overheating is more likely to occur during mini-implant placement.26 

Palatal Mini-Implants In the last decade palatal mini-implants have gained popularity as palate seems to be an ideal mini-implant placement site because of its good bone stock (bone quantity and bone quality).27 The palatal mini-implants are usually preferred because they do not interfere with the desired orthodontic tooth movement, the placement site is easily accessible, and no major blood vessels and nerves are present to interfere with the palatal mini-implant placement.27 The palatal implants are usually placed either median (in the suture area) or para-median. Investigators have studied the success of median palatal mini-implants in detail and have shown approximately 90% success rate. Karagkiolidou et al.7 showed that approximately 98% of mini-implants are stable when they are inserted in the anterior region of the palate, whereas Ono et  al. have showed 85% success rate when the mini-implants are placed in mid-palatal suture area.6

showed a higher success rate of MBS mini-implants (overall failure rate 7.2%) when compared to IR mandibular mini-implants.14 In another study, Chang et al. reported a failure rate of 5% for ramus mini-implants and stated these mini-implants as expedient, efficient, and predictable for molar uprighting.28 Although infrazygomatic region can be counted as a possible alternative to maxillary buccal IR mini-implants in maxilla, their close proximity to maxillary sinus and soft tissue overgrowth makes the infrazygomatic ridge a less suitable site for mini-implant placement. Uribe at al. reported a 21.8% failure rate of infrazygomatic mini-implants, which is way higher than a 12% failure rate of maxillary IR region.29a Furthermore, Jia et  al. reported that 78.3% infrazygomatic mini-implant perforated the maxillary sinus and should be used with caution when alternative sites are not feasible for mini-implant placement.29b 

Risk Factors The risk factors associated with the success/failure of miniimplants can be categorized into host factors and miniimplant factors (Table 3.1). The host factors, such as age, gender, bone quality and quantity, and root proximity, have been extensively studied.15,19,27,30–32 With regards to age and mini-implant stability, the evidence is inconclusive. Park et  al.33 reported that subjects younger than 15 years had more mini-implant failure than the subjects older than 15 years because of poor bone quantity and quality, whereas Park concluded that subjects younger than 20 years had significantly less mini-implant failure than the subjects ages 20 years and older.34 However, Miyawaki et al. and Moon et al. stated that there is no significant difference in mini-implant failure when compared among adolescent subjects, young adults subjects, and adult subjects.9,19 Most of the studies have reported no significant gender difference in the success rates of the mini-implants.6,18,19 Similarly, Papageorgiou et  al.5 metaanalysis lacked evidence for a positive association between mini-implant failure and patient sex or age. The quality and quantity of the alveolar bone are considered important influential factors affecting the success rate of orthodontic mini-implants.35 The cortical bone thickness is considered a decisive factor in the overall success/failure of the mini-implant. It has been shown that an increase in the cortical bone thickness in the alveolar bone of maxilla and

Extraalveolar Mini-Implants Extraalveolar (EA) mini-implants have gained popularity, and various placement sites have been evaluated to overcome side-effects of IR mini-implants. The common EA sites for mini-implant placement are: (1) infrazygomatic ridge, (2) retromolar pad area, (3) anterior border of the ramus, and (4) MBS. A need for repositioning the miniimplants during ongoing orthodontic treatment is eliminated with EA locations as they are placed away from the path of desired orthodontic tooth movement. Chang et al.

TABLE   Risk Factors for the Stability of Mini-Implants 3.1 

Host Factors

Mini-Implant Factors

• Bone quantity and quality

• Length

• Age

• Diameter

• Gender

• Material • Surface

CHAPTER 3  Success Rates and Risk Factors Associated With Skeletal Anchorage

mandible significantly increases the primary stability of the mini-implant.36,37 A recent metaanalysis showed positive association between mini-implant stability and amount of cortical bone.35 The most important mini-implant factors that affect the success rates are the diameter and length of the miniimplant, and both these factors have been thoroughly researched and studied.19,38 The published evidence has shown contradictory results with respect to the effect of the parameters of diameter and length on the miniimplant stability because of the variability of methods and samples used in the studies conducted.5,19,38 Miyawaki et al. reported that diameter and length of the miniimplant affect the stability. Increase in diameter and length of mini-implant increases the success rate of the miniimplant.19 Tseng et  al. found that mini-implant length is an important variable affecting the success/failure rates. Their research showed that the length of the miniimplant was related to success rate: 80% for 8 mm, 90% for 10 mm, and 100% for 12 mm and 14 mm.39 Similarly, Sarul et  al.38 in their prospective clinical study showed that the 8-mm mini-implants are significantly more stable than 6-mm mini-implants. In contrast to aforementioned studies, Antoszewska et al.40 in their retrospective study showed no significant relationship between the miniimplant length and increased stability. Similarly, Wilmes et  al.15 showed that the length of the mini-implants does not have significant effects on their success when measuring the primary stability. Similarly, Papageorgiou et al.5 in their metaanalysis revealed no significant association with mini-implant stability and mini-implant length. The mini-implant diameter also affects the primarily stability (i.e., success rate). Miyawaki et al. reported that success rate of mini-implants with 1.5 mm or 2.3 mm diameter was significantly greater than mini-implant with a diameter of 1 mm. Similarly, Berens et al.41 reported that 2-mm miniimplant (vs. 1.2 mm) had a higher success rate in the mandible and 1.5-mm mini-implant had a higher success rate in the palate. 

Conclusion In conclusion, selection of the location of mini-implants should be based on quality and quantity of cortical bone, knowledge of adjacent anatomic structures like roots of teeth, maxillary sinus, inferior alveolar canal, and proposed biomechanics to maximum success. Three-dimensional imaging technique should be used as and when required to avoid the possible penetration of sensitive anatomic structures.42 Lastly, proper oral hygiene practice should be encouraged to minimize the potential risk of peri-implantitis.

References 1. Yadav S, Upadhyay M, Roberts WE: Biomechanical and histomorphometric properties of four different mini-implant surfaces, Eur J Orthod. 37(6):627–635, 2015.

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2. Yadav S, et al.: Microdamage of the cortical bone during miniimplant insertion with self-drilling and self-tapping techniques: a randomized controlled trial, Am J Orthod Dentofacial Orthop 141(5):538–546, 2012. 3. Upadhyay M, et al.: Treatment effects of mini-implants for enmasse retraction of anterior teeth in bialveolar dental protrusion patients: a randomized controlled trial, Am J Orthod Dentofacial Orthop 134(1):18–29 e1, 2008. 4. Upadhyay M, Yadav S, Patil S: Mini-implant anchorage for enmasse retraction of maxillary anterior teeth: a clinical cephalometric study, Am J Orthod Dentofacial Orthop 134(6):803–810, 2008. 5. Papageorgiou SN, Zogakis IP, Papadopoulos MA: Failure rates and associated risk factors of orthodontic miniscrew implants: a meta-analysis, Am J Orthod Dentofacial Orthop 142(5):577–595 e7, 2012. 6. Uesugi S, et  al.: Stability of secondarily inserted orthodontic miniscrews after failure of the primary insertion for maxillary anchorage: maxillary buccal area vs midpalatal suture area, Am J Orthod Dentofacial Orthop 153(1):54–60, 2018. 7. Karagkiolidou A, et  al.: Survival of palatal miniscrews used for orthodontic appliance anchorage: a retrospective cohort study, Am J Orthod Dentofacial Orthop. 143(6):767–772, 2013. 8. Manni A, et al.: Factors influencing the stability of miniscrews. A retrospective study on 300 miniscrews, Eur J Orthod 33(4):388– 395, 2011. 9. Moon CH, et al.: Factors associated with the success rate of orthodontic miniscrews placed in the upper and lower posterior buccal region, Angle Orthod. 78(1):101–106, 2008. 10. Kanomi R: Mini-implant for orthodontic anchorage, J Clin Orthod 31(11):763–767, 1997. 11. Costa A, Raffainl M, Melsen B: Miniscrews as orthodontic anchorage: a preliminary report, Int J Adult Orthodon Orthognath Surg 13(3):201–209, 1998. 12. Park HS, et al.: Micro-implant anchorage for treatment of skeletal Class I bialveolar protrusion, J Clin Orthod 35(7):417–422, 2001. 13. Kim HJ, et  al.: Soft-tissue and cortical-bone thickness at orthodontic implant sites, Am J Orthod Dentofacial Orthop 130(2):177–182, 2006. 14. Chang C, Liu SS, Roberts WE: Primary failure rate for 1680 extra-alveolar mandibular buccal shelf mini-screws placed in movable mucosa or attached gingiva, Angle Orthod 85(6):905– 910, 2015. 15. Wilmes B, et al.: Parameters affecting primary stability of orthodontic mini-implants, J Orofac Orthop 67(3):162–174, 2006. 16. Huja SS, et al.: Pull-out strength of monocortical screws placed in the maxillae and mandibles of dogs, Am J Orthod Dentofacial Orthop 127(3):307–313, 2005. 17. Ure DS, et al.: Stability changes of miniscrew implants over time, Angle Orthod 81(6):994–1000, 2011. 18. Park HS, Jeong SH, Kwon OW: Factors affecting the clinical success of screw implants used as orthodontic anchorage, Am J Orthod Dentofacial Orthop 130(1):18–25, 2006. 19. Miyawaki S, et al.: Factors associated with the stability of titanium screws placed in the posterior region for orthodontic anchorage, Am J Orthod Dentofacial Orthop 124(4):373–378, 2003. 20. Poggio PM, et al.: “Safe zones”: a guide for miniscrew positioning in the maxillary and mandibular arch, Angle Orthod 76(2):191– 197, 2006. 21. Dasari AK, et al.: A simple 2D accurate mini implant positioning guide, JCDR(7)8, ZM03-ZM4. 2014.

32 PA RT I I    Diagnosis and Treatment Planning

22. Gandhi VMF: Simple and chairside construction and placement of guide for accurate positioning of orthodontic miniimplants, J Orthod Endod.(2)1, 2015. 23. Sharma K, Sangwan A: KS. Micro-implant placement guide, Ann Med Health Sci Res. 4(Suppl 3):S326–S328, 2014. 24. Ludwig B, et al.: Anatomical guidelines for miniscrew insertion: vestibular interradicular sites, J Clin Orthod 45(3):165–173, 2011. 25. Kyung HM, et al.: Development of orthodontic micro-implants for intraoral anchorage, J Clin Orthod 37(6):321–328, 2003; quiz 314. 26. Cheng SJ, et al.: A prospective study of the risk factors associated with failure of mini-implants used for orthodontic anchorage, Int J Oral Maxillofac Implants 19(1):100–106, 2004. 27. Yadav S, et  al.: Gender and growth variation in palatal bone thickness and density for mini-implant placement, Prog Orthod 19(1):43, 2018. 28. Chang CH, Lin JS, Eugene Roberts W: Ramus screws: the ultimate solution for lower impacted molars, Semin Orthod. 24(1):135–154, 2018. 29a. Uribe F, et al.: Failure rates of mini-implants placed in the infrazygomatic region, Prog Orthod 16:31, 2015. 29b. Jia X, Chen X, Huang X. Influence of orthodontic mini-implant penetration of the maxillary sinus in the infrazygomatic crest region. Am J Orthod Dentofacial Orthop. 153(5):656–661, 2018. https://doi.org/10.1016/j.ajodo.2017.08.021. 30. Deguchi T, et  al.: Quantitative evaluation of cortical bone thickness with computed tomographic scanning for orthodontic implants, Am J Orthod Dentofacial Orthop 129(6):721 e7–12, 2006. 31. Farnsworth D, et al.: Cortical bone thickness at common miniscrew implant placement sites, Am J Orthod Dentofacial Orthop 139(4):495–503, 2011. 32. Park J, Cho HJ: Three-dimensional evaluation of interradicular spaces and cortical bone thickness for the placement and initial

stability of microimplants in adults, Am J Orthod Dentofacial Orthop 136(3):314 e1–12, 2009; discussion 314–315. 33. Park YC, Lee KJ, Lee JS. Atlas of contemporary orthodontics. Shin Hung International, ed. Seoul: S.H. International; 2005. 34. Park HS: Clinical study on success rate of microscrew implants for orthodontic anchorage, Korea J Orthod 2003(33):151–156, 2003. 35. Marquezan M, et al.: Does cortical thickness influence the primary stability of miniscrews? A systematic review and meta-­ analysis, Angle Orthod 84(6):1093–1103, 2014. 36. Motoyoshi M, et  al.: Factors affecting the long-term stability of orthodontic mini-implants, Am J Orthod Dentofacial Orthop 137(5):588 e1–5, 2010; discussion 588–589. 37. Motoyoshi M, et al.: Effect of cortical bone thickness and implant placement torque on stability of orthodontic mini-implants, Int J Oral Maxillofac Implants 22(5):779–784, 2007. 38. Sarul M, et  al.: Effect of the length of orthodontic mini-screw implants on their long-term stability: a prospective study, Angle Orthod 85(1):33–38, 2015. 39. Tseng YC, et al.: The application of mini-implants for orthodontic anchorage, Int J Oral Maxillofac Surg 35(8):704–707, 2006. 40. Antoszewska J, et  al.: Five-year experience with orthodontic miniscrew implants: a retrospective investigation of factors influencing success rates, Am J Orthod Dentofacial Orthop 136(2):158 e1–10, 2009; discussion 158–159. 41. Berens A, Wiechmann D, Dempf R: Mini- and micro-screws for temporary skeletal anchorage in orthodontic therapy, J Orofac Orthop 67(6):450–458, 2006. 42. Tadinada A, Schneider S, Yadav S: Role of cone beam computed tomography in contemporary orthodontics, Semin Orthod. 24(4):407–415, 2008.

PART III

Palatal Implants

4. Space Closure for Missing Upper Lateral Incisors Bjöern Ludwig and Bettina Glasl 5. Predictable Management of Molar Three-Dimensional Control with i-station Yasuhiro Itsuki 6. MAPA: The Three-Dimensional Mini-Implants-Assisted Palatal Appliances and One-Visit Protocol B. Giuliano Maino, Luca Lombardo, Giovanna Maino, Emanuele Paoletto and Giuseppe Siciliani 7. Asymmetric Noncompliance Upper Molar Distalization in Aligner Treatment Using Palatal TADs and the Beneslider Benedict Wilmes and Sivabalan Vasudavan

33 33

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4

Space Closure for Missing Upper Lateral Incisors BJÖERN LUDWIG, BETTINA GLASL

Aplasia of permanent teeth is not uncommon1—it has a prevalence of 1.5% to 11.3%.2–4 Aside from wisdom teeth, lower second premolars are the most commonly affected, followed by upper lateral incisors.2 The prevalence of this is between 1% and 2%,5 but there is evidence of a slightly increased prevalence for women.6 Although the mechanism of occurrence has not yet been fully explained, genetic causes are considered important (co)factors in this regard.7,8 Previous studies have expressed suspicion that genetic factors may influence aplasia of permanent teeth. This matter has been investigated, for example, in comparative studies on identical twins.9

Therapy Options to Replace Upper Lateral Incisors There are different treatment options in the event of aplasia of upper lateral incisors. In terms of differential types of diagnosis, this can include leaving the deciduous tooth, as long as possible,10 tooth transplant,11 singletooth implant,12 or prosthetic restoration with an adhesive bridge.13,14,15 This article points out the diagnostic and therapeutic aspects of orthodontic space closure.16 It should be noted that regardless of the chosen therapy (space closure or space opening), it is necessary to weigh the patient-specific aspects to satisfy the individual, aesthetic, and functional requirements in the best possible way. For example, the following aspects play a role in diagnosis and therapy planning12,14–18 (Fig. 4.1). • Profile type • Skeletal and dental relations and occlusion • Shape and color of the canine, as well as the root shape and length • Eruption position of the canine and symmetric or asymmetric distribution of aplasia • Oral hygiene, patient motivation, and the condition of the dentition • Smile and gingival line 

Prosthetic–Implantologic Solution A prosthetic–implantologic solution is not recommended in younger patients with incomplete growth, since an infraposition of the implant can occur in the course of further vertical development of the alveolar process, after early implantation.19–24 Not only growth, but aging can also affect the vertical eruption of teeth (Fig. 4.2). However, if the decision is made in favor of an implant, a number of different critical aspects have to be considered.25–27 Root reapproximation of central incisors and canines after orthodontic treatment has also been reported.27 The toothless alveolar process is also subject to constant changes.28 In this regard, it has been found that during the orthodontic space opening, in the area of the missing lateral incisors,29 a decrease in the vestibulooral width by up to 15% can occur. 

Orthodontic Space Closure: Anchorage and Biomechanics If the decision is made in favor of orthodontic space closure, several aspects must be considered that significantly influence the final treatment results. These can be classified into esthetic, functional, and biomechanical aspects. To move teeth, anchorage is needed. The forces acting on the teeth are reciprocal in accordance with Newton’s third law.17 Reclined anterior teeth and, especially in unilateral spaces, deviations of the middle of the arch, can have undesirable side effects. If the movement of a tooth segment is undesirable, it must be anchored in a stable manner. This can be done reliably by means of skeletal anchorage.30 As some sort of possible biomechanics, the so-called mesial slider is primarily used these days31 (Fig. 4.3). 

Palatal Screw Selection and Insertion Searching for the best insertion site in the maxilla, the anterior palate appears to be the best.67,68 It is characterized by 35

36 PA RT I I I    Palatal Implants

4

A

3

1

B • Fig. 4.1  Esthetic aspects influencing space closure or space opening. (A) Male patients with a low smile

line, without gingival display. Therapy: space opening and insertion of dental implants in regions 12 and 22. (B) Female patient with a high smile line and “gummy-smile.” Therapy: orthodontic space closure and cosmetic tooth reshaping of the mesialized teeth.

A

B • Fig. 4.2  Vertical change in the tooth-implant relation in adulthood. (A) After the implant insertion, the natural teeth erupted by about 2 mm during 8 years, in relation to the implant. (B) The implant is infrapositioned in relation to the lips.

the least loss rates,32 a reliable and easy clinical identification of the ideal insertion spot, and unlimited biomechanical diversity.33 The amount of horizontal bones at the anterior palate is huge, and thus the mini-implants (MIs) diameter is not limited. The length of the MIs should not exceed 8 to 9 mm because the vertical bone availability is limited.34 Moreover, the thinly attached gingiva is required for a complication-free usage period of the MIs.35 The anterior palate

is covered by only a thin layer of keratinized gingiva, with a thickness of about 1.5 mm.36,37 In conclusion, two MIs, 7 to 9 mm in length, about 1.8 to 2.3 mm in diameter, and with a 1.5- to 2-mm transgingival neck are recommended. Since palatal placed MIs, unlike those placed interradicular, never interfere with tooth movement, their use provides the maximum level of flexibility for biomechanical considerations, in terms of treatment planning.38,39

CHAPTER 4  Space Closure for Missing Upper Lateral Incisors

37

B

4 3

A

1

C • Fig. 4.3  Orthodontic space closure with aplasia of upper lateral incisors. (A) Initial situation—missing 12

and 22. (B) Mini-implants supported T-mesial slider. (C) Final situation after cosmetic reshaping of the upper anterior teeth and the insertion of a fixed retainer.

B

A

C D

E

• Fig. 4.4  T-Mesial slider and components. (A) A universal key (screwdriver) is used to fix all screw parts.

(B) Mobile locks with hooks for the coil spring or elastic traction. (C) The sliding tubes are inserted into the standard lingual sheaths on the first molars. (D) A superelastic closed coil spring is used between the anterior lock and the sliding tube. (E) A compressed push coil can be applied to the sliding tube from a distal lock, without a hook on the U-shaped bar.

Mesial Sliding Appliance The basic part of the T-Mesial slider is a prefabricated abutment plate attached with two laser-welded wires (Fig. 4.4).40,41 Both wires are made from stainless steel. The anterior wire has a dimension of 0.8 mm and the

posterior one of 1.1 mm. The anterior wire is adapted to touch (or be bonded to) the lingual surfaces of the central incisors, while the posterior wire is shaped to be almost parallel the posterior teeth. After adaptation of the basic framework, the different individual components

38 PA RT I I I    Palatal Implants

B 1

C 1 = 1N 2 = 2-2.5 N 3 = 2-2.5 N 2

A

3

• Fig. 4.5  Shows a diagrammatic representation of the optional force systems for the protraction.

• The force level of the nickel-titanium springs between the anterior lock and the posterior sliding tube should be about 250 grams. • Elastic chains are used between the central incisors and canines. Additional elastics and/or compressed coil springs can be used labially or lingually, ad libitum, between the molars and premolars since the anchorage is stationary. • The U-shaped bar can be activated to guide the first molars for expansion/compression and/or for intrusion/extrusion.

selected are attached, as shown in Fig. 4.4. After selection of appropriate components of the T-Mesial slider, it is attached to the palatal mini-implants and then activated. Fig. 4.5 shows a diagrammatic representation of the optional force systems for the protraction. 

Interdisciplinary Aspects of Finishing When Closing the Space

subsequent veneer or composite restoration of the first premolar, is recommended.41,46,47 This can also enable group guidance. The palatal cusp of the first premolar can cause occlusal interference in lower jaw movement, which can be countered by selective odontoplasty,48,49 as well as by a slight mesial rotation.50–52 

Gingivectomy It may be useful to perform a circumscribed modeling pertaining to gingivectomy/ostectomy of the canine, in addition to the intrusion.16,41 

The final reshaping restoration that makes the “role reversal” perfect can be done using composite or ceramic.39,42,60–62 There is evidence in the literature that in the case of aplasia of upper lateral incisors, the central incisors are generally narrower40—this may also necessitate their widening.41 But before this can be done in an ideal way, orthodontic “finishing” must be performed. The important tasks here are as follows.

The Canine Torque

The First Premolar

Extrusion

Various authors have considered the first premolars to be suitable to establish a “canine-equivalent” closure via veneers or composite abutments.41–44

In addition to mesialization, the tooth is extruded to match the higher localized gingival curve of the canine to the marginal aspect of a lateral incisor. The fact that the gingival margin follows crownward in an extrusive orthodontic movement53 is exploited here. The canine tip can be successively remodeled via odontoplastics.54 

Torque The root of the first premolar, which replaces the canine, must be provided with a buccal root torque to mimic (for aesthetic reasons) the root prominence of a canine.45 

Intrusion For esthetic and functional reasons, an intrusion (to achieve the optimal gingival course in relation to the adjacent teeth), with

The anatomic difference of the root morphology between the lateral incisor and the canine often requires a palatal root torque of the mesialized canine—this can be applied, for example, via a suitable bracket, and, if necessary, can be additionally amplified by third order (= torque) bends. 

Occlusion After Space Closure An average lateral incisor has a mesiodistal extension of about 7 mm, corresponding to the width of a premolar. The incisor is set neutral in the “canine area” (angle class 1) and distally in the molar area (angle class 2)17 (Figs. 4.6 and 4.7). 

CHAPTER 4  Space Closure for Missing Upper Lateral Incisors

1

A

B

3

39

4

C

• Fig. 4.6  Vertical tooth movement during the orthodontic space closure to establish a harmonious gingiva

line and the design of functional and esthetic canine reshaping. (A) Initial situation with failure 12 and 22. (B) Bracket repositioning after successful space closure for single tooth corrections that are still necessary. (C) Final situation before reshaping the tooth numbers 1, 3, and 4.

A

B • Fig. 4.7  Orthodontic space closure and SMILE–design. (A) Virtual SMILE design. (B) Final situation after reshaping the teeth by means of ceramic veneers.

Conclusion The T-Mesial slider, secured by two splinted palatal miniimplants, is an efficient noncompliance appliance that enables fast and secure space closure by the protraction of an entire maxillary dentition. By integrating such space closure with esthetic dentistry, an attractive display of the anterior dentition is obtainable in patients with unilateral or bilateral agenesis of maxillary lateral incisor(s) and concomitant malocclusions, even in cases that previously were deemed difficult or impossible to treat. Orthodontic space closure offers the ability to replace a missing tooth with a different tooth of the same person. When treatment starts on a young patient, it is usually completed during his/her adolescence. Close interdisciplinary coordination is very helpful in this regard.

References 1. Fekonja A: Hypodontia in orthodontically treated children, Eur J Orthod 27(5):457–460, 2005. 2. Polder BJ, et  al.: A meta-analysis of the prevalence of dental agenesis of permanent teeth, Community Dent Oral Epidemiol 32(3):217–226, 2004. 3. Larmour CJ, et al.: Hypodontia—a retrospective review of prevalence and etiology. Part I, Quintessence Int 36(4):263–270, 2005. 4. Baccetti T: A controlled study of associated dental anomalies, Angle Orthod 68(3):267–274, 1998. 5. Robertsson S, Mohlin B: The congenitally missing upper lateral incisor. A retrospective study of orthodontic space closure versus restorative treatment, Eur J Orthod 22(6):697–710, 2000.

6. Aasheim B, Ogaard B: Hypodontia in 9-year-old Norwegians related to need of orthodontic treatment, Scand J Dent Res 101(5):257–260, 1993. 7. Vastardis H: The genetics of human tooth agenesis: new discoveries for understanding dental anomalies, Am J Orthod Dentofacial Orthop 117(6):650–656, 2000. 8. Matalova E, et  al.: Tooth agenesis: from molecular genetics to molecular dentistry, J Dent Res 87(7):617–623, 2008. 9. Ulrich K: [Isolated canine aplasia in monozygotic twins], Fortschr Kieferorthop 50(5):415–422, 1989. 10. Kokich VG: Orthodontic and nonorthodontic root resorption: their impact on clinical dental practice, J Dent Educ 72(8):895– 902, 2008. 11. Plakwicz P, Wojtowicz A, Czochrowska EM: Survival and success rates of autotransplanted premolars: a prospective study of the protocol for developing teeth, Am J Orthod Dentofacial Orthop 144(2):229–237, 2013. 12. Kinzer GA, Kokich Jr VO: Managing congenitally missing lateral incisors. Part III: single-tooth implants, J Esthet Restor Dent 17(4):202–210, 2005. 13. Kern M: Fifteen-year survival of anterior all-ceramic cantilever resin-bonded fixed dental prostheses, J Dent 56:133–135, 2017. 14. Kinzer GA, Kokich Jr VO: Managing congenitally missing lateral incisors. Part II: tooth-supported restorations, J Esthet Restor Dent 17(2):76–84, 2005. 15. Kokich Jr VO, Kinzer GA: Managing congenitally missing lateral incisors. Part I: canine substitution, J Esthet Restor Dent 17(1):5– 10, 2005. 16. Schopf P: In Schopf P, editor: Curriculum Kieferorthopädie. Band I + II. 4., überarbeitete und erweiterte Auflage, Berlin, 2008, Quintessenz-Verlag.

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17. Brough E, Donaldson AN, Naini FB: Canine substitution for missing maxillary lateral incisors: the influence of canine morphology, size, and shade on perceptions of smile attractiveness, Am J Orthod Dentofacial Orthop 138(6):705.e1–705.e9, 2010. 18. Thilander B, Odman J, Lekholm U: Orthodontic aspects of the use of oral implants in adolescents: a 10-year follow-up study, Eur J Orthod 23(6):715–731, 2001. 19. Behr M, et al.: Concepts for the treatment of adolescent patients with missing permanent teeth, Oral Maxillofac Surg 12(2):49–60, 2008. 20. Kennedy DB: Orthodontic management of missing teeth, J Can Dent Assoc 65(10):548–550, 1999. 21. Fudalej P, Kokich VG, Leroux B: Determining the cessation of vertical growth of the craniofacial structures to facilitate placement of single-tooth implants, Am J Orthod Dentofacial Orthop 131(4):S59–S67, 2007. 22. Thilander B, et al.: Aspects on osseointegrated implants inserted in growing jaws. A biometric and radiographic study in the young pig, Eur J Orthod 14:99–109, 1992. 23. Odman J, et  al.: The effect of osseointegrated implants on the dento-alveolar development. A clinical and radiographic study in growing pigs, Eur J Orthod 13:279–286, 1991. 24. Carter NE, et al.: The interdisciplinary management of hypodontia: orthodontics, Br Dent J 194(7):361–366, 2003. 25. Olsen TM, Kokich VG: Postorthodontic root approximation after opening space for maxillary lateral incisor implants, Am J Orthod Dentofacial Orthop 137(2):158.e1–158.e8, 2010. 26. Dickinson G: Space for missing maxillary lateral incisorsorthodontic perceptions, Ann R Australas Coll Dent Surg 15: 127–131, 2000. 27. Spear FM, Mathezus DM, Kokich VG: Interdisciplinary management of single-tooth implants, Semin Orthod 3(1):45–72, 1997. 28. Uribe F, et  al.: Alveolar ridge width and height changes after orthodontic space opening in patients congenitally missing maxillary lateral incisors, Eur J Orthod 35(1):87–92, 2011. 29. Ludwig B, et al.: Mini-implantate in der Kieferorthopädie, Innovative Verankerungskonzepte, Berlin, 2007, Quintessenz. 30. Ludwig B, Zachrisson BU, Rosa M: Non-compliance space closure in patients with missing lateral incisors, J Clin Orthod 47(3):180–187, 2013. 31. Lim HJ, et al.: Factors associated with initial stability of miniscrews for orthodontic treatment, Am J Orthod Dentofacial Orthop 136(2):236–242, 2009. 32. Wilmes B, Drescher D: A miniscrew system with interchangeable abutments, J Clin Orthod 42(10):574–580, 2008; quiz 595. 33. Ludwig B, et al.: Anatomical guidelines for miniscrew insertion: palatal sites, J Clin Orthod 45(8):433–441, 2011. 34. Ludwig B, Baumgaertel S, Bowman JS: Mini-implants in orthodontics. Innovative anchorage Concepts, ed 1, London, 2008, Quintessence Publishing Co Ltd. 35. Kang S, et al.: Bone thickness of the palate for orthodontic miniimplant anchorage in adults, Am J Orthod Dentofacial Orthop 131(4 Suppl l):S74–S81, 2007. 36. Kim H-J, et  al.: Soft-tissue and cortical-bone thickness at orthodontic implant sites, Am J Orthod Dentofacial Orthop 130(2):177–182, 2006. 37. Ludwig B, Glasl B, Walde K: Miniscrews in the anterior palate, Orthodontic Products 9:91–94, 2011. 38. Antoszewska J, et  al.: Five-year experience with orthodontic miniscrew implants: a retrospective investigation of factors influencing success rates, Am J Orthod Dentofacial Orthop 136(2), 2009: 158 e1–10; discussion 158-9.

39. Wilmes B, Bowman JS, Baumgaertel S: Fields of Application of mini-implants. In Ludwig B, Baumgaertel S, Bowman JS, editors: Mini-implants in orthodontics. Innovative anchorage Concepts, London, 2008, Quintessence Publishing Co Ltd, pp 91–122. 40. Baumgaertel S: Maxillary molar movement with a new treatment auxiliary and palatal miniscrew anchorage, J Clin Orthod 42(10):587–589, 2008; quiz 596. 41. Zachrisson BU: Improving orthodontic results in cases with maxillary incisors missing, Am J Orthod 73(3):274–289, 1978. 42. Hourfar J, et al.: Esthetic Provisional restoration after space closure in patients with missing upper lateral incisors, J Clin Orthod 50(6):348–357, 2016. 43. Olivadoti A, Doldo T, Treccani M: Morpho-dimensional analysis of the maxillary central incisor clinical crown in cases of congenitally missing upper lateral incisors, Prog Orthod 10(1):12–19, 2009. 44. Zachrisson BU, Rosa M, Toreskog S: Congenitally missing maxillary lateral incisors: canine substitution, Point. Am J Orthod Dentofacial Orthop 139(4), 2011. 45. Convissar RA: Reshaping a first premolar with a composite resin to replace a missing canine, Gen Dent 34(4):301–302, 1986. 46. Zachrisson BU, Stenvik A: Single implants-optimal therapy for missing lateral incisors? Am J Orthod Dentofacial Orthop 126(6):13–15, 2004. 47. Manhart J: [Anterior esthetics with adhesive porcelain veneers], Schweiz Monatsschr Zahnmed 121(1):27–50, 2011. 48. Cozzani G, et  al.: Closure of central incisor spaces: a 16-year follow-up, J Clin Orthod 45(6):321–327, 2011. 49. Kokich V: Esthetics and anterior tooth position: an orthodontic perspective. Part II: vertical position, J Esthet Dent 5(4):174–178, 1993. 50. Kokich V: Esthetics and anterior tooth position: an orthodontic perspective. Part III: Mediolateral relationships, J Esthet Dent 5(5):200–207, 1993. 51. Biggerstaff RH: The orthodontic management of congenitally absent maxillary lateral incisors and second premolars: a case report, Am J Orthod Dentofacial Orthop 102(6):537–545, 1992. 52. Park JH, et  al.: Orthodontic treatment of a congenitally missing maxillary lateral incisor, J Esthet Restor Dent 22(5):297–312, 2010. 53. Miller TE: Anterior esthetics achieved with orthodontic therapy: a report of three cases, J Esthet Dent 1(5):145–154, 1989. 54. Czochrowska EM, et al.: Outcome of orthodontic space closure with a missing maxillary central incisor, Am J Orthod Dentofacial Orthop 123(6):597–603, 2003. 55. Fiorillo G, Festa F, Grassi C: Upper canine extractions in Adult cases with Unusual malocclusions, J Clin Orthod 46(2):102–110, 2012. 56. Salama H, Salama M: The role of orthodontic extrusive remodeling in the enhancement of soft and hard tissue profiles prior to implant placement: a systematic approach to the management of extraction site defects, Int J Periodontics Restorative Dent 13(4):312–333, 1993. 57. Thordarson A, Zachrisson BU, Mjor IA: Remodeling of canines to the shape of lateral incisors by grinding: a long-term clinical and radiographic evaluation, Am J Orthod Dentofacial Orthop 100(2):123–132, 1991. 58. Zachrisson BU, Rosa M, Toreskog S: Congenitally missing maxillary lateral incisors: canine substitution, Am J Orthod Dentofacial Orthop 139(4):434, 2011.

CHAPTER 4  Space Closure for Missing Upper Lateral Incisors

59. Rosa M, Zachrisson BU: The space-closure alternative for missing maxillary lateral incisors: an update, J Clin Orthod 44(9): 540–549, 2010. 60. Rosa M, Zachrisson BU: Integrating space closure and esthetic dentistry in patients with missing maxillary lateral incisors, J Clin Orthod 41(9):563–573, 2007. 61. Rosa M, Zachrisson BU: Integrating esthetic dentistry and space closure in patients with missing maxillary lateral incisors, J Clin Orthod 35(4):221–234, 2001. 62. Zimmer B, Seifi-Shirvandeh N: Routine treatment of bilateral aplasia of upper lateral incisors by orthodontic space closure without mandibular extractions, Eur J Orthod 31(3):320–326, 2009. 63. Graham JW: Temporary replacement of maxillary lateral incisors with miniscrews and bonded pontics, J Clin Orthod 41(6):321– 325, 2007. 64. Kokich VG, Swift Jr EJ: Temporary restoration of maxillary lateral incisor implant sites, J Esthet Restor Dent 23(3):136–137, 2011.

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65. Goellner P: Bilateral protraction of the entire upper arch to Substitute central incisors with lateral incisors. In Cope JB, editor: Ortho TADs the clinical guide and Atlas, Dallas, 2007, Under Dog Media LP, pp 415–418. 66. Ludwig B, et al.: Anatomical guidelines for miniscrew insertion: vestibular interradicular sites, J Clin Orthod 45(3):165–173, 2011. 67. Wehrbein H, et  al.: The Orthosystem--a new implant system for orthodontic anchorage in the palate, J Orofac Orthop 57(3): 142–153, 1996. 68. Park HS: Clinical study on success rate of microscrew implants for orthodontic anchorage, Korean J Orthod 33(3):151–156, 2003. 69. Gunduz E, et al.: Acceptance rate of palatal implants: a questionnaire study, Am J Orthod Dentofacial Orthop 126(5):623–626, 2004.

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5

Predictable Management of Molar Three-Dimensional Control with i-station YASUHIRO ITSUKI

Extraalveolar Anchorage Through the i-station Device Extraalveolar sites for placement of skeletal anchorage units enable the fabrication of different appliances that can deliver more complex force systems than those achieved with interdental mini-implants. The appliances that can be designed allow force delivery systems that assist in correcting a large number of malocclusions that would otherwise be difficult to manage with conventional mechanotherapy. We have designed a unique appliance from which a large number of interchangeable components may be added depending on the biomechanical needs. The i-station consists of two mini-implants (i-screws), on which an abutment (i-platform) is placed. A suprastructure (i-arm plate/i-arm square wire) that controls the force systems is secured to this platform through three fasteners (i-caps). The components assemble together in the following manner: i-platform connects to the i-screws and the i-arm/i-arm square wires are fixed to the i-platform.1–4 The i-station can be used both in the maxilla (Fig. 5.1A–B) and mandible (Fig 5.1C–D), with minor changes in the components of the device. The main difference is in the i-platform size, which is larger in the mandible and also adjustable by cutting the length, depending on the anatomic characteristics of each patient. The maxillary i-station consists of two i-screws that are placed along the posterior region of the midpalatal suture from which the suprastructure (i-arm plate/i-arm square wire) is fixed to an i-platform connection. On the other hand, the mandibular i-station is placed in the oblique ridge of the mandible and consists of two screws that fix the i-platform3 at each end. The i-station has the following attributes: 1) No incision is required for its insertion either in the maxilla or mandible. The i-screw has a broad base on the attachment head that acts as a stop, preventing the i-platform from burying into the mucosa and causing tissue irritation (Fig. 5.2A).

2) The i-platform allows for i-screw placement freedom. Only one of the i-screws has a precise fit within the i-platform, allowing the second i-screw to be placed within a range of positions. This ensures flexibility during insertion based on patient’s anatomy (Fig. 5.2B). 3) Tight fit (Fig. 5.2C). The i-screw head and the i-platform hole are both hexagonal. The tight interaction of both components prevents the i-platform from resulting in a loose fit. 4) Easy assembly (Fig. 5.2D). Even if the two i-screws are not parallel, or if the height of the attachment head is at different levels, the i-platform can still be installed. There are two grooves in the i-platform, which can be adjusted to conform to different i-screw angles and heights. This adjustment can be easily done with a band pusher. 5) Interchangeable i-arm plate/i-arm square wire (Fig. 5.2E). The i-arm plate/i-arm square wire can easily be replaced by removing the i-cap. Therefore it is interchangeable to conform to different force delivery systems. 6) Tooth movement along 360 degrees (Fig. 5.2F). The i-arm plate/i-arm square wire can be attached at different angles (in 45-degree increments) to the flower attachment head of the i-platform, allowing a full circumferential range of force delivery vectors. 7)  Weldable components (Fig. 5.2G). Brackets can be welded to the i-arm plate, and beta-titanium wires can be used to create complex force systems.

Light and Efficient Force Systems In theory, to perform bodily tooth movement, a force vector must be created that passes through the center of resistance of the entire dentition (Fig. 5.3A). However, the dentition is not a rigid body; each tooth has its own center of resistance, and any given archwire tends to bend when applying a force (Fig. 5.3B). Increasing the rigidity of the wire may allow bodily tooth movement, but the tooth will not move unless a very strong force is applied (Fig. 5.3C). If this applied force is very high, the possibility of anchor mini-implant failure increases. 43

44 PA RT I I I    Palatal Implants

A

B

C

D • Fig. 5.1  i-station structure.  (A) Maxillary i-station. a. i-screw; b. i-platform; c. i-cap; d. i-arm square wire; e. i-arm plate. (B) i-station placed in the posterior midpalatal suture. (C) Mandibular i-station (same as A except for b which is i-platform3). (D) Mandibular i-station placed in the oblique ridge.

Controlling the first molar in three dimensions is critical in orthodontics. The i-station provides this control as it counteracts the resulting rotational tendencies of the applied forces at the coronal level. For example, when exerting a distalizing force on a lingual tube on the first molar with an open coil from the mesial side, a rotational moment is generated and the tooth will tip distally (Fig. 5.4A). The reason for this type of molar tooth movement is because the center of resistance of the tooth and the point of force application are different. This also results in binding, which further suppresses tooth movement. This same principle ensues when evaluating the force system from an occlusal perspective, where molar rotation is observed with the applied force (Fig. 5.4B). In loop mechanics, the following wire adjustments can be done to offset the tipping and rotational tendencies described earlier. A 0.032 × 0.032-in vertical loop in a betatitanium wire is inserted from the i-arm plate to the bracket on the lingual surface of the molar (Fig. 5.4C). From a second-order perspective, to offset the tipping of the molar that will be generated with a distal force, the loop is prebent to create an uprighting moment. Hence when the wire is inserted into the lingual bracket, tipping and uprighting moments are simultaneously generated, which causes bodily movement of the tooth without distal tipping. In addition, from the occlusal perspective, the loop is twisted so a disto-palatal rotation moment is applied to the tooth

(Fig. 5.4D). This results in translation from the simultaneous mesio-palatal rotation of the molar from the activation of the vertical component of the loop and disto-palatal rotation from the twisting of the loop. Furthermore, this is a frictionless approach, which has the potential of moving the teeth more efficiently with a light force, since binding will not occur. To distalize the whole maxillary dentition, a 0.016 × 0.022-in nickel-titanium (NiTi) wire is placed on the lingual brackets of all maxillary teeth. This wire also engages the first molar, which also has the loop activated from the i-station (Fig. 5.5A). In this manner, all teeth except for the first molar initially tip distally, and then are straightened to the correct position by the elastic deflection of the wire based on the position of the first molar.(Fig. 5.5B–C). Another advantage of loop mechanics is the possibility of vertical activation of the horizontal component of the loop to achieve either extrusion or intrusion (Fig. 5.6A). Similarly, the loops can be opened or closed in the transverse dimension to achieve expansion or constriction of the maxillary arch (Fig. 5.6B). As described earlier, the appliance also allows for anteroposterior control of the molars (Fig. 5.6C). Thus this appliance offers three-dimensional control of the maxillary first molars with 6 degrees of freedom and without generating frictional forces (Fig. 5.6D). Consequently, first molar control is paramount for the successful correction of the malocclusion. 

CHAPTER 5  Predictable Management of Molar Three-Dimensional Control with i-station

A

B

C

E

D

F

45

G • Fig. 5.2  i-station components and features. (A) The i-screw has a broad base on the attachment head

which acts as a stop, preventing the i-platform from burying into the mucosa. (B) Only one of the i-screws has a precise fit within the platform, allowing the second i-screw to be placed within a range of positions. (C) The i-screw head and the i-platform hole are both hexagonal. (D) There are two grooves in the i-platform, which can be adjusted to conform to different i-screw angles and heights. (E) The i-arm plate/i-arm square wire can easily be replaced by removing the i-cap. (F) The i-arm plate/i-arm square wire can be attached at different angles (in 45-degree increments) to the flower attachment head of the i-platform. (G) Brackets can be welded to the i-arm plate and beta-titanium wires can be used to create complex force systems.

Mechanics to Apply Labial Crown Torque to the Incisors When labial torque is applied to the maxillary incisors, a simultaneous extrusion force acts on the incisors and an exact equal and opposite force acts on the molars to produce intrusion (Fig. 5.7A). This intrusive force on the molars can be counteracted with i-station loop mechanics, effectively placing labial crown torque on the incisors (Fig. 5.7B). By controlling the first molars, incisors inclination can be thoroughly controlled without any incisor extrusion.

Case 1 A 21-year-old male presented with chief complaint of facial and dental midline deviation and crowded dentition (Fig. 5.8). Extraoral examination revealed mandibular deviation to the left side with an orthognathic soft tissue profile and lower lip protrusion. Intraorally, a midline discrepancy of 9 mm was observed, with the maxillary dental midline deviated 3 mm to the right from the facial midline, while the mandibular dental midline was shifted 6 mm to the

left. Maxillary lateral incisors showed linguoversion. The amount of crowding was approximately 12 mm in maxilla and 6 mm in the mandible. Class I canine and molar relationship on the right and a Class II relationship on the left with minus 1 mm overjet and 0 mm overbite was observed. The panoramic radiograph exhibited vertically impacted maxillary third molars and horizontally embedded mandibular third molars. The lateral cephalometric analysis revealed a skeletal Class III relationship with a retrognathic maxilla and normally positioned mandible. The mandibular plane angle was within the norm (Fig. 5.9). Maxillary incisor inclination was average and the mandibular incisors were lingually inclined, creating an obtuse interincisal angle.

Treatment Plan and Alternatives Orthognathic surgery was recommended because of the mandibular asymmetry and a significant midline discrepancy; however, this treatment option was rejected by the patient. Furthermore, the patient requested for a treatment approach without extractions. To improve the maxillary tooth size-arch length discrepancy and midline deviation to the right, an i-station was planned. The i-station would secure anchorage to distalize the

46 PA RT I I I    Palatal Implants

A

B

C • Fig. 5.3  (A) Theoretical translatory movement of the maxillary dentition. (B) Translatory tooth movement

of the maxillary dentition represented by each tooth having its own center of resistance. (C) High force level increases the risk of mini-implant failure.

right molars 5 mm and the left molars 7 mm, as well as displacing the midline laterally to the left approximately 3 mm. In addition, to improve mandibular tooth size-arch length discrepancy and midline deviation to the left, a mandibular i-station was planned to be used on the right oblique ridge. This anchorage unit would be used to distalize the right molars by 5 mm and move the midline to the right approximately 6 mm. Finally, Class III intermaxillary elastics would distalize the mandibular left molars by 1 mm. 

Treatment Progress Fixed lingual orthodontic appliances were placed on both arches and a 0.016-in NiTi archwire inserted. An i-station was placed in the posterior maxillary midpalatal suture and a mandibular i-station was placed in the mandibular oblique ridge on the right. On the maxilla, four brackets were welded to the i-arm plate. Stainless steel wires (0.047in) were extended posterior to the molars, and distalization of the right and left molars was performed using NiTi closed coils. A 0.047-in stainless steel wire was extended to the left maxillary canine and connected to the right lateral incisor with a NiTi closed coil to move the midline to the left (Fig. 5.10). In the mandible, an i-arm square wire was extended posteriorly and anteriorly to the right first molar, and NiTi closed coils were used to simultaneously perform distalization of

the right first molar and rightward lateral movement of the right lateral incisor. Arch wires were exchanged sequentially from 0.018-in, to 0.016- × 0.022-in, and to 0.018- × 0.025in NiTi dimensions. The i-arm was changed for the next stage of treatment in the maxillary i-station (Fig. 5.11). The maxillary right canine was constricted using an elastic thread from a 0.047in stainless steel wire extended to the right canine. Again, a 0.047-in stainless steel wire was extended to the left canine and connected to the right lateral incisor with a NiTi closed coil to displace the midline to the left. Using 0.032- × 0.032-in beta-titanium wires, right molars were distalized while the left molars were expanded, distalized and rotated distobuccally. Detailing during the finishing phase was performed using 0.018- × 0.025-in beta-titanium wires after the dental and facial midlines aligned and both canine and molar relationships were corrected to Class I. 

Treatment Result The significant amount of crowding was corrected and canine and molar Class I relationships achieved (Fig. 5.12). The 9-mm midline discrepancy improved, with the upper and lower dental midlines matching the facial midline. Preand posttreatment cephalometric superimpositions showed distal movements of 5 mm for the maxillary right molar, 7 mm for the left molar, 4 mm for the mandibular right molar,

CHAPTER 5  Predictable Management of Molar Three-Dimensional Control with i-station

A

47

B

C

D • Fig. 5.4  Comparison of sliding mechanics and loop mechanics. (A) Distalizing force on a lingual tube on the

first molar with an open coil from the mesial side generates a rotational moment and causes distal tipping and binding which suppresses tooth movement. (B) This same principle is observed from an occlusal perspective, where molar rotation occurs with the applied force. (C) In loop mechanics, a vertical loop is inserted from the i-platform to the molar bracket. To offset the molar tipping, the loop is pre-bent to create an uprighting moment. Thus, tipping and uprighting moments are simultaneously generated causing bodily movement of the tooth. (D) From the occlusal perspective, the loop is twisted so a disto-palatal rotation moment is applied. This results in translation. This is a frictionless approach which avoids wire binding.

and 1 mm for the left molar (Fig. 5.13). Treatment results were stable at the 1-year posttreatment visit (Fig. 5.14). 

Case 2 A 26-year-old woman presented for an orthodontic consult with chief complaints of an openbite, lip protrusion, and a retrusive mandible (Fig. 5.15). Extraoral findings revealed perioral muscle tension, which included the chin, and incompetent lips. Lip protrusion as well as convex profile because of a significant retrognathic mandible were noted. Intraoral findings revealed a severe anterior openbite (-9 mm), severe overjet (8 mm), and approximately 8 mm of crowding in the maxilla and 3 mm in the mandible. Canine and molar relationships were Class II. The panoramic radiograph showed microdontia of the maxillary right third molar and missing left third molar, and both mandibular third molars were practically erupted (Fig. 5.16). Also the mandibular condyles were remarkably resorbed bilaterally. Cephalometric analysis indicated that the severe resorption of the mandibular condyles had caused a remarkable shortening of the mandibular ramus, which led to extreme

clockwise rotation of the mandible and consequently an anterior openbite, resulting in a Class II skeletal relationship. The maxillary and mandibular incisal angles showed labial inclination and an acute interincisal angle was present.

Treatment Plan and Alternatives To reduce the magnitude of the severe openbite and the mandibular retrognathism, orthognathic surgery with maxillary impaction and mandibular advancement was the most appropriate treatment strategy. However, performing mandibular advancement surgery with the present condylar condition increased the possibility of further mandibular condylar resorption postsurgically and relapse. Furthermore, the patient was reluctant to undergo surgery. Bilateral extraction of maxillary and mandibular first premolars was also suggested for improvement of lip protrusion and openbite. However, this method is based on extrusion of the anterior teeth, with no improvement in the mandibular anteroposterior and vertical positioning and with potential of relapse in the openbite. The patient also rejected this treatment option, since she was averse to the temporary unesthetic results of premolar extraction therapy.

48 PA RT I I I    Palatal Implants

The final treatment plan was to extract the mandibular third molars and use that space to distalize the mandibular dentition and to extract the maxillary right third molar and distalize the maxillary dentition. These movement were to be performed using i-stations in the maxilla and mandible. Furthermore, to correct the openbite, the maxillary and mandibular molars were to be intruded from the i-stations, in conjunction to intrusion of the mandibular anterior teeth, which would result in a remarkable counterclockwise rotation of the mandible, improving the projection of the chin and reducing the anterior lower facial height. 

A

Treatment Progress The appliances were bonded on the maxillary lingual and mandibular labial sides, and 0.016-in NiTi archwires were inserted. An i-station was implanted in the posterior midpalatal suture and an impression was taken for fabrication of a working cast. Two brackets were welded to the i-arm plate and 0.032- × 0.032-in beta-titanium wires with horizontal and vertical loops were fitted between the i-arm plate and first molar brackets (Fig. 5.17). The fabricated i-arm plate was fixed to the i-platform and activated by opening the vertical loops and constricting the horizontal loops to distalize and intrude the molars simultaneously. Bilateral mandibular i-stations were implanted distal to the mandibular molars and a working cast was made. Bilateral i-arm square wires were extended distal to the canine roots, and helical loops were placed distal to the first molar roots (Fig. 5.18). The fabricated i-arms were screwed to the

B

C

•

Fig. 5.5  Distalization of dentition using loop mechanics. (A) For whole maxillary dentition distalization, a 0.016- × 0.022-in nickel-titanium (NiTi) wire is placed on all maxillary brackets. This wire engages the first molar which also has the loop activated for bodily movement. (B) All teeth except for the first molar tip distally and are straightened by the elastic deflection of the wire. (C) All teeth have been straightened based on the first molar control.

A

B

C

D • Fig. 5.6  Loop mechanics range of movement.  (A) Intrusion and extrusion. (B) Expansion and constriction. (C) Distalization and mesialization. (D) Three-dimensional movement with 6 degrees of freedom.

CHAPTER 5  Predictable Management of Molar Three-Dimensional Control with i-station

A

B

• Fig. 5.7  Mechanics of labial crown torque to the maxillary incisors.  (A) Forces generated when applying

labial crown torque to the incisors. (B) Vertical loop from i-station for molar vertical control while applying labial crown torque to the maxillary incisors.

• Fig. 5.8  Pretreatment extraoral and intraoral photographs, and panoramic radiograph. The maxillary and mandibular midlines are shown by the yellow arrows.

49

50 PA RT I I I    Palatal Implants

Parameter

Norm

SD

Value

∠SNA

81.8

3.1

79.1

∠SNB

78.6

3.1

80.6

∠ANB

3.3

2.7

-1.5

26.3

6.3

30.3 36.7

Mandibular pl. to FH Mandibular pl. to SN U1 to FH IMPA

40.2

4.6

114.3

6.5

109

94.7

7.2

80.7

59

6.7

69

Interincisal angle

129.7

9

140.1

Occlusal pl. to SN

14.2

FMIA

20.2

3.5

Lower lip

1

1

0.5

Upper lip

-2.5

1.5

-3.2

AB to Occlusal plane (Wits)

-5.9

• Fig. 5.9  Pretreatment lateral cephalogram and cephalometric analysis.

•

Fig. 5.10  Maxillary bilateral molar distalization with leftward movement of the midline, and mandibular right molar distalization and rightward midline movement (blue arrows show force vectors). Both movements effected by lever arms extended from i-stations. The yellow arrows show maxillary and mandibular midlines.

CHAPTER 5  Predictable Management of Molar Three-Dimensional Control with i-station

51

• Fig. 5.11  In the maxilla, right canine constriction and midline leftward movement was achieved using lever

arms. Right and left molar distalization, distal rotation and expansion was achieved using loop mechanics. The blue arrows show force vectors and the yellow arrows show maxillary and mandibular midlines.

i-platform3. From these appliances, elastic threads extending from the helical loops and front arms were used to distalize and intrude the first molars and canines. A lingual archwire was installed between the first molars to prevent the first molars from rolling buccally as they were being intruded. 

Treatment Result Lip protrusion was significantly reduced. Mandibular anteroposterior projection and reduction in the lower facial height was achieved, which resulted in significant improvement in the perioral muscular tension and elimination of the lip incompetency (Fig. 5.19). Class I molar and canine relationships with good intercuspation and an ideal overbite were achieved. The superimposition from before and after treatment lateral cephalograms revealed that the maxillary molars were

distalized 9 mm and intruded 5 mm, while the mandibular molars were distalized 8 mm and intruded 2 mm. In addition, the mandibular anterior teeth were intruded 3 mm (Fig. 5.20). Consequently, significant mandibular counterclockwise rotation occurred, resulting in 8 mm forward and 5 mm upward mandibular movement of the chin. In addition, the mandibular condyles did not display further resorption changes. 

Summary The i-station system has great versatility that allows threedimensional tooth movement with 6 degrees of freedom. The i-station can be applied to the correction of any type of malocclusion, including severe crowding, maxillary protrusion, mandibular protrusion, deep bite, and hypodontia. The dental movements can result in significant skeletal

52 PA RT I I I    Palatal Implants

• Fig. 5.12  Posttreatment extraoral, intraoral photographs, and panoramic radiograph.

A

B

• Fig. 5.13  (A) Posttreatment lateral cephalogram. (B) Superimposition. Black, pretreatment; red, posttreatment. Dotted lines, right; solid lines, left.

CHAPTER 5  Predictable Management of Molar Three-Dimensional Control with i-station

• Fig. 5.14  One-year postretention extraoral and intraoral photographs.

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54 PA RT I I I    Palatal Implants

• Fig. 5.15  Pretreatment extraoral and intraoral photographs.

CHAPTER 5  Predictable Management of Molar Three-Dimensional Control with i-station

•

Fig. 5.16 Pretreatment lateral cephalogram, cephalometric analysis, temporo-mandibular joint radiographs and panoramic radiograph.

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56 PA RT I I I    Palatal Implants

• Fig. 5.17  Maxillary bilateral molar distalization and intrusion using loop mechanics. The blue arrows show the direction of the force vectors.

CHAPTER 5  Predictable Management of Molar Three-Dimensional Control with i-station

• Fig. 5.18  Whole mandibular dentition intrusion and distalization using i-stations. The blue arrows show force vectors.

57

• Fig. 5.19  Posttreatment extraoral, intraoral photographs and panoramic radiograph.

•

Fig. 5.20 (A) Posttreatment lateral cephalogram. (B) Superimposition. Black, Pretreatment; red, posttreatment. Maxillary molars distalized 9 mm and intruded 5 mm. Mandibular molars distalized 8 mm and intruded 2 mm. Mandibular incisors intruded 3 mm. Mandibular counterclockwise rotation, causing 8 mm forward and 5 mm upward mandibular movement.

A

B

CHAPTER 5  Predictable Management of Molar Three-Dimensional Control with i-station

effects when the molars are controlled vertically, thus greatly expanding the scope of treatment. This approach allows for orthodontic treatment of patients who in the past could only be treated by orthognathic surgery. The i-station is a powerful adjunct in orthodontics, especially in patients with significant dentofacial deformity and treatment complexity.

References 1. Itsuki Y, Imamura E: A new palatal implant with interchangeable upper units, J Clin Orthod 43:318–323, 2009. 2. Itsuki Y, Imamura E, Sugawara J, Nanda R: A TAD-based system for camouflage treatment of severe skeletal Class III malocclusion, J Clin Orthod 50:401–412, 2016.

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3. Itsuki Y, Imamura E: Multipurpose orthodontic system using palatal implants for solving extremely complex orthodontic problems, J World Fed Orthod 6:80–89, 2017. 4. Itsuki Y, Imamura E, Sugawara J: Temporary anchorage device with interchangeable superstructure for mandibular tooth movement, J World Fed Orthod 2:e19–e29, 2013.

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6

MAPA: The Three-Dimensional MiniImplants-Assisted Palatal Appliances and One-Visit Protocol B. GIULIANO MAINO, LUCA LOMBARDO, GIOVANNA MAINO, EMANUELE PAOLETTO, GIUSEPPE SICILIANI

Introduction Insertion of mini-implants for orthodontic anchorage into the palatal vault is finding ever more applications in the field of dentistry.1–5 This anchorage site is useful for both biomechanical and, especially, anatomic reasons, as there are no roots that could interfere with mini-implants insertion.6–8 Nevertheless, the palate does not present a uniform thickness, varying from individual to individual,9 and great care therefore needs to be taken to analyze the availability of bone to guarantee good primary stability and reliable anchorage.10 In recent years, volumetric tomography and purposedesigned software have enabled the design and construction of templates that allow the available bone to be exploited well, making mini-implants placement safer and more precise.11 These three-dimensional (3D) guides are generally constructed with mini-implants placement in the interradicular spaces in mind, specifically to prevent any damage to tooth roots.12–14 However, we present here a mini-implants insertion guide designed specifically for palatal application. This template is able to ensure not only that mini-implants are placed at the correct depth in the maxillary bone but also that multiple implants are parallel. It is therefore suitable for mini-implants destined for anchorage of removable devices, as well as preformed and tailored appliances used in fixed orthodontics. 

laterolateral teleradiography are comparable to those measured on CBCT scans taken roughly 5 mm from the midsagittal plane.15 Mini-implants are positioned to realize a bicortical anchorage without the risk to damage the roots of the teeth. Lombardo et al. have shown that placement of the mini-implants into both cortical layers markedly reduces the load at the trabecular bone and increases stability.16 The use of CBCT is strictly recommended in all cases of impacted canines, laterally displaced lateral incisors, narrow maxilla, or anatomic abnormalities that may affect the correct insertion of the mini-implants. After scanning, a digital model (stereolithography [STL] files) of the upper arch is superimposed onto the DICOM (Digital Imaging and Communications in Medicine) file (Fig. 6.3) or the lateral X-ray (Fig. 6.4), enabling identification of the most suitable anteroposterior mini-implants placement sites (Fig. 6.5) based on the width and thickness of the palatal vault. This operation is performed using suitable software (eXam Vision software integrated with Rhinoceros software), which is also used to design a virtual surgical guide to fit the morphology of the palate and the teeth in the lateral and posterior sectors of the upper arch

Surgical Guide Fabrication The optimal site and direction of mini-implants insertion can be identified on a cone beam computed tomography (CBCT) scan of the maxillary bone (Fig. 6.1) or lateral teleradiography acquired after intraoral positioning of a thermoplastic polyethylene terephthalate-glycol (PET-G) bite, cast on the patient’s plaster model and featuring a series of radioopaque markers along the medial palatine raphe (Fig. 6.2). According to Kim et  al., palatal thicknesses measured via

• Fig. 6.1  Digital Imaging and COmunication in Medicine (DICOM) le of the cone-beam computed tomography scan with the digital mini-implants.

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62 PA RT I I I    Palatal Implants

(Fig. 6.6). The virtual guide can be reproduced in resin (compatible for intraoral use) using a 3D printer (Everes Uno, SISMA S.p.A.), and it is also designed to feature two cylindrical metallic guides, designed to replicate the angle of insertion and prevent the mini-implants from penetrating beyond the required depth, in the central portion (Fig. 6.7). 

Mini-implants Application After local anesthesia to the palatal site in question (2% lidocaine), the surgical guide is fitted, making sure that it rests on the occlusal surfaces of the posterior teeth (Fig. 6.8). If required, a small amount of light-cure resin (Triad by Dentsply) can be used to bond this to the occlusal surfaces of the first premolars. Self-drilling mini-implants (Spider screw Regular Plus and Konic Plus by HDC) of the programmed length and diameter are selected, picked up with the apposite driver— mounted on a low-velocity contra-angle handpiece (30 rpm)—and by these means inserted through the apposite metallic cylinder of the template. Indeed, the guide is able to replicate with extreme precision the transmucosal portion of the mini-implants and driver, and can prevent the miniimplants exceeding the preprogrammed depth (Fig. 6.9). 

Appliance Fabrication STL is used to obtain a model of the maxillary arch, reproducing the heads of two, three, or four mini-implants from the STL file of the digital model. The printed 3D model is then duplicated in a plaster model (Fig. 6.10), metal abutments designed to fit over the heads of the mini-implants are positioned into the plaster, and different kinds of orthodontic appliances can be created. The precision currently achieved by the mini-implants insertion guide designed specifically for palatal application (MAPA) system allows the clinician to apply the mini-implants through the surgical guide and subsequently to apply the orthodontic appliance during the same session without the need to make new impressions.17 Once the appliance has been positioned on K2 Spider screw or Konic Spider Screw (in case the inserted mini-implants are not parallel for anatomic reasons), it is locked by means of a mini-implants fitted with an appropriate driver (Fig. 6.11). 

Clinical Cases The MAPA system is very versatile and is used to treat different types of malocclusion (Class III, Class II, narrow maxilla, and asymmetric cases).

Class III Growing Patients One of the most challenging orthodontic treatments to perform is the correction of skeletal Class III malocclusion,18 since a potentially unfavorable growth pattern usually requires early intervention to be effective.19 However, early treatment using a protraction facemask in conjunction with a rapid palatal expansion (RPE) appliance has proven successful in correcting skeletal Class III malocclusions that are caused primarily by deficient maxillary development.20,21 The goal of facemask therapy is to obtain purely skeletal changes with minimal effects on the dentition.22 Previous studies have shown that these undesirable side effects, which include excessive forward movement and extrusion of the maxillary molars, excessive proinclination of the maxillary incisors, and an increase in lower face height, can easily result from tooth-borne protraction facemask therapy,23–25 a particular concern in situations in which preservation of arch length is necessary.22 To simplify the procedure for the treatment of Class III patients, Maino et al.26,27 developed a 3D surgical guide to provide a safe and reliable palatal miniimplants insertion. The associated protocol that proposed alternating expansion and compression of the maxillary complex28 by means of a hybrid palatal expander, anchored to both the bone and the teeth, to be followed by 4 months of facemask therapy in a sample of 28 growing Class III patients, has resulted in interesting clinical findings29 (Figs. 6.12 and 6.13). Point A advanced by a mean of 3.4 mm with respect to the reference plane Vert–T. The mandibular plane rotated clockwise, improving the angle between points A, Nasion, and point B (ANB) (+3.41 degrees) and the Wits index (+4.92 mm). The upper molar displayed slight extrusion (0.42 mm) and mesialization (0.87 mm). The cephalometric analysis results were very similar to those reported in the metaanalysis of three randomized controlled trials conducted by Cordasco,30 in terms of both sagittal (angle between

• Fig. 6.2  X-ray and lateral cephalogram showing radio-opaque markers along the medial palatine raphe with the digital mini-implants. Digital model cast and the vacuum-formed retainer with the markers.

CHAPTER 6  MAPA: The Three-Dimensional Mini-Implants-Assisted Palatal Appliances and One-Visit Protocol

•

Fig. 6.3  Superimposition of the digital model with mini-implants on cone-beam computed tomography. (With permission from HDC.)

63

• Fig. 6.4  Superimposition of the digital model with mini-implants on lateral cephalograms.

• Fig. 6.5  Stereolithography model and ideal mini-implants insertion point (IIPS).

• Fig. 6.6  The three-dimensional surgical guide resting on the occlusal

• Fig. 6.7  The three-dimensional printed surgical guide.

surface of the posterior teeth.

points S, N, and A [SNA], angle between points S, N, and B [SNB], and ANB) and vertical (angle between cranial base plane SN and palatal plane PP [SN-PP] and angle between cranial base plane SN and mandibular plane MP [SN-MP]) measurements. However, it should be noted that the mean duration of treatment in the articles cited by Cordasco was roughly 1 year, whereas ours was completed in 4 months.

Moreover, the mean age of our sample was considerably greater (11 years 4 months vs. 8 years 5 months). 

Class II Patient Maxillary molar’s distalization represents an orthodontic procedure frequently required in patients with Class II

64 PA RT I I I    Palatal Implants

malocclusion. Patient cooperation is one the most important aspect every clinician must face,27 and unavoidably, it tends to decrease,29–33 making treatment with extraoral and intraoral appliances unpredictable.34 To facilitate this procedure, a wide range of distalizing devices have been developed and several more have been designed over the years. The growing demand for orthodontic treatment methods requiring minimal cooperation but maximum anchorage control has led clinicians to search for “bone-supported anchorage.” After years of research, mini-implants, as a temporary

anchorage device, have been recognized as a valuable tool because of their small size, ease of insertion and removal, low cost, immediate loading, and ability to be safely inserted in different locations. The MAPA system can be used to ensure a skeletal anchorage to a sliding device on pistons with nickel-titanium springs. The new digital technologies today allow these devices to be built using laser metal fusion procedures (Mysint 100, SISMA S.p.A.) (Fig. 6.14). This appliance design eliminates anchorage loss risks and minimizes the need for the clinician to perform complex procedures until Class I molar relationship is reached. In Class II patients requiring a first phase of expansion of the upper maxilla and then a distal rotation of the first upper molars, it is possible to use the combination of two different skeletal anchorage devices. For example, it is possible to first place two K2 spider screws (9 and 11 mm) on the palate and subsequently cement a hybrid rapid expander (Fig. 6.15). Once the expansion is achieved, a new impression is realized

• Fig. 6.8  The three-dimensional printed surgical guide in the patient mouth.

•

Fig. 6.9  The mini-implants position after three-dimensional surgical guide removal.

•

Fig. 6.11  K2 Regular Plus Spider Screw or Konic Spider Screw (in case the inserted mini-implants are not parallel for anatomic reasons), the abutment, and the mini-implants used to fix the appliances.

• Fig. 6.10  Three different examples of printed digital model cast with inserted mini-implants.

CHAPTER 6  MAPA: The Three-Dimensional Mini-Implants-Assisted Palatal Appliances and One-Visit Protocol

and a pendulum is built without the need to insert new mini-implants. By the pendulum, a super Class I molar relationship is achieved and then a fixed straight wire multibrackets fixture is used for the space closure, alignment, and coordination of the arches. 

Narrow Maxilla For many years surgically assisted rapid palatal expansion (SARPE) has been the treatment of choice to resolve the

65

maxillary constriction in young adults, although several authors have reported successful nonsurgical expansion in young and adult patients.31–35 Nevertheless, in 2010, Lee et  al.36 introduced an expansion appliance secured to the palate by means of mini-implants, the MARPE (miniimplants-assisted rapid palatal expander), which used to treat a 20-year-old patient with severe transverse discrepancy before orthognathic surgery for mandibular prognathism. Expansion was successfully achieved with minimal damage to the teeth and periodontium.

• Fig. 6.12  Intraoral photos of a Class III patient before and after hybrid rapid palatal expansion and face mask protocol.

•

Fig. 6.13 Cephalometric analysis of the Class III patient before and after hybrid rapid palatal expansion and face mask protocol.

66 PA RT I I I    Palatal Implants

•

Fig. 6.14  Records of a Class II patient treated by a sliding distalizing appliance fixed on palatal miniimplants and upper first premolars.

• Fig. 6.15  Records of a Class II patient treated by a hybrid rapid palatal expander and a pendulum appliance fixed on palatal mini-implants.

CHAPTER 6  MAPA: The Three-Dimensional Mini-Implants-Assisted Palatal Appliances and One-Visit Protocol

In a 16-year-old female presenting with a hyperdivergent face, a gummy smile, an anterior openbite, narrow maxilla, and a crossbite on the left side (Fig. 6.16), preliminary expansion of the upper arch was advised before any orthodontic intervention. To avoid periodontal complications during palatal expansion, we offered the patient a BBRME (Bone Born Rapid Palatal Expansion). CBCT images were used to plan the virtual insertion of two selftapping, self-drilling Spider Screw Regular Plus† miniimplants (11 mm long, 2 mm in diameter) in the paramedian areas at the level of the first premolars (see Fig. 6.16). Two similar mini-implants were then virtually inserted between the second premolars and first molars on each side, with a divergent inclination to maximize bony support (see Fig. 6.9). With the patient under local anesthesia, the four mini-implants were mounted using a lowspeed contra-angle handpiece (50 rpm) and directed through the custom-designed guide sleeves of the insertion stent, precisely positioning them in the palate. The BBRME was attached immediately by connecting it to the anterior mini-implants through two abutments embedded in the acrylic and fixed by mini-implants (Fig. 6.17). The two posterior abutments were attached to the posterior miniimplants through predrilled holes in the acrylic portion of the appliance. These two abutments were then affixed to the body of the BBRME using a small amount of flowable light-cured composite. The expander was activated under a protocol of three quarter-turns per day to determine whether the BBRME would show immediate results; if not, SARPE would be required. After 6 days of activation, a small diastema had appeared. Activation was completed in

14 days (see Fig. 6.17). Because the transverse dimension had not been completely corrected, however, a new BBRME was constructed from an impression taken over the four mini-implants after the first device was removed (see Fig. 6.17). Twelve days after activation of the second BBRME, sufficient overcorrection of the transverse diameter had been achieved. CBCT performed after expansion demonstrated the skeletal effects of the appliance (Fig. 6.18). In adult patients, the maxillary suture opening is more difficult to be realized and conventional rapid palatal expanders can fail. To achieve a more parallel and reliable suture opening and overcome some anatomic impairments because of the narrow palatal vault, a Tandem Skeletal Expander (TSE) is usually constructed (Fig. 6.19). After four mini-implants (Spider screw K2) insertion on the maxillary bone according to MAPA system, two expanding mini-implants are positioned to be active simultaneously. The CBCT scan 3D reconstruction made after the expansion showed a considerable maxillary suture opening of about 6 mm. 

Asymmetrical Cases MAPA system is also useful in cases requesting asymmetrical biomechanics. The bicortical anchorage of two palatal ­mini-implants can be used in a different way in the right and left side. For example, on the right side a Pendulum spring is used to distalize the upper molar, while the on left side a metallic arm was used to move canine, premolar and molar on the palatal side to achieve a more negative torque and correct the transversal problem (Fig. 6.20). 

• Fig. 6.16  Frontal initial intraoral photo and cone-beam computed tomography-stereolithography model cast. Digital mini-implants superimposition.

•

67

Fig. 6.17  First and second rapid palatal expander applied to four palatal mini-implants to achieve the correct maxillary expansion.

68 PA RT I I I    Palatal Implants

• Fig. 6.18  Frontal intraoral photo after the end of the expansion and after/before cone-beam computed tomography superimposition.

• Fig. 6.19  Before and after occlusal intraoral photos and after expansion cone-beam computed tomog-

raphy of an adult patient with severe narrow maxilla treated by Tandem Skeletal Appliance (TSA). (With permission from HDC.)

• Fig. 6.20  Intraoral occlusal photos and digital model casts of an asymmetric patient treated to distalize upper right molars and to lingually upper second premolars and molars. (With permission from HDC.)

Conclusion MAPA system represents a reliable and safe way to position two or more mini-implants on the maxillary bone in growing or adult patient. Endless combinations are possible, and

according to the biomechanics needs, maxillary bone protraction, upper molar distalization, maxilla expansion, upper teeth mesialization, intrusion or lingual inclination can be realized without the need for compliance and risks of anchorage loss.

CHAPTER 6  MAPA: The Three-Dimensional Mini-Implants-Assisted Palatal Appliances and One-Visit Protocol

References 1. Lee J, Miyazawa K, Tabuchi M, Kawaguchi M, Shibata M, Goto S: Midpalatal miniscrews and high-pull headgear for anteroposterior and vertical anchorage control: cephalometric comparisons of treatment changes, Am J Orthod Dentofacial Orthop 144(2):238–250, 2013. 2. Suzuki EY, Suzuki B: Maxillary molar distalization with the indirect Palatal miniscrew for Anchorage and Distalization Appliance (iPANDA), Orthodontics (Chic.) 14(1), 2013. 3. Kim KB, Helmkamp ME: implant-supported rapid maxillary expansion, J Clin Orthod 46(10):608–612, 2012. 4. Razavi MR: Molar intrusion using miniscrew palatal anchorage, J Clin Orthod 46(8):493–498, 2012. 5. Kang YG, Kim JY, Nam JH: Control of maxillary dentition with 2 midpalatal orthodontic miniscrews, Am J Orthod Dentofacial Orthop 140(6):879–885, 2011. 6. Deguchi T, Nasu M, Murakami K, Yabuuchi T, Kamioka H, Takano-Yamamoto T: Quantitative evaluation of cortical bone thickness with computed to-mographic scanning for orthodontic implants, Am J Orthod Dentofacial Orthop 129, 721.e7-12, 2006. 7. Poggio PM, Incorvati C, Velo S, Carano A: “Safe zones”: a guide for miniscrew positioning in the maxillary and mandibular arch, Angle Orthod. 76:191–197, 2006. 8. Choi JH, Yu HS, Lee KJ, Park YC: Three-dimensional evaluation of maxillary anterior alveolar bone for optimal placement of miniscrew implants, Korean J Orthod 44(2):54–61, 2014. 9. Gracco L, Lombardo M, Cozzani G, Siciliani: Quantitative conebeam computed tomography evaluation of palatal bone thickness for orthodontic miniscrew placement, Am J Orthod Dentofacial Orthop 134:361–369, 2008. 10. Ludwig B, Glasl B, Bowman SJ, Wilmes B, Kinzinger GS, Lisson JA: Anatomical guidelines for miniscrew insertion: palatal sites, J Clin Orthod 45(8):433–441, 2011. 11. Kitai N, yasuda Y, Takada K: A stent fabricated on a selectively colored stereo lithographic model for placement of orthodontic miniimplants, Int J Adult Orthodon Orthognath Surg 17:264– 266, 2002. 12. Miyazawa Ken, Kawaguchi Misuzu, Tabuchi Masako, Shigemi Goto: Accurate presurgical determination for self-drilling miniscrew implant placement using surgical guides and cone-beam computed tomography, Eur J Orthod 32(6):735–740, 2010. 13. Kim SH, Choi YS, Hwang EH, Chung KR, Kook YA, Nelson G: Surgical positioning of orthodontic mini-implants with guides fabricated on models replicated with cone-beam computed tomography, Am J Orthod Dentofacial Orthop 131:S82–S89, 2007. 14. Hong L, Dong-xu L, Guangchun W, Chun-ling W, Zhen Z: Accuracy of surgical positioning of orthodontic miniscrews with a computer-aided design and manufacturing template, Am J Orthod Dentofacial Orthop 137:728, 2010. 15. Young-Jae K, Sung-Hoon L, Sung-Nam G: Comparison of cephalometric measurements and cone-beam computed tomographybased measurements of palatal bone thickness, Am J Orthod Dentofacial Orthop 145:165–172, 2014. 16. Lombardo L, Gracco A, Zampini F, Stefanoni F, Mollica F: Optimal palatal configuration for miniscrew applications, Angle Orthod 80(1):145–152, 2010. 17. Maino BG, Paoletto E, Lombardo L, Siciliani G: From planning to delivery of a bone-borne rapid maxillary expander in one visit, J Clin Orthod 51(4):198–207, 2017.

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18. Ngan P, Yiu C, Hu A, Hagg U, Wei SH, Gunel E: Cephalometric and occlusal changes following maxillary expansion and protraction, Eur J Orthod 20:237–254, 1998. 19. Baccetti T, Franchi L, McNamara Jr JA: Growth in the untreated Class III subject, Semin Orthod 13:130–142, 2007. 20. Ngan PW, Hagg U, Yiu C, Wei SHY: Treatment response and long-term dentofacial adaptations to maxillary expansion and protraction, Semin Orthod 4:255–264, 1997. 21. Baccetti T, Franchi L, McNamara Jr JA: Treatment and posttreatment craniofacial changes after rapid maxillary expansion and facemask therapy, Am J Orthod Dentofac Orthop 118:404– 413, 2000. 22. Hagg U, Tse A, Bendeus M, Rabie BM: Long-term follow-up of early treatment with reverse headgear, Eur J Orthod 25:95–102, 2003. 23. Lertpitayakun P, Miyajima K, Kanomi R, Sinha PK: Cephalometric changes after long-term early treatment with facemask and maxillary intraoral appliance therapy, Semin Orthod 7:169–179, 2001. 24. Delaire J: Maxillary development revisited: relevance to the orthopaedic treatment of class III malocclusions, Eur J Orthod 19:289–311, 1997. 25. Da Silva Filho OG, Magro AC, Capelozza FL: Early treatment of the class III malocclusion with rapid maxillary expansion and maxillary protraction, Am J Orthod Dentofac Orthop 113(2):196– 203, 1998. 26. Maino G, Paoletto E, Lombardo L, Siciliani G: MAPA: a New High-precision 3D method of Palatal mini- screw Placement, Eur J Clin Orthod 3:41–47, 2015. 27. Maino G, Paoletto E, Lombardo L, Siciliani G: A three-dimensional digital insertion guide for palatal miniscrew placement, J Clin Orthod 50(1):12–22, 2016. 28. Liou EJ: Effective maxillary orthopedic protraction for growing Class III patients: a clinical application simulates distraction osteogenesis, Prog Orthod 6:154–171, 2005. 29. Maino G, Turci Y, Arreghini A, Paoletto E, Siciliani G, Lombardo L: Skeletal and dentoalveolar effects of hybrid rapid palatal expansion and facemask treatment in growing skeletal Class III patients, Am J Orthod Dentofacial Orthop 153:262–268, 2018. 30. Cordasco G, Matarese G, Rustico L, et al.: Efficacy of orthopedic treatment with protraction facemask on skeletal Class III malocclusion: a systematic review and meta-analysis, Orthod Craniofac Res 17:133–143, 2014. 31. Brunelle JA, Bhat M, Lipton JA: Prevalence and distribution of selected occlusal characteristics in the US population, 19881991, J Dent Res 75(Spec No):706–713, 1996. 32. Shetty V, Caridad JM, Caputo AA, Chaconas SJ: Biomechanical rationale for surgical-orthodontic expansion of the adult maxilla, J Oral Maxillofac Surg 52:742–749, 1994. 33. Stuart DA, Wiltshire WA: Rapid palatal expansion in the young adult: time for a paradigm shift? J Can Dent Assoc 69:374–377, 2003. 34. Handelman CS, Wang L, BeGole EA, Haas AJ: Nonsurgical rapid maxillary expansion in adults: report on 47 cases using the Haas expander, Angle Orthod 70:129–144, 2000. 35. Capelozza Filho L, Cardoso Neto J, da Silva Filho OG, Ursi WJ: Non-surgically assisted rapid maxillary expansion in adults, Int J Adult Orthodon Orthognath Surg 11:57–66, 1996. 36. Lee KJ, Park YC, Park JY, Hwang WS: Miniscrew-assisted nonsurgical palatal expansion before orthognathic surgery for a patient with severe mandibular prognathism, Am J Orthod Dentofacial Orthop 137(6):830–839, 2010.

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7

Asymmetric Noncompliance Upper Molar Distalization in Aligner Treatment Using Palatal TADs and the Beneslider BENEDICT WILMES, SIVABALAN VASUDAVAN

Upper Distalization in Aligner Treatment Class II malocclusions are frequently encountered in orthodontic practice, with a prevalence of approximately 15%. The distalization of the maxillary first permanent molar teeth may be considered as a viable treatment option for patients presenting with an Angle Class II malocclusion characterized with an increased overjet and anterior crowding. Molar distalization can be performed using intraoral or extraoral appliances. Potential issues arising with patient compliance may be associated with the prolonged use of headgear.1,2 There has been an increasing trend in the clinical use of purely intraoral appliances that require minimal need for patient cooperation. Unfortunately, most of the conventional devices for noncompliance upper molar distalization produce unwanted side effects, such as anchorage loss.3 Most tooth-borne appliances for upper molar distalization produce an unwanted side effect of anchorage loss resulting in maxillary incisor proclination, reported to be 24% to 55 % of observed tooth movement.3–5 In clinical cases requiring unilateral distalization, a midline shift of the anterior teeth is commonly observed. One possibility to reduce unwanted orthodontic effects of reciprocal forces is the usage of a palatal acrylic pad or Nance button. However, the anchorage stability of these soft-tissue-borne elements is not always certain. Moreover, oral hygiene is often impaired because of the partial coverage of the palatal area. To minimize anchorage loss, mini-implants have been incorporated into the design of maxillary distalization appliances.6–16 Mini-implants can be positioned intraorally with minimal degrees of surgical invasiveness, are readily integrated with concomitant biomechanical initiatives, and are relatively cost effective.16–22 An increasing number of patients seek orthodontic treatment with sequential plastic aligner therapy. Pure bodily

tooth movement with sequential plastic aligner therapy is challenging to achieve to a high degree of predictability. As a consequence, unilateral or bilateral molar distalization is limited when relying on aligner movement alone. While there are limited reports of successful upper molar distalization of up to 2.5 mm in the literature, a very long treatment time and high level of patient compliance are expected with requirement for intermaxillary Class II elastics to be worn during the long period of the sequential upper molar distalization.23–25 Moreover, the potential side effects of Class II elastics must be considered in terms of mesial shift of the lower anchorage teeth; this might be a severe problem, especially in unilateral Class II elastics applications with the potential for development of a lower midline shift, maxillary arch rotation and a yaw discrepancy, and transverse occlusal canting. 

Optimal Insertion Sites for Mini-Implants Various iterations of implant-supported distalization appliances have been published recently. The retromolar region is an unsuitable area for mini-implant insertion because of the unfavorable anatomic conditions (poor bone quality and thick soft tissue).26 In addition, the alveolar process has also been shown to be inappropriate in cases of a desired molar distalization, since the mini-implants are in the direct path of the moving teeth, resulting in a failure rate that is much higher compared to the anterior palate.26,27 Therefore the palatal area posterior from the rugae (Fig. 7.1, T-Zone28) seems to be the preferred insertion site for mini-implants where the treatment objective is for distal movement of the maxillary first permanent molar without associated anchorage loss and maxillary incisor displacement. Furthermore, good bone quality with thin attached mucosa 71

72 PA RT I I I    Palatal Implants

• Fig. 7.1  T-Zone palatal posterior from the rugae seems to be the optimum TAD insertion site for distalization of molars in the maxilla. Within the T-Zone, mini-implants can be inserted in a median or paramedian fashion.

implies minimal risk of tooth-root injuries and a very high success rate in the anterior palatal region.29 In contrast to treatment strategies involving the interradicular positioning of mini-implants, the molar teeth can be distalized and the premolars are free to move distally because of the stretch of the interdental fibers without any interference, since the palatally positioned mini-implants are not in the path of moving teeth. Within the T-Zone, the mini-implants can be inserted in a median or paramedian orientation,28 with both insertion sites showing a similar stability.30 

Clinical Procedure and Rationale of the Beneslider The Beneslider (Fig. 7.2)20,31–33 is a maxillary molar tooth distalization appliance, principally designed on the use of one or two mini-implants coupled in a median or paramedian orientation in the anterior palate. Mini-implants with exchangeable abutments are indicated (see Fig. 7.2B) with the goal to achieve a stable and safe connection between the mini-implants and the distalization mechanics. Following the application of local or topical anesthesia in the anterior hard palate, the mini-implants are inserted usually without the need for predrilling of bone. It is advisable to choose mini-implants with a diameter of 2 or 2.3 mm, since they provide a superior stability.34–37 An adult patient will typically present with areas of higher bone density in the anterior hard palate, and require a preparatory step of drilling a pilot hole to an approximate depth of 2 to 3 mm to be performed to keep the insertion torque within a safe range.34 Predrilling can be performed using a handpiece that is adapted to a regular contra angle, without the need for cooling. The Benefit mini-implant31–33,38 abutments (see Fig. 7.2B) can be secured with the use of an inner mini-implants or fixation cap. If a single mini-implant is used, one abutment is fixed for the distalization mechanics. To increase the stability and prevent a rotational tendency leading to loosening, two Benefit mini-implants can be coupled with the Beneplate32 (see Fig. 7.2C). To secure the Beneplate, a small fixation

screw is used. Both abutments as well as Beneplates are available with 1.1-mm stainless steel wire configuration (see Fig. 7.2B and C). Depending on the axis and the location of the two positioned mini-implants, the Beneplate framework requires adjustment. By modifying the angulation of the 1.1 mm SS wire, it is possible to achieve a simultaneous intrusion or extrusion of the molars.39–41 The distalization force is delivered by two springs (usually 240-g) activated by two locks (see Fig. 7.2A). At the same appointment, stainless steel bands with lingual sheaths are adapted to the maxillary molar teeth. These springs are pushing the sliding tubes (see Fig. 7.2D) into the lingual sheaths of the molar bands. It seems advantageous that the Beneslider appliance can be fitted directly without the requirement for adjunctive laboratory work in terms of welding or soldering, or the need to record an intraoral impression. Alternatively, the clinician has the choice to record an intraoral impression and transfer the clinical setup to a plaster cast model using an impression cap and laboratory analogue from the Benefit system.

How to Combine Beneslider and Aligners, Strategies and Clinical Tips If sequential plastic aligners are to be used to realize the planned tooth movement, we recommend the use of bonded tubes (see Fig. 7.2E) instead of bands, sheaths, or welded tubes (see Fig. 7.2A and D). The primary advantages of a bonded tube are esthetics, and the adaptability, accuracy, and fit of the aligners are not undermined by the presence of stainless steel molar bands. The aligner material could cover this bonded connection (Fig. 7.3A), or the aligner could be cut out in this connection area (Fig. 7.3B). Following distalization of the maxillary molar teeth, steel ligatures can be used (see Fig. 7.3A) or springs removed (see Fig. 7.3B) to modify the Beneslider from an active distalization device to a passive molar anchorage device. The primary objective is to stabilize the maxillary molar teeth during the retraction of the maxillary anterior teeth. Our experience in using the Beneslider appliance in conjunction with aligners commenced with a two-phase approach39: the initial phase involving molar distalization, and the secondary phase for the final detailing of the occlusion with sequential plastic aligners. With a two-phase approach, an impression (or scan) is recorded after distalization (Fig. 7.3C). To reduce the total treatment time, we now recommend simultaneous distalization with the Beneslider and alignment with sequential plastic aligners. With a single-phase approach, the impressions for aligners are taken before distalization of the maxillary molar teeth and the anticipated tooth movement to be produced by the Beneslider appliance is programmed in the digital software platform. According to our clinical findings, a sequential step-by-step distalization is not required (ClinCheck, Align Technology). The entire maxillary dental arch can

CHAPTER 7  Asymmetric Noncompliance Upper Molar Distalization in Aligner Treatment Using Palatal TADs and the Beneslider

A

73

B

C

D

E • Fig. 7.2  The Beneslider appliance (A) is based on one or two mini-implants with exchangeable abut-

ments (B). On top of the mini-implants, abutments and miniplates (C) can be fixed. For median paramedian mini-implants, Beneplates with a wire parallel with the plate is used (long and short); for paramedian mini-implants, Beneplates with a wire perpendicular with the plate is used (long and short). The distalization force is delivered by springs and activated by two activation locks (A). Sliding tubes (D) can be stuck in lingual sheaths of upper molars, or tubes (E) can be bonded to the palatal surface. (With permission from PSM Medical Solutions.)

be distalized simultaneously because of the absolute molar anchorage provided by the Benefit appliance; the stretch of the interdental fibers supports the simultaneous distal drift of maxillary anterior teeth. If the sequential plastic aligner material covered the connection area with the molars (see Fig. 7.3A), the impressions for aligners should be recorded following the fitting and insertion of the Beneslider appliance. The Beneslider should not be activated before the delivery of the aligners. If the aligners have a cut out area (see Fig. 7.3B, Invisalign: “Button cut out”), the impressions for aligners are able to be recorded either before or after insertion of the Beneslider appliance. Distalization forces can be applied to the first (see Fig. 7.3A left) or second (see Fig. 7.3B right) maxillary molar teeth. Our clinical experiences have shown that force application to the first molar is a superior approach, as

direct force application to the second molar teeth is associated with precocious distalization of the second molars leading to improper tracking and fitting of the sequential plastic aligners; a risk that is reduced if the maxillary first molar teeth are connected to the Beneslider. 

Clinical Case 1: Simultaneous Start of Aligner and Distalization A 33-year-old male patient presented seeking orthodontic care to resolve an Angle Class II Division I subdivision righthand-side malocclusion, characterized by anterior crowding, and a maxillary midline deviated to the left (Fig. 7.4, Table 7.1). The maxillary lateral incisor teeth were migrated mesially to the right side resulting in an asymmetric maxillary dental arch and an arch-length insufficiency for alignment of

74 PA RT I I I    Palatal Implants

the maxillary right canine. The patient specifically requested an invisible orthodontic treatment option, to be performed on a nonextraction basis. Following the insertion of two Benefit mini-implants in the anterior palate (Fig. 7.5A), the Beneslider appliance was passively installed (Fig. 7.5B, the spring is not activated) and the impressions were recorded for fabrication of clear sequential plastic aligners (Orthocaps, Hamm, Germany). The aligner manufacturer was instructed to design the aligners in such way that the aligner material covered the connection area (Fig. 7.6A). After delivery and insertion of the aligners, the Beneslider was activated by pushing the 240-g nickel-titanium (NiTi) springs distally using the activation lock (Fig. 7.6B). In the first quadrant, the maxillary molars were to be distalized approximately 6 mm, and in the second quadrant only 1 to 2 mm. The patient reportedly adapted to the appliance without issue. The panoramic radiograph denotes bodily distalization of all maxillary posterior teeth after 5 months (Fig. 7.7). Minor interdental spaces were noted in the maxillary arch (Fig. 7.8); this may have happened because of inadequate wear of the aligners or the use of an excessive distalization force resulting in precocious distalization of the maxillary molar teeth. The patient was encouraged to commit to the appropriate period of wearing the aligner, and the rate of molar distalization was reduced. After 14 months of treatment, the maxillary

molar teeth were distalized into an Angle Class I occlusion, and a steel ligature was used between the bonded tube and the activation lock to deactivate the Beneslider (Fig. 7.9). The Beneslider was converted from a distalization device to a molar anchorage device. For the final finishing phase, absolute anchorage to stabilize the maxillary molar was no longer required and the Beneslider appliance was removed (Fig. 7.10). Comprehensive treatment was completed after 18 months (Fig. 7.11), and the palatal mini-implants were removed without the adjunctive use of local anesthesia. 

Clinical Case 2: Aligner Start During Distalization A 41-year-old female patient presented with an Angle Class II division 1 subdivision left-hand-side malocclusion, characterized by anterior arch crowding (Fig. 7.12 and Table 7.2). The maxillary posterior teeth were noted to be mesially positioned on the left side, resulting in an asymmetric maxillary dental arch, with insufficient arch length for the alignment of the maxillary left canine. The patient specifically requested an invisible orthodontic treatment option, to be performed on a nonextraction basis. After insertion of two Benefit mini-implants in the anterior palate, a Beneslider appliance was adapted for the appliance. Given the

A

B

C • Fig. 7.3  The aligners can cover the bonded connection (A) or the aligners can be cut out in this connection area (B). After distalization, steel ligatures are used (A) or the springs are removed (B). Wax should be used for a silicone impression (C). (With permission from PSM Medical Solutions.)

A

B

C

E

D • Fig. 7.4  A 33-year-old male patient with an Angle Class II Division I subdivision right-hand-side malocclusion, characterized by anterior crowding, and a midline shift to the left side.

76 PA RT I I I    Palatal Implants

TABLE   Case 1, Cephalometric Summary 7.1 

Pretreatment

Posttreatment

NSBa

123.9 degrees

124.5 degrees

NL-NSL

7.9 degrees

6.3 degrees

ML-NSL

35.0 degrees

38.3 degrees

ML-NL

27.2 degrees

32.1 degrees

SNA

80.5 degrees

78.5 degrees

SNB

76.2 degrees

74.0 degrees

ANB

4.3 degrees

4.6 degrees

Wits

3.7 mm

2.6 mm

U1-NL

117.6 degrees

106.6 degrees

L1-ML

93.3 degrees

94.5 degrees

U1-L1

121.9 degrees

126.8 degrees

Overjet

6.1 mm

3.9 mm

Overbite

2.0 mm

1.6 mm

A

significant amount of distal movement of the maxillary left molar teeth required, an additional tube was used to support the bodily distalization of the maxillary left first premolar tooth (Fig. 7.13). Treatment commenced with the Beneslider being activated by compressing the lock on to the 240-g NiTi spring. In the second quadrant, the molars were to be distalized approximately 7 mm, in the first quadrant only 2 to 3 mm. After seven months of distalization, several small interdental spaces were visible in between the maxillary left lateral teeth, and an elastic chain was added for retraction of the upper left canine (Fig. 7.14). The panoramic radiograph denotes bodily distalization of all upper lateral teeth. Subsequently, impressions were recorded for fabrication of clear sequential plastic aligners (Invisalign, San Jose, United States). The aligner manufacturer was instructed to design and construct the aligners in such way that the aligner material covered the connection area on the palatal side of the molar (Fig. 7.15). After 16 months of treatment with the Beneslider appliance, the second right molar was distalized into a Class I occlusion and a steel ligature was used between the bonded tube and the activation lock to deactivate the Beneslider in the first

B • Fig. 7.5  After insertion of two Benefit mini-implants in the anterior palate (A) and installation of the Beneslider mechanics (B).

A

B

• Fig. 7.6  (A, B) The aligners are covering the connection areas (Beneslider with the molars). (With permission from Ortho Caps GmbH.)

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77

A

B

• Fig. 7.7  OPG (A) and Cephalogram (B) after 5 months of treatment. (With permission from Ortho Caps GmbH.)

A

• Fig. 7.8  Interdental spacing noted after 10 months. (With permission from Ortho Caps GmbH.)

B

• Fig. 7.9  After 14 months of treatment, the molars were distalized into a Class I occlusion and a steel ligature was used between the bonded tube and the activation lock to deactivate the Beneslider (upper jaw without aligner [A] and with aligner [B]). (With permission from Ortho Caps GmbH.)

78 PA RT I I I    Palatal Implants

• Fig. 7.10  After removal of the Beneslider appliance.

A

B

C

D

• Fig. 7.11 Treatment result after 18 months. Intraoral pictures (A), radiographs (B, C), and patient front view (D).

CHAPTER 7  Asymmetric Noncompliance Upper Molar Distalization in Aligner Treatment Using Palatal TADs and the Beneslider

A

B

C • Fig. 7.12  A 41-year-old female patient with an Angle Class II Division I subdivision left-hand-side malocclusion, characterized by anterior arch crowding. Patient front view (A), intraoral pictures (B), and study models (C).

79

80 PA RT I I I    Palatal Implants

E

D

• Fig. 7.12 cont’d

TABLE   Case 2, Cephalometric Summary 7.2 

Pretreatment

Posttreatment

NSBa

131.7 degrees

132.5 degrees

NL-NSL

11.1 degrees

11.7 degrees

ML-NSL

40.7 degrees

40.8 degrees

ML-NL

29.6 degrees

29.1 degrees

SNA

78.1 degrees

77.3 degrees

SNB

73.0 degrees

72.6 degrees

ANB

5.1 degrees

4.7 degrees

Wits

6.7 mm

3.9 mm

U1-NL

111.7 degrees

107.6 degrees

L1-ML

96.2 degrees

92.5 degrees

U1-L1

122.6 degrees

130.7 degrees

Overjet

4.7 mm

3.7 mm

Overbite

2.8 mm

2.6 mm

quadrant (Fig. 7.16). After 20 months, all the interdental spaces were closed to the distal, with the digitally planned positions of the maxillary teeth realized in the final anteriorposterior position. The Beneslider appliance was removed, since absolute molar anchorage was not required for the final finishing phase (Fig. 7.17) of treatment. Comprehensive treatment was completed after 22 months (Figs. 7.18 and 7.19), and the palatal mini-implants were removed without anesthesia. 

• Fig. 7.13  Beneslider in place with an additional tube at the upper first left bicuspid.

Clinical Considerations Our initial approach to combining sequential plastic aligner therapy and the Beneslider appliance involved a two-phase protocol: phase 1: distalization, and after distalization of the maxillary molar to proceed with phase 2: impression/scan and finishing with aligners.39 Advantages of this two-phase procedure: •  No need for coordination of tooth movement with Beneslider and aligners. • An expected requirement for fewer aligners to achieve treatment objectives. Disadvantages of the two-phase procedure: • An expected increased treatment time. To reduce the total treatment time, we modified our approach to a single-phase protocol involving

CHAPTER 7  Asymmetric Noncompliance Upper Molar Distalization in Aligner Treatment Using Palatal TADs and the Beneslider

81

A

C

B •

Fig. 7.14  After 7 months of distalization, several small interdental spaces were visible in between the upper left posterior dental segment. An elastic chain was added for retraction of the upper left first bicuspid. Upper jaw (A) and radiographs (B, C).

A •

Fig. 7.16 After 16 months of treatment. A steel ligature is used between the bonded tube and the activation lock to use the Beneslider as a passive molar anchorage device.

B • Fig. 7.15  Beneslider and aligner in place: the aligner material is cover-

ing the connection area on the palatal side of the molar. Upper jaw (A) and palatal view on the second quadrant (B).

simultaneous distalization and alignment with sequential plastic aligners. We have found that a single-phase protocol is associated with significantly reduced overall treatment time. The potential drawback with this approach is the coordination between the Beneslider appliance and planned aligner tooth movements. If the distalization force and/or the rate of distal molar movement are excessive compared to the aligner staging, the fit and accuracy of the aligner may be undermined with the appearance of maxillary interdental spacing. A second factor to be considered is the possibility of insufficient aligner wear by the patient. If this is recognized during active treatment,

82 PA RT I I I    Palatal Implants

• Fig. 7.17  After 20 months: all spaces are closed to the distal.

A

B • Fig. 7.18  After removal of the Beneslider in the final finishing phase. Upper jaw (A) and cephalogram (B).

the rate of distalization may be reduced or the wear time of an aligner may be prolonged, for example, wearing each aligner for two weeks instead of one. The rate of the maxillary molar distal movement associated with the use of a Beneslider appliance is approximately 0.6 mm per month42; this rate of molar distalization speed should be kept in mind when determining the appropriate aligner staging (ClinCheck). The distalization force can be directly applied to the first or second molar teeth. To have a maximum retention with the teeth that are to be moved distally, we recommend bonding the Beneslider to the first molar teeth instead of the second molars. If the distalization forces are applied to the second molars and the aligner fitting at the second molars is

not perfect, small unexpected spaces can develop in between the upper first and second molar teeth (see Fig. 7.16). In this situation, the distalization force must be reduced to regain aligner fitting. Another point that must be recognized: when a refinement is planned and new aligners are ordered, the Beneslider must be maintained in a passive manner to ensure the accuracy of the fit of the aligner. The anterior hard palate has proven to be the most convenient region of the maxilla for insertion of miniimplants.27,28 Since there are no roots, blood vessels, or nerves, the risk of a complication associated with the placement of a mini-implant is minimal. Even the penetration of the nasal cavity does not result in any problems.

CHAPTER 7  Asymmetric Noncompliance Upper Molar Distalization in Aligner Treatment Using Palatal TADs and the Beneslider

83

A

B

C

E

D • Fig. 7.19  Treatment

result after 22 months (A, C, D, E) with a three-dimensional scan of before and

after (B, left side).

Recently, a computer-aided design/computer-aided manufacturing (CAD/CAM) manufactured insertion guide was introduced (Easy Driver, Parma, Italy), which facilitates safe and precise insertion of mini-implants in the anterior hard palate, allowing the opportunity for the use of palatal implants to the less experienced clinician. Secondly, these insertions guides allow for the insertion of mini-implants and installation of the appliance in a single office visit.43 

Conclusions • By using palatal mini-implants and a Beneslider device, unilateral or bilateral distal tooth movement can be realized without anchorage loss. • The Beneslider can be easily integrated in aligner therapy by using bonded tubes on the palatal surfaces. • A combined, single-phase treatment approach with simul­ taneous distalization and alignment is possible.

84 PA RT I I I    Palatal Implants

References 1. Clemmer EJ, Hayes EW: Patient cooperation in wearing orthodontic headgear, Am J Ortho 75:517–524, 1979. 2. Egolf RJ, BeGole EA, Upshaw HS: Factors associated with orthodontic patient compliance with intraoral elastic and headgear wear, Am J Orthod Dentofacial Orthop 97:336–348, 1990. 3. Fortini A, Lupoli M, Giuntoli F, Franchi L: Dentoskeletal effects induced by rapid molar distalization with the first class appliance, Am J Orthod Dentofacial Orthop 125:697–704, 2004; discussion 704-705. 4. Bussick TJ, McNamara Jr JA: Dentoalveolar and skeletal changes associated with the pendulum appliance, Am J Orthod Dentofacial Orthop 117:333–343, 2000. 5. Ghosh J, Nanda RS: Evaluation of an intraoral maxillary molar distalization technique, Am J Orthod Dentofacial Orthop 110:639–646, 1996. 6. Byloff FK, Karcher H, Clar E, Stoff F: An implant to eliminate anchorage loss during molar distalization: a case report involving the Graz implant-supported pendulum, Int J Adult Orthodon Orthognath Surg 15:129–137, 2000. 7. Gelgör IE, Buyukyilmaz T, Karaman AI, Dolanmaz D, Kalayci A: Intraosseous screw-supported upper molar distalization, Angle Orthod 74:838–850, 2004. 8. Karaman AI, Basciftci FA, Polat O: Unilateral distal molar movement with an implant-supported distal jet appliance, Angle Orthod 72:167–174, 2002. 9. Kyung SH, Hong SG, Park YC: Distalization of maxillary molars with a midpalatal miniscrew, J Clin Orthod 37:22–26, 2003. 10. Sugawara J, Kanzaki R, Takahashi I, Nagasaka H, Nanda R: Distal movement of maxillary molars in nongrowing patients with the skeletal anchorage system, Am J Orthod Dentofacial Orthop 129:723–733, 2006. 11. Kircelli BH, Pektas ZO, Kircelli C: Maxillary molar distalization with a bone-anchored pendulum appliance, Angle Orthod 76:650–659, 2006. 12. Escobar SA, Tellez PA, Moncada CA, Villegas CA, Latorre CM, Oberti G: Distalization of maxillary molars with the bonesupported pendulum: a clinical study, Am J Orthod Dentofacial Orthop 131:545–549, 2007. 13. Kinzinger G, Gulden N, Yildizhan F, Hermanns-Sachweh B, Diedrich P: Anchorage efficacy of palatally-inserted miniscrews in molar distalization with a periodontally/miniscrew-anchored distal jet, J Orofac Orthop 69:110–120, 2008. 14. Velo S, Rotunno E, Cozzani M: The implant distal jet, J Clin Orthod 41:88–93, 2007. 15. Kinzinger GS, Diedrich PR, Bowman SJ: Upper molar distalization with a miniscrew-supported Distal Jet, J Clin Orthod 40:672–678, 2006. 16. Costa A, Raffainl M, Melsen B: Miniscrews as orthodontic anchorage: a preliminary report, Int J Adult Orthodon Orthognath Surg 13:201–209, 1998. 17. Freudenthaler JW, Haas R, Bantleon HP: Bicortical titanium screws for critical orthodontic anchorage in the mandible: a preliminary report on clinical applications, Clin Oral Implants Res 12:358–363, 2001. 18. Kanomi R: Mini-implant for orthodontic anchorage, J Clin Orthod 31:763–767, 1997. 19. Melsen B, Costa A: Immediate loading of implants used for orthodontic anchorage, Clin Orthod Res 3:23–28, 2000.

20. Wilmes B: Fields of application of mini-implants. In Ludwig B, Baumgaertel S, Bowman J, editors: Innovative anchorage concepts. Mini-implants in orthodontics, Berlin, New York, 2008, Quintessenz, 91–122. 21. Wilmes B, Olthoff G, Drescher D: Comparison of skeletal and conventional anchorage methods in conjunction with pre-operative decompensation of a skeletal class III malocclusion, J Orofac Orthop 70:297–305, 2009. 22. Wilmes B, Nienkemper M, Ludwig B, Kau CH, Drescher D: Early class III treatment with a hybrid hyrax-mentoplate combination, J Clin Orthod 45:1–7, 2011. 23. Ravera S, Castroflorio T, Garino F, Daher S, Cugliari G, Deregibus A: Maxillary molar distalization with aligners in adult patients: a multicenter retrospective study, Prog Orthod 17:12, 2016. 24. Bowman SJ, Celenza F, Sparaga J, Papadopoulos MA, Ojima K, Lin JC: Creative adjuncts for clear aligners, part 1: class II treatment, J Clin Orthod 49:83–94, 2015. 25. Simon M, Keilig L, Schwarze J, Jung BA, Bourauel C: Treatment outcome and efficacy of an aligner technique—regarding incisor torque, premolar derotation and molar distalization, BMC Oral Health 14:68, 2014. 26. Lim HJ, Choi YJ, Evans CA, Hwang HS: Predictors of initial stability of orthodontic miniscrew implants, Eur J Orthod 33:528– 532, 2011. 27. Hourfar J, Bister D, Kanavakis G, Lisson JA, Ludwig B: Influence of interradicular and palatal placement of orthodontic miniimplants on the success (survival) rate, Head Face Med 13:14, 2017. 28. Wilmes B, Ludwig B, Vasudavan S, Nienkemper M, Drescher D: The T-zone: median vs. paramedian insertion of palatal miniimplants, J Clin Orthod 50:543–551, 2016. 29. Ludwig B, Glasl B, Bowman SJ, Wilmes B, Kinzinger GS, Lisson JA: Anatomical guidelines for miniscrew insertion: palatal sites, J Clin Orthod 45:433–441, 2011. 30. Nienkemper M, Pauls A, Ludwig B, Drescher D: Stability of paramedian inserted palatal mini-implants at the initial healing period: a controlled clinical study, Clin Oral Implants Res 26:870– 875, 2015. 31. Wilmes B, Drescher D: A miniscrew system with interchangeable abutments, J Clin Orthod 42:574–580, 2008; quiz 595. 32. Wilmes B, Drescher D, Nienkemper M: A miniplate system for improved stability of skeletal anchorage, J Clin Orthod 43:494– 501, 2009. 33. Wilmes B, Drescher D: Application and effectiveness of the Beneslider molar distalization device, World J Orthod 11:331–340, 2010. 34. Wilmes B, Rademacher C, Olthoff G, Drescher D: Parameters affecting primary stability of orthodontic mini-implants, J Orofac Orthop 67:162–174, 2006. 35. Wilmes B, Ottenstreuer S, Su YY, Drescher D: Impact of implant design on primary stability of orthodontic mini-implants, J Orofac Orthop 69:42–50, 2008. 36. Wilmes B, Su YY, Sadigh L, Drescher D: Pre-drilling force and insertion torques during orthodontic mini-implant insertion in relation to root contact, J Orofac Orthop 69:51–58, 2008. 37. Wilmes B, Su YY, Drescher D: Insertion angle impact on primary stability of orthodontic mini-implants, Angle Orthod 78:1065– 1070, 2008. 38. Wilmes B, Nienkemper M, Drescher D: Application and effectiveness of a new mini-implant and tooth-borne rapid palatal expansion device, The Hybridhyrax World J Orthod 323–330, 2010.

CHAPTER 7  Asymmetric Noncompliance Upper Molar Distalization in Aligner Treatment Using Palatal TADs and the Beneslider

39. Wilmes B, Nienkemper M, Ludwig B, Kau CH, Pauls A, Drescher D: Esthetic class II treatment with the Beneslider and aligners, J Clin Orthod 46:390–398, 2012. 40. Wilmes B, Neuschulz J, Safar M, Braumann B, Drescher D: Protocols for combining the Beneslider with lingual appliances in Class II treatment, J Clin Orthod 48:744–752, 2014. 41. Wilmes B, Katyal V, Willmann J, Stocker B, Drescher D: Miniimplant-anchored Mesialslider for simultaneous mesialisation and intrusion of upper molars in an anterior open bite case: a three-year follow-up, Aust Orthod J 31:87–97, 2015.

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42. Nienkemper M, Wilmes B, Pauls A, Yamaguchi S, Ludwig B, Drescher D: Treatment efficiency of mini-implant-borne distalization depending on age and second-molar eruption, J Orofac Orthop 75:118–132, 2014. 43. De Gabriele O, Dallatana G, Riva R, Vasudavan S, Wilmes B: The easy driver for placement of palatal mini-implants and a maxillary expander in a single appointment, J Clin Orthod 51: 728–737, 2017.

     

PART IV

Skeletal Plates

8. Nonextraction Treatment of Bimaxillary Anterior Crowding With Bioefficient Skeletal Anchorage Junji Sugawara, Satoshi Yamada, So Yokota and Hiroshi Nagasaka 9. Managing Complex Orthodontic Problems With Skeletal Anchorage Mithran Goonewardene, Brent Allan and Bradley Shepherd

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8

Nonextraction Treatment of Bimaxillary Anterior Crowding With Bioefficient Skeletal Anchorage JUNJI SUGAWARA, SATOSHI YAMADA, SO YOKOTA, HIROSHI NAGASAKA

T

his chapter describes the treatment of two patients in which significant distalization of the buccal segments, using miniplates to relieve anterior crowding, was accomplished in the maxilla and mandible.

Case 1

to the space analysis with wax setup models and cone-beam computed tomography (CBCT) evaluation, both treatment options were feasible in this case. Since the patient was reluctant to have four premolars extracted, she chose a nonextraction approach with the application of skeletal anchorage. 

Chief Complaint

Case 2

A 23-year-old female patient’s chief complaint was that her upper and lower anterior teeth showed crowding and partial anterior crossbite. The patient had no history of previous orthodontic treatment. Medical history was noncontributory, and findings from the temporomandibular joint (TMJ) examination were normal with adequate range of movements. 

Chief Complaint

Diagnosis and Case Summary (Tables 8.1–8.4; Figs. 8.1 and 8.2) She presented with a slightly concave profile because of a large mandible and a mild maxillary deficiency (Wits appraisal: −6.0 mm). She had a Class III denture base with partial anterior crossbite and anterior crowding in the upper and lower dentition. Mandibular dental midline was shifted to the left by 1 mm because of mandibular asymmetry. 

Treatment Options (Tables 8.5 and 8.6; Figs. 8.3–8.14) Two alternatives were considered as treatment options for the correction of maxillary and mandibular crowding and partial anterior crossbite. The first option was four premolar extractions and the other one was a nonextraction treatment consisting of distalization of the maxillary and mandibular posterior teeth after extraction of all third molars. According

A 31-year-old female patient’s chief complaint was that her upper and lower anterior teeth showed crowding, TABLE   Extraoral Analysis 8.1  Facial form

Mesoprosopic

Facial asymmetry

Slight mandibular shift to the left side

Chin point

Slightly shifted to left side

Occlusal plane

Normal

Facial profile

Slightly concave because of a prognathic mandible

Facial height

Upper facial height/lower facial height: normal Lower facial height/throat depth: normal

Lips

Competent, upper: normal, lower: protrusive

Nasolabial angle

Normal

Mentolabial sulcus

Normal

Malar prominence

Normal

89

90 PA RT I V    Skeletal Plates

TABLE   Intraoral Analysis and Functional Analysis 8.3 

TABLE   Smile Analysis 8.2  Smile arc

Consonant

Incisor display

Rest: 0 mm

Intraoral analysis

Teeth present

87654321/12345678 87654321/12345678

Smile: 9 mm (no gingival display) Lateral tooth display

Maxillary molar to molar

Molar relation

Class III bilaterally

Buccal corridor

Narrow

Canine relation

Class III bilaterally

Gingival tissue

Gingival margins: even height of maxillary incisors

Overjet

0 mm

Overbite

0 mm

Papilla

Present in all teeth

Maxillary arch

Dentition

No gingivitis and periodontitis

U shaped, anterior crossbite (except central incisors) and 10 mm of crowding

Mandibular arch

U shaped and 10 mm of crowding

Oral hygiene

Fair

Tooth size and proportion: normal Tooth shape: normal No tooth wear Incisal embrasure

Normal

Midlines

Lower midline shifted to the left side by 1 mm as compared with the facial midline

Occlusal plane

Normal

Functional analysis

Swallowing

Normal adult pattern

Temporomandibular joint

Normal with adequate range of jaw movements

TABLE   Problem List 8.4  Pathology/others

Significant short roots of the maxillary central incisors Significant mesial angulation of the mandibular left third molar

Alignment

6 mm of crowding in maxillary arch and 8 mm of crowding in the mandibular arch

Dimension

Skeletal

Dental

Soft Tissue

Anteroposterior

Mild Skeletal Class III

Overjet = 0 mm

Protrusive lower lip

Class III canine and molar relation bilaterally

Slightly prognathic profile

Vertical

Low mandibular plane angle

Overbite = 0 mm Edge to edge bite

Transverse

Mandible is slightly shifted to the left

Lower dental midline is shifted to the left by 1 mm, as compared with the facial midline

Mandible is slightly shifted to the left

CHAPTER 8  Nonextraction Treatment of Bimaxillary Anterior Crowding With Bioefficient Skeletal Anchorage

• Fig. 8.1  Pretreatment extraoral/intraoral photographs and panoramic radiograph.

A

B

• Fig. 8.2  (A) Pretreatment lateral cephalogram. (B) Template cephalometric analysis (Black, patient; red, Japanese norm).

91

92 PA RT I V    Skeletal Plates

TABLE   Treatment Objectives 8.5  Pathology/others

Monitor short roots of maxillary central incisors Extract all third molars

Alignment

Distalize maxillary and mandibular posterior teeth

Dimension

Skeletal

Dental

Tissue

Anteroposterior

Maintain mild Skeletal Class III

Distalize maxillary and mandibular posterior teeth, and improve anterior crowding and Class III denture base

Slightly improve on the lower lip eversion

Retrocline mandibular incisors Vertical

Maintain present mandibular plane angle

Transverse

Retrocline maxillary and mandibular incisors Maintain present transverse relation between maxillary and mandibular dentition

Maintain present mandibular position

TABLE   Treatment Sequence and Biomechanical Plan 8.6 

Maxilla

Mandible

Extracted maxillary third molars bilaterally

Extracted mandibular third molars bilaterally

Bonded posterior teeth, inserted passive segmental 0.016 × 0.022 -inch CNA archwires.

Bonded posterior teeth, inserted passive segmental 0.016 × 0.022 -inch CNA archwires were placed.

Placed SAS bone plates bilaterally at the zygomatic buttresses next to the first molars. Delivered 200 g of distalization force on each posterior tooth with elastometric chains.

Placed SAS bone plates bilaterally at the mandibular body next to the first molars. Delivered 200 g of distalization and intrusion force on each posterior tooth with elastometric chains.

Placed 0.016 × 0.022 -inch CNA archwires and changed to 0.017 × 0.025 -inch CNA wire segments after leveling of posterior teeth was complete.

Placed 0.016 × 0.022 -inch CNA archwires and changed to 0.017 × 0.025 -inch CNA wires segments after leveling of posterior teeth was complete

Bonded anterior teeth and started overall alignment with 0.014, 0.016, 0.016 × 0.016, 0.016 × 0.022, 0.017 × 0.025 -inch NiTi archwires. Continued distalization force.

Bonded anterior teeth and started overall alignment with 0.014, 0.016, 0.016 × 0.016, 0.016 × 0.022, 0.017 × 0.025 -inch NiTi archwires. Continue distalization force.

After making space between lateral incisors and canines, 0.016 × 0.022 -inch SS retraction arch with L-loop was engaged. 0.016 × 0.022, 0.017 × 0.025 -inch SS archwires were placed for finishing and detailing.

0.016 × 0.022, 0.017 × 0.025 -inch SS archwires were placed for finishing and detailing.

Debond and lingual bonded retainers.

Debond and lingual bonded retainers

6-month recall appointment for retention check.

6-month recall appointment for retention check

CNA, Connecticut new archwire; NiTi, nickel titanium; SAS, skeletal anchorage system; SS, stainless steel

CHAPTER 8  Nonextraction Treatment of Bimaxillary Anterior Crowding With Bioefficient Skeletal Anchorage

A

B • Fig. 8.3  (A) Visualized treatment goal (Blue, pretreatment; red, goal). (B) Wax setup model.

A

B • Fig. 8.4  (A) Cone-beam computed tomography (CBCT) of right side posterior teeth (see root apex of #47). (B) CBCT of left side posterior teeth (see root apex of #37).

93

94 PA RT I V    Skeletal Plates

A

B

C • Fig. 8.5  (A and B) Biomechanics for distalization of bimaxillary posterior teeth. (C) Panoramic radiograph after implantation of orthodontic miniplates.

• Fig. 8.6  Simultaneous distalization of maxillary and mandibular posterior teeth using Skeletal Anchorage System and segmental archwires with power hooks (2.6 months later).

• Fig. 8.7  Bonding brackets on maxillary anterior teeth except for #22. Distalization of bimaxillary posterior teeth continued (4.2 months later).

• Fig. 8.8  Bonding brackets on the remaining teeth. Distalization of bimaxillary posterior teeth continued (6.4 months later).

• Fig. 8.9  Alignment of the bimaxillary dentition and distalization of the maxillary right posterior teeth (8.4 months later).

96 PA RT I V    Skeletal Plates

•

Fig. 8.10 Aligning of the bimaxillary dentition and distalization of maxillary right posterior teeth (10.5 months later).

• Fig. 8.11  Detailing and finishing (13.7 months later).

CHAPTER 8  Nonextraction Treatment of Bimaxillary Anterior Crowding With Bioefficient Skeletal Anchorage

• Fig. 8.12  Posttreatment extraoral/intraoral photographs and panoramic radiograph.

A

B

C

• Fig. 8.13  (A) Lateral cephalometric radiograph at debonding. (B) Cephalometric superimposition before and after. (C) Occlusogram superimposition before and after. Blue, Pretreatment; red, posttreatment.

97

98 PA RT I V    Skeletal Plates

A

B • Fig. 8.14  (A) Cone-beam computed tomography (CBCT) of right hand side posterior teeth (see root apex of #47). (B) CBCT of left hand side posterior teeth (see root apex of #37).

TABLE   Extraoral Analysis 8.7 

TABLE   Smile Analysis 8.8 

Smile Analysis

Facial form

Mesoprosopic

Facial asymmetry

Normal

Chin point

Normal

Occlusal plane

Normal

Facial profile

Straight

Lateral tooth display

Maxillary first molar to first molar

Facial height

Upper facial height/lower facial height: long lower facial height

Buccal corridor

Narrow

Gingival tissue

Margins: right maxillary canine margin is high

Lower facial height/throat depth: normal Lips

Competent, upper: protrusive, lower: protrusive

Nasolabial angle

Acute

Mentolabial sulcus

Shallow

Malar prominence

Normal

particularly a high canine of the right side. The patient had no history of previous orthodontic treatment. Medical history was noncontributory, and findings from the TMJ examination were normal with adequate range of movements. 

Diagnosis and Case Summary (Tables 8.7– 8.10; Figs. 8.15 and 8.16) Her skeletal profile was classified into skeletal Class I with long face. She presented with a bimaxillary dento-alveolar

Smile arc

Consonant

Incisor display

Rest: 3.5 mm Smile: 12 mm (100% with 3 mm of gingival display)

Papilla: present Gingivitis and periodontitis at bimaxillary posterior teeth (Deep pocket depth between the maxillary second and third molars) Dentition

Tooth size and proportion: normal Tooth shape: normal No tooth wear

Incisal embrasure

Normal

Midlines

Upper and lower midline shifted to the right side by 2.5 mm and 1 mm, respectively

CHAPTER 8  Nonextraction Treatment of Bimaxillary Anterior Crowding With Bioefficient Skeletal Anchorage

99

TABLE   Intraoral Analysis and Functional Analysis 8.9  Intraoral Analysis

Teeth present

87654321/12345678 87654321/12345678

Molar relation

Class III bilaterally

Canine relation

Class III bilaterally

Overjet

2 mm

Overbite

2 mm

Maxillary arch

U shaped and 7.7 mm of crowding

Mandibular arch

U shaped and 7.1 mm of crowding

Oral hygiene

Poor Functional Analysis

Swallowing

Normal adult pattern

Temporomandibular Joint

Normal and adequate range of jaw movement

TABLE   Problem List 8.10  Pathology/­others

Significant vertical alveolar bone loss between the maxillary second and third molars bilaterally

Alignment

7.7 mm of crowding present in maxillary arch 7.1 mm of crowding in mandibular arch

Dimension

Skeletal

Anteroposterior

Dental

Soft Tissue

Crossbite on right lateral incisor

Protrusive upper and lower lips

Class III canine and molar relation Vertical

Overbite = 2 mm

Transverse

Upper and lower dental midline is shifted to the right by 2.5 mm and 1 mm respectively as compared with the facial midline

protrusion profile because of large maxilla and mandible, and proclination of upper and lower incisors. She had a mild Class III denture and anterior crowding in the upper and lower dentition. Both maxillary and mandibular dental midline shifted to the right by 2.5 mm and 1.0 mm, respectively. 

Treatment Options (Tables 8.11 and 8.12; Figs. 8.17–8.28) Her treatment options were quite similar to Case 1. We proposed two options for the correction of her orthodontic problems, particularly for the correction of bimaxillary

anterior crowding. The first option consisted of four premolar extraction, and the other one was nonextraction treatment by distalization of maxillary and mandibular posterior teeth after extraction of maxillary second molars and mandibular third molars. Since vertical alveolar bone loss was observed between maxillary second and third molars, bone regeneration was expected following distal movement of the maxillary first molars and mesial movement of the maxillary third molars. According to the space analysis observed in the wax setup models and CBCT evaluation, both treatment options were feasible in this case. After considering risks and benefits of these two options, the patient chose nonpremolar extraction treatment.

100 PA RT I V    Skeletal Plates

• Fig. 8.15  Pretreatment extraoral/intraoral photographs and panoramic radiograph.

A

B

• Fig. 8.16  (A) Pretreatment lateral cephalogram. (B) Template cephalometric analysis (Black, patient; red, Japanese norm).

CHAPTER 8  Nonextraction Treatment of Bimaxillary Anterior Crowding With Bioefficient Skeletal Anchorage

TABLE   Treatment Objectives 8.11  Pathology/others

Extract upper second molars and lower third molars Expect bone regeneration of upper second molar region

Alignment

Distalize maxillary and mandibular posterior teeth, and mesialize maxillary third molars

Dimension

Skeletal

Dental

Soft Tissue

Anteroposterior

Maintain

Distalize maxillary and mandibular posterior teeth and improve Class III canine and molar relation, and anterior crowding Retrocline mandibular incisors Correct anterior crossbite on maxillary right lateral incisor

Reduce lip protrusion

Vertical

Maintain

Maintain overbite and present maxillary incisor display

Maintain

Transverse

Maintain

Match midlines

TABLE   Treatment Sequence and Biomechanical Plan 8.12 

Maxilla

Mandible

Extracted maxillary second molars bilaterally

Extracted mandibular third molars bilaterally

Bonded posterior teeth, passive segmental 0.016 × 0.022 -inch CNA archwires.

Bond posterior teeth, passive segmental with 0.016 × 0.022 -inch CNA archwires were placed.

Placed SAS bone plates bilaterally at the zygomatic buttresses next to the first molars. Delivered 200 g of distalization force on each posterior tooth with elastometric chains.

Placed SAS bone plates bilaterally at the mandibular body next to the first molars. Deliver 200 g of distalization force on each posterior tooth with elastometric chains.

Placed 0.016 × 0.022 -inch CNA wires segments and changed to 0.017 × 0.025 inch CNA archwire segments after leveling of posterior teeth was complete. Retracted canines with segmental T-loop wires.

Placed 0.016 × 0.022 -inch CNA wires segments and changed to 0.017 × 0.025 -inch CNA archwire segments after leveling of posterior teeth was complete.

Bonded anterior teeth (except for right lateral incisor) and started alignment with 0.014, 0.016, 0.016 × 0.016, 0.016 × 0.022, 0.017 × 0.025 -inch NiTi archwires. Continued distalization force. After making space for right lateral incisor, bonded and aligned entire dentition.

Bonded anterior teeth and started overall alignment with 0.014, 0.016, 0.016 × 0.016, 0.016 × 0.022, 0.017 × 0.025 -inch NiTi archwires. Started to distalize entire dentition with elastometric chains.

After making space between lateral incisors and canines, 0.017 × 0.025 -inch CNA contraction arch with Bull-loop was engaged. 0.016 × 0.022, 0.017 × 0.025 -inch SS archwires were placed for finishing and detailing.

.016 × 0.022, 0.017 × 0.025 -inch SS archwires were placed for finishing and detailing.

Debonded and placed lingual bonded retainers.

Debonded and placed lingual bonded retainers

6-month recall appointment for retention check.

6-month recall appointment for retention check

CNA, Connecticut new archwire; NiTi, nickel titanium; SAS, skeletal anchorage system; SS, stainless steel

101

102 PA RT I V    Skeletal Plates

A

B • Fig. 8.17  (A) Visualized treatment goal (Blue, pretreatment; red, goal). (B) Wax setup model.

A

B

• Fig. 8.18  (A) Cone-beam computed tomography (CBCT) of right hand side posterior teeth (see root apex of #47). (B) CBCT of left hand side posterior teeth (see root apex of #37).

CHAPTER 8  Nonextraction Treatment of Bimaxillary Anterior Crowding With Bioefficient Skeletal Anchorage

A

B

C • Fig. 8.19  (A and B) Biomechanics for distalization of bimaxillary posterior teeth. (C) Panoramic radiograph after implantation of orthodontic miniplates.

• Fig. 8.20  Simultaneous distalization of maxillary and mandibular posterior teeth using Skeletal Anchorage System and segmental archwires with power hooks (2.0 months later).

103

104 PA RT I V    Skeletal Plates

• Fig. 8.21  Maxillary canine retraction and simultaneous distalization of maxillary and mandibular posterior teeth using Skeletal Anchorage System and segmental archwires. Bonding brackets on mandibular anterior teeth (2.8 months later).

• Fig. 8.22  Bonding brackets on maxillary anterior teeth. Distalization of maxillary left and mandibular posterior teeth continued. Labial movement of #12 began (4.6 months later).

CHAPTER 8  Nonextraction Treatment of Bimaxillary Anterior Crowding With Bioefficient Skeletal Anchorage

•

Fig. 8.23  Distalization of maxillary right posterior teeth and mandibular entire dentition continued (6.7 months later).

• Fig. 8.24  Distalization of mandibular entire dentition continued (9.1 months later).

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• Fig. 8.25  Contraction of maxillary incisors using Bull loops. Tying back of all canines (12.3 months later).

• Fig. 8.26  Posttreatment extraoral/intraoral photographs and panoramic radiograph.

CHAPTER 8  Nonextraction Treatment of Bimaxillary Anterior Crowding With Bioefficient Skeletal Anchorage

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• Fig. 8.27  (A) Lateral cephalometric radiograph at debonding. (B) Cephalometric superimposition before and after. (C) Occlusogram superimposition before and after. Blue, Pretreatment; red, posttreatment.

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B • Fig. 8.28  (A) Cone-beam computed tomography (CBCT) of right hand side posterior teeth (see root apex of #47). (B) CBCT of left hand side posterior teeth (see root apex of #37).

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9

Managing Complex Orthodontic Problems With Skeletal Anchorage MITHRAN GOONEWARDENE, BRENT ALLAN, BRADLEY SHEPHERD

Introduction Biomechanical principles are the foundation for all orthodontic treatment. In particular, comprehension of Newton’s laws is essential in understanding force systems and the principles of “equilibrium,” effecting efficient biomechanical strategies and minimizing side effects from these force systems. Burstone described anchorage requirements as Group A (maximum), Group B (moderate), and Group C (minimum) (Fig. 9.1).1–3 Although Group B anchorage requirements are usually less challenging to achieve with most contemporary approaches, orthodontists are routinely challenged by treatment goals that may require Group A and Group C anchorage considerations. Patient cooperation with adjuncts such as elastics, extraoral traction, or removable appliances are often required. Moreover, specific types and magnitudes of tooth movement may be extremely difficult or impossible to achieve, such as complex intrusion, whole arch retraction, and molar protraction. The application of temporary anchorage devices (TADs) has progressively become a routine adjunct for challenging cases in most contemporary clinical practices since initially being introduced in the 1980s for direct or indirect anchors.4–8 Clinicians may now elect to manage most Group A and C anchorage cases with adjunctive application of TADs rather than the uncertainty and stress associated with adjuncts dependent on patient compliance.9 TADs have also expanded the envelope of predictable tooth movements that may be performed to compensate the dentition to camouflage skeletal discrepancies, reducing the need for orthognathic surgery. Moreover, complex tooth movements may now be considered in three dimensions including anchorage preservation during space closure,10 protraction/ retraction,11–13 intrusion/extrusion,14,15 and to assist in dento-facial orthopedics.16,17 Success rates in TAD devices ranged from 37% to 94%,15,18,19 and it is difficult to make valid comparisons.20,21 Complications have been reported, including screw loosening, fracture,22,23 infection, and damage to adjacent structures.22 Intimate screw-root proximity has been reported to reduce success by as much as one-third.22–24 Screw placement

in the alveolar bone is complicated by uncertainty with bone quality to guarantee successful placement.25 Miniplates have been suggested by Sugawara and Nishimura to overcome some of the limitations associated with alveolar placement of mini-implants.25,26 These may be fixed to cortical bone by several self-threaded titanium screws in areas of more predictable bone quality, such as the zygomatic buttress, retromolar pad, and along the mandibular body (Fig. 9.2). The arm of the bone plate exits transmucosally and may range from 10.5 mm (short) to 16.5 mm (long). The hook on the plate has a number of hooks to provide various level of force application dependent on the desired tooth movement. The body of the plate is positioned subperiosteally and is available in three different configurations (T, Y, or I). Although clinicians cite a lack of clinical guidelines and/ or skepticism of the evidence,27 and are concerned with the need for a more invasive surgical procedure, miniplates provide a more predictable and highly successful for a range of complex orthodontic movements.28–30 Bone plates may be preferred because their placement is more apical along the mandibular body or in the zygomatic buttress where bone quality is adequate and do not interfere with the path of most tooth movement. Bone plates may also be indicated difficult when root proximity limits the placement of mini-implants or when repeated failures may limit alternative locations.25 Moreover, greater forces may be applied in circumstances where whole arch retraction/ protraction may be required.31–33 It is important to note that even though studies report clinical success, there are often complications such as swelling, soft tissue hyperplasia, nerve damage, sinus perforation, or infection (15%).29 For screws, these complications often result in mobility and failure of the screw, but with miniplates, complications can usually be managed by excellent hygiene, topical application of antimicrobial agents, or antibiotics.31–34 It is important to appreciate that experience in treatment planning, placement, and managing any complication during treatment is necessary to ensure favorable outcomes of Skeletal Anchor System (SAS) plates. This chapter will demonstrate a number of selected applications of the SAS.  109

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1/3 2/3

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Maximum Anchorage (Group A)

Minimum Anchorage (Group C)

• Fig. 9.1  Maximum anchorage (Group A) mechanics describes tooth movements when posterior teeth

are anticipated to move anteriorly no more than one-third of the extraction space during space closure. Conversely minimum anchorage (Group C) facilitates at least two-thirds of the extraction space closure by posterior teeth moving forward.

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Fig. 9.2  Y-type (A) and L-type (B) miniplates placed in the zygomatic buttress and mandibular body. Miniplates exiting transmucosally high in the upper to facilitate significant intrusion and retraction (C) and in the lower (D).

Case 1: Reversing the Effects of Failed Growth Modification/Camouflage in a Skeletal Class II

adenoids appeared enlarged on the lateral cephalogram, but follow-up with an ear, nose, and throat specialist did not reveal any significant clinical indications for intervention (Fig. 9.3).

An 8-year-old male presented with his parents for treatment of a significant Class II division 1 type malocclusion in the early mixed dentition because of concerns with the possibility of incisor trauma from a large overjet.35 Facial evaluation revealed a significantly retrusive chin and incompetent lips. His

Problem List Increased overjet Significantly retrognathic mandible Upper spacing 

CHAPTER 9  Managing Complex Orthodontic Problems With Skeletal Anchorage

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Fig. 9.3  Facial (A–C) and intraoral (D–H) photos exhibit the significant Class II malocclusion and chin retrusion. Cephalometric radiograph with Mesh template overlay reveals a significant skeletal mandibular retrognathism and proclined upper incisors (I) and panoramic radiograph (J).

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Treatment Goals Reduce overjet by a combination of incisors retraction and increase in the horizontal projection of the mandible. 

Considerations The magnitude of the skeletal mandibular retrognathism is significant enough to discuss the possibility of surgery, as it is important to determine how the patient and parents will perceive success. Early treatment at this stage with a fixed or removable functional appliance may improve the dental relationships to some extent, but even with expression of the upper percentiles of jaw growth, the chin position will probably remain somewhat retrusive. The parents were also informed that early treatment is unlikely to provide significant benefit in the long term except for possible improvement in self-esteem at an earlier age. After careful consideration, the parents wished to proceed with a removable functional appliance. 

Treatment (Phase 1) A removable activator-type appliance with a headgear was selected by the patient and parents because of the suggestion that it may only need to be worn at home and to bed. The appliance was delivered and cooperation was excellent, with significant reduction of the overjet. After 9 months of treatment, the appliance was placed into a retention mode whereby night time wear was continued until all deciduous teeth had exfoliated. The acyclic on the appliance was modified as teeth exfoliated. 

Summary Although the dental relationships improved dramatically with reduction in overjet, the chin position remained significantly retrusive, and cephalometric analysis revealed a predominantly vertical response from the mandible and significantly protrusive lower incisors (Fig. 9.4). The functional appliance had effected significant proclining forces on the lower labial segment as has been reported.36 Moreover, this proclination has been reported to influence extraction decisions in the second stage of treatment with fixed appliances.36 Although the patient and parents were happy with the improvement, the patient lost interest in the appliance and ceased wearing it as a retainer. As a consequence, mild to moderate relapse of the dental relationships was observed (Fig. 9.5). Discussion now ensued, directed toward a surgical solution as the patient and parents now focused on his significant chin retrusion. However, a new problem of lower labial segment proclination now presented that would need to be addressed as part of presurgical decompensation.

Problem List (After Early Treatment) Severe mandibular retrognathism Class II type occlusal relationship Increased overjet and overbite Proclined lower incisors Bony chin deficiency   

 Considerations Simultaneous mandibular and genioplasty advancement surgery was planned, but the lower incisor proclination would have to be addressed before surgery. The conventional method to address this issue would be to remove two lower first premolars to provide space to retract and decompensate the anterior teeth. This would render the upper second molars nonfunctional after treatment, probably necessitating extraction. An option of placing two lower SAS plates at the time of third molar removal was discussed to act as anchors to retract the entire lower arch en masse and decompensate the teeth before simultaneous mandibular surgical advancement and advancement genioplasty. Consideration was also given to the option of placing all fixed appliances in place just before performing the jaw surgery, third molar removal, and placement of SAS plates. Lower arch retraction from an anterior crossbite relationship would be achieved after surgery. 

Treatment The unerupted third molars were removed primarily because of the surgeon’s concerns with simultaneous sagittal split surgery. T-configuration SAS plates were placed buccal to the lower first molars with three screws per side with third molar removal. The plates exited through the gingival tissues at or coronal to the mucogingival junction. When possible, it is important that the plate exits through attached keratinized tissue to minimize failure as with most types of temporary anchors.23 Lower fixed appliances were placed and elastomeric chain placed from the lower canines to the SAS plates to initiate the retraction force with a desire to effect greater tipping forces. Elastomeric chains were replaced every 2 to 3 weeks. Archwires progressed rapidly from 0.016 Niti through to 0.016 × 0.022 Niti and finally 0.019 × 0.025 β-Titanium alloys with a crimpable hook to direct the force closer to the center of resistance and effectively translate the entire lower arch. The progress photographs and lateral cephalograms demonstrate the uprighting of the lower anterior teeth from the SAS plates (Fig. 9.6). Upper fixed appliances were added toward the end of lower arch retraction to align and coordinate the arches following a similar archwire progression to the lower (i.e., 0.016 Niti through to 0.016 × 0.022 Niti and finally 0.019 × 0.025 β-Titanium alloy).

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• Fig. 9.4  Facial (A–C) and intraoral (D–H) photos exhibit improvement in the dental relationship but no

significant improvement in chin position. The cephalometric radiograph reveals significant proclination of the lower incisors (I).

Simultaneous mandibular advancement with a bilateral sagittal split osteotomy was performed with advancement genioplasty and removal of the bone plates (Fig. 9.7). The patient was guided into final occlusal relationships in 0.017 × 0.025 β-Titanium and seating elastics and the appliances removed and a combination of a fixed lower bonded retainer and a removable Hawley type retainer. 

Summary The dental relationships exhibited a most satisfactory occlusal outcome with an esthetic balanced facial form with normal facial convexity (Fig. 9.8.) 

Case 2: Decompensation of a Retreatment Case Presenting With Bimaxillary Dental Protrusion and Skeletal Class II Malocclusion A 24-year-old adult female presented with a primary concern of a perception of a protrusive set of teeth and a weak chin, following a previous course of orthodontic treatment involving fixed appliances and upper first premolar extractions. Facial evaluation revealed a symmetrical face with increased facial convexity characterized by a retrusive chin and protrusive lips. The intraoral views exhibited a Class I type relationship with minimal overjet and overbite, a

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I J • Fig. 9.5  Facial (A–C) and intraoral (D–H) photos exhibit slight relapse of the dental relationship and significant retrusion of the chin. The cephalometric radiograph reveals significant mandibular retrognathism with proclination of the lower incisors (I). Third molars are visible in the panoramic radiograph and provide bone volume to consider distal movement of the entire lower arch (J).

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• Fig. 9.6  Intraoral (A–C) photos exhibit fixed appliances, two miniplates lateral to the posterior teeth, and

elastomeric chain placed from extension arms to upright the lower anterior teeth. The cephalometric radiograph (D) and superimpositions (E) reveal significant uprighting of the lower incisors. The placement of the extension arm enables the fore system to lie closer to the center of resistance to facilitate translation of the lower arch with minimal rotation (F).

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• Fig. 9.7  Facial (A–C) and intraoral (D–F) photos exhibit excellent immediate postsurgical outcomes with improvement in chin position. The cephalometric radiograph (G) and superimpositions (H) reveal the outcome after simultaneous mandibular advancement and genioplasty.

therapeutic Class II molar relationship following extraction of the upper fist premolars and mild irregularity in the upper and lower aches (Fig. 9.9). The lateral cephalometric analysis reveals a significant Class II skeletal relationship characterized by significant mandibular retrognathism, a weak bony chin, proclined upper incisors, and severely proclined lower incisors (see Fig. 9.9).

Problem List Protrusive lips Retrusive chin Retrognathic mandible and bony chin deficiency Proclined upper and severely proclined lower incisors Minimal overbite and overjet

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• Fig. 9.8  Posttreatment facial (A–C) and intraoral (D–H) photos exhibit a balanced profile, excellent smile esthetics, and a good functional occlusion.

 Treatment Goals Reduction in lip and dental protrusion is the ultimate goal to satisfy the patient’s request. In addition, the relative and absolute chin projection must also be improved. 

Considerations Since the upper first premolars had already been extracted, reduction in upper dental protrusion could be achieved with the application of skeletal anchors or additional tooth extraction, such as the healthy first permanent molars. The lower dental protrusion requires Group A anchorage, and every mm of extraction space is required to maximally

retract the lower arch and decompensate the lower dentition. A simultaneous mandibular advancement and genioplasty could then be performed to idealize the chin and lip relationship. 

Treatment A plan was outlined to first remove the lower first premolars and all third molars and simultaneously place SAS bone plates lateral to the upper and lower first molars. Upper and lower fixed appliances were placed (Fig. 9.10). Upper and lower fixed appliances were placed and upper archwires progressed rapidly from 0.016 Niti through to 0.016 × 0.022 Niti and finally 0.019 × 0.025 β-Titanium

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I • Fig. 9.9  Facial (A–C) and intraoral (D–H) photos exhibit a Class I malocclusion with significant bimaxillary protrusion and a Class II molar relationship from previous upper arch extraction orthodontics, significant lip protrusion, and chin retrusion. Cephalometric radiograph with Mesh template overlay reveals a significant skeletal mandibular retrognathism, bony chin deficiency, and proclined upper and lower incisors (I) and panoramic radiograph (J).

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F • Fig. 9.10  Intraoral photos (A and B) exhibit fixed appliances, two miniplates lateral to the upper and lower posterior teeth and elastomeric chain placed from extension arms on a lower anterior segment to upright the lower anterior teeth. (C) Elastomeric chain was placed directly to the upper arch to facilitate whole arch retraction. The placement of the extension arm enables the force system to lie just above the center of resistance to facilitate controlled tipping of the lower anterior segment (D). The cephalometric radiograph (E) and superimpositions (F) reveal significant uprighting of the lower incisors.

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alloys. Elastomeric chain was placed from the upper canines to the SAS plates to initiate the retraction force with a desire to effect greater tipping forces. In the lower ach, only the lower canine-to-canine brackets were bonded with initial 0.016 Niti through to 0.016 × 0.022 Niti and finally 0.019 × 0.025 stainless steel segment with an extension arm bent gingivally distal to the canine to enable the elastomeric chain from the SAS plate to lie in a position to effect controlled frictionless tipping of the anterior segment (see Fig. 9.10). Once space had been closed, continuous archwires of 0.018 Niti through to 0.016 × 0.022 Niti and finally 0.019 × 0.025 β-Titanium alloy were placed to coordinate with the upper. The lower retraction proceeded rapidly and the whole ach retraction in the upper somewhat slower. Elastomeric chains were replaced every 2 to 3 weeks. The patient wished to finalize a surgical date, but the upper incisor retraction was incomplete. The use of SAS plates enabled the surgery to be performed and the plates retained so that final retraction of the upper arch could be achieved following the surgery (Fig. 9.11). Simultaneous mandibular advancement with a bilateral sagittal split osteotomy was performed with advancement genioplasty and removal of the lower bone plates only (Figs. 9.12 and 9.13). Following surgery, elastomeric chains were replaced every 2 to 3 weeks in the upper until ideal upper incisor position was achieved and the overjet idealized (Fig. 9.14). The patient was guided into final occlusal relationships in 0.017 × 0.025 β-Titanium and seating elastics and the appliances removed and a combination of a fixed upper and lower bonded retainers and a removable Hawley type retainers. 

Summary The final facial outcome was most impressive, with the patient thrilled with the overall changes in the dental inclinations, the lips flattening, and the chin projection. The patient exhibits an excellent occlusal outcome with sound intercuspation, well-aligned arches, and ideal overjet and overbite. The panoramic radiograph reveals acceptable root parallelism and minimal root resorption, and the lateral cephalogram and posttreatment tracing exhibit significant retraction of both upper and lower teeth on the respective skeletal bases and a well-balanced skeletal base relationship (Fig. 9.15). 

Case 3: A Complex Interdisciplinary Challenge Compromised by Previous Restorative Treatment A 37-year-old adult female presented with a complex dental history including childhood trauma to the upper anterior teeth resulting in devitalization, and ankyloses of the upper central incisor teeth failed in early adulthood and were replaced with implant-supported prostheses in their relatively submerged positions. The patient’s primary concerns

related to the esthetics of the smile with the reverse smile arc, reduce tooth display at rest and when smiling, and a convex profile with a retrusive chin. A number of posterior teeth had been heavily restored and the upper second and third molars have been lost (Fig. 9.16).

Problem List Reverse smile arc—upper central incisor implant prostheses in submerged positions Increased overjet Mandibular retrognathism Overerupted lower posterior teeth

 Treatment Goals Increase the vertical projection of the upper anterior teeth and improve the smile arc and increase the horizontal projection of the chin to address the chin deficiency and idealize the overjet. 

Considerations The patient had spent considerable funds on the implantsupported prostheses but did not want to proceed with replacement of the implants. It was carefully considered by the prosthodontist, and if the adjacent teeth could be extruded, the prosthetic component could be elongated and pink porcelain added to the gingival margin to improve the esthetics, as these did not have a high smile line. The only mechanism by which the overjet could be addressed would involve surgical mandibular advancement, but the overerupted second and third molars would interfere with mandibular advancement in their current positions. Skeletal anchors could be considered to intrude the lower posterior teeth before mandibular advancement. The lower third molars have no strategic role in this plan so they could be considered for extraction. 

Treatment An interdisciplinary plan was developed as outlined in Fig. 9.17 with an associated diagnostic set up. Full fixed appliances were placed with archwires progressing rapidly from 0.016 Niti through to 0.016 × 0.022 Niti and finally 0.017 × 0.025 and 0.019 × 0.025 β-Titanium alloys in the upper and lower arches, respectively. Elastomeric chains were placed vertically from the lower molars to the SAS plates to initiate the intrusion force (Figs. 9.18 and 9.19). Bonding of the upper brackets was carefully performed to facilitate extrusion of the upper lateral incisors and canines relative to the implanted upper central incisors (see Fig. 9.19). Additional adjustment bends to extrude the lateral incisors were incorporated into the upper archwire and compressed coils added to create space to facilitate increase in the mesiodistal dimensions of these teeth (Fig. 9.20).

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Fig. 9.11  Facial (A–C) and intraoral (D–H) photos exhibit fixed appliances with a Class II malocclusion following lower arch decompensation. The upper arch remained slightly proclined at this stage as seen in the radiograph (I). The panoramic radiograph reveals miniplates in the upper and lower extraction space closure (J).

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Fig. 9.12 Facial (A–C) and intraoral (D–F) photos exhibit excellent immediate postsurgical outcomes with improvement in chin position. The cephalometric radiograph (G) and superimpositions (H) reveal the outcome after simultaneous mandibular advancement and genioplasty. The upper teeth were still in a slightly protrusive position and the miniplates retained in the upper for ongoing postsurgical maxillary arch retraction.

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B • Fig. 9.13  The posttreatment cephalometric radiograph (A) and superimpositions (B) reveal the final out-

come after the upper incisor were retracted and the previous simultaneous mandibular advancement and genioplasty.

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• Fig. 9.14  The postsurgery intraoral photos (A–E) reveal the final outcome after the upper incisor were retracted.

Simultaneous mandibular advancement with a bilateral sagittal split osteotomy was performed with advancement genioplasty and removal of the lower bone plates (see Fig. 9.20). The patient was guided into final occlusal relationships in 0.017 × 0.025 β-Titanium, seating elastics and the appliances removed, and a combination of a fixed lower bonded retainer and removable Hawley type retainers (Fig. 9.21).

The upper central incisor crowns were placed with longer and wide teeth, and the upper lateral incisors restored with ceramic restorations. 

Summary The occlusal, esthetic, and functional goals were all achieved with an excellent occlusal relationship with ideal overjet and overbite. The heavily restored molars did not appear to suffer

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H • Fig. 9.15  Posttreatment facial (A–C) and intraoral (D–H) photos exhibit a balanced profile with pleasing changes in relative lip protrusion, excellent smile esthetics, and a good functional occlusion.

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J • Fig. 9.16  Facial (A–C) and intraoral (D–H) photos exhibit a Class II malocclusion with increased overjet, a

reverse smile arc, and two implant-supported prostheses placed in an inferior position and chin retrusion. Cephalometric radiograph with Mesh template overlay reveals a significant skeletal mandibular retrognathism (I), and the panoramic radiograph reveals overeruption of the unopposed lower second and third molars (J).

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any significant iatrogenic effects from the intrusive tooth movement. The facial profile was educed in convexity to a balanced position of the chin, but what really thrilled the patient was the restoration of normal consonant smile arc (Fig. 9.22).  Sequencing 1. Extraction of the lower third molars and placement of bone plates to facilitate intrusion of the second molars BA 2. Full fixed appliances (FFA) to align and coordinate the teeth within the arches upper lateral incisors will be extruded to increase the tooth display space opened to increase the mesiodistal size of the anterior teeth. The lower molars will intruded by elastomeric chains to the SAS plates MG 3. Mandibular orthognathic surgery (remove plates) BA 4. Post surgical detailing of the occlusion MG 5. Implant crowns elongated and widened BGS 6. Final Crowns BGS 7. Modification of retainer MG 8. Splint as retainer long term BGS

•

Fig. 9.17  The sequencing plan for the interdisciplinary treatment of the patient in Fig. 9.16 with the delegated clinicians. BA = Dr. Allan; MG = Dr. Goonewardene; BGS = Dr. Shepherd.

A

Case 4: A Complex Interdisciplinary Problem Characterized by Tooth Surface Loss, Dental Asymmetry, and Crowding A 36-year-old adult male presented with a primary complaint of poor dental esthetics, composite veneers that were placed to camouflage tooth irregularities, and tooth surface loss secondary to parafunction that is related to his highstress occupation. On examination, he presented with a symmetrical, slightly convex profile characterized by mild paranasal flattening and a mildly retrusive chin. Dentally, he exhibited a Class II subdivision right type malocclusion with an asymmetrical upper ach and normal overbite and overjet (Fig. 9.23). The right posterior teeth were more mesial than the left, the upper midline was deviated to the left, and both upper and low anterior teeth presented with moderate crowding and mild asymmetry with the posterior teeth on the left more anteriorly placed. There was significant tooth surface loss consistent with parafunction, and the Epworth Sleepiness score did not reflect a value indicative of a significant sleep disorder. The upper anterior teeth were irregular in alignment with significant discrepancies between the gingival margins that reflected compensatory eruption secondary to differential loss of vertical height. Skeletally, the lateral cephalogram exhibited a Class II skeletal pattern characterized by mild maxillary retrognathism and mandibular retrognathism and retroclined upper incisors.

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Fig. 9.18 Intraoral (A–E) photos exhibit fixed appliances, two miniplates lateral to the lower posterior teeth, and elastomeric chain to intrude the overerupted lower molars.

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Fig. 9.19 Facial (A–C) and intraoral (D–H) photos exhibit the presurgical relationships with spaces being prepared for restoration of the incisors. Note the purposeful extrusion of the upper lateral incisors. Cephalometric radiograph with superimposition reveals the significant intrusion of the lower posterior teeth (I and J).

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Fig. 9.20 Facial (A–C) and intraoral (D–H) photos exhibit excellent immediate postsurgical outcomes with improvement in chin position. The cephalometric radiograph (I) and superimpositions (J) reveal the outcome after simultaneous mandibular advancement and genioplasty.

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• Fig. 9.21  The intraoral photos at deband (A–E) reveal an excellent occlusal outcome before restoration of the incisor teeth. The crowns on the implants will be elongated and the spaces between the incisors will be used to increase the lateral incisor size.

Problem List Poor esthetics of compromised restorations Upper and lower crowding Tooth surface loss – Bruxism Asymmetrical upper arch and lower arches Mildly asymmetrical lower arch Class II subdivision right

 Treatment Goals Align the upper and lower teeth and address the upper midline discrepancy by moving teeth around to the right while simultaneously leveling the teeth vertically by selective intrusion to facilitate restoration of mesiodistal and inciso-gingival dimensions. The upper and lower left posterior teeth would be moved distally to simultaneously create space. The bruxing habit will need ongoing management with a splint and managing his personal stressors. A sequencing plan was developed to assist in the interdisciplinary communication between all parties (Fig. 9.24). 

Considerations The historical position for addressing a subdivisiontype malocclusion with an upper ach asymmetry would include consideration for extraction of the upper right first premolar. There is also a need for space in the lower arch. An alternative plan was presented that would include placement of skeletal anchors in three quadrants, the upper

right and both lower left and right quadrants. The skeletal anchors would be used to distal drive the right posterior teeth to create the necessary space for alignment/restoration and both lower. 

Treatment Full fixed appliances were placed with archwires progressing rapidly from 0.016 Niti through to 0.016 × 0.022 Niti, and finally 0.017 × 0.025 β-Titanium alloys in the upper and lower arches, respectively. SAS plates were inserted immediately lateral to the left and right upper first molars and the lower left first molars. No plate was required in the lower right quadrant soon after banding. Specific attention was directed toward accurate bracket placement on the anterior teeth to facilitate leveling of the gingival margins. Compressed coils were placed to open mesiodistal space and redistribute space indirectly created by distal driving from the SAS plates (Fig. 9.25). When acceptable mesiodistal spaces were created, brackets were removed and the teeth restored by the restorative dentist with composite resin to ideal form (Fig. 9.26). The restored teeth were rebracketed, and archwires progressed through to 0.019 × 0.025 β-Titanium alloys as the SAS plates were used to finalize the Class II posterior tooth correction. Following finishing procedures, the brackets were removed and the patient placed in fixed palatal and lingual retainers in the upper and lower arches and provisional clear thermoplastic retainers for full-time wear. After 6 months of retainer wear, final ceramic restorations were placed to idealize form and color of the anterior teeth and a splint provided to act as a retainer at night. 

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J I • Fig. 9.22  Posttreatment facial (A–C) and intraoral (D–H) photos exhibit a balanced profile, excellent smile

esthetics with pleasing changes in smile arc, and excellent functional occlusion. The cephalometric radiograph (I) reveals a balance skeletal and soft tissue outcome after simultaneous mandibular advancement and genioplasty. The panoramic radiograph reveals acceptable tooth positions with minimal root resorption of the posterior teeth that were intruded (J).

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J I • Fig. 9.23  Facial (A–C) and intraoral (D–H) photos exhibit a Class II subdivision right type malocclusion with upper and lower crowding and incisor

tooth wear. Compromise composite restorations have been placed to camouflage the irregular teeth. Note the upper and lower arch asymmetries (G and H). Cephalometric radiograph and analysis reveal mild skeletal mandibular retrognathism, retroclined upper incisors (I), bony chin deficiency, and proclined upper and lower incisors (I), and cone-beam computed tomography rendered panoramic radiograph reveals sound root morphology and third molars in situ (J).

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A Sequencing 1. Bone plates for anchorage

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2. Full fixed appliances

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a. Distal drive to create space b. Address asymmetry upper and lower 3. Provisional Build-Ups

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4. Complete Fixed appliances

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5. Final prosthodontics

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6. Splint as Retainer

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• Fig. 9.24  The sequencing plan for the interdisciplinary treatment of the patient in Fig. 9.23 with the del-

egated clinicians. (A) An occlusogram overlay of the treatment goals for the upper and lower reveals the need to distal drive the upper right and lower left quadrants to manage the asymmetry (B and C). BA = Dr. Allan; MG = Dr. Goonewardene; BGS = Dr. Shepherd.

Summary The upper and lower arch asymmetry was addressed by the asymmetrical forces systems delivered through the SAS plates. This corrected the Class II relationship and created space to restore the teeth to ideal mesiodistal form. In addition to these anteroposterior changes, selective intrusion of anterior teeth was performed to idealize the restorative dentistry (Fig. 9.27). Overall a most acceptable occlusal and esthetic outcome was achieved. 

Case 5: A Progressive Condylar Resorption Case That Developed Into a Class II Openbite A 10-year-old female presented for management of incipient crowding, as the upper right deciduous canine had been lost prematurely and the dental midline had deviated to the right. On examination, the patient presented with a symmetrical face and a slightly convex profile with a mildly retrusive chin. The characteristics of the smile were within the normal range. Intraoral examination revealed a Class II subdivision left malocclusion in the late mixed dentition with normal overbite and overjet, an upper arch asymmetry with the left posterior teeth more anteriorly placed, and upper midline deviation to the right. The skeletal characteristics reveal a mild Class II skeletal pattern characterized by mild

mandibular retrognathism and slightly retroclined upper incisors (Fig. 9.28). An initial stage of treatment was undertaken to move the upper posterior teeth distally with a pendulum appliance and create space for the anterior teeth. This progressed uneventfully over a 6-month period, and she was placed in a Nance holding device to hold the space. During the year that the Nance button was placed, the patient developed bilateral pain and clicking in both temporomandibular joints (TMJs). Antiinflammatory medication was prescribed, and an anterior openbite developed. The patient was referred to an oral medicine specialist and rheumatologist for routine diagnostic screening for any systemic contribution to the degenerative condition. The progress cephalogram revealed shortening of the ramus and opening of the mandibular plane consistent with condylar degeneration (Fig. 9.29). A diagnosis of idiopathic condylar resorption (ICR) was concluded and the patient placed in a mandibular stabilizing splint to be worn at night to reduce loading on the joints. The splint was not tolerated by the patient. Follow-up radiographs revealed ongoing degeneration of the joints consistent with ICR, a decrease in chin projection and increase in skeletal convexity, and relative retrognathism of the mandible with a significant anterior openbite37–40 (Figs. 9.30 and 9.31). Serial radiographs reflected relative stability of the maxillo-mandibular relationships and cessation of active degenerative stage of ICR. Facial evaluation revealed a symmetrical face with a convex profile and retrusive chin. The smile analysis revealed

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• Fig. 9.25  Intraoral (A–E) photos exhibit fixed appliances, three miniplates lateral to both upper left and

right molars and the lower left posterior teeth, and elastomeric chain to distal drive the posterior teeth from extension arms to facilitate a more translational tooth movement. As the posterior teeth were moved posteriorly, compressed coils were placed between the anterior teeth to facilitate restoration to their normal dimensions (F–J). The posterior occlusion was now near Class I and symmetrical (K and L).

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• Fig. 9.26  Intraoral (A–E) photos exhibit fixed appliances with provisional composite restorations to facilitate finishing of inciso-gingival positions and mesiodistal dimensions (A–E).

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Fig. 9.27  Posttreatment facial (A–C) and intraoral (D–H) photos exhibit pleasing changes to the smile esthetics after ceramic veneers to the upper anterior teeth and a good functional occlusion with restoration of symmetry.

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I • Fig. 9.28  Facial (A–C) and intraoral (D–H) photos exhibit a Class II type malocclusion in the early mixed dentition with upper midline deviation to

the right resulting from early loss of the upper right deciduous canine. The cephalometric radiograph reveals a mild Class II skeletal pattern with mild mandibular retrognathism (I), and the panoramic radiograph reveals relatively normal dental development and no apparent temporomandibular joint pathology (J).

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I • Fig. 9.29  Progress facial (A–C) and intraoral (D–H) photos exhibit development of a significant Class II

openbite-type malocclusion with the Nance button holding the space created by fixed molar distalizer. The cephalometric radiograph reveals a mild Class II skeletal openbite pattern with shortening of the posterior vertical ramus dimension (I). The panoramic radiograph reveals significant temporomandibular joint breakdown (J).

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I • Fig. 9.30  Progress facial (A–C) and intraoral (D–H) photos taken 24 months following initial recognition of the joint issues exhibit progression of Class II openbite type malocclusion. The cephalometric radiograph with Mesh template overlay reveals a significant Class II skeletal openbite pattern with shortening of the posterior vertical ramus dimension (I). The panoramic radiograph reveals significant temporomandibular joint breakdown (J).

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C • Fig. 9.31  The second progress cephalometric radiograph (A) and superimpositions (B) and panoramic radiograph (C) reveal continued breakdown/remodeling of the condylar head. This has contributed to worsening of the openbite and mandibular retrognathism.

relatively normal smile characteristics. Intraoral examination revealed a Class II type malocclusion with increased overjet, anterior openbite, and moderate crowding in the upper and lower anterior teeth (Fig. 9.32). Radiographic evaluation revealed a skeletal openbite relationship with short ramus height, reduced vertical development of the maxillary posterior alveolar heights, and a retrognathic, backward-rotated mandible. The panoramic radiograph revealed evidence of previous degenerative change and significant shortening of the condylar neck (see Fig. 9.32).

Problem List Condylar degeneration Anterior openbite Short ramus height Increased mandibular plane Convex profile Mandibular retrognathism

Upper and lower crowding Increased overjet

 Treatment Goals To close the openbite by counterclockwise rotation of the mandible and address the Class II relationship, chin retrusion, and retrognathic mandible by a combination of counterclockwise rotation and horizontal advancement of the mandible. The upper and lower teeth will be aligned and the anteroposterior position of the incisors retained on their respective skeletal bases. 

Considerations Ideally, a surgical plan should be considered from a morphologic perspective to rotate the maxillo-mandibular complex counterclockwise with simultaneous mandibular advancement. The presence of compromised condyles (ICR) makes this a relatively unstable procedure with the possibility of

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Fig. 9.32 Progress facial (A–C) and intraoral (D–H) photos reveal relatively stable facial and occlusal features with facial convexity and Class II openbite with upper and lower crowding that confirmed radiographic evidence of relative stability.

inducing postsurgical changes in the joints that could result in recurrence of the openbite and mandibular retrognathism.37–40 Simultaneous surgery to reposition the meniscus has been reported by several investigators to be stable,41,42 but many surgical teams throughout the world do not share the same optimism for the procedure. An alternative plan could consider skeletal anchors to simultaneously intrude and retract upper and lower posterior teeth.43,44 The vertical dimension will be reduced to close the openbite and rotate the mandible forward

and create space for alignment of the anterior teeth. This treatment plan would have minimal impact on the loading patterns on the condyles and certainly would be less invasive than orthognathic surgery with its associated limitations. 

Treatment Upper and lower third molar extractions scheduled simultaneously with placement of SAS plates buccal to

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• Fig. 9.33  Progress facial (A–C) and intraoral (D–H) photos following banding and bonding and placement

of four miniplates lateral to the upper and lower molars. Elastomeric chains were placed to intrude and independently retract the posterior teeth with extension arms on posterior segments to facilitate translatory distal movement. Note the rectangular lingual arches used to reduce lateral flaring of the posterior teeth from the intrusive forces (G and H). Incisor contact was achieved within 4 months.

upper and lower first molars. Upper and lower molars and premolars were banded with Burstone hinge-cap palatal and lingual attachments with 0.032 × 0.032-inch square lingual and palatal arches to control the transverse dimension while intrusive forces were applied from the SAS plates. Archwires progressed from 0.016 × 0.022 Niti archwires to 0.019 × 0.025-inch titanium molybdenum alloy (TMA) wires. Simultaneous retraction forces from the bone

plates were applied through extension arms on the upper wire to place the force as close to the center of resistance of the upper posterior teeth to minimize tipping on the unit. Within 4 months, the openbite had improved significantly (Figs. 9.33 and 9.34). Retraction and intrusion continued for a total of 9 months before appliances were placed on the anterior teeth and initial alignment wires of 0.016 Niti were placed (Fig. 9.35A–E).

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Fig. 9.34 Progress intraoral (A–E) photos with elastomeric chains to continue to retract and intrude the posterior teeth with extension arms on posterior segments to facilitate translatory distal movement. Progression of space creation is obvious (F–J). The force systems of independent retraction and intrusion are represented relative to the center of resistance of the posterior teeth (K).

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• Fig. 9.35  Progress intraoral photos at the time of bonding the remaining anterior teeth (A–E). Alignment was achieved using flexible nickel titanium archwires (F–J).

Five months after full banding, rectangular 0.016 × 0.022 Niti archwires were placed (Fig. 9.35F–H) progressing to 0.019 × 0.025-inch TMA wires. Intrusive and retraction forces were maintained throughout this period with the need to retract the upper arch to address a mild Class II tendency using extension arms to control the rotation (Fig. 9.36A–E). Finishing and detailing in the lower arch were performed with a round 0.018 steel archwire (Fig. 9.36F–J) and brackets removed 16 months after full fixed appliances were placed,

with a total treatment time of 25 months. Bonded upper and lower retainers and vacuum-formed removable retainers were constructed with small composite attachments placed on the labial of the upper anterior teeth to minimize any tendency for the incisors to relapse (Fig. 9.37). 

Summary The outcome from the treatment is excellent both esthetically and functionally, with several significant benefits from

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Fig. 9.36  Intraoral (A–E) photos exhibit fixed appliances in rectangular 19 × 25 titanium-molybdenum alloy (TMA) wires with elastomeric chain to distal drive the posterior teeth from extension arms to facilitate a more translational tooth movement. Finishing bends were then placed to complete the correction (F–J).

intruding the posterior teeth with SAS plates. These include closure of the openbite with counterclockwise rotation of the mandible, which simultaneously improved the Class II occlusal relationship and chin projection. The SAS plates were also able to facilitate space creation for alignment of

the crowded anterior teeth. Moreover, these changes were able to be achieved with minimal iatrogenic effects and risks that may have been encountered if a combined surgical plan was to be considered.

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• Fig. 9.37  Posttreatment facial (A–C) and intraoral (D–H) photos exhibit pleasing changes to the convexity of the facial profile as the mandible rotated

upward and the established alignment and occlusion that were most satisfactory. Cephalometric radiograph with superimposition reveals the significant intrusion of the lower posterior teeth and upward and forward rotation of the mandible (I and J).

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References 1. Burstone C: Application of bioengineering to clinical orthodontics. In Graber T, Vanarsdall R, Vig, K. editors. Orthodontics: current principles and techniques. St Louis, MO, 2005 Elsevier Mosby, 293–330. 2. Burstone CJ: The segmented arch approach to space closure, Am J Orthod 82:361–378, 1982. 3. Nanda R, Kuhlberg AJ: Biomechanics of extraction space closure. In Nanda R, editor: Biomechanics in clinical orthodontics, Philadelphia, PA, 1997, Saunders, 156–187. 4. Creekmore TD, Eklund MK: The possibility of skeletal anchorage, J Clin Orthod 17:266–269, 1983. 5. Roberts WE, Marshall KJ, Mozsary PG: Rigid endosseous implant utilized as anchorage to protract molars and close an atrophic extraction site, Angle Orthod 60:135–152, 1990. 6. Cornelis MA, Scheffler NR, De Clerck HJ, Tulloch JF, Behets CN: Systematic review of the experimental use of temporary skeletal anchorage devices in orthodontics, Am J Orthod Dentofacial Orthop 131:S52–58, 2007. 7. Konomi R: Mini-implant for orthodontic anchorage, J Clin Orthod 31:763–767, 1997. 8. Markic G, Katsaros C, Pandis N, Eliades T: Temporary anchorage device usage: a survey among Swiss orthodontists, Prog Orthod 15:29, 2014. 9. Jambi S, Walsh T, Sandler J, Benson PE, Skeggs RM, O’Brien KD: Reinforcement of anchorage during orthodontic brace treatment with implants or other surgical methods, Cochrane Database Syst Rev 8:CD005098, 2014. 10. Usmani T, O’Brien KD, Worthington HV, et al.: A randomized clinical trial to compare the effectiveness of canine lacebacks with reference to canine tip, J Orthod 29:281–286, 2002. 11. Freudenthaler JW, Haas R, Bantleon HP: Bicortical titanium screws for critical orthodontic anchorage in the mandible: a preliminary report on clinical applications, Clin Oral Implants Res 12(4):358–363, 2001. 12. Motoyoshi M, Hirabayashi M, Uemura M, Shimizu N: Recommended placement torque when tightening an orthodontic miniimplant, Clin Oral Implants Res 17:109–114, 2006. 13. Namburi M, Nagothu S, Kumar C, Chakrapani N, Hanumantharao CH, Kumar SK: Evaluating the effects of consolidation on intrusion and retraction using temporary anchorage devices—a FEM study, Prog Orthod 18:2, 2017. 14. Kravitz ND, Kusnoto B, Tsay TP, Hohlt WF: The use of temporary anchorage devices for molar intrusion, J Am Dent Assoc 138:56–64, 2007. 15. Moon CH, Lee DG, Lee HS, Im JS, Baek SH: Factors associated with the success rate of orthodontic miniscrews placed in the upper and lower posterior buccal region, Angle Orthod 78:101– 106, 2008. 16. Lee KJ, Park YC, Park JY, Hwang WS: Miniscrew-assisted nonsurgical palatal expansion before orthognathic surgery for a patient with severe mandibular prognathism, Am J Orthod Dentofacial Orthop 137:830–839, 2010. 17. De Clerck H, Cevidanes L, Baccetti T: Dentofacial effects of bone-anchored maxillary protraction: a controlled study of consecutively treated Class III patients, Am J Orthod Dentofacial Orthop 138:577–581, 2010. 18. Park HS: A new protocol of the sliding mechanics with microimplant anchorage (M.I.A.), Korean J Orthod 30:677–685, 2000. 19. Park HS, Jeong SH, Kwon OW: Factors affecting the clinical success of screw implants used as orthodontic anchorage, Am J Orthod Dentofacial Orthop 130:18–25, 2006.

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20. Cousley RRJ, Sandler PJ: Advances in orthodontic anchorage with the use of mini-implant techniques, B Dent J 3:E4, 2015. 21. Reynders R, Ronchi L, Bipat S: Mini-implants in orthodontics: a systematic review of the literature, Am J Orthod Dentofac Orthop 135(5):564.e1–564.e19, 2009. 22. Kuroda S, Yamada K, Deguchi T, Hashimoto T, Kyung HM, Takano-Yamamoto T: Root proximity is a major factor for screw failure in orthodontic anchorage, Am J Orthod Dentofacial Orthop 13:S68–73, 2007. 23. Papageorgiou SN, Zogakis IP, Papadopoulos MA: Failure rates and associated risk factors of orthodontic miniscrew implants: a meta-analysis, Am J Orthod Dentofacial Orthop 142:577–595, 2012. 24. Jung YR, Kim SC, Kang KH, et al.: Placement angle effects on the success rate of orthodontic microimplants and other factors with cone-beam computed tomography, Am J Orthod Dentofacial Orthop 143:173–181, 2013. 25. Sugawara J: Temporary skeletal anchorage devices: the case for miniplates, Am J Orthod Dentofacial Orthop 145(5):559–565, 2014. 26. Sugawara J, Nishimura N: Minibone plates: the skeletal anchorage system, Semin Orthod 11:47–56, 2005. 27. Bock N, Ruf S: Skeletal anchorage for everybody? A questionnaire study on frequency of use and clinical indications in daily practice, J Orofac Orthop 76:113–128, 2015. 28. Schätzle M, Männchen R, Zwahlen M, Lang NP: Survival and failure rates of orthodontic temporary anchorage devices: a systematic review, Clin Oral Implants Res 20:1351–1359, 2009. 29. Lam R, Goonewardene MS, Allan BP, Sugawara J: Success rates of a skeletal anchorage system in orthodontics: a retrospective analysis, Angle Orthod 88(1):27–34, 2018. 30. Faber J Morum T, Jamilia A, Eslami S, Leal S: Infection predictive factors with orthodontic anchorage miniplates, Semin Orthod 24(1):37–44, 2018. 31. Ludwig B, Glasl B, Kinzinger GSM, Lietz T, Lisson JA: Anatomical guidelines for miniscrew insertion: vestibular interradicular sites, J Clin Orthod 45:165–173, 2011. 32. De Clerck HJ, Cornelis MA, Cevidanes LH, Heymann GC, Tulloch CJF: Orthopedic traction of the maxilla with miniplates: a new perspective for treatment of midface deficiency, J Oral Maxillofac Surg 67:2123–2129, 2009. 33. Kircelli BH, Pektas ZÖ: Midfacial protraction with skeletally anchored face mask therapy: a novel approach and preliminary results, Am J Orthod Dentofacial Orthop 133:440–449, 2008. 34. Oral and Dental Expert Group. Therapeutic guidelines: oral and dental. Version 2. Melbourne: Therapeutic Guidelines Limited; 2012. 35. Thiruvenkatachari B, Harrison J, Worthington H, O’Brien K: Early orthodontic treatment for Class II malocclusion reduces the chance of incisal trauma: results of a Cochrane systematic review, Am J Orthod Dentofacial Orthop 148, 2015. 36. Tulloch JFC, Proffit WR, Phillips C: Outcomes in a 2-phase randomized clinical trial of early Class II treatment, Am J Orthod Dentofacial Orthop 125(6):657–667, 2004. 37. Arnett GW, Milam SB, Gottesman L: Progressive mandibular retrusion-idiopathic condylar resorption. Part II, Am J Orthod Dentofacial Orthop 110:117–127, 1996. 38. Handelman CS, Greene CS: Progressive/idiopathic condylar resorption: an orthodontic perspective, Semin Orthod 19(2):55– 70, 2013. 39. Sarver DM, Janyavula S, Cron RQ: Condylar degeneration and diseases—local and systemic etiologies, Semin Orthod 19(2):89– 96, 2013.

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40. Wolford LM: Can orthodontic relapse be blamed on the temporomandibular joint? J Orthod Sci 3(4):95–105, 2014. 41. Gonçalves JR, Cassano DS, Wolford LM, Santos-Pinto A, Márquez IM: Postsurgical stability of counterclockwise maxillomandibular advancement surgery: affect of articular disc repositioning, J Oral Maxillofac Surg 66:724–738, 2008. 42. Bodine TP, Wolford LM, Araujo E, Oliver DR, Buschang PH: Surgical treatment of adolescent internal condylar resorption (AICR) with articular disc repositioning and orthognathic surgery in the growing patient—a pilot study, Prog Orthod 17:2, 2016.

43. Alsafadi AS, Alabdullah MM, Saltaji H, Abdo A, Youssef M: Effect of molar intrusion with temporary anchorage devices in patients with anterior open bite: a systematic review, Prog Orthod 17:9, 2016. 44. Mariani L, Maino G, Caprioglio A: Skeletal versus conventional intraoral anchorage for the treatment of class II malocclusion: dentoalveolar and skeletal effects, Prog Orthod 15:43, 2014.

PART V

Zygomatic Implants

10. Zygomatic Miniplate-Supported Openbite Treatment: An Alternative Method to Orthognathic Surgery   Nejat Erverdi and Çağla Şar 11. Zygomatic Miniplate-Supported Molar Distalization   Nejat Erverdi and Nor Shahab

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10

Zygomatic Miniplate-Supported Openbite Treatment: An Alternative Method to Orthognathic Surgery NEJAT ERVERDI, ÇAĞLA ŞAR

Openbite Malocclusion and Treatment Anterior openbite is defined as a lack of anterior overlap of the incisors and can be considered as one of the most challenging malocclusions to treat. Numerous etiologic factors contribute to the development of this malocclusion, including: heredity, functional disorders, unfavorable growth patterns, functional habits, and trauma. According to Proffit, tongue thrust swallowing has too short a duration to have an impact on tooth position.1 During a swallow, tongue pressure against the teeth only lasts for 1 second. An individual swallows 800 to 1000 times in one day, which totals a few minutes. This duration is not enough to affect the equilibrium and cause an anterior openbite. Tongue thrust swallowing is a physiologic adaptation to an anterior openbite. On the other hand, a long-term forward or abnormal tongue posture can exert a continuous light force, preventing anterior teeth from erupting and may be an etiologic factor for anterior openbite malocclusion. Furthermore, if the position of the tongue is not normal, the pattern of resting pressure is also abnormal. The tongue is generally positioned above the occlusal surfaces of the lower posterior teeth and prevents their eruption. Thus the upper posterior teeth erupt, since they do not have occluding contacts and the mandible rotates backward. Anterior openbite can be classified as dental, skeletal, or a combination of these two. In a dental openbite, the malocclusion is limited to dental changes. Characteristics that have been found to be associated with skeletal anterior openbite include: decreased posterior facial height, increased anterior lower facial height, increased mandibular plane angle, increased maxillary posterior dentoalveolar height, Class II tendency, and clockwise rotation of the mandible.2,3 Furthermore, inadequate lip seal and weak orofacial muscles accompany the skeletal openbite malocclusion. Several treatment approaches have been advocated for the treatment of anterior openbite.4,5 These approaches comprise:

habit breakers, posterior bite blocks, high pull headgears, anterior vertical elastics with fixed appliance orthodontic treatment, multiloop edgewise archwire technique,6,7 curved arches with vertical elastics, and step-down/step-up archwire bends. The treatment method should be based on the malocclusion’s etiologic traits. Dental anterior openbite treatments focus on eliminating the functional habit, erupting maxillary and mandibular anterior teeth with fixed orthodontic mechanics, and wearing vertical interarch elastics. If the openbite is caused by the abnormal posture of the tongue, the treatment modality should focus on increasing the area of the tongue. The size of the tongue can be considered as actual or relative. Adenoidectomy and tonsillectomy increase the area of the tongue relative the oropharyngeal space, while rapid maxillary expansion and partial glossectomy actually increase the oropharyngeal space in relationship to the tongue area. Partial glossectomy should only be performed if the patient has a macroglossia. Diagnostic criteria of macroglossia include the positioning of the tongue apex outside the dentition, indentations of the teeth on tongue border and labial/buccal tipping of teeth. If the tongue size is normal but appears large, it can be caused by a habitual forward posturing, hypertrophied tonsils/adenoid tissue, low palatal vault, and small arches.4,8 In a skeletal anterior openbite growth pattern, more posterior-superior growth of the condyle, lack of forward internal rotation of the mandible, lack of posterior facial height development, vertical eruption of maxillary molars, and more downward position of the maxilla are seen. Most common morphologic pattern is posterior maxillary dentoalveolar excess and clockwise rotation of the mandible.4,5 Therefore the aim of the treatment modality should include intrusion of the maxillary posterior dentoalveolar segments. This treatment approach leads to a displacement of the tongue’s root downward, positions the tongue downward and backward, and corrects the altered functional matrix. Subsequently, the mandible rotates counterclockwise 149

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(CCW) and the openbite closes. Many attempts have been made to intrude maxillary posterior teeth. True intrusion of the maxillary posterior dentoalveolar segment and the maxilla can be accomplished with orthognathic surgery, which is a widespread and proven approach. However, patients who undergo orthognathic surgery usually have a long and difficult postoperative healing period. Therefore pros and cons of surgical treatment should be considered carefully. With the introduction of temporary anchorage devices in orthodontics, minimally invasive treatment options became possible for the treatment of anterior openbite.9 Umemori et al. placed L-shaped titanium miniplates on the mandibular corpus area for the intrusion of mandibular posterior segment in 1999.10 Alternatively, in 2002, Erverdi et al. were the first researchers who used the zygomatic buttress area as an anchorage site and placed titanium miniplates to zygomatic process of the maxillary bone for the intrusion of the maxillary dentoalveolar segment.11 The technique requires a minimally invasive surgery, which can be performed under local anesthesia. The zygomatic buttress has been proven to be a safe area, where temporary anchorage devices have been placed for many years. Erverdi,11–13 Sherwood,14,15 LentiniOliveira,5 and Scheffler16 have used zygomatic anchorage for maxillary posterior teeth intrusion and connected miniplates directly to molars and premolars on segmental fixed appliances. Having seen the buccal tipping of posterior teeth with the use of these mechanics, Erverdi et al.17 modified the appliance and the technique. This chapter describes the skeletal openbite treatment with the new generation openbite appliance (OBA) and zygomatic anchorage, which can be an alternative to orthognathic surgery. Moreover, cases treated with this technique are presented. 

Zygomatic Anchorage: Multipurpose Implant The zygomatic buttress has been proven to provide sufficient anchorage for significant orthodontic tooth movements, such as maxillary posterior dentoalveolar intrusion and enmasse distalization of the entire maxillary arch. The zygomatic process is a safe region, since it has the thickest cortical bone in the maxilla. Besides, it is away from the roots of the teeth, and is frequently used for anchorage.18 Complex malocclusions, which are challenging to treat with conventional orthodontic mechanics, can be predictably treated with the use of titanium miniplates. In the past, miniplates used for maxillofacial surgery, were also used for orthodontic anchorage. More recently, titanium miniplates for specific orthodontic purposes have been introduced to the market with different designs. The Multipurpose Implant (MPI), developed by Dr. Erverdi (Tasarim Med, Istanbul, Turkey), has two main components: the retentive and the extension sections (Fig. 10.1). The retentive section consists of three holes for fixation of the screws. Diameter of the holes is 2.3 mm, and screws 5, 7, and 9 mm of length are used to secure the plate into the bone according to the thickness of the

• Fig. 10.1  Multipurpose Implant (MPI) with retentive part and bendable part.

anatomic structures. The extension section or extension arm is 20 mm long and has a round cross-section made out of titanium, which is bendable. Since the desired tooth movement may vary in many cases, the extension part can be bent accordingly to deliver the necessary force vectors. The center of resistance (CR) of the maxillary posterior segment to be intruded passes approximately through the mesial root of the upper first molar and zygomatic buttress area (Fig. 10.2). Therefore the zygomatic region seems to be the most suitable place as an anchorage site for maxillary posterior dentoalveolar intrusion. The force vector provides parallel intrusion of the segment. In cases where first premolar extractions are performed, CR of the posterior segment moves slightly distally (Fig. 10.3). Thus a slight distal step is bent on the long extension of the miniplate.

Surgical Method for Multipurpose Implant Placement Surgical placement of MPI is performed under local anesthesia. Following infiltration, a vertical incision is made in the vestibule, by digital palpation along the zygomatic buttress. The ideal position has to take into consideration that the extension arm of the miniplate should penetrate the soft tissue mucosa from the bone through the keratinized attached gingiva at the mucogingival junction. Therefore the lower border of the incision should be at the intersection of the attached gingiva and mobile mucosa. The mucoperiosteum is released and the area is prepared for fixation. MPI is bent precisely according to the shape of the zygomatic buttress. The extension arm of the miniplate is cut into the proper length and bent to form a hook (Fig. 10.4). The miniplate has three holes; however, at least two mini-implants should be placed to avoid rotation.

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The position of MPI should be as high as possible into the zygomatic crest for two main reasons: attaining a better bone quality and increasing the distance between application point of skeletal anchorage and the teeth. Since the desired movement in this case is intrusion, adjusting the amount of force would be easier when the distance is long. However, retraction of soft tissues and insertion of upper screws of MPI may be technically challenging in some cases. Following the insertion of the miniplates and miniimplants, the incision is sutured. Following surgery, antiinflammatory agents, analgesics, and chlorhexidine gluconate are prescribed. 

Possible Complications

•

Fig. 10.2 Center of resistance (CR) of maxillary posterior segment passes through the mesial root of the first upper molar.

Some complications may be encountered following surgery. If the width of the attached gingiva is too narrow, the emergence point of the miniplate may be through the mobile mucosa. In such cases, soft tissue irritation and postoperative inflammation can be observed, which lead to mobility of the miniplate. Postsurgical swelling and pain are the most frequent complications reported by the patients. The inflammatory symptoms and changes persist for 5 to 7 days. Inflammation can be observed in any phase of the treatment. In such cases, force application should be stopped and antibiotic treatment should be initiated together with a chlorhexidine mouthwash. Patients should be informed about maintaining their oral hygiene properly. Healing period is approximately 15 days. Following healing, force can be reapplied. Other complications that may be seen during surgery, postoperatively and during orthodontic treatment, include: root damage and sinus perforation, soft tissue, cheek and lip irritation, gingival dehiscence, and anchor breakage. 

Removal of Multipurpose Implant

• Fig. 10.3  In cases with first premolar extractions, center of resistance (CR) of posterior segments shifts slightly posterior to the distal root of the first molar.

Removal of the miniplate again requires a mucoperiosteal incision under local anesthesia. There may be some bone deposition around the miniplates and screws. Following removal of the bone, granulation tissues should be removed. The screws should be loosened with the help of screw drivers, and the incision is sutured. 

• Fig. 10.4  Surgical procedure for Multipurpose Implant (MPI) placement. Vertical incision is done along the zygomatic buttress. MPI is bent according to the shape of the zygomatic buttress and fixed with three mini-implants. The extension arm is cut in proper length and bent distally to form a hook.

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• Fig. 10.5  Fabrication of the openbite appliance. Palatal arches are bent on two layers of wax. The orienta-

tion of the buccal bars should be transversally adjusted in such a way that the vector of force application is parallel to the long axis of the molars. The right and left acrylic bite blocks are connected with palatal bars and cover the occlusal surfaces of the teeth.

New-Generation Openbite Appliance The OBA was first introduced in 2006 by Dr Erverdi.13 It has been modified over time based on clinical experience.

Fabrication Wire Bending The openbite appliance consists two acrylic bite blocks connected with two palatal bars, made of 1.5-mm round stainless steel wire. These bars should be away from the palatal mucosa. To avoid the impingement of the appliance to palatal mucosa during intrusion, two layers of wax are placed to the palatal side of the model. Buccal bars are used for force application and are made from 0.8-mm

round stainless steel wire. They extend from first premolar to second molar. Nickel titanium closed coil springs are attached to the wires before embedding the wires into the acrylic (Fig. 10.5). The orientation of the buccal bars should be transversally adjusted in such a way that the vector of force application is parallel to the long axis of the molars when the coil springs are attached to the multipurpose miniplates. Another advantage is that they can be bent downward to increase the vertical dimension and allow for additional activation. 

Acrylic Cap The right and left acrylic bite blocks are connected with palatal bars. They cover the occlusal surface of the posterior

CHAPTER 10  Zygomatic Miniplate-Supported Openbite Treatment: An Alternative Method to Orthognathic Surgery

153

• Fig. 10.6  Intraoral application of coil springs from the openbite appliance to the hooks of Multipurpose Implant.

Cm2

0.70

0.80

0.30

0.30

0.45

0.30

0.40

150-g/cm2 100-g/cm2

105 70

120 80

45 30

45 30

65 45

45 30

60 40

100-g/cm2 150-g/cm2

75 110

85 130

30 45

30 45

35 50

20 30

20 30

0.75

0.85

0.20

0.20

Cm2

0.30

0.30

0.35

• Fig. 10.7  Ricketts’ chart for calculation of force magnitude.

teeth to be intruded. The thickness should be at least 4 mm or greater to impinge into the freeway space. Occlusal surfaces should contain holes to provide retention during bonding the appliance to posterior teeth. 

Clinical Application The OBA should be tried in the mouth to check the fit before bonding. Acrylic bite blocks should contact all posterior teeth equally. Primary contacts are trimmed after evaluating bite closing and eccentric movements to eliminate occlusal interferences. The appliance is bonded with

glass ionomer cement. Following the removal of sutures on the seventh day of MPI placement, two 9-mm Niti coil springs are attached from the buccal bars to the hook of the miniplate and a total of 400-g (200-g per side) is applied (Fig. 10.6). The intrusive force has three components functioning in the same favorable way to intrude the maxillary posterior teeth. Niti coil springs using bilateral intrusive force are the main components of this system. Calculation of the force magnitude is determined according to the chart developed by Ricketts (Fig. 10.7). The buccal bars are located on the same plane as the multipurpose miniplates, allowing the

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• Fig. 10.8  Schematic illustration of the system. Combination of three intrusive force vectors are present with the openbite appliance. Small black arrows: intrusive force from the acrylic cap; Large black arrows: intrusive force from the tongue; Gray arrows: intrusive force from the closed nickel titanium coil springs.

force to be transmitted directly. The acrylic cap is a very advantageous component to transmit the forces from muscle tonus and chewing functions directly to the posterior teeth. Furthermore, the palatal bar in contact with the tongue is the third component that transmits the intrusive force to the teeth (Fig. 10.8). 

Retention of Openbite Treatment Retention of the anterior openbite correction can often be quite difficult. Muscle exercises are recommended together with canine-to-canine fixed lingual retainers. The easiest way to improve muscle tone is to chew natural sugar-free chewing gum 3 to 4 hours daily in the first 3 months of retention. This type of gum is odorless, tasteless, and hard. Fixed lingual retainers can prevent recurrence of the crowding, but they cannot prevent the relapse of anterior openbite if the abnormal tongue position is still present. 

Clinical Experience This treatment should only be applied to patients with very good oral hygiene. The areas where the implant is exposed in the mouth should be cleaned very well, and the patients must comply with oral hygiene requirements throughout treatment. Upper third molars should be extracted before starting the treatment.

The first stage of treatment includes the closure of the anterior openbite with OBA. It takes approximately 5 to 6 months. The appliance is removed following the openbite correction and autorotation of the mandible. In some cases, the position of the incisors may not allow the mandible to fully autorotate after OBA removal. In such cases, upper incisors should be leveled and proclined during the intrusion phase of treatment. To do this, the acrylic on the buccal side of the first premolar is removed and brackets are bonded to upper teeth including incisors, canines, and first premolars. When the underlying skeletal malocclusion has been corrected with OBA, fixed orthodontic treatment is started, which is the second stage of treatment. The first molars should be ligated to the multipurpose implant to maintain the vertical position of the molars until the end of the treatment. 

Case Report 1 Case Summary A 25-year-old male patient presented with a convex skeletal soft tissue profile because of a retrognathic mandible. He had Class II canine and Class I molar relationships on both sides, an anterior openbite, increased mandibular plane angle, and increased lower anterior facial height. Posterior maxillary dentoalveolar heights were excessive (Fig. 10.9). 

CHAPTER 10  Zygomatic Miniplate-Supported Openbite Treatment: An Alternative Method to Orthognathic Surgery

• Fig. 10.9  Pretreatment facial and intraoral photographs.

Problem List Dimension Anteroposterior

Vertical

Transverse

 

Skeletal Convex skeletal profile caused by retrognathic mandible. Skeletal Class II Increased lower anterior facial height Increased mandibular plane angle Increased maxillary posterior dentoalveolar heights

Dental Overjet: 5 mm Class II canine relationship

Soft Tissue Retrusive lower lip and chin

Overbite: −4 mm Flat maxillary smile arc

Active mental muscle while closing the lips and the mouth Large interlabial gap

Slight crossbite tendency on the right buccal segment Mandibular midline 1 mm to the right of facial midline

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Treatment Objectives Dimension Anteroposterior

Skeletal Reduce skeletal convexity with autorotation of the mandible in counterclockwise direction Reduce lower facial height and mandibular plane angle by intruding the maxillary posterior teeth and autorotating the mandible

Vertical

Transverse

Dental Improve overjet by autorotation of the mandible

Soft Tissue Improve soft tissue profile

Improve anterior overbite and smile arc by intruding upper posterior teeth and maintaining the vertical position of the anterior teeth.

Reduce interlabial gap Improve the profile by intruding maxillary dentoalveolar sites. Achieve the closure of the lips without activation of the mental muscle.

Correct crossbite tendency on the right buccal segment Move mandibular midline 1 mm to the left

 

Treatment Plan The treatment of a skeletal openbite requires skeletal or dentoalveolar impaction of maxillary posterior segment to address the etiology of the malocclusion. Skeletal impaction could only be obtained by orthognathic surgery. As an alternative to orthognathic surgery, zygomatic miniplate–supported maxillary posterior dentoalveolar impaction could be used. 

Treatment Sequence Zygomatic miniplates were placed under local anesthesia. The OBA appliance was cemented 1 week after the surgery. Two 9-mm-length Niti closed coil springs were ligated bilaterally between the appliance and the tip of the MPI (Fig. 10.10). The intrusive force was 200-g on each side. Appointments were scheduled every 4 weeks and the progress was observed. Following the intrusion of maxillary posterior teeth, fixed orthodontic treatment was initiated (Figs. 10.11 and 10.12). The first molars were ligated tightly to the implants, to maintain intrusion throughout

•

fixed orthodontic treatment. Following detailing of the occlusion, brackets were removed and fixed lingual retainers bonded on both arches. The patient was instructed to chew hard chewing gum 2 hours a day for retention. 

Treatment Results At the end of treatment, Class I canine molar relationships were achieved. Anterior openbite was corrected by intruding maxillary posterior dentoalveolar segment, and mandibular plane angle showed CCW rotation (Fig. 10.13). 

Case Report 2 Case Summary A 21-year-old patient presented with a chief complaint of anterior openbite. She had a convex skeletal and soft tissue profile with retrognathic mandible. Molar and canine relationships were Class II on both sides. She exhibited a 5-mm anterior openbite and 4-mm overjet. Mandibular plane angle and anterior lower facial height were increased. The smile arch was not in consonance with the lower lip curve (Fig. 10.14). 

Fig. 10.10 Application of force with closed coil springs from openbite appliance to the hooks of the zygomatic miniplates.

• Fig. 10.11  End of intrusion mechanics.

A

B

C • Fig. 10.12  Fixed orthodontic treatment following the intrusion stage.

Upper molars are ligated to zygomatic miniplates throughout the second phase of treatment. (A) Intraoral right lateral view; (B) intraoral frontal view; (C) intraoral left lateral view.

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• Fig. 10.13  Posttreatment facial and intraoral photographs.

CHAPTER 10  Zygomatic Miniplate-Supported Openbite Treatment: An Alternative Method to Orthognathic Surgery

• Fig. 10.14  Pretreatment facial and intraoral photographs.

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Problem List Dimension Anteroposterior

Skeletal Convex skeletal profile caused by retrognathic mandible

Vertical

Increased lower anterior facial height Vertical overgrowth of the maxillary posterior dentoalveolar regions Narrow maxilla

Transverse

Dental Overjet: increased flared maxillary incisors Class II molar and canine relationship Overbite: −5 mm Reverse maxillary smile arc

Soft Tissue Retrusive lower lip and chin

Increased lower anterior soft tissue height Increased gingival maxillary display on the posterior segments

Broad mandibular arch Dental crossbite on the right buccal segment Lower midline 1 mm to the right of facial midline

 

Treatment Objectives Dimension Anteroposterior

Vertical

Transverse

Skeletal Reduce skeletal convexity with autorotation of the mandible in counterclockwise direction Reduce lower facial height and mandibular plane angle by intruding the maxillary posterior teeth and autorotating the mandible Maintain transverse skeletal dimension. Expand maxillary arch dentally

Dental Reduce excessive overjet by autorotation of the mandible

Soft Tissue Improve soft tissue profile

Improve anterior openbite and smile arc by intruding upper posterior teeth and maintaining the vertical position of the anterior teeth. Correct crossbite on right buccal segment Move mandibular midline to the left

Improve the profile by intruding maxillary dentoalveolar sites.

 

Treatment Plan The anterior openbite was planned to be corrected by intruding maxillary posterior teeth, allowing the mandible to autorotate in a CCW direction. In the present case, the amount of incisor display was normal. Therefore extrusion of upper incisors was to be avoided. The intrusion of posterior maxillary dentoalveolar regions was planned to be performed using zygomatic miniplates. 

Treatment Sequence The OBA appliance was cemented following the surgical insertion of multipurpose miniplates. At day 7, two 9-mm-­ length Niti coil springs were attached bilaterally between the appliance and the tip of the MPI. Appointments were scheduled every 4 weeks and the progress was observed. Following the intrusion of posterior dentoalveolar regions,

fixed orthodontic treatment was initiated. The first molars were ligated tightly to the miniplates, to maintain intrusion throughout the second phase of treatment. Following detailing of the occlusion, the brackets were debonded and fixed lingual retainers were bonded on both arches. The patient was instructed to chew hard chewing gum 2 hours a day. 

Treatment Results At the end of the treatment, Class I canine molar relationships were achieved (Fig. 10.15). Overjet was reduced to ideal, and correction of anterior openbite was achieved by intruding maxillary posterior dentoalveolar segment. Posterior gingival maxillary excess was corrected. Cephalometrically, mandibular plane angle showed CCW rotation (Figs. 10.16 and 10.17).

CHAPTER 10  Zygomatic Miniplate-Supported Openbite Treatment: An Alternative Method to Orthognathic Surgery

• Fig. 10.15  Posttreatment facial and intraoral photographs.

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A

B

C

D •

Fig. 10.16  Initial and final panoramic and cephalometric radiographs. (A) Pre-treatment cephalometric radiograph; (B) pre-treatment panoramic radiograph; (C) post-treatment cephalometric radiograph; (D) post-treatment panoramic radiograph.

• Fig. 10.17  Cephalometric superimposition. Significant autorotation of the mandible with maxillary posterior segment intrusion.

References 1. Proffit W, Fields H: Contemporary orthodontics, ed 5, St Louis, 2013, Mosby, p 413. 2. Subtelny JD, Sakuda M: Open bite diagnosis and treatment, Am J Orthod 50:337–358, 1964. 3. Ngan P, Fields H: Open bite: a review of etiology and management, Pediatr Dent 19:91–98, 1997.

4. Cozza P, Mucedero M, Baccetti T, Franchi L: Early orthodontic treatment of skeletal open-bite malocclusion: a systematic review, Angle Orthod 75(5):707–713, 2005. 5. Lentini-Oliveira DA, Carvalho FR, Rodrigues CG, et al.: Orthodontic and orthopaedic treatment for anterior open bite in children (Review), Cochrane Database Sys Rev 9:Art No: CD005515, 2014. 6. Kim YH: Anterior openbite and its treatment with multiloop edgewise archwire, Angle Orthod. 57(4):290–321, 1987. 7. Kucukkeles N, Acar A, Demirkaya A, Evrenol B, Enacar A: Cephalometric evaluation of open bite treatment with NiTi archwires and anterior elastics, Am J Orthod Dentofacial Orthop 116:555–562, 1999. 8. Erverdi N. Çağdaş Ortodonti, 1st ed. Istanbul: Quintessence Yayıncılık;2017; 33–34. 9. Park HS, Kwon OW, Sung JH: Nonextraction treatment of an open bite with microscrew implant anchorage, Am J Orthod Dentofacial Orthop 130(3):391–402, 2006. 10. Umemori M, Sugawara J, Mitani H, Nagasaka H, Kawamura H: Skeletal anchorage system for open-bite correction, Am J Orthop 115:166–174, 1999. 11. Erverdi N, Tosun T, Keles A: A new anchorage site for the treatment of anterior open bite: zygomatic anchorage case report, World J Orthod 3:147–153, 2002. 12. Erverdi N, Keles A, Nanda R: The use of skeletal anchorage in open bite treatment: a cephalometric evaluation, Angle Orthod 74:381–390, 2004. 13. Erverdi N, Üşümez S, Solak A: New generation open-bite treatment with zygomatic anchorage, Angle Orthod 76:519–526, 2006.

CHAPTER 10  Zygomatic Miniplate-Supported Openbite Treatment: An Alternative Method to Orthognathic Surgery

14. Sherwood KH, Burch JG, Thompson WJ: Closing anterior openbites by intruding molars with titanium miniplate anchorage, Am J Orthod Dentofacial Orthop 122:593–600, 2002. 15. Sherwood KH, Burch JG, Thompson WJ: Intrusion of supererupted molars with titanium miniplate anchorage, Angle Orthod 73:597–601, 2003. 16. Scheffler NR, Proffit WR, Phillips C: Outcomes and stability in patients with anterior open bite and long anterior face height treated

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with temporary anchorage devices and a maxillary intrusion splint, Am J Orthod Dentofacial Orthop 146(5):594–602, 2014. 17. Erverdi N, Üşümez S, Solak A, Koldaş T: Noncompliance openbite treatment with zygomatic anchorage, Angle Orthod 77:986– 990, 2007. 18. Sugawara J, N M: Minibone plates: the skeletal anchorage system, Semin Orthod 11(1):47–56, 2005.

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11

Zygomatic Miniplate-Supported Molar Distalization NEJAT ERVERDI, NOR SHAHAB

Conventional noncompliance appliances rely exclusively on intraoral anchorage for molar distalization.1,2 Whereas these appliances incorporate design components to attempt to prevent anchorage loss, flaring of the anterior teeth and increased overjet usually take place to a significant extent. One negative consequence usually seen with these appliances is the increase of the lower facial height because of clockwise mandibular autorotation as the posterior teeth distalize.2–5 In addition, relapse of molar distalization is commonly seen, since the molars are used as anchorage to support the second phase of distalization consisting of the retraction of the premolars and incisors. To eliminate such complications, various intraoral distalizing mechanics combined with temporary anchorage devices (TADs) have been used, as it is possible to distalize the maxillary molars without anchorage loss by using absolute anchorage predictably and efficiently. Many patients seeking orthodontic treatment have complete dentitions; therefore no available alveolar bone sites are present for mini-implant placement to allow uninterrupted molar distalization without TAD replacement for the retraction of the premolars and incisors. Consequently, several studies have looked at extra-alveolar alternative sites, such as the hard palate, the mandibular retromolar area, the inferior border of the zygomatic buttress, and the mandibular symphysial region.6 The inferior border of the zygomatico-maxillary buttress provides a very suitable anatomic site for TAD placement as direct access is easy and it is away from critical anatomic structures. Because it is close to the maxillary molars, the zygomatic buttress can be used for their anchorage either

Dentaurum stop tube, stop screw and activator tube assembled

directly or indirectly.7,8 Zygomatic miniplates are easily placed and removed under local anesthesia and can be used in various clinical situations. This chapter describes the treatment strategy and outcomes of zygomatic miniplates and segmented archwires for maxillary molar distalization.

Method Description The use of mini-implants-supported zygomatic miniplates placed on the zygomatic buttress for anchorage is illustrated in Fig. 11.1. The body of the titanium miniplate (Multipurpose Implant, Tasarim Med, Istanbul, Turkey) consists of two holes made to receive two mini-implants for fixation. After the miniplates are fixated onto the zygomatic bone, the other end of the miniplate exits through the attached gingiva on the furcation level of the first molar. The miniplate placement surgery is performed under local anesthesia. One week later the sutures are typically removed after soft tissue healing is observed. Shortly after, the distalization procedure is started. Upper first premolars and second molars are bonded (Roth prescription 0.018-inch slot brackets), while the first molars are banded on the side of the distalization. The second premolar is usually not bonded during the initial distalization phase (Fig. 11.2). Following the leveling and alignment of the segment with nickel-titanium (Niti) archwires, a 0.016-inch stainless steel segmental wire is used together with 0.036-inch Niti open coil springs for the sliding mechanics. A stop tube with a stop screw (Dentaurum, Ispringen, Germany) that are attached to the extension arm of the miniplate, and an activator tube that receives the orthodontic wire (Dentaurum,

STD. mini-implants 2x7 mm Multipurpose implant

•

Fig. 11.1 Representation of the connecting system and miniplates applied. (With permission from DENTAURUM GmbH & Co. KG.)

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 Smile Analysis (Fig. 11.1.2) Smile arc Incisor display

Nonconsonant Rest: 2 mm Smile: 9 mm First premolar to second premolar Small Margins: irregular because of crowding Papilla: present

Lateral tooth display Buccal corridor Gingival tissue

Tooth size and proportion: normal Tooth Shape: normal Axial inclination: maxillary teeth inclined lingually Connector Space: normal Normal Upper dental midline is on with the facial midline and lower dental midline is 1.5 mm to the left.

Dentition

•

Fig. 11.2 Application of the zygomatic miniplate and distalization mechanics.

Ispringen, Germany) are linked together with a loop-shaped 1.1-mm thick stainless steel round wire, soldered at both ends by a dental technician (see Fig. 11.1). The modifiable loop design gives the operator the flexibility to adapt this part between the miniplate arm and teeth according to each patient’s anatomy, extending toward the archwire to transfer the point of force application to the level of the archwire. Maxillary molar distalization process starts 2 to 4 weeks after miniplate placement surgery. The patients are seen every 4 to 5 weeks to monitor progress, while the system is reactivated when needed by shifting the sliding lock toward distal or by placing a longer Niti open coil spring. Distalization is usually completed in approximately 4 to 6 months. 

Case 11.1

Pretreatment Extraoral Analysis (Fig. 11.1.1)

Facial height

Lips Nasolabial angle Mentolabial sulcus

 Intraoral Analysis (see Fig. 11.1.2) Teeth present

Molar relation Canine relation

A 16-year-old male patient with a chief complaint of upper and lower arch crowding had a convex profile with competent lips. Medical and dental history was noncontributory, and findings from a temporomandibular joint (TMJ) examination were normal with adequate range of jaw movements.

Facial form Facial symmetry Chin point Occlusal plane Facial profile

Incisal embrasure Midlines

Mesoprosopic No gross asymmetry noticed Coincidental with facial midline Normal Mild convexity because of a prognathic maxilla Upper facial height/lower facial height: normal Lower facial height/throat depth: normal Competent, upper: normal; lower: normal Increased Normal

Overjet Overbite Maxillary arch Mandibular arch

Oral hygiene

7654321/1234567 (Unerupted 8s) 7654321/1234567 (Unerupted 8s) Class I on the right, Class II on the left Class I on the right, Class II on the left 5 mm 5 mm U shaped, asymmetric and 2.5 mm of crowding U shaped with crowding of 4 mm and normal curve of Spee Fair

 Functional Analysis Swallowing Temporomandibular joint

Normal adult pattern Normal with adequate range of jaw movements

 Diagnosis and Case Summary A 16-year-old male patient with a chief complaint of upper and lower arch crowding presented with a convex profile with competent lips. He had a normal smiling line; upper teeth were inharmonious with the lower lip curve. Upper dental midline was on with the facial midline and lower

CHAPTER 11  Zygomatic Miniplate-Supported Molar Distalization

• Fig. 11.1.1  Pretreatment extraoral/intraoral photographs and panoramic radiograph.

Parameter

Norm

Value

SNA (°)

82

84

SNB (°)

80

78

ANB (°)

2

6

FMA (°)

24

29

MP-SN (°)

32

37

U1-NA (mm/°)

4/22

3.8/ 26

L1-NA (mm/°)

4/25

8.4/35

IMPA (°)

95

98

U1-L1 (°)

130

126

OP-SN (°)

14

16

Upper Lip – E Plane (mm)

-4

-2

Lower Lip – E Plane (mm)

-2

-0.1

Nasolabial Angle (°)

103

125

Soft Tissue Convexity (°)

135

124

• Fig. 11.1.2  Pretreatment lateral cephalogram with tracing and cephalometric analysis.

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dental midline was 1.5 mm to the left. The patient had Class I molar and canine relationship on the right, Class II molar and canine relationship on the left side. Cephalometric analysis revealed a Class II skeletal relationship, normal

vertical growth pattern with decreased upper and increased lower incisor inclinations. The amount of crowding was 2.5 mm and 4 mm in the maxillary and mandibular arches, respectively. 

Problem List Pathology/ others Alignment Dimension Vertical Anteroposterior

Irregular gingival margins of anterior teeth 2.5 mm of crowding present in maxillary arch 4 mm of crowding present in mandibular arch Skeletal Increased FMA Class II Convex profile caused by prognathic maxilla

Transverse

Dental Increased OB Class II molar and canine on left side Decreased upper and increased lower incisor inclinations Upper dental midline is on with the facial midline and lower dental midline is 1.5 mm to the left.

Soft Tissue Increased nasolabial angle

OB, Overbite; FMA, Frankfurt-Mandibular plane angle. 

Treatment Objectives Pathology/ Others Alignment

Monitor Distalize the upper left posterior segment to create space for alignment and achieve Class I occlusion Relieve crowding in both arches. Interdental stripping and retraction of mandibular incisors.

Dimension Vertical Anteroposterior Transverse

Skeletal

Dental Establish ideal overbite Correct Class II on the left side Match lower midline to facial midline

Soft Tissue

 Treatment Options In the maxillary arch, unilateral extraction of the left first/ second premolar with distalization of the left canine into Class I and protraction of the left side first molar into full cusp Class II could be an option in this case. A disadvantage of this option is that space closure could result in further retroclination of the maxillary incisors and midline deviation. A second option is distalization of the left side and buccal segment into Class I. Patient selected a nonextraction treatment option. In the mandibular arch, alignment could be performed by interproximal reduction and retraction of the flared mandibular incisors.)  • Fig. 11.1.3  Placement of the zygomatic miniplate on the left quadrant.

CHAPTER 11  Zygomatic Miniplate-Supported Molar Distalization

Treatment Sequence and Biomechanical Plan Maxilla Placement of miniplate on left quadrant (Fig. 11.1.3) Band upper first molars, bond 4s and 7s on the left side Sectional leveling 4–7 (5 is not bonded) with 0.012, 0.014, 0.016-inch Niti archwires Sliding mechanics on 0.016-inch SS wires (as described, Fig. 11.1.4) Continue until overcorrection of distalization is achieved Bond the rest of maxillary teeth and align with round Niti archwires (Fig. 11.1.5) Continue leveling with 0.016 × 0.016 and 0.016 × 0.022–inch Niti wires Continue to full size arch wires and finish Debond and place fixed lingual retainer, Essix 6-month recall appointment for retention check

Mandible

Bond mandibular teeth and align with Niti archwires Continue leveling with 0.016 × 0.016 and 0.016 × 0.022–inch Niti wires Continue to full size arch wires and finish Debond and place fixed lingual retainer, Essix 6-month recall appointment for retention check

• Fig. 11.1.4  Progress of segmental distalization treatment.

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• Fig. 11.1.5  Bonding of maxillary arch for alignment and refinement of the distalization if needed.

 Treatment Sequence Molar distalization with overcorrection was achieved efficiently in 4 months and 2 weeks without any anchorage loss and the treatment was followed with continuous archwires in upper and lower jaws. 

Final Results A very good occlusal and esthetic result was achieved while maintaining apical root integrity of the distalized teeth (Fig. 11.1.6). The amount of distalization for the maxillary left first molar was found to be 6.48 mm (Figs. 11.1.7 and 11.1.8), showing an amount of 1.44 mm distalization rate per month. This was accompanied by slight extrusion (0.82 mm), buccal displacement (0.55 mm) and distal tipping (6 degrees). There were no changes on the right quadrant. All maxillary teeth on the left side showed significant distalization amounts. The inclination of the maxillary incisors decreased by 4 degrees (see Fig. 11.1.8 and Fig. 11.1.9). Some vertical changes were observed on the incisors in reference to the occlusal plane, which were reflected on the overbite. The increase in the maxillary intercanine distance was registered to be 0.13 mm while the increase in the maxillary intermolar distance was 0.1 mm. The nasolabial angle was decreased by 1 degree according to soft-tissue cephalometric measurements (see Fig. 11.1.8). Mesial movement of the anchor teeth did not occur during distalization. However, there was 6 degrees of tipping as well as some distopalatal rotation of the left first molar with the buccal force application. When uprighting the molar later in the treatment, this will require some of the space

attained by distalization. Hence an overcorrection is recommended to compensate in these cases. Nevertheless, this protocol allowed effective noncompliance maxillary molar distalization without side effects.

What Was the Cause of This Asymmetrical Malocclusion in This Patient? Unilateral full-step Class II correction, with asymmetry in the maxillary arch, can pose a challenge for the orthodontist. The Class II subdivision malocclusion could be linked to early loss of a primary molar on the left side. Such situation can occur because of caries and no prevention plan regarding space retention in primary/mixed dentition. Various treatment modalities have been developed and used successfully over the years. Unilateral premolar extraction is usually an available treatment option but can cause arch skewing or displacement of the midline. It has been shown that a unilateral Class II malocclusion can be corrected by headgear with asymmetric face-bows but this needs serious cooperation from the patient. Moreover, the force delivery system unavoidably contains a lateral component that can result in a posterior crossbite. Distalization can also be performed with noncompliant mechanics, such as TADs with bone anchorage, which was our treatment of choice in this patient. 

Case 11.2 A 14-year-old female patient with a chief complaint of protruded upper teeth had a convex profile with competent lips. Medical and dental history was noncontributory, and findings from a TMJ examination were normal with adequate range of jaw movements.

CHAPTER 11  Zygomatic Miniplate-Supported Molar Distalization

• Fig. 11.1.6  Posttreatment extraoral/intraoral photographs and panoramic radiograph.

A

B • Fig. 11.1.7  Distalization magnitudes achieved on the left side (A) and accuracy of superimposition (B).

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A

B •

Fig. 11.1.8 (A) Posttreatment lateral cephalogram; (B) Superimposition. Blue, Pretreatment; red, posttreatment.

Facial form Facial height

6° 4°

0.82 mm

Nasolabial angle Mentolabial sulcus

 Smile Analysis (see Fig. 11.2.1)

6.48 mm

• Fig. 11.1.9  Schematic illustration of distalization results.

Pretreatment Extraoral Analysis (Fig. 11.2.1) Facial form Facial symmetry Chin point Occlusal plane Facial profile

Lips

Mesoprosopic Upper facial height/lower facial height: normal to low angle Lower facial height/throat depth: normal Competent, upper: normal; lower: normal Normal Normal

Mesoprosopic No gross asymmetry noticed Coincidental with facial midline Normal Mild convexity because of prognathic maxilla

Smile arc Incisor display

Lateral tooth display Buccal corridor Gingival tissue

Nonconsonant Rest: 3 mm Smile: 5 mm of gingival display starting from lateral incisors and extending towards posteriorly Second premolar to second premolar Normal Margins: uneven heights (central margins are apically placed) Papilla: present

CHAPTER 11  Zygomatic Miniplate-Supported Molar Distalization

Dentition

Incisal embrasure Midlines

Tooth size and proportion: normal Maxillary right central incisor has incisal edge restoration because of a previous trauma Tooth Shape: normal Axial inclination: maxillary teeth inclined lingually Connector Space: normal Normal Upper dental midline was on with the facial midline and lower dental midline was 1 mm to the left.

 Intraoral Analysis (see Fig. 11.2.1) Teeth present Molar relation Canine relation Overjet Overbite Maxillary arch Mandibular arch Oral hygiene

7654321/1234567 (Unerupted 8s) 7654321/1234567 (Unerupted 8s) Class II bilaterally Class II bilaterally 8 mm 0 mm U shaped, symmetric, 2.05 mm of crowding U shaped with crowding of 1.67 mm and normal curve of Spee Good

 Functional Analysis Swallowing Temporomandibular joint

Normal adult pattern Normal with adequate range of jaw movements

 Diagnosis and Case Summary A 14-year-old female patient with a chief complaint of protruded upper teeth had a convex profile with competent lips. She had a posterior gummy smile; upper teeth were nonconsonant with the lower lip curve together with lower incisor exposure. Upper dental midline was on with the facial midline and lower dental midline was 1 mm to the left. The patient had Class II molar and canine relationship on both sides. According to cephalometric analysis, she had a normal to low-angle growth pattern, Class I skeletal relationship (slightly prognathic maxilla, big mandible) with decreased upper and increased lower incisor inclinations (Fig. 11.2.2). The amount of crowding was 2.05 mm and 1.67 mm in the maxillary and mandibular arches, respectively. 

Problem List Pathology/others Irregular gingival margins of anterior teeth Posterior gummy smile Upper teeth are nonconsonant with the lower lip curve (reserve smile arc) Thin biotype of the labial periodontum of the mandibular incisors Alignment Dimension Vertical Anterioposterior

2.05 mm of crowding present in maxillary arch 1.67 mm of crowding present in mandibular arch Skeletal Normal to low-angle growth pattern Class II Prognathic maxilla

Transverse

Dental Reduced OB

Soft Tissue

Class II Decreased upper and increased lower incisor inclinations Upper dental midline on with the facial midline and lower dental midline 1 mm to the left.

OB, Overbite; FMA, Frankfurt-Mandibular plane angle. 

Treatment Objectives Pathology/others

Improve restoration of #11 postorthodontic treatment Monitor labial periodontum of the mandibular incisors

Alignment

Distalize and intrude upper posterior segments to achieve Class I occlusion and correct the posterior gummy smile Relieve crowding in both arches

Dimension Vertical Anteroposterior Transverse

Skeletal

173

Dental Improve overbite Correction of Class II relationship on both sides Correction of incisal inclinations, interincisal angle Correction of midline discrepancy

Soft Tissue

174 PA RT V    Zygomatic Implants

• Fig. 11.2.1  Pretreatment extraoral/intraoral photographs and panoramic radiograph.

Parameter

Norm

Value

SNA (°)

82

86

SNB (°)

80

80

ANB (°)

2

6

FMA (°)

24

26

MP-SN (°)

32

32

U1-NA (mm/°)

4/22

5.5/ 29

L1-NA (mm/°)

4/25

7.1/30

IMPA (°)

95

98

U1-L1 (°)

130

114

OP-SN (°)

14

17

Upper Lip – E Plane (mm)

-4

-3.5

Lower Lip – E Plane (mm)

-2

-2.3

Nasolabial Angle (°)

103

113

Soft Tissue Convexity (°)

135

122

• Fig. 11.2.2  Pretreatment lateral cephalogram with tracing and cephalometric analysis.

CHAPTER 11  Zygomatic Miniplate-Supported Molar Distalization

175

 Treatment Options

Treatment Sequence

In the present case, anterior and posterior teeth have slightly different occlusal planes that require correction by means of segmental mechanics. Two options are available: • Distalize and intrude upper posterior segment with zygomatic anchorage allowing some distalization of the whole buccal segment and clockwise rotation of the maxillary occlusal plane with some mandibular autorotation. Align arches and detail the occlusion. •  Extraction of maxillary premolars could also be an option; however, the patient selected a nonextraction treatment option. 

Molar distalization with overcorrection was achieved efficiently in 6 months without any anchorage loss. Slight buccal rotation of the maxillary left segment as distalization ensues (Fig. 11.2.4). This side effect is corrected by the placement of continuous archwires on the maxillary arch (Fig. 11.2.5). Once proper archform is achieved with rigid stainless steel archwires, any residual distalization is accomplished before the finishing stage. 

Treatment Sequence and Biomechanical Plan Maxilla Band upper first molars, bond 4s and 7s. Sectional leveling 4–7 (5 is typically not bonded; was bonded on the right in this case) with 0.012, 0.014, 0.016-inch Niti archwires (Fig. 11.2.3) Sliding mechanics on 0.016 SS wires (as described) Continue until overcorrection of distalization is achieved (see Fig. 11.2.3) Adjust vertical component of the miniplate to achieve some posterior intrusion Bond the rest of maxillary teeth and align with round Niti archwires Continue leveling with 0.016 × 0.016 and 0.016 × 0.022–inch Niti wires Continue to full size archwires and finish Debond and place fixed lingual retainer, Essix 6-month recall appointment for retention check

 

Mandible

Bond mandibular teeth and align with Niti archwires Continue leveling with 0.016 × 0.016 and 0.016 × 0.022–inch Niti wires Continue to full size archwires and finish Debond and place fixed lingual retainer, Essix 6-month recall appointment for retention check

Final Results Very good occlusal and esthetic results while maintaining apical root integrity were achieved through distalization as observed in the posttreatment photos and panoramic radiograph (Fig. 11.2.6). The amount of distalization for the maxillary right first molar was found to be 5.61 mm (Figs. 11.2.7 and 11.2.8), showing an amount of 0.94 mm distalization rate per month. This was accompanied by slight intrusion (1.35 mm), buccal displacement (2.61 mm) and mean distal tipping for both sides (5 degrees). Distalization of the maxillary left molar was 5.72 mm with intrusion (1.53 mm) and buccal displacement (1.88 mm). All maxillary teeth showed significant distalization amounts. The inclination of the maxillary incisors decreased by 5 degrees, reducing the overjet. There were some vertical changes observed on the incisors in reference to the occlusal plane, which increased the overbite. The increase in the maxillary intercanine distance was significant by 3.47 mm, while the increase in the maxillary intermolar distance was significant by 4.49 mm. The nasolabial angle was decreased by 4 degrees according to soft-tissue cephalometric measurements (see Fig. 11.2.7). Molar distal movement was achieved without active patient compliance and with no undesirable side effects, such as incisor proclination, clockwise mandibular rotation or root resorption. 

Conclusions Skeletal anchorage protocol is a very efficient treatment option for upper molar distalization with no side effects, such as anchorage loss and excessive protrusion of the anterior segment. This modifiable loop system gives the operator the flexibility to adapt the components according to the patient and adjust the force vector according to planned treatment objectives, such as some posterior intrusion in addition to distalization. Moreover, it offers the patient a treatment option without tooth extractions.

176 PA RT V    Zygomatic Implants

• Fig. 11.2.3  Distalization sequence with segmental mechanics.

CHAPTER 11  Zygomatic Miniplate-Supported Molar Distalization

• Fig. 11.2.4  Superimposition of maxillary arches before (green) and after (white) distalization.

• Fig. 11.2.5  Treatment progress postdistalization with placement of a continuous alignment wire in both arches.

177

178 PA RT V    Zygomatic Implants

• Fig. 11.2.6  Posttreatment extraoral/intraoral photographs and panoramic radiograph.

A •

B

Fig. 11.2.7 (A) Posttreatment lateral cephalogram; (B) Superimposition. Black, Pretreatment; red, posttreatment.

CHAPTER 11  Zygomatic Miniplate-Supported Molar Distalization

179

References

5° 5°

1.35 mm 5.61 mm

•

Fig. 11.2.8  Schematic illustration of distalization results for the right upper quadrant.

1. Bondemark L, Karlsson I: Extraoral vs intraoral appliance for distal movement of maxillary first molars: a randomized controlled trial, Angle Orthod 75:699–706, 2005. 2. Bussick TJ, McNamara Jr JA: Dentoalveolar and skeletal changes associated with the pendulum appliance, Am J Orthod Dentofacial Orthop 117:333–343, 2000. 3. Chiu PP, McNamara Jr JA, Franchi L: A comparison of two intraoral molar distalization appliances: distal jet versus pendulum, Am J Orthod Dentofacial Orthop 128:353–365, 2005. 4. Karlsson I, Bondemark L: Intraoral maxillary molar distalization, Angle Orthod 76:923–929, 2006. 5. Gelgör IE, Büyükyilmaz T, Karaman AI, Dolanmaz D, Kalayci A: Intraosseous screw-supported upper molar distalization, Angle Orthod 74:838–850, 2004. 6. Polat-Ozsoy O: The use of intraosseous screw for upper molar distalization: a case report, Eur J Dent 2:115–121, 2008. 7. Nur M, Bayram M, Celikoglu M, Kilkis D, Pampu AA: Effects of maxillary molar distalization with Zygoma-Gear Appliance, Angle Orthod 82:596–602, 2012. 8. Gianelly AA: Distal movement of the maxillary molars, Am J Orthod Dentofacial Orthop 114:66–72, 1998.

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PART VI

Buccal TADs and Extra-Alveolar TADs

12. Managing Complex Orthodontic Tooth Movement With C-Tube Miniplates Seong-Hun Kim, Kyu-Rhim Chung and Gerald Nelson 13. Application of Buccal TADs for Distalization of Teeth Toru Deguchi and Keiichiro Watanabe 14. Application of Extra-Alveolar Mini-Implants to Manage Various Complex Tooth Movements Marcio Rodrigues de Almeida

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12

Managing Complex Orthodontic Tooth Movement With C-Tube Miniplates SEONG-HUN KIM, KYU-RHIM CHUNG, GERALD NELSON

Introduction The use of orthodontic anchorage devices expands the possible treatment plan options. Temporary Skeletal Anchorage Devices (TSAD) have several advantages over more conventional methods, especially the design of simpler mechanics. We prefer the C-tube miniplates. Midline deviations require careful and sometimes complex biomechanical planning.1,2 A coincident midline is an important component of dental harmony, esthetics, and functional occlusion.3 If there is a skeletal component to the midline deviation, treatment planning becomes more complicated.4,5 When the choice is to do camouflage treatment for the facial asymmetry patient, good management of the dental midline is essential to a good esthetic outcome.6 Good biomechanical design for midline correction starts with a specific tooth movement goal. The best force systems provide efficient tooth movement with minimal side effects. A variety of treatment options has been reported for correcting dental midline discrepancy: asymmetric extraction, asymmetric mechanics, Class III elastics on one side and Class II elastics on the other, anterior diagonal elastics, or complex wire bending.7–10 The following two cases illustrate novel and simpler mechanics, using the C-tube as the anchorage device to correct a midline deviation. 

Methods In the mandibular arch, we used a C-tube miniplate (Jin Biomed co., Bucheon, Korea), manufactured from titanium grade II. This miniplate is smaller than other skeletal anchorage plates. The head part can receive a round or rectangular archwire, or be adapted as an elastic hook. The short I-type C-tube has a two-hole mounting base to accept screws and a preformed tube to accept an archwire. It is very useful in the posterior buccal area of the mandible or in the retromolar pad. In the cases described here, the I-type C-tube was a practical device to place on the facial surface of the symphysis to apply forces for buccal segment distalization and control of the vertical position of the lower incisors.

The I-shape design facilitates placement under local anesthesia. For example, the procedure for the facial placement is to retract the lip and make a vertical incision parallel to the tooth axis in the interdental space (Fig. 12.1A–C). Then the periosteum is elevated to allow direct contact between the bone and the mounting plate of the C-tube (Fig. 12.1D). Next, the C-tube miniplate is fixed with two monocortical mini-implants, first through the distal hole (1.5-mm diameter, 4-mm length). A correct position will bring the tube of the miniplate through the tissue at the mucogingival junction (Fig. 12.1E and F). Successful fixation to the facial bone of the symphysis may require bending and manipulating the mounting plate to adapt to the curves of the bone surface. Retention of the plate is enhanced by such close adaptation. The I-type design of the plate enables placement that avoids teeth roots and the mandibular nerve. Because the stalk of the head part is malleable, it can be positioned to enable the best biomechanical advantage. It is nevertheless rigid enough to remain stable under force application. The force application system described here will move posterior teeth distally on a rectangular wire that emerges from the miniplate tube. We term this design a C-tube pushing mechanism (Figs. 12.2 and 12.3). The force is developed via a compressed open coil spring, and the vector is parallel to the occlusal plane. The long lever arm that is inserted in the tube controls tipping very well. 

Clinical Report Case 1 A female patient, 25 years of age, presented with the chief complaint of mandibular anterior crowding. The mandibular third molar on the right was severely horizontally impacted. The molars and premolars mesial to the impaction were tipped mesially, displacing the canine into a Class III relationship with the upper canine. The mandibular anterior teeth were severely crowded. Aligning them would push all the lower incisors to the left, displacing the midline. Treatment objectives were to align the lower incisors, 183

184 PA RT V I    Buccal TADs and Extra-Alveolar TADs

A

B

C

D

E

F

•

Fig. 12.1  Surgical progress of I-type C-tube miniplate. (A) Checking the estimated position of C-tube before incision. (B) Making guide indentation with a dental explorer for more accurate placement. (C) Vertical incision made by a #15 blade with free-end in alveolar mucosa and no crossover in the mucogingival junction. (D) Full thickness of periosteal membrane was stripped with a periosteal elevator. (E) C-tube positioning and fixation by two 1.5 × 4-mm mini-implants. (F) After stabilizing the C-tube, adjusting the head according to the desired tooth movement with Weingart plier. (With permission from Jin Biomed co.)

upright and distalize the lower right buccal segment teeth into Class I, and achieve a lower midline coincident with the facial midline. Non-asymmetric extraction was avoided in preference to finishing with a normal occlusion. Four first premolars and the mandibular third molars were removed. Applying I-type C-tube on the anterior mandible provided vertical control of the mandibular incisors during retraction, and anchorage to distalize the mandibular right buccal segment (Fig. 12.4). The pretreatment maxillary midline was coincident with the facial midline, and the pushing mechanism was aided by the C-tube fixed to the facial bone of the symphysis. Mandibular incisor vertical control during space closure was achieved by tying a steel ligature wire from the C-tube head to the archwire (Fig. 12.5). 

Case 2 A 30-year-old male patient visited the orthodontic department with a chief complaint of edge-to-edge anterior occlusion (Fig. 12.6). There was a lower midline deficiency to the right combined with anterior and posterior crossbites. The target approach was distal movement of the right side. Push-type mechanics were used to the right side to move the molars distally. An I-type C-tube miniplate was placed on the buccal alveolar bone between the mandibular second premolar and first molar (Fig. 12.7B–E). After gaining adequate space to resolve the posterior crowding, traction

of anterior teeth started (Fig. 12.7F–I). The mandibular occlusal view demonstrates a significant amount of distal movement (Fig. 12.8). Posttreatment examination revealed a Class I molar and canine relationship on both sides, with good intercuspation. The midline was congruent with the facial midline (Figs. 12.9 and 12.10). 

Case 3 A female patient had a chief complaint of masticating problem on the left dentition. The patient had multiple problems on the left side of the occlusion. The lower left first molar was extracted a while back, and the lower first, second premolars, and second molar were mesiolingually inclined with extrusion. The maxillary left second premolar and first and second molar had extrusion including a collapsed occlusion with posterior deep bite and a crossbite. She also had anterior crossbite (Fig. 12.11). The treatment objectives were to correct the left collapsed occlusion while minimizing side effect movements of the anterior and right teeth. To accomplish this treatment goal, a segment archwire technique was applied (Fig. 12.12B). Fixed appliances were placed on selective posterior teeth with segmental approaches to control these independently. The C-tube miniplates were applied as skeletal anchorage. Two I-type C-tube plates were placed on the left maxilla buccolingually and one C-tube was placed in the retromolar area (Fig. 12.13). Each was

A

B

C

D • Fig. 12.2  C-tube assisted pushing method: prepare the anchorage against the C-tube to deliver pushing forces to the target teeth through open coil springs. (A) Placing C-tube on the mandibular buccal area and bonding solely target tooth. (B) Holding the rectangular wire passing through the attachment head hole and posterior bracket slot, first through the attachment head hole to easy placement of an open coil spring and then onto the bracket slot. (C and D) The lateral and occlusal view of push-type mechanics. (With permission from Jin Biomed co.)

A

C

B

D

E

• Fig. 12.3  C-tube assisted push-type method for mesially tipped third molar uprighting. (A) 017X025-in

stainless steel segmented archwire between C-tube and single tube on the third molar for uprighting; (B) open coil spring application for space regaining; (C) pretreatment x-ray; (D) uprighted third molar by C-tube assisted pushing method; (E) posttreatment x-ray. (With permission from Jin Biomed co.)

186 PA RT V I    Buccal TADs and Extra-Alveolar TADs

A

B

C

D •

Fig. 12.4  Clinical application of this novel method. (A–D) Intraoral photographs demonstrated C-tube miniplate on the symphysis with achieved midline correction by pushing the right posterior teeth distally. (With permission from Jin Biomed co.)

A

B • Fig. 12.5  Initial (A) and final (B) panoramic radiographs.

fixed with two drill-free mini-implants. After correction of the scissors-bite, an edgewise multibracket appliance was placed, and comprehensive orthodontic treatment was performed in both arches (Fig. 12.12C). Finishing and detailing of the occlusion were then performed to establish a solid functional occlusion with ideal overbite and overjet while providing prosthetic space for the lower left first molar. The collapsed occlusion was corrected without any side effects

on other teeth (Figs. 12.12D and 12.14). The occlusion was finished in Class II molar and Class I canine relationships with optimal overjet and overbite. Prosthetic treatment was continued to replace the lower left first molar (Fig. 12.15C). Posttreatment records 12 years later showed a stable treatment outcome. Serial panoramic radiographs showed that collapsed occlusion was improved and maintained well until 12 years later after treatment (Fig. 12.16). 

CHAPTER 12  Managing Complex Orthodontic Tooth Movement With C-Tube Miniplates

• Fig. 12.6  A 30-year-old male patient. Intraoral views. Patient reveals mesially positioned posterior teeth combined with deviation of midline that needs distalization and midline correction.

A

B

C

D

E

F

G

H

I

• Fig. 12.7  (A) Pretreatment. (B–F) I-type C-tube was placed on the buccal alveolar bone between the first

molar and second premolar. Push-type force delivery method started at the right posterior mandible initially applied to the bonded target teeth and later continued to the whole arch. (G and H) Space developed after pushing posterior teeth distally; retraction of anterior teeth was carried out by Class III elastics combined with traction forces anchored by the C-tube miniplate. (I) Final intraoral lateral view demonstrates acceptable occlusion. (With permission from Jin Biomed co.)

187

A

B

C

D • Fig. 12.8  A 30-year-old male patient. (A) Initial occlusal view displays severe anterior crowding on the right

resulting in a dental Class III occlusion that requires unilateral distalization. (B) Intraoral view depicts that just the target teeth were bonded. (C) Visually, it is clear to notice greater amount of distal movement of the second molar. (D) Aligned anterior teeth was observed in the final intraoral photograph.

A

B

C • Fig. 12.9  A 30-year-old male patient. (A) Initial panoramic radiograph reveals dental Class III occlusion that requires unilateral distalization. (B) Panoramic radiographs demonstrate that just the target teeth were bonded. (C) Great amount of distal movement of the second molar is noticed.

CHAPTER 12  Managing Complex Orthodontic Tooth Movement With C-Tube Miniplates

189

• Fig. 12.10 Intraoral photographs showing stable occlusion of a 30-year-old male patient after 3 years of retention.

• Fig. 12.11  Pretreatment records; intraoral photographs and cephalometric, panoramic radiographs.

Discussion Treatment of dental asymmetry can be very difficult, as it may require movement of the entire arch. Usually the first step of our alternative option to treat patients with dental asymmetry is to make space for the midline correction. It starts with molar distalization on the nondeviated side. Various conventional methods have been developed as a technique for molar distalization. However, those methods are accompanied by side effects, such as anterior movement of the premolars and incisors.11–13

The advent of TSADs, such as the mini-implants, have made it possible to move molars distally without forward movement of the anterior teeth.14–16 Although use of TSADs contributes to make an effective treatment plan, there are important considerations. To distalize a buccal segment, TSADs should provide biologically optimum stability, offer simple and comfortable hardware, and prevent side effects to the other teeth in the arch. The pushing mechanism in Cases 1 and 2 facilitate individual molar distalization with simple mechanics using the C-tube miniplate. Direct application of force from

190 PA RT V I    Buccal TADs and Extra-Alveolar TADs

A

B

C

D • Fig. 12.12  Treatment progress intraoral photos. (A) Pretreatment. (B) Preparation for target teeth move-

ment. Segmented archwires were applied on to target teeth. I-type C-tubes were used as skeletal anchorage on upper and lower buccal side and upper palatal side. Niti spring generates intrusive force on upper premolars and molar. On the lower arch, Niti spring induce labioversion with intrusion of lower premolars. (C) After target teeth movement, continuous archwire were applied. (D) Recovery of collapsed occlusion. (With permission from Jin Biomed co.)

A

B

C

D

• Fig. 12.13  Uprighting of mandibular second molar. (A and B) Installation of C-tube. (C and D) Elastomeric

material was used for intrusive buccal uprighting of second molar using a lingual button and C-tube head. (With permission from Jin Biomed co.)

• Fig. 12.14  Posttreatment records; intraoral photographs.

A

B

C

D • Fig. 12.15  Serial intraoral photographs. (A) Pretreatment. (B) After orthodontic treatment. (C) After restorative treatment. (D) Twelve years of retention.

192 PA RT V I    Buccal TADs and Extra-Alveolar TADs

A

B

C •

Fig. 12.16  Serial panoramic radiographs. (A) Pretreatment. (B) After orthodontic treatment. (C) Twelve years of retention.

the TSAD to the target tooth eliminates the possibility of unwanted extraneous movement of other teeth. A collapsed dental occlusion is a common problem that is hard to treat for clinicians. A noted cause of the collapsed occlusion is untreated missing teeth. Patients with missing teeth tend to have altered tooth positions; typical signs can include migration of adjacent teeth into the spaces, midline deviation, loss of vertical dimension, and a multilevel occlusal plane.17 Missing teeth and the tipping of adjacent teeth lead to infraocclusion of dental components, extrusion of opposing teeth, and distortion of the occlusal planes.

Another cause of collapsed occlusion is a crossbite or a scissors-bite. Previous studies have reported that even if there was no arch-length discrepancy in the posterior segments, the mandibular second molars can erupt lingually, producing a buccal crossbite or a scissors-bite.18,19 The primary feature of posterior crossbite is that at least one tooth in the maxillary arch is ectopically positioned buccally or lingually with respect to the corresponding mandibular tooth or teeth.20 Although there have been some conventional methods presented in the literature for correction of buccal posterior crossbites in the permanent dentition, such as the modified transpalatal arch,21 and cross-arch elastics,22 most of them have some unwanted movement on the anchorage teeth. Responsive movement of anchorage teeth is unavoidable because of the principal of action and reaction in conventional orthodontic treatment when using a continuous archwire. If the conventional method is applied in a patient with collapsed occlusion, the outcome is not an ideal symmetric occlusion but a compromised occlusion, and iatrogenic asymmetry of the dental arches. Therefore problem-oriented segmental approaches are preferred to normalize a collapsed occlusion instead of a continuous archwire technique in the first treatment stage. A segment treatment strategy essentially aims to resolve the vertical and tipping problems of each segment separately. The use of limited fixed orthodontic appliances in segmental techniques also provides the design of simplified orthodontic biomechanics. This approach will reduce adjustment time significantly and improve patient satisfaction because of the increased comfort as a result of limited fixed orthodontic appliances. The development of skeletal anchorage systems has also made it possible to move specific teeth without involving other teeth. Skeletal anchorage reduces the side effects that occur with dental anchorage and simplifies the orthodontic appliances and the treatment biomechanics.23–25 Yun et al.20 reported application of the TSAD as an indirect skeletal anchorage system to correct the scissors-bite after bonding the fixed orthodontic appliances. Although this method helps minimize unwanted tooth movement, the control is limited. To correct the collapsed occlusion, the clinician will prefer more stable anchorage for the control of several teeth in the segment. The success rates of mini-implants devices varies from 75.2% to 93.6%, and the stability can be affected when heavier forces are necessary.26 Orthodontic miniplates were introduced and applied as a reliable alternative to orthodontic mini-implants.27,28 The C-tube miniplate in Case 3 provided solid skeletal anchorage to control the badly tipped segment. The C-tube miniplate can withstand heavier forces, with dependable stability. When designing the biomechanics, the C-tube miniplate also has advantage over a simple mini-implants or other rigid miniplates, since the neck and head can be manipulated when clinician needs to adjust the amount or direction of the force.29

CHAPTER 12  Managing Complex Orthodontic Tooth Movement With C-Tube Miniplates

The body can be bent or adjusted to closely adapt to the anatomic contour of the bone surface. The plate is securely away from the roots and the attached gingiva, while the long neck lets the tube portion exit the tissue through the attached gingiva. The anchoring screws that are used to stabilize the C-plate rarely interfere with roots of the adjacent teeth. It is a crucial property because the correction of collapsed occlusion requires a large tooth movement to upright and intrude the tipped teeth. Even though there is considerable orthodontic tooth movement, there is no need for repositioning the skeletal anchorage. C-tube miniplates are perfectly efficient devices to use in push-type force delivery systems to the teeth, all aiding in the correction of midline deviation and in correcting a collapsed occlusion without undesirable side effects, and therefore a shorter treatment period. This technique provided maximum treatment efficiency and reduced cost with the least amount of complex hardware. 

Conclusion The I-type C-tube miniplate provides reliable skeletal anchorage to support a substantial pushing force to translate an entire quadrant of the dentition. The biomechanical system described provided the necessary tooth movement to correct dental midline asymmetries efficiently and comfortably with a desirable outcome.

References 1. Lewis PD: The deviated midline, Am J Orthod 70:601–616, 1976. 2. Van Steenbergen E, Nanda R: Biomechanics of orthodontic correction of dental asymmetries, Am J Orthod Dentofacial Orthop 107:618–624, 1995. 3. Gianelly AA, Paul IA: A procedure for midline correction, Am J Orthod 58:264–267, 1970. 4. Beyer JW, Lindauer SJ: Evaluation of dental midline position, Semin Orthod 4:146–152, 1998. 5. Cheng HC, Cheng PC: Factors affecting smile esthetics in adults with different types of anterior overjet malocclusion, Korean J Orthod 47:31–38, 2017. 6. Kai R, Umeki D, Sekiya T, Nakamura Y: Defining the location of the dental midline is critical for oral esthetics in camouflage orthodontic treatment of facial asymmetry, Am J Orhtod Dentofacial Orthop 150:1028–1038, 2016. 7. Bishara SE, Burkey PS, Kharouf JG: Dental and facial asymmetries: a review, Angle Orthod 64:89–98, 1994. 8. Nanda R, Margolis MJ: Treatment strategies for midline discrepancies, Semin Orthod 2:84–89, 1996. 9. Tayer BH: The asymmetric extraction decision, Angle Orthod 62:291–297, 1992. 10. Rebellato J: Asymmetric extractions used in the treatment of patients with asymmetries, Semin Orthod 4:180–188, 1998. 11. Carano A, Testa M: The distal jet for upper molar distalization, J Clin Orthod 30:374–380, 1996. 12. Byloff FK, Darendeliler MA: Distal molar movement using the pendulum appliance. Part 1: clinical and radiological evaluation, Angle Orthod 67:249–260, 1997.

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13. Fuziy A, Rodrigues de Almeida R, Janson G, Angelieri F, Pinzan A: Sagittal, vertical, and transverse changes consequent to maxillary molar distalization with the pendulum appliance, Am J Orthod Dentofacial Orthop 130:502–510, 2006. 14. Sugawara J, Daimaruya T, Umemori M, et al.: Distal movement of mandibular molars in adult patients with the skeletal anchorage system, Am J Orthod Dentofacial Orthop 125:130–138, 2004. 15. Choi YJ, Lee JS, Cha JY, Park YC: Total distalization of the maxillary arch in a patient with skeletal Class II malocclusion, Am J Orthod Dentofacial Orthop 139:823–833, 2011. 16. Oh YH, Park HS, Kwon TG: Treatment effects of microimplant aided sliding mechanics on distal retraction of posterior teeth, Am J Orthod Dentofacial Orthop 139:470–481, 2011. 17. Chung KR, Kim SH: Correction of collapsed occlusion with degenerative joint disease focused on the mandibular arch and timely relocation of a miniplate, Am J Orthod Dentofacial Orthop 141:e53–e63, 2012. 18. Tollaro I, Defraia E, Marinelli A, Alarashi M: Tooth abrasion in unilateral posterior crossbite in the deciduous dentition, Angle Orthod 72:426–430, 2002. 19. Pinto AS, Buschang PH, Throckmorton GS, Chen P: Morphological and positional asymmetries of young children with functional unilateral posterior crossbite, Am J Orthod Dentofacial Orthop 120:513–520, 2001. 20. Yun SW, Lim WH, Chong DR, Chun YS: Scissors-bite correction on second molar with a dragon helix appliance, Am J Orthod Dentofacial Orthop 132:842–847, 2007. 21. Gerhard K, Weiland FJ: Goal-oriented positioning of maxillary second molars using the palatal intrusion technique, Am J Orthod Dentofacial Orthop 110:466–468, 1996. 22. Menezes LM, Ritter DE, Locks A: Combining traditional technique to correct anterior open bite and posterior crossbite, Am J Orthod Dentofacial Orthop 143:412–420, 2013. 23. Moon CH, Lee JS, Lee HS, Choi JH: Non-surgical treatment and retention of open bite in adult patients with orthodontic mini-implants, Korean J Orthod 39:402–419, 2009. 24. Kim MJ, Park SH, Kim HS, Mo SS, Sung SJ, Jang GW, et al.: Effects of orthodontic mini-implant position in the dragon helix appliance on tooth displacement and stress distribution: a threedimensional finite element analysis, Korean J Orthod 41:191–199, 2011. 25. Lee KJ, Park YC, Hwang WS, Seong EH: Uprighting mandibular second molars with direct miniscrew anchorage, J Clin Orthod. 41:627–635, 2007. 26. Lee JH: Replacing a failed mini-implant with a miniplate to prevent interruption during orthodontic treatment, Am J Orthod Dentofacial Orthop 139:849–857, 2011. 27. Chen CH, Hsieh CH, Tseng YC, Huang IY, Shen YS, Chen CM: The use of mini-plate osteosynthesis for skeletal anchorage, Plast Reconstr Surg 120:232–237, 2007. 28. Sugawara J, Kanzaki R, Takahashi I, Nagasaka H, Nanda R: Distal movement of maxillary molars in nongrowing patients with the skeletal anchorage system, Am J Orthod Dentofacial Orthop 129:723–733, 2006. 29. Ahn HW, Chung KR, Kang SM, Lin L, Nelson G, Kim SH: Correction of dental Class III with posterior open bite by simple biomechanics using an anterior C-tube miniplate, Korean J Orthod 42:270–278, 2012.

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13

Application of Buccal TADs for Distalization of Teeth TORU DEGUCHI, KEIICHIRO WATANABE

Temporary anchorage devices (TADs) have been widely used as one of the most sufficient anchorage devices in orthodontic field in the last decade. TADs could be used to control anchorage in all anteroposterior (A-P), vertical, and transverse dimensions. In this chapter we would like to provide some information with regard to the effectiveness of TADs in controlling the anchorage in A-P dimension during distalization of entire arch in nonextraction cases.

Methods of Distalizing Molars Distalizing molars is one of the required tooth movement in correction of Class II or III molar relationship, and gaining space to eliminate crowding. Especially, when the case is treated with nonextraction with crowding, distalization of molars is critical. Conventional methods to distalize molars are using plate type appliances,1 spring incorporated appliances,2,3 distal jet,4 intermaxillary elastics, and sliding jigs.5,6 However, if the second molars are present and already erupted, it is extremely difficult to achieve enough distalization of the molars. Many Class II mechanics require patient cooperation and result in reciprocal force to other teeth, resulting in unwanted tooth movement. 

Distalizing Molars by TADs Recently, the use of dental implant,7 mini-implants,8 and miniplates9 as orthodontic anchorages has been proven to be effective in clinical orthodontics. Since there is no loss of anchorage without patient cooperation with the use of miniimplants and miniplates these have been used in correction of Class II or III and distalizing the entire arch. Several types of temporary anchorage devices (TADs), such as buccal mini-implants,10 palatal mini-implants,11 and miniplates,12 have been introduced to distalize the teeth. Advantage of buccal TADs compared to palatal TADs is that they do not require additional complex laboratory work or appliance and are easy to place. According to the location where the palatal TADs are placed, you should be careful to avoid damaging nerve, blood vessel, and sinus perforation. Miniplates are

also useful and might resist more orthodontic force, particularly, in the mandible distalization. However, miniplates require more extensive surgery than buccal TADs and result in higher cause of inflammation. On the other hand, disadvantage of buccal TADs is possible root damage or root proximity that results in less stability.13–15 Especially during distalizing the arch, since buccal TADs are frequently placed at the premolar or molar area, neighboring teeth sometimes would be close to the TADs. Thus ideally, buccal TADs should be as small as possible to avoid root damage and proximity during treatment.16 

Biomechanics in Distalizing Molars With Buccal TADs Biomechanical consideration would be less complicated compared to conventional biomechanics without using TADs. The most ideal suggested location for TADs is between the second premolar and the first molar,17 attaching a retraction hook distal or mesial of the canine and using a power chain or closed coil from the TADs to the hook (Fig. 13.1A). However, in some cases according to various factors, such as the morphology of the root, type of alveolar bone (quality and quantity), difference in the occlusal force, etc., additional mechanics are required to efficiently distalize the entire arch with en masse movement. One simple way is to add an open coil between the molars and first distalize the second molar and continue the distalization of the other teeth (see Fig. 13.1A). We also use the Tweed mechanics18 to distalize the second molar by helical bulbous loop, with open coil between the molars, and counteract the reciprocal force by using TADs instead of J-hook head gear (Fig. 13.1B). In addition, crimpable stop is required distal of the first or the second premolar to keep the loop active (see Fig. 13.1B). If the patient is cooperative, you could add the Class II elastic to reinforce the anchorage. One of the problems in distalizing molars is the extrusion from the topping movement. With having TADs, vertical control is also possible by ligating the TADs to the 195

196 PA RT V I     Buccal TADs and Extra-Alveolar TADs

A

B

C

• Fig. 13.1  Schema of various methods in distalizing the arch. Distalization by direct anchorage from the

TADs and with the assist from the open coil (A). Distalization similar to Tweed mechanics (B). Distalization with retracting canine and incisors with loops and with addition of the vertical control in the incisors (C).

molar, while distalizing molars (or premolars according to the teeth that need to be controlled) (see Fig. 13.1B). If sliding mechanics rather than en masse retraction are required, a retraction force could be directly applied to the canine with a closing loop activated by the TADs and simultaneously retract the canine and the anteriors (see Fig. 13.1C). In addition, placing TADs in the anterior results in better control during the incisor retraction. Factors that should be considered during distalization (also anterior retraction) are the position of the TADs, the location, and the length of the retraction hook. During the distalization by TADs, generally, alignment and leveling have been already accomplished, and require bodily movement of the anterior teeth, without extrusion of the posterior teeth. This bodily movement of the entire arch, without extrusion, is achieved only when the retraction force from the TADs to the hook passes near or above the center of the resistance (CR).19,20 Since the CR for six anterior teeth is known to locate near distal of the canine and about 7 mm above the alveolar bone,21 it is almost impossible to apply the force above the CR. To apply the retraction force as close as possible to the CR, TADs must be placed further above, near the border of attached and removal gingiva.19 However, in most cases, there is limited area of attached gingiva, which makes it difficult to place the TADs near CR. Retraction hooks also need to be as long as possible for the retraction force to be near the CR.19,20 

Treatment Outcome of Distalization by TADs There have been several studies that have compared the treatment outcomes of the conventional and TAD methods in the past.22–24 Treatment outcome in distalization in Class II cases have also been reported.10 With the use of TADs,

distalization of approximately 2.8 mm to 4.8 degrees of tipping with 0.6 mm of intrusion was observed. This indicates that Class II end-on molars would be corrected into Class I molar relationship by simple distalization of molars (these cases were only distalized, without any additional appliances). By incorporating the “Tweed” mechanics, we believe that more distalization, of up to 5.0 mm, is possible so that full Class II will be corrected into Class I molar relationship. Recently, palatal TADs have become of major interest among the TAD users in the field of orthodontics.25 Palatal TADs could also be an effective way to distalize molars, since large lingual roots of the molars could be easily moved. Past studies indicate that 4.0 mm of distalization of the molars are possible with the use of palatal TADs.26 However, as mentioned earlier, palatal TADs require complicated design and device. Miniplates have also been known to effectively distalize the molars.27 Average of 4.0 mm of distalization of molars, without any side effect, was reported; however, it requires mucoperiosteal incision and flap during placement and removal, and considerable pain and discomfort during the procedure, with higher medical cost. For patients, we believe that ideal orthodontic treatment should provide a sufficient treatment effect with the use of a simple and straightforward device. 

Stability of Distalization by TADs There have been only few studies that reported the stability of cases treated by using TADs.23,28 Most of the studies have shown that there is no statistically significant difference in the stability between the conventional method and cases treated with TADs. However, since the amount of tooth movement is significantly more than the conventional method in distalization, there may be a tendency for the TAD-treated cases to be less stable. In the case of openbite, there was a marginal

CHAPTER 13  Application of Buccal TADs for Distalization of Teeth

197

B

CASE 1 Pre treatment Age: 12 yrs 10 mo

C

A •

Fig. 13.2  Pretreatment facial and intraoral photographs (A), and panoramic (B) and cephalometric (C) radiographs in Case 1.

tendency for the TAD-treated case to relapse more than the conventional method.23 In addition, there was a difference in the pattern of the relapse, namely that TAD-treated openbite cases had a tendency for the mandibular molar to extrude, which resulted in significant relapse. From our recent study that evaluated the stability of the distalization of molars, after 2 to 3 years of retention, there was approximately 0.8 mm (20%) of relapse in anterior-posterior direction, 0.5 mm (49%) in vertical direction, and 0.6 degrees (118%) of tipping relapse. In the case of distalization, the amount of retromolar area is another important factor for the stability. We found out that less than 18 mm of retromolar area in pretreatment or less than 15 mm in posttreatment resulted in significant relapse of the molars (unpublished data). 

Case 1. Distalization of Maxillary Molars in Skeletal II, Angle Class II Case Diagnosis A 12-year 10-month-old female had a chief complaint of protruded upper teeth. She had a convex profile, with lip incompetent and strain at the mentalis (Fig. 13.2A). From the intraoral photo, her angle classification was Class II molar and canine relationship with increased overjet and overbite. There was also deep curve of spee in the mandible and a spaced maxillary arch. Panoramic radiograph showed all permanent teeth (Fig. 13.2B). Cephalometric analysis resulted in Skeletal 2 with ANB (Point A-Nasion-Point B) of 10 degrees, short mandible, and increased axial inclination of mandibular incisors (Fig. 13.2C; Table 13.1). 

Treatment Plan Nonextraction with 0.022 slot edgewise bracket was planned with the use of TADs between the maxillary second premolar and the first molar for the absolute anchorage. We planned to distalize approximately 3.0 mm of posterior molars with TADs. Increased overjet and overbite were planned to be corrected by flattening the curve of spee and intrusion of the maxillary incisors.

Treatment Progress After 6 months in treatment, leveling and alignment was mostly achieved, and TADs were placed between the second premolar and first molar. Immediate loading with 50 rm of force was performed to distalize the molars (Fig. 13.3A). During the distalization, the right TAD became loose, and was replaced between the molars (Fig. 13.3B). After 13 months of treatment, molar relationship was almost Class I; however, we continued to distalize to correct the Class II canine (Fig. 13.3C). After removal of the edgewise appliance, a wrap-around retainer was delivered in both maxilla and in the mandible. Total active orthodontic treatment time was 19 months. 

Treatment Results On the posttreatment facial photos (Fig. 13.4A), improvement of profile was observed but slight convexity remained. Strain in mentalis and lip incompetent were improved. Improvement of occlusion with Class I molar and canine relationship and ideal overjet and overbite were achieved from the intraoral photos. However, there was slightly less intercuspation at the right canine area.

198 PA RT V I     Buccal TADs and Extra-Alveolar TADs

TABLE   Cephalometric Analysis of Case 1 13.1 

Norm

S. D.

Pretreatment

Posttreatment

After 2 yrs Retention

SNA (degrees)

82.0

3.5

86.1

83.1

83.6

SNB (degrees)

80.9

3.4

75.7

74.5

75.0

SN - MP (degrees)

32.9

5.2

33.8

35.1

34.4

FMA (MP-FH) (degrees)

23.9

4.5

29.6

31.8

30.4

ANB (degrees)

1.6

1.5

10.4

8.6

8.6

U1 - NA (mm)

4.3

2.7

2.5

–0.8

–1.0

U1 - SN (degrees)

102.8

5.5

102.6

93.2

95.4

L1 - NB (mm)

4.0

1.8

9.9

9.4

8.8

L1 - MP (degrees)

95.0

7.0

103.0

107.3

105.0

Overbite (mm)

2.5

2.0

6.0

1.2

1.6

Overjet (mm)

2.5

2.5

6.5

1.6

2.1

Lower Lip to E-Plane (mm)

−2.0

2.0

4.1

2.9

3.6

Upper Lip to E-Plane (mm)

−6.0

2.0

2.1

0.7

0.2

Measurement Hard Tissue

Soft Tissue

ANB, Point A-Nasion-Point B; FMA, Frankfort mandibular plane angle; SNA, Sella-Nasion-Point A; SNB, Sella-Nasion-Point B.

A

B

C • Fig. 13.3  Progress intraoral photographs. Six months after the initiation of the orthodontic treatment (A). Maxillary right TAD was replaced from mesial of the first molar to mesial of the second molar (arrow in B). Thirteen months after the initiation of the orthodontic treatment (C).

CHAPTER 13  Application of Buccal TADs for Distalization of Teeth

199

B

CASE 1 Post treatment Age:14 yrs 09 mo

A

C • Fig. 13.4  Posttreatment facial and intraoral photographs (A), and panoramic (B) and cephalometric (C) radiographs in Case 1.

CASE 1 after 2 yrs retention Age: 16 yrs 09 mo

A

B • Fig. 13.5  Postretention (2 years) treatment facial and intraoral photographs (A), and cephalometric (B) radiograph in Case 1.

From the panoramic radiograph (Fig. 13.4B), proper root parallelism is shown. Cephalometric analysis resulted in decreased ANB, but increased axial inclination of mandibular incisors and an increase in the mandibular plane angle were observed (Fig. 13.4C; see Table 13.1). 

Retention After 2 years in retention, settling of the occlusion was observed that resulted in improvement of right canine occlusion (Fig. 13.5A). Also there was a significant improvement

in her profile. Cephalometric analysis resulted in decreased axial inclination of the mandibular incisors that resulted in slight increase of overjet (Fig. 13.5B; see Table 13.1). Soft tissue analysis, such as upper lip to S-line, lower lip to E-line, and nasolabial angle also improved during the retention phase. 

Superimposition Overall superimposition showed a clockwise rotation of the mandible and some improvement in the profile (Fig. 13.6A).

200 PA RT V I     Buccal TADs and Extra-Alveolar TADs

B

A

C

• Fig. 13.6  Superimposition of the overall (A), maxilla (B), and mandible (C) of pretreatment (black), posttreatment (red), and 2 years postretention (blue) in Case 1.

B

CASE 2 Pre treatment Age: 21 yrs 08 mo

C

A •

Fig. 13.7  Pretreatment facial and intraoral photographs (A), and panoramic (B) and cephalometric (C) radiographs in Case 2.

Reginal tracing showed in the maxilla, approximately 2.5 mm of distalization of molars with no vertical change and approximately 7 degrees of retraction and 2.0 mm of intrusion was observed (Fig. 13.6B). In the mandible, approximately 3.0 mm of mesial movement and slight extrusion (that resulted in clockwise rotation of the mandible), as well as some labial flaring and 3.0 mm of intrusion of incisors, were observed (Fig. 13.6C). 

Case 2: Distalization of Mandibular Molars in Skeletal III, Angle Class III Case Diagnosis A male patient of 21 years and 8 months had chief complaint of anterior crossbite. He had a concave profile, with increased anterior facial height, with slight asymmetry of the mandible (Fig. 13.7A). Intraoral photograph showed

CHAPTER 13  Application of Buccal TADs for Distalization of Teeth

201

TABLE   Cephalometric Analysis of Case 2 13.2 

Norm

S. D.

Pretreatment

Posttreatment

After 2 yrs Retention

SNA (degrees)

82.0

3.5

84.9

85.1

84.7

SNB (degrees)

80.9

3.4

85.9

86.2

86.0

SN - MP (degrees)

32.9

5.2

35.0

34.7

33.9

FMA (MP-FH) (degrees)

26.9

4.5

28.1

28.0

27.5

ANB (degrees)

1.6

1.5

−1.0

−1.1

−1.3

U1 - NA (mm)

4.3

2.7

6.6

9.3

8.4

U1 - SN (degrees)

102.1

5.5

115.9

120.2

120.5

L1 - NB (mm)

4.0

1.8

7.2

4.9

4.5

L1 - MP (degrees)

95.0

7.0

78.9

76.8

75.1

Overbite (mm)

2.3

2.0

0.1

1.8

1.1

Overjet (mm)

3.2

2.5

–2.4

2.9

2.0

Lower Lip to E-Plane (mm)

2.0

2.0

4.6

1.7

1.2

Upper Lip to E-Plane (mm)

−1.0

2.0

0.2

−0.7

0.1

Measurement Hard Tissue

Soft Tissue

ANB, Point A-Nasion-Point B; FMA, Frankfort mandibular plane angle; SNA, Sella-Nasion-Point A; SNB, Sella-Nasion-Point B.

Class III molar and right canine and Class I canine relationship on the left (full Class III molar) with anterior crossbite. The mandible was shifted 2.5 mm to the left. He had oral hygiene problem, which was addressed at the beginning of the orthodontic treatment. From panoramic radiograph (Fig. 13.7B), mandibular left third molar was missing. Cephalometric analysis resulted in Skeletal III with ANB of −1.0 degrees, increased anterior facial height, increased axial inclination of maxillary incisors, and protruded mandibular incisors (Fig. 13.7C; Table 13.2). 

we started to retract the mandibular by closed coil from the TADs to the hook attached to the distal of the canine (Fig. 13.8B). We used a long hook so that the retraction force would be close to the CR. After 21 months, we replaced the TAD on the right side, since we needed further retraction (Fig. 13.8C). After removal of the edgewise appliance, a wraparound retainer was delivered in both maxilla and in the mandible, and also bonded retainer was used in the mandible. Total active orthodontic treatment time was 33 months. 

Treatment Plan

On the posttreatment facial photos (Fig. 13.9A), improvement of anterior facial height and lower lip was observed but still had a concave profile. From the intraoral photographs, Class I canine was achieved, but the molar was finished in Class III (super-Class I) relationship. Crossbite was corrected and ideal overjet and overbite were achieved. However, because of patient’s poor oral hygiene maintenance, white spots in the incisors and gingival recession were observed in canine and premolar region. From the panoramic radiograph (Fig. 13.9B), proper root paralleling was achieved, but some external root resorption was observed at the maxillary incisors. Cephalometric analysis resulted in a slight decrease in ANB by the late growth of the mandible and increased axial inclination of maxillary incisors (Fig. 13.9C; see Table 13.2). 

Nonextraction with 0.018 slot edgewise bracket was planned with the use of TADs, between the mandibular second premolar and the first molar for the absolute anchorage. Class I molar and canine and ideal overjet and overbite were planned to be corrected by retracting the entire mandibular arch.

Treatment Progress Before initiating active treatment, mandibular right third molar was extracted. After 3 months in treatment, TADs were placed between the mandibular second premolar and first molar. We first ligated the canine and the TADs to lace back until leveling and alignment of the mandibular arch were achieved. (Fig. 13.8A). After 10 months of leveling,

Treatment Results

202 PA RT V I     Buccal TADs and Extra-Alveolar TADs

• Fig. 13.8  Progress

intraoral photographs. Three (A), 10 (B), and 21 (C) months after the initiation of the orthodontic treatment. After 10 months, TAD on the right side was replaced for further retraction (arrow in B).

B

CASE 2 Post treatment Age: 23 yrs 05 mo

C

A

• Fig. 13.9  Posttreatment facial and intraoral photographs (A), and panoramic (B) and cephalometric (C) radiographs in Case 2.

Retention

Superimposition

After 2 years in retention (Fig. 13.10A), there was no significant change in his profile. Oral photographs showed stable occlusion, but a slightly decreased overjet was observed at the right maxillary lateral incisor. There was also no significant change from the panoramic radiograph (Fig. 13.10B) and cephalometric analysis (Fig. 13.10C; see Table 13.2). 

Overall superimposition (Fig. 13.11A) showed a 2.0 to 3.0 mm of horizontal growth of the mandible. Maxillary superimposition resulted in 1.5 to 2.0 mm of mesial movement and some buccal flaring of the incisors (Fig. 13.11B). Mandibular tracing resulted in 2.0 to 3.0 mm distal movement and tip back of molars without any extrusion, and bodily incisors retraction of 3.0 mm was observed (Fig. 13.11C). 

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203

B

CASE 2 AFTER 2 Yrs retention Age:25 yrs 05 m0

A

C • Fig. 13.10  Postretention (2 years) treatment facial and intraoral photographs (A), and panoramic (B) and cephalometric (C) radiograph in Case 2.

B

A

C

• Fig. 13.11  Superimposition of the overall (A), maxilla (B), and mandible (C) of pretreatment (black), posttreatment (red), and 2 years postretention (blue) in Case 2.

Case 3: Distalization of Maxillary and Mandibular Molars in Skeletal II, Angle Class II Bimaxillary Case Diagnosis A female patient of 21 years and 7 months had chief complaint of protrusion and crowding. She had a convex profile (Fig. 13.12A). Intraoral photograph showed Class I molar

and canine relationship with scissors-bite on maxillary and mandibular left second molar. Panoramic radiograph (Fig. 13.12B) showed short root on the mandibular incisors, and the maxillary right central had history of trauma with root canal treatment. Cephalometric analysis resulted in Skeletal II with ANB of 4.2 degrees, increased mandibular plane angle, and increased axial inclination of mandibular incisors (Fig. 13.12C; Table 13.3). 

204 PA RT V I     Buccal TADs and Extra-Alveolar TADs

B

CASE 3 Pre treatment Age: 21yrs 7 mo

A

C • Fig. 13.12  Pretreatment facial and intraoral photographs (A), and panoramic (B) and cephalometric (C) radiographs in Case 3.

TABLE   Cephalometric Analysis of Case 3 13.3 

Measurement

Norm

S. D.

Pretreatment

Posttreatment

After 3 yrs Retention

SNA (degrees)

82.0

3.5

78.2

78.0

77.5

SNB (degrees)

80.9

3.4

74.0

73.7

73.5

SN - MP (degrees)

32.9

5.2

45.1

41.4

38.0

FMA (MP-FH) (degrees)

27.9

4.5

36.5

37.4

34.8

ANB (degrees)

1.6

1.5

4.2

4.3

4.0

U1 - NA (mm)

4.3

2.7

9.1

4.6

5.8

U1 - SN (degrees)

101.8

5.5

110.5

98.5

99.3

L1 - NB (mm)

4.0

1.8

12.5

9.4

10.4

L1 - MP (degrees)

95.0

7.0

102.3

100.4

101.6

Overbite (mm)

2.3

2.0

0.5

1.5

1.7

Overjet (mm)

3.2

2.5

3.9

1.8

2.2

Lower Lip to E-Plane (mm)

−2.0

2.0

4.0

2.6

2.5

Upper Lip to E-Plane (mm)

−1.8

2.5

0.5

−1.5

−2.5

Hard Tissue

Soft Tissue

ANB, Point A-Nasion-Point B; FMA, Frankfort mandibular plane angle; SNA, Sella-Nasion-Point A; SNB, Sella-Nasion-Point B.

CHAPTER 13  Application of Buccal TADs for Distalization of Teeth

205

A

B • Fig. 13.13  Progress intraoral photographs. Two (A) and 5 (C) months after the initiation of the orthodontic treatment.

B

CASE 3 Posttreatment Age:24 yrs 4 mo

A

C • Fig. 13.14  Posttreatment facial and intraoral photographs (A), and panoramic (B) and cephalometric (C) radiographs in Case 3.

Treatment Plan Extraction of maxillary right third molar, left second molar, and mandibular right and left third molar was decided, and 0.018 slot edgewise bracket was planned with the use of TADs, between the mandibular second premolar and the first molar, and between maxillary first and second molar, for the absolute anchorage. Class I molar and canine and ideal overjet and overbite were planned to be corrected by retracting both maxillary and mandibular arch. 

Treatment Progress After 2 months in treatment, TADs were placed between the mandibular second premolar and first molar. We first ligated the mandibular left first molar, to prevent lingual

tipping during aligning the mandibular left second molar (Fig. 13.13A). Five month later, TADs were placed between maxillary first and second molar and started retracting the entire arch (Fig. 13.13B). After removal of the edgewise appliance, a wraparound retainer was delivered for the maxilla, and bonded retainer was used in the mandible. Total active orthodontic treatment time was 33 months. 

Treatment Results On the posttreatment facial photos (Fig. 13.14A), straight profile was achieved. From the intraoral photographs, Class I canine and molar relationship was achieved. Scissors-bite was corrected and ideal overjet and overbite were achieved. From the panoramic radiograph (Fig. 13.14B), proper root paralleling was achieved, but some external root

206 PA RT V I     Buccal TADs and Extra-Alveolar TADs

resorption was observed at the maxillary incisors. Cephalometric analysis resulted in a slight increase in ANB by clockwise rotation of the mandible, and decreased axial inclination of maxillary and mandibular incisors was observed (Fig. 13.14C; see Table 13.3). 

showed stable occlusion, without any significant change. There was also no significant change from the panoramic (Fig. 13.15B) or cephalometric analysis (Fig. 13.15C; see Table 13.3). 

Superimposition

Retention After 3 years in retention (Fig. 13.15A), there was no significant change in the client's profile. Intraoral photographs

Overall superimposition (Fig. 13.16A) showed a clockwise rotation of the mandible, and retraction of the upper and lower lips was observed. Maxillary superimposition resulted

B

CASE 3 After 3 yrs retention Age: 27 yrs 4 mo

A

C • Fig. 13.15  Postretention (3 years) treatment facial and intraoral photographs (A), and panoramic (B) and cephalometric (C) radiograph in Case 3.

B

A

C • Fig. 13.16  Superimposition of the overall (A), maxilla (B), and mandible (C) of pretreatment (black), posttreatment (red), and 3 years postretention (blue) in Case 3.

CHAPTER 13  Application of Buccal TADs for Distalization of Teeth

in approximately 4.5 mm of distalization of molars, and 5.0 mm retraction of the incisors (Fig. 13.16B). Mandibular tracing resulted in approximately 3.0 mm of distalization and tip back of molars, and 3.0 mm of incisor retraction was observed (Fig. 13.16C).

Acknowledgement We thank Dr. Hiroshi Kamioka of Okayama University and Dr. Eiji Tanaka of Tokushima University for the advice and assistance. The authors dedicate this chapter to celebrate of the life of Dr. Shingo Kuroda—excellent clinician, scholar, and friend.

References 1. Hilgers JJ: The pendulum appliance for Class II non-compliance therapy, J Clin Orthod 26(11):706–714, 1992. 2. Locatelli R, Bednar J, Dietz VS, Gianelly AA: Molar distalization with superelastic NiTi wire, J Clin Orthod 26(5):277–279, 1992. 3. Erverdi N, Koyutürk O, Küçükkeles N: Nickel-titanium coil springs and repelling magnets: a comparison of two different intra-oral molar distalization techniques, Br J Orthod 24(1):47– 53, 1997. 4. Carano A, Testa M: The distal jet for upper molar distalization, J Clin Orthod 30(7):374–380, 1996. 5. Jones RD, White JM: Rapid Class II molar correction with an open-coil jig, J Clin Orthod 26(10):661–664, 1992. 6. Haydar S, Uner O: Comparison of Jones jig molar distalization appliance with extraoral traction, Am J Orthod Dentofacial Orthop 117(1):49–53, 2000. 7. Roberts WE, Helm FR, Marshall KJ, Gongloff RK: Rigid endosseous implants for orthodontic and orthopedic anchorage, Angle Orthod 59(4):247–256, 1989. 8. Kanomi R: Mini-implant for orthodontic anchorage, J Clin Orthod 31(11):763–767, 1997. 9. Umemori M, Sugawara J, Mitani H, Nagasaka H, Kawamura H: Skeletal anchorage system for open-bite correction, Am J Orthod Dentofacial Orthop 115(2):166–174, 1999. 10. Yamada K, Kuroda S, Deguchi T, Takano-Yamamoto T, Yamashiro T: Distal movement of maxillary molars using miniscrew anchorage in the buccal interradicular region, Angle Orthod 79(1):78–84, 2009. 11. Wehrbein H, Merz BR, Diedrich P, Glatzmaier J: The use of palatal implants for orthodontic anchorage. Design and clinical application of the orthosystem, Clin Oral Implants Res 7(4):410– 416, 1996. 12. Sugawara Y, Kuroda S, Tamamura N, Takano-Yamamoto T: Adult patient with mandibular protrusion and unstable occlusion treated with titanium screw anchorage, Am J Orthod Dentofacial Orthop 133(1):102–111, 2008. 13. Kuroda S, Sugawara Y, Deguchi T, Kyung HM, TakanoYamamoto T: Clinical use of miniscrew implants as orthodontic anchorage: success rates and postoperative discomfort, Am J Orthod Dentofacial Orthop 131(1):9–15, 2007. 14. Kuroda S, Yamada K, Deguchi T, Hashimoto T, Kyung HM, Takano-Yamamoto T: Root proximity is a major factor for screw failure in orthodontic anchorage, Am J Orthod Dentofacial Orthop 131(4 Suppl l):S68–S73, 2007.

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15. Watanabe H, Deguchi T, Hasegawa M, Ito M, Kim S, TakanoYamamoto T: Orthodontic miniscrew failure rate and root proximity, insertion angle, bone contact length, and bone density, Orthod Craniofac Res 16(1):44–55, 2013. 16. Suzuki M, Deguchi T, Watanabe H, et al.: Evaluation of optimal length and insertion torque for miniscrews, Am J Orthod Dentofacial Orthop 144(2):251–259, 2013. 17. Deguchi T, Nasu M, Murakami K, Yabuuchi T, Kamioka H, Takano-Yamamoto T: Quantitative evaluation of cortical bone thickness with computed tomographic scanning for orthodontic implants, Am J Orthod Dentofacial Orthop 129(6). 721, 2006. e7–e12. 18. Chae JM: A new protocol of Tweed-Merrifield directional force technology with microimplant anchorage, Am J Orthod Dentofacial Orthop 130(1):100–109, 2006. 19. Lee KJ, Park YC, Hwang CJ, et  al.: Displacement pattern of the maxillary arch depending on miniscrew position in sliding mechanics, Am J Orthod Dentofacial Orthop 140(2):224–232, 2011. 20. Kojima Y, Kawamura J, Fukui H: Finite element analysis of the effect of force directions on tooth movement in extraction space closure with miniscrew sliding mechanics, Am J Orthod Dentofacial Orthop 142(4):501–508, 2012. 21. Vanden Bulcke M, Sachdeva R, Burstone CJ: The center of resistance of anterior teeth during intrusion using the laser reflection technique and holographic interferometry, Am J Orthod 90(3):211–219, 1986. 22. Deguchi T, Murakami T, Kuroda S, Yabuuchi T, Kamioka H, Takano-Yamamoto T: Comparison of the intrusion effects on the maxillary incisors between implant anchorage and J-hook headgear, Am J Orthod Dentofacial Orthop 133(5):654–660, 2008. 23. Deguchi T, Kurosaka H, Oikawa H, et al.: Comparison of orthodontic treatment outcomes in adults with skeletal open bite between conventional edgewise treatment and implant-anchored orthodontics, Am J Orthod Dentofacial Orthop 139(4 Suppl l):S60–S68, 2011. 24. Kuroda S, Yamada K, Deguchi T, Kyung HM, Takano-Yamamoto T: Class II malocclusion treated with miniscrew anchorage: comparison with traditional orthodontic mechanics outcomes, Am J Orthod Dentofacial Orthop 135(3):302–309, 2009. 25. Lee SK, Abbas NH, Bayome M, et al.: A comparison of treatment effects of total arch distalization using modified C-palatal plate vs buccal miniscrews, Angle Orthod 88(1):45–51, 2018. 26. Gelgör IE, Büyükyilmaz T, Karaman AI, Dolanmaz D, Kalayci A: Intraosseous screw-supported upper molar distalization, Angle Orthod 74(6):838–850, 2004. 27. Sugawara J, Kanzaki R, Takahashi I, Nagasaka H, Nanda R: Distal movement of maxillary molars in nongrowing patients with the skeletal anchorage system, Am J Orthod Dentofacial Orthop 129(6):723–733, 2006. 28. Marzouk ES, Kassem HE: Long-term stability of soft tissue changes in anterior open bite adults treated with zygomatic miniplate-anchored maxillary posterior intrusion, Angle Orthod 88(2):163–170, 2018.

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14

Application of Extra-Alveolar Mini-Implants to Manage Various Complex Tooth Movements MARCIO RODRIGUES DE ALMEIDA

Introduction Mini-implants or mini-implants are absolute anchorage systems that are highly useful in orthodontic clinics. Although they are frequently fixed at sites in the alveolar process, between the roots of contiguous teeth, new extra-alveolar (E-A) sites have been suggested by Chang,1 Park,2 Almeida,3 and others. These authors recommended sites in the infrazygomatic crest (IZC) and the buccal shelf (BS) regions for many orthodontic therapies that require an efficient and secure anchorage system (Fig. 14.1). Anatomically, the IZC, or infrazygomatic crest, is a reinforced bone area, with greater thickening of the cortical layer, which extends along the maxilla from the zygoma

A

towards the molars. It is a palpable bony protuberance that is located anteriorly to the maxillary tuberosity. Several authors4–7 recognize that the IZC is an appropriate site for mini-implant placement and can be used to provide anchorage in cases of canine retraction, and en masse retraction of the anterior teeth (of the whole upper dentoalveolar process), and intrusion of the posterior teeth, as we will see later (Fig. 14.2). The buccal shelf region corresponds to the bone plateau that lies between the buccal face of the lower molars and the mandibular external oblique line. This plateau widens, as it approaches the second and third molar. According to Chang et al.8 and Almeida,9 the ideal area for the positioning of a mini-implant is between the first and second lower molars

B

• Fig. 14.1  (A and B) Extra-alveolar sites, such as infrazygomatic crest and buccal shelf, are nowadays very

common areas for absolute anchorage, to provide whole maxilla and mandibular dentoalveolar retraction.

209

210 PA RT V I     Buccal TADs and Extra-Alveolar TADs

because of the thickness of the cortical bone and the reasonable amount of attached gingiva (which decreases toward the distal teeth). These considerations are valid for the placement of mini-implants both at an angle and perpendicularly to the bone, that is, almost parallel to the long axis of the molars (Fig. 14.3). 

•

Fig. 14.2 Anatomic localization of an infrazygomatic crest (IZC) area: upper arrow showing zygomatic process, middle arrow showing the medial part of IZC, and lower arrow showing the inferior portion of the IZC.

• Fig. 14.3  Buccal shelf area (red area), with the ideal site for the positioning of a mini-implant between the first and second lower molars.

A

Indications Unlike intraalveolar mini-implants, E-A mini-implants placed in the infrazygomatic and BS regions have a precise indication, as described later. E-A screws are widely used in en masse distalization of the teeth of the upper and lower arches. This is because they allow greater anchorage, immediately after placement (primary stability), when introduced into maxillary and mandibular reinforced bone areas. IZC mini-implants are recommended in cases of enmasse anterior teeth retraction, en masse retraction of the dentoalveolar arch of the maxilla, intrusion of the posterior teeth, individual canine, premolar and molar retraction in patients with biprotrusion, distalization of canines and premolars to obtain anterior space (Fig. 14.4), and in case of patients requiring correction of the midline with en masse distalization of the teeth (Fig. 14.5). Other indications for the use of mini-implants in IZC are: anchorage for retraction of an anterior dental block in cases of superior extraction, correction of asymmetries of the occlusal plane, anchorage for the use of a cantilever in traction of impacted canines, early treatment of Class III, and for Class III orthognathic surgical planning. The indications for the use of mini-implants placed in the BS region are similar to those for mini-implants in IZC; that is, they can be used in Class III conservative treatment (camouflage), as well as for retraction and/or distalization of molars, in treatment of cases with excessive crowding of the lower teeth, mesialization of molars, anchorage for retraction of the anterior block, in cases of inferior extraction, intrusion of posterior teeth, corrections of asymmetries of the occlusal plane, deviations from the midline, anchorage for the use of a cantilever in traction of impacted lower canines, and in preparation for orthognathic surgery. Cases of bimaxillary protrusion can be treated using miniimplants placed in the BS and IZC, as seen in Fig. 14.6. A comprehensive study on the subject was conducted by the author9 in his book Extra-Alveolar mini-implants in Orthodontics. This book emphasizes the biomechanical

B • Fig. 14.4  (A and B) Individual canine retraction with infrazygomatic crest screw to provide room for the anterior teeth in patient treated without extractions.

CHAPTER 14  Application of Extra-Alveolar Mini-Implants to Manage Various Complex Tooth Movements

principles and clinical applications of this recent and effective method of anchorage. 

most important characteristics of temporary anchorage devices. It depends on various factors, such as the morphology of the mini-implants, number of threads, length, shape of the active thread, diameter, thickness, and density of the cortical bone, as well as the placement technique. Lemieux et al.11 reported that mini-implants with longer lengths allow excellent anchorage. However, they are associated with an increased risk of damage to neighboring structures, especially maxillary sinus perforation. The depth of fit and bone density at the mini-implants placement site are the best predictors of primary stability. Chen et al.12 state that using an 8-mm instead of a 6-mm mini-implants increases the success rate from 72% to 90%. Other authors also reported a higher success rate with the use of longer mini-implants. The resistance to torsional fracture of the miniimplants is directly related to their diameter, as already mentioned; that is, the larger the diameter, the greater the fracture torque. Thus it seems to be advantageous to use mini-implants with a larger diameter and longer length, such as the steel mini-implants described by Chang,7 in E-A sites.

Characteristics of Mini-Implants The mini-implants placed in the IZC and BS regions are made of a titanium alloy (Ti-6 AI-4 V) or stainless steel (SS), since neither of these promote osseointegration and can be easily removed when necessary. Nevertheless, there is a certain controversy over the use of one or the other type. While some authors, such as Park et  al.10 recommend the use of titanium alloys, Chang et al.7,8 recommend the use of surgical stainless steel because of its greater modulus of elasticity, providing resistance to fracture. Currently, several mini-implants with different shapes, diameters, lengths, and surface treatments are commercially available. Whether made of steel or titanium, they may have self-tapping or self-drilling properties. Selftapping screws require initial milling (perforation of the mucosa and cortical bone using a spear tip or clinical probe), because they have a rounded apex and no cutting capacity. Self-drilling screws, in turn, do not require prior drilling, since these screws are extremely thin and sharp, creating their own path inside the bone during placement, and facilitating simple placement. The thread length of the screws may vary from 4 to 12 mm, and the diameter may vary from 1.2 to 2 mm. Interradicular mini-implants are usually smaller and of reduced caliber, because of the possibility of injuring adjacent noble structures, such as the roots of the teeth. Conversely, E-A mini-implants are larger, both in length (10, 12, 14, 17 mm) and diameter (1.5–2 mm). Placement torque is influenced by the diameter of the mini-implants; that is, the larger the diameter, the greater the torque required for placement, and consequently, the greater the primary stability. Primary stability refers to the mechanical stability that mini-implants show, shortly after their apposition. It is a prerequisite for healing, and one of the

A

• Fig. 14.6  Extra-alveolar mini-implants used as for the retraction of the whole dentition to correct a bimaxillary protrusion.

B •

211

Fig. 14.5 (A and B) Unilateral Class II malocclusion treated with the infrazygomatic crest screw installed in the right side, where the case requires correction of the midline and also the molar relationship.

212 PA RT V I     Buccal TADs and Extra-Alveolar TADs

Since, in a clinical context, the E-A mini-implants are placed in a site with high bone density (cortical bone), initial perforation with a spear-tip or clinical probe is indicated in certain cases, even when using self-drilling orthodontic steel mini-implants. The aim of this procedure is to minimize the risk of fracture during placement. Motoyoshi et  al.13 reported that one of the ways to increase the primary stability of mini-implants in adolescents is to drill a small hole, a pilot hole, into the cortical bone before implant placement. Although there is a worldwide trend toward the use of surgical steel mini-implants for E-A placement, Almeida9 has successfully used a Brazilian kit (Morelli, Sorocaba, SP, Brazil), which is made of titanium. It should be noted that the placement technique differs according to whether the mini-implants are made of SS or titanium, as we will see later. The basic kit used by Almeida9 (Fig. 14.7), consisting of a hand-driver, long blade, and spear-tip, is the preferred kit because it contains all the material necessary for the placement of E-A mini-implants. Mini-implants have different lengths and diameters. Our suggestion is to use a longer

A

mini-implant, 10 mm in length, 1.5/2.0 mm in diameter, and with a 2-mm collar (transmucosal profile9). Despite having a small head and a round hole that prevents the correct activation of an inserted cantilever, rubber bands and springs made of nickel–titanium alloy can be placed simultaneously in the head of the screw, as shown in Fig. 14.8. The Peclab screw kit developed by Almeida9 is another option available in the Brazilian market (Peclab, Belo Horizonte, MG, Brazil). It is also made of titanium, with dimensions of 2 × 12 mm or 14 mm; it has a rectangular hole that allows correct adaptation and activation of a cantilever in situations of impacted canine traction. With a diameter of 2 mm and good placement torque, this mini-implants has been considered as a substitute for steel because of the encouraging results obtained with its use (Fig. 14.9). However, using SS mini-implants, in sites where bone density is typically high, may be useful. In this situation, a higher placement torque will occur, and thus a steel screw, as mentioned previously, having greater resistance to fracture, would be ideal.

B

C • Fig. 14.7  (A to C) Basic kit used by the author consisting of a hand-driver, a long blade, and a punch.

CHAPTER 14  Application of Extra-Alveolar Mini-Implants to Manage Various Complex Tooth Movements

In these cases, Chang et al.14 advocated the use of a steel mini-implant of 12 mm in length and 2 mm in diameter, with specific characteristics and the appropriate design for placement in IZC and BS areas. 

Placement Technique The mini-implant placement techniques in question (IZC and BS) depend on the material out of which the implants are made (steel or titanium), to increase the success rate (stability). In this regard, Chang and Roberts15 highlighted three key factors: (1) bone quality, (2) miniimplants design, and (3) placement technique, which are interrelated. 

•

Fig. 14.8 Despite having a small head and a round hole that prevents the correct activation of an inserted cantilever, rubber bands and springs made of nickel–titanium alloy can be placed simultaneously in the head of the screw.

213

Placement in the Infrazygomatic Crest The principles of biosafety must be strictly observed before the placement of the mini-implants. The angle of placement of the mini-implant in the IZC is fundamental. Park et al.10 evaluated the angle between the axis of the miniimplants and the cortical bone. They concluded that placing it almost parallel to the long root axis of the molars increases its contact surface with the cortical bone, guaranteeing greater stability. A more upright position of the mini-implant reduces the chance of reaching the root. Hsu et al.16 suggested the following steps for secure placement in the IZC: 1. Anesthetize the surgical area. 2. Initially, place the tip of the mini-implants at a 90-degree angle to the bone surface at the region of the IZC, after piercing the cortical bone at the mucogingival junction, using an endodontic explorer. 3. Penetrate the tip 1 mm into the cortical bone, at the height of the buccal roots, between the first and second upper molars in adults and in the region between the second premolar and the first molar in young people, since the zygomatic–maxillary crest in these individuals is located more anteriorly, as can be determined by local palpation. 4. Then, turn the hand wrench between 60 and 70 degrees to the occlusal plane, while rotating it clockwise, threading the mini-implants, as shown in Fig. 14.10. 5. The patient’s age, bone morphology, and the type of biomechanics to be performed should be considered. In the sagittal plane, that is, in the anteroposterior direction, position the head of the mini-implants, with a slight incline to the mesial direction. Fig. 14.11 demonstrates a correctly placed mini-implant for mesialization of the upper teeth. 

Placement in the Buccal Shelf

• Fig. 14.9  The Peclab screw developed by Almeida9 is another option

available in the Brazilian market (Peclab, Belo Horizonte, MG, Brazil). It is made of titanium, with dimensions of 2 × 12 or 14 mm; it has a rectangular hole that allows correct adaptation and activation of a cantilever, in situations of impacted canine traction. With a diameter of 2 mm and good placement torque, this mini-implants has been considered as a substitute for steel, because of the encouraging results obtained with its use.

Careful evaluation of the BS area should be performed before the placement of a mini-implants; the amount of bone present and the extent of gingiva, through which the mini-implants needs to be inserted, should be considered. Nucera et  al.17 and Elshebiny et  al.18 described a point located buccal to the distal root of the second lower molar, between 4 and 8 mm from the cementoenamel junction, as the best anatomic location for fixation. It is necessary to emphasize, however, that this area shows significant morphologic variation, and that some patients may have a welldemarcated bone plateau, while others do not, and have a bone profile that is practically straight. This difference can be clinically diagnosed by palpation or by cone-beam computed tomography (CBCT). One point to consider is the topography of the mandibular canal through which the inferior alveolar nerve travels. Because of its more lingual position relative to the apex of the roots of the lower molars, the chance of

214 PA RT V I     Buccal TADs and Extra-Alveolar TADs

A

B

C • Fig. 14.10  (A to C) Steps for secure placement of mini-implants in the infrazygomatic crest area.

• Fig. 14.11  Position of the head of the mini-implants with a slight inclination to the mesial direction to provide mesialization of the maxillary teeth.

reaching such a canal is remote, even with 2 × 12 mm mini-implants. For patients with a well-defined plateau and wellattached gingiva, placement of the mini-implant is much simpler; a sizeable BS allows the positioning of the miniimplants in a nearly vertical position, almost parallel to the root of the lower molars. The placement becomes more

difficult if the BS area is less favorable to placement, as the mini-implants should be placed at a higher angle and in a free mucosal site. Authors have argued for the use of the mini-implants in the BS, both in the attached gingiva and in free gingiva,14 depending, in the latter case, on more careful hygiene, to avoid possible inflammation and periimplant mucositis, with consequent anchorage instability. It should be emphasized that the attached gingiva range is larger in the region of the first lower molar, and decreases to the distal ends of the dental arch. Although the lower second molar region has more pronounced bone density, it is necessary to assess the best positioning of the miniimplants adequately, considering not only the bone density, but also other factors that will ensure greater stability to the mini-implant. 

Placement Technique As previously seen, the placement technique depends not only on the material from which the mini-implants are made but also on their design and the patient’s bone structure. 

CHAPTER 14  Application of Extra-Alveolar Mini-Implants to Manage Various Complex Tooth Movements

215

5. Low percentage of failure. 6. Use of fewer mini-implants in complex cases.

Precautions

• Fig. 14.12  Modification of the installation of the buccal shelf screw. In some situations, depending on the biomechanics, the mini-implants is inclined to the mesial plane to provide a mesialization of whole dentition.

Placement in the Buccal Shelf Region The placement technique follows the same procedures mentioned for the mini-implants placed in the IZC; that is, after following the principles of biosafety, it is necessary to perform local anesthesia and drill the cortical bone. Then the mini-implant is placed at the desired angle (70 degrees) relative to the occlusal plane. In some situations, depending on the biomechanics, the mini-implants is inclined to the mesial plane, as shown in Fig. 14.12. 

Magnitude of the Force Applied The magnitude of the mechanical force with which E-A mini-implants are placed is an important factor for the success of the therapy because it influences the stability of the anchorage, as many authors have pointed out.9,14,16,19 The recommended weight for orthodontic mechanics using mini-implants, in the region of the IZC, ranges from 220 to 340-g (8 to 12 oz) and from 340 to 450-g, when miniimplants are used in the BS area. 

Benefits Contemporary orthodontics has used E-A mini-implants, located in areas far from the insertion points of the roots of the teeth, to extend the limits of this treatment, in view of the benefits of this approach, such as: 1. Reduced risk of traumatizing roots. 2. Larger amount of cortical bone at the points of placement, which allows the use of more flexible miniimplants (2 mm). 3. Lack of interference with the mesiodistal movement of the teeth. 4. Adequate anchorage for the retraction of the dental arch as a whole, reducing protrusion.

1. Preferably place the mini-implants in the attached gingiva. 2. Respect general principles of biosafety. 3. Maintain strict hygiene at the site of implantation, especially in cases where the mini-implants are placed, in the area of transition, from attached gingiva towards movable mucosa. 4.  Maintain the correct angle when placing the miniimplant, to avoid injuring the roots, in both the upper and lower teeth. 5. When the implanted region is that of the zygomatic– alveolar crest, avoid the possibility of reaching the maxillary sinus (although this seems not to be a problem). 6. In cases of distalization of lower second molars, use panoramic x-ray or CBCT to verify that there is sufficient space for this movement. 7. In young people, mini-implants are placed more anteriorly (in the region of the first molar, IZC 6) and higher (vertical), to prevent the possibility of lesioning the root of the tooth. Often the positioning is done in the free gingiva (mobile mucosa), taking the above-mentioned precautions. 8. Clinically, in cases of doubt, preevaluate the placement of the mini-implant, both in the IZC region and the BS region, using CBCT. The clinical case presented subsequently is that of a patient with Class III malocclusion, anterior openbite, and crowding of the incisors, which was treated by extracting the lower third molars and by bilateral placement of mini-implants in the BS region, between the first and second lower molars, as for the retraction of whole mandibular dentition (Fig. 14.13). 

Final Considerations Given that the technique for placing mini-implants in the IZC and BS regions involves surgery, the practitioner responsible for this maneuver must thoroughly investigate all the risk factors of this process to ensure the safety of the patient. Although this absolute anchorage is efficient, it involves risk to nearby anatomic structures, especially the maxillary sinus and inferior alveolar nerve. Recent studies20 have shown that the success rate of long mini-implants placed in the IZC is 96.7%, with 78.3% of them penetrating the maxillary sinus. However, the authors draw attention to the fact that it is recommended that this penetration does not exceed 1 mm. Similarly, Elshebiny et al.18 has indicated that the most favorable site for the correct positioning of the mini-implant in the BS area, to avoid trauma to the alveolar trigeminal branch, is the site corresponding to the distobuccal portion of the lower second molar.

216 PA RT V I     Buccal TADs and Extra-Alveolar TADs

A

B

C

D

E

F

G •

Fig. 14.13 (A to H) Male patient of 16 years of age, Class III malocclusion, concave profile, anterior openbite, and crowding in both arches. (I to K): The resolution of the malocclusion occurs with a buccal shelf mechanics to distalize the whole dentition backward. A power-chain was hooked to the titaniummolybdenium alloy (TMA) 0.017 × 0.025-inch mandibular arch with a long hook and 350-g of force each side. The duration of the distalization of mandibular arch was 7 months. Total treatment time was 17 months. (L to S): At the completion of the case, we can see a good intercuspation of posterior teeth and also a good facial profile.

CHAPTER 14  Application of Extra-Alveolar Mini-Implants to Manage Various Complex Tooth Movements

H

I

J

L

K

M

N • Fig. 14.13 cont’d

217

218 PA RT V I     Buccal TADs and Extra-Alveolar TADs

O

P

Q

R

S • Fig. 14.13 cont’d

References 1. Cheng SJ, Tseng IY, Lee JJ, Kok SH: A prospective study of the risk factors associated with failure of mini implants used for orthodontic anchorage, Int J Oral Maxillofac Implants 19(1):100– 106, 2004. 2. Park HS, Lee SK, Kwon OW: Group distal movement of teeth using microscrew implant anchorage, Angle Orthod 75(4):602– 609, 2005.

3. Almeida MR, Almeida PR, Chang C: Biomecânica do tratamento compensatório da má-oclusão de Classe III utilizando ancoragem esquelética extra-alveolar, Rev Clín Ortod Dental Press 15(2):74–76, 2016. 4. Almeida MR, Almeida PR, Nanda R: Biomecânica dos miniimplantes inseridos na região de crista infrazigomática para correção de má-oclusão de Classe II subdivisão, Rev Clin Ortod Dental Press 15(6):90–105, 2017.

CHAPTER 14  Application of Extra-Alveolar Mini-Implants to Manage Various Complex Tooth Movements

5. Almeida MR: Biomecânica de distalização dentoalveolar com mini-implantes extra-alveolares em paciente Classe I com biprotrusão, Rev Clin Ortod Dental Press 16(6):61–76, 2017. 6. Costa A, Raffainl M, Melsen B: Mini-screws as orthodontic anchorage: a preliminary report, Int J Adult Orthodon Orthognath Surg 13(3):201–209, 1998. 7. Chang CH: Clinical applications of orthodontic bone screw in Beethoven orthodontic center, Int J Orthod Implantol 23:50–51, 2011. 8. Chang C, Huang C, Roberts E: 3D cortical bone anatomy of the mandibular buccal shelf: a CBCT study to define sites for extraalveolar bone screws to treat Class III malocclusion, Int J Orthod Implantol 41(1):74–82, 2016. 9. Almeida MR: Mini-implantes extra-alveolares em Orrtodontia, ed 1, Maringá, 2018, Dental Press. 10. Park HS, Jeong SH, Kwon OW: Factors affecting the clinical success of screw implants used as orthodontic anchorage, Am J Orthod Dentofacial Orthop 130(1):18–25, 2006. 11. Lemieux G, et  al.: Computed tomographic characterization of mini-implant placement pattern and maximum anchorage force in human cadavers, Am J Orthod Dentofacial Orthop 140(3):356– 365, 2011. 12. Chen CH, Chang CS, Hsieh CH, Tseng YC, Shen YS, Huang IY, et al.: The use of microimplants in orthodontic anchorage, J Oral Maxillofac Surg 64(8):1209–1213, 2006. 13. Motoyoshi M, Matsuoka M, Shimizu N: Application of orthodontic mini-implants in adolescents, Int J Oral Maxillofac Surg 36(8):695–699, 2007.

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14. Chang C, Liu SS, Roberts WE: Primary failure rate for 1680 extra-alveolar mandibular buccal shelf mini-screws placed in movable mucosa or attached gingiva, Angle Orthod 85(6):905– 910, 2015. 15. Chang CH, Roberts WE: A retrospective study of the extra-alveolar screw placement on buccal shelves, Int J Orthod Implantol 32:80–89, 2013. 16. Hsu E, Lin JSY, Yeh HY, Chang C, Robert E: Comparison of the failure rate for infra-zygomatic bone screws placed in movable mucosa or attached gingiva, Int J Orthod Implantol 47(1):96– 106, 2017. 17. Nucera R, Lo Giudice A, Bellocchio AM, Spinuzza P, Caprioglio A, Perillo L, et al.: Bone and cortical bone thickness of mandibular buccal shelf for mini-screw insertion in adults, Angle Orthod 87(5):745–751, 2017. 18. Elshebiny T, Palomo JM, Baumgaertel S: Anatomic assessment of the mandibular buccal shelf for mini-screw and insertion in white patients, Am J Orthod Dentofacial Orthop 153:505–511, 2018. 19. Hsieh YD, Su CM, Yang YH, Fu E, Chen HL, Kung S: Evaluation on the movement of endosseous titanium implants under continuous orthodontic forces: an experimental study in the dog, Clin Oral Implants Res 19(6):618–623, 2008. 20. Jiay, Chen X, Huang X: Influence of orthodontic mini-implant penetration of the maxillary sinus in the infrazygomatic crest region, Am J Orthod Dentofacial Orthop 153(5):656–661, 2018.

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PART VII

Management of Multidisciplinary and Complex Problems 15. Management of Skeletal Openbites With TADs Flavio Uribe and Ravindra Nanda 16. Orthognathic Camouflage With TADs for Improving Facial Profile in Class III Malocclusion Eric JW. Liou 17. Management of Multidisciplinary Patients With TADs Flavio Uribe and Ravindra Nanda 18. Second Molar Protraction and Third Molar Uprighting Un-bong Baik 19. Class II Nonextraction Treatment With MGBM System and Dual Distal System B. Giuliano Maino, Giovanna Maino, Luca Lombardo, John Bednar and Giuseppe Siciliani 20. Anchorage of TADs Using Aligner Orthodontics Treatment for Lower Molars Distalization Kenji Ojima, Junji Sugawara and Ravindra Nanda

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15

Management of Skeletal Openbites With TADs FLAVIO URIBE, RAVINDRA NANDA

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nterior openbite is perhaps the type of malocclusion in which the use of temporary anchorage devices (TADs) has been advocated more frequently. The great success outcomes reported in the early years of this new century drew clinicians to consider the application of TADs for the correction of skeletal openbite malocclusions, where traditionally, surgery had been the only option. These remarkable results showed for the first time that predictable molar intrusion was attainable. Before TADs, molar intrusion had been described as relatively difficult to achieve or limited at best. The approaches for molar intrusion to control the vertical dimension before the advent of skeletal anchorage relied on appliances that prevented the eruption of posterior teeth during growth. Some of these appliances were bite plates,1,2 magnets,3 chin cups,4,5 high pull headgears,6 and combination of these appliances.7 Although positive effects were observed in the correction of the anterior openbite, these were primarily dentoalveolar, consisting in the eruption of the incisors as main driver of the positive occlusal change.5 Prior to the TADs era, the adult patient with a skeletal openbite requiring intrusion of the posterior teeth to control the vertical dimension had to resort to orthognathic surgery. The Multiloop Edgewise Archwire (MEAW) technique was one of the first techniques that was proposed as a nonsurgical method to correct skeletal openbites.8 Unfortunately, the true effects of this appliance primarily effected the incisors with extrusion, instead of the expected molar intrusion.9 Later, the use of skeletal anchorage through miniplates on all quadrants was published and the significant results evoked the attention of orthodontic clinicians.10,11 Mini-implants were later introduced to achieve buccal segment intrusion with a simplified insertion protocol12 and thus allowed the orthodontist the placement of these temporary anchorage devices, instead of relying on a surgeon. More than 20 years have transpired since the advent of skeletal anchorage, and many different approaches have been advocated for the correction of the anterior openbite malocclusion and control of the vertical dimension. The primary target of these appliances has been the maxillary molars.13 Two basic systems have been described to achieve molar intrusion:

mini-implants and miniplates. Although miniplates have been reported to have slightly better success rates compared to mini-implants,14 these have limited locations for placement. Specifically, for the control of the vertical dimension, miniplates are placed in the infrazygomatic (IZ) crest in the maxilla and in the buccal crest of the corpus of the mandible. On the other hand, mini-implants can be placed in the same sites, and also include interradicular and palatal anatomic locations to deliver the desired intrusive force system to the molars. Mini-implants are certainly more popular than miniplates because of the ease of placement, ease of replacement, no need for elevating a flap during placement and removal, and overall reduced costs. Furthermore, as described earlier, more locations are available for placement of mini-implants. Since many anatomic locations are available, which one is the best suited when molar intrusion is required to reduce the lower facial height and correct an anterior openbite malocclusion? Certainly, the answer to this question lies in the clinician’s preference, but perhaps more important, the biomechanical considerations are key to determine the best mini-implants location and thus the most effective force system to be applied.

Biomechanics of Molar Intrusion in Skeletal Openbites It is common knowledge in orthodontics that we are typically unable to apply a force at the center of resistance of a tooth. This is the case when we are describing force systems that are applied in anteroposterior direction along the arch. On the other hand, when the force system, such as an intrusive force, is applied from a sagittal point of view, it is possible to apply this force through the estimated center of resistance of a tooth or a group of teeth, at least when analyzed from a sagittal plane. However, when this applied force is analyzed from a frontal plane, this force generates a moment, since it is not through the center of resistance. If we consider maxillary first and second molars to be intruded bilaterally, it is clear, from a sagittal plane perspective, that a force applied at the bracket level of the first and second 223

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• Fig. 15.1  Buccal rolling of posterior segments with intrusion from infrazygomatic (IZ) mini-implants. (A–C)

Intraoral photos of an anterior openbite, where the occlusal planes diverge anteriorly from the first premolars. (D–F) Buccal force from the IZ mini-implants created a premature contact of the molar cusps of the molars, preventing openbite closure. A buccal crossbite tendency also developed.

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• Fig. 15.2  Control of the molars in a buccolingual direction. (A) Two palatal mini-implants and two extension

arms, fabricated from a framework, were placed to deliver an intrusive and lingual force vector to the maxillary molars. (B) Molar lingual cusps have intruded with these mechanics, allowing for anterior openbite reduction.

molar would be very close to the estimated center of resistance of these four teeth, and thus would intrude without expressing a rotational moment in this plane. On the other hand, when this force is analyzed from the frontal plane, the intrusive force at the level of the molar tubes would generate a moment on these teeth that will tend to erupt the palatal cusps, preventing the correction of the openbite (Fig. 15.1). To counteract this rotational moment, two options are available. The first one is the application of the same force magnitude in the same anteroposterior location, but from the palatal side (Fig. 15.2). The other alternative is the placement of a transpalatal arch, which requires to be placed away from the palatal vault, to allow space for the apical displacement of the transpalatal bar, as the molars are intruded. To deliver this described intrusive force to the first and second molars, the IZ crest area provides the best location. Typically, the crest is located slightly mesial to the second molar, therefore a slight mesial component of the force is expected if the force is delivered only to the second molars. An alternative is to place an interradicular mini-implant

between the first and second molar, if enough space is available between these two teeth for placement. If the force is to be delivered from the palatal side only, the mini-implant can be also placed mesial to the palatal root of the second molar. This location has the advantage of increased space for placement of the mini-implant. In addition, the clinician must be aware that the palatal foramen is in the vicinity of the second molar in some individuals,15 and therefore caution is required when placing a mini-implant in this location. An advantage of delivering a force from the lingual side of the molars is that the palatal cusp can be controlled easier with this point of force application. Furthermore, if palatal constriction is evident, a palatal expansion screw could be placed to expand, as needed, to control the lingual tip tendencies, with the intrusive forces. The anatomy of the openbite is an important consideration when intrusion of the buccal segment is desired in patients with skeletal openbites. If the occlusal plane of the maxillary and mandibular arches diverge from the first/ second molars anteriorly, the application of a force vector

CHAPTER 15  Management of Skeletal Openbites With TADs

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• Fig. 15.3  Palatal molar intrusion on an openbite, with anteriorly diverging occlusal planes from the pre-

molars. Lateral cephalogram (A) and intraoral photographs (B–D) depicting moderate to severe anterior openbite, with occlusal contacts on the molars and second premolars. (E) Two palatal mini-implants were placed between the first and second molars. A palatal expansion screw with occlusal rests on the second molars was cemented on the first molars to control the transverse dimension. (F–H) Reduction of the anterior openbite, after maxillary molar intrusion and placement of continuous arches.

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L Fig. 15.3, cont’d  (I–K) Final occlusal result. (L) Although molar intrusion was achieved, significant extrusion of the incisors is noticed on the maxillary superimposition.

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Fig. 15.4 Horizontal vector with intrusive force from infrazygomatic (IZ) mini-implant. As molars are intruded from an IZ mini-implant, the force vector can become more horizontal than vertical, resulting in less molar intrusion and more buccal expansion on the maxillary arch.

to these two teeth bilaterally is advantageous, as a wedge effect is expected with the intrusion of these terminal teeth in the arch. However, when the occlusal planes diverge anteriorly from the first premolar, the biomechanics of this correction is more complex. In this scenario, a single labial or lingual vertical force applied to the second/first molar region would tend to rotate the posterior segment in a clockwise direction along the sagittal plane, with the intrusion of the first and second molars, creating a posterior openbite in this location, while the premolars remain in contact. A way to prevent this from happening is through a force applied to the second molar and another separate force applied to the second or first premolar (from the IZ region). This force system can control better the rotation of the segment from a sagittal perspective; however, a net force vector with a distal direction is generated, which may

be advantageous in a Class II malocclusion, but not in a Class III malocclusion. Furthermore, since the premolars typically do not receive a transpalatal arch, a stiff full archwire needs to be placed to counteract the labial rotational moment on these teeth. The same problem can be observed if the vertical force is applied from the palate at the level of the second molar. The patient in Fig. 15.3 presented with a significant anterior openbite that diverged anteriorly from the second premolars. Two Lomas mini-implants (Mondeal Medical Systems, Donau, Germany) were placed in the palate between the first and second molars. A palatal arch with an expansion screw was delivered to the maxilla to counteract the moment of the intrusive force to the molars. In addition, an occlusal rest was added to the second maxillary molars to aid with the intrusion of these teeth as the force was applied to a hook in the appliance between the two molars. Molar intrusion and anterior openbite closure were obtained until the first premolars and the canine started to contact occlusally. At this point, more intrusion was not possible and extrusion of the incisors had to be effected. Although closure of the openbite was achieved, the maxillary superimposition shows that the molar intrusion was approximately 1 to 2 mm. Nonetheless, despite these molar intrusion, majority of the correction was achieved by eruption of the maxillary central incisors. Another problem may be also encountered when intruding maxillary molars from IZ mini-implants. As intrusion is obtained, the vector of the force becomes more horizontal and thus less effective. This is more obvious if the attachment head of the mini-implant is placed somewhat labial

CHAPTER 15  Management of Skeletal Openbites With TADs

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• Fig. 15.5  Distalization from infrazygomatic (IZ) mini-implants. (A–C) Distalization force vector from IZ mini-

implants to correct the Class II buccal occlusion. (D–F) Reduction of overjet and improvement of the anterior openbite observed.

from the buccal surface of the molars as shown in Fig. 15.4. The solution to this problem is to place the IZ miniimplants in more apical position; however, there is anatomic limitations in doing so, and often a better force vector may be obtained from the palatal side. There is, however, one advantage to the IZ mini-implant for molar intrusion. If a distalization force vector is desired in conjunction with the maxillary intrusion, it is much easier to deliver this force from the labial aspect than from the lingual aspect. Fig. 15.5 shows the same patient in Fig. 15.1, where the occlusion is Class II on the canine, requiring distalization. A labial power arm is placed on the archwire distal of the canine to achieve this distal movement of the buccal segment.

Case Report One To account for all these potential pitfalls with buccal segment intrusion in patients with occlusal planes diverging anteriorly from the premolars, we have designed an appliance that provides versatility in the application of the required force vectors. The appliance is fabricated from two 1.8 × 8-mm IMTEC Ortho mini-implants (3M Unitek, Ardmore, Okla) placed at the level of the second premolars and first molars, from which four extension arms project with hooks that allow the delivery of specific targeted forces depending on the biomechanical needs. A 13-year-old male patient, displayed in Fig. 15.6, shows a significant convex profile, with an openbite that diverges anteriorly from the first premolars. The incisor display at rest was adequate, so intrusion of the maxillary buccal segment was required to correct the openbite while maintaining the incisor position vertically. Because of the significant amount of crowding,

the first premolars were also extracted. Intrusive forces were delivered to the molars from the four extension arms in the palate. The versality of this appliance relies on the possibility to intrude both the molars and/or premolars, as needed, with a vertical force vector. In addition, anteroposterior forces for mesialization or distalization of the buccal segments may be delivered unilaterally or bilaterally. During the intrusion process of the molars, the palatal forces being delivered generate a moment to rotate the teeth buccolingually, which can create a crossbite. To account for this, two options are available. The first one is to place a full engagement base, stainless steel archwire, on the labial aspect (0.021 × 0.025-inch stainless steel), with slight expansion. The second option involves the placement of a palatal arch or palatal expander appliance, which was the option used in the following case. A palatal expander screw is designed with bands in the first molars. The expansion screw needs to rest approximately 5 mm from the palatal vault to allow displacement of the molars in a superior direction. The appliance can also incorporate wire extensions to the occlusal surface of the second molars, to intrude these teeth in synchrony with the first molars, without having to bond them. In the same manner, extension arms projecting anteriorly are extended along the lingual surfaces of premolars and an occlusal stop is also added to the first premolars. Although a bondable metal mesh base pad could be added to the second premolars to be able to intrude the whole buccal segment without labial appliances, the bonding of this tooth to the appliance is problematic and often fails. In this instance, a labial full arch may be engaged to the buccal segments, bypassing the anterior teeth, engaging the second premolars. Fig. 15.7 shows these precise mechanics. 

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I J • Fig. 15.6  Versatile palatal temporary anchorage device (TAD) supported mini-implant device for intrusion

of the buccal segments and delivery of anteroposterior forces. Pretreatment extraoral (A–C) and intraoral (D–H) photographs. (I) Pretreatment cephalogram. (J) Palatal supported framework with four extension arms derived from two palatal mini-implants. Parallel intrusion of the buccal segment can be achieved with this mechanics.

CHAPTER 15  Management of Skeletal Openbites With TADs

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R Fig. 15.6, cont’d  (L–N) Preintrusion occlusion, after four premolar extractions and placement of continuous archwires. (O–Q) Postintrusion occlusion, after the delivery of intrusive forces. (R) Anteroposterior force delivered to the left premolar from the lingual side for Class II correction.

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Y Fig. 15.6, cont’d (S–X) Posttreatment extraoral and intraoral photos and lateral cephalogram (Y).

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• Fig. 15.7  Palatal TADs-supported appliance with full control of the buccal segments for parallel intrusion.

(A) Palatal TADs-supported appliance (from two mini-implants) with four extension arms for control of the force vector delivery. Palatal expansion screw with occlusal stops on the second molars and first premolars. Second premolars could be bonded to the palatal expander framework; however, this bond tends to fail. Labial brackets can help to control the position of these teeth when bonding fails. (B–D) Intraoral photos showing significant anterior openbite, with occlusal planes diverging anteriorly from the second premolars. (E) Intrusion both at the level of the first premolars and molars. (F–H) Significant reduction of the anterior openbite, with levelling of the maxillary occlusal plane.

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Vertical Control With Palatal TADs in the Growing Patient An interesting approach, in the vertical dimension control, is the intrusion of the buccal segments in growing patients, with skeletal openbite features. These patients present with a convex profile tendency, long lower facial height, a Class II malocclusion, and a tendency to an anterior openbite. It has been reported that adequate vertical control can be achieved in these patients, who can benefit from the resulting

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anteroposterior projection of the mandible.16 The molar intrusion forces can also prevent further clockwise rotation of the facial complex. The positive vertical effects would also aid in the correction of the Class II malocclusion, as a more favorable horizontal growth pattern is achieved.

Case Report Two Fig. 15.8 shows a 13-year-old boy with a slightly convex profile, long lower facial height, Class II malocclusion, with

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G • Fig. 15.8  Vertical control of the maxillary molars in a growing patient with a long face skeletal pattern. Pretreatment extraoral (A–C) and intraoral (D–F) photographs (G) Pretreatment lateral cephalogram.

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Fig. 15.8, cont’d  (H) Palatal TADs-supported appliance for parallel intrusion of the buccal segment. Arms extended anteriorly and bonded to both premolars bilaterally. (J–L) Openbite after inserting the appliance related to the occlusal rest on the second molars. (M–O) Intraoral photos showing positive overbite and an improved anteroposterior relationship of the buccal segments.

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Fig. 15.8, cont’d  (P) Profile photo showing the progress in profile change, with the molar intrusion. (Q) TAD appliance holding the first molars vertically while the finishing stage is being completed. (R–T) Occlusal relationship in the finishing phase. (U) Progress of the facial profile change.

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Fig. 15.8, cont’d  Posttreatment lateral cephalogram (Zd) and superimposition (Ze).

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Fig. 15.9 Mandibular molar intrusion. (A) Lateral cephalogram showing significant anterior openbite, with occlusal planes diverging anteriorly from second molars. (B–C) Mandibular molar intrusion delivered from TADs in the molar region. (D–F) Final intraoral photographs depicting the correction of the anterior openbite.

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H J Fig. 15.9, cont’d  Cranial base (H), maxillary (I) and mandibular (J) superimpositions, showing the intrusion of the mandibular molars and the significant autorotation of the mandible.

anterior openbite tendency, and approximately 6 mm of overjet. A maxillary intrusion appliance targeting the posterior buccal segment was prescribed for vertical translatory movement of the posterior teeth, with the intent of obtaining more horizontal mandibular growth. The positive effect of the appliance in the correction of the malocclusion and favorable facial change is evident. It should be noted that although there was adequate control of the eruption of the maxillary molars, the mandibular molars erupted significantly with growth. Nonetheless, favorable growth direction was observed with this approach, which facilitated obtaining a good occlusal result. 

Mandibular Molar Intrusion in Openbite Correction Majority of the efforts in the correction of the anterior openbite, through molar intrusion, has been achieved by targeting the maxillary molars. Sole intrusion of the mandibular molars to correct an anterior openbite has been seldomly reported.17 It appears that this intrusive movement of the mandibular molars could be difficult to achieve. However, in a patient with a significant divergent occlusal planes, it may be possible to effect significant changes with minor molar intrusion. Fig. 15.9 shows an adult male patient with occlusal plane diverging from the second molars. Third molars were extracted and intrusion of the second molar was achieved, with the placement of an

interradicular mini-implants on the labial aspect between the left first and second molar and a miniplate in a similar anteroposterior location on the right side, after the failure of two consecutively placed mini-implants. The final result shows the significant anterior openbite correction shown in the superimposition. This result, however, took a significantly long time to achieve (over a 3-year period), and the panoramic radiograph shows moderate root resorption in the distal roots of both second molars. It has been suggested that when intruding the maxillary molars, it may be necessary to hold vertically the supraeruption of the lower molars, by placing mini-implants or miniplates in the mandible.18 Mini-implants can be placed between the first and second molars and a light force applied to control the eruption of the lower teeth. This approach is recommended if significant mandibular projection is desired, as the maxillary molar intrusion is being achieved, since full vertical control can be obtained. 

Correction of Anterior Openbites Through Incisor Extrusion With TADs Although the primary target of skeletal anchorage in the treatment of the openbite malocclusion has been the molars, TADs could also be used as a tool to control the side effects of incisor extrusion arch mechanics in these patients, especially in the noncompliant patient that does not wear intermaxillary elastics.19

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Case Report Three Fig. 15.10 shows a patient with excellent buccal occlusion and anterior openbite. Interradicular mini-implants were placed in all the quadrants and a sectional wire was placed from these TADs to the first molars for indirect anchorage.

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An extrusion arch was delivered to extrude the maxillary and mandibular incisors. The mesial tip moment on the maxillary and mandibular first molars that resulted from the extrusive force of the extrusion arch was controlled by indirect anchorage, drawn from the mini-implant in each quadrant.

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G • Fig. 15.10  Temporary anchorage devices (TADs) for incisor extrusion and correction of the anterior openbite. Pretreatment extraoral (A–C) and intraoral (D–F) photographs. (G) Pretreatment cephalogram showing good buccal occlusion and anterior openbite diverging from the first premolars anteriorly.

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Fig. 15.10, cont’d  Progress intraoral photographs showing extrusion arches applied from all the first molars which are being anchored indirectly by interradicular mini-implants. (H–J) Initiation of incisor extrusion; (K–M) 3 months of active incisor extrusion.

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T Fig. 15.10, cont’d  Posttreatment extraoral (N–P) and intraoral (Q–S) photographs and lateral cephalogram (T). (From: Librizzi ZT, Janakiraman N, Rangiani A, Nanda R, Uribe FA. Targeted mechanics for limited posterior treatment with mini-implant anchorage. J Clin Orthod. 2015;49(12):777-783.) 

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• Fig. 15.11  Temporary anchorage devices (TADs) to control the mesial tip moment on the maxillary molar

with incisor extrusion. (A) Maxillary TADs-supported habit appliance delivering indirect anchorage to the first molar. (B–D) Extrusion arch extended to the incisors from the first molars. (E–G) Mesial tip observed on the maxillary molars, premolars and canines, when a buccal segment was extended from the first molars to the canines. The molar mesial tip tendency from the extrusive force to the incisors was not counteracted by the cemented palatal appliance.

• Fig. 15.12  Three mini-implant Palatal Appliance.  Three mini-implants

placed in the maxilla, as an example of an option to control the mesial tipping moment on the molars, with the extrusive force applied to the incisors, when using temporary anchorage devices (TADs) with round attachment heads.

It is important to highlight that indirect anchorage may not suffice in the control of the mesial moment on the molars. Patient in Fig. 15.11 shows an extrusion arch delivered from the first molars. When the mesial tip of the molars was observed, two palatal IMTEC Ortho mini-implants (3M Unitek, Ardmore, Okla) were placed and a transpalatal

bar was delivered, engaging these mini-implants and the molars. Since the attachment head of these mini-implants was round, the cemented attachment cap of the appliance was not able to resist the moment generated at the molar level, from the extrusion arch, and the TADs were ineffective to counteract the mesial tip. Perhaps an attachment head with a vertical wall or a screw retained attachment head could better resist these rotational tendencies observed with extrusion of the incisors, when mini-implants are placed in the palate and indirect anchorage is prescribed in this manner. A final option could be adding a third mini-implant in the palate, to counteract this mesial moment (Fig. 15.12). 

Conclusion Maxillary molar control, through intrusive force vectors from TADs, have been the main strategy to control the vertical dimension and correct skeletal openbites. The anatomy of the openbite should be considered to apply the proper force vectors. Although many skeletal anchorage options are available, the required force vector should be matched to

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the appropriate TAD delivery system for each clinical situation. Mandibular molar intrusion may be a useful strategy to complement maxillary molar intrusion if a significant facial change is desired. Finally, TADs could be also used for incisor extrusion, by means of an extrusion arch, in patients with anterior openbites, with a small skeletal vertical component, who are noncompliant patients and adequate intermaxillary elastic wear is lacking.

Acknowledgments We would like to acknowledge all the residents and faculty who participated in the treatment of these cases.

References 1. Iscan HN, Sarisoy L: Comparison of the effects of passive posterior bite-blocks with different construction bites on the craniofacial and dentoalveolar structures, Am J Orthod Dentofacial Ortho 112:171–178, 1997. 2. Kuster R, Ingervall B: The effect of treatment of skeletal open bite with two types of bite-blocks, Eur J Orthod 14:489–499, 1992. 3. Kiliaridis S, Egermark I, Thilander B: Anterior open bite treatment with magnets, Eur J Orthod 12:447–457, 1990. 4. Pedrin F, Almeida MR, Almeida RR, Almeida-Pedrin RR, Torres F: A prospective study of the treatment effects of a removable appliance with palatal crib combined with high-pull chincup therapy in anterior open-bite patients, Am J Orthod Dentofacial Orthop 129:418–423, 2006. 5. Torres F, Almeida RR, de Almeida MR, Almeida-Pedrin RR, Pedrin F, Henriques JF: Anterior open bite treated with a palatal crib and high-pull chin cup therapy. A prospective randomized study, Eur J Orthod 28:610–617, 2006. 6. Dermaut LR, van den Eynde F, de Pauw G: Skeletal and dentoalveolar changes as a result of headgear activator therapy related to different vertical growth patterns, Eur J Orthod 14:140–146, 1992. 7. Pisani L, Bonaccorso L, Fastuca R, Spena R, Lombardo L, Caprioglio A: Systematic review for orthodontic and orthopedic treatments for anterior open bite in the mixed dentition, Prog Orthod 17:28, 2016.

8. Kim YH: Anterior openbite and its treatment with multiloop edgewise archwire, Angle Orthod 57:290–321, 1987. 9. Kim YH, Han UK, Lim DD, Serraon ML: Stability of anterior openbite correction with multiloop edgewise archwire therapy: a cephalometric follow-up study, Am J Orthod Dentofacial Orthop 118:43–54, 2000. 10. Sherwood KH, Burch JG, Thompson WJ: Closing anterior open bites by intruding molars with titanium miniplate anchorage, Am J Orthod Dentofacial Orthop 122:593–600, 2002. 11. Umemori M, Sugawara J, Mitani H, Nagasaka H, Kawamura H: Skeletal anchorage system for open-bite correction, Am J Orthod Dentofacial Orthop 115:166–174, 1999. 12. Kuroda S, Katayama A, Takano-Yamamoto T: Severe anterior open-bite case treated using titanium screw anchorage, Angle Orthod 74:558–567, 2004. 13. Alsafadi AS, Alabdullah MM, Saltaji H, Abdo A, Youssef M: Effect of molar intrusion with temporary anchorage devices in patients with anterior open bite: a systematic review, Prog Orthod 17:9, 2016. 14. Yao CC, Chang HH, Chang JZ, Lai HH, Lu SC, Chen YJ: Revisiting the stability of mini-implants used for orthodontic anchorage, J Formos Med Assoc 114:1122–1128, 2015. 15. Tomaszewska IM, Tomaszewski KA, Kmiotek EK, Pena IZ, Urbanik A, Nowakowski M, et  al.: Anatomical landmarks for the localization of the greater palatine foramen—a study of 1200 head CTs, 150 dry skulls, systematic review of literature and meta-analysis, J Anat 225:419–435, 2014. 16. Buschang PH, Carrillo R, Rossouw PE: Orthopedic correction of growing hyperdivergent, retrognathic patients with miniscrew implants, J Oral Maxillofac Surg 69:754–762, 2011. 17. Freitas BV, Abas Frazao MC, Dias L, Fernandes Dos Santos PC, Freitas HV, Bosio JA: Nonsurgical correction of a severe anterior open bite with mandibular molar intrusion using mini-implants and the multiloop edgewise archwire technique, Am J Orthod Dentofacial Orthop 153:577–587, 2018. 18. Hart TR, Cousley RR, Fishman LS, Tallents RH: Dentoskeletal changes following mini-implant molar intrusion in anterior open bite patients, Angle Orthod 85:941–948, 2015. 19. Librizzi ZT, Janakiraman N, Rangiani A, Nanda R, Uribe FA: Targeted mechanics for limited posterior treatment with miniimplant anchorage, J Clin Orthod 49:777–783, 2015.

16

Orthognathic Camouflage With TADs for Improving Facial Profile in Class III Malocclusion ERIC JW. LIOU

T

he treatment of Class III malocclusion includes surgical orthodontics,1–4 or orthodontic camouflage treatment.5–7 Orthodontic camouflage treatments, such as protraction of upper dentition and/or retraction of lower dentition through extraction or nonextraction therapy, improve the anterior crossbite in patients with Class III malocclusion.8–11 The scope of Class III orthodontic camouflage treatment expands after the temporary anchorage devices (TADs) have been included.9–11 Orthodontic retraction of lower dentition also retracts lower lip and relatively worsens chin projection and mandibular prognathism.12 The goal of Class III orthodontic camouflage treatment should be to improve both occlusion and facial profile. However, mandibular prognathism is difficult to camouflage orthodontically. An innovative concept of “orthognathic camouflage”13 by orthodontic backward rotation of mandible, to decrease chin projection, in treating either growing or adult patients with Class III malocclusion has been proposed. This concept is not new. It originated from the clockwise rotation of maxillomandibular complex by orthognathic surgery, for the improvement of Class III facial profile,14–16 as well as from the opposite, the orthodontic intrusion of posterior teeth with TADs, for the correction of anterior openbite and improvement of mandibular retrognathism in Class II openbite patients.17,18 Orthognathic camouflage, by backward rotation of mandible, for patients with Class III malocclusion, is to extrude the upper and/or lower dentitions, for improving upper incisor show and smile arc, and subsequently to backward rotate the mandible to decrease chin projection and mandibular prognathism. Three techniques, including bimaxillary or single-dentition extrusion with or without TADs, have been developed. They could be used in either nonextraction or extraction, growing or adult patients.

Bimaxillary Extrusion Without TADs This is a technique of orthodontic backward rotation of mandible, with bite raisers and vertical elastics. The strategy is to place bite raisers/blocks on posterior teeth to open the bite and backward rotate the mandible to the planned position, and then the anterior openbite is closed, via bimaxillary extrusion of the upper and lower dentitions, by using intermaxillary vertical elastics (Figs. 16.1 and 16.2).

Preparation A segmental maxillary archwire from second premolar to second premolar with anterior labial crown torque is placed, and another two segmental archwires are placed on both sides of the maxillary first and second molars. A transpalatal arch (TPA) is placed to consolidate the maxillary posterior teeth. A continuous archwire and a lingual holding arch are then placed in the mandibular dentition. 

Placement of Bite Raisers to Backward Rotate Mandible The material for bite raisers could be a light-cured composited resin or glass ionomer (GI) band cement. For the ease of saliva control, bite raisers placement, and their removal, it is recommended to use light-cured GI band cement and bond them on both sides of upper posterior teeth. The occlusal surfaces of upper molars on both sides are first cleaned with pumice powder, and then the central fossae of the upper molars, but not the entire occlusal surface, are conditioned with etching agent. The etching process at the central fossae ensures retention of the bite raisers, without dislodgement during treatment, and ease of removal after treatment. The GI band cement is then added incrementally on the occlusal surfaces of the upper molars until 2 to 3 mm bite opening at the anterior teeth.  243

244 PA RT V I I     Management of Multidisciplinary and Complex Problems

Extrusion of Anterior Teeth to Close Anterior Openbite After placing the bite raisers, intermaxillary vertical elastics are then applied between the upper and lower anterior teeth. Patients are instructed to wear the intermaxillary

vertical elastics 14 to 20 hours per day, and arranged to return to the clinic on a monthly basis. Increment of GI band cement is added on the bite raisers to keep the bite opened 2 to 3 mm, at each monthly visit, so that the mandible rotates backward incrementally to the planned position or facial profile. 

A •

Fig. 16.1 The clinical procedure and case report of bimaxillary extrusion without TADs for backward rotation of mandible and redirecting the mandibular growth in a 13-year-old female client with Class III malocclusion. (A) The pretreatment extraoral, cone beam computed tomography (CBCT) images, and intraoral photographs revealed inadequate upper incisor show, excessive lower incisor display, maxillary hypoplasia, mandibular prognathism, and anterior crossbite; (Continued on next page)

CHAPTER 16  Orthognathic Camouflage With TADs for Improving Facial Profile in Class III Malocclusion

Extrusion of Posterior Teeth After the mandible has incrementally backward rotated to the planned position or facial profile and the upper and lower anterior teeth have been brought into occlusion, the bite raisers are removed. Intermaxillary posterior vertical elastics, together with TPA lateral expansion,

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are then applied to extrude the upper molars, without palatal tipping and decreasing maxillary intermolar width. After the upper and lower posterior teeth have occluded, a continuous maxillary archwire is then placed to replace the segmental archwires in the maxillary dentition. 

B

C • Fig. 16.1, cont’d  (B) The anterior crossbite was first corrected by maxillary orthopedic protraction through

7-week of Alternate Rapid Maxillary Expansions and Constriction (Alt-RAMEC) with a double-hinged expander and then a pair of intraoral protraction springs for 3 months. The expander was maintained for another 3 months after the maxillary protraction; (C) The overall skeletal superimposition on cranial base (pretreatment: silver color, postprotraction: green color) revealed the maxilla was protracted 3.0 mm, and the mandible was displaced downward 4.0 mm and backward 2.0 mm. (Continued on next page)

D

E

F • Fig. 16.1, cont’d  (D) Bite raisers were placed incrementally on the upper posterior teeth at each appointment

to open the bite 2 mm at the anterior teeth and to redirect the mandible downward and backward, and anterior vertical elastics were applied for bimaxillary extrusion of the anterior teeth and premolars after the upper and lower dentitions were aligned; (E) The bite raisers were removed and posterior vertical elastics were applied for extruding the posterior teeth, after 4 months of redirecting the mandibular growth; (F) The posterior teeth of both upper and lower dentitions were brought into occlusion after 5 months of posterior vertical elastics; (Continued on next page)

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G • Fig. 16.1, cont’d  (G) The posttreatment extraoral, CBCT images, and intraoral photos at the age of 15

years revealed a full smile arc and good amount of upper incisor show, without excessive lower incisor display, and a Class I facial profile; (Continued on next page)

248 PA RT V I I     Management of Multidisciplinary and Complex Problems

H

I • Fig. 16.1, cont’d  (H) The overall skeletal superimposition on cranial base (postprotraction: green color,

posttreatment: red color) revealed the maxilla remained stable, the maxillary posterior teeth were extruded 5.0 to 6.0 mm, the maxillary anterior teeth were extruded 2.0 to 3.0 mm, and the mandible was further redirected downward 5.0 mm and backward 3.0 mm. (I) The 1-year posttreatment extraoral and intraoral photos at the age of 16 years revealed stable clinical results, without obvious changes of facial profile and occlusion.

CHAPTER 16  Orthognathic Camouflage With TADs for Improving Facial Profile in Class III Malocclusion

A

B

C

D •

Fig. 16.2  The overall effects of maxillary protraction and redirection of mandibular growth of the case reported in Fig. 16.1. (A) The overall skeletal superimposition on cranial base (pretreatment: silver color, posttreatment: red color) revealed the maxilla was protracted 3.0 mm, and the mandible was redirected and grew downward 9.0 mm and backward 5.0 mm, rather than downward and forward; (B) The overall soft tissue superimposition based on overall skeletal superimposition on cranial base revealed the soft tissue at the midface and paranasal area was 1.5 mm fuller, and the chin projection reduced 5.0 mm backward and 8.0 mm downward; (C) The cranial base superimposition without mandible revealed the maxillary was protracted 3.0 mm, the maxillary molars were extruded 5.0 to 6.0 mm, and the maxillary anterior teeth were extruded 3.0 mm; (D) The mandibular superimposition illustrated the lower dentition was extruded 5.0 to 6.0 mm, and the mandibular condyles grew 4.0 mm.

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Single-Dentition Extrusion With TADs in Mandible This is a technique of orthodontic backward rotation of mandible with bite raisers, TADs in mandible, and vertical elastics. The strategy is to achieve backward rotation of mandible, without extruding lower anterior teeth, by using TADs in the mandible (Figs. 16.3 and 16.4).

Insertion of TADs The preparation procedure of this technique is the same as the bimaxillary extrusion without TADs. To rotate the mandible without extruding the lower dentition, TADs are placed in the anterior of mandible. The TADs could be inserted interdentally between mandibular canine and first premolar on both sides. 

A • Fig. 16.3  The clinical procedure and case report of single-dentition extrusion with TADs in mandible for backward rotation of mandible and redirecting mandibular growth in a 14-year 3-month-old male client with Class III malocclusion and bilateral cleft lip and palate. (A) The pretreatment extraoral, cone beam computed tomography (CBCT) images, and intraoral photographs revealed depressed midface and paranasal area, excessive chin throat length, maxillary hypoplasia, mandibular prognathism, and anterior crossbite;

(Continued on next page)

CHAPTER 16  Orthognathic Camouflage With TADs for Improving Facial Profile in Class III Malocclusion

B

C •

Fig. 16.3, cont’d (B) The anterior crossbite was first corrected by maxillary orthopedic protraction through 7-week Alternate Rapid Maxillary Expansions and Constriction (Alt-RAMEC) with a double-hinged expander and then a pair of intraoral protraction springs for 3 months. The expander was maintained for another 3 months after the maxillary protraction; (C) The overall skeletal superimposition on cranial base (pretreatment: silver color, postprotraction: green color) revealed the maxilla was protracted 3.0 mm, and the mandible was displaced downward 7.0 mm and backward 1.5 mm; (Continued on next page)

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D

E

F • Fig. 16.3, cont’d  (D) The TADs were inserted between the lower canine and first premolar at both sides,

bite raisers were placed incrementally on the upper posterior teeth at each appointment to open the bite 2 mm at the anterior teeth, and vertical elastics were applied between the lower TADs and upper dentition to extrude the upper dentition and redirect mandibular growth; (E) The bite 6 months after redirecting mandibular growth; (F) The bite raisers were removed and posterior vertical elastics were applied for extruding the posterior teeth for 15 months; (Continued on next page)

CHAPTER 16  Orthognathic Camouflage With TADs for Improving Facial Profile in Class III Malocclusion

G • Fig. 16.3, cont’d  (G) The posttreatment extraoral, CBCT images, and intraoral photos at the age of 16 years and 9 months revealed a better smile arc, and upper incisor show and improvement of facial profile;

(Continued on next page)

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H • Fig. 16.3, cont’d  (H) The overall skeletal superimposition on cranial base (postprotraction: green color, posttreatment: red color) revealed the maxilla grew 1.0 mm forward further, although there were anterior teeth dental relapse. The maxillary dentition was extruded 4.0 to 5.0 mm at the anterior and 6.0 to 7.0 mm at the posterior, and the mandible was further redirected downward 4.0 mm and backward 1.0 mm.

Placement of Bite Raisers and Extrusion of Upper Anterior Teeth The placement of the bite raisers is the same as the procedure of bimaxillary extrusion without TADs. After insertion of the TADs in mandible and placement of bite raisers on the occlusal surfaces of maxillary posterior teeth, intermaxillary vertical elastics are then applied between the upper anterior teeth and the lower TADs for extruding the upper dentition. 

Extrusion of Posterior Teeth This procedure is the same as the extrusion of posterior teeth in procedure of bimaxillary extrusion without TADs. 

Single-Dentition Extrusion With TADs in Maxilla This is a technique of orthodontic backward rotation of mandible, with TADs in maxilla, without bite raisers and vertical elastics. The strategy is to achieve backward rotation of mandible, without extruding lower anterior teeth by using TADs and extruding springs in the maxilla (Figs. 16.5 and 16.6).

Insertion of TADs To rotate the mandible without extruding the lower dentition and without bite raisers, TADs are placed in the buccal

side of maxilla. The TADs could be inserted interdentally between the maxillary canine and first premolar, between the premolars, or between the first molar and premolar on both sides in extraction cases. After insertion of the TADs, a pair of extruding springs (0.019 × 0.025 titanium molybdenum alloy [TMA]) is placed in the TADs, for extruding the entire maxillary dentition. The extruding spring is composed of two arms. One arm is for the extrusion of maxillary anterior, and it is hooked on the main archwire, between the central incisors, to avoid occlusal cant caused by unbalancing force, from each side of the extruding springs. The other arm is for the extrusion of maxillary posterior teeth, and it is hooked on the main archwire between the first and second maxillary molars. The TADs insertion sites are better symmetrically at the same position, on each side, so that the extruding springs are equal in length and force to avoid causing occlusal cant. A removable and adjustable TPA (0.032 TMA) should be used to avoid palatal tipping of posterior teeth during molar extrusion. Buccal crown torque and lateral expansion are added on the TPA. 

Maxillary Vertical Development in Class III Patients Either bimaxillary or single-dentition extrusion extrudes maxillary dentition and also develops maxillary vertical height, which improves the smile and upper incisor show

A

B

C

D •

Fig. 16.4 The overall effects of maxillary protraction and redirection of mandibular growth with lower TADs of the case reported in Fig. 16.3. (A) The overall skeletal superimposition on cranial base (pretreatment: silver color, posttreatment: red color) revealed the maxilla was protracted and grew forward 4.0 mm, and the mandible was redirected and grew downward 11.0 mm and backward 2.5 mm, rather than downward and forward; (B) The overall soft tissue superimposition based on overall skeletal superimposition on cranial base revealed the soft tissue at the midface and paranasal area was 2.5 mm fuller, and the chin projection reduced 6.0 mm backward and 11.0 mm downward; (C) The cranial base superimposition without mandible revealed the maxillary was protracted and grew 4.0 mm forward, the maxillary posterior teeth were extruded 8.0 mm, and the maxillary anterior teeth were extruded 5.0 mm; (D) The mandibular superimposition illustrated the lower posterior teeth were extruded and erupted 5.0 to 6.0 mm, the lower anterior teeth were extruded and erupted 2.0 mm, and the mandibular condyles grew 8.0 mm on the right and 6.0 mm on the left.

256 PA RT V I I     Management of Multidisciplinary and Complex Problems

in patients with Class III malocclusion. Maxillary hypoplasia and/or mandibular prognathism are the most two common features in patients with Class III malocclusion. The maxillary hypoplasia includes sagittal and/or vertical deficiency. Unfortunately, the Class III orthodontic camouflage treatment usually focuses on the sagittal improvement of anterior crossbite,5–7 but seldom on the improvement of maxillary vertical deficiency.

Orthodontic extrusion or force eruption has been used successfully for implant site development in alveolar vertical bone height.19–21 Similarly, the extrusion of maxillary dentition could develop the maxillary alveolar vertical bone height and subsequently improve the maxillary incisors show and smile arc, backward rotate the mandible, reduce chin prominence, and shorten the chin throat length. 

A •

Fig. 16.5  The clinical procedure and case report of single-dentition extrusion with TADs in maxilla for backward rotation of mandible and orthognathic camouflage in a 27-year-old female with Class III malocclusion. (A) The pretreatment extraoral, cone beam computed tomography (CBCT) images, and intraoral photographs revealed excessive chin throat length, mandibular prognathism, inadequate upper incisors show, excessive lower incisors display, flat smile arc, and anterior cross bite; (Continued on next page)

CHAPTER 16  Orthognathic Camouflage With TADs for Improving Facial Profile in Class III Malocclusion

Comparisons and Indications of Bimaxillary Extrusion and Single-Dentition Extrusion The bimaxillary extrusion extrudes both the maxillary and mandibular dentitions. On the other hand, the single-dentition with TADs in mandible or maxilla extrudes mostly maxillary dentition, but not the mandibular dentition. Bimaxillary extrusion has been reported to be

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more efficient and effective than single-dentition extrusion in rotating the mandible downward and backward in growing Class III patients.13 It has more mandibular backward rotation and orthognathic camouflage than the single-dentition extrusion. Single-dentition extrusion might spend more time in rotating the mandible clockwise to the same extent the bimaxillary extrusion does. Bimaxillary extrusion extrudes lower incisors and may unfavorably increase lower incisor show, especially in adult

B

C •

Fig. 16.5, cont’d  (B) The anterior crossbite was first improved by alignment and leveling of the upper and lower dentitions with bite raisers at the upper posterior teeth for jumping the bite. Then, TADs were inserted between the upper canine and first premolar at both sides; (C) pairs of extruding springs (0.019 × 0.025 TMA) were placed in the TADs for extruding upper dentition. The upper archwire was built in with anterior teeth labial torque, for avoiding palatal tipping during extrusion, and a transpalatal arch (TPA) was built in with lateral expansion and parallel molar torque for avoiding palatal tipping and decreasing buccal overjet during extrusion; (Continued on next page)

D

E • Fig. 16.5, cont’d  (D) The extruding springs and the TPA lateral expansion were applied for 8 months; (E)

The posttreatment extraoral, CBCT images, and intraoral photos revealed a better smile arc, upper incisor show, and improvement of facial profile.

CHAPTER 16  Orthognathic Camouflage With TADs for Improving Facial Profile in Class III Malocclusion

A

B

C

D • Fig. 16.6  The overall effects of orthognathic camouflage of the case reported in Fig. 16.5. (A) The overall skeletal superimposition on cranial base (pretreatment: silver color, posttreatment: red color) revealed the maxillary dentition was extruded 4.0 to 5.0 mm, and the mandible was rotated downward 5.0 mm and backward 4.0 mm; (B) The overall soft tissue superimposition based on overall skeletal superimposition on cranial base revealed the chin projection reduced 3.0 mm backward and 3.0 mm downward. The chin throat length decreased 3.0 mm; (C) The cranial base superimposition without mandible revealed the maxillary dentition was extruded 4.0 to 5.0 mm; (D) The mandibular superimposition illustrated the lower second molars were intruded 1.5 mm, lower premolars were extruded 1.5 mm, and the lower anterior teeth were intruded 1.5 mm. The lower curve spee was leveled.

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patients. Interestingly, we have observed clinically that the lower incisor show remained similar or even was less in growing patients treated with bimaxillary extrusion (see Fig. 16.1). This could be caused by the growth of soft tissue compensating for the extrusion of lower incisors. Thus, due to the mandibular growth, growing patients are better treated by bimaxillary extrusion. For the adult patients with excessive lower incisor show, bimaxillary extrusion could be contraindicated. On the other hand, bite raisers open the bite but also interfere with eating. This might be not a big problem for growing patient but could be a problem for adult patients. The single-dentition extrusion with TADs in maxilla would be friendlier for adult patients. Backward rotation of mandible also increases anterior facial height and might lead to lip incompetence. Therefore backward rotation of mandible should be stopped when lip incompetence is developing. Orthodontic backward rotation of mandible is indicated in Class III patients with short face, low angle, maxillary vertical deficiency, or overclosure, and it might not be indicated in Class III patients with long face, high angle, openbite, or lip incompetence. Class III patients with lip incompetence caused by dentoalveolar protrusion could still be candidates for extraction therapy. 

The Stability of Orthodontic Extrusion Although the long-term stability of orthodontic extrusion has yet to be well revealed, the 1 to 3 years posttreatment results were reported stable in some case reports.22–24 In contrast, the stability of orthodontic intrusion has been documented and the 3 to 4 years posttreatment relapse of orthodontic intrusion of posterior teeth was 13.37% to 22.88%.25,26 The long-term stability of orthodontic extrusion could be similar to that of orthodontic intrusion, and overcorrection is commended for the backward rotation of mandible in patients with Class III malocclusion.

References 1. Patel PK, Novia MV: The surgical tools: the LeFort I, bilateral sagittal split osteotomy of the mandible, and the osseous genioplasty, Clin Plast Surg 34:447–475, 2007. 2. Drommer RB: The history of the “Le Fort I osteotomy”, J Maxillofac Surg 14:119–122, 1986. 3. Epker BN: Modifications in the sagittal osteotomy of the mandible, J Oral Surg 35:157–159, 1977. 4. Chen YR, Yeow VK: Multiple-segment osteotomy in maxillofacial surgery, Plast Reconstr Surg 104:381, 1999. 5. Baik HS: Limitations in orthopedic and camouflage treatment for Class III malocclusion, Semin Orthod 13:158–174, 2007. 6. Burns NR, Musich DR, Martin C, Razmus T, Gunel E, Ngan P: Class III camouflage treatment: what are the limits? Am J Orthod Dentofacial Orthop 137: 9.e1-9.e13, 2010.

7. Tekale PD, Vakil KK, Parhad SM: Orthodontic camouflage in skeletal class III malocclusion: a contemporary review, J Orofac Res 4:98–102, 2014. 8. Ning F, Duan YZ: Camouflage treatment in adult skeletal Class III cases by extraction of two lower premolars, Korean J Orthod 40:349–357, 2010. 9. Yanagita T, Kuroda S, Takano-Yamamoto T, Yamashiro T: Class III malocclusion with complex problems of lateral open bite and severe crowding successfully treated with miniscrew anchorage and lingual orthodontic brackets, Am J Orthod Dentofacial Orthop 139:679–689, 2011. 10. He S, Gao J, Wamalwa P, Wang Y, Zou S, Chen S: Camouflage treatment of skeletal Class III malocclusion with multiloop edgewise arch wire and modified Class III elastics by maxillary mini-implant anchorage, Angle Orthod 83:630–640, 2013. 11. Nakamura M, Kawanabe N, Kataoka T, Murakami T, Yamashiro T, Kamioka H: Comparative evaluation of treatment outcomes between temporary anchorage devices and Class III elastics in Class III malocclusions, Am J Orthod Dentofacial Orthop 151:1116–1124, 2017. 12. Modarai F, Donaldson JC, Naini FB: The influence of lower lip position on the perceived attractiveness of chin prominence, Angle Orthod 83:795–800, 2013. 13. Liou EJ, Wang YC: Orthodontic clockwise rotation of maxillomandibular complex for improving facial pro le in late teenagers with Class III malocclusion: a preliminary report, APOS Trends in Orthod 8:3–9, 2018. 14. Tsai IM, Lin CH, Wang YC: Correction of skeletal Class III malocclusion with clockwise rotation of the maxillomandibular complex, Am J Orthod Dentofacial Orthop 141:219–227, 2012. 15. Villegas C, Janakiraman N, Uribe F, Nanda R: Rotation of the maxillomandibular complex to enhance esthetics using a “surgery first” approach, J Clin Orthod 46:85–91, 2012. quiz 123. 16. Choi JWMD, Park YJ, Lee CY: Posterior pharyngeal airway in clockwise rotation of maxillomandibular complex using surgery-first orthognathic approach, Plast Reconst Surg Glob Open 3(8):e485, 2015. 17. Tanaka E, Yamano E, Inubushi T, Kuroda S: Management of acquired open bite associated with temporomandibular joint osteoarthritis using miniscrew anchorage, Korean J Orthod 42:144–154, 2012. 18. Alsafadi AS, Alabdullah MM, Saltaji H, Abdo A, Youssef M: Effect of molar intrusion with temporary anchorage devices in patients with anterior open bite: a systematic review, Prog Orthod 179-136, 2016. 19. Salama H, Salama M: The role of orthodontic extrusive remodeling in the enhancement of soft and hard tissue profiles before implant placement: a systematic approach to the management of extraction site defects, Int J Periodontics Restorative Dent 13:312– 333, 1993. 20. Rokn AR, Saffarpour A, Sadrimanesh R, et al.: Implant site development by orthodontic forced eruption of nontreatable teeth: a case report, Open Dent J 6:99–104, 2012. 21. Kwon EY, Lee JY, Choi J: Effect of slow forced eruption on the vertical levels of the interproximal bone and papilla and the width of the alveolar ridge, Korean J Orthod 46:379–385, 2016.

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22. Atsawasuwan P, Hohlt W, Evans CA: Nonsurgical approach to Class I open-bite malocclusion with extrusion mechanics: a 3-year retention case report, Am J Orthod Dentofacial Orthop 147:499–508, 2015. 23. Küçükkeleş N, Acar A, Demirkaya AA, Evrenol B, Enacar A: Cephalometric evaluation of open bite treatment with NiTi arch wires and anterior elastics, Am J Orthod Dentofacial Orthop 116:555–562, 1999. 24. Lo FM, Shapiro PA: Effect of presurgical incisor extrusion on stability of anterior open bite malocclusion treated with orthognathic surgery, Int J Adult Orthodon Orthognath Surg 13:23–34, 1998.

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25. Baek MS, Choi YJ, Yu HS, Lee KJ, Kwak J, Park YC: Long-term stability of anterior open-bite treatment by intrusion of maxillary posterior teeth, Am J Orthod Dentofacial Orthop 138:396, e1-9, 2010; discussion 396-398. 26. Marzouk ES, Kassem HE: Evaluation of long-term stability of skeletal anterior open bite correction in adults treated with maxillary posterior segment intrusion using zygomatic miniplates, Am J Orthod Dentofacial Orthop 150:78–88, 2016.

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Management of Multidisciplinary Patients With TADs FLAVIO URIBE, RAVINDRA NANDA

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ultidisciplinary treatment encompasses the care of a patient where two or more specialties overlap to work synergistically, to obtain the best outcome. In orthodontics, this interaction is often found with the restorative dentist or prosthodontist. The problems usually addressed as a team include the preprosthetic work, for the placement of dental implants, or other dental restorations. Another common interaction is also evidenced in patients undergoing orthognathic surgery, where the orthodontist and oral surgeon work as a team in the treatment of patients with dentofacial deformity. Adults seeking orthodontic treatment are the patient demographic that more often require interdisciplinary care. Furthermore, the number of adult patients in orthodontic treatment has increased in the United States in recent years.1 Often these patients present with a whole range of occlusal problems, which many of them stem from the missing teeth. The deleterious occlusal effects of missing teeth may compound with an already present malocclusion, which adds to the complexity of treatment. A significant malocclusion, with few anchor teeth for demanding orthodontic movements, require careful treatment planning and often the aid of skeletal anchorage units.

Temporary Anchorage Devices (TADs) for Space Development for Implant in Congenitally Missing Lateral Incisor The most common type of multidisciplinary treatment in orthodontics involves the space appropriation required for prosthetic work to be performed, after orthodontics. Ridge space development for patients, congenitally missing lateral incisors, is one such clinical situation that may require the use of skeletal anchorage, if a nonextraction treatment approach is planned.

Case Report One Fig. 17.1 shows a 33-year-old female patient congenitally missing the permanent maxillary left lateral incisor.

The primary left lateral incisor was supraerupted and was squeezed out of the arch, leaving only approximately 3 mm of space between the left permanent central incisor and the canine. With time, the maxillary primary lateral incisor had become symptomatic, as evidenced by a fistula in the labial mucosa, which required to take action. Only minimal space was available for the placement of an implant in the lateral incisor site, after the eventual extraction of the primary lateral incisor. A canine substitution option required the buccal segment to be protracted from an end-on Class II relationship to a fullcusp Class II occlusion. The patient was adamant of getting an endosseous dental implant placed on the lateral incisor site, which required the distalization of the buccal segment for the development of adequate space for this missing tooth. The patient was opposed to the extraction of the left first premolar to obtain the required space for the lateral incisor. To distalize the left buccal segment, including the canine, two 1.8 × 8 mm IMTEC Ortho mini-implants (3M Unitek, Ardmore, Okla) were placed in the palate, at the level of the second premolar. An alginate impression was taken of the maxilla, and two analogue mini-implants were placed on the impression, and stone was poured to obtain a working model. Two O-caps (IMTEC Ortho, 3M Unitek, Ardmore, Okla) were used as framework to fabricate a distalization appliance, consisting of a tracking bar parallel to the left buccal segment, at a height close to the furcation of the first molar. A band with a lingual 0.032-inch Burstone bracket (Ormco, Glendora, Calif ) with a hinge cap was cemented on the first molars. From the lingual bracket, an extension arm with a head gear tube engaged the tracking bar of the appliance. An open coil spring along the tracking bar was placed to drive the first molar distal. Once distalization was achieved, natural drift of the premolars was monitored until labial conventional orthodontic appliances were added to detail the occlusion and achieve the proper dimensions for the endosseous dental implant in the lateral incisor site.  263

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• Fig. 17.1  TAD-supported maxillary distalization for implant site development. (A) Pretreatment extra-

oral (A–C) and intraoral (D–F) photographs. (G) Two palatal IMTEC Ortho mini-implants supporting a framework with tracking arms, extending posteriorly to the first molars. Space opening mesial to the left maxillary first molar after distalization force delivered directly form the TADs. (H) Class I molar achieved on the left side. (I) Space developed for a lateral incisor dental implant after the extraction of the primary tooth. (J) Class I canine achieved with distalization. (K–N) Final intraoral photographs, after final restoration with the endosseous dental implant. (O) Smile photograph depicting the excellent esthetic result. (P) Close-up view of the lateral incisor implant crown.

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TADs for Preprosthetic Space Appropriation Another situation where TADs are important, in multidisciplinary treatment, is in the space appropriation for esthetic prosthetic restorations in the anterior maxillary segment.

Case Report Two Fig. 17.2 displays a patient who was seeking better smile esthetics. The maxillary incisors were worn on the incisal edges, the maxillary dental midline was significantly deviated to the right, and the patient displayed a Class II molar occlusion on the left side, with a significant overbite. On the lower arch, the patient had only two mandibular incisors. The plan consisted of centering the maxillary midline, overbite correction, and space appropriation for maxillary anterior veneers, which was to be obtained through the correction of the Class II canine and molar relationship on the left side. In the lower arch, space was to be developed mesial to the right canine, for one single dental implant. To achieve the objectives in the maxilla, an infrazygomatic (IZ) Lomas mini-implant (Mondeal Medical Systems, Donau, Germany) was placed on the left side and distalization of the maxillary left buccal segment was achieved. At the end of the orthodontic and prosthodontic treatments, Class I occlusion and matched dental and facial midlines were observed. 

Endosseous Dental Implants for Anchorage in Patients With Missing Posterior Teeth Skeletal anchorage for orthodontic movement in multidisciplinary patients can also be achieved through the placement of endosseous dental implants, during orthodontic treatment. This is a cost-effective use of skeletal anchorage, as the dental implant would serve a dual purpose, for orthodontic anchorage and restoration of an edentulous site.

Case Report Three Fig. 17.3 displays a 66-year-old male with a heavily restored dentition, a Class II malocclusion, and significant overjet and overbite. The treatment plan for this patient included the correction of the overbite, using an intrusion arch in the mandibular dentition. The overjet was to be corrected through the extractions of the maxillary right first premolar, which had a periapical lesion and the left second premolar that had a coronal cusp facture. The maxillary left first molar had a root fracture, making it unrestorable, requiring also the extraction of this tooth. An endosseous dental implant was to be placed, once the site healed, after the extraction. This implant was to be used during orthodontic treatment to maximize the retraction of the canine, without any mesial movement of the posterior segment or anchorage loss. 

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• Fig. 17.2  Preprosthetic space appropriation and midline correction with unilateral infrazygomatic (IZ) temporary anchorage device (TAD). Pretreatment extraoral (A–C) and intraoral photographs (D–H). (I–K), IZ TAD on the left side to distalize the buccal segment and center the maxillary dental midline.

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N • Fig. 17.2, cont’d  (L) Improvement on the maxillary dental midline in relation to the facial midline. (M)

Final smiling photograph, with maxillary veneers. (N) Intraoral photo of the final maxillary and mandibular restorations.

Ridge Mini-implants for Orthodontic Anchorage Although endosseous dental implants provide a dual advantage when placed (anchorage during orthodontic treatment and restorative prosthetic solution at the end of treatment),2,3 there are certain limitations and problems that may arise when placing dental implants, before or during the early phases of orthodontic treatment. Often the final predicted location of the endosseous dental implant after orthodontic treatment is not precise, requiring the restorative dentist to make adjustments to the restoration that may compromise the esthetics of the outcome. One option that still allows to draw skeletal anchorage from edentulous areas, without the rigor of perfect insertion location of the fixture, is the placement of miniimplants vertically into the alveolar ridge, mimicking the position of a conventional endosseous dental implant. These mini-implants can then be used for anchorage purposes and even replaced in other locations, as needed, during orthodontic treatment. In fact, this approach has the advantage of enabling the clinician to apply conventional orthodontic biomechanics while using skeletal anchorage

as the mini-implant is placed along the arch. A bracket is bonded to the attachment head of the mini-implant, after adding a temporary crown made out of flowable composite, thereby allowing the mini-implant to receive the main archwire through the bracket slot. The only limitation of this type of TAD placement is that it does not allow an easy approach for significant intrusion of the adjacent teeth, when using direct anchorage. However, by means of cantilever arms, vertical forces can be delivered to the anterior teeth. Overall, the main role of this mini-implant is the aid in anchorage in the anteroposterior dimension. There are various advantages in these ridge mini-implants. Firstly, this mini-implant is easy to place, as there is typically ample room for insertion. Secondly, it is easy to apply conventional biomechanics, as it can be added to the archwire to deliver the necessary forces. Thirdly, compared to endosseous dental implants, the insertion site can be changed, depending on the specific needs during treatment. In other words, there is versatility also for changes in the treatment plan, based on the progress of treatment. Finally, it allows to deliver a push-type force mechanism, a force delivery type that is not typically delivered directly from mini-implants, where pull-type mechanics is the norm.

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J • Fig. 17.3  Endosseous dental implant for orthodontic anchorage. Pretreatment extraoral (A–C) and intra-

oral photographs (D–H). Lateral cephalogram (I) and panoramic radiograph (J). (K–M) Segmental mandibular incisor intrusion. (N–Q) Extraction of maxillary right first premolar and left second premolar for orthodontic reasons. Endosseous dental implant placement on the maxillary left molar region. This tooth required extraction because of root fracture. (R–U) Maxillary canine retraction from endosseous dental implant on the left side for maximum anchorage. Posttreatment intraoral (V–Y) and extraoral (Z–ZB) photographs. Posttreatment lateral cephalogram (ZC) and panoramic (ZD) radiographs. (ZE) Final dental implant restoration on the left maxillary first molar.

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The specific technique for ridge mini-implant placement is as follows: 1. A mini-implant with a rectangular or square attachment head with enough retention areas, such as bracket wings, is preferred, as composite material will mechanically interlock. The Lomas Quattro mini-implant (Mondeal

Medical Systems, Donau, Germany) complies with this characteristic. Typically, the dimension used is a 2 × 9-mm or 2.3 × 9-mm mini-implants. 2. The mini-implant is inserted with a contraangle driver on the ridge. A pilot hole is placed if the alveolar ridge morphology is that of a knife edge.

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3. Once the mini-implant is placed, it is important to visualize the location of the attachment head, as it should be in close proximity to the line connecting the labial surfaces of the adjacent teeth. 4. Occlusogingivally, the attachment head should not be in contact with the teeth in the opposing arch and should be close to the height of the bracket level of the adjacent teeth. 5. Flowable composite is applied around the attachment head, and a bracket is bonded trying to allow a passive wire engagement in occlusogingival and buccolingual direction, in relation to the adjacent teeth. 6. A wire is placed to start tooth movement.

7. If failure of the ridge mini-implant is observed, two miniimplants are placed adjacent to each other and splinted, with flowable composite to increase stability. Another one of the advantages of placing mini-implants in the ridge is observed in patients with large edentulous spans, where the terminal tooth needs to be orthodontically moved.

Case Report Four Fig. 17.4 shows a 29-year-old female patient with multiple missing teeth, especially in the lower arch. A large edentulous span is observed from the right first premolar through

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J • Fig. 17.4  Anchorage derived from ridge mini-implants. Pretreatment extraoral (A–C) and intraoral pho-

tographs (D–H). Pretreatment lateral cephalogram (I) and full mouth periapical radiographs (J). (K–O) Progress after placement of two ridge mini-implants in the mandibular molar region bilaterally. (P–T) Progress showing the protraction of mandibular molars and midline correction, with anchorage derived from the ridge mini-implants. (U–Y) Posttreatment intraoral photographs. (Z) Lower thermoplastic retainer, with pontics, showing the adequate spacing for dental implants on the mandibular arch. Note that the right third molar erupted after protraction of the second molar. (ZA–ZC) Posttreatment extraoral photographs. Posttreatment lateral cephalogram (ZD) and panoramic (ZE) radiographs.

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the right second molar. The right mandibular third molar was impacted distal to the second molar. The plan for this patient included the extraction of the maxillary right first premolar to retract the incisors, reducing the proclination of these teeth and the overjet, and to protract the lower right second molar to reduce the edentulous space to a single endosseous dental implant. On the mandibular left side, the buccal segment was to be protracted to match the maxillary midline while maintaining the edentulous sites.

Two ridge 2 × 9-mm Lomas mini-implants were placed mesial to both mandibular second molars. These miniimplants allowed for better stiffness of the archwire in the edentulous spans as the interbracket distance was reduced. The result was better control of the adjacent teeth to be moved. On the right side, the first molar was moved anteriorly, allowing for the eruption of the third molar into occlusion and reduction of the edentulous span to the space of a single restoration with an endosseous dental implant. On

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the left side, the ridge mini-implant was used to correct the mandibular yaw. The left buccal segment was protracted to correct the lower midline deviation and the mesiodistal width of the edentulous sites was maintained, preserving the space for two endosseous dental implants. 

TADs in Patients With Compromised Maxillary Incisors Another specific clinical situation, where mini-implants are appropriate in multidisciplinary care, is evident when some

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of the teeth in the arch have poor prognosis and anchorage cannot be drawn from them. Fig. 17.5 illustrates a 24-yearold male patient with significant root resorption of the maxillary central incisors and congenitally missing the right maxillary incisor. The buccal occlusion was Class I bilaterally and the maxillary incisor anteroposterior position and lip support was normal. The treatment plan for this patient included either the substitution of the canine for the lateral incisor, and the replacement of the two significantly resorbed incisors, with two endosseous dental implants placed next to each other; or the placement of two dental implants in the sites of the right lateral incisor, and left central incisor,

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• Fig. 17.5  Infrazygomatic temporary anchorage device (TAD) for anchorage to retract a canine on a patient

with severely resorbed maxillary central incisors. (A–D) Pretreatment intraoral photographs and panoramic radiograph (E). (F–H) Progress of treatment showing the distalization of the maxillary right canine, bypassing the severely resorbed incisors. (I–L) Progress showing space development for the congenitally missing right lateral incisor. (M–P) Bonding of central incisors to achieve proper anterior spacing for an implant supported bridge, from the right lateral to the left central incisor, after distalization of the canine.

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and a pontic on the right central incisor supported by the two implants. This last option was selected as the restorative prosthodontist believed that the soft tissue, especially the papillary heights, would have a better esthetic outcome if the implants were separated by a pontic. To achieve this objective, it was required to maintain perfect anchorage on the right side while retracting the canine. This was achieved by placing a 2 × 9-mm Lomas IZ mini-implant (Mondeal Medical Systems, Donau, Germany) from which a retraction force was applied. A 0.019 × 0.025-inch stainless steel archwire bypassing the anterior teeth was placed and a bracket with an extension arm bonded to the canine. The canine was retracted to a Class I canine relationship and a then the anterior teeth were bonded for proper space appropriation and placement of a temporary esthetic pontic. 

Skeletal Anchorage in Orthognathic Surgery Another example where skeletal anchorage is useful in multidisciplinary treatment occurs in orthognathic surgery. Of recent, the surgery first approach has become a popular treatment method in orthognathic surgery, for patients with dentofacial deformity, with some advantages over the conventional three-stage approach.4,5 Some of these patients may present with congenitally missing lateral incisors that could be treated with canine substitution, as a presurgical phase, while the patient is still growing. The protraction of the posterior segment into the site of the missing lateral incisor can be achieved in a very inconspicuous manner, if addressed from the palate.

Case Report Five Fig. 17.6 illustrates a 17-year-old male patient with a moderately concave profile, midface deficiency, and a Class III malocclusion with anterior and posterior crossbites. The patient was congenitally missing the maxillary left lateral incisor. Based on his age, it was decided to monitor his growth through serial cephalograms to properly determine if the skeletal growth had ceased. During this time, it was prescribed for the patient to receive a very limited presurgical orthodontic phase consisting of a protraction appliance to the left buccal segment for the canine substitution. Two maxillary 1.8 × 8-mm IMTEC Ortho mini-implants (3M Unitek, Ardmore, Okla) were placed on both sides of the palate, slightly lateral to the midpalatal raphe. An appliance that connected two O-caps (IMTEC Ortho, 3M Unitek, Ardmore, Okla) was fabricated, which consisted of a tracking bar that extended parallel to the left buccal segment. A molar band was attached to the tracking bar, through an extension arm from the lingual side, with a soldered headgear tube that engaged the tracking bar as described in the patient in Fig. 17.1. A coil spring, delivering 200-g of force, was used from the extension arm to a hook in the appliance to close the space mesial to the premolars. After 7 months of molar protraction and with the determination of skeletal growth completion, the patient was bonded with full labial orthodontic appliances for a modified surgery first approach. With this protocol, no alignment or leveling of the arches was done before surgery. Passive wires were inserted before the surgical procedure. Two weeks after surgery, the orthodontic treatment was started to align and level the arches and refine the occlusal result. The postsurgical orthodontic treatment lasted for 16 months with very good esthetic and occlusal results. 

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Fig. 17.6  Protraction of the buccal segment into congenitally missing lateral incisor from palatal temporary anchorage devices (TADs) before orthognathic surgery. Pretreatment extraoral (A–C) and intraoral photographs (D–G). Pretreatment lateral cephalogram (H) and panoramic (I) radiographs. (J) Left molar protraction device from two palatal IMTEC Ortho mini-implants. (K–N) Progress of molar protraction with all anterior spaces closed. Patient with brackets bonded and ready for a modified surgery first approach. Postsurgical extraoral (O–Q) and intraoral (R–T) photographs. Posttreatment extraoral (U–W) and intraoral (X–ZA) photographs. (ZB) Posttreatment lateral cephalogram.

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Mini-implants in Vertical Alveolar Ridge Development Finally, skeletal anchorage is also a good tool for the vertical alveolar bone development, in patients with compromised periodontal support and esthetics in the anterior region. Vertical alveolar bone development can be performed in a localized manner, with anchorage derived from a mini-implant.6

Case Report Six Fig. 17.7 shows a 53-year-old female patient with reduced periodontal attachment in the anterior maxillary region. Specifically, the right lateral and central incisors were affected by bone loss and had supraerutped, resulting in unesthetic consequences that included recession and significant open gingival embrasures in this region. The patient wanted to address her smile esthetics in the anterior region of the maxilla. A treatment plan was prescribed that included the forced eruption of both the right central and lateral incisors, until adequate vertical alveolar bone height was obtained. This vertical alveolar bone displacement also resulted in better gingival architecture, before the placement of an endosseous dental implant. Because of limited finances, a single implant in the central incisor site was placed after the extraction of both right incisors. A cantilever ovate pontic from the central incisor implant was to be placed to mimic the gingival contours of the contralateral lateral incisor.

A 2 × 9-mm Lomas mini-implant (Mondeal Medical Systems, Donau, Germany), with a slot in the attachment head, was placed between the right incisors. Brackets were bonded to both incisors and connected with a 0.019 × 0.025-inch stainless steel wire segment, inserted in the slot of these brackets passively. A double tube, one in a vertical and the other in a horizonal direction, was welded to this archwire. Another 0.019 × 0.025-inch stainless steel archwire was inserted through the slot of the mini-implant and the vertical tube of the double tube. The wire was left long and bent on the gingival portion and a coil spring delivering an extrusion force was placed. The lower portion of the wire was cut to prevent any discomfort of the patient. The final esthetic result shows the significant smile esthetics enhancement through the coronal migration of the gingival margin levels, with the reduction of the open gingival embrasures. 

Conclusion Skeletal anchorage is a powerful aid in multidisciplinary treatment. Patients undergoing preprosthetic orthodontics and orthognathic surgery benefit from the use of miniimplants and miniplates. Multiple options for skeletal anchorage are available that include preprosthetic space appropriation, vertical alveolar ridge development, increased archwire stiffness in edentulous sites and protraction of segments, before orthognathic surgery.

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• Fig. 17.7  Vertical alveolar bone development from a mini-implant in the anterior maxillary region. (A) Smile photograph showing the affected anterior esthetics, with periodontal attachment loss. (B) Supraerupted maxillary right central and lateral incisors creating an unesthetic black triangle. (C) Panoramic radiograph showing the reduced vertical bone levels on the right maxillary incisors. (D–G) Progress of the eruption of the two right incisors from a temporary anchorage device (TAD) placed in the interradicular bone between these two teeth.

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Fig. 17.7, cont’d (H) Periapical radiograph showing the progress and vertical ridge development. (I) Retention wire to hold the vertical alveolar development. Note the favorable coronal migration of the soft tissue. Radiograph with wire retainer showing the vertical alveolar bone development (J) and after implant placement in the right central incisor site (K). (L) Smile photo with the temporary restoration of a cantilevered lateral incisor pontic from the central incisor implant. (M) Close up of the temporary restoration showing the drastic reduction in the black triangle and the natural interface between the pontic and the gingiva on the right lateral incisor site.

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Acknowledgments We would like to acknowledge all the residents and faculty who participated in the treatment of these cases.

References 1. Keim RG, Gottlieb EL, Vogels DS, Vogels PB: 2017 JCO Orthodontic practice study, J Clin Orthod 51:639–656, 2017. 2. Huang LH, Shotwell JL, Wang HL: Dental implants for orthodontic anchorage, Am J Orthod Dentofacial Orthop 127:713– 722, 2005.

3. Weber D, Handel S, Dunham D: Use of osseointegrated implants for orthodontic anchorage, J Clin Orthod 51:406–410, 2017. 4. Nagasaka H, Sugawara J, Kawamura H, Nanda R: “Surgery first” skeletal Class III correction using the skeletal anchorage System, J Clin Orthod 43:97–105, 2009. 5. Yang L, Xiao YD, Liang YJ, Wang X, Li JY, Liao GQ: Does the surgery-first approach produce better outcomes in orthognathic surgery? A systematic review and meta-analysis, J Oral Maxillofac Surg 75:2422–2429, 2017. 6. Fritz UB, Diedrich PR: Clinical suitability of titanium miniscrews for orthodontic anchorage. In: R N, editor: Temporary anchorage devices in orthodontics, St. Louis, Missouri, 2009, Elsevier, pp 287–294.

18

Second Molar Protraction and Third Molar Uprighting UN-BONG BAIK

Introduction Recently, with the help of temporary anchorage devices (TADs), substantial mandibular second molar protraction into the space created by a missing mandibular first molar (L-6) or retained deciduous mandibular second molar (L-E), without the succedaneous premolar, has become possible.1–9 When patients have impacted third molars, second molar protraction into the space of the missing tooth may promote the eruption of impacted third molars. Although the mechanics of second molar protraction may be challenging in some cases, most horizontally impacted third molars can be uprighted and serve as a substitute for implants or prostheses. The specific changes of impacted third molars following second molar protraction, such as spontaneous vertical eruption, horizontal movement, angular change, and others, are not yet known. Previous studies on the eruption or movement of third molars have mostly focused on their natural eruptive pattern, on patients who underwent extraction of premolars or second molars for orthodontic purposes.10–17 This chapter describes the movement of impacted third molars after second molar protraction.

Currently, 212 cases of second molar protraction into the space of a missing first molar or second premolar have been completed. Among them, there was agenesis of the third molars in 30 cases, 75 cases already had erupted third molars, and 107 had impacted third molars. This chapter describes the specific type of displacement observed in these 107 impacted third molars after second molar protraction. Various types of posterior occlusion may be observed when protracting mandibular molars. These types depend specifically on the site of the missing posterior teeth. Among them, the mandibular second molar can conform to one of the following four occlusal relationships. In this chapter, the term “Class I molar relationship” is used to describe the position of the second molars that have been moved into the first molar location. In addition, the term “U-6” signifies a missing maxillary first molar, “NE” means nonextraction, and “U-4” means upper bicuspid extraction. 1. U-NE (maxillary nonextraction treatment) + L-6: Class I molar relation (Fig. 18.1) 2. U-6 (missing maxillary first molar) + L-6: Class I molar relation (Fig. 18.2) 3. U-NE + L-E: Class III molar relation (Fig. 18.3) 4. U-4 (maxillary first premolar extraction treatment) + L-6: Class II molar relation (Fig. 18.4) 

• Fig. 18.1  U-NE + L-6: Final occlusion should be molar Class I relationship. (Canine relation: Class I) 283

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• Fig. 18.2  U-6 + L-6: Final occlusion should be molar Class I relationship. (Canine relation: Class I)

• Fig. 18.3  U-NE + L-E: Final occlusion should be molar Class III relationship. (Canine relation: Class I)

• Fig. 18.4  U-4 + L-6: Final occlusion should be molar Class II relationship. (Canine relation: Class I)

Third Molar Changes With Second Molar Protraction There have been many reports regarding the normal development or movement of the third molar after second molar extraction.10–17 Meanwhile, sufficient research has not been conducted on the eruption of an impacted third molar, after second molar protraction. The reason for this paucity in research has been that predictable molar protraction has been only available until recently, with the advent of TADs. The spontaneous movement of an impacted third molar is multidimensional. Therefore analysis should be performed

separately in each direction. Moreover, the studies on spontaneous angular changes and alveolar bone level are needed. Studies on the vertical eruption patterns of impacted mandibular third molars, after protraction of second molars, were performed and were recently published.18 This study was able to show that even the most severely impacted mandibular third molars may spontaneously erupt after second molar protraction, without the aid of any appliances. Even in such cases, where the root formation was slightly insufficient in the initial stage, the root eventually fully developed and the third molar erupted (Fig. 18.5). Furthermore, in adults whose third molar root was completely developed, proper eruption

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• Fig. 18.5  Spontaneous vertical eruption of an impacted third molar in a 17-year-old female. (A) Initial; (B)

Treatment progress; (C) Posttreatment; (D) 5 years and 8 months after debond. The missing mandibular left first molar space closed completely. The root was fully translated with no evidence of tipping. Although this was an adult and the third molar root was well developed, the third molar still erupted into the oral cavity, without the aid of any appliance.

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• Fig. 18.6  Spontaneous eruption and uprighting of the third molar on a 15-year-old male. (A) Radiograph

depicting extraction of left mandibular first molar. (B) Treatment progress showing space closure with eruption and uprighting of the third molar. (C) Posttreatment radiograph showing the missing first molar space closed completely; the impacted third molar followed spontaneously the second molar, without using any orthodontic appliances. (D) Three years and 6 months after debond.

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• Fig. 18.7  Unresponsive mandibular third molar to significant second molar protraction. (A) Pretreatment.

(B) Treatment progress of the protraction of the second molar. (C) Treatment progress with complete of space closure mesial to the second molar. (D) Treatment progress after the uprighting of the third molar. Surgical access and traction were necessary.

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Fig. 18.8 No change in third molar angulation after considerable second molar protraction. (A) Pretreatment; (B) Treatment progress during initial protraction of the second molar; (C) Space closure almost complete; (D) No distinct movement of the third molar observed although appropriate space was available.

followed in most of the cases. In this respect, age, gender, Nolla stage, and angle of the third molars did not show significant correlations with the vertical change of the impacted third molars, whereas, the depth of third molar impaction and available space showed significant correlations. In general, an impacted mandibular third molar follows the movement of the second molar during the protraction (Fig. 18.6). However, in some cases, the third molar does not follow the second molar (Fig. 18.7). Preliminary

studies reveal that the mesial movement of the third molar increases, as second molar protraction and Nolla stage of the third molar increase, and when the molar is located close to the occlusal plane. The spontaneous angular changes of an impacted mandibular third molar vary significantly. The angle remained constant (Fig. 18.8); uprighted without using any appliances (Fig. 18.9); while in some other cases, the third molar tipped more (Fig. 18.10). Preliminary findings evaluating the

286 PA RT V I I     Management of Multidisciplinary and Complex Problems

A

B

C

D

• Fig. 18.9  Spontaneous third molar uprighting on a 27-year-old male with poor prognosis of the left man-

dibular first molar. (A) Pretreatment showing complete horizontal impaction of the third molar. (B) Treatment progress immediately after extraction of the first molar. (C) Treatment progress during protraction of the second molar. (D) Considerable space closure achieved with partial uprighting and eruption of the third molar.

A

B

C

D

• Fig. 18.10  Spontaneous mesioangular tipping of the third molar on a 22-year-old female. (A) Third molar deeply impacted at pretreatment. (B) Treatment progress during protraction of the second molar. (C) Space closure almost complete and third molar erupting. (D) Posttreatment showing increased third molar mesioangular tip, as the second molar was protracted.

predictability in the changes suggest that: (1) older patients with more developed third molars tend to have these spontaneously upright; (2) available space for third molar eruption before and after second molar protraction is not associated with the angular change; (3) increased rate in the eruption process of third molars is associated with third molar uprighting; and (4) an increased rate of movement of the second molar may result in mesial tipping of the third molars. Alveolar bone changes of the second and third molars are of interest, since this approach is prolonged and orthodontic appliances are needed for longer periods of time. Our experience shows that the posttreatment alveolar bone level of fully impacted third molars are good; however, those of the second molars vary. In particular, the distal alveolar bone level shows a large variation. It is not known what factors influence these phenomena. Currently, we are conducting three-dimensional computed tomography scans studies to evaluate these specific changes. 

Cases of Horizontally Impacted Third Molars The following case reports illustrate the displacement changes observed on horizontally impacted third molars, resulting from second molar protraction. Partial uprighting with anterior movement and eruption of the crown allowed for placement of the third molars in proper occlusion.

Case One A 29-year-old female, with chief complaint of protrusion and crowding, presented for orthodontic treatment. Her skeletal pattern was Class II. The right mandibular first

molar had a periapical lesion for which the prognosis was deemed to be poor (Fig. 18.11). Treatment involved extraction of both maxillary first premolars and the right mandibular first molar. The space from the missing lower first molar was closed through second molar protraction. Significant molar protraction was necessary, which typically results in more side effects during the orthodontic movement.12 The mandibular third molar was horizontally impacted and had an antagonist (Fig. 18.12). An 0.018-inch slot and a straight wire appliance was used. In the upper arch, canine retraction was performed, while in the lower arch, second molar protraction was performed using sliding mechanics. A TAD was inserted in the lower right bicuspid area for protraction of the second molar (Fig. 18.13). After certain amount of canine retraction, brackets were bonded on the anterior maxillary teeth. The mandibular second molar was protracted considerably without tipping, and the impacted third molar erupted and partially uprighted, without orthodontic appliances (Fig. 18.14). During the space closure phase, long vertical hooks were attached for maximum retraction of the anterior teeth from the mini-implants. In the lower arch, midline correction was performed using the mini-implants for anchorage. A bracket was bonded to the impacted right third molar for root control (Fig. 18.15). The final occlusion showed good intercuspation, with an improvement on the facial profile. In the lower arch, the right second and third molars were uprighted completely. The molar occlusion was Class II on both sides. The alveolar bone condition and the periodontal status of the third molar were adequate. The distal alveolar bone of the mandibular right second molar showed a vertical bone defect. Since the third molar was impacted horizontally behind the

CHAPTER 18  Second Molar Protraction and Third Molar Uprighting

287

• Fig. 18.11  Pretreatment records. (A-E) Intraoral photographs; (F) initial lateral cephalogram; (G) initial panoramic radiograph.

second molar before treatment, the alveolar bone in that area may have been absent from the beginning (Fig. 18.16). The superimposition shows that the mandibular right second molar was purely protracted to the space of the missing mandibular first molar. The horizontally impacted third molar was uprighted. The upper anterior teeth and lip were retracted significantly (Fig. 18.17). Three years and 8 months later, the occlusion was stable. The uprighted third molar was in good condition. The distal alveolar bone level of the mandibular right second molar had not worsen. The lamina dura was clearly defined. The mandibular left second molar was recently extracted because of an endodontic problem (Fig. 18.18). 

Case Two A 22-year-old female with the mandibular left second molars presented with a scissors-bite, and the left first molar was absent. Initially, the scissors-bite was corrected and the second molar protracted. The left missing first molar space was closed completely, through full protraction of the second

molar. The third molar that was initially deeply impacted was uprighted (Fig. 18.19). 

Case Three A 22-year-old female presented with a chief complaint of upper anterior teeth protrusion. Her lower anterior teeth did not protrude, and the lower left first molar was not in good condition. After the extraction of the lower left first molar, the missing molar space had to be closed by full protraction of the second molar. After treatment, the missing mandibular left first molar space was closed completely. Although the third molar was initially deeply impacted, it was uprighted completely after second molar protraction. The periodontal condition was adequate, the lamina dura was intact, and the alveolar bone levels were appropriate (Fig. 18.20). 

Conclusion Mandibular second molar protraction into the space of missing first molars or second premolars is a predictable

288 PA RT V I I     Management of Multidisciplinary and Complex Problems

• Fig. 18.12  Treatment progress after extraction of teeth. (A-E) Progress intraoral photographs; (F) progress panoramic radiograph. Note the horizontal impaction of the right mandibular third molar.

• Fig. 18.13  Treatment progress, initial space closure.

CHAPTER 18  Second Molar Protraction and Third Molar Uprighting

• Fig. 18.14  Treatment progress, full bonding of the maxillary teeth. (A-E) Progress intraoral photographs; (F) progress panoramic radiograph. Note some degree of uprighting of the right mandibular third molar.

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•

Fig. 18.15 Treatment progress, final space closure and mandibular midline correction. (A-E) Progress intraoral photographs. Mini-implant placed on the left side for midline correction; (F) progress panoramic radiograph showing the right mandibular third molar uprighted after a tube was bonded.

•

Fig. 18.16 Final records. (A-E) Final intraoral photographs; (F) final lateral cephalogram; (G) final panoramic radiograph. Note the proper angulation of the right mandibular third molar.

• Fig. 18.17  Superimposition depicting full translatory movement of the mandibular second molar.

292 PA RT V I I     Management of Multidisciplinary and Complex Problems

•

Fig. 18.18 Records after 3 years and 8 months follow-up. (A-E) Retention follow-up intraoral photographs; (F) retention follow-up panoramic radiograph.

A

B

C

D

• Fig. 18.19  (A) Initial; (B) treatment progress; (C) posttreatment; and (D) 3 years and 7 months after debond-

ing. (Reproduced with permission from Baik UB, Kim MR, Yoon KH, Kook YA, Park JH. Orthodontic uprighting of a horizontally impacted third molar and protraction of mandibular second and third molars into the missing first molar space for a patient with posterior crossbites. Am J Orthod Dentofacial Orthop. 2017;151[3]:572-582.8)

CHAPTER 18  Second Molar Protraction and Third Molar Uprighting

A

B

C

293

D

• Fig. 18.20  Mandibular left second molar protraction after extraction of hopeless first molar. (A) Initial after

extraction of left fist molar; (B) treatment progress; (C) posttreatment; and (D) 2 years and 7 months after debonding.

procedure, when TADs are incorporated to the biomechanical approach. Currently, 212 cases of second molar protraction have been completed, of which four have failed, mainly because of periodontal problems. The failed cases were related to protraction into the first molar site. In the future, perhaps more meticulous case selection and simultaneous periodontal therapy may be able to decrease the rate of failure. In spite of the few failures, this approach has also favorable effects on impacted third molars. Dentists and other specialists should be aware of this approach, as it may reduce dental health costs and preserve the natural dentition.

References 1. Robert WE, Nelson CL, Goodacre CJ: Rigid implant anchorage to close a mandibular first molar extraction site, J Clin Orthod 28:693–704, 1994. 2. Kyung SH, Choi JH, Park YC: Miniscrew anchorage to protract lower second molars into first molar extraction sites, J Clin Orthod 37:575–579, 2003. 3. Nararaj K, Upadhyay M, Yadav S: Titanum screw anchorage for protraction of mandibular second molars into first molar extraction site, Am J Orthod Dentofacial Orthop 134:583–591, 2008. 4. Kravitz ND, Jolley T: Mandibular molar protraction with temporary anchorage devices, J Clin Orthod 42:351–355, 2008. 5. Baik UB, Chun YS, Jung MH, Sugawara J: Protraction of mandibular second and third molars into missing first molar spaces for a patient with an anterior open bite and anterior spacing, Am J Orthod Dentofacial Orthop 141(6):783–795, 2012. 6. Baik UB, Park JH: Molar protraction: orthodontic substitution of missing posterior teeth, Create Space, 2013. 7. Kim KB: Temporary skeletal anchorage devices: a guide to design and evidence-based solution, Heidelberg, Germany, 2014, Springer.

8. Baik UB, Kim MR, Yoon KH, Kook YA, Park JH: Orthodontic uprighting of a horizontally impacted third molar and protraction of mandibular second and third molars into the missing first molar space for a patient with posterior crossbites, Am J Orthod Dentofacial Orthop 151(3):572–582, 2017. 9. Baik UB, Park JH, Kook YA: Correction of bimaxillary protrusion after extraction of hopeless mandibular posterior teeth and molar protraction, J Clin Orthod 51(6):353–359, 2017. 10. Liddle DW: Second molar extraction in orthodontic treatment, Am J Orthod 72:599–616, 1977. 11. Rindler A: Effects on lower third molars after extraction of second molars, Angle Orthod 47:55–58, 1977. 12. Slodov I, Behrents RG, Dobrowski DP: Clinical experience with third molar orthodontics, Am J Orthod Dentofac Orthop 96:453– 461, 1989. 13. Richardson ME, Mills K: Late lower arch crowding: the effect of second molar extraction, Am J Orthod Dentofac Orthop 98:242– 246, 1990. 14. Richardson ME, Richardson A: Lower third molar development subsequent to second molar extraction, Am J Orthod Orthop 104:566–574, 1993. 15. Orton-Gibbs Sharon, et al.: Eruption of third permanent molars after the extraction of second permanent molars. Part 2: functional occlusion. and periodontal status, Am J Orthod Dentofac Orthop 119:239–244, 2001. 16. De-Ia-Rosa-Gay Cristina, et al.: Spontaneous third molar eruption after second molar extraction in orthodontic patients, Am J Orthod Dentofac Orthop 129:337–344, 2006. 17. De-la-Rosa-Gay C, Valmaseda-Castello´n E, Gay-Escoda C: Predictive model of third molar eruption after second molar extraction, Am J Orthod DentoFacial Orthop 137:346–353, 2010. 18. Baik UB, Kook YA, Bayome M, Park JU, Park JH: Vertical eruption patterns of impacted mandibular third molars after the mesialization of second molars using miniscrews, Angle Orthod 86(4):565–570, 2016.

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19

Class II Nonextraction Treatment With MGBM System and Dual Distal System B. GIULIANO MAINO, GIOVANNA MAINO, LUCA LOMBARDO, JOHN BEDNAR, GIUSEPPE SICILIANI

In this chapter we describe a protocol for the treatment of Class II, without compliance, that meets with predictability the aesthetic and functional requirements of the patient. In the nonextraction orthodontic therapy of Class II malocclusion we use the principle of Bidimensional Technique that divides the treatment into three well-defined phases. This enables the practitioner to readily identify unforeseen problems by careful monitoring treatment progress during each phase.1 The three phases of Bidimensional Technique include:   

Phase 1: distalization of upper molars into a “super Class I” relationship with the lower molars. Phase 2: retraction of the upper canines and premolars, consolidation of spacing between the upper incisors, and creating three groups of teeth in the maxillary arch. Phase 3: consolidation of the three groups of teeth by retracting the upper incisors.

Phase 1: Upper Molar Distalization The MGBM System2 is comprised of a passive anchorage system and an active distalization system. The passive anchorage system uses two mini-implants 10 mm in length and 1.5 mm in diameter (Spider Screw K1 HDC, Thiene, Italy) connected to a transpalatal bar. The mini-implants can be safely inserted palatally, between the second premolars and the first molars, because of the anatomic space resulting from the upper first molar single palatal root.3 Mini-implants are inserted at an angle approximately 30 to 40 degrees with respect to palatal vault inclination. In some cases, the mini-implant can be inserted between the upper first and second premolars, in the presence of wide interproximal space between these teeth. This would permit distal drifting of the upper second premolars as a result of interproximal fiber tension, during molar distalization.

A transpalatal bar (stainless steel 0.036-inch diameter) is bonded with composite on the occlusal surfaces of the upper first premolars and connected to the mini-implants by a thoroughly tightened 0.014-inch stainless steel ligature (Fig. 19.1). The palatal bar will prevent loss of anchorage and undesirable rotation, inclination, and torsion effects on the first premolars. The active distalization system is comprised of sectional 0.018 × 0.022-inch SS wires and open 200-g nickel titanium (Niti) coils, which extend 10 mm longer than the distance from the distal of the upper first premolar brackets to the mesial of the first molar tubes, on each side. The second premolars are not bracketed at this time to allow insertion of the coils. In the event that the maxillary second molars have erupted, a Simultaneous Upper Molar Distalizing System (SUMODIS) component is added to the system to distalize the second molars. This component is comprised of a double tube, a small section of 0.018 × 0.025-inch Niti wire, and two sliding crimpable stops. Before inserting and ligating the sectional 0.018 × 0.022-inch SS wire into the first premolar bracket, the lower portion of the double tube is inserted on the sectional SS wire and then an open 200-g Niti coil is inserted on the sectional SS wire, forcing the double tube against the premolar bracket. A distogingivally inclined direct bonded tube is placed on the second molar (Fig. 19.2). Two stops are crimped on the ends of a sectional 0.018 × 0.025-inch 200-g Niti wire, which is 9 mm longer than the distance from the distal of the first premolar bracket to the mesial of the second molar tube, creating an arc as it is inserted into the upper portion of the double tube, at the first premolar and the tube on the second molar (see Fig. 19.2). The active Niti wire in excess of 9 mm will distalize the upper second molar, while the compressed coil will distalize the first molar simultaneously. The distogingival inclination of the second molar tube is critical to minimize distal inclination of the second 295

296 PA RT V I I     Management of Multidisciplinary and Complex Problems

molar crown that would result from the elasticity of the Niti wire. When in presence of a severe deep bite, a removable bite plane from 3 to 3, to be used during night time, can be delivered to the patient to facilitate lower molars extrusion, open the bite, and decrease the occlusal forces on the first premolars (Fig. 19.3).

Clinical Tips for Phase 1 • The tube on the second molar should be placed with a distogingival inclination, to compensate the crown-distal tipping effect, from the use of a superelastic Niti sectional wire. • Avoid using excessive length (greater than 9 mm excess) of Niti sectional wire in the SUMODIS system to avoid soft tissue damage in the vestibule of the maxilla. • When the distalization to “super Class I” is completed on one side before the other side, a closed coil should replace the open coil and serve as a space maintainer on the “super Class I” molar side, while distalization is continued on the other side. 

Phase 2: Retraction of the Upper Premolars and Canines

• Fig. 19.1  The MGBM System.  The mini-implants are inserted on the

palatal side with an inclination of 30 to 40 degrees with respect to the palatal vault. A traspalatal bar is attached with composite to the occlusal surface of the first premolars and connected to the mini-implants with a tightened stainless steel legature.

+ 6 mm

When the upper molars have been distalized into “super Class I” relationship with the lower molars, two miniimplants, 1.5 mm in diameter and 8 to 10 mm in length (Spider Screw K1, HDC, Thiene, Italy) are inserted mesial to the upper first molars on the buccal surfaces, with a perpendicular or oblique insertion angle. The palatal miniimplants and the transpalatal bar are subsequently removed.

+ 3 mm

• Fig. 19.2  The MGBM System with SUMODIS (Simultaneous Upper Molars Distalization System).

• Fig. 19.3  Removable bite plane from canine to canine.

CHAPTER 19  Class II Nonextraction Treatment With MGBM System and Dual Distal System

The maxillary arch is bracketed and aligned by placing a superelastic wire (0.016 × 0.022-inch Niti) with stops, mesial to the upper first molars and crimpable hooks, mesial to the upper canines. A 0.012-inch steel ligature wire is attached from the mini-implants to the archwire hooks preventing molar mesial migration and loss of the Class I molar positions (Fig. 19.4). In cases with significant crowding, the maxillary molar stops can be positioned slightly mesial to the upper molar tubes to permit slight mesial molar migration from the “super Class I” positions, thereby expediting the alignment of the upper arch. Premolar and canine distalization can be initiated immediately by placing elastic chains or 50-g retraction NiTi coils from the mini-implants to the teeth. When alignment is complete, a 0.016 × 0.022-inch SS archwire with stops, mesial to the upper molars, and crimped hooks, mesial to the canines is placed. Steel ligatures (0.012-inch) are placed from the mini-implants to the hooks on the archwire and the simultaneous retraction of the upper canines and first premolars is continued using 100 to 150-g forces from the teeth to the mini-implants, which provide direct anchorage.

297

In the event that the upper molars have been distalized into “super Class I” positions, the majority of the upper second premolars will migrate distally, while passing buccally to the mini-implants, under the influence of transseptal fiber pull. If additional distal movement of the upper second premolars is required, Class I forces are applied from the first molars to the second premolars, using indirect anchorage. The Class I forces can be applied from the buccal or palatal aspects to control undesirable rotations (Fig. 19.5). The simultaneous retraction of both premolars and canines allows a significant reduction of the treatment time. Also, lower arch treatment can be delayed until the completion of Phase II, reducing the risk of caries and chairtime for possible lower arch bracket replacement emergency visits.

Clinical Tips for Phase 2 • The stops on the 0.016 × 0.022-inch SS archwire must be in contact with the first molars, and the metal ligatures between the mini-implants and the hooks must be thoroughly tight. 

Phase 3: Incisors Retraction

• Fig. 19.4  Alignment phase using a 0.016 × 0.022-inch nickel titanium

(Niti) wire, with stop crimped mesial to the maxillary first molar, and a steel ligature extending from the mini-implant to the hook crimped mesial to the maxillary canine. Simultaneous distalization of the canine and first premolar is initiated using light forces.

In the Bidimensional Technique, the incisor brackets are 0.018 × 0.025-inch and the canine, premolar, and molar brackets are 0.022 × 0.028-inch. The maximum archwire dimension for incisor retraction is 0.018 × 0.022-inch, thereby maintaining a complete couple in the anterior segment and allowing sliding through the posterior segment as incisors are retracted. When the three groups of teeth have been created and the upper canines are in Class I relationship with the lower canines, the retraction of the upper incisors is initiated using sliding mechanics, by inserting a 0.018 × 0.022-inch upper SS archwire, with hooks crimped distal to the lateral incisors, into the pretorqued 0.018 × 0.025-inch incisor

• Fig. 19.5  Phase 2. Simultaneous retraction of the first premolar and canine using coils from the mini-

implants to the teeth (direct anchorage). Retraction of the second premolar placing elastic chain from the first molar to second premolar is necessary.

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brackets. This forms a complete couple between the incisor pretorqued brackets and the archwire, thereby retracting the incisors bodily for proper incisor inclination (Fig. 19.6). The three groups of maxillary teeth are combined together and the overjet is reduced. A small section of closed coil is placed between the second premolar brackets and first molar tubes to prevent contact of the mesial roots of the first molars with the miniimplants and avoid root damage.4–5 A 0.012-inch metal ligature is placed from the miniimplants to the canines to maintain the canines and premolars in Class I relationships, with the lower arch. On each side, 300-g coils are placed from the mini-implants to the maxillary archwire hooks to retract the upper incisors (Figs. 19.7–19.15).

0.022

0.025

0.022 0.018

0.018

0.022 0.018

• Fig. 19.6  Bidimensional brackets allows complete coupling of the full -

thickness 0.018 × 0.022-inch SS wire in the pretorqued slots of the anterior brackets, for bodily incisor retraction and the accompanying sliding of the lateral segments.

•

• In cases where the root length is longer than average or whenever it is necessary to implement the torque control of the anterior region, a thicker SS wire 0.018 × 0.025inch can be used. A significant number of Class II malocclusions have a deep overbite necessitating bite opening, as the incisors are retracted.

FRONTAL AREA: UPPER INCISORS

LATERAL SEGMENT

0.028

Clinical Tips for Phase 3

• Fig. 19.7  Phase 3. The canines are tied back to the mini-implants with

metal ligatures. Incisor retraction is initiated with coils from the miniimplants to the hooks crimped on the archwire. A section of closed coil is placed between the first molars and second premolars to prevent root contact with the mini-implants.

Fig. 19.8 A male patient treated with the MGBM system without extractions: pretreatment extraoral photographs.

CHAPTER 19  Class II Nonextraction Treatment With MGBM System and Dual Distal System

• Fig. 19.9  Pretreatment intraoral photographs.

• Fig. 19.10  Phase 1 (molars distalization): beginning of distalization with SUMODIS (Simultaneous Upper Molar Distalizing System) and end of distalization, with closed coils as space maintainers.

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• Fig. 19.11  Phase 2: simultaneous retraction of the premolars and canines using buccally inserted mini-

implants as anchorage, 0.016 × 0.022-inch SS wire, with stops against the molars, metal ligature from the mini-implants and the hooks crimped on the archwire and elastic chains to retract simultaneously premolars and canines.

• Fig. 19.12  Phase III: retraction of the incisors.

• Fig. 19.13  End of treatment.

Bite opening can be achieved by upper or lower incisor intrusion, molar extrusion, or a combination of these methods, often dependent upon smile esthetics and growth patterns.6 In the use of mini-implants as anchorage, the center of resistance of the maxilla is almost coincident with the vertical height of the mini-implant. When forces are applied from the mini-implant to the anterior teeth, the resultant force retracting the incisors passes below the center of

resistance of the incisors, causing mandibular plane rotation in a clockwise direction, with molar intrusion and incisor extrusion.7–9 Power arms can be used to prevent undesirable rotation; however, they slow tooth movement, they are difficult to clean, and often cause soft tissue damage.10,11 Fortunately, the Bidimensional Technique allows a full couple of pretorqued anterior brackets and archwire, and these adverse reactions can be controlled without power arms in the majority of cases.

CHAPTER 19  Class II Nonextraction Treatment With MGBM System and Dual Distal System

If an exaggerated curve of Spee is placed in the upper archwire and a reverse curve of Spee is placed in the lower archwire, combined with vertical elastics from upper to lower molars, the molar intrusion is eliminated and the rotation of the occlusal plane is controlled. The extrusion of the incisors resulting from the forces from the mini-implants to the incisors will be controlled

301

by the intrusive force of the modified curves of Spee in the upper and lower archwires (Fig. 19.16). The use of power arms therefore could be restricted to the very severe deep bite cases (Fig. 19.17). In cases where second premolars are unerupted and second molars are erupting, before or simultaneously, with the second premolars, the mini-implants can be applied palatally to avoid interradicular insertion. Through the use of the MAPA System guide,12,13 two mini-implants 2 mm in diameter and length dependent upon the palatal bone thickness can be inserted palatally. In the same appointment, a bar connecting the palatal mini-implants and bonded on the palatal or occlusal surfaces of the premolars can be inserted in the same appointment, according to the “one visit” protocol.14 The bar bonded to the first premolars forms the passive anchorage component of MGBM system. The active distalization component placed on the vestibular side has been previously described (Fig. 19.18). 

Dual Distal System

• Fig. 19.14  Panoramic radiograph before and after treatment.

The palatal vault is many times preferred for the miniimplant insertion because there are no roots interferences. When using this location, the MGBM system is often used in combination with distalization systems, which use only palatal mechanotherapy.15,16 In fact, these palatal distalization systems often have an undesirable mesial rotation of the upper molars, causing a negative effect on the Class I relationship, which they are trying to achieve (Fig. 19.19). Furthermore, when the second molars have erupted, these palatal distalization systems become less efficient in

• Fig. 19.15  Lateral cephalometric radiograph before and after treatment.

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A

•

Fig. 19.16  Phase 3: exaggerated curve of Spee on the upper arch and a reverse curve of Spee on the lower prevent incisor extrusion. Vertical elastics in the posterior part of the mouth are inserted to prevent intrusion of the molars.

B • Fig. 19.19  (A) Mesial rotation of the molars using the palatal mechanotherapy. (B) Distal rotation using the MGBM system.

•

Fig. 19.17  Phase III: retraction of the incisors in a severe deep bite case using power arm hooks.

achieving the desired distalization in a reasonable amount of treatment time. In a comparative distalization study,17 the MGBM system produced 0.90 mm molar distalization per month, compared to a palatal system producing only 0.33 mm per month of molar distal movement. Consequently, adding the MGBM system on the buccal side renders the DUAL system far more efficient, as a result of the positive effects of the two systems, when combined (Fig. 19.20). 

Conclusion

• Fig. 19.18  MGBM system and SUMODIS (Simultaneous Upper Molar Distalizing System) with mini-implants inserted in the palatal vault.

The MGBM system represents a rational approach to the treatment of Class II malocclusions. It is a fact that the placement of mini-implants on the palatal aspect is easier because of ample interradicular space. However, the upper molars, which must be distalized, are often rotated mesially, and MGBM distalization mechanotherapy, applied to the buccal aspect, provides derotation of the molars and continued rotation control throughout the distalization process. The application of mini-implants to the palatal vault can be used solely or can be combined with other types of mechanotherapy, such as the MGBM system to increase efficiency and molar control.

CHAPTER 19  Class II Nonextraction Treatment With MGBM System and Dual Distal System

•

Fig. 19.20 Dual distal system: in presence of the erupted second molar, an MGBM system with SUMODIS (Simultaneous Upper Molar Distalizing System) is added on the buccal aspect to facilitate molar distalization.

The application of the SUMODIS system is an efficient time saving approach to the distalization of upper first and second molars simultaneously. The use of the mini-implants as direct anchorage on the buccal aspects in Phase II and Phase III, to retract the canines, premolars, and incisors, minimizes the risk of any molar anchorage loss. In the event of failure of the direct mini-implants anchorage, the molar Class I position will not be compromised. The Bidimensional Technique uses two dimensions of brackets 0.018 × 0.025-inch on the incisors and 0.022 × 0.028-inch for the canines, premolars, and molars. This provides for a complete anterior couple of the wire and bracket slot resulting in torque control of the incisors as they are retracted and facilitates the biomechanics in deep bite cases. An undersized posterior wire relative to the slot size permits sliding mechanics, as teeth are moved posteriorly into groups and as spaces are closed.

References 1. Gianelly AA: Bidimensional technique. Theory and practice, New York, 2000, GAC Int. 2. Maino BG, Gianelly AA, Bednar J, Mura P, Maino G: MGBM System: new protocol for Class II non extraction treatment without cooperation, Prog Orthod 8(1):130–143, 2007. 3. Poggio PM, Incorvati C: “Safe zones”: a guide for miniscrew positioning in the maxillary and mandibular arch, Angle Orthod 76(2):191–197, 2006.

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4. Maino BG, Weiland F, Attanasi A, Zachrisson BU, Buyukyilmaz T: Root damage and repair after contact with miniscrews, J Clin Orthod XLI(12):762–766, 2007. 5. Kadioglu O, Buyukyilmaz T, Zachrisson BU, Maino BG: Contact damage to root surfaces of premolars touching miniscrews during orthodontic treatment, Am J Orthod Dentofacial Orthop 134:353–360, 2008. 6. Zachrisson BU: Esthetic factors involved in anterior tooth display and the smile: vertical dimension, J Clin Orthod 32:432– 445, 1998. 7. Jung M, Kim T: Biomechanical considerations in treatment with miniscrew anchorage, Part I: the sagittal plane, J Clin Orthod 42(2):79–83, 2008. 8. Tominaga Jun-ya, Ozaki Hiroya: Effect of bracket slot and archwire dimensions on anterior tooth movement during space closure in sliding mechanics: a 3-dimensional Finite element study, Am J Orthod Dentofacial Orthop 146:166–174, 2014. 9. Ozaki Hiroya, Tominaga Jun-ya, Hamanaka Ryo, et al.: Biomechanical aspects of segmented arch mechanics combined with power arm for controlled anterior tooth movement: a threedimensional finite element study, J Dent Biomech 6:1–6, 2015. 10. Tominaga J, Tanaka M, Koga Y, Gonzales C, Kobayashi M, Yoshida N: Optimal loading conditions for controlled movement of anterior teeth in sliding mechanics, Angle Orthod 79(7):1102, 2009. 11. Rokutanda Hiromi, Koga Yoshiyuki, Yanagida Hiroko, Tominaga Jun-ya, Fujimura Yuji, Yoshida Noriaki: Effect of power arm on anterior tooth movement in sliding mechanics analyzed using a three-dimensional digital mode, Orthod Waves 74:93– 98, 2015. 12. Maino BG, Paoletto E, Lombardo L, Siciliano G: MAPA: a new high-precision 3D method of palatal miniscrew placement, Eur J Clin Orthod 3(2):41–47, 2015. 13. Maino BG, Paoletto E, Lombardo L, Siciliani G: A three-dimensional digital insertion guide for palatal miniscrew placement, J Clin Orthod 50(1):12–22, 2016. 14. Maino BG, Paoletto E, Lombardo L, Siciliani G: From planning to delivery of a bone-borne rapid maxillary expander in one visit, J Clin Orthod LI(4):198–207, 2017. 15. Cozzani M, Zallio F, Lombardo L, Gracco A: Efficiency of the distal screw in the distal movement of maxillary molars, World J Orthod 11(4):341–345, 2010. 16. Wilmes B, Drecher D: Application and effectiveness of the Beneslider: a device to move molar distally, World J Orthod 11(4):331–340, 2010. 17. Cozzani M, Fontana M, Maino BG, Maino G, Palpacelli L, Caprioglio A: Comparision between direct vs indirect anchorage in two miniscrew-supported distalizing devices, Angle Orthod 86:399–406, 2016.

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Anchorage of TADs Using Aligner Orthodontics Treatment for Lower Molars Distalization KENJI OJIMA, JUNJI SUGAWARA, RAVINDRA NANDA

Introduction In recent years, challenging aligner treatments, which require molar control, have become a possibility.1–12 There have been several reports of positive results of aligner treatments with maxillary molar distalization. We would like to share with you two cases that we treated with Invisalign in which we performed mandibular molar distalization using miniimplants on the lower molars as anchorage for elastics. 

Case One The patient was a 27-year-old female whose chief complaint was lateral openbite, leading to impaired mastication and lower anterior crowding, as well as desire to improve the facial profile. The patients’ facial configuration displayed frontal symmetry, with a slight protrusion of the lower lip. Intraorally, the upper and lower midline were approximately in line, central incisors displayed edge-to-edge bite, the upper and lower canines and first molars were in Class III relationship with anterior crowding, and an excessive curve of Spee, with a pronounced lateral openbite. Furthermore, compared to the lower dentition, the upper dental arch was contracted. Occlusion was unstable. Results of the cephalometric analysis showed that the ANB was −1.1 degrees, Wits −10.0, compared to the maxilla, the mandible was further forward, the mandibular plane was open in a skeletal Class III relationship. With regards to the incisor tooth axis, both upper and lower incisors displayed lingual inclination. A panoramic x-ray showed no pathologies, the upper and lower third-molars on both sides had been extracted and there were no locations of pathologic root resorption identified (Figs. 20.1–20.3).

Treatment Goals We planned lower molars distalization to achieve Class I relationship and improve the facial profile through

improvement of the molar relation, edge-to-edge bite of the incisors, and the lateral openbite. 

Treatment Alternatives There were three possible treatments to achieve the treatment goals. The first option was a combined orthodontic treatment option, including a sagittal split ramus osteotomy (BSSO). Treatment time would be 24 months. The second option, while nonsurgical, included extraction of all four upper and lower premolars (treatment time 24 months). The third option was more ambitious than the other two: nonextraction distalization of the posterior and lateral lower teeth, using a removable aligner (predicted treatment time between 30 and 36 months). After receiving an explanation of the benefits and drawbacks of each option, the patient expressed interest in the option that was least conspicuous, nonsurgical, nonextraction, with the lowest expectation of a large change in the facial profile and potential to finish in 2 years’ time. Following a comprehensive examination of patient needs and treatment options, the third option, treatment with aligner technology Invisalign System,13–28 was chosen. 

Treatment Progression The aligner treatment began with a three-dimensional intraoral scan of the teeth and occlusion, followed by a treatment simulation using ClinCheck. The treatment plan was decided based on this simulation (Fig. 20.4). The main tooth movements were as follows: 1. Distalization of the lower molars (approx. 4 mm) to achieve a Class I relation. 2. Intrusion of the lower molars to produce an appropriate overbite. 3.  Lateral expansion of the upper dental arch (approx. 7 mm). 305

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G • Fig. 20.1  (A–E) Pretreatment intraoral photos. (F–G) Pretreatment extraoral photos.

• Fig. 20.2  Pretreatment panoramic radiograph.

Attachments were not used from initial insertion of the aligner and attached after 1 month into treatment. Rectangular attachments were affixed to the lower teeth from the molars to the canines (Fig. 20.5). After the second month, we began distalization of the lower molars, planned to move one tooth at a time in sequence, beginning with the rear-most molars. Following the completion of molar distalization, we began distalization of the premolars (Fig. 20.6). To prevent mesial drift and create an anchor for the distalization of teeth, from the canines forward, temporary anchorage devices (TADs) were installed between the lower first molar and second molar and elastics were used (Figs. 20.7–20.9). Following the completion of molar and premolar distalization, we began distalization of the canines

• Fig. 20.3  Pretreatment lateral cephalogram.

and incisors and finished with an optimal overbite of the anterior teeth. During treatment, after the first 10 months of aligner use, minor imperfections were detected such as slight torsion of

CHAPTER 20  Anchorage of TADs Using Aligner Orthodontics Treatment for Lower Molars Distalization

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• Fig. 20.5  Attachment on.

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• Fig. 20.6  Start mandibular molar distalization and intrusion maxillary molars.

• Fig. 20.7  Sequential distalization of mandibular molars. Then place temporary anchorage devices (TADs) between #36,37 and #46,47 for retraction #34,44.

• Fig. 20.8  After finished distalization premolar then retraction #33,43 using temporary anchorage devices (TADs).

• Fig. 20.9  Mandibular anterior retraction.

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• Fig. 20.10  (A–E) Posttreatment intraoral photo. (F–H) Posttreatment extraoral photo.

the lower canines and lower incisors, and we planned for extra aligners for refinement and finishing (Fig. 20.10). Following the completion of treatment, Vivera retainers were used to retain the position. 

Treatment Results Examination of the posttreatment facial profile photographs show that tension in the lips had been relaxed and the lower lip had retracted slightly. The patient was satisfied with this result. Intraoral pictures showed that an appropriate overjetbite had been achieved, upper and lower canines and molars had achieved Class I relation, and lateral openbite had been perfectly improved. Posttreatment, dental arch width had greatly increased, but molars achieved good occlusion. The final situation is in line with the final ClinCheck simulation results (Fig. 20.11). Crowding in the lower anterior teeth had been relieved and, while there was slight retraction in the interdental papilla, it was barely noticeable and no periodontal pockets had formed. Posttreatment panoramic x-rays showed maintained dental parallelism, with no obvious root resorption in the alveolar bone (Fig. 20.12). Superimposed pre- and

posttreatment cephalometric analyses show no anteriorposterior shift of the mandible and a slight counterclockwise rotation (Fig. 20.13) and cephalometric analysis data. Upper incisors exhibited a slight labial inclination and extrusion and lower incisors exhibited labial inclination and extrusion. The upper first molars exhibited almost no change (Fig. 20.14). At the end of treatment, 20 stages of upper aligners and 61 stages of lower aligners were used over 10 months. In refinement, an additional 6 months were added to treatment with 10 additional upper stages and 34 lower stages for a total of 16 total months of treatment. One-year posttreatment and occlusion was stable with no change (Figs. 20.15 and 20.16). 

Case Two The patient was an 18-year-old male with a chief complaint of anterior openbite. In his facial appearance, an intraoral and radiography findings on the first examination, extension of the lower face, crowding and dental compensation of the upper and lower dentitions, and openbite between the premolars were observed. In the skeletal findings,

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• Fig. 20.11  (A–E) Posttreatment ClinCheck software simulation.

• Fig. 20.12  Posttreatment panoramic radiograph.

mandibular overgrowth-associated mandibular protrusion was noted (Figs. 20.17 and 20.18). Based on these observations, the patient was diagnosed with skeletal mandibular protrusion and surgical orthodontic treatment was indicated; orthodontic treatment using an aligner and TADs was selected. Before the initiation of treatment, tooth movement was predicted by computer simulation software (ClinCheck) and attachments were set as shown (Fig. 20.19). When this patient came to our clinic, we determined they were a skeletal Class III and a candidate for orthognathic

• Fig. 20.13  Posttreatment lateral cephalogram.

CHAPTER 20  Anchorage of TADs Using Aligner Orthodontics Treatment for Lower Molars Distalization

surgery. However, both the patient and their mother had strong feelings against orthognathic surgery, but still sought a significant aesthetic improvement. Our treatment plan for this patient included attachment of TADs on the lower molars, as anchorage for aligners with elastics, a camouflage treatment.

Treatment Progression Treatment plan combined with distalization of the mandibular molars and concomitant use of TADs was planned. Considering the biomechanics of the teeth, distalization of the mandibular molars by elastic rubber traction using TADs, counterclockwise rotation of the mandible setting the rotation center at the mandibular premolars by intrusion of the upper and lower molars, and extrusion of the maxillary anterior tooth region were planned (Fig. 20.20). 

Treatment Results Sequential distalization of the mandibular molars using TADs and counterclockwise rotation of the mandibular body by intrusion of the molars were simultaneously performed over the treatment period, and not only improvement of the anterior tooth overbite, but also construction of a functional Class I occlusion in the molar region were achieved (Figs. 20.21

Palatal Plane at anterior nasal spine (ANS)

Black: Pre Treatment Red: Post Treatment

Mandibular Plane at Me

• Fig. 20.14  Lateral cephalometric superimpositions between the pre-

treatment and posttreatment stages: overall, maxilla, and mandible. Maxillary incisors exhibited a slight labial inclination and extrusion and mandibular incisors exhibited labial inclination and extrusion. The maxillary fist molars exhibited almost no change.

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and 20.22). The duration of treatment was 43 months, and the occlusal state improved as simulated by ClinCheck (Fig. 20.23). As of 2 months after completion of orthodontic treatment, the occlusal state has been stable. When cephalograms were superimposed, forward movement of the mandible by counterclockwise rotation of the mandibular body predicted before treatment was observed, and the anterior tooth overbite had significantly improved (Fig. 20.24). 

Discussion When planning a treatment using a digital planning infrastructure, such as that with the Invisalign system, you must consider not only the ClinCheck, but if TADs are used for anchorage, you must also consider biomechanics and reactionary force in your treatment plan. Furthermore, when planning mandibular molar distalization, you must also consider the condition of the jaw bone and roots. It has been suggested in the literature that, by using TADs to secure anchorage, molar distalization procedures in an aligner treatment have indeed become possible. However, the most effective movement plan is not simultaneous, but sequential staging. Since its release, the modern aligner system has gone through various improvements, evolving to expand the range of possible treatments to a wider variety of complicated malocclusion. Compared to the long history of edgewise methods, however, to predict the safe and accurate completion of this treatment, with a high degree of certainty, would be challenging. Furthermore, with molar distalization in cases of openbite, to avoid the molar raising wedge effect, what we considered to be the key to the success of this treatment, we decided that rather than an en masse movement using TADs and extraoral force, would opt for a more time consuming, but safer treatment plan, with individual tooth movements, which would allow a greater degree of control. We explained to the patient that treatment with aligners could take up to 3 years and that she should not expect a drastic improvement in facial profile. The patient agreed to use assistive TADs to prevent mesial movement of the distalized teeth. We were especially concerned with the distalization of the first and second lower molars and, after distalization of the second molar, half of the total movement distance, we began distalization of the first molar. When we began retraction of the premolars, to prevent mesial movement of the molars moved thus far, we had implanted TADs between the first and second molars, which had unfortunately come loose midtreatment and we reattached them to the distal side of the second molar.

• Fig. 20.15  ClinCheck software superimposition.

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E • Fig. 20.16  (A–E) Intraoral situation after 1-year retention.

When treating overbite, our main goal is to increase the depth of the anterior occlusal bite. Schupp has reported that, in his aligner treatments, he has used attachments to achieve not relative, but absolute extrusion. With KIM using the edgewise method (MEAW), he reported that it is necessary to change the occlusion plane.28–32 Results from the present study also indicate absolute extrusion of the anterior teeth and inclination of the occlusal plane. In our plan to move teeth with aligners, movements can be roughly divided into distalization of the lower posterior teeth, followed by retraction of the incisors. During each clinical visit, we checked to see whether or not tooth movement was consistent with the ClinCheck to ensure sufficient adaptation of each aligner.33–38 As a result, the number of

aligners and the overall treatment time naturally increased. The original treatment plan called for 61 stages, with maximum movement of a single stage of 0.25 mm over a 2-week period, this equated to treatment time exceeding 30 months. To reduce the period of treatment, we including the use of OrthoAccel’s AcceleDent, an accelerated orthodontic device, which we have used repeatedly to achieve effective results39–44 (see intraoral picture 1 year after retention). There is controversy about the effectiveness of this device. It is thought that effectiveness with multi-bracket system (MBS) depends on a number of factors, including the type of brackets, wire size and shape, method of wire ligation. It is difficult to say that aligners, a wireless option that instead covers the teeth to move them, is not affected by similar

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H • Fig. 20.17  (A–C) Pretreatment extraoral photo. (D–H) Pretreatment intraoral photo.

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F • Fig. 20.20  (A and B) Upper and lower molars intrusion and anterior extrusion first. (C and D) Upper molar

intrusion and anterior extrusion. Molar molars distalization sequentially using temporary anchorage devices (TADs). (E and F) Posttreatment, #33,43 retraction using TADs, then lower anterior retraction.

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Fig. 20.20, cont’d 

restrictions, and thus it is impossible to say that aligners are the best fit for the device. Still, by using an accelerated orthodontic device, not only is treatment time decreased and aligner fit improved, but the pain and discomfort that usually accompanies the initial insertion of a new aligner stage is also decreased. The benefits of accelerated orthodontics extend beyond the orthodontist to the patient as well. 

Conclusion In this study, favorable occlusion was achieved in a Class III patient using aligners to perform a nonextraction distalization treatment in the mandible. Furthermore, the use of an

accelerated orthodontic device enabled drastic reduction of the overall treatment time, but also an aligner change of every 7 days seems to be working well, allowing a shortening of the former treatment time of 50%. I believe that aligner treatments require their own special brand of treatment planning and approach, which considers the unique biomechanics in play. It is my belief that one of the unique advantages of aligners over traditional MBS treatments is the ability to effectively harness bite force for treatment, because of the aligners complete coverage of the teeth. In addition to being able to easily perform molar intrusion, the simplicity and elegance of the device and its mechanics make

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H • Fig. 20.21  (A–F) Posttreatment intraoral photo. (G–H) Posttreatment extraoral photo.

aligners a less threatening orthodontic option for patients. Furthermore, compared to a similarly clean-looking and invisible orthodontic system, like lingual brackets, the patient’s mouth is kept in a far more hygienic state and there is a lower risk of inflammation. The appeal of aligners is compounded by the fact that, other than the TADs, they are fully removable for dining, which places less pressure

on patients and ultimately is a factor in higher treatment motivation. Treatment possibilities with aligners have moved beyond simple anterior crowding cases and now can be effectively used to treat a wide variety of malocclusion treatments, such as four-premolar extraction, nonextraction maxillary molar distalization, openbite, and deep bite.

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B • Fig. 20.22  (A) Posttreatment lateral cephalogram. (B) Posttreatment panoramic radiograph.

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• Fig. 20.23  (A–C) Posttreatment ClinCheck software simulation.

Initial Final

• Fig. 20.24  Lateral cephalometric superimpositions between the pretreatment and posttreatment stages.

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References 1. Yazdani AA: Transparent aligners: an invisible approach to correct mild skeletal class III malocclusion, J Pharm BioAllied Sci 7:301–306, 2015. 2. Schupp W, Haubrich J, Hermens E: Möglichkeiten und grenzen der schienentherapie in der kieferorthopädie, Zahnmed Update 2:171–184, 2013. 3. Schupp W, Haubrich J, Neumann I: Class II correction with the Invisalign system, J Clin Orthod 44:28–35, 2010. 4. Bowman SJ, Celenza F, Sparaga J, et  al.: Creative adjuncts for clear aligners, Part 3: extraction and interdisciplinary treatment, J Clin Orthod 49:249–262, 2015. 5. Bowman SJ, Celenza F, Sparaga J, et  al.: Creative adjuncts for clear aligners, part 2: intrusion, rotation, and extrusion, J Clin Orthod 49:162–172, 2015. 6. Bowman SJ, Celenza F, Sparaga J, et  al.: Creative adjuncts for clear aligners, part 1: class II treatment, J Clin Orthod 49:83–194, 2015. 7. Schupp W, Haubrich J: Aligner orthodontics, Berlin, 2015, Quintessence Publishing. 8. Lin JC, Tsai SJ, Liou EJ, Bowman SJ: Treatment of challenging malocclusions with invisalign and miniscrew anchorage, J Clin Orthod 48:23–36, 2014. 9. Ojima K, Dan C, Nishiyama R, Ohtsuka S, Schupp W: Accelerated treatment with invisalign, J Clin Orthod 48:487–499, 2014. 10. Orton-GibbsS, Kim NY: Clinical experience with the use of pulsatile forces to accelerate treatment, J Clin Orthod 49:557–573, 2015. 11. Bowman SJ: The effect of vibration on the rate of leveling and alignment, J Clin Orthod 48:678–688, 2014. 12. Nagasaka H, Sugawara J, Kawamura H, Nanda R: “Surgery first” skeletal class III correction using the skeletal anchorage system, J Clin Orthod 43:97–105, 2009. 13. Vlaskalic V, Boyd R: Orthodontic treatment of a mildly crowded malocclusion using the Invisalign system, Austral Orthod J 17:41–46, 2001. 14. Boyd RL, Miller RJ, Vlaskalic V: The Invisalign system in adult orthodontics: mild crowding and space closure cases, J Clin Orthod 34:203–212, 2000. 15. Giancotti A, Di Girolamo R: Treatment of severe maxillary crowding using Invisalign and fixed appliances, J Clin Orthod 43:583–589, 2009. 16. Schupp W, Haubrich J, Neumann I: Treatment of anterior open bite with the Invisalign system, J Clin Orthod 44:501–507, 2010. 17. Guarneri MP, Oliverio T, Silvestre I, Lombardo L, Siciliani G: Open bite treatment using clear aligners, Angle Orthod 83:913– 919, 2013. 18. Krieger E, Seiferth J, Marinello I, et al.: Invisalign treatment in the anterior region, J Orofac Orthop 73:365–376, 2012. 19. Fiorillo G, Festa F, Grassi C: Upper canine extraction in adult cases with unusual malocclusions, J Clin Orthod 46:102–110, 2012. 20. Simon M, et  al.: Treatment outcome and efficiency of an aligner technique—regarding incisor torque, premolar derotation and molar distalization, BMC Oral Health 14:68–74, 2014.

21. Giancotti A, Farina A: Treatment of collapsed arches using the Invisalign system, J Clin Orthod 44:416–425, 2010. 22. Boyd RL: Esthetic orthodontic treatment using the Invisalign appliance for moderate to complex malocclusions, J Dent Educ 72:948–967, 2008. 23. Castroflorio T, Garino F, Lazzaro A, Debernardi C: Upperincisor root control with Invisalign appliances, J Clin Orthod 47:346–351, 2013. 24. Schupp W, Haubrich J, Neumann I: Invisalign treatment of patients with craniomandibular disorders, Int Orthod 8:253–267, 2010. 25. Womack WR: Four-premolar extraction treatment with Invisalign, J Clin Orthod 40:493–500, 2006. 26. Boyd RL: Complex orthodontic treatment using a new protocol for the Invisalign appliance, J Clin Orthod 41(9):525–547, 2007. 27. Lagravere MO, Flores-Mir C: The treatment effects of Invisalign orthodontic aligners: a systematic review, J Am Dent Assoc 136:1724–1729, 2005. 28. Giancotti A, et al.: A mini screw-supported intrusion auxiliary for open-bite treatment with Invisalign, J Clin Orthod 48(6):348– 358, 2014. 29. Kim YH: Anterior openbite and its treatment with multiloop edgewise archwire, Angle Orthod 57:290–321, 1987. 30. Handelman CS: The anterior alveolus: its importance in limiting orthodontic treatment and its influence on the occurrence of iatrogenic sequence, Angle Orthod 66:95–109, 1996. 31. Yang WS, Kim BH, Kim YH: A study of the regional load deflection rate of multiloop edgewise arch wire, Angle Orthod 71(2):103–109, 2001. 32. Janson D, et  al.: Orthodontic treatment alternative to a class III subdivision malocclusion, J Appl Oral Sci 17(4):354–363, 2009. 33. Oh YH, Park HS, Kwon TG: Treatment effects of micro implantaided sliding mechanics on distal retraction of posterior teeth, Am J Orthod Dentofacial Orthop 139:470–481, 2011. 34. Chung K, Kim SH, Kook Y: C-Orthodontic micro implant for distalization of mandibular dentition in class III correction, Angle Orthod 75:119–128, 2005. 35. Baik UB, Chun YS, Jung MH, Sugawara J: Protraction of mandibular second and third molars into missing first molar spaces for a patient with an anterior open bite and anterior spacing, Am J Orthod Dentofacial Orthop 141:783–795, 2012. 36. Safavi SM, Younessian F, Kohli S: Miniscrew-assisted mandibular molar distalization in a patient with skeletal class-III malocclusion: a clinical case report, APOS Trends Orthod 3:83–88, 2013. 37. Bourgui F: Issues in contemporary orthodontics. In Paulo Beltrão. Class III high angle malocclusion treated with orthodontic camouflage (MEAW Therapy), Intech, 2015, pp 219–241. 38. Ravera S, Castroflorio T, Garino F: Maxillary molar distalization in adult patients with Invisalign, Eur J Clin Orthod 2:3, 2014. 39. Yadav S, et  al.: The effect of low-frequency mechanical vibration on retention in an orthodontic relapse model, Eur J Orthod 38:44–50, 2015. 40. Brugnami F, Caiazzo A, Dibart S: Lingual orthodontics: accelerated realignment of the “social six” with piezocision, Compend. Cont Ed Dent 34:608–610, 2013.

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41. Camacho AD, Velásquez Cujar SA: Dental movement acceleration: literature review by an alternative scientific evidence method, World J Methodol 4:151–162, 2014. 42. Kau CH, Nguyen JT, English JD: The clinical evaluation of a novel cyclical force generating device in orthodontics, Orthod Pract U.S 1:10–15, 2010.

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43. Woodhouse NR, DiBiase AT, Johnson N, et al.: Supplemental vibrational force during orthodontic alignment: a randomized trial, J Dent Res 94:682–689, 2015. 44. Orton-Gibbs S, Kim NY: Clinical experience with the use of pulsatile forces to accelerate treatment, J Clin Orthod 49:557–573, 2015.

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Index A Acrylic cap, 152–153 Aligner, start during distalization, 74–80, 76t, 78f–83f, 80t Alveolar ridge development, vertical, mini-implants in, 278, 280f–281f Anchor loss, 29 Anchorage devices, temporary, management of multidisciplinary patients with, 263–282 in compromised maxillary incisors, 274–275, 274f–275f endosseous dental implants, for missing posterior teeth, 265, 268f–270f mini-implants in vertical alveolar ridge development, 278, 280f–281f for preprosthetic space appropriation, 265, 266f–267f ridge mini-implants for orthodontic anchorage, 267– 274, 271f–273f skeletal anchorage in orthognathic surgery, 275, 276f–279f for space development for implant in congenitally missing lateral incisor, 263, 264f–265f Angle class II Division I subdivision right hand, 73–74 Angle class II malocclusion, 71 Anterior crossbite, 89, 244f–248f case summary of, 89, 91f diagnosis of, 89 extraoral analysis of, 89t intraoral analysis and functional analysis of, 90t problem list for, 90t smile analysis of, 90t treatment objectives of, 92t treatment options of, 89, 93f–98f treatment sequence and biomechanical plan, 92t Anterior crowding, mandibular, 183–184, 186f Anterior occlusion, edge to edge, 184, 187f–189f Anterior openbite, 149, 156, 159f classification of, 149 lower molars distalization for, 309–311, 313f–314f treatment progression for, 311, 314f–315f treatment results for, 311, 316f–317f problem list of, 160 treatment objectives of, 160 treatment plan of, 160

Anterior openbite (Continued) treatment results of, 160, 161f–162f treatment sequence of, 160 Anterior teeth bimaxillary extrusion without TADs, 244 crowding, 89–98 case summary of, 98–99, 100f diagnosis of, 98–99, 100f extraoral analysis of, 98t intraoral analysis and functional analysis, 99t problem list, 99t smile analysis of, 98t treatment objectives of, 101t treatment options of, 99, 102f–107f treatment sequence and biomechanical plan of, 101t Appliance fabrication, 62, 64f–65f Arch asymmetry, upper and lower, 126, 132, 134f Asymmetrical malocclusion, cause of, 170 B Beneslider appliance, 73f with aligners, 71–86 clinical considerations of, 80–83 clinical procedure and rationale of, 72–80 during distalization, 74–80, 76t, 78f–83f, 80t simultaneous start of, 73–74, 75f–77f strategies and clinical tips, 72–73, 74f Bilateral mandibular i-station, 48–51 Bilateral sagittal split osteotomy, simultaneous mandibular advancement with, 113, 116f Bimaxillary anterior crowding, with bioefficient skeletal anchorage, nonextraction treatment of, 87–108 Bimaxillary dental protrusion, decompensation of a retreatment case presenting with, 113–120, 118f considerations of, 117 final facial outcome of, 120, 124f problem list, 116–117 treatment goals of, 117 treatment of, 117–120, 119f, 122f–123f Bimaxillary extrusion and single-dentition extrusion, 257–260 without TADs, 243–245, 244f–249f bite raisers to backward rotate mandible, 243

Note: Page numbers followed by “f ” indicate figures, “t” indicate tables, and “b” indicate boxes. 321

322

Index

Bimaxillary extrusion (Continued) extrusion of anterior teeth to close anterior openbite, 244 extrusion of posterior teeth, 245 preparation for, 243 Bioefficient skeletal anchorage, nonextraction treatment of bimaxillary anterior crowding with, 87–108 Biomechanics, 3 in distalizing molars with buccal TADs, 195–196, 196f Bite raisers in bimaxillary extrusion without TADs, 243 in single-dentition extrusion with TADs in mandible, 254 Bodily movement, 11 Brazilian kit, 212 Buccal alveolar mini-implants, 29–30 Buccal bars, 152 Buccal segment, protraction of, 276f–279f Buccal shelf area mini-implants in, placement of, 209f, 213–215 TAD site in, 25–26, 26f Buccal temporary anchorage devices biomechanics in distalizing molars with, 195–196, 196f for distalization of teeth, 195–208 distalizing molars by, 195 stability of distalization by, 196–197 treatment outcome of distalization by, 196 Burstone bracket, 263 C CBCT. see Cone-beam computed tomography Center of gravity, 6, 6f Center of mass, 6 Center of resistance (CR), 6, 6f of maxillary posterior segment, 150, 151f Center of rotation (CROT), 9, 10f estimating, 10–12, 10f moment-to-force (M/F) ratios in, 11–12 types of tooth movement in, 10–11, 10f Centric force, 6 Cephalogram, lateral, 50f, 52f, 55f, 58f Cephalometric analysis, 45, 47, 50f, 55f Class I molar relationship, 283, 283f–284f Coincident midline, 183 Collapsed dental occlusion, 192 Cone-beam computed tomography (CBCT), 61–62, 61f for partial anterior crossbite, 89, 93f for upper and lower anterior teeth, 98f, 102f, 107f Congenitally missing lateral incisor, space development for implant in, temporary anchorage devices for, 263, 264f–265f Controlled tipping, 11 Conventional noncompliance appliances, 165

Conventional techniques, in mini-implants, 12 Couple, defined, 7–8, 7f–8f CROT. see Center of rotation Crowding in upper and lower anterior teeth, 89–98 case summary of, 98–99, 100f diagnosis of, 98–99, 100f extraoral analysis of, 98t intraoral analysis and functional analysis, 99t problem list, 99t smile analysis of, 98t treatment objectives of, 101t treatment options of, 99, 102f–107f treatment sequence and biomechanical plan of, 101t upper and lower arch, 166 diagnosis and case summary of, 166–168 extraoral analysis for, 166, 167f final result of, 170, 171f–172f functional analysis for, 166 intraoral analysis for, 166 problem list of, 168 smile analysis for, 166, 167f treatment objectives of, 168 treatment options of, 168 treatment sequence and biomechanical plan for, 168f–170f, 169 treatment sequence of, 170 in upper and lower teeth, 89 case summary of, 89, 91f diagnosis of, 89 extraoral analysis of, 89t intraoral analysis and functional analysis of, 90t problem list for, 90t smile analysis of, 90t treatment objectives of, 92t treatment options of, 89, 93f–98f treatment sequence and biomechanical plan of, 92t C-tube microplates, managing complex orthodontic tooth movement with, 181–194 clinical report of, 183–186, 186f–192f methods of, 183, 184f–185f C-tube pushing mechanism, 183, 185f D Dental asymmetry, treatment of, 189 Dental openbite, 149 Dentition extrusion, single, with TADs in mandible, 250–254, 250f–255f bite raisers and extrusion of upper anterior teeth, 254 extrusion of posterior teeth, 254 insertion of TADs, 250 in maxilla, 254, 256f–259f

Index

Distalization of dentition using loop mechanics, 44, 48f and intrusion using loop mechanics, 56f of mandibular molars, in skeletal III, angle class III case, 200–202 diagnosis of, 200–201, 200f, 201t retention of, 202, 203f superimposition of, 202, 203f treatment plan of, 201 treatment progress of, 201, 202f treatment results of, 201, 202f of maxillary and mandibular molars in skeletal II, angle class II bimaxillary case, 203–207 diagnosis of, 203, 204f, 204t retention of, 206, 206f superimposition of, 206–207, 206f treatment plan of, 205 treatment progress of, 205, 205f treatment results of, 205–206, 205f of maxillary molars in skeletal II, angle class II case, 197–200 diagnosis of, 197, 197f, 198t retention of, 199, 199f superimposition of, 199–200, 200f treatment plan of, 197–199, 198f treatment progress of, 197 treatment results of, 197–199, 199f in mini-implant assisted retraction, 16–17, 17f retention of of mandibular molars, 202, 203f of maxillary molars, 197–200, 199f using i-stations, 57f Distalizing molars biomechanics in, with buccal TADs, 195–196, 196f methods of, 195 by TADs, 195 stability of, 196–197 treatment outcome of, 196 Dual distal system, 301–302, 302f–303f Dynamics, 3 E Eccentric force, 6 Edentulous span, 270–273 Edge to edge anterior occlusion, 184, 187f–189f Efficient force systems, 43–44, 46f–48f Elastomeric chain, 112, 120 Endosseous dental implants, for missing posterior teeth, temporary anchorage devices in, 265, 268f–270f Equilibrium, 8 in orthodontics, 8, 8f

Equivalent force systems, 8–9, 9f Extraalveolar anchorage, with i-station device, 43–44, 44f–45f light and efficient force systems, 43–44, 46f–48f Extraalveolar implants, 209–220 benefits of, 215 in buccal shelf area, 210f characteristics of, 211–213, 214f–218f in extraalveolar site, 209f–210f final considerations for, 215 indications for, 210–211, 211f–213f infrazygomatic crest (IZC) area, 210f magnitude of the force applied, 215 placement techniques for, 213 buccal shelf, 213–214 buccal shelf region, 209f, 215 infrazygomatic crest, 208f, 213 precautions of, 215 Extraalveolar mini-implants, 30 Extraalveolar sites, for implants, 209f–210f Extraoral photographs, of mandibular deviation, 45, 49f, 52f postretention, 46–47, 53f posttreatment, 58f pretreatment, 47, 54f Extrusion, 38 bimaxillary and single-dentition extrusion, 257–260 without TADs, 243–245, 244f–249f single-dentition, with TADs in mandible, 250–254, 250f–255f in maxilla, 254, 256f–259f F Fabrication, of openbite appliance, 152–153 Facial profile improvement, in class III malocclusion, orthognathic camouflage with temporary anchorage devices for, 243–262 bimaxillary extrusion and single-dentition extrusion, 257–260 without TADs, 243–245, 244f–249f maxillary vertical development, 254–256 orthodontic extrusion stability, 260 single-dentition extrusion with TADs in mandible, 250–254, 250f–255f in maxilla, 254, 256f–259f Failed growth modification/camouflage in skeletal class II, reversing effects of, 110–112, 113f–115f considerations of, 112 problem list, 110 treatment goals, 112 treatment of, 112

323

324

Index

FHP. see Frankfort horizontal plane Fixed lingual retainers, 154 Force, 3, 4f directional effects of, 4–6, 5f effects on system, 4, 5f Force arm, 6 Force diagrams, 4–6 Force system through time, 14, 16f Force vectors, 4–6, 4f Frankfort horizontal plane (FHP), 4–5 Free vector, 7 G Gingivectomy, 38 H Hawley type retainers, 120 Horizontally impacted third molars, 286–287, 287f–293f Hybrid model, with mini-implant anchorage, 17–19, 18f–19f I Idiopathic condylar resorption (ICR), 132 Impacted third molars, horizontally, 286–287, 287f–293f Implants extraalveolar, 209–220 benefits of, 215 in buccal shelf area, 210f characteristics of, 211–213, 214f–218f in extraalveolar site, 209f–210f final considerations for, 215 indications for, 210–211, 211f–213f infrazygomatic crest (IZC) area, 210f magnitude of the force applied, 215 placement techniques for, 213 buccal shelf, 213–214 buccal shelf region, 209f, 215 infrazygomatic crest, 208f, 213 precautions of, 215 multipurpose, 150–151, 150f–151f possible complications of, 151 removal of, 151 surgical method for, 150–151, 151f IMTEC Ortho mini-implants, 263, 264f–265f, 275 Incisors mechanics to apply labial crown torque, 45–51, 49f retraction mechanical factors, 17–19, 17t, 18f in MGBM system, for class II nonextraction, 297– 301, 298f–302f

Inflammation, multipurpose implant and, 151 Infrazygomatic crest, mini-implants in, placement of, 208f, 213 Infrazygomatic (IZ) Lomas mini-implant, 265, 266f–267f Infrazygomatic temporary anchorage device, for anchorage, 274f–275f Interdisciplinary plan, 120 Interradicular mini-implants, 29–30 Intraoral photographs, of mandibular deviation, 45, 49f, 52f postretention, 46–47, 53f posttreatment, 58f pretreatment, 47, 54f Intrusion, 38 I-station, predictable management with, 43–60 extraalveolar anchorage through, 43–44, 44f–45f light and efficient force systems, 43–44 mechanics to apply labial crown torques, 45–51, 49f L Lateral incisors, upper, missing, space closure for, 33–42 interdisciplinary aspects of, 38 canine, 38 first premolar, 38 orthodontic space closure for, 35, 37f palatal screw selection and insertion for, 35–38 prosthetic-implantologic solution for, 35, 36f therapy options to replace, 35, 36f Lateral openbite, with anterior crowding, lower molars distalization for, 305–309, 306f treatment alternatives for, 305 treatment goals for, 305 treatment progression for, 305–309, 307f–309f treatment results for, 309, 310f Left dentition, masticating problem with, 184–186, 189f–192f Light force systems, 43–44, 46f–48f Line of action, 6 Lomas mini-implant, 273–274, 278 Lomas Quattro mini-implant, 269 Loop mechanics comparison of sliding mechanics and, 44, 47f distalization of dentition, 44, 48f maxillary bilateral molar distalization, 56f range of movement, 44, 48f Lower arch crowding, 166 diagnosis and case summary of, 166–168 extraoral analysis for, 166, 167f final result of, 170, 171f–172f functional analysis for, 166 intraoral analysis for, 166

Index

Lower arch crowding (Continued) problem list of, 168 smile analysis for, 166, 167f treatment objectives of, 168 treatment options of, 168 treatment sequence and biomechanical plan for, 168f–170f, 169 treatment sequence of, 170 Lower fixed appliances, 112 Lower molars distalization, anchorage of TADs for, 305–320 anterior openbite, 309–311, 313f–314f treatment progression for, 311, 314f–315f treatment results for, 311, 316f–317f lateral openbite, with anterior crowding, 305–309, 306f treatment alternatives for, 305 treatment goals for, 305 treatment progression for, 305–309, 307f–309f treatment results for, 309, 310f–312f patient, discussion in, 309–311 M Macroglossia, diagnostic criteria of, 149 Malocclusion class II, 71, 265, 266f–267f decompensation of a retreatment case presenting with, 113–120, 118f considerations of, 117 division 1 type, 110, 111f, 121f problem list, 116–117 treatment goals of, 117 treatment of, 117–120, 119f, 122f–123f class III, orthognathic camouflage with temporary anchorage devices for, 243–262 bimaxillary extrusion and single-dentition extrusion, 257–260 without TADs, 243–245, 244f–249f maxillary vertical development, 254–256 orthodontic extrusion stability, 260 single-dentition extrusion with TADs in mandible, 250–254, 250f–255f in maxilla, 254, 256f–259f Mandible i-station in, 43, 44f single-dentition extrusion with TADs in, 250–254, 250f–255f bite raisers and extrusion of upper anterior teeth, 254 extrusion of posterior teeth, 254 insertion of TADs, 250 Mandibular anterior crowding, 183–184, 186f

Mandibular buccal shelf screw, 29 Mandibular dentition intrusion, 57f Mandibular left second molar protraction, 293f Mandibular midline correction, 290f Mandibular molars distalization of, 200–202 diagnosis of, 200–201, 200f, 201t retention of, 202, 203f superimposition of, 202, 203f treatment plan of, 201 treatment progress of, 201, 202f treatment results of, 201, 202f intrusion, in openbite, 236f–237f, 237 MAPA. see Mini-implants assisted palatal appliances Maxilla i-station in, 43, 44f narrow, 65–67, 67f–68f single-dentition extrusion with TADs in, 254, 256f–259f vertical development, in class III malocclusion, 254–256 Maxillary bilateral molar distalization, 46, 50f, 56f Maxillary incisors, compromised, temporary anchorage devices in, 274–275, 274f–275f Maxillary i-station, 46, 51f Maxillary molars, distalization of, 197–200 diagnosis of, 197, 197f, 198t retention of, 199, 199f superimposition of, 199–200, 200f treatment plan of, 197–199, 198f treatment progress of, 197 treatment results of, 197–199, 199f Maxillary posterior area, TAD sites in, 25, 25f Mechanics, defined, 3 Mesial sliding appliance, 37–38, 37f–38f MGBM system, for class II nonextraction, 295–304 dual distal system and, 301–302, 302f–303f incisor retraction in, 297–301, 298f–302f upper molar distalization in, 295–296, 296f upper premolars and canines, retraction of, 296–297, 297f Midline deviations, 183 Mini-implant assisted retraction, distalization effect of, 16–17, 17f Mini-implant diameter, 31 Mini-implants anchorage, hybrid model with, 17–19, 18f–19f benefits of, 215 in buccal shelf area, 210f characteristics of, 211–213, 214f–218f in extraalveolar site, 209f–210f final considerations for, 215 indications for, 210–211, 211f–213f

325

326

Index

Mini-implants (Continued) infrazygomatic crest (IZC) area, 210f magnitude of the force applied, 215 optimal insertion sites for, 71–72 placement techniques for, 213 bone sites for, 21–28 buccal shelf, 213–214 buccal shelf region, 209f, 215 infrazygomatic crest, 208f, 213 three-dimensional evaluation of, 21–28 precautions of, 215 space closure mechanics with, 12, 13f Miniplates, 109, 110f Mini-implant-driven orthodontics, biomechanics principles in, 1–20 approaches for studying tooth movement in, 3 basic mechanical concepts in, 3–8 concept of equilibrium as, 8 couple as, 7–8, 7f–8f force as, 3, 4f force diagrams and vectors as, 4–6, 4f moment (torque) as, 6–7, 7f basic model for space closure in, 12–17, 13f–15f center of rotation in, 9, 10f equilibrium in orthodontics in, 8 estimating the center of rotation in, 10–12 mechanical factors affecting incisor retraction in, 17–19, 17t, 18f principle of equivalent force systems in, 8–9, 9f space closure mechanics with mini-implants, 12, 13f Mini-implants application of, 62, 64f ridge, for orthodontic anchorage, 267–274, 271f–273f in vertical alveolar ridge development, 278, 280f–281f Mini-implants assisted palatal appliances (MAPA), 61–70 appliance fabrication of, 62, 64f–65f clinical cases of, 62–67 asymmetrical cases, 67, 68f class II patient, 63–65, 66f class III growing patients, 62–63, 65f narrow maxilla, 65–67, 67f–68f mini-implant application of, 62, 64f surgical guide fabrication in, 61–62, 61f–63f Mini-implant-supported zygomatic miniplates, use of, 165–166, 165f Molars distalization, lower, anchorage of TADs for, 305–320 anterior openbite, 309–311, 313f–314f treatment progression for, 311, 314f–315f treatment results for, 311, 316f–317f lateral openbite, with anterior crowding, 305–309, 306f

Molars distalization, lower, anchorage of TADs for (Continued) treatment alternatives for, 305 treatment goals for, 305 treatment progression for, 305–309, 307f–309f treatment results for, 309, 310f–312f patient, discussion in, 309–311 Moment of the couple (MC), 7 Moment of the force (MF), 6–7 Moment (torque), 6–7, 7f Moment-to-force (M/F) ratios, 11–12 altering, 11–12, 12f point of force application, 11, 11f Multidisciplinary patients, with temporary anchorage devices, management of, 263–282 in compromised maxillary incisors, 274–275, 274f–275f endosseous dental implants, for missing posterior teeth, 265, 268f–270f mini-implants in vertical alveolar ridge development, 278, 280f–281f for preprosthetic space appropriation, 265, 266f–267f ridge mini-implants for orthodontic anchorage, 267– 274, 271f–273f skeletal anchorage in orthognathic surgery, 275, 276f–279f for space development for implant in congenitally missing lateral incisor, 263, 264f–265f Multipurpose implant (MPI), 150–151, 150f–151f possible complications of, 151 removal of, 151 surgical method for, 150–151, 151f Muscle exercises, openbite treatment and, 154 N Nance button, 71 Nickel-titanium (NiTi) springs, 73–74 Nonextraction, 197 O O-caps, 275 Occlusion, after space closure, 38, 39f Openbites, 149 anterior, 149, 156, 159f classification of, 149 problem list of, 160 treatment objectives of, 160 treatment plan of, 160 treatment results of, 160, 161f–162f treatment sequence of, 160 class II, progressive condylar resorption case, 132–142, 135f–139f considerations of, 138–139

Index

Openbites (Continued) problem list, 138 treatment goals, 138 treatment of, 139–142, 140f–144f skeletal, 221–242 biomechanics of molar intrusion in, 223–227, 224f–227f case report on, 227, 228f–231f mandibular molar intrusion in, 236f–237f, 237 through incisor extrusion with TADs, 237–241 case report on, 238–241, 238f–241f vertical control with palatal TADs, 232–237 case report on, 232–237, 232f–237f treatment, retention of, 154 Openbite appliance (OBA), new generation, 152–160 clinical application of, 153–154, 153f–154f clinical experience of, 154 fabrication of, 152–153 acrylic cap, 152–153 wire bending, 152, 152f retention of, 154 Openbite malocclusion, treatment and, 149–150 Orthodontic anchorage, ridge mini-implants for, 267–274, 271f–273f Orthodontic extrusion stability, 260 Orthodontic space closure, 35, 37f Orthognathic camouflage, with temporary anchorage devices, for class III malocclusion, 243–262 bimaxillary extrusion and single-dentition extrusion, 257–260 without TADs, 243–245, 244f–249f maxillary vertical development, 254–256 orthodontic extrusion stability, 260 single-dentition extrusion with TADs in mandible, 250–254, 250f–255f in maxilla, 254, 256f–259f Orthognathic surgery, skeletal anchorage in, temporary anchorage devices in, 275, 276f–279f Overbite, correction of, 265 Overjet, correction of, 265 P Pain, multipurpose implant and, 151 Palatal acrylic pad, 71 Palatal mini-implants, 30–31 extraalveolar mini-implants and, 30 risk factors for, 30–31, 30t Palatal screw insertion of, 35–38 selection of, 35–38

Palatal temporary anchorage devices, 196 aligner treatment using, 71–86 with Beneslider, strategies and clinical tips for, 72–73, 74f clinical considerations of, 80–83 clinical procedure and rationale of, 72–80 during distalization, 74–80, 76t, 78f–83f, 80t distalization and, simultaneous start of, 73–74, 75f–77f site of, 25, 25f Panoramic photographs, of mandibular deviation, 45, 49f, 52f, 55f posttreatment, 58f Partial anterior crossbite, 89 case summary of, 89, 91f diagnosis of, 89 extraoral analysis of, 89t intraoral analysis and functional analysis of, 90t problem list for, 90t smile analysis of, 90t treatment objectives of, 92t treatment options of, 89, 93f–98f treatment sequence and biomechanical plan, 92t Peclab screw kit, 207f, 212 Positron emission tomography (PET)-G bite, 61–62 Posterior teeth in bimaxillary extrusion without TADs, 245 missing, endosseous dental implants for, temporary anchorage devices in, 265, 268f–270f single-dentition extrusion with TADs in mandible, 254 Postsurgical swelling, multipurpose implant and, 151 Power arm–based space closure, 15f Preprosthetic space appropriation, temporary anchorage devices for, 265, 266f–267f Progressive condylar resorption case, class II openbite development, 132–142, 135f–139f considerations of, 138–139 problem list, 138 treatment goals, 138 treatment of, 139–142, 140f–144f Prosthetic-implantologic solution, 35, 36f Protruded upper teeth, 170, 197 diagnosis and case summary of, 173, 174f extraoral analysis for, 172, 174f final results of, 175, 178f–179f functional analysis for, 173 intraoral analysis for, 173 problem list of, 173 smile analysis for, 172–173 treatment objectives of, 173 treatment options of, 175

327

328

Index

Protruded upper teeth (Continued) treatment sequence and biomechanical plan for, 175, 176f treatment sequence of, 175, 177f Push-type mechanics, for edge to edge anterior occlusion, 184 Q Qualitative approach, for studying tooth movement, 3 Quantitative approach, for studying tooth movement, 3 Quasi-static system, 8, 8f R Rapid palatal expansion (RPE), 62–63 Restorative treatment, previous, complex interdisciplinary challenge compromised by, 120–123, 123f, 125f considerations of, 120 problem list, 120 treatment goals, 120 treatment of, 120–123, 126f–130f Resultant, 4 Retrognathic mandible, 154, 155f problem list of, 155 treatment objectives of, 156 treatment plan of, 156 treatment results of, 156, 158f treatment sequence of, 156, 156f–157f Ricketts’ Chart for Calculation of Force Magnitude, 153–154, 153f Ridge mini-implants for orthodontic anchorage, 267–274, 271f–273f placement techniques, 269 Rugae, T-Zone palatal posterior from, 72f S Sagittal split osteotomy, simultaneous mandibular advancement with, 113, 116f Second molar protraction, 283–294 Self-drilling screws, 211 Self-tapping screws, 211 Sequential plastic aligners, 72 Simple tipping, 10–11 Simultaneous mandibular advancement, 123 Simultaneous Upper Molar Distalizing System (SUMODIS) component, 295–296, 296f Single-dentition extrusion bimaxillary extrusion and, 257–260 with TADs in mandible, 250–254, 250f–255f bite raisers and extrusion of upper anterior teeth, 254 extrusion of posterior teeth, 254 insertion of TADs, 250 in maxilla, 254, 256f–259f

Skeletal Anchor System (SAS) plates, 109 Skeletal anchorage complex orthodontic problems managing with, 109–146 bimaxillary dental protrusion, decompensation of treatment case, 113–120, 118f considerations of, 117 final facial outcome of, 120, 124f problem list, 116–117 treatment goals of, 117 treatment of, 117–120, 119f, 122f–123f previous restorative treatment, 120–123, 123f, 125f considerations of, 120 problem list, 120 treatment goals, 120 treatment of, 120–123, 126f–130f progressive condylar resorption case class II openbite development, 132–142, 135f–139f considerations of, 138–139 problem list, 138 treatment goals, 138 treatment of, 139–142, 140f–144f reversing effects of failed growth modification/ camouflage in skeletal class II, 110–112, 113f–115f considerations of, 112 problem list, 110 treatment goals, 112 treatment of, 112 tooth surface loss, dental asymmetry and crowding, 126–129, 131f considerations of, 129 problem list, 129 treatment goals of, 129, 132f treatment of, 129, 133f–134f group A, mechanics, maximum, 110f in orthognathic surgery, temporary anchorage devices in, 275, 276f–279f palatal mini-implants and, 30–31 protocol of, 175 risk factors associated with, 29–32 site of placement, 29–30 buccal alveolar mini-implants/interradicular miniimplants, 29–30 success rates with, 29–32 Skeletal anterior openbite, 149 Skeletal mandibular retrognathism, magnitude of, 112 Skeletal openbites, 221–242 biomechanics of molar intrusion in, 223–227, 224f–227f case report on, 227, 228f–231f mandibular molar intrusion in, 236f–237f, 237

Index

Skeletal openbites (Continued) through incisor extrusion with TADs, 237–241 case report on, 238–241, 238f–241f vertical control with palatal TADs, 232–237 case report on, 232–237, 232f–237f Sliding mechanics, and loop mechanics, 44, 47f Space closure basic model for, 12–17, 13f–15f mechanics with mini-implants, 12, 13f Space development, for implant in congenitally missing lateral incisor, temporary anchorage devices for, 263, 264f–265f Spontaneous vertical eruption, of impacted third molar, 284–285, 285f Statics, 3 SUMODIS component. see Simultaneous Upper Molar Distalizing System (SUMODIS) component Superimposition, 51, 52f, 58f, 291f of distalization of mandibular molars, 202, 203f of maxillary molars, 199–200, 200f Surgical guide fabrication, 61–62, 61f–63f Surgically assisted rapid palatal expansion (SARPE), 65 T TADs. see Temporary anchorage devices Temporary anchorage devices (TADs), 23, 150, 283 application of, 109 in compromised maxillary incisors, 274–275, 274f–275f endosseous dental implants, for missing posterior teeth, 265, 268f–270f management of multidisciplinary patients with, 263–282 mini-implants in vertical alveolar ridge development, 278, 280f–281f orthognathic camouflage with, for class III malocclusion, 243–262 bimaxillary extrusion and single-dentition extrusion, 257–260 without TADs, 243–245, 244f–249f maxillary vertical development, 254–256 orthodontic extrusion stability, 260 single-dentition extrusion with TADs in mandible, 250–254, 250f–255f in maxilla, 254, 256f–259f in orthognathic surgery, 275, 276f–279f preoperative treatment planning of, 24–26 in buccal shelf area, 25–26, 26f in maxillary posterior area, 25, 25f in palate, 25, 25f for preprosthetic space appropriation, 265, 266f–267f ridge mini-implants for orthodontic anchorage, 267– 274, 271f–273f

Temporary anchorage devices (TADs) (Continued) root damage of, 23, 24f “safe zones” for, 23, 24f sites, 23, 24f for skeletal openbites, 221–242 biomechanics of molar intrusion in, 223–227, 224f–227f case report on, 227, 228f–231f mandibular molar intrusion in, 236f–237f, 237 through incisor extrusion with, 237–241 case report on, 238–241, 238f–241f vertical control with palatal, 232–237 case report on, 232–237, 232f–237f for space development for implant in congenitally missing lateral incisor, 263, 264f–265f Temporary Skeletal Anchorage Devices (TSAD), 183 Temporo-mandibular joint radiographs, 55f Third molar angulation, 285–286, 285f changes with second molar protraction, 284–286, 285f–286f horizontally impacted, 286–287, 287f–293f spontaneous mesioangular tipping of, 285–286, 286f uprighting, 283–294, 285f–286f Tipping controlled, 11 simple, 10–11 uncontrolled, 10–11 β-Titanium alloy, 120, 129 Tongue thrust swallowing, 149 Tooth movement approaches for studying, 3 managing of, with C-tube microplates, 181–194 clinical report of, 183–186, 186f–192f methods of, 183, 184f–185f types of, 10–11, 10f Transmissibility, principle of, 4 Transpalatal bar, in upper molar distalization, 295, 296f TSAD. see Temporary Skeletal Anchorage Devices U Uncontrolled tipping, 10–11 Unilateral premolar extraction, for asymmetrical malocclusion, 170 Unresponsive mandibular third molar, 285, 285f Upper anterior teeth, extrusion of, placement of bite raisers and, 254 Upper arch crowding, 166 diagnosis and case summary of, 166–168 extraoral analysis for, 166, 167f final result of, 170, 171f–172f functional analysis for, 166

329

330

Index

Upper arch crowding (Continued) intraoral analysis for, 166 problem list of, 168 smile analysis for, 166, 167f treatment objectives of, 168 treatment options of, 168 treatment sequence and biomechanical plan for, 168f–170f, 169 treatment sequence of, 170 Upper central incisor crowns, 123 Upper fixed appliances, 112, 117f Upper lateral incisors, missing, space closure for, 33–42 interdisciplinary aspects of, 38 canine, 38 first premolar, 38 orthodontic space closure for, 35, 37f palatal screw selection and insertion for, 35–38 prosthetic-implantologic solution for, 35, 36f therapy options to replace, 35, 36f Upper molar distalization, 295–296 asymmetric noncompliance, 71–86 in aligner treatment, 71 clinical considerations of, 80–83 clinical procedure and rationale of, 72–80 aligner start during distalization, 74–80, 76t, 78f–83f, 80t combine Beneslider and aligners, strategies and clinical tips, 72–73, 74f simultaneous start of aligner and distalization, 73–74, 75f–77f Upper teeth, protruded, 170 diagnosis and case summary of, 173, 174f extraoral analysis for, 172, 174f final results of, 175, 178f–179f

Upper teeth, protruded (Continued) functional analysis for, 173 intraoral analysis for, 173 problem list of, 173 smile analysis for, 172–173 treatment objectives of, 173 treatment options of, 175 treatment sequence and biomechanical plan for, 175, 176f treatment sequence of, 175, 177f V Vector addition, 4, 5f Vector composition, 4 Vector resolution, 4–6, 5f Vertical alveolar ridge development, mini-implants in, 278, 280f–281f Vertical eruption patterns, of impacted third molar, 284–285 W Wire bending, 152, 152f Z Zygomatic anchorage, 150–151 Zygomatic buttress, 150 Zygomatic miniplate supported molar distalization, 165–180 method description of, 165–166, 165f–166f supported openbite treatment, 147–164 multipurpose implant, 150–151, 150f–151f new generation openbite appliance, 152–160 openbite malocclusion and, 149–150

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