Surgery-First Orthodontic Management: A Clinical Guide to a New Treatment Approach [1st ed.] 978-3-030-18695-1;978-3-030-18696-8

Table of contents :
Front Matter ....Pages i-x
Introduction to Surgery-First Orthognathic Approach (SFOA) (Chai Kiat Chng, Narayan H. Gandedkar, Eric J. W. Liou)....Pages 1-6
Diagnosis and Treatment Planning of Surgery-First Orthognathic Approach (Chai Kiat Chng, Narayan H. Gandedkar, Eric J. W. Liou)....Pages 7-14
Biological Principles and Responses to Surgery-First Orthognathic Approach (Chai Kiat Chng, Narayan H. Gandedkar, Eric J. W. Liou)....Pages 15-21
Biomechanical Principles of Surgery-First Orthognathic Approach (Chai Kiat Chng, Narayan H. Gandedkar, Eric J. W. Liou)....Pages 23-35
Surgery-First Orthognathic Approach Treatment Protocol: Orthodontic Considerations (Chai Kiat Chng, Narayan H. Gandedkar, Eric J. W. Liou)....Pages 37-50
Surgical Management: Author’s Surgery-First Treatment Protocol (Chai Kiat Chng, Narayan H. Gandedkar, Eric J. W. Liou)....Pages 51-54
Management of Skeletal Class I Malocclusion with Surgery-First Orthognathic Approach (Chai Kiat Chng, Narayan H. Gandedkar, Eric J. W. Liou)....Pages 55-61
Management of Skeletal Class II Malocclusion with Surgery-First Orthognathic Approach (Chai Kiat Chng, Narayan H. Gandedkar, Eric J. W. Liou)....Pages 63-82
Management of Skeletal Class III Malocclusion with Surgery-First Orthognathic Approach (Chai Kiat Chng, Narayan H. Gandedkar, Eric J. W. Liou)....Pages 83-105
Management of Skeletal Asymmetry with Surgery-First Orthognathic Approach (Chai Kiat Chng, Narayan H. Gandedkar, Eric J. W. Liou)....Pages 107-123
Pre- and Post-surgery Patient Care Checklist and Patient Instruction (Chai Kiat Chng, Narayan H. Gandedkar, Eric J. W. Liou)....Pages 125-134
Potential Complications and Management of SFOA (Chai Kiat Chng, Narayan H. Gandedkar, Eric J. W. Liou)....Pages 135-143
Outcome Assessment of Surgery-First Orthognathic Approach (Chai Kiat Chng, Narayan H. Gandedkar, Eric J. W. Liou)....Pages 145-159
Future of Surgery-First Orthognathic Approach (Chai Kiat Chng, Narayan H. Gandedkar, Eric J. W. Liou)....Pages 161-174

Citation preview

Surgery-First Orthodontic Management A Clinical Guide to a New Treatment Approach Chai Kiat Chng Narayan H. Gandedkar Eric J. W. Liou

123

Surgery-First Orthodontic Management

Chai Kiat Chng • Narayan H. Gandedkar Eric J. W. Liou

Surgery-First Orthodontic Management A Clinical Guide to a New Treatment Approach

Chai Kiat Chng KK Women’s and Children’s Hospital Singapore

Narayan H. Gandedkar KK Women’s and Children’s Hospital Singapore

Eric J. W. Liou Chang Gung Memorial Hospital Taipei, Taiwan

ISBN 978-3-030-18695-1    ISBN 978-3-030-18696-8 (eBook) https://doi.org/10.1007/978-3-030-18696-8 © Springer Nature Switzerland AG 2019 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

Dedication from Dr. Gandedkar: To my parents, Aayi and Appa, ‘I never knew of the love and sacrifices you made as parents, until I became one myself’. To my wife, Krizanne, a gorgeous person inside-and-out and a true soulmate, and our two lovely sons, Aryan and Ayush, who make every day of my life ‘une vie amusante’. Dedication from Dr. Chai Kiat Chng: To my beloved parents, for your unconditional love and support, I am eternally grateful.

Contents

1 Introduction to Surgery-First Orthognathic Approach (SFOA) ����������   1 1.1 Introduction����������������������������������������������������������������������������������������   1 1.2 Overview of Surgery-First Orthognathic Approach (SFOA)��������������   1 1.3 Revival of Surgery-First Orthognathic Approach ������������������������������   4 1.4 Comparison of Conventional and Surgery-First Orthognathic Approach����������������������������������������������������������������������   5 1.5 Conclusion������������������������������������������������������������������������������������������   6 References����������������������������������������������������������������������������������������������������   6 2 Diagnosis and Treatment Planning of Surgery-First Orthognathic Approach����������������������������������������������������������������������������   7 2.1 Introduction����������������������������������������������������������������������������������������   7 2.2 Orthodontic and Surgical Considerations: Case Selection and Guidelines ������������������������������������������������������������������������������������������   7 2.2.1 Orthodontic-Driven����������������������������������������������������������������  10 2.2.2 Surgery-Driven������������������������������������������������������������������������  10 2.2.3 One Patient Two Problem Concept ����������������������������������������  10 2.3 Conventional Jaw Surgery Planning: Paper Surgery and Model Surgery������������������������������������������������������������������������������������  10 2.4 3D Virtual Surgical Planning and 3D Splint Fabrication��������������������  13 2.5 Conclusion������������������������������������������������������������������������������������������  14 References����������������������������������������������������������������������������������������������������  14 3 Biological Principles and Responses to Surgery-First Orthognathic Approach����������������������������������������������������������������������������  15 3.1 Introduction����������������������������������������������������������������������������������������  15 3.2 Regional Acceleratory Phenomenon��������������������������������������������������  15 3.2.1 Systemic Acceleratory Phenomenon (SAP)���������������������������  18 3.3 Osteotomy- and Corticotomy-Assisted Tooth Movement ������������������������������������������������������������������������������������������  18 3.4 Surgery-First Orthognathic Approach’s Molecular Response������������  19 3.5 Conclusion������������������������������������������������������������������������������������������  20 References����������������������������������������������������������������������������������������������������  20

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4 Biomechanical Principles of Surgery-­First Orthognathic Approach������  23 4.1 Introduction����������������������������������������������������������������������������������������  23 4.2 Six Degrees of Freedom (6DoF)��������������������������������������������������������  23 4.2.1 Natural Head Position: 2D and 3D ����������������������������������������  24 4.3 Considerations of Translational (Sagittal, Transverse, Vertical) and Rotational Envelopes (Pitch, Roll, and Yaw) ������������������������������  25 4.3.1 Virtual Surgical Planning��������������������������������������������������������  28 4.4 Conclusion������������������������������������������������������������������������������������������  34 References����������������������������������������������������������������������������������������������������  34 5 Surgery-First Orthognathic Approach Treatment Protocol: Orthodontic Considerations����������������������������������������������������������������������  37 5.1 Introduction����������������������������������������������������������������������������������������  37 5.2 Pre-surgical Orthodontics ������������������������������������������������������������������  37 5.2.1 Orthodontic Appliances (Brackets and Arch Ligation)����������  38 5.3 Pre-surgical Preparation����������������������������������������������������������������������  44 5.3.1 Determination of Transitional Occlusion��������������������������������  44 5.3.2 Surgical Splint Fabrication, Intermaxillary Fixation��������������  47 5.4 Post-surgery in Surgery-First Orthognathic Approach ����������������������  48 5.4.1 Post-surgical Orthodontic Considerations������������������������������  48 5.4.2 Post-surgical Orthopaedic Management, i.e. Chin Cup Therapy����������������������������������������������������������������������������  48 5.5 Conclusion������������������������������������������������������������������������������������������  49 References����������������������������������������������������������������������������������������������������  50 6 Surgical Management: Author’s Surgery-­First Treatment Protocol������  51 6.1 Introduction����������������������������������������������������������������������������������������  51 6.2 Type of Surgery with Indications, Complications, Considerations and Stability with the Type of Surgery����������������������  52 6.3 Conclusion������������������������������������������������������������������������������������������  54 References����������������������������������������������������������������������������������������������������  54 7 Management of Skeletal Class I Malocclusion with Surgery-First Orthognathic Approach����������������������������������������������������  55 7.1 Introduction����������������������������������������������������������������������������������������  55 7.2 Skeletal Class I Malocclusion SFOA Treatment Guidelines��������������  55 7.3 Case Report����������������������������������������������������������������������������������������  57 7.3.1 Treatment Objectives��������������������������������������������������������������  57 7.3.2 Surgical Plan ��������������������������������������������������������������������������  57 7.3.3 Treatment Progress ����������������������������������������������������������������  58 7.4 Conclusion������������������������������������������������������������������������������������������  61 8 Management of Skeletal Class II Malocclusion with Surgery-First Orthognathic Approach����������������������������������������������������  63 8.1 Introduction����������������������������������������������������������������������������������������  63 8.2 Treatment of Various Skeletal Class II Cases ������������������������������������  66 8.3 Conclusion������������������������������������������������������������������������������������������  81

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9 Management of Skeletal Class III Malocclusion with Surgery-First Orthognathic Approach����������������������������������������������������  83 9.1 Introduction����������������������������������������������������������������������������������������  83 9.2 SFOA Treatment Guidelines in Three Dimensions Based on the Degree of Complexity ��������������������������������������������������  83 9.3 Case Presentation��������������������������������������������������������������������������������  83 9.3.1 Treatment��������������������������������������������������������������������������������  84 9.4 Conclusion������������������������������������������������������������������������������������������ 105 10 Management of Skeletal Asymmetry with Surgery-First Orthognathic Approach���������������������������������������������������������������������������� 107 10.1 Introduction�������������������������������������������������������������������������������������� 107 10.2 Case 1: A Maxillary Occlusal Cant Extending Anteriorly to Posteriorly: Its Influence on MMC and on Subsequent Treatment Planning �������������������������������������������������������������������������� 108 10.3 Case 2: Differential Anterior and Posterior Region Maxillary Occlusal Cant: Its Influence on MMC and on Subsequent Treatment Planning�������������������������������������������������������� 112 10.4 Conclusion���������������������������������������������������������������������������������������� 123 References���������������������������������������������������������������������������������������������������� 123 11 Pre- and Post-surgery Patient Care Checklist and Patient Instruction ������������������������������������������������������������������������������������ 125 11.1 Introduction�������������������������������������������������������������������������������������� 125 11.2 Pre- and Post-surgery Checklist: Category, Conditions, Assessment Tools, and Management Plan���������������������������������������� 125 11.2.1 Systemic Conditions, Medication/Anaesthesia Clearance���128 11.2.2 Psychological Assessment�������������������������������������������������� 128 11.2.3 Mental/Cognitive Assessment �������������������������������������������� 129 11.2.4 Social Support �������������������������������������������������������������������� 129 11.2.5 Postoperative Nutrition (Fluid and Electrolyte Balance)���� 130 11.2.6 Patient’s Informed Consent ������������������������������������������������ 130 11.2.7 Postoperative Pain Management ���������������������������������������� 130 11.2.8 Oral Prophylaxis Requirements/Guidance�������������������������� 131 11.2.9 Orthodontic and Jaw Surgery���������������������������������������������� 131 11.3 Instructions for Patients and Care Givers: Dos and Don’ts�������������� 131 11.4 Conclusion���������������������������������������������������������������������������������������� 132 References���������������������������������������������������������������������������������������������������� 133 12 Potential Complications and Management of SFOA������������������������������ 135 12.1 Introduction�������������������������������������������������������������������������������������� 135 12.2 Orthodontist-Related Complications and Management�������������������� 135 12.2.1 Pre-surgery Phase���������������������������������������������������������������� 135 12.2.2 Surgery Phase���������������������������������������������������������������������� 137 12.2.3 Post-surgery Phase�������������������������������������������������������������� 140 12.3 Surgery-Related Complications and Management �������������������������� 140 12.4 Conclusion���������������������������������������������������������������������������������������� 143 References���������������������������������������������������������������������������������������������������� 143

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13 Outcome Assessment of Surgery-First Orthognathic Approach ���������� 145 13.1 Introduction�������������������������������������������������������������������������������������� 145 13.2 Treatment Duration of SFOA Versus Conventional Orthognathic������ 145 13.2.1 Orthodontic Treatment Difficulty Level: Minimal to Moderate ������������������������������������������������������������������������ 154 13.2.2 Orthodontic Treatment Difficulty Level: Severe���������������� 154 13.3 Stability of SFOA Versus Conventional Jaw Surgery ���������������������� 155 13.4 Quality of Life Outcomes and Psychological Status for SFOA�������� 155 13.5 SFOA: Evidence-Based Practice������������������������������������������������������ 156 13.6 Conclusion���������������������������������������������������������������������������������������� 157 References���������������������������������������������������������������������������������������������������� 158 14 Future of Surgery-First Orthognathic Approach ���������������������������������� 161 14.1 Introduction�������������������������������������������������������������������������������������� 161 14.2 3D Image Acquisition and Diagnosis ���������������������������������������������� 161 14.3 Virtual Surgical Planning (VSP) ������������������������������������������������������ 167 14.4 ‘Tools of Transfer’ for Surgery Planning������������������������������������������ 169 14.4.1 CAD/CAM Splints with Extra-Oral Bone-Borne Support (EOBS)������������������������������������������������������������������ 169 14.5 3D Printing/Rapid Prototyping in Surgery �������������������������������������� 170 14.6 Augmented Real-Time and Virtual Surgical Navigation������������������ 170 14.7 Conclusion���������������������������������������������������������������������������������������� 173 References���������������������������������������������������������������������������������������������������� 173

1

Introduction to Surgery-First Orthognathic Approach (SFOA)

We are not makers of history. We are made by history. —Martin Luther King, Jr.

1.1

Introduction

Surgery-first orthognathic approach is an emerging science whose roots can be traced back to the 1960s. An overview of surgery-first orthognathic approach shows the evolution of SFOA. ‘Jaw surgery’ pioneers and predecessors thought process and ideas are what shaped surgery-first orthognathic approach (SFOA). What was their approach, and what made the technique catch the attention of the ‘practitioners of the day’ and subsequently descended into oblivion for a considerable period of time? SFOA found a revival itself from a profound relying on ‘heuristic judgement’ of the early resurrection days to a more concrete epistemological method in the light of modern time’s evolved armamentarium and evidence.

1.2

 verview of Surgery-First Orthognathic O Approach (SFOA)

Conventional jaw surgery did originate sometime in the eighteenth century (1849) [1–3] when an American oral surgeon, Simon Hullihen (considered as the father of oral surgery), first performed jaw surgery to correct a prognathic mandible. It took another century (1957) for conventional jaw surgery to become a mainstay treatment for the correction of dentofacial deformity when two Austrian oral surgeons, Richard Trauner and Hugo Obwegeser, introduced sagittal split osteotomy, which then marked the foundation of the modern era of jaw surgery [4].

© Springer Nature Switzerland AG 2019 C. K. Chng et al., Surgery-First Orthodontic Management, https://doi.org/10.1007/978-3-030-18696-8_1

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1  Introduction to Surgery-First Orthognathic Approach (SFOA)

Pre-surgical orthodontics and surgery-related orthodontics, in general, were not deemed important components on the overall management of the ortho-orthognathic patient. Jaw surgery was performed either before orthodontic treatment or after the removal of orthodontic appliances [5]. Jaw surgery was carried out without presurgical orthodontics (Fig.  1.1), which unwittingly gave rise to surgery-first approach. Given the circumstances and several factors as enumerated below, the authors cogitate that the following factors were some of the reasons that discouraged orthodontists and oral surgeons to work in tandem as far as jaw surgery cases were involved. 1. Cemented (cast gold) splints impeded the possibility of tooth movement post-­ surgery; hence, less emphasis was placed on the correction of malocclusion, and orthodontists role in jaw surgery was primarily (and restricted) in providing a surgical splint that represented predetermined post-surgery occlusion [6]. 2. Intermaxillary fixation was kept in place for a prolonged period of time [7]. 3. Acid-etching technique and bonding agents were in the inception stages [8, 9]. 4. Relying on handmade bands and metallic straps for brackets that involved lengthy appointment time, the mutual belief that orthodontic appliances were too fragile to stabilize jaw fragments leads to the removal of pre-surgery appliances (if any) and placement of the arch bars for surgery. Also, placing a new set of orthodontic appliances after surgery was not only an expensive undertaking but was impractical too [10]. 5. There was a lot of time spent customizing and bending arch wires as superelastic wires were still in the experimental stage, and were not widely available [11]. 6. There was a lack of communication between oral surgeon and orthodontist, as each fraternity believed working independently of each other. This culture of working in silos led the orthodontist and oral surgeon to remain unaware of each other’s field advancements [10, 12, 13]. Our pioneers have done a remarkable job and have achieved a commendable feat in the field of ‘surgical orthodontics’ despite the scarcity of resources at the time (antibiotics, local or general anaesthetics, superelastic wires, and bonding agents were either lacking or not available). In order to overcome the failure rates of those jaw surgeries that did not accompany pre-surgical orthodontics, there was more attention paid to the orthodontics part of the surgical case. Also, with the advent of considerable surge in orthodontic materials, thanks to the ‘technology boom’ of the 1970s [11], orthodontics saw a new lease of life with emphasis on technology-­driven treatment approach; this change favoured orthognathic-orthodontics management. Worms et al. stated that orthodontics-first concept must be rigorously employed to all jaw surgery cases where sagittal, vertical, and transverse discrepancies were not possible to be managed by orthodontics alone and emphasized that optimal surgical repositioning of the maxillo-mandibular complex is only possible following the elimination of all impeding dental compensation prior to surgery [13, 14]. Subsequently, post-1970, comprehensive orthodontic treatment or commonly addressed as ‘orthodontic decompensation’ became an integral component of the jaw surgery management. Many scientific papers have been written since where an

1963

1960

Poulton et al

Mandibular set-back

Fig. 1.1  Surgery-first orthognathic approach timeline Recommended orthodontics just before surgery Facial asymmetry cases were treated with SFOA

Villegas et al Wang et al Kao et al

2010 2010 2010

SFOA Skeletal stability was comparable to conventional surgery

Transverse dental corrections do not require pre-surgical orthodontics

Significant reduction of treatment time.

Yang et al

Sugawara et al

2017

Nagasaka et al

2000-2010

Orthodontic treament easier to perform post-surgery

Huang et al

Choi JW

2015 2016

Yu et al

2015

2010

2010

Lee

1994

SFOA could be done

Anterior open bite managed with SFOA

Minimal orthodontic treatment before the surgery proposed

2009

Behrman et al

1988

1970-2000

Epker and Fish

Bell et al

1977

1973

2011-Present

Long term outcome of SFOA and conventional surgery compared Quality of life significantly improved in SFOA cases compared to conventional surgery A Systematic Review and Meta-Analysis on SFOA

SFOA is regarded as an ideal and valuable

Hernandez et al Emphasise is laid on diagnosis and case selection Villegas et al Facial asymmetry cases were treated with SFOA

2011

‘Transitional occlusion ‘is established post-surgery

Liou et al

2011

1.2  Overview of Surgery-First Orthognathic Approach (SFOA) 3

4

1  Introduction to Surgery-First Orthognathic Approach (SFOA)

oral surgeon or plastic surgeon teamed with orthodontists managed jaw surgery patients. Subsequently, the term ‘surgical orthodontics’ was coined. ‘Surgical orthodontics’ saw advancements in three distinct areas: • On a technique front: Pre-surgical orthodontics to eliminate dental compensation became more refined. The development of better rigid internal fixation techniques with same-day surgery shortened treatment phases and improved stability of postsurgical position. • On a technological front: State-of-the-art navigation systems coupled with computer-­ aided designed/computer-aided manufactured splints for surgical transfer of virtual jaw planning made ‘surgical orthodontics’ more precise and accurate. • On a communication and education front: Many dental conferences are now organized with dedicated jaw surgery session. Dental schools have included jaw surgery curriculum for both orthodontic and surgery students with joint clinics in specialty-based hospitals. Where such facilities are unavailable, novel ways of education includes teleconferencing for combined clinics for residents. Didactics in these schools emphasises the value of multidisciplinary team-based approach with patient-centric treatment plan and comprehensive management.

1.3

Revival of Surgery-First Orthognathic Approach

Conventional jaw surgery has many restrictions and limitations which have led practitioners to seek a newer paradigm that will essentially address the caveats of conventional jaw surgery, as enumerated below, and in Table 1.1. 1. Pre-surgical orthodontics is a prerequisite for conventional jaw surgery for arch coordination and overcomes dental compensation to reveal true extent of skeletal deformity. 2. Pre-surgical orthodontics would take a considerably long period of time (12–18 months) which is a significant drawback for patients. 3. There is a worsening of facial profile before surgery which could cause negative impact on the perception of patients’ quality of life. Following the commentary of Dr William Bell that conventional jaw surgery is ‘too complicated, too invasive, too-time consuming, and too unpredictable’, a paradigm shift would be necessary to ensure jaw surgery to become more efficient, affordable, predictable, and convenient with a focus on utilizing advanced three-­ dimensional imaging technology and empirical evidence to mitigate the effects of pre-surgical orthodontic treatment. SFOA has been around for more than four decades, but the emphasis was sporadic in approach, until Lee et  al., in 1994 [15], showed that early correction of skeletal and soft tissue deformities would make correction of misaligned teeth easier by establishing a relatively normal (Class I) skeletal and soft tissue environment post-surgically. However, the benefits of SFOA, as described by Lee et al., did not

1.4  Comparison of Conventional and Surgery-First Orthognathic Approach

5

accompany substantial clinical evidence to prove the claims. Subsequently, nearly after a decade since Lee et al.’s publication, SFOA regained interest when Nagasaka et al. performed SFOA in a Class III individual. Consequently various groups, especially in the Asia-Pacific region, published case series, prospective studies, systematic reviews, and meta-analysis in the past years which have led to a new paradigm shift in the treatment approach as far as treating jaw deformities are concerned.

1.4

 omparison of Conventional and Surgery-First C Orthognathic Approach (Table 1.1)

Table 1.1  Table comparing salient features of ‘SFOA’ and ‘conventional jaw surgery’ SFOA Salient features Pre-surgery orthodontic 1–4 weeks treatment Stages involved Three stages • Pre-surgery orthodontics • Jaw surgery • Post-surgery orthodontics 12–18 months Post-surgery orthodontic treatment time Impact on facial profile Immediate improvement Post-surgical stability

Yet to be evaluated in detail

Quality of life: self-esteem, body image, level of satisfaction Early elimination of soft and hard tissue hindrances

Significant benefits with the surgery-first approach

Patient satisfaction rate

Surgery option

Possible to eliminate imbalances in the beginning of treatment due to establishment of proper maxillomandibular relationship, thereby allowing efficient dental correction High patient satisfaction rate is associated with improved cooperation during postoperative orthodontics Surgery can be opted based according to patients’ will

Overall treatment time 1–1.5 years Patient selection criteria Critical for the success of treatment as the baseline dental relation is unable to guide the post-surgery occlusion. The orthodontist experience in assessing and predicting accurate post-surgery tooth movement plays a vital role

Conventional jaw surgery 12–18 months Two stages • Jaw surgery • Post-surgery orthodontics 6–12 months Potential aggravation led by worsening of profile before surgery No immediate post-surgical instability Negative impact on the perception of patients’ quality of life Not possible; in fact, worsens due to ensued decompensation mechanism Patients cannot appreciate the immediate corrections due to pre-surgical orthodontics phase Surgery timing can’t be chosen as the patient has to wait until pre-surgical decompensation is completed 3–4 years Non-critical, complex cases can be managed with appropriate pre-surgical decompensation stage

6

1  Introduction to Surgery-First Orthognathic Approach (SFOA)

1.5

Conclusion

Jaw surgery is coming into a new era of management where patients and practitioners both benefit. As Thomas S.  Kuhn, who coined the term ‘paradigm shift’, describes ‘paradigm shift’ as an undeniable discovery that is thoroughly undoing the accepted knowledge and beliefs [16]; and so is SFOA, which has poised itself to undo the previous conventions with which we have approached jaw surgery management. Dr William Bell’s statement on paradigm shift in jaw surgery sums up what is in store. ‘They won’t buy that stuff anymore’. ‘The old ways of doing business are over’. ‘We need to make new alliances’. ‘Others are waiting to seize our turf’. [17]—Dr. William Bell on ‘Paradigm Shifts in Jaw Surgery’

References 1. Poulton D, Ware W. The American academy of oral roentgenology joins our journal. Oral Surg Oral Med Oral Pathol. 1959;12:389–90. 2. Aziz SR. Simon P. Hullihen and the origin of orthognathic surgery. J Oral Maxillofac Surg. 2004;62:1303–7. 3. Hayward J. The legacy of Simon P. Hullihen. J Hosp Dent Pract. 1976;10:73–4. 4. Trauner R, Obwegeser H. The surgical correction of mandibular prognathism and retrognathia with consideration of genioplasty: part I. Surgical procedures to correct mandibular prognathism and reshaping of the chin. Oral Surg Oral Med Oral Pathol. 1957;10:677–89. 5. Huang C, Hsu S, Chen Y-R. Systematic review of the surgery-first approach in orthognathic surgery. Biom J. 2014;37:184. 6. Ottolengui R. A friendly criticism of Dr. Angle’s proposed technique in surgical correction of mandibular protrusion. Dental Cosmos. 1903;45:454–7. 7. Juniper R, Awty M. The immobilization period for fractures of the mandibular body. Oral Surg Oral Med Oral Pathol. 1973;36:157–63. 8. Gwinnett A, Matsui A. A study of enamel adhesives: the physical relationship between enamel and adhesive. Arch Oral Biol. 1967;12:1615–IN46. 9. Buonocore M, Matsui A, Gwinnett A. Penetration of resin dental materials into enamel surfaces with reference to bonding. Arch Oral Biol. 1968;13:61–IN20. 10. Proffit WR, White RP. Development of surgeon-orthodontist interaction in orthognathic surgery. Semin Orthod. 2011;17:183–5. 11. Kusy RP. Orthodontic biomaterials: from the past to the present. Angle Orthod. 2002;72:501–12. 12. Proffit WR, White RP Jr. Combined surgical-orthodontic treatment: how did it evolve and what are the best practices now? Am J Orthod Dentofacial Orthop. 2015;147:S205–S15. 13. Biederman W.  The orthodontist's role in resecting the prognathic mandible. Am J Orthod. 1967;53:356–75. 14. Worms FW, Isaacson RJ, Michael ST. Surgical orthodontic treatment planning: profile analysis and mandibular surgery. Angle Orthod. 1976;46:1–25. 15. Lee R. The benefits of post-surgical orthodontic treatment. Br J Orthod. 1994;21:265–74. 16. Kuhn TS, Hawkins D. The structure of scientific revolutions. Am J Physiol. 1963;31:554–5. 17. Assael LA. The biggest movement: orthognathic surgery undergoes another paradigm shift. Philadelphia, PA: WB Saunders; 2008.

2

Diagnosis and Treatment Planning of Surgery-First Orthognathic Approach

Diagnosis is not the end, but the beginning of practice. —Martin H. Fischer (1879–1962)

2.1

Introduction

Diagnosis and treatment planning forms the basis of successful treatment planning. The chapter entails orthodontic and surgical considerations with case selection and guidelines. Both conventional and 3D surgical planning are discussed. Careful consideration of specific landmarks and planes leads to successful planning and execution of maxilla-mandibular complex deformity. Emphasis is laid on the understanding and visualizing of the post-surgery ‘transitional occlusion’. Further, the transitional occlusion could be transpired into final occlusion in the post-surgery phase of orthodontic treatment.

2.2

 rthodontic and Surgical Considerations: Case O Selection and Guidelines

Surgery-first orthognathic approach (SFOA) is fast becoming an accepted modality as part of jaw surgery and involves meticulous treatment planning and execution. Orthodontists play a pivotal role from the beginning and, together with the surgeon, perform patient evaluation and data collection (photographs, study models, and radiographs). Further, they perform the ‘mock surgery’ either by conventional method (paper surgery and model surgery) or 3D-assisted method (3D composite modelling and stereolithography) to facilitate the fabrication of a surgical bite splint. The surgical bite splint will guide the surgeon to execute the surgery as planned based on the earlier surgical planning. Figure 2.1 explains the routine workflow of SFOA. © Springer Nature Switzerland AG 2019 C. K. Chng et al., Surgery-First Orthodontic Management, https://doi.org/10.1007/978-3-030-18696-8_2

7

8

2  Diagnosis and Treatment Planning of Surgery-First Orthognathic Approach SFOA: Diagnosis and treatment planning

Data Gathering

Pre-surgical Assessment

Envelope of Discrepancy

Jaw Surgery

Orthodontics alone

Distraction Osteogenesis

Transitional occlusion

Case selection criteria

Mild or no ortho treatment

Moderate to severe

Sagittal

Treatment plan

Transverse

Vertical

Dental consideration

Extraction

Non-extraction

Skeletal consideration

Single Jaw

Double Jaw

Fig. 2.1  Routine workflow of surgery-first orthognathic approach

For beginners, cases with minimal dental discrepancies, in sagittal, vertical, and transverse planes, could be ideal cases to start with for SFOA. Some clinical examples would be: • In sagittal plane—mild proclination or retroclination of teeth • In transverse plane—minimal posterior crossbite or absence of a collapsed bite • In the vertical plane—mild curve of Spee with no significant deep bite or open bite More complex cases can be undertaken by an experienced practitioner for SFOA. Several factors are to be taken into consideration, such as: • Pre-surgical complexities (skeletal, dental, and soft tissue) • Orthodontic treatment mechanics (pre- and post-surgical) • Transitional occlusion

2.2  Orthodontic and Surgical Considerations: Case Selection and Guidelines

9

The flow chart in Fig. 2.2 explains the SFOA treatment guidelines in the form of sagittal, vertical, and transverse planes, along with the type of skeletal and dental considerations. The flow chart assists in formulating a transitional occlusion for the malocclusion to be treated simply with orthodontics post-surgery. The flow chart also explains which type of surgery is best suited for the resolution of skeletal conditions along with recommendations of extraction or non-extraction approach with emphasis on post-surgery considerations for the orthodontist. SFOA can be carried out by two different approaches: • Orthodontic-driven (see Sect. 2.2.1) • Surgery-driven (see Sect. 2.2.2)

Skeletal protusion + dental proclination

All four first premolar extraction + Bimaxillary set-back Jaw surgery, maxillary anterior segmental osteotomy

Skeletal protrusion + No dental proclination

Non-extraction + Bimaxillary set-back Jaw surgery

Class I Bimaxillary proclination

Sagittal

Class II

Class III

Protruded maxilla + normal mandible

Le Fort I set-back or Upper first premolar extraction + maxillary anterior segmental osteotomy

Protuded maxilla + Retruded mandible

Le Fort set-back+ BSSO advancment

moderate retroclined lower + crowded lower incisors

segmental osteotomy + BSSO set-back

Proclined maxillary incisors

Le Fort I osteotomy with clockwise rotation + BSSO set-back

severe retroclined and crowded lower incisors

Skeletal cross bite ≤ molar width

Lower first premolar extraction + anterior segmental osteotomy + BSSO set-back,

Set-up occlusion in Class I molar relation + Positive overjet

Consider genioplasty for chin augmentation

Set-up occlusion in Class I molar relation Or Class II in cases of upper first premolar extraction

consider creation of large positive overjet for correction of retrcolined lower incisors

Set-up occlusion in Class I relationship

Align lower incisors utilizing the large overjet

Set-up occlusion in Class III relationship + large positive overjet

Align lower incisors utilizing the large overjet

To correct crossbite postoperatively

Cross bite SFOA Treatment Guidelines

transverse

Scissors Bite

Class II

Skeletal cross bite > molar width

3-piece Le Fort I osteotomy of the maxilla.

Skeletal scissor bite > molar width

Consider SARPE

moderate to deep mandibular curve of Spee

Anterior open bite

Set-up occlusion within the tooth movement envelope

BSSO advancement

Set-up occlusion Edge-to-edge incisor and establish posterior disocclusion

Lower anterior segmental intrusion

Set-up occlusion in Class I relationship

Differential impaction of maxilla with clockwise rotation + BSSO advancement

Set-up occlusion in Class I relationship

Consider using TPA to correct bite postoperatively

Intrude anterior teeth and allow eruption of posterior teeth

Intrude posterior teeth, consider TAD’s

Vertical moderate to deep mandibular curve of Spee

Class III

Anterior open bite

Anterior segmental osteotomy

Differential impaction of maxilla with clockwise rotation + BSSO setback

Set-up occlusion in Class I relationship

Set-up occlusion in Class I relationship

lower incisors intruded + upper incisor extruded

Intrude posterior teeth, consider TAD’s

Fig. 2.2  Flow chart explains the SFOA treatment guidelines in the form of sagittal, vertical, and transverse planes

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2  Diagnosis and Treatment Planning of Surgery-First Orthognathic Approach

2.2.1 Orthodontic-Driven This encompasses correction of skeletal problems with jaw surgery and dental problems using skeletal anchorage system. This aforementioned technique was popularized by Sugawara and team of Japan and eventually named it as ‘Sendai surgery first’ (SSF) [1, 2]. The basic tenets of SSF lie in controlling the post-surgical orthodontic biomechanics with the help of skeletal anchorage system. The proponents of this approach claim that application of SAS post-surgery enables control of the entire dentition, including the three-dimensional control of bimaxillary molars, and facilitates correction of a wide range of complexities. However, some of the drawbacks of this technique are (1) overreliance on SAS, (2) post-surgical complex orthodontic tooth movement, (3) added cost of SAS, and (4) additional surgical intervention for removal of SAS post-treatment.

2.2.2 Surgery-Driven The proponents of this technique espouse that both skeletal and complex dental problems are corrected with jaw surgery thus allowing only orthodontically treatable malocclusion to persist post-surgery in the form of transitional malocclusion such that routine orthodontics biomechanics is employed to correct the malocclusion utilizing regional acceleratory phenomenon [3–8].

2.2.3 One Patient Two Problem Concept SFOA is a ‘one patient two problem concept’, wherein the skeletal and dental are two separate problems which need to be addressed in one patient. The skeletal complexities are corrected via jaw surgery, and a ‘transitional occlusion’ is set up such that the second problem, i.e. the dental problem, is managed with conventional orthodontic treatment. Further, the ‘transitional occlusion’ is transfigured into a final occlusion to establish a relationship amongst all teeth that are appropriately placed in the jaw arcades and display a functional anatomic relationship to each other. Ultimately, the dentition should exhibit a cusp-fossa relationship, to ensure structural durability, functional efficiency, and aesthetic harmony. The prerequisites of transitional occlusion and its importance, along with biomechanical principles of SFOA protocol, are explained in detail in Chaps. 4 and 5.

2.3

 onventional Jaw Surgery Planning: Paper Surgery C and Model Surgery

‘Paper and model surgery’ offers a simple and reliable method of assessing and formulating the treatment plan of a dentofacial deformity using routinely available tools of assessment such as photographs, study models, and radiographs (cephalographs). Meticulous evaluation of specific landmarks and planes can lead to

2.3  Conventional Jaw Surgery Planning: Paper Surgery and Model Surgery

11

efficient planning and execution leading to the correction of maxilla-mandibular complex deformity. The diagnostic information obtained from clinical findings and radiographic assessments are integrated in the ‘paper surgery’ to establish a surgical plan. Further, the ‘paper surgery’ is emulated on a face-bow transfer, articulatormounted study models in ‘model surgery’ for surgical splint creation. The treatment plan, when using 2D data, is essentially a composite of clinical evaluation and cephalometric (both lateral and postero-antero cephalograph) assessment using Schwarz’s ‘gnathic profile field (GPF)’. GPF is a simple yet efficient clinical appraisal of a patient’s maxillofacial profile pattern by observing patients in their profile view. Also, ‘rule of thirds’ is applied for the evaluation and correction of face. ‘Rule of thirds’ divides the face horizontally into thirds with reference lines drawn at the hairline, eyebrows, base of nose, and chin (Fig. 2.3).

Fig. 2.3  Figure showing gnathic profile field, rule of thirds, and preclinical measurement chart used for the initial assessment of SFOA cases. GPF essentially involves certain landmarks which are enumerated below: nasion (Na), the junction of the nasal and frontal bones at the most posterior point on the curvature of the bridge of the nose; orbitale (Or), a point midway between the lowest point on the inferior margin of the two orbits; pogonion (Pg), the most anterior point on the contour of the chin; porion (Po), the midpoint of the upper contour of the external auditory canal (anatomic porion) or a point midway between the top of the image of the left and right ear rods of the cephalostat (machine porion); subnasale (Sn), it is the transition point between the nose and the upper lip. It is the projection of hard tissue A point; Frankfort horizontal plane (FHP), a line connecting Po to Or; OVL orbitale vertical line; NVL nasion vertical line

12

2  Diagnosis and Treatment Planning of Surgery-First Orthognathic Approach

Skeletal movements of jaw surgery are planned by analysing certain soft tissue landmarks. Schwarz used these landmarks for photographic and clinical assessment. We have adapted them to lateral cephalograph for the planning of jaw surgery. Also, postero-anterior (PA) cephalographs are used to assess and plan jaw surgery for the correction of skeletal asymmetry. ‘GPF’ and ‘rule of thirds’ provide simple and practical method of clinical evaluation of the soft tissue relationship. The surgical splint produced using this method involves the orthodontist in the splint fabrication, so that the orthodontist can control all the variables. Performing the ‘paper surgery’ and ‘model surgery’ aids the surgeon to emulate the plan and to preview the final outcome (Fig. 2.4). The aforementioned conventional jaw surgery approach poses several drawbacks at various levels, and they are (1) 2D representation of a complex 3D maxillofacial structure, (2) incorporation of cephalometric tracing errors during planning, (3) face-bow transfer and dental model mounting errors, and (4) model surgery errors, surgical splint fabrication-induced errors, and so on [9, 10].

Fig. 2.4  Schematic illustration of 2D-assisted SFOA planning

2.4  3D Virtual Surgical Planning and 3D Splint Fabrication

2.4

13

3D Virtual Surgical Planning and 3D Splint Fabrication

3D virtual surgical planning (see Fig.  2.5) has brought newer insights and better outcomes in the assessment of the maxillofacial complex surgery, especially offsetting the demerits of 2D modality of image acquisition and diagnosis. 3D imaging modalities such as CBCT has expanded the diagnostic envelope and has become an indispensable diagnostic aid as it has made possible to visualize intricate details of the craniofacial structures as accurately as possible and to also enable cranial base superimposition with a voxel-wise method. This has made it possible to analyse structures such as temporomandibular joint and the extent to which craniofacial structures respond during the post-surgical phase. The individual treatment plan and execution will be discussed in the subsequent relevant chapters.

Fig. 2.5  Summary of 3D-assisted SFOA treatment planning showing integration of CBCT images, photogrammetry images, and intraoral scanner images for the creation of virtual composite model. Virtual planning software is used for the planning of surgery, and digital surgical splints are created on the computer monitor. The digital splints are then transferred via stereolithography file format to a 3D printer for the splint printing. The printed splints are used in the operating room

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2  Diagnosis and Treatment Planning of Surgery-First Orthognathic Approach

2.5

Conclusion

Strategic planning with emphasis on careful considerations such as requirements and objectives of each case plays a critical role in the successful execution of a treatment plan. The essential and supplementary tools of both analogue and 3D-assisted planning and execution are discussed, and their importance is emphasized. Strategic planning will help you uncover your available options, set priorities for them, and define the methods to achieve them.—Robert J. McKain

References 1. Sugawara J, Nagasaka H, Yamada S, Yokota S, Takahashi T, Nanda R. The application of orthodontic miniplates to sendai surgery first. Semin Orthod. 2018;24(1):17–36. 2. Nagasaka H, Sugawara J, Kawamura H, Nanda R. “Surgery first” skeletal Class III correction using the Skeletal Anchorage System. J Clin Orthod. 2009;43:97. 3. Baek S-H, Ahn H-W, Kwon Y-H, Choi J-Y. Surgery-first approach in skeletal class III malocclusion treated with 2-jaw surgery: evaluation of surgical movement and postoperative orthodontic treatment. J Craniofac Surg. 2010;21:332–8. 4. Hernández-Alfaro F, Guijarro-Martínez R, Molina-Coral A, Badía-Escriche C. “Surgery first” in bimaxillary orthognathic surgery. J Oral Maxillofac Surg. 2011;69:e201–e7. 5. Hernández-Alfaro F, Guijarro-Martínez R, Peiró-Guijarro MA. Surgery first in orthognathic surgery: what have we learned? A comprehensive workflow based on 45 consecutive cases. J Oral Maxillofac Surg. 2014;72:376–90. 6. Kim J-Y, Jung H-D, Kim SY, Park H-S, Jung Y-S.  Postoperative stability for surgery-first approach using intraoral vertical ramus osteotomy: 12 month follow-up. Br J Oral Maxillofac Surg. 2014;52:539–44. 7. Liou EJ, Chen P-H, Wang Y-C, Yu C-C, Huang C, Chen Y-R. Surgery-first accelerated orthognathic surgery: orthodontic guidelines and setup for model surgery. J Oral Maxillofac Surg. 2011;69:771–80. 8. Yu C-C, Chen P-H, Liou E, Huang C-S, Chen Y-R.  A surgery-first approach in surgical-­ orthodontic treatment of mandibular prognathism—a case report. Chang Gung Med J. 2010;33:699–705. 9. Lin H-H, Lo L-J. Three-dimensional computer-assisted surgical simulation and intraoperative navigation in orthognathic surgery: a literature review. J Formos Med Assoc. 2015;114:300–7. 10. Polley JW, Figueroa AA. Orthognathic positioning system: intraoperative system to transfer virtual surgical plan to operating field during orthognathic surgery. J Oral Maxillofac Surg. 2013;71:911–20.

3

Biological Principles and Responses to Surgery-First Orthognathic Approach

The skeleton is a record of past events and an oracle of future behaviors. —Webster S [1]

3.1

Introduction

Harold M.  Frost, an American orthopaedic surgeon, first described regional acceleratory phenomenon (RAP) as ‘a tissue reaction to different noxious stimuli’ [2]. Frost proposed the existence of RAP at a fracture site causes an acceleration of the normal repair and renewal process in both hard and soft tissue brings about healing within a period of time. This ubiquitous phenomenon plays a primary role in the healing process of all tissues. Further, in order to better define the remodelling process at the fracture site, Frost observed the existence of numerous remodelling sites and referred them as basic multicellular units (BMUs).

3.2

Regional Acceleratory Phenomenon

The BMUs respond to various biomechanical stimuli and are characterized by several distinctive phases, (a) activation phase, (b) resorption phase, (c) resting (or reversal) phase, and (d) formation phase, which represent the events involved in the bone healing process. The interaction of regional reparative reactions and the formation of granulation tissue result in the repair of the damage structure to the state of its original biomechanical integrity [3–5]. Since then, several independent researchers have placed a great deal of attention to evaluate the bone physiology on the basis of Frost’s RAP theory. This has given way to further our knowledge on the rate of remodelling in the region of bone fracture and also in understanding how tissue activity potentiates tissue healing under the influence of various local tissue © Springer Nature Switzerland AG 2019 C. K. Chng et al., Surgery-First Orthodontic Management, https://doi.org/10.1007/978-3-030-18696-8_3

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Skeletal Health

Spontaneous fractures Ruptures Arthoses Neoplasm

Optimal

Function Maintenance Repairs Microdamage

Disorder Induced

Sub-Optimal

Optimal Sub-Optimal Systemic Acceleratory Phenomenon (SAP)

Effector Cells • Osteoblasts • Osteoclasts

Regional Acceleratory Phenomenon (RAP)

Amino acids, Cytokines, Lipids, Local pH Tissue-level Mechanisms • Growth modelling • Remodelling • Maintenance Corticotomy/Osteotomy Piezoincision Micro-osteoperforations

Temperature, Laser, Electric Currents, and Magnetic Fields and Laser

Loads, Strains

Mechanical/Physical

Skeletal Physiology Agents

Non-Mechanical/NonPhysical

Genes, Race, Age, Sex

3  Biological Principles and Responses to Surgery-First Orthognathic Approach Calcium, Vitamin D3, Parathyroid, Hormone, Bisphosphonates, Corticosteroids, Osteocalcin

16

Fig. 3.1  Different physiological agents (mechanical and nonmechanical) can invoke tissue-level mechanisms that effect osteoblast and osteoclast cells. Re-establishment of a bone injury not only leads to a RAP but also to a systemic acceleratory phenomenon (SAP). Optimal and suboptimal levels of RAP and SAP induce different sets of reactions (skeletal health and disorder)

defence reactions. The study of growth and repair, and remodelling processes, subsequently leads to an establishment of a ‘new paradigm’ for bone biology [1, 6]. RAP can be invoked by any noxious stimuli as enumerated in Figs.  3.1 and 3.2. Once initiated, the BMU triggers a biological response, directly proportional to the

Substance P, CGRP, Histamine, Bradykinin, IL-1 α,4

Circumferential vascular disturbance, increased tissue pressure, increased GCF activity

IL-1R1 TNFR1,R2 TLR1-9 PG, NGF, SP, HIF-1α

Pain, Axonal degeneration Schwan cell activation Rapid Wallerian degeneration Neurotrophic factors release, catecholamine release

VEGF, C3a,b; C5a,b PG-D,E,F LT-B4,C4,D4,E4 Mac-1,NO

Bleeding, Inflammation, chemotaxis, Perfusion, Proliferation, Angiogenesis, Neovascularisation, fibrosis, cell turnover

IL-1 a,OPG,PDGF TNF, ICTP, OSM IFN, bALP, BMP, DKK PGE2, RANKL, Cbfa1/Runx2

Resorption, formation, osteoblast maturation, BMU, mIcrodamage repair

Teeth (Pulp) and periodontal ligament Soft tissue Bone

17

Plasma derived Complement activation C3a,b,5a,b Kinin System Fibrinolysis system Clotting system

RAP

Nervous system

Cell derived Vasoactive amines Arachidonic acid metabolites Lysosomal component Platelet activating factors (PAF) Cytokines Reactive Oxygen Species (ROS) nitrogen oxide (NO) Neuropeptide

Non-infection inflammatory process Fractures

Injury

Infection

Chemical Mediators

Surgery intervention

3.2  Regional Acceleratory Phenomenon

Fig. 3.2  RAP is a ubiquitous phenomenon that not just solely occurs in the skeletal system but also in the soft tissue, nervous system, and dental and periodontal ligament too, which is mediated by various plasma- and cell-derived mediators. Several mediators have been identified that play a direct or indirect role in the local and systemic acceleration of healing process. IL interleukin, OPG osteoprotegerin, PDGF platelet-derived growth factor, TNF tumour necrosis factor, ICTP C-terminal telopeptide of type I collagen, OSM oncostatin M, INF interferon, bALP bone alkaline phosphatase, BMP bone morphogenetic proteins, DKK Dickkopf homologue, PG prostaglandin, RANKL receptor activator of nuclear factor kappa-Β ligand, RUNX runt-related transcription factor, Cbf core binding factor, VEGF vascular endothelial growth factor, LT leukotriene, Mac macrophage-­1, NO nitrogen oxide, IL interleukin, TNF tumour necrosis factor, TLR toll-like receptors, NGF nerve growth factor, HIF hypoxia-inducible factor, SP specificity protein, CGRP calcitonin gene-related peptide

3  Biological Principles and Responses to Surgery-First Orthognathic Approach

18

magnitude and nature of stimulus [3], which leads to the cascade of the cyclical sequence of events of activation, resorption, and formation, commonly abbreviated as ‘ARF sequence’.

3.2.1 Systemic Acceleratory Phenomenon (SAP) Mueller, Schilling, and team at the University of Heidelberg, Germany, conducted a series of experiments to show that restoration of a local defect in a rat model not only leads to a regional acceleratory phenomenon (RAP) but also to a systemic acceleratory phenomenon (SAP) at distant sites of the skeleton [6–8]. SAP leads to the release of osteogenic growth peptide (OGP) which stimulates proliferation of alkaline phosphatase activity that ultimately accelerates bone repair process.

3.3

 steotomy- and Corticotomy-Assisted Tooth Movement O (Table 3.1)

Newer insights have unveiled the manner of tissue responses in corticotomy- and osteotomy-assisted tooth movements. Dentoalveolar procedures (periodontal flap surgery, exposure of palatally impacted canines, dental extractions), orthognathic jaw surgery osteotomy, corticotomy, and distraction osteogenesis are capable of altering the bone biology (increased activation of BMU).This subsequently Table 3.1  The table illustrating key features of osteotomy and corticotomy procedures Definition

Rate of tooth movement Immunostaining assessment MicroCT assessment Overall treatment time Periodontal problems (probing depth, recession, attachment loss, or bleeding on probing) Root resorption

Osteotomy Cutting through the cortical and trabecular bone to create a completely separate alveolar segment [21] Peaks at 1–3 weeks after surgically induced trauma. Phenomenon lasts for 3–4 months postoperatively [23] Less osteopenia around dental roots in comparison to corticotomy [15]

Corticotomy Only cortical bone is cut to improve bony remodelling [22]

No root resorption after surgically facilitated movement of teeth [22, 30]

No root resorption [22, 30]

Peaks at 3-week post-­ corticotomy. It lasts for 4 months postoperatively [24] More demineralization (porosity) observed around dental roots [15] Regional accelerated Distraction osteogenesis in the osteotomy-assisted tooth movement phenomenon was observed in the alveolar bone [12] is observed [12] Up to 50%. Reduction [9, 21, 25, 26] Reduction of 28% and 70% [9, 21, 25, 26] Non-detrimental effects [27–29] Non-detrimental effects [27–29]

3.4  Surgery-First Orthognathic Approach’s Molecular Response

19

significantly influences tooth movement [9–13]. Corticotomy is thought to induce a regional acceleratory phenomenon (RAP) that amplifies ‘ARF sequence’ in osteopenic bone [11, 14]. Longitudinal studies using computerized tomograms have shown that osteotomy and alveolar corticotomy produce different bone responses. Wang et al. histologically assessed in rats how dentoalveolar surgery alters the biology of tooth movement and showed that corticotomy site induced RAP with increased bone demineralization around the dental root allowing for movement through the demineralized bone prior to remineralization, whereas distraction osteogenesis occurs at the osteotomized segment [15]. Nonetheless, both processes form an integral part of bone repair [16]. Teng and Liou showed, in beagle dogs, that interdental osteotomies induce RAP and significantly accelerate orthodontic tooth movement by assessing rate of tooth movement, bone-specific biomarkers in gingival crevicular fluid, and bone demineralization by cone beam computed tomography scans (alveolar bone grey scale) [17].

3.4

 urgery-First Orthognathic Approach’s S Molecular Response

SFOA utilizes the sudden surge of cyclical sequence of bone modelling and remodelling events that ensues subsequent to osteotomy cuts made for the correction of jaw deformity. The osteotomy-assisted tooth movement is thought to accelerate significantly orthodontic tooth movement. It also reduces the total orthodontic treatment duration by using the RAP period to facilitate the orthodontic treatment phase. Recently, literature pertaining to relationship between corticotomy- and osteotomy-­ assisted tooth movement suggests alveolar bone surrounding teeth experiences short-term osteopenia or demineralization, especially at the corticotomy site. Buschang and colleagues observe that corticotomies hasten tooth movements because the ‘surgical insult’ produces RAP, and greater the injury, the more the tooth movement. Also, they observed that RAP reduces the amount and density of bone that the tooth has to traverse through. Hence, they concluded that ‘corticotomies should be considered as stable, undisplaced fractures that injures the periosteum and bone’ [18, 19]. Liou et  al. studied the postoperative changes in bone physiology and the corresponding responses in the dentoalveolus in orthognathic surgery subjects. The clinical study evaluated serum alkaline phosphatase (ALP) and C-terminal telopeptide of type I collagen (ICTP) bone markers and correlated with tooth mobility of maxillary and mandibular incisors using the Periotest method. The study concluded that jaw osteotomy triggered a 3- to 4-month period of increased osteoclastic activity and metabolic changes in the dentoalveolus postoperatively and corresponding increase in tooth mobility in the evaluated teeth. This study showed that temporary surge in ICTP (osteoclastic activity) and ALP (osteoblastic activity) indicated a transient burst of bone activation, resorption, and formation. This study also confirms the previous animal study that restoration of a local defect in a rat

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3  Biological Principles and Responses to Surgery-First Orthognathic Approach

model not only leads to a regional acceleratory phenomenon (RAP) but also to a systemic acceleratory phenomenon (SAP) at distant sites of the skeleton. Zingler et  al. in their prospective cohort study evaluated biological changes using GCF markers. The GCF markers, such as IL-1 b, IL-6, TGF b 1-3, MMP-2, and VEGF, were studied before and after SFOA, and Zingler et al. concluded that bone remodelling factors levels are elevated, which is reminiscent to fracture healing [20].

3.5

Conclusion

RAP is a complex physiologic phenomenon that researchers have only begun to understand. Further effort needs to be carried out in order to better understand the phenomenon. Several areas of RAP need further attention so that its clinical implications can be fully understood. Some areas of potential research would be: • Investigation of how chemical mediators (complement, vasoactive amines, neuropeptide, cytokines, vascular endothelial growth factor, etc.) are influenced by various noxious stimuli. • Further evaluation of molecular mechanisms underlying accelerated orthodontic tooth movement and effects on bone, soft tissues, nervous system, and periodontium. • In-depth analysis of RAP side-effects and risks associated with correlation of bone strength, fragility, and long-term characteristic evaluation of skeletal maturation. • Estimation of targeted changes in expression of specific genes.

References 1. Webster S. The past, present, and future of bone morphometry: its contribution to an improved understanding of bone biology. J Bone Miner Metab. 2005;23:1–10. 2. Frost H. The regional acceleratory phenomenon: a review. Henry Ford. Hosp Med J. 1983;31:3. 3. Verna C.  Regional acceleratory phenomenon. Tooth movement, vol. 18. Basel: Karger Publishers; 2016. p. 28–35. 4. Frost HM. Tetracycline-based histological analysis of bone remodeling. New York: Springer; 1969. 5. Frost HM.  Defining osteopenias and osteoporoses: another view (with insights from a new paradigm). Bone. 1997;20:385–91. 6. Mueller M, Schilling T, Minne HW, Ziegler R. A systemic acceleratory phenomenon (SAP) accompanies the regional acceleratory phenomenon (RAP) during healing of a bone defect in the rat. J Bone Miner Res. 1991;6:401–10. 7. Mueller M, Schilling T, Minne HW, Ziegler R. Does immobilization influence the systemic acceleratory phenomenon that accompanies local bone repair? J Bone Miner Res. 1992;7. 8. Schilling T, Mueller M, Minne HW, Ziegler R. Mineral apposition rate in rat cortical bone: physiologic differences in different sites of the same tibia. J Bone Miner Res. 1992;7. 9. Fischer T. Orthodontic treatment acceleration with corticotomy-assisted exposure of palatally impacted canines: a preliminary study. Angle Orthod. 2007;77:417–20.

References

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10. Liou EJ, Huang CS. Rapid canine retraction through distraction of the periodontal ligament. Am J Orthod Dentofacial Orthop. 1998;114:372–82. 11. Yaffe A, Fine N, Binderman I. Regional accelerated phenomenon in the mandible following mucoperiosteal flap surgery. J Periodontol. 1994;65:79–83. 12. Lee W, Karapetyan G, Moats R, Yamashita D-D, Moon H-B, Ferguson D, et al. Corticotomy-/ osteotomy-assisted tooth movement microCTs differ. J Dent Res. 2008;87:861–7. 13. Wilcko WM, Wilcko MT, Bouquot J, Ferguson DJ. Rapid orthodontics with alveolar reshaping: two case reports of decrowding. Int J Periodontics Restorative Dent. 2001;21:9–20. 14. Bogoch E, Gschwend N, Rahn B, Moran E, Perren S. Healing of cancellous bone osteotomy in rabbits—part I: regulation of bone volume and the regional acceleratory phenomenon in normal bone. J Orthop Res. 1993;11:285–91. 15. Wang L, Lee W, D-l L, Y-p L, Yamashita D-D, Yen SL-K. Tisssue responses in corticotomy-­ and osteotomy-assisted tooth movements in rats: histology and immunostaining. Am J Orthod Dentofacial Orthop. 2009;136(770):e1–e11. 16. Yen SL. A comparison between osteotomy and corticotomy-assisted tooth movement. Tooth movement, vol. 18. Basel: Karger Publishers; 2016. p. 124–9. 17. Teng GY, Liou EJ.  Interdental osteotomies induce regional acceleratory phenomenon and accelerate orthodontic tooth movement. J Oral Maxillofac Surg. 2014;72:19–29. 18. Buschang P, Campbell P, Ruso S.  Accelerating tooth movement with corticotomies: is it possible and desirable? Semin Orthod. 2012;18:286–94. 19. dos Santos-Pinto A, Araújo E, Ribeiro GLU, et  al. An interview with Peter H.  Buschang. Dental Press J Orthod. 2014;19:23–36. 20. Zingler S, Hakim E, Finke D, Brunner M, Saure D, Hoffmann J, et al. Surgery-first approach in orthognathic surgery: psychological and biological aspects—a prospective cohort study. J Craniomaxillofac Surg. 2017;45:1293–301. 21. İşeri H, Kişnişci R, Bzizi N, Tüz H. Rapid canine retraction and orthodontic treatment with dentoalveolar distraction osteogenesis. Am J Orthod Dentofacial Orthop. 2005;127:533–41. 22. Liem A, Hoogeveen E, Jansma J, Ren Y.  Surgically facilitated experimental movement of teeth: systematic review. Br J Oral Maxillofac Surg. 2015;53:491–506. 23. Liou EJ, Chen P-H, Wang Y-C, Yu C-C, Huang C, Chen Y-R.  Surgery-first accelerated orthognathic surgery: postoperative rapid orthodontic tooth movement. J Oral Maxillofac Surg. 2011;69:781–5. 24. Patterson BM, Dalci O, Darendeliler MA, Papadopoulou AK. Corticotomies and orthodontic tooth movement: a systematic review. J Oral Maxillofac Surg. 2016;74:453–73. 25. Vercellotti T, Podesta A.  Orthodontic microsurgery: a new surgically guided technique for dental movement. Int J Periodontics Restorative Dent. 2007;27(4):325–31. 26. Kişnişci RŞ, İşeri H, Tüz HH, Altug AT.  Dentoalveolar distraction osteogenesis for rapid orthodontic canine retraction. J Oral Maxillofac Surg. 2002;60:389–94. 27. Shoreibah E, Ibrahim S, Attia M, Diab M. Clinical and radiographic evaluation of bone grafting in corticotomy-facilitated orthodontics in adults. J Int Acad Periodontol. 2012;14:105–13. 28. Gantes B, Rathbun E, Anholm M.  Effects on the periodontium following corticotomy-­ facilitated orthodontics. Case reports. J Periodontol. 1990;61:234–8. 29. Shoreibah E, Salama A, Attia M, Abu-Seida S. Corticotomy-facilitated orthodontics in adults using a further modified technique. J Int Acad Periodontol. 2012;14:97–104. 30. Iino S, Sakoda S, Ito G, Nishimori T, Ikeda T, Miyawaki S. Acceleration of orthodontic tooth movement by alveolar corticotomy in the dog. Am J Orthod Dentofacial Orthop. 2007;131:448. e1–8.

4

Biomechanical Principles of Surgery-First Orthognathic Approach

Phileas Fogg, having shut the door of his house at half-past eleven, and having put his right foot before his left five hundred and seventy-five times, and his left foot before his right five hundred and seventy-six times, reached the Reform Club. —Jules Verne, Around the World in Eighty Days

4.1

Introduction

SFOA evaluation and planning have to be precise and require a meticulous step-by-­ step approach from case assessment to planning and the final execution of the surgery. In order to take cognizance of the dentofacial structures and their posed complexities, orthodontists expend a plethora of 3D techniques and modalities, such as 3D facial morphometrics, 3D non-contact laser scan, 3D cone beam computed tomography (CBCT), stereolithography, 3D ultrasound holography, finite element modelling, Moire topography, video imaging, and contour photography [1–5].

4.2

Six Degrees of Freedom (6DoF)

Among the above-mentioned imaging modalities, CBCT is the most widely used 3D radiography technique which facilitates the capture of important dentofacial structural details [6]. SFOA demands an in-depth understanding of dentofacial traits and various rotational and translational movements, in order to establish a surgical treatment objective (STO) [7]. The maxillo-mandibular complex (MMC) is like a rigid body with six degrees of freedom in three-dimensional space having three translation coordinate axes, namely, (1)sagittal, (2) transverse, and (3) vertical, and three rotation axes (1) pitch, (2) roll, and (3) yaw [6–8] (Fig. 4.1). © Springer Nature Switzerland AG 2019 C. K. Chng et al., Surgery-First Orthodontic Management, https://doi.org/10.1007/978-3-030-18696-8_4

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4  Biomechanical Principles of Surgery-First Orthognathic Approach

Fig. 4.1  Figure (left and right) illustrating a rigid body’s movement in a three-dimensional space with six degrees of freedom (translation—transverse, sagittal, and vertical) (rotation—pitch, roll, and yaw)

4.2.1 Natural Head Position: 2D and 3D Natural head position is the position of the head when the subject looks at a distant point at eye level and their visual axis is parallel to the ground [9]. Xia et al. describe a ‘global coordinate system’ comprising of local (maxilla, mandible, etc.) and global (whole head) reference frames that form an essential system to determine the facial configurations in both two and three dimensions [10]. In the past, several methods have been attempted to reproduce NHP consistently as Cassi et al. noted that NHP plays an important role when investigating the association between craniocervical posture and dentofacial morphology. It also forms a postural basis for assessment of craniofacial morphology [11]. Once the image is captured in NHP, further, NHP proof images can be used to plan surgery in the six degrees of freedom (6DoF). 6DoF refers to the freedom of movement of a rigid body in three-­ dimensional space. Specifically, the body is free to alter spatial position as forward/ backward (longitudinal or sagittal), up/down (vertical), and left/right (transverse) translation in three perpendicular axes. This is in combination with variations in orientation through rotation about three perpendicular axes, termed as yaw (vertical axis), pitch (transverse axis), and roll (longitudinal or sagittal or anteroposterior axis) [8, 10] (Fig. 4.1).

4.2.1.1 Pitch Pitch is defined as the body’s rotation fixed between the side-to-side axis (on a patient’s right ear to left ear or left to right lip corners) also known as the lateral or transverse axis. Pitch is referred as positive when the anterior segment is raised upward and posterior segment is lowered (Fig. 4.1).

4.3  Considerations of Translational (Sagittal, Transverse, Vertical) and Rotational…

25

4.2.1.2 Roll Roll is defined as the body’s rotation fixed between the front-to-back axis (on a patient’s lip to back of head or ANS to PNS) also known as the longitudinal axis. Roll is referred as positive when the left side is raised upward and the right segment is lowered (Fig. 4.1). 4.2.1.3 Yaw aw is defined as the body’s rotation fixed around the vertical axis (on a patient’s superior border of calvaria to mandible base). Yaw is referred as positive when the anterior segment moves to the right (Fig. 4.1).

4.3

 onsiderations of Translational (Sagittal, Transverse, C Vertical) and Rotational Envelopes (Pitch, Roll, and Yaw)

Traditional analogue techniques such as 2D radiography (lateral and postero-­ anterior cephalographs), facial photographs, and dental casts could be used to plan jaw surgery. Typically, translational and rotational movements of MMC are ascertained by amalgamation of radiographs (lateral and PA cephalographs) and gnathic profile field. The rule of thirds, along with pre-surgical measurements chart, is used for the initial assessment of SFOA cases (see Chap. 2, Fig. 2.3). Three horizontal planes and one vertical plane are drawn on the PA cephalograph and two horizontal reference planes on the lateral cephalograph (Fig. 4.2). Horizontal planes’ (PA cephalograph) topmost plane (cranial reference plane) runs from the left greater wing superior orbit—intersection of superior border of greater wing of sphenoid bone and lateral orbital margin, right and left. The middle plane (orbital plane) runs from midpoint of inferior orbital margin, right and left. The bottom plane (maxillary canine plane) runs from maxillary canine—tip of maxillary canine, right and left [12]. The vertical plane (midsagittal plane) is a plane running from crista galli (uppermost point on crista galli) to the line connecting cranial horizontal plane or orbital plane. In SFOA planning, the maxillary canine plane is subjective and may not be reliable as the teeth are not aligned, hence making maxillary canine plane difficult to use; however, the authors suggest to ascertain the true extent of maxillary teeth deviation by clinical evaluation (please refer to Chap. 2, Fig. 2.3). Horizontal planes’ (lateral cephalograph) top line, Frankfort horizontal plane, runs from the midpoint of the upper contour of the external auditory canal (anatomic porion) or a point midway between the top of the image of the left and right ear rods of the cephalostat (machine porion) to a point midway between the lowest point on the inferior margin of the two orbits (orbitale). The bottom plane (maxillary plane) runs from the anterior nasal spine (ANS), the most anterior point on the maxilla at the nasal base, to the posterior nasal spine (PNS), the tip of the posterior nasal spine of the palatine bone, at the junction of the soft and hard palate. The maxillary template with maxillary plane (ANS-PNS) is one of the key elements for planning six degrees of freedom movements. Although infinite movements are possible whilst correcting the maxillo-mandibular complex (MMC), however, the authors recommend application of some important ‘pivotal points’ to correct the

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4  Biomechanical Principles of Surgery-First Orthognathic Approach

Fig. 4.2  Figure depicting PA and lateral cephalograph tracings with reference planes and maxilla and mandible templates for the depiction of paper surgery in the form of six degrees of freedom

translational and rotational movements of maxilla. Image (top extreme left) (Fig. 4.3) shows ‘maxilla template’ with ‘five pivotal points’, which are located (1) distal to PNS, (2) at PNS, (3) in between ANS-PNS, (4) at ANS, and (5) mesial to ANS and are applied for maxilla pitch evaluation and correction. These aforementioned pivotal points are intended for the pitch correction and could be used in conjunction with correction of translation deficiency. The yaw correction can be visualized in the maxillary mounted cast and can be corrected accordingly (top extreme left) (Fig. 4.3). Figure 4.4a, b is a case illustrating the application of traditional orthodontic assessment tools in the planning of SFOA case with six degrees of freedom. The presurgery cephalometric evaluation depicted the following aberrations: (1) maxilla, hypoplastic (backward translation), anticlockwise tipping (positive pitching motion with ANS raised and PNS lowered) with downward translation at the right canine, and (2) mandible, hyperplastic (forward translation) and lateral translation (left side). Surgical planning is done by placing maxilla template on the original tracing; the maxilla is impacted for 3 mm at PNS and downward for 3 mm at ANS (clockwise

4.3  Considerations of Translational (Sagittal, Transverse, Vertical) and Rotational…

27

Fig. 4.3  Various movements of maxilla as ascertained by 6DoF

rotation, negative pitch) and advanced for 5 mm (forward translation). The mandible is translated (transverse movement) to the right side. The vertical excess is corrected by genioplasty (both sagittal and vertical translation correction). The amount of rotation and translation movements would be confirmed during the model surgery, and the surgical splints are created (Fig. 4.5). The maxilla was moved according to the paper surgery planning and fixed to create the intermediate splint by keeping mandible in its original position. Once the intermediate splint was created, the mandible was moved as planned. Subsequently, the final surgical splint is created. The drawbacks of traditional analogue techniques would include (1) 2D representation of a complex 3D maxillofacial structure, (2) incorporation of cephalometric tracing errors during planning, (3) face-bow transfer and dental model mounting errors, and (4) model surgery errors and surgical splint acrylization errors [13]. If the aforesaid shortcomings are controlled, then ‘paper and model surgery’ is beneficial

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4  Biomechanical Principles of Surgery-First Orthognathic Approach

as it allows the clinician to utilize the routine tools of assessment without depending on supplementary 3D imaging modalities.

4.3.1 Virtual Surgical Planning Advancements in computed tomography (CT) imaging and CAD/CAM (computer-­ aided design and computer-aided manufacturing) have made the adoption of this technology a lot easier and also the cost of adoption down in recent years. The planning of orthographic surgery using 3D technology is fast becoming the preferred choice of orthodontists and surgeons. Once the CT image is oriented to NHP, SFOA planning is primarily dependent on evaluating and setting the maxillary position. Once the maxilla is positioned, taking into account 6DoF, the mandible is essentially positioned based on the maxillary position whilst taking care of final

Fig. 4.4 (a) Maxilla and mandible template and MMC movements in vertical and sagittal directions using lateral cephalograph. (b) Maxilla and mandible template and MMC movements in vertical and transverse directions using postero-anterior cephalograph

4.3  Considerations of Translational (Sagittal, Transverse, Vertical) and Rotational…

29

Fig. 4.4  (continued)

Fig. 4.5  The planned paper surgery is simulated in the face-bow transfer articulator-mounted models. The maxilla is advanced and moved downward at ANS, along with impaction at PNS (red and yellow arrows). The mandible is set back to 6 mm. Enough clearance is provided (small red arrows) between the surgical splint and brackets to avoid accidental dislodgement during surgery

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4  Biomechanical Principles of Surgery-First Orthognathic Approach

Fig. 4.6  Pre-treatment images showing Class III facial profile with mandibular asymmetry

occlusion position. A three-point occlusal contact (two points of contact in the bilateral posterior segment and one in the anterior segment) is ideal. Otherwise, effort has to be made to produce at least two-point occlusal contacts bilaterally in the posterior segment. A case (Figs. 4.6, 4.7, 4.8, 4.9, and 4.10) is described in order to understand the pre-surgery complexities as determined with the aid of 3D imaging and the computer-assisted surgery planning using SFOA. A 3D pre-surgical evaluation showed a Class III malocclusion with maxillary hypoplasia, maxillary cant, and mandibular prognathism with both maxilla and mandible deviated to the left side. The treatment objective was to correct the hypoplastic maxilla and prognathic mandible, correct the left-sided shift, correct the maxillary cant, and establish positive overbite. The 3D evaluation showed maxillary cant with increased maxillary distance to FHP on the right side in comparison to left side. It is very important to identify whether the maxillary canting is due to dental issue or a skeletal issue or a combination of both. This discernment plays a vital role in the SFOA, as the teeth will not be aligned prior to surgery, and this would compromise the treatment planning if not evaluated appropriately [14, 15]. There are several ways of assessing the cant, and these are (1) clinical assessment (refer to Chap. 2), (2) frontal cephalographs, and (3) 3D morphometric assessment—surface-based and volume-based computed shape measurements and (4) mirroring method [16–19] (Figs. 4.11 and 4.12).

4.3  Considerations of Translational (Sagittal, Transverse, Vertical) and Rotational…

a

b

e

f

c

g

31

d

h

Fig. 4.7  Images showing both maxillary and mandibular facial asymmetry and 3D computer-­ assisted planning. (a, b) Showing the pre-treatment skeletal discrepancy. (c–f) Image showing the surgical planning by application of 6DoF movements; the maxillary skeletal movements are planned with reference to FHP, and subsequently the mandible follows the maxilla’s planned position whilst making sure that at least two-point occlusal contact is achieved. (g, h) In this case, a three-point contact is established with two points in the posterior region bilaterally at second molars and one point in the anterior region at incisal area

Fig. 4.8  Top images showing pre-treatment (left), predicted (middle), and post-surgery (right) profile view. Bottom images showing intermediate (left) and final (right) surgical splints

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4  Biomechanical Principles of Surgery-First Orthognathic Approach

Fig. 4.9  Immediate post-surgery extra- and intra-oral images

Fig. 4.10  Photos showing in between treatment

The maxilla is planned for differential impaction (LeFort I osteotomy) in 6DoF movements as explained in Table 4.1.

4.3  Considerations of Translational (Sagittal, Transverse, Vertical) and Rotational…

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Fig. 4.11  Post-treatment intra- and extra-oral images

Fig. 4.12  Post-treatment lateral cephalograph and OPG Table 4.1  Table explaining the 6DoF movements in terms of rotational and translational movement of the maxillo-mandibular complex

Maxilla

Rotation Pitch • Negative pitch • Clockwise rotation

Translation Roll Yaw Transverse Negative roll Positive Right side movement at left canine yaw and left molar

Mandible • Negative Negative roll Positive Right side movement at left canine yaw pitch • Clockwise and left molar rotation

Vertical • Downward movement at ANS • Impaction at PNS Downward movement at pogonion

Sagittal Advancement at ANS

Set-back at pogonion

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4.4

4  Biomechanical Principles of Surgery-First Orthognathic Approach

Conclusion

The importance of recording the NHP along with the proper evaluation of maxillo-­ mandibular complex in three dimensions with emphasis on 6DoF in both analogue and 3D-assisted planning is key in the success of SFOA. Meticulous planning and considerations of translational (sagittal, transverse, vertical) and rotational envelopes (pitch, roll, and yaw) have to be considered in relation to the dentition and soft tissue when planning for SFOA cases.

References 1. Ayoub A, Wray D, Moos K, Siebert P, Jin J, Niblett T, et al. Three-dimensional modeling for modern diagnosis and planning in maxillofacial surgery. Int J Adult Orthodon Orthognath Surg. 1996;11:225–33. 2. Hajeer MY, Ayoub AF, Millett DT, Bock M, Siebert J. Three-dimensional imaging in orthognathic surgery: the clinical application of a new method. Int J Adult Orthodon Orthognath Surg. 2002;17:318–30. 3. Kau C, Zhurov A, Bibb R, Hunter L, Richmond S. The investigation of the changing facial appearance of identical twins employing a three-dimensional laser imaging system. Orthod Craniofac Res. 2005;8:85–90. 4. Khambay B, Nebel J-C, Bowman J, Ayoub A, Walker F, Hadley D. A pilot study: 3D stereo photogrammetric image superimposition on to 3D CT scan images—the future of orthognathic surgery. Int J Adult Orthodon Orthognath Surg. 2002;17:331–41. 5. Plooij JM, Maal TJ, Haers P, Borstlap WA, Kuijpers-Jagtman AM, Bergé SJ. Digital three-­ dimensional image fusion processes for planning and evaluating orthodontics and orthognathic surgery. A systematic review. Int J Oral Maxillofac Surg. 2011;40:341–52. 6. Ryu H-S, An K-Y, Kang K-H. Cone-beam computed tomography based evaluation of rotational patterns of dentofacial structures in skeletal Class III deformity with mandibular asymmetry. Korean J Orthod. 2015;45:153–63. 7. Kim S-J, Lee K-J, Yu H-S, Jung Y-S, Baik H-S.  Three-dimensional effect of pitch, roll, and yaw rotations on maxillomandibular complex movement. J Cranio-Maxillofac Surg. 2015;43:264–73. 8. Dorafshar AH, Brazio PS, Mundinger GS, Mohan R, Brown EN, Rodriguez ED.  Found in space: computer-assisted orthognathic alignment of a total face allograft in six degrees of freedom. J Oral Maxillofac Surg. 2014;72:1788–800. 9. Marcotte MR. Head posture and dentofacial proportions. Angle Orthod. 1981;51:208–13. 10. Xia J, Gateno J, Teichgraeber J, Yuan P, Li J, Chen K-C, et al. Algorithm for planning a double-­ jaw orthognathic surgery using a computer-aided surgical simulation (CASS) protocol. Part 2: three-dimensional cephalometry. Int J Oral Maxillofac Surg. 2015;44:1441–50. 11. Cassi D, De Biase C, Tonni I, Gandolfini M, Di Blasio A, Piancino M. Natural position of the head: review of two-dimensional and three-dimensional methods of recording. Br J Oral Maxillofac Surg. 2016;54:233–40. 12. Trpkova B, Prasad NG, Lam EW, Raboud D, Glover KE, Major PW.  Assessment of facial asymmetries from posteroanterior cephalograms: validity of reference lines. Am J Orthod Dentofac Orthop. 2003;123:512–20. 13. Jeon J, Kim Y, Kim J, Kang H, Ji H, Son W.  New bimaxillary orthognathic surgery planning and model surgery based on the concept of six degrees of freedom. Korean J Orthod. 2013;43:42–52.

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14. Im J, Kang SH, Lee JY, Kim MK, Kim JH. Surgery-first approach using a three-dimensional virtual setup and surgical simulation for skeletal Class III correction. Korean J Orthod. 2014;44:330–41. 15. Liou EJ, Chen P-H, Wang Y-C, Yu C-C, Huang C, Chen Y-R. Surgery-first accelerated orthognathic surgery: orthodontic guidelines and setup for model surgery. J Oral Maxillofac Surg. 2011;69:771–80. 16. Alqattan M, Djordjevic J, Zhurov A, Richmond S. Comparison between landmark and surface-­ based three-dimensional analyses of facial asymmetry in adults. Eur J Orthod. 2013;37:1–12. 17. Berssenbrügge P, Berlin NF, Kebeck G, Runte C, Jung S, Kleinheinz J, et al. 2D and 3D analysis methods of facial asymmetry in comparison. J Cranio-Maxillofac Surg. 2014;42:e327–e34. 18. Huang C, Liu X, Chen Y. Facial asymmetry index in normal young adults. Orthod Craniofac Res. 2013;16:97–104. 19. Cevidanes LH, Tucker S, Styner M, Kim H, Chapuis J, Reyes M, et  al. Three-dimensional surgical simulation. Am J Orthod Dentofac Orthop. 2010;138:361–71.

5

Surgery-First Orthognathic Approach Treatment Protocol: Orthodontic Considerations

The secret of getting ahead is getting started. The secret of getting started is breaking your complex, overwhelming tasks into small manageable tasks, and then starting on the first one. —Mark Twain

5.1

Introduction

Orthodontic management involving bracket selection, arch wire sequencing, surgical splint duration, and elastic use plays an important role in the success of surgery-­first orthognathic approach cases. Considerations during pre-, post-surgery, and pre-surgical preparation phases must be taken into account to take full advantage of RAP for the conversion of transitional occlusion into final occlusion. The aim of this chapter is to describe the different treatment modalities adopted by various authors and also to enumerate our approach.

5.2

Pre-surgical Orthodontics

The pre-surgical orthodontics phase in SFOA involves a much shorter duration as opposed to conventional jaw surgery. In conventional jaw surgery, there is an emphasis on (1) arch coordination (dental expansion of the arches), (2) alleviation of crowding (levelling and alignment), and (3) dental decompensation in the form of up righting retroclined teeth and retraction of proclined teeth. This is done to ascertain the true skeletal deformity, [1] thus making it a time-consuming pre-­ surgical orthodontic stage. In SFOA, the pre-surgical orthodontic stage is reduced to minimal orthodontics where brackets are bonded but minimal or no orthodontic tooth movement is carried out. The orthodontic tooth movement is carried out post-surgery. © Springer Nature Switzerland AG 2019 C. K. Chng et al., Surgery-First Orthodontic Management, https://doi.org/10.1007/978-3-030-18696-8_5

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5  Surgery-First Orthognathic Approach Treatment Protocol: Orthodontic…

5.2.1 Orthodontic Appliances (Brackets and Arch Ligation) All SFOA practitioners (both orthodontist and surgeons) have their own individual technique and treatment philosophies that suit them as a team. No universal agreement exists on the choice of orthodontic appliances; however, the guiding principles of SFOA (i.e. minimal pre-surgical orthodontics) prevail. Table 5.1 illustrates different treatment protocols, and Table  5.2 illustrates our treatment protocol on orthodontic preparation. Several authors have reported placing fixed orthodontic bracket 1–6  weeks before the scheduled surgery date with the objective of placing passive arch wires or passively ligating the brackets with ligature wires [9, 11]. 1. Bracket slot size: The most commonly used bracket slot sizes are 0.018″ × 0.025″ (0.46 × 0.64 mm) and 0.022″ × 0.028″ (0.56 × 0.7 mm). 0.022″ × 0.028″ bracket slot allows the insertion of heavier arch wires making the levelling and aligning easier. 2. Ligation of brackets: Engaging passive rectangular stainless steel wires (0.017″  ×  0.025″) in a 0.022″  ×  0.028″ bracket slot could be done (Fig.  5.1); however, the placement of passive rectangular surgical wire is time-consuming and requires proficiency in making complex wire bends. Literature suggests bonding arch wire directly on to the teeth for the technical ease of speeding the pre-surgical procedure [3]. Post-surgically, this particular approach might pose difficulty in debonding the wire and bonding brackets in a fairly uncomfortable recovering patient [12]. The use of passive ligation of soft stainless steel ligature wires around the bracket and the advantages of applying stainless steel ligature wire are enumerated in the Table 5.2. A simple fix to this problem would be to place arch wires just prior to surgery (24 h). This will allow orthodontic tooth movement to start immediately post-surgery. 3. Surgical hooks: Kobayashi ligature hooks (K-hook) (0.012″ or 0.014″) (Fig. 5.2) ligated around the bracket require no use of heavy or rigid arch wire (rectangular arch wire), whereas the use of a crimpable surgical hook or a soldered hook requires a rigid arch wire, thus making Kobayashi hooks not only easy to use but often becomes the only option, especially in cases where the inter-bracket span is markedly reduced (e.g. severe crowding).

1 month before surgery brackets bonded 1 week before surgery

Liao et al. (2010) [4]

Villegas et al. (2010) [5]

NR

Baek et al. (2010) [3]

During SFOA Intermaxillary fixation duration and purpose IMF to prevent unwanted incisor extrusion

0.022″ slot

0.016″ × 0.016″ No, rigid fixation with NiTi additional 4 miniplates in the infrazygomatic crest and mandible

Used for achieving planned post-surgical occlusion

Surgical splints Optimal positioning and stabilization of the mandibular model Bonded directly Passive surgical No, only rigid Splint fixation removed to tooth surface wires, after 4 weeks dimension NR or ligated to brackets 0.022″ × 0.028″ 0.016″ × 0.022″ No, only rigid Splint removed NiTi, 1–3 days fixation with before surgery bone plates or immediately after surgery screws

SFOA treatment protocols: pre-, during-, and post-SFOA Pre-SFOA Preoperative Orthodontic appliance orthodontic Authors, publication preparation Brackets Wires time year Nagasaka NR 0.022″ slot 0.018″ × 0.025″ et al. passive SS (2009) [2]

Table 5.1  SFOA treatment protocols: pre-, during-, and post-SFOA

Orthodontic treatment commencement post-surgery 1 month

2 weeks Class III was overcorrected to Class II occlusion

4 weeks Creation of large overjet for lower incisor correction Molars are the Immediately after surgery guide to anteroposterior jaw positioning

Transitional occlusion Class III was overcorrected to Class II occlusion

Post-SFOA

Class III elastics to prevent relapse of the anterior crossbite Class II elastics for correction of incomplete incisor decompensation Elastomeric chain and NiTi coil springs used from miniplates

Type of elastics, duration, and purpose Vertical elastics to stabilize jaw position and masticatory function

(continued)

0.016″ × 0.016″ NiTi upper, 0.014″ NiTi lower, 0.016″ × 0.016″ SS after 2 weeks

0.016″ × 0.022″ Niti 0.016″ × 0.022″ SS

NR

Arch wire sequencing NiTi wires Sequencing NR

5.2  Pre-surgical Orthodontics 39

Aristizabal 1 week et al. (2015) [8]

Hernandez-­ 1 week before Alfaro surgery et al. (2014) [7]

Self-ligating

During SFOA Intermaxillary fixation duration and purpose IMF removed after surgery

Surgical splints Splint used for maxillary arch expansion, removed 6 weeks after surgery Used for Soft arch wires 0.12-mm achieving interdental 1 day before wire loops and planned surgery left in place for post-surgical occlusion 2 weeks No arch wire 0.014″ NiTi wires placed in the operation room

SFOA treatment protocols: pre-, during-, and post-SFOA Pre-SFOA Preoperative Orthodontic appliance orthodontic Authors, publication preparation Brackets Wires time year Uribe et al. 4 weeks 0.022″ slot 0.016″ × 0.016″ (2013) [6] NiTi

Table 5.1 (continued)

NR

Transitional occlusion Occlusion was planned based on corrective skeletal needs

Post-SFOA

2 weeks

Orthodontic treatment commencement post-surgery 2 weeks

Z elastics provided additional transversal control 3/16″, 3.5 Oz 1/4″, 3.5 Oz

Type of elastics, duration, and purpose Short Class II elastics

• 0.014″ • 0.014″ × 0.025″ Cu NiTi • 0.018″ × 0.025″Cu NiTi • 0.019″ × 0.025″ TMA

Change every 2–3 weeks

Arch wire sequencing Smaller dimension wires

40 5  Surgery-First Orthognathic Approach Treatment Protocol: Orthodontic…

NR

Brackets bonded

Passive SS ligature wire

NR

IMF removed after surgery

Used for simulating surgery

Used for simulating surgery and estimate the extent of post-surgical orthodontic treatment

NR ‘Surgical temporary occlusion’ was adapted into skeletal discrepancy and reorganized in the predicted location 2 weeks Intended transitional occlusion (ITM), molar relation used as a starting point to guide a temporary occlusion

NR not reported, IMF intermaxillary fixation, SFOA surgery first orthognathic approach, SS stainless steel

Brackets No HB Yu pre-surgical bonded et al. (2015) [10] orthodontics

Choi et al. (2015) [9]

NR

NR

NR

NR

5.2  Pre-surgical Orthodontics 41

During SFOA

Intermaxillary fixation duration and purpose Surgical splints

Used for achieving planned post-surgical occlusion • For single jaw surgery: only one splint is used • For double jaw surgery: two splints are used (intermediate and final) Use of splints is only during the time of surgery as a guide for the surgeon and removed post-surgery to commence tooth movement

0.022″ × 0.028″ slot Ligation with SS passive ligature wire, this approach has the following advantages: • No undue tooth movement before or during surgery as the wire is passive, unlike active arch wires • All brackets are secured with no possibility of dislodgment, even if the brackets dislodge, the passive ligature will not allow the bracket to release and accidental drop into open surgical sites • No additional use of rubber ligature tie, hence avoidance of oral hygiene deterioration due to rubber ties • Avoidance of complex wire bending in order to adapt to malocclusion • Saves chairside time IMF used only to stabilize the jaws during surgery such that rigid fixation with bone plates or screws is used to fix the osteotomy segments

Authors SFOA treatment protocols: pre-, during, and post-SFOA 1–2 weeks Pre-­ Preoperative SFOA orthodontic Preparation time Orthodontic appliance Brackets Wires

Table 5.2  Authors SFOA—treatment protocols: pre-, during, and post-SFOA

42 5  Surgery-First Orthognathic Approach Treatment Protocol: Orthodontic…

a

Ormco Corporation, Orange, CA, USA

Authors SFOA treatment protocols: pre-, during, and post-SFOA PostTransitional occlusion An occlusion is created such that orthodontically treatable malocclusion persists. (See chapter text for further SFOA understanding.) Orthodontic treatment 1–2 weeks commencement post-surgery Type of elastics, Wires Elasticsa Class II/Class III Midline correction Anterior box Posterior box duration, and purpose Fox Parrot Quail Fox 0.018″ 1/4″(3.5 Oz/100 g) 3/16″(2 Oz/60 g) 1/4″(3.5 Oz/100 g) 5/16″ Cu NiTi/0.016″ × 0.022″ NiTi Rabbit (2 Oz/60 g) Rabbit 3/16″ 3/16″ (3.5 Oz/100 g) (3.5 Oz/100 g) Moose Impala Zebra Moose 0.017″ × 0.025″ TMA low friction 5/16″ (6 Oz/170 g) 3/16″ (6 Oz/170 g) 5/16″(4.5 Oz/130 g) 5/16″ (6 Oz/170 g) •  Elastics: Full-time wear Arch wire sequencing 0.014 NiTi/0.018″ Cu NiTi One week post-surgery for minor/moderate crowding alleviation Upper and lower arch wires 0.016″ × 0.022″ NiTi Within ≤3 months post-surgery Upper and lower arch wires • With second-order bends and Class II/Class III elastics 0.017″ × 0.025″ TMA low friction • Cantilever mechanics Upper and lower arch wires For settling of occlusion and finishing and detailing 0.018″ SS/0.017″ × 0.025″ TMA low friction Upper and lower arch wires 0.21″ × 0.25″ TMA low friction/SS Upper and lower arch wires Adjunct appliances Chin cap can be applied to prevent the mandibular skeletal relapse in the first 3 months postoperatively

5.2  Pre-surgical Orthodontics 43

44

5  Surgery-First Orthognathic Approach Treatment Protocol: Orthodontic…

Fig. 5.1  Images showing complex wire bending in order to adapt to the unresolved pre-treatment tooth positions. This method of adapting heavy rectangular arch wires might provide enough stiffness in the form of placement of surgical hooks directly on the rigid arch wire for the application of surgical splint during surgery. However, it might be a time-consuming procedure that requires dexterous clinician, and if the wire is not handled well, there is a potential to incorporate undesirable torque in the wire. Typically, a (0.017 × 0.025″ or 0.018 × 0.025″ SS/TMA) rectangular wire is annealed to minimise the wires yield and tensile strength, and increase its ductlity so that the wire is soft enough for finger-pressure adaptaion and yet maintain rigidity to hold surgical hooks

Fig. 5.2  Image showing passive stainless steel ligature wires used to secure the brackets before surgery (right side) and K-hooks ligated to the brackets. Post-surgery, K-hooks are utilized to hook elastics

5.3

Pre-surgical Preparation

1 . Determination of transitional occlusion. 2. Surgical splint fabrication, intermaxillary fixation.

5.3.1 Determination of Transitional Occlusion Several authors have termed the planned occlusion that is determined during model surgery as the transitional occlusion (Figs. 5.3 and 5.4) [13], treatable malocclusion [14], surgical temporary occlusion [9], or intended transitional occlusion (ITM) [10]. The transitional occlusion is an occlusion that is set up immediately after surgery such that the existing malocclusion lies within the orthodontically manageable tooth movement boundary. Further, the ‘transitional occlusion’ could

5.3  Pre-surgical Preparation

45

Fig. 5.3  Images (top row) illustrating a skeletal Class III subject showing horizontal growth pattern with deep curve of Spee. Images (middle row) showing a transitional occlusion are created on articulator-mounted study models, wherein a three-point contact is established with two-point contact on the bilateral second molars and one-point contact in the anterior teeth such that buccal open bite is created. Subsequently, the buccal open bite is corrected postoperatively, thus correcting the deep curve of Spee. Images (bottom row) showing immediate post-surgery, where the exact planned transitional occlusion set-up is emulated in the surgery

Fig. 5.4  Images (top row) showing a skeletal Class III subject having moderate crowding, mild anterior open bite, and a vertical growth pattern. A 3D surgery planning software (middle row) is used to plan the transitional occlusion with a clockwise maxilla advancement and downward movement and anticlockwise mandibular setback such that vertical excess is resolved and also anterior open bite is corrected. Images (bottom row) showing final result immediately after surgery

be transfigured into a final occlusion to establish a stable relationship between the occlusion and corrected skeletal structures. There is an ideal anatomic relationship with opposing dentition exhibiting a cusp to fossa relationship which results in structural durability, functional efficiency, and aesthetic harmony.

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5  Surgery-First Orthognathic Approach Treatment Protocol: Orthodontic…

5.3.1.1 Prerequisites of a Transitional Occlusion In the conventional orthognathic surgery approach, pre-surgical orthodontic treatment is performed such that the dental component is decompensated to reveal the true skeletal discrepancy. The pre-surgical orthodontics ensures fabrication of a ‘surgical splint’ such that the maxilla and mandible are placed in a ‘concrete occlusion’ with minimal post-surgical orthodontic treatment. In SFOA, as teeth are malpositioned and lack proper occlusal antagonists in opposite arch, a ‘transitional occlusion’ has to be set up post-surgically. Some key elements are enumerated in this chapter (further details regarding case-by-case requisites of ‘transitional occlusion’ are explained in Chaps. 7–10) before setting up a ‘transitional occlusion’ during model surgery, and they are as follows: • Sagittal plane –– For minimal or moderate crowding cases, establishing positive overjet or an occlusion with three-point contact with two points contacting at the posterior teeth preferably at bilateral molars and one point at the anterior teeth such that a tripod effect is created [15]. The three-point contact with one point contacting the anterior teeth should be attempted only if the inclination of the anterior teeth is within normal limits. If the anteriors require correction (retroclined or proclined), then it’s prudent to avoid using the anterior teeth for a three-point contact and should resort to a two-point contact of bilateral posterior teeth. –– For severely retroclined or crowded lower anterior teeth and proclined upper anterior teeth cases, creation of larger positive overjet such that the large overjet can be utilized for lower incisors uprighting or decrowding and/or retraction of proclined upper incisors. A two-point contact of bilateral posterior teeth should be attempted in the aforementioned scenario, as referencing the anterior teeth will not be appropriate. Liao et al. recommended considering extraction if the upper incisor to occlusion plane angulation is less than 53–55° [4, 16]. • Transverse plane –– Intercanine and intermolar width of upper and lower dentition is maintained. –– Crossbite not more than one buccal cusp width of maxillary molar. • Vertical plane –– For hypodivergent skeletal pattern with deep curve of Spee: edge-to-edge anterior teeth with no occlusion in the posterior teeth such that posterior teeth can be extruded post-surgically (Fig. 5.4). –– For hyperdivergent skeletal pattern with anterior open bite: positive overjet with clockwise rotation of maxilla and anticlockwise rotation of mandible to counter post-surgical relapse of open bite (Fig. 5.5). Merits • Transitional occlusion model set-up permits evaluation of possibilities of surgery-­first orthognathic approach [9]. • Pre-surgical dental decompensation is avoided [13]. • Possible to ascertain post-surgical arch wire sequencing [9].

5.3  Pre-surgical Preparation

47

Fig. 5.5  A good fit of the surgical splints with enough clearance of the splint from the adjacent brackets (red arrows) will prevent the splint from rocking and also avert brackets from debonding by inadvertent force application during surgery

Demerits • Both the surgeon and orthodontist require experience to visualize the post-­ surgical transitional occlusion [13]. • Requires accurate prediction of the postoperative orthodontic treatment for dental alignment, incisor decompensation, arch coordination, and occlusal settling [9]. • The surgeon must be proficient at performing planned osteotomies with surgical splint on dental arches with existing malocclusion and achieve required post-­ surgical stability [14].

5.3.2 Surgical Splint Fabrication, Intermaxillary Fixation During the surgery, the orthodontist plays a key role, along with the surgeon, in the determination of the surgical splints as well as the intermaxillary fixation management. This section discusses the IMF and surgical splints indications, purpose, and duration. Different techniques to perform intermaxillary fixation (IMF), such as direct interdental wiring, IMF screws, arch bars, eyelet wiring, and cap splints, are available [2, 4, 7, 8, 10–15, 17, 18]. IMF serves as a mode of immobilizing the jaw segments [2, 7, 12]. The objectives of minimizing the duration of the IMF and surgical

48

5  Surgery-First Orthognathic Approach Treatment Protocol: Orthodontic…

splint immediately after jaw surgery, instead of keeping it for several weeks, are as follows: Firstly, commence orthodontic tooth movement as soon as possible such that regional acceleratory phenomenon can be utilized to the maximum. Secondly, the rigid internal fixation, if done adequately, is sturdy enough to resist relapse which is thought to occur due to premature occlusal interferences. Thirdly, if the IMF is left for several weeks post-surgery, one must consider additional days of hospitalization along with postoperative recovery issues such as assisted feeding and oral hygiene deterioration.

5.3.2.1 Surgical Splints Duration and Purpose The primary purpose of the surgical splints is to emulate the planned surgical movement (Fig. 5.5). Once the osteotomy cuts are made and the jaws are placed in the planned position, the final surgical splint is discontinued without any further use. Literature has indicated the use of the final surgical splint as a ‘post-surgical occlusal guide’ with the intention that the surgical splint will minimize the occlusal instability that may occur during the bone healing period. Also, if the surgical splint is used as a post-surgical guide, the splint requires frequent selective grinding to accommodate tooth movement [2, 3]. The surgical splint as a post-surgical occlusal guide may not be necessary because: 1 . Rigid fixations can overcome the instability that might follow. 2. Occlusal guide grinding demands precision and considerable chairside time. 3. Minimal mouth opening, during the postoperative recovery time, the patient will be under remarkable stress during the surgical splint manoeuvring.

5.4

Post-surgery in Surgery-First Orthognathic Approach

1 . Post-surgical orthodontic considerations. 2. Post-surgical orthopaedic management, i.e. chin cup therapy.

5.4.1 Post-surgical Orthodontic Considerations Post-surgical orthodontic treatment, type of elastic, duration, and arch wire sequencing are explained in further chapters and summarized in Table 5.2.

5.4.2 P  ost-surgical Orthopaedic Management, i.e. Chin Cup Therapy Post-surgery application of orthopaedic-force chin cup appliance in Class III patients provides a substantial support for the retention of Class III correction, thus

5.5 Conclusion

49

Fig. 5.6  Images showing application of high pull chin cup immediately after surgery in a skeletal Class III individual with excessive lower anterior face height

ensuring minimal or no skeletal relapse. It is important to apply the chin cup (Fig. 5.6) as early as possible, preferably, within the first week post-surgery whilst taking care of facial swelling that has occurred after surgery. The chin cup should be continued for the first 3–4 months post-surgery. Appropriate cushioning has to be provided for patient comfort. The wear duration, direction, and force magnitude play an important role when utilizing chin cup for the skeletal Class III correction retention. 1. Wear duration: Apply as soon as possible postoperatively with full-time application in the first month followed by nighttime (10–12 h) wear in the second and third months. 2. Force magnitude: Broadly based on chin cup direction. The chin cup can be divided into occipital-pull, intended for patients that had shown mandibular protrusion with horizontal growth pattern (low-angle case), and a vertical-pull (temporal pull), which could be used for steep mandibular plane angle and excessive anterior facial height with vertical growth pattern (high-angle case) (Fig.  5.6). Force magnitude, begin with lighter force of approximately 250  g (9 Oz) per side and gradually increase to 16 Oz (450 g).

5.5

Conclusion

Considerations must be given to appropriate choice of orthodontic appliances. The chapter describes the various options that are available and the reason for opting them. Also, considerations during the contemplation of transitional occlusion are described. Post-surgical orthodontic treatment strategies in terms of elastic usage, duration, and arch wire sequencing are elaborated in detail with the application of adjunct appliances such as chin cup. Acknowledgement  The authors would like to thank Prof. Akshai Shetty, Department of Orthodontics, RV Dental College, Bengaluru, Karnataka, India, for providing Fig. 5.1.

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References 1. Park JH, Papademetriou M, Kwon Y-D, editors. Orthodontic considerations in orthognathic surgery: Who does what, when, where and how? Seminars in Orthodontics. Amsterdam: Elsevier; 2016. 2. Nagasaka H, Sugawara J, Kawamura H, Nanda R. “Surgery first” skeletal Class III correction using the Skeletal Anchorage System. J Clin Orthod. 2009;43:97. 3. Baek S-H, Ahn H-W, Kwon Y-H, Choi J-Y.  Surgery-first approach in skeletal class III malocclusion treated with 2-jaw surgery: evaluation of surgical movement and postoperative orthodontic treatment. J Craniofac Surg. 2010;21:332–8. 4. Liao Y-F, Chiu Y-T, Huang C-S, Ko EW-C, Chen Y-R.  Presurgical orthodontics versus no presurgical orthodontics: treatment outcome of surgical-orthodontic correction for skeletal class III open bite. Plast Reconstr Surg. 2010;126:2074–83. 5. Villegas C, Uribe F, Sugawara J, Nanda R.  Expedited correction of significant dentofacial asymmetry using a “surgery first” approach. J Clin Orthod. 2010;44:97–103. 6. Uribe F, Janakiraman N, Shafer D, Nanda R.  Three-dimensional cone-beam computed tomography-­based virtual treatment planning and fabrication of a surgical splint for asymmetric patients: surgery first approach. Am J Orthod Dentofac Orthop. 2013;144:748–58. 7. Hernández-Alfaro F, Guijarro-Martínez R, Peiró-Guijarro MA. Surgery first in orthognathic surgery: what have we learned? A comprehensive workflow based on 45 consecutive cases. J Oral Maxillofac Surg. 2014;72:376–90. 8. Aristizábal JF, Martínez Smit R, Villegas C. The “surgery first” approach with passive self-­ ligating brackets for expedited treatment of skeletal Class III malocclusion. J Clin Orthod. 2015;49:361–70. 9. Choi JW, Lee JY, Yang SJ, Koh KS. The reliability of a surgery-first orthognathic approach without presurgical orthodontic treatment for skeletal class III dentofacial deformity. Ann Plast Surg. 2015;74:333–41. 10. Yu H, Mao L, Wang X, Fang B, Shen S. The surgery-first approach in orthognathic surgery: a retrospective study of 50 cases. Int J Oral Maxillofac Surg. 2015;44:1463–7. 11. Peiró-Guijarro MA, Guijarro-Martínez R, Hernández-Alfaro F. Surgery first in orthognathic surgery: a systematic review of the literature. Am J Orthod Dentofac Orthop. 2016;149:448–62. 12. Kim JH, Mahdavie NN, Evans CA.  Guidelines for “surgery first” orthodontic treatment. Orthodontics-basic aspects and clinical considerations. InTech. 2012. 13. Liou EJ, Chen P-H, Wang Y-C, Yu C-C, Huang C, Chen Y-R.  Surgery-first accelerated orthognathic surgery: postoperative rapid orthodontic tooth movement. J Oral Maxillofac Surg. 2011;69:781–5. 14. Huang C, Hsu S, Chen Y-R. Systematic review of the surgery-first approach in orthognathic surgery. Biom J. 2014;37:184. 15. Gandedkar NH, Chng CK, Tan W.  Surgery-first orthognathic approach case series: salient features and guidelines. J Orthod Sci. 2016;5:35. 16. Kim J-Y, Jung H-D, Kim SY, Park H-S, Jung Y-S.  Postoperative stability for surgery-first approach using intraoral vertical ramus osteotomy: 12 month follow-up. Br J Oral Maxillofac Surg. 2014;52:539–44. 17. Park H-M, Lee Y-K, Choi J-Y, Baek S-H. Maxillary incisor inclination of skeletal Class III patients treated with extraction of the upper first premolars and two-jaw surgery: conventional orthognathic surgery vs surgery-first approach. Angle Orthod. 2013;84:720–9. 18. Uribe F, Agarwal S, Shafer D, Nanda R.  Increasing orthodontic and orthognathic surgery treatment efficiency with a modified surgery-first approach. Am J Orthod Dentofac Orthop. 2015;148:838–48.

6

Surgical Management: Author’s Surgery-First Treatment Protocol

6.1

Introduction

Several developments and refinements, over the years, with regard to (1) surgery technique and approach, (2) fixation methods of osteotomy segment, and (3) general surgical management, have made corrections of dentofacial deformity, with jaw surgery an effective and predictable procedure with quality outcomes. Every surgeon has a preferred technique and style of operation, and the surgical technique per se, in SFOA, does not differ much in comparison to conventional surgery. Hence, the routine planning involving conventional jaw surgery should be followed for SFOA as well, along with additional considerations, and they are: 1. A thorough understanding of the postoperative occlusal/interarch relationship of maxillo-mandibular complex should be ascertained during the surgery planning phase with emphasis on ‘transitional occlusion’, as the surgery relies minimally on a stable occlusal relationship post-surgery. 2. While considering segmental osteotomies for the correction of skeletal jaw deformity, the following anatomical structures demand special attention: (a) Dentoalveolar structures. • Tooth root (dimension, number, anatomical variations—dilaceration) should be taken into account along with mechanical or iatrogenic damage to the tooth root and subsequent pulpal necrosis. • Periodontal ligament space (proximity to osteotomy cut) and alveolar bone (fenestration, dehiscence, bone quality). (b) Vascular supply (preservation of blood supply and haemorrhage). (c) Neurosensory involvement (hyperaesthesia). Pelo et al. conducted a systematic review to assess the risks in surgery-first orthognathic approach and, in particular, focusing on the complications of segmental osteotomies of the jaws. Their study concluded that the risks associated with SFOA segmental osteotomies are similar in nature as compared to conventional jaw surgery, © Springer Nature Switzerland AG 2019 C. K. Chng et al., Surgery-First Orthodontic Management, https://doi.org/10.1007/978-3-030-18696-8_6

51

52

6  Surgical Management: Author’s Surgery-First Treatment Protocol

but also concluded that due to lack of studies on SFOA-related osteotomy complications, the risk associated with SFOA appears higher than with conventional surgery. They also noted that the aforementioned observation could be due to a smaller number of SFOA studies which could lead to an exaggeration of the findings, and studies with larger sample sizes would be required to confirm the findings [1].

6.2

 ype of Surgery with Indications, Complications, T Considerations and Stability with the Type of Surgery

Table 6.1 describes the different types of surgery with indications, complications, considerations, and stability. Table 6.1  Table illustrating the type of surgery with indications, complications, considerations, and stability [2–6] Surgical technique LeFort osteotomy

BSSO sagittal split ramus osteotomy

Indications •  Plethora of maxillary spatial corrections involving one-piece or multipiece osteotomies •  Auto- and anticlockwise rotation of the maxilla • Mandibular advancement and setback •  Auto- and anticlockwise rotation of the mandible

Complications •  Posterior bony interferences preventing desired positioning and resultant posterior occlusal premature contacts • Improper condylar positioning during fixation leading to immediate relapse • Pterygomasseteric sling stripping • Intraoperative bleeding •  Inferior alveolar nerve damage •  Interferences of proximal and distal segments during large setbacks •  Torqueing of segments during fixation leading to ‘condylar sagging’

Considerations •  Complete posterior bone trimming •  Allow appropriate condylar seating •  Allow soft tissue releases to reduce soft tissue tension

Stability •  Bone grafts assist in the healing and long-term stability of LeFort osteotomies

•  Use of lag •  Cortical bone screw fixation thickness should be considered •  Extraction of impacted third molar prior to surgery •  Use of lag screw • Maxillo-mandibular training elastics until primary healing period (about 10 days post-surgery) •  The distal portion of proximal segment requiring trimming to avoid interferences •  Avoidance of torqueing of segments (continued)

6.2  Type of Surgery with Indications, Complications, Considerations and Stability...

53

Table 6.1 (continued) Surgical technique Inverted ‘L’ osteotomy

Vertical ramus osteotomy

Subapical osteotomies/ interdental osteotomies

Genioplasty

Indications • Mandibular advancement and ramus vertical lengthening •  Rotate or reposition the mandible posteriorly with asymmetry •  Amount of mandibular advancement and vertical lengthening possible •  Rotate or reposition the mandible posteriorly with asymmetry • Secondary correction of prior SSRO failures

Complications •  Dead space is created between the bony gaps while advancing the mandible • Temporalis muscle attachment acts as a hindrance for advancement

Considerations •  Bone grafting is required to fill the space created during advancement

Stability • Rigid fixation is recommended

•  Unseating of the condyle in the glenoid fossa • ‘Condylar sagging’ leading to immediate postoperative occlusal discrepancy

• Rigid fixation is recommended

• Segmental discrepancies in the occlusion •  Supra- or infra-eruption of teeth requiring dentoalveolar repositioning • Bimaxillary protrusion. •  Adjunct to en bloc or segmental osteotomies or in isolation to enhance the surgery outcome

•  Inferior alveolar nerve damage •  Mental branches damage •  Non-­vitality of the teeth

•  Coronoid processes might hinder large advancement as it interferes on the zygomatic arch •  Temporalis muscle stretch should be considered • Consider coronoidectomy if large advancement is required •  Consider minimal medial pterygoid stripping for proper seating of condyle in glenoid fossa •  Inferior alveolar nerve and mental foramen must be identified and preserved •  Teeth root position and avoid dehiscence and fenestration • Consider re-approximation of the mentalis muscles •  Horizontal cut should be at least 5 mm below the teeth apices •  The final outcome must be visualized either during the surgery planning phase or during the surgery •  Preservation of lingual blood supply

• Genioplasty segments stabilized with plates are more stable

•  Non-­vitality of the teeth •  Lack of blood supply •  Mental nerve damage •  Failure to achieve cosmetic objectives

•  Wearing of occlusal splint along with plates is recommended

54

6.3

6  Surgical Management: Author’s Surgery-First Treatment Protocol

Conclusion

Success of SFOA relies on a close working relationship between the surgeon and the orthodontist, from planning to execution to postoperative follow-up. Both the orthodontist and the surgeon should have profound understanding of each other’s capabilities and limitations of the specialities and to work on the strength of the other to ultimately accomplish a highly predictable, safe, and desirable patient outcome.

References 1. Pelo S, Saponaro G, Patini R, Staderini E, Giordano A, Gasparini G, et al. Risks in surgery-­ first orthognathic approach: complications of segmental osteotomies of the jaws. A systematic review. Eur Rev Med Pharmacol Sci. 2017;21(1):4–12. 2. Al-Moraissi EA, Ellis E. Is there a difference in stability or neurosensory function between bilateral sagittal split ramus osteotomy and intraoral vertical ramus osteotomy for mandibular setback? J Oral Maxillofac Surg. 2015;73(7):1360–71. 3. Mihalik CA, Proffit WR, Phillips C. Long-term follow-up of Class II adults treated with orthodontic camouflage: a comparison with orthognathic surgery outcomes. Am J Orthod Dentofac Orthop. 2003;123(3):266–78. 4. Proffit WR, Turvey TA, Phillips C. The hierarchy of stability and predictability in orthognathic surgery with rigid fixation: an update and extension. Head Face Med. 2007;3(1):21. 5. Wolford LM, Spiro CK, Mehra P. Considerations for orthognathic surgery during growth, part 1: mandibular deformities. Am J Orthod Dentofac Orthop. 2001;19:95–101. 6. Greenberg AM, Prein J. Craniomaxillofacial reconstructive and corrective bone surgery principles of internal fixation using the AO/ASIF technique. New York: Springer; 2002.

7

Management of Skeletal Class I Malocclusion with Surgery-First Orthognathic Approach

7.1

Introduction

Skeletal Class I patients requiring surgery predominantly exhibit a severe sagittal discrepancy, either in a bimaxillary protrusion or a retrusion relationship. Fig 7.1 describes the treatment guideline for the correction of such deformities. Control of maxillary occlusal plane is the key for the successful treatment of skeletal Class I malocclusion. This could be achieved either by en bloc distalization or mesialization of the maxilla by performing a LeFort I osteotomy and bilateral sagittal split osteotomy or by anterior segmental osteotomy.

7.2

 keletal Class I Malocclusion SFOA Treatment S Guidelines

The factors to be considered when performing these surgeries would be (1) the extent of surgical movement required for the correction of the complexity and also (2) the amount of extraction space utilization especially created during anterior segmental osteotomy surgery. Segmental osteotomy is primarily indicated when the discrepancy is defined by the following conditions: 1. Dental proclination requiring extraction space for the correction of anterior teeth inclination. 2. Moderate to severe crowding requiring extraction space for unravelling of crowding.

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Class I Bimaxillary retroclination Skeletal retrusion + No dental retroclination

Non-extraction + Bimaxillary advancement Jaw surgery

Upright retroclined teeth + Bimaxillary advancement Jaw surgery

Skeletal protrusion + No dental proclination

Skeletal retrusion + dental retroclination

Non-extraction + Bimaxillary set-back Jaw surgery

Maintain Class I molar relation + Positive overjet

Maintain Class I moral relation + Positive overjet

Fig. 7.1  Figure describing possible surgery options available for the resolution of skeletal Class I sagittal discrepancy

Class I SFOA Treatment Guidelines

Class I Bimaxillary proclination

All four first premolar extaction + Bimaxillary set-back Jaw surgery, maxillary anterior segmental osteotomy

Skeletal protrusion + dental proclination

Conside genioplasty for chin augmentation

Conside genioplasty for chin corection

56 7  Management of Skeletal Class I Malocclusion with Surgery-First Orthognathic…

7.3  Case Report

7.3

57

Case Report

A 20-year-old female presented with a chief complaint of unable to see her top front teeth when smiling. Extra-orally, she showed a concave profile, prominent chin, retrusive upper and lower lip, and a reverse smile arc (Fig. 7.2). Intra-orally, she showed a Class I molar and canine relationship and mild lower anterior crowding with overjet and overbite within normal limits (Fig.  7.3). Cone beam computed tomography scan (CBCT) confirmed the clinical findings (Fig. 7.4).

7.3.1 Treatment Objectives The objectives were classified into three main categories, and they are: 1. Skeletal objectives. (a) To correct the hypoplastic maxilla. (b) To correct the retrognathic mandible. (c) To correct the large chin. 2. Dental objectives. (a) To correct minimal crowding. (b) To maintain the upper and lower arch Class I relationship. 3. Soft tissue objectives. (a) To restore facial harmony. (b) To produce an aesthetically satisfactory face.

7.3.2 Surgical Plan Based on the clinical presentation and CBCT scan assessment, SFOA was planned for the correction of maxillo-mandibular complex (Figs. 7.5 and 7.6). A LeFort I osteotomy for the advancement of maxilla with clockwise rotation, and BSSO for

Fig. 7.2  Pre-treatment extra-oral images

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Fig. 7.3  Pre-treatment intra-oral images

Fig. 7.4  Pre-treatment CBCT images confirming the clinical observations

the advancement of the mandible, was planned, along with a reduction genioplasty for the correction of the prominent chin.

7.3.3 Treatment Progress All teeth were bonded, and a stainless steel ligature was tied passively in the upper and lower arches. The patient was subjected to surgery as planned. One week post-­ surgery extra-oral images showed fulfilment of surgery objectives with no change in

7.3  Case Report

59

Fig. 7.5  Extra- and intra-oral images taken just before surgery. Note: the brackets are ligated with a non-active ligature wire

Fig. 7.6  Surgical plan; clockwise rotation of the maxillo-mandibular complex having pivotal point in the middle of palatal plane (ANS to PNS) with advancement of the maxilla and mandible. Also, genioplasty was done to reduce the protrusive chin

the occlusal aspect (Fig. 7.7). The overall treatment time was 4 months from start to finish. Treatment results: post-treatment images (Fig. 7.8) and radiographs (Fig. 7.9) showed excellent aesthetic and occlusal results (Fig. 7.9).

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Fig. 7.7  Images taken at 1-week post-surgery showing fulfilment of surgery treatment objective

7.4 Conclusion

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Fig. 7.8  Post-treatment images showing pleasing outcome with stable results

Fig. 7.9  Post-treatment lateral cephalograph and orthopantomograph showing stable results

7.4

Conclusion

This chapter describes the skeletal Class I deformity treated with SFOA with intention to maintain the pre-treatment occlusion relationship. The key for successful management of skeletal deformity with Class I occlusion is to maintain the posterior buccal occlusion; every effort should be made to preserve the occlusion.

8

Management of Skeletal Class II Malocclusion with Surgery-First Orthognathic Approach

8.1

Introduction

Figure 8.1 explains the Class II skeletal deformity characterization in three-­ dimensional space and an effective surgical management plan to obtain stable aesthetic and functional results. Several surgical strategies could be employed for the resolution of skeletal Class II malocclusion, such as mandibular advancement, maxillary differential impaction, or a combination to produce a counterclockwise rotation of the maxillo-mandibular complex. In order to determine the suitability of appropriate treatment planning, it is essential to ascertain the type of skeletal Class II malocclusion and distinguish whether the skeletal Class II pattern arose from a single entity such as maxilla or mandible or a combination of both. One must also consider if there is a dental component contributing to the overall Class II problem. Three cases have been described in this chapter that each required their own individual different surgical plan. Various treatment options are described in Figs. 8.2, 8.3, and 8.4. Case 1 is a ‘retreatment case’ comprising of bimaxillary protrusion with severe chin retrusion that required MMC counterclockwise rotation. Case 2 is a severe skeletal Class II with deep curve of Spee and low mandibular plane angle which was corrected by mandibular advancement to create edge-to-edge bite and a counterclockwise rotation of the MMC. Case 3 is a Class II division 1 malocclusion having facial asymmetry, with buccal crossbite, heavily restored upper and lower posterior teeth, and was surgically treated with a three-piece LeFort I osteotomy and mandibular advancement. Temporary anchorage device was placed for the protraction of the second molar in the first molar extraction space.

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Vertical

transverse

Anterior open bite

moderate to deep mandibular curve of Spee

Scissors Bite

Cross bite

Protuded maxilla + Retruded mandible

Differential impaction of maxilla with clockwise rotation + BSSO advancement

Lower anterior segmental intrusion

BSSO advancement

Skeletal scissor bite > molar width

Skeletal cross bite > molar width

Skeletal cross bite ≤ molar width

Le Fort set-back+ BSSO advancement

Le Fort I set-back or Upper first premolar extraction + maxillary anterior segmental osteotomy

Fig. 8.1  SFOA treatment guidelines in three dimensions based on the degree of complexity

SFOA Treatment Guidelines

Sagittal

Protruded maxilla + normal mandible

Set-up occlusion in Class I relationship

Set-up occlusion in Class I relationship

Set-up occlusion Edge-to-edge incisor and establish posterior disocclusion

Consider SARPE

3-piece Le Fort I osteotomy of the maxilla.

To correct crossbite postoperatively

Set-up occlusion in Class I molar relation Or Class II in cases of upper first premolar extraction

Intrude posterior teeth, consider TAD’s

Intrude anterior teeth and allow eruption of posterior teeth

Set-up occlusion within the tooth movement envelope

consider creation of large positive overjet for correction of retrcolined lower incisors

Consider using TPA to correct bite post-operatively

64 8  Management of Skeletal Class II Malocclusion with Surgery-First Orthognathic…

8.1 Introduction

65

Fig. 8.2  Images illustrating surgical orthodontics in skeletal Class II predominantly defined by mandibular retrognathism (left side image). The Class II can be corrected by two ways: (1) straight advancement of the mandible alone (middle image) which could be done in a moderate Class II case requiring limited amount of mandibular advancement and (2) (right side image) counterclockwise rotation of MMC in severe retrognathic cases for achieving large amount of advancement, enhancing chin projection, and improving pharyngeal airway space

Fig. 8.3  Images illustrating surgical orthodontics in skeletal Class II with mandibular retrognathism, with deep bite and exaggerated curve of Spee. Perform counterclockwise rotation of mandible, and set up the bite in an edge-to-edge incisor relationship with posterior open bite. Postoperative intrusion of lower incisors for further counterclockwise rotation of mandible is done by cantilever arm mechanism with bilateral intrusion arms placed in the lower arch. The aforementioned mechanism will compensate for the post-surgery skeletal relapse with extrusion of upper and lower posterior teeth and also allows to maintain the vertical height achieved by jaw surgery

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Fig. 8.4  Surgical orthodontics in Class II mandibular retrognathism. Setting up the mandible in Class III and extraction of lower first premolars with anterior segmental osteotomy. The remaining extraction space could be utilized for orthodontic retraction. However, extraction of first premolars and anterior segmental osteotomy could produce periodontal problems such as fenestration and dehiscence at the segmental osteotomy site and, also, with no antagonist teeth at the posterior segment might lead to supraeruption of unopposed upper molar tooth leading to further periodontal and occlusion problems

8.2

Treatment of Various Skeletal Class II Cases

Case 1: A 26-year-old female presented with chief complaint of small chin and sticking out upper front teeth. She had orthodontic treatment during her teenage years and expressed dissatisfaction with the results. On examination, she showed short chin throat length, lip incompetence, a gummy smile, concordant smile arc, missing #14, 24, and 34, and a lower dental midline deviated to the left side by 2 mm in relation to the upper dental midline. Her upper anterior teeth were retroclined, and pharyngeal airway space was constricted. The cephalometric findings confirmed the clinical observation with SNA 77°, SNB 67°, ANB 10°, SN-MP 58°, UAFH/LAFH 42/58%, U1/SN 85°, and IMPA 87°. Two-jaw surgery: Counterclockwise rotation of MMC differential LeFort I osteotomy and BSSO.  For LeFort I, the pivotal point is at the anterior maxilla with superior repositioning of the anterior maxilla and inferiorly repositioning the posterior maxilla such that the MMC rotates in a counterclockwise direction. (Refer to Chap. 4 that explains further on pivotal points and advancement genioplasty.) The MMC counterclockwise rotation would upright the upper incisor angulation and a post-surgical occlusion set up in an anterior edge-to-edge relation with the remaining midline discrepancy that would be corrected in the post-surgical orthodontic treatment phase (Figs. 8.5, 8.6, 8.7, 8.8, and 8.9). Case 2: A 22-year-old female presented with a chief complaint of her upper front teeth forwardly placed and difficulty in eating with her front teeth. Extra-orally, she exhibited a convex profile, marked protrusion of upper lip, and reduced lower anterior facial height. Intra-orally, she showed 100% deep bite, Class II canine, and molar relationship. CBCT scan confirmed the clinical findings with skeletal pattern being hypodivergent and no temporomandibular joint aberrations. Two-jaw surgery: A two-jaw surgery was planned such that mandible was advanced to edge-to-edge bite with the creation of posterior open bite. LeFort I

8.2  Treatment of Various Skeletal Class II Cases

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Fig. 8.5  Pre-treatment extra- and intra-oral images

Fig. 8.6  Two-jaw surgery with counterclockwise rotation of MMC was planned. Refer text for further explanation

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Fig. 8.7  (First and second row) Post-surgery lateral cephalograph and intra-oral photos showing achievement of surgery objective. (Third row) 1-week post-op, minor early relapse was noted with anterior overbite of −2 mm and overjet of 0 mm. (Fourth row) At 8-month post-op, midline and anterior open bites were corrected by diagonal elastics and anterior vertical elastics, respectively

osteotomy with maxillary setback was planned for the correction of maxillary skeletal protrusion and also creation of an orthodontically treatable malocclusion (Figs. 8.10, 8.11, 8.12, 8.13, 8.14, and 8.15). Case 3: A 28-year-old female presented with a chief complaint of skewed upper front teeth. Extra-orally, she showed convex profile, recessive chin with chin puckering, asymmetric mandible with left side deviation, deep labial-mental fold, and an asymmetric smile. Intra-orally, there were a left-sided buccal segment buccal crossbite and heavily restored upper and lower posterior teeth with maxillary occlusal canting. Two-jaw surgery: The mandible was advanced to edge-to-edge bite, and a LeFort I, three-piece osteotomy was planned for the correction of maxillary skeletal protrusion and also for the buccal crossbite correction. This created an orthodontically treatable malocclusion post-surgery (Figs.  8.16, 8.17, 8.18, 8.19, 8.20, 8.21, and 8.22).

8.2  Treatment of Various Skeletal Class II Cases

69

Fig. 8.8  (Top row) Pre-treatment and 1-week post-treatment CBCT superimposition showing MMC counterclockwise rotation and genioplasty with anterior impaction of maxilla and counterclockwise rotation of maxilla, mandibular lengthening, and decreasing of gonial angle. (Middle row) 1-week post-surgery superimposed on post-treatment showing 2-mm relapse at chin point and extrusion of upper and lower dentition. Pre- and post-treatment superimposition CBCT showed slightly forward movement of maxilla, 15-mm mandible advancement, upright and intruded upper anterior teeth, extrusion of upper posterior teeth and lower anterior teeth

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Fig. 8.9  Post-treatment extra- and intra-oral images

8.2  Treatment of Various Skeletal Class II Cases

71

Fig. 8.10  Pre-treatment intra- and extra-oral images

Fig. 8.11  Planning is carried out such that a treatable malocclusion is established along with mandibular advancement and counterclockwise rotation of MMC. An edge-to-edge incisor relationship with 7-mm posterior open bite is created in the study models. The surgery plan is emulated with intra-oral images taken immediately post-surgery showing actualization of model surgery

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Fig. 8.12  Images taken at 2 months post-surgery. Bilateral intrusion arches were placed in the lower arch to intrude and upright the retroclined lower incisors. The cantilever mechanism will extrude the posterior teeth and intrude and upright the anterior teeth. The aforementioned tooth movement biomechanics is beneficial in this case, as the posterior teeth extrusion allows to close the posterior open bite and maintain the vertical height established during surgery, and also, in the anterior segment, intrusion and uprighting of anterior teeth will allow the mandible to further rotate in anticlockwise direction which will enhance the chin projection and ultimately aid in improvement of recessive chin

8.2  Treatment of Various Skeletal Class II Cases

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Fig. 8.14  Images taken at 8 months post-surgery showing fulfilment of treatment objectives

Fig. 8.13  Images at 6 months post-surgery. Vertical elastics were placed for settling of occlusion

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Fig. 8.15  (Top row) Pre-treatment and 1-week post-treatment CBCT superimposition showing advancement of the mandible as planned. (Middle row) Superimposition of 1-week post-surgery with post-treatment CBCT scans showing extrusion of posterior teeth. (Bottom row) Images of pre-treatment with post-treatment scans showing stable mandibular advancement (7  mm) and genioplasty (5 mm) (total of 12-mm advancement), maxillary setback, and extrusion of posterior teeth

8.2  Treatment of Various Skeletal Class II Cases

75

Fig. 8.16  Pre-treatment images showing Class II maxillary protrusion, mandibular retrognathism, and facial asymmetry. Intra-oral images showing Class II division 1 malocclusion, left side buccal segment scissors bite, heavy restorations of upper and lower posterior teeth. Maxillary occlusion showed maxillary right side up occlusal cant, and mandibular occlusion showed left side up

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Fig. 8.17  The surgical plan included LeFort I three-piece osteotomy to decrease upper intermolar width for the correction of left posterior segment scissors bite with extraction of bilateral upper right and left second premolars. BSSO for mandibular advancement and counterclockwise rotation with 2–3-mm posterior open bite. Note the maxilla is moved upward (crossed black lines) on the left side for the correction of maxillary occlusal canting

8.2  Treatment of Various Skeletal Class II Cases

Fig. 8.18  Images showing 1-week post-surgery showing fulfilment of objectives

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Fig. 8.19  Superimposition of pre-treatment and post-1-week CBCT images showing mandibular advancement and genioplasty of 10 mm. Also, levelling of the upper and lower occlusion, and the chin moved to the right. In addition to LeFort I setback and impaction, lengthening of mandible and genioplasty was achieved. Note the occlusion on the left side is moved up and more mandibular lengthening on the left

8.2  Treatment of Various Skeletal Class II Cases

79

Fig. 8.20  (Top row) Images showing 1-month post-surgery images with lower anterior intrusion carried out by bilateral intrusion arms. (Middle row) Images taken at 4-month post-surgery showing placement of TAD in the lower left segment for lower left second molar protraction in the extraction space. (Bottom row) Images showing settling elastics

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Fig. 8.21  Post-treatment extra- and intra-oral images

8.3 Conclusion

81

Fig. 8.22  One-week post-surgery CBCT images superimposition over pre-treatment images showing forward movement and upward rotation of mandible. One-week post-surgery CBCT images superimposed over post-treatment showed forward rotation of mandible, slightly right movement of mandible, extrusion of posterior teeth, and intrusion of lower anterior teeth with no mandibular relapse. Pre-surgery and post-surgery CBCT superimposition images showing 12-mm mandibular advancement and genioplasty with intrusion and retraction of anterior teeth

8.3

Conclusion

Skeletal Class II problems can be treated predictably with surgery-first approach. Moderate to severe cases requiring surgery necessitate meticulous evaluation of the facial complex. In order to formulate an effective treatment plan, the following three domains must be considered: 1. Dental considerations: Teeth positioning or repositioning plays an important role when considering a surgical plan. Case 1 is a retreatment case which has teeth previously extracted and the discrepancy has not been resolved. In this case, further extraction is not viable but may lead to detrimental effects. A surgery was planned to solve the skeletal issue that a camouflage orthodontic treatment plan

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was not able to resolve. Case 2 presents with a skeletal Class II with a severe deep bite and decreased lower facial height. No extractions were indicated, and the surgery was planned to correct the irregularity by the surgery alone. Case 3 is a composite of dental and skeletal problems further worsened by a mutilated dentition. The buccal crossbite was corrected by a three-piece LeFort I osteotomy with extractions of the upper first bicuspids. This allowed both the buccal crossbite and the maxillary protrusion to be addressed by the surgery. A thorough periodontal evaluation is imperative when contemplating intra-dental osteotomy to prevent untoward sequelae, like fenestrations and dehiscence from occurring. TAD was placed for the protraction of lower left second molar. 2. Skeletal considerations: Correction of skeletal Class II division 1 via surgery requires appropriate surgery design/planning (encompassing a greater expanse of problem list). (A complete list of do’s and don’ts is enumerated in Chap. 6.) 3. Soft tissue considerations: Lower lip position or entrapment, influence of counterclockwise rotation on pterygomasseteric sling, and the role of post-surgery occlusion on re-establishing soft issue harmony, neutral space, and on stability need to be addressed (refer to Chap. 6).

9

Management of Skeletal Class III Malocclusion with Surgery-First Orthognathic Approach

9.1

Introduction

This chapter describes the nuances involved in the management of Class III skeletal individuals treated with surgery-first orthognathic approach. Several factors have to be taken into account for the successful management of Class III cases that are subjected to SFOA without compromising on the final outcome. It is imperative that the orthodontist and surgeon involved in SFOA should closely follow the orthognathic surgery principles and also understand the limitations of orthodontic teeth movement. The chapter’s focus is on treatment guidelines for Class III skeletal malocclusion in three dimensions.

9.2

 FOA Treatment Guidelines in Three Dimensions Based S on the Degree of Complexity

Figure 9.1 describes SFOA treatment guidelines in three dimensions based on the degree of complexity. Three cases will be discussed in this chapter with moderate to severe forms of Class III skeletal patterns. After initial evaluation with the essential tools of assessment (refer to Chap. 2), a problem list is developed from a treatment plan based on SFOA principles.

9.3

Case Presentation

All three individuals displayed varying degree of skeletal Class III deformity. On clinical examination, Case 1 showed concave profile, increased lower anterior face height, hyperdivergent skeletal pattern, and a large mandible. Intraorally, Case 1 exhibited a Class III molar and canine relation, mild crowding of upper and lower anterior teeth, dental midlines matching, and reverse overjet of 3 mm. A cone beam

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computed tomography scan (CBCT) reveals the absence of skeletal asymmetry and no abnormality of the temporomandibular joint. Case 2, on clinical examination, revealed concave profile, severe Class III profile with increased lower anterior face height, shallow mentolabial sulcus, and a positive lip step. Intraorally, she showed severe crowding of upper and lower arch with bimaxillary proclination of teeth. Whereas, Case 3 demonstrated a very severe form of skeletal Class III with extremely hypoplastic maxilla, a large mandible, and excessive lower anterior face height. Also, intraorally, he demonstrated a severe anterior open bite with retroclined and crowded lower incisors and collapsed upper arch. The treatment objectives were classified into three main categories, and they are: 1. Skeletal objectives. (a) To correct the hypoplastic maxilla. (b) To normalize the prognathic mandible. 2. Dental objectives. (a) To upright the retroclined lower anterior teeth (in Cases 1 and 3). (b) To retract proclined upper and lower anterior teeth (in Case 2). (c) To correct a severely collapsed upper arch. (d) To alleviate upper and lower arch crowding. 3. Soft tissue objectives. (a) To restore facial harmony. (b) To produce an aesthetically satisfactory face.

9.3.1 Treatment SFOA comprises of only one active orthodontic phase (post-surgical orthodontic phase), as compared to conventional orthognathic surgery’s two phases of active orthodontic treatment (pre-surgical orthodontic treatment for decompensation, levelling and aligning, etc. and post-surgical orthodontic treatment). The pre-surgical orthodontic phase for SFOA which essentially is a non-active or at least a minimally active orthodontic phase is included for discussion for completeness. • Phase I: Pre-surgical orthodontics. • Phase II: Surgical phase. • Phase III: Post-surgical orthodontics.

9.3.1.1 Case 1 See Figs. 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 9.10, 9.11, 9.12, and 9.13. 9.3.1.2 Case 2 See Figs. 9.14, 9.15, 9.16, 9.17, 9.18, 9.19, and 9.20. 9.3.1.3 Case 3 See Figs. 9.21, 9.22, 9.23, 9.24, 9.25, 9.26, 9.27, 9.28 and 9.29.

9.3  Case Presentation

Sagittal

85 moderate retroclined lower + crowded lower incisors

segmental osteotony + BSSO set-back

Predined maxillary incisors

Lefort losteotony with clockwise rotation + BSSO set-back

severe retroclined and crowded lower incisors

Lower first premolar extraction + anterior segmental osteoery + BSSO set- back

Set-up occlusion in Class I relationship

Skeletal cross bite ≤ molar width

Set-up occlusion in Class III relationship + large positive overjet

Align lower incisors Utilizibg the large overjet

Align lower incisors Utilizibg the large overjet

To correct crossbite postoperatively

Cross bite SFOA Treatment Guidelines

Skeletal cross bite > molar width

transverse

Scissors Bite

Moderate to deep mandibular curve of Spee

Skeletal scissor bite > molar width

Anterior segmental osteotony

3-piece Le Fort I osteotomy of the maxilla.

Set-up occlusion within the tooth movement envelope

Consider using TPA to correct bite post-operatively

Consider SARPE

Set-up occlusion in Class I relationship

Lower incisers inruded + upper incisor extruded

Vertical

Anterior open bite

Differential impaction of maxilla with clockwise rotation + BSSO advancement

Set-up occlusion in Class I relationship

Intrude posterior teeth, consider TAD’s

Fig. 9.1  SFOA treatment guidelines in three dimensions based on the degree of complexity

Fig. 9.2  (Case 1) Initial images showing pre-treatment extra- and intra-oral photos of a female with Class III prognathic profile, Class III molar relationship, and moderate crowding in the upper and lower arch

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Fig. 9.3  Images showing intra- and extra-oral photographs just before surgery. Note, in this case, all four first premolars were extracted during the bonding appointment (1  week before the surgery)

9.3  Case Presentation

87

Fig. 9.4  CBCT scan and 3D photogrammetry images confirmed the clinical assessment clearly showing mandibular prognathism and increased lower anterior face height. Further, these images were used for 3D surgery planning

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Fig. 9.5  The final 3D prediction showing improved facial features along with establishment of orthodontically manageable malocclusion

9.3  Case Presentation

89

Fig. 9.6  Images showing establishment of two-point contact in the posterior region. Also, note the bilateral molar crossbite (post-treatment planning) is within the envelope of orthodontically treatable malocclusion

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Fig. 9.7  Images showing both maxillary and mandibular surgery planning done with the assistance of ‘3D Surgery Planning’ software. By applying 6DoF movements, the maxilla is fixed with reference to FHP, and subsequently the mandible is allowed to follow the maxilla’s planned position whilst making sure that at least two-point occlusal contact is achieved. In this case, a two-point contact is established with two points in the posterior region bilaterally at second molars, whilst at incisal area, no attempt was made to establish contact due to extreme instanding upper lateral incisors. In the anterior region, provisions were made such that the upper lateral incisor was in positive overjet relationship

9.3  Case Presentation

Fig. 9.8  Images showing intermediate and final surgical wafers

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Fig. 9.9 Images showing intra- and extra-oral photographs taken 1-week post-surgery. The planned 3D surgical simulation is successfully emulated in the patient. All the objectives of SFOA as enumerated in the text have been successfully achieved with minimal facial swelling. Anterior box elastics, posterior bilateral Class III, and vertical configuration settling elastics were placed immediately after the surgery in the operation theatre itself. Proper instructions were provided to the patient for the placement of the same. Note the elastics were placed on K-hooks with ligature wires in the upper and lower arches

Fig. 9.10  Images taken at seventh day post-surgery; the ligature wires were replaced with 0.016″ NiTi upper and lower arch wires

9.3  Case Presentation

93

Fig. 9.11  Nine months post-surgery, rectangular 0.017″ × 0.025″ TMA wires were placed in the upper and lower arches. Intra- and extra-oral photographs showing Class I molar and canine relationships along with the resolution of both skeletal and dental problems

Fig. 9.12  Intra- and extra-oral photographs showing post-treatment images with a balanced face and excellent Class I molar and canine relationship

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Fig. 9.13  Post-treatment CBCT images showing orthognathic skeletal relationship with normal occlusion

9.3  Case Presentation

95

Fig. 9.14  Initial images showing pre-treatment extra- and intra-oral photos of a female with Class III prognathic profile, Class III molar relationship, severe crowding, and bimaxillary proclination in the upper and lower arch

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Fig. 9.15  A bijaw surgery was planned using ‘3D surgery planning software’. A mandibular setback sagittal split osteotomy along with maxillary LeFort I advancement surgery was planned taking into account the 6DoF essential to resolve the skeletal problems associated with this patient

Fig. 9.16  Immediate post-surgery CBCT images showing orthognathic skeletal relationship establishment. However, the proclination of upper and lower incisors and severe crowding still need to be resolved; therefore, first bicuspid extractions were planned

9.3  Case Presentation

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Fig. 9.17  Images showing intra- and extra-oral photographs of patient at 8 months post-surgery. 0.017″ × 0.25″ TMA upper and lower arch wires are placed after the resolution of crowding. Note, the patient is ready for retraction of upper and lower anterior teeth

Fig. 9.18  At 18 months post-surgery, 0.017″ × 0.025″ SS upper and lower arch wires are placed. The proclination of upper and lower anterior teeth are corrected, along with completion of space closure

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Fig. 9.19  Intra- and extra-oral photographs showing post-treatment images with a balanced face and excellent Class I molar and canine relationship

Fig. 9.20  Post-treatment CBCT images showing orthognathic skeletal relationship with normal occlusion

9.3  Case Presentation

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Fig. 9.21  Initial images of a very severe Class III skeletal patient with severe anterior open bite, retroclined and crowded lower incisors

Fig. 9.22  Upper and lower 0.014″ NiTi wires were placed in the upper and lower arch

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Fig. 9.23  Model surgery was performed to predict the surgery outcome. Based on the cephalometric and clinical assessment, the following surgeries were planned: LeFort I osteotomy, bilateral sagittal split of the mandible, and mandibular anterior segmental osteotomy. The maxilla was rotated clockwise to upright the excessive upper incisor inclination such that the inclination lies within the orthodontically treatable perimeter. The lower first premolars were extracted and anterior segmental osteotomy was performed, and the occlusion was set up in a Class III molar relationship with a large incisor overjet during surgery. This creation of large incisor overjet would enable decrowding of severely crowded lower anterior teeth and, also, would enable uprighting of the same. Note the upper second molars are still in crossbite even after surgery planning. A transpalatal arch will be placed to correct the crossbite post-surgery

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Fig. 9.24  Radiographs taken immediately post-surgery showing achievement of surgical objectives. A constricted with a buccal root torque transpalatal arch was placed across bilateral upper second molars to correct the crossbite

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Fig. 9.25  A chin cap was applied to prevent the mandibular skeletal relapse in the first 3 months postoperatively. The retroclined lower incisors and excessive overjet were then decompensated and aligned postoperatively to obtain a normal inclination and overjet

9.3  Case Presentation

Before Surgery

1-wk post-surgery

3 months

4 months

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Before Surgery

1-wk post-surgery

3 months

4 months

6 months

Fig. 9.26  Images showing correction of dental malocclusion within a period of 4–6 months. The most dramatic change was noticed in the lower anterior crowding alleviation and buccal crossbite correction of upper second molar

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Fig. 9.27  Bilateral cantilever mechanics was used in the lower arch for the uprighting and intrusion of lower anterior teeth. 0.017″ × 0.025″ TMA wires were placed in the upper and lower arch wires

Fig. 9.28  Patient images showing after space closure. TPA was placed in the lower arch for the correction of uprighting of bilateral second molar

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Fig. 9.29  Intra- and extra-oral photographs with lateral cephalograph showing achievement of treatment objectives

9.4

Conclusion

Skeletal Class III deformities generally require surgery for both the maxilla and mandible for the correction of skeletal problem. This chapter shows the complexity of management with emphasis on setting up a ‘transitional occlusion’ such that postoperatively adjunctive orthodontic treatment can be utilized to transfigure the orthodontically treatable malocclusion into the solid final occlusion.

Management of Skeletal Asymmetry with Surgery-First Orthognathic Approach

10

There is no symmetry in nature. One eye is never exactly the same as the other. —Edouard Manet

10.1 Introduction Although facial symmetry has been rated as a central key for attractiveness [1], it is a rarity for a human face to be perfectly symmetrical. The correction of maxillo-­ mandibular jaw asymmetry primarily depends upon prompt diagnosis of the problem and a clear differentiation between relative (subclinical) normal asymmetry from obvious asymmetry arising from a genetic predisposition (congenital), acquired (injury, disease), and developmental conditions (unknown aetiology) [2]. Facial asymmetry should be determined whether it arises from dental, skeletal, muscular, functional, or a combination of factors. This is carried out by judicious application of various diagnostic tools like clinical assessment (measurement), photographic assessment, and radiographic assessment leading to a collective and definitive diagnosis of the problem [3]. Once determined that the asymmetry in the maxillo-mandibular complex (MMC) is due to skeletal and dental aberrations, the asymmetry should be further categorized into maxilla alone, mandible alone, or a combination of the both. Several imaging modalities are used to measure and define the MMC in terms of six degrees of freedom in three-dimensional space including translation coordinates axes (sagittal, transverse, vertical) and three rotational axes (pitch, roll, yaw). Chapter 4 provides a comprehensive description of 3D techniques and modalities that have the capability to assess the MMC. The chapter further elucidates on the assessment of asymmetry both on 2D and 3D imaging system in the form of identifying various landmarks and planes that can quantify the discrepancy

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and also aid in formulating an effective treatment plan. This chapter will focus on MMC asymmetry pertaining to (1) maxilla and mandible and their interrelationship in the form of midline discrepancy (midsagittal plane), (2) influence on the menton or chin position, and (3) maxillary cant and occlusal plane and their subsequent influence on the MMC in general. Several authors have proposed various methods to assess the midline discrepancy, of which two methods are of prime importance [4–7]: 1. Landmark-based asymmetry assessment using specific landmarks such as nasion, anterior nasal spine, and basion. 2. Model mirroring in midsagittal plane, in which the unaffected or the symmetrical side is superimposed or overlaid on the asymmetrical side using fully automated, voxel-wise rigid registration of the cranial base and, subsequently, the actual discrepancy computed. The methods are utilized in describing two cases of asymmetry that were managed with surgery-first approach. The two cases present with similar asymmetry, but on careful observation and evaluation, they are defined by two different types of asymmetry with varying maxillary occlusal canting. In Case 1, the asymmetry is defined by uniform maxillary canting (anterior and posterior occlusal canting are in the same plane and parallel with reference to Frankfort horizontal plane, FHP). In Case 2, the maxilla is canted in two planes (anterior region does not exhibit any canting, and posterior region has a cant with reference to FHP). This discernment leads to different treatment plans albeit almost seemingly similar looking asymmetry.

10.2 C  ase 1: A Maxillary Occlusal Cant Extending Anteriorly to Posteriorly: Its Influence on MMC and on Subsequent Treatment Planning A 24-year-old male presented with chief complaints: large twisted lower jaw and difficulty in chewing. Extra-orally, he presented with a concave profile, asymmetrical mandible with a left-sided chin deviation, increased lower anterior facial height, positive lip step, asymmetrical smile line, and a shallow submental fold (Fig. 10.1). Intra-orally, he showed Class III molar and canine relationship with the presence of mild anterior crowding (Fig. 10.1). Cone beam computed tomography scan (CBCT) showed skeletal asymmetry of the mandible with a chin deviation of 7 mm to the right side (Fig. 10.1). The type of asymmetry (skeletal and dental) was ascertained by both clinical and radiographic (CBCT) evaluations (Fig. 10.2). Surgical plan: From the clinical presentation and CBCT scan evaluation, it was apparent that the mandible was skewed to the left side and the Class III deformity was primarily due to a prognathic mandible and a asymmetric maxilla where the

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Fig. 10.1  Case 1: pre-surgical intra- and extra-oral photographs and CBCT images showing asymmetry

asymmetry exists in both the vertical and anteroposterior planes. Surgery-first approach was planned for the correction of maxillo-mandibular complex, and the plan was simulated using face-bow transferred study models mounted on a semiadjustable articulator (Fig. 10.3). Treatment progress: All teeth were bonded, and 0.014″ Sentalloy wires were placed in the upper and lower arches. Patient proceeded with surgery as planned. One-week post-surgical extra-oral images and CBCT images showed fulfilment of

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Fig. 10.2  The asymmetry is predominantly defined in terms of MMC roll rotation. To evaluate (photographic evaluation) roll relative to soft tissues (top row images), intercommissural line is used in reference to intercanthal line. On smiling, a positive roll with the left side is raised upward, and the right side is lowered in relation to the intercommissural line that is evident. Radiographic evaluation (using CBCT images) (middle and bottom row images) showed, under the influence of positive roll of the maxilla, the menton has deviated in the left direction. A negative yawing (intergonial plane) (left-side movement) indicating lower anterior yaw relative to the direction of menton deviation. Furthermore, evaluation of the anterior and posterior maxillary cant showed the roll is similar and parallel to each other in both anterior and posterior regions of the maxillary occlusion. The same form of canting is emulated in the mandibular occlusion also

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Fig. 10.3  Top images showing articulator mounted models exacting the clinical and radiographic assessments. (Bottom images) A double jaw surgery (LeFort I and bilateral sagittal split osteotomy) was planned to correct the maxillo-mandibular complex primarily focussing on the role and yaw rotation. Once the maxilla’s roll rotation was corrected by impacting maxilla on the right side (slanted black lines), subsequently, mandible yawing was corrected with asymmetrical bilateral sagittal setback (more setback on the right side in comparison to left side) such that upper and lower arch dental midlines were matching in the midsagittal plane (red vertical line). Note the achievement of Class I molar and canine relation. Furthermore, using CBCT images, a sliding (to the right side) and advancement genioplasty were planned to further correct the anterior yawing and recessive chin (shallow submental sulcus)

surgery objectives (Figs.  10.4 and 10.5). One-month post-surgery, 0.016  ×  0.022 Sentalloy arch wires were placed for further levelling and anterior vertical elastics for settling. At 3-month post-surgery, lower intrusion arms were placed, and the case was finished with second-order bends (Fig. 10.6). The overall treatment time was 6  months from start to finish. Treatment results: post-treatment images (Fig. 10.7) and CBCT (Fig. 10.8) showed excellent aesthetic and occlusal results (Fig. 10.8). Pre- and post-treatment superimposition of CBCT images showed correction of Class III to Class I skeletal relation with resolution of roll and yaw rotations.

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Fig. 10.4  One-week post-surgery extra- and intra-oral images showing fulfilment of surgery objective

10.3 C  ase 2: Differential Anterior and Posterior Region Maxillary Occlusal Cant: Its Influence on MMC and on Subsequent Treatment Planning A 19-year-old male reported to the orthodontic clinic with a chief complaint of twisted jaw and difficulty in eating. On examination, CBCT scan and extra-oral images showed severe Class III profile with maxillary hypoplasia, mandible exhibiting left-sided deviation, and no temporomandibular joint abnormality (Fig. 10.9). Intra-oral images revealed Class III molar with Class III canine relation on the right side and Class II molar and canine relation on the left side with positive overjet on the right and a reverse overjet on the left. She showed a moderate upper incisor proclination and a moderate upper and lower crowding with an acute nasolabial angle (Fig. 10.9). Using CBCT images for evaluation of the occlusal canting, the anterior occlusal aspect showed canting and was parallel to the FHP. The posterior occlusal aspect showed a positive roll with the left side raised and the right side lowered. The skewing of the mandible was partly influenced by the roll rotation of the maxilla and was

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Fig. 10.5  One-week post-surgery CBCT images (top row images) showed resolution of the problem. One-week post-surgery CBCT images were superimposed on pre-surgery images (bottom row images). Corrections could be appreciated in MMC rotation and mandibular yaw rotation with chin centred (midsagittal plane)

largely due to the yaw rotation of the mandible itself, unlike Case 1, where the asymmetry is defined by the combination of maxilla-mandibular complex’s roll and yaw rotation. This aforementioned discernment plays an important key during surgery planning. Surgical plan: Bimaxillary surgery with surgery-first approach was planned. LeFort I impaction to correct the MMC role rotation and mandibular asymmetrical setback to correct the yaw rotation of mandible. Further, if required, (1) advancement genioplasty would be performed based on the amount of setback achieved during the surgery, and (2) bilateral upper and lower first premolars will be extracted for the correction of teeth proclination and crowding (Fig. 10.10). The dentition was bonded with 0.022″ preadjusted brackets. 0.014″ Sentalloy wire was placed in the upper and lower arches (Fig. 10.11). One-week post-surgical extra-oral images and CBCT images showed fulfilment of surgery objectives (Fig. 10.12). At 1 month, there was further improvement in the occlusion on the left side (Fig. 10.13). A transpalatal arch was placed in the upper arch across bilateral second molars to correct the crossbite (Fig. 10.14). The overall treatment time was 8  months. Treatment results: post-treatment images and CBCT showed excellent aesthetic and occlusal results. Pre- and post-treatment superimposition of CBCT images showed correction of Class III to a Class I skeletal relationship with resolution of roll and yaw rotations (Figs. 10.15 and 10.16).

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Fig. 10.6  Intra-oral images showing in between treatment at 1  month (top images), 2  months (middle images), and 3 months (bottom images) post-surgery

10.3  Case 2: Differential Anterior and Posterior Region Maxillary Occlusal Cant: Its…

Fig. 10.7  Post-treatment extra- and intra-oral images

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Fig. 10.8  (Top row images) Superimposition of 1-week post-surgery (green colour) CBCT images on post-surgery images (red colour) showed most of the surgery objectives were maintained and also results were stable; however, extrusion of upper dentition was also noted which made the mandible slightly moved to the left. (Bottom row images) Superimposition of pre-­ treatment (grey colour) and post-treatment (red colour) images showed great improvement of mandibular asymmetry, maxillary occlusal cant, and decrease of vertical facial height

10.3  Case 2: Differential Anterior and Posterior Region Maxillary Occlusal Cant: Its…

Fig. 10.9  Pre-treatment intra- and extra-oral photos with CBCT images

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Fig. 10.10  The asymmetry is partly defined in terms of maxilla roll rotation and mandible yawing. The surgery was planned to correct both roll and yaw with achievement of a treatable malocclusion. The roll rotation of maxilla was corrected by LeFort I minimal impaction, and yawing was corrected by asymmetrical mandibular setback. Note, due to the varied posterior occlusal canting, left-side posterior teeth do not have an occlusion with antagonist teeth, especially, at the second molar region. A transpalatal arch will be used to correct the second molar crossbite

Fig. 10.11  Pre-surgery bonding and banding were done with no bracket on the bilateral upper and lower first premolars. The brackets were not bonded on the aforementioned teeth so that, if required, those teeth will be extracted post-surgery, after evaluation of teeth inclination from post-­ surgery CBCT

10.3  Case 2: Differential Anterior and Posterior Region Maxillary Occlusal Cant: Its…

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Fig. 10.12  One-week post-surgery showing improvement of mandibular asymmetry. Note sliding advancement genioplasty was performed to correct the yawing and recessive chin

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Fig. 10.13  One-month post-surgery showing improvement of mandibular asymmetry

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Fig. 10.14  Intra-oral images showing in between treatment at 2 months (top images), 3 months (middle images), and 4 months (bottom images) post-surgery. A constricted transpalatal arch with buccal root torque was placed across bilateral upper second molar to correct the crossbite

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Fig. 10.15  Post-treatment extra- and intra-oral images

Fig. 10.16  (Top row images) Superimposition of 1-week post-surgery (green colour) CBCT images on post-surgery images (red colour) showed fulfilment of the surgery objectives. (Bottom row images) Superimposition of pre-treatment (grey colour) and post-treatment (red colour) images showed stable results

References

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10.4 Conclusion Successful management of facial asymmetry with surgery-first orthognathic approach depends on thorough evaluation of the asymmetry, in terms of skeletal and dental patterns, and its influence on the maxillo-mandibular complex. The occlusal canting and its cause must be ascertained with regard to the influence on the MMC in three-dimensional space.

References 1. Brookes M, Pomiankowski A.  Symmetry is in the eye of the beholder. Trends Ecol Evol. 1994;9(6):201–2. 2. Thiesen G, Gribel BF, Freitas MPM. Facial asymmetry: a current review. Dental Press J Orthod. 2015;20(6):110–25. 3. Cevidanes LH, Alhadidi A, Paniagua B, Styner M, Ludlow J, Mol A, et al. Three-dimensional quantification of mandibular asymmetry through cone-beam computerized tomography. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2011;111(6):757–70. 4. De Momi E, Chapuis J, Pappas I, Ferrigno G, Hallermann W, Schramm A, et al. Automatic extraction of the mid-facial plane for cranio-maxillofacial surgery planning. Int J Oral Maxillofac Surg. 2006;35(7):636–42. 5. Cevidanes LH, Heymann G, Cornelis MA, DeClerck HJ, Tulloch JC.  Superimposition of 3-dimensional cone-beam computed tomography models of growing patients. Am J Orthod Dentofac Orthop. 2009;136(1):94–9. 6. Xia JJ, Gateno J, Teichgraeber JF, Christensen AM, Lasky RE, Lemoine JJ, et al. Accuracy of the computer-aided surgical simulation (CASS) system in the treatment of patients with complex craniomaxillofacial deformity: a pilot study. J Oral Maxillofac Surg. 2007;65(2):248–54. 7. Cevidanes LH, Styner MA, Proffit WR. Image analysis and superimposition of 3-dimensional cone-beam computed tomography models. Am J Orthod Dentofac Orthop. 2006;129(5):611–8.

Pre- and Post-surgery Patient Care Checklist and Patient Instruction

11

Checklists seem to provide a protection against such failures. They remind us of the minimum necessary steps and make them explicit. They not only offer the possibility of verification, but also instill a kind of discipline of higher performance. —Atul Gawande, The Checklist Manifesto

11.1 Introduction In order for SFOA to result in a successful patient-centred outcome, it is of paramount importance that all stages of the process must be carefully planned and considered. The pre-surgical and post-surgical management can be made efficient by employing checklists to ensure no steps are missed. Checklists also serve as an adjunctive assessment tool that can assist in the evaluation of the case complexity at the examination and diagnosis stage. The success of SFOA is also dependent on the participation of the patient and care giver. This is very much like orthodontic treatment. The dos and don’ts before and after surgery need to be adequately conveyed. Only then can we minimize or even eliminate unwanted sequelae and ensure the success of SFOA.

11.2 P  re- and Post-surgery Checklist: Category, Conditions, Assessment Tools, and Management Plan Adequate pre-surgery and post-surgery patient care comprises of (1) anticipatory evaluation of impending conditions that may compromise the surgical outcome, (2) use of the possible tools of assessment to rule out the conditions, and (3) and execution of an effective management plan in order to curtail the conditions.

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Pre-surgery

Surgery

Orthodontic assessment

Social support

Preoperative anxiety

Medication/ anaesthesia clearance

Patient’s informed consent

Category Systemic evaluations

•  Lack of emotional support  –  Empathy, love, trust support •  Lack of guidance/instructional support  –  Appropriate instructions, advice, suggestions •  Lack of self-appraisal support  –  Basic self-evaluation information •  Lack of instrumental support  –  Tangible aid and service •  Bracket and band breakage •  Orthodontic ligation •  Surgical splint fit •  Surgical hooks/K-hook robustness •  Third molar •  Bone conditions •  TMJ evaluation •  Ulcers, lip drying

• Pain • Infection • Swelling •  Gastric emptying/bowel movements •  Infective endocarditis •  Previous unpleasant dental experiences • Sleeplessness •  Nervousness, apprehension • Helplessness

Conditions •  Cardiovascular conditions •  Respiratory and airway •  Bleeding diathesis •  Chronic systemic illness •  Occult disorder • Allergy •  Signed informed consent •  Identify patient’s needs, values, and goals

•  Addressing the condition

•  Addressing the condition •  Removal of third molar 3–6 months prior to surgery •  Defer surgery until TMJ issue is resolved

•  Clinical evaluation

•  Radiographic evaluation •  Clinical evaluation

•  Medical outcomes study social support survey (MOS-SS) •  Adequacy of social support •  Patient-reported quality of life (PRQL) •  Dental impact of daily life •  Activities of daily living (ADL)

•  Anxiety assessment (Spielberger State-Trait Anxiety Inventory (STAI), and the Multiple Affect Adjective Checklist (MAACL)) •  Psychological screening •  Level of knowledge of the procedure

Management plan •  Referral to appropriate specialist •  Defer surgery until conditions are resolved or under control •  Re-evaluate conditions •  Seek consent to treat from the treating doctor •  Anti-allergy medication •  Evaluate ethical, legislative conditions •  Contingency plan for risks, alternatives, uncertainties • Analgesics •  Antiplatelet medications •  Prophylactic antibiotics •  Amnesia enhancement drugs •  Reduction of volume of gastric and pH •  Consider deferring surgery if the anxiety is not curtailed •  Antianxiety medication (barbiturates) •  Explanations of procedures in non-jargoned language •  Enhancing coping skills •  Appraisal of surgical procedures •  Emotional, practical, and informational support from family and friends •  Association and close network with family members

Assessment tools •  Arterial blood gas analysis •  OSA rule out •  Complete blood count • Electrocardiogram •  Chest radiograph •  Allergy test •  All components/parts of informed decision-making •  Right information •  Shared decision-making •  Pain questionnaire •  Culture tests/immunoassays •  Clinical assessment

Table 11.1  Pre- and post-surgery patient care checklist with category, conditions, assessment tools, and management plan

126 11  Pre- and Post-surgery Patient Care Checklist and Patient Instruction

Post-surgery

•  Dental occlusion •  Guiding elastics difficult to place •  Positioning of surgical splint •  Bracket and band fixation evaluation

•  Bone plating incorrect •  Damage to alveolar segments •  TMJ malposition •  Excessive facial swelling • Bleeding •  Intermaxillary fixation (IMF) needs to be removed

Orthodontic assessment

Surgery

•  Mental health condition •  Emotional problem •  Body dysmorphic disorder (BDD) •  Comparing body parts to others’ appearance •  Camouflaging body parts •  Suicidal thoughts/tendency Postoperative pain •  Face—lips, cheeks, muscles management  –  Bruised face, tightness of jaws muscles, dry/ cracked lips, sore lips •  Ear, nose, throat  –  Nasal congestion, earache/irritated throat •  Teeth, alveolus, TMJ  –  Sore teeth  –  TMJ pain •  Foul odour Oral prophylaxis •  Excessive plaque accumulation requirements/ •  Food and beverage unable to clean guidance • Bacteraemia •  Gingival and periodontal inflammation •  Weight loss Postoperative nutrition (fluid and • Constipation electrolyte balance) • Hypovolaemia • Depression • Vomiting •  Oliguria, confusion, and tachypnoea

Mental/cognitive assessment

•  Radiographic evaluation •  Clinical evaluation

•  Post-surgery radiographic assessment •  Post-surgery clinical assessment

•  Assess occult bleeding •  Evaluate fluid loss via drains •  Assess excess bleeding intraoperatively and postoperatively

•  Present Pain Intensity (PPI) •  Visual Analogue Scales (VAS) of the McGill Pain Questionnaire •  Frequency, duration, and intensity assessment •  Underlying pathology assessment •  Sensations and pressure evaluation •  Rule out HSV-I breakout •  Oral hygiene evaluation •  Identify source of infections •  Wound healing evaluation

•  Posttraumatic stress disorder (PTSD) •  Trauma Screening Questionnaire (TSQ) •  Body dysmorphic disorder questionnaires •  Level of Exposure-Dental Experiences Questionnaire (LOE-DEQ)

•  Professional oral cleaning •  Oral toileting/brushing technique (oral irrigators and electric brushes) •  Reinforcing oral hygiene instructions •  Oral rinses (mouth washes) •  Engage appropriate bleeding control protocol •  Parenteral nutrition •  Oral liquid nutritional supplements •  Patient’s progress assessment with maxillofacial dietician •  Implement measures to counter vomiting •  Encouragement of elastic application •  Bracket and band fixation as early and much as mouth opening allows •  Consider re-surgery •  Initiate orthodontic treatment as early as possible •  Addressing the condition •  Consider re-surgery •  Provide adequate instructions and instruments for the recovery/postoperative care team to cut the IMF wire in the case of emergency

•  Ensure appropriate referrals for patients with emotional or psychiatric problems •  Cognitive behavioural therapy •  Antidepressant medications •  Psychoeducation, self-help books •  Support groups and websites •  Plan effective pain management •  Sepsis control •  Nasal decongestant •  Postoperative neurovascular assessment and monitor •  Consider antiviral therapy (acyclovir)

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Table  11.1 discusses some of the pre- and post-surgery conditions, such as systemic factors, patient’s informed consent, medication/anaesthesia clearance, preoperative anxiety assessment, social support, orthodontic, and surgery assessment.

11.2.1 Systemic Conditions, Medication/Anaesthesia Clearance Systemic evaluation is perhaps the most important element that determines the associated overall surgical risk and outcome of the surgery. Conditions like heart diseases, respiratory disease, and liver and renal functions should be assessed and considered in relation to risk when performing any surgery, along with a thorough assessment of allergies and undesirable medication side effect [1]. Routine preoperative tests are used to assess several aspects like pre-existing conditions, identify appropriate referrals, predict postoperative complications, and formulate a comprehensive management plan [2]. Current recommended guidelines should be followed, i.e. American College of Cardiology/American Heart Association (ACC/ AHA) recommends comprehensive guideline on perioperative cardiovascular evaluation [3]. Before using preoperative tests, it is practical to ascertain proper ‘history’ and comprehensive ‘physical examination’, and once these two are conducted correctly, studies suggest that as much as 70% of preoperative testings are unnecessary [4–6].

11.2.2 Psychological Assessment The patient’s objective of opting for jaw surgery should be considered with a psychological perspective with regard to patient’s fears, apprehensions of surgery which has to be appropriately addressed in order to achieve a successful execution of the treatment plan [7]. Patients should be educated about the transitional malocclusion following post-surgery in SFOA and difficulty associated with chewing with a possible aggravation of postoperative anxiety [7, 8]. Prior to surgery, psychological preparation in the form of addressing previous unpleasant dental experience, postoperative major changes in facial aesthetics, and the challenges associated with adjusting to the new face not only motivate the patient but also allow the patient to manage any anxiety issues and enhance the patient-doctor rapport. Anxiety assessment tests should be judiciously used to determine the associated anxiety, stress levels, knowledge, attitude and behaviour towards jaw surgery, and degree of exposure of previous traumatic events (Table 11.1). If the need arises, the patient should be referred for professional counselling in order to successfully manage the anxiety associated with the jaw surgery.

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11.2.3 Mental/Cognitive Assessment Body dysmorphic disorder (BDD) or dysmorphophobia is a body-image perception mental disorder characterized by persistent dislike or finding fault in some part of their body to such extreme extent that the affected person takes exceptional measures to hide or camouflage the perceived dysmorphic part [9, 10]. Several causes eliciting this aforementioned mental disorder need to be taken into account before the actual contemplation of jaw surgery. Literature suggests that patient affected with BDD seek aesthetic surgical enhancement at a prevalence rate as high as 15% [11]. Also, studies have shown that individuals with BDD repeatedly consult aesthetic surgeons to change their appearance and often do not benefit or show improvement in their condition even after performing multiple procedures [12]. It is prudent to rule out BDD during the initial evaluation including symptom profile, comorbidity patterns with depressive disorders, sociocultural factors, and neurological pattern and must be further referred for pre-surgical psychological counselling or psychiatric treatment. Studies have shown that individuals with BDD greatly benefit from ‘pharmacologic treatment’ involving selective serotoninergic antidepressants (fluoxetine and fluvoxamine) and tricyclics (clomipramine). These patients also show improvement with ‘psychological intervention’ such as cognitive-behaviour therapy that aims at altering certain specific beliefs and long-held assumptions that underline the BDD [13].

11.2.4 Social Support Several studies have shown that strong social support in the form of emotional and informational support significantly increases positive outcomes as opposed to patients that have lower levels of social support resulting in worse outcomes. Enhanced social associations have had a significantly lower levels of post-surgery pain levels, decreased administration of opioid (narcotic) pain medications, and a faster recovery rate after surgery [14, 15]. Appropriate surveys or questionnaires should be administered prior to surgery to assess the extent of preparedness of a patient in terms of social well-being and adequacy of social support. Provisions should be made to identify and address the psychosocial barriers that preclude the full participation of the patient. The multidisciplinary team should disseminate useful information pertaining to surgery and various postoperative coping skills such so that the patient can coherently participate in the process. Support groups, website links with comprehensive information, a hospital-based support system (phone contact number, mail address), and a qualified social worker information are some of the essential and supplemental support systems that should be provided to the patient and care givers for effective, impactful, and meaningful support. The aforementioned guidance enhances the autonomy of the patient which in

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turn positively influences the recovery as the knowledge allows the patient to be better equipped [16].

11.2.5 Postoperative Nutrition (Fluid and Electrolyte Balance) During the postoperative recovery phase, a patient’s body undergoes a period of limited supply of nutrition or starvation due to limited mouth opening, lack of appetite, pain and discomfort, and delirium. If nutrition is not supplied, the body switches to a ‘state of catabolism’ (breakdown of fat, protein, dehydration synthesis, and endergonic reaction) in order to maintain a minimum basal metabolic rate. Postoperative nutrition deterioration leads to alteration in body composition, weight loss, reduction of total body water, fat and protein decrease, and a lean body mass [17]. Some of the causes for the aforesaid conditions are enumerated in Table 11.1. Adequate nutritional support can substantially reduce postoperative morbidity and length of hospital stay [18]. A study concluded that the addition of a high calorie liquid supplement to the dietary schedule helped the postoperative recovering patient replenishes the nutrition level [17].

11.2.6 Patient’s Informed Consent Patient’s informed consent forms should contain all components of informed consent with full disclosure of the nature of procedure and a comprehensive plan such that the patient can make an informed decision to proceed with the surgery. Every informed consent should encompass three basic tenets of ethical practice, namely, (1) preconditions, (2) information, and (3) consent, and essentially should be based on best practices. The healthcare provider must disclose information including the benefits and risks associated with the procedure and the possible alternatives in layman’s terms a non-jargon-based language [19, 20].

11.2.7 Postoperative Pain Management Early and effective postoperative pain management increases the possibility of early mobilization, enhances patient comfort, and decreases risk of morbidity with reduced incidence of prolonged neuropathic pain which results in a timely or even an early discharge. In jaw surgery patients, postoperative pain can emanate from three distinct areas, namely, (1) face (lips, cheeks, and muscles); (2) ear, nose, and throat; and (3) teeth and TMJ (Table 11.1). The pathophysiology, severity, and consequences of pain should be assessed as early as possible by using both subjective and objective assessment methods. Most effective pain control therapeutic

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modalities should be discussed and administered after evaluating the nature of the pain, type of medication, most feasible route of administration, adverse effects, potential benefits, and therapy duration [21, 22].

11.2.8 Oral Prophylaxis Requirements/Guidance Poor oral hygiene poses as a risk factor for postoperative wound infection [23]. Bacteraemia detected in patients that underwent jaw reconstruction surgery showed a predominance of streptococci viridans isolated from the infection. Such bacteraemia induced infective endocarditis in patients with congenital or acquired cardiac anomalies which could lead to a potential life-threatening situation [24]. Studies have shown that good oral care reduced the microorganism’s number which in turn led to decreased incidence of bacteraemia [25]. Prior to surgery, individuals undergoing jaw surgery must be given proper oral hygiene instructions, importance of oral toilet and the maintenance of oral hygiene post-surgery. All efforts should be made to evaluate oral hygiene with identification of source of infections, if any, and appropriate measures should be taken to counter them (Table 11.1).

11.2.9 Orthodontic and Jaw Surgery Orthodontic-related checklist is enumerated in Table  11.1. A comprehensive pre-­ surgery orthodontic assessment is a prerequisite for achieving a consistently high-­ quality surgical outcome. The orthodontic checklist pertains to three domains: (1) bracket and wire, (2) tooth movement, and (3) surgical splint assessments. The problems encountered during orthodontic phase of SFOA are explained, in detail, in Chap. 12. Some of the important medical conditions and its implications on pre- and post-­ surgery are mentioned in Table  11.1 along with the appropriate management.

11.3 I nstructions for Patients and Care Givers: Dos and Don’ts The dos and don’ts encompass a plethora of settings for pre- and postoperative considerations, such as general well-being and diet, oral hygiene, physical activity or ambulatory care, psychosocial response, and pain management/wound recovery/ swelling for effective management of the patient. The authors have enumerated dos and don’ts for patients and care givers’ ease of understanding (Fig. 11.1).

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Dos and don'ts

Before surgery

Dos

Instructions

After surgery

Don’ts

Don’ts

• Carefully consider and evaluate hospital discharge, home care, and post-surgery rehabilitation plan. • Call the clinic for a follow-up visit • Wear the elastics as directed, if in doubt, inform the clinic ; ✓ Use mirror to wear elastics ✓ Use hooks to place the elastics ✓ Consider additional help • If the bite wafer is in place, follow the instructions on how to manage the wafer

• Not following instructions • Staying alone • Having negative thought, not communicating

• Immediate post-surgery to 1 week ✓ Liquid diet ( soup) ✓ Drink plenty of water ✓ Maintain sufficient hydration ✓ Use toddler cups ( sippy cups) to drink or use squeeze bottles that squirt fluid. • Week 1 to week 3 ✓ Follow soft diet (semi-solid) ( mashed potatoes, fish, mashed banana) ✓ Cold foods ( yoghurt, plane ice cream) ✓ Protein shakes and multivitamin syrups • Weeks 3-4 onwards ✓ Soft to normal diet (avoid eating hard and chewy food) ✓ Noodles, rice (congee) , soft-bread ✓ Sliced apple, orange

• Biting on hard , crunchy, and chewy food (e.g., candies, popcorn, peanuts, meats) • Shower with hot water for at least a couple of days • alcoholic beverages, Smoking

• Not following instructions • Eating sticky food

• Warm saline rinses using syringes • Anti-bacterial, antiseptic mouth rinse (Chlorhexidine, Listerine) • Use a child-size tooth brush until mouth opening is limited • Apply generous amount of lip balm or petroleum jelly on lips too keep it from drying and bleeding • Use tongue cleaner, preferably a small size • Use additional oral swabs to keep your mouth clean • Stock enough dental wax to protect raw wound from arch bars or surgical wires • Consider using automatic teeth cleaner/irrigators (Waterpik®, Airfloss®) after one-week of surgery • Use interdental brushes • Powered toothbrush after one-week of surgery

• Brush or rinse/ gargle your mouth rigorously • Drink through straw as straw can lead to bleeding

• Try to get minimal physical exercise • Allow ample amount of rest to your body •

• Strenuous exercise, physical activity, brisk movements, driving vehicle for at least one month • Heavy machinery operation

• Immediately after surgery ✓ minimal movement such as attempting to open mouth ✓ Short walks, strength return activities are encouraged during hospital stay • One week after surgery ✓ Open and close your mouth more often ✓ Move jaw side to side and place one to two fingers in between front teeth • One month after surgery ✓ Place two to three fingers in between front teeth ✓ Move jaw freely ✓ Commence gentle exercise, climbing a flight of stairs

• Strenuous exercise, physical activity, brisk movements, driving vehicle for at least one month • Heavy machinery operation • Contact sports

• Strong positive mental attitude • Seek family/friends support • Performing meditation/yoga helps to relax your mind

• Unnecessary stress • Being negative • Skeptical in attitude

• Strong positive mental attitude • Seek family/friends support • Make an attempt to seek answers

• Unnecessary stress • Being negative • Skeptical in attitude

• Not following instructions

• Inform the clinic of unusual bleeding or tightness around the face even after one week • Use ice packs for the first 2-3 days • Sleep with head elevated and pillow propped • Intermittent moist heat could be used after 1-2 days post-surgery • Gentle massage could be commenced after 2-3 days to relieve muscle spasms

• • • •

• Follow all the instructions provided by your orthodontist and surgeon • Report of any breakage of brackets or wires and get it fixed • Follow the instructions provided by the anesthetic team

• Eat or drink previous night • Jewelry, make-up or any other items that hinder surgery • Tight fitting clothing'

General well-being and diet

• Get ample amount of rest • Take all the medications as prescribed and directed

• Biting on hard , crunchy, and chewy food (e.g., candies, popcorn, peanuts, meats) • alcoholic beverages, Smoking

Oral Hygiene

• Purchase a new soft bristle toothbrush • Rinse your mouth • Maintenance of oral hygiene • Professional cleaning

Physical activity or ambulatory care

Psychosocial response

Dos

Pain management/ wound Recovery /swelling • Report of any pain or discomfort • Follow instructions : coping skills

Fiddle with numbness Remove stiches Disturb clot Hot fermentation over the swelling

Fig. 11.1  Before and after surgery dos and don’ts

11.4 Conclusion Comprehensive pre- and post-surgery patient care checklist and patient instruction provide a prelude to high-quality predictable outcome. Patient care begins as soon as the patient seeks first consultation for jaw surgery and continues until the end of treatment. The orthodontist and surgeon must thoroughly evaluate every patient in order to optimize the clinical outcome.

References

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References 1. Akhtar A, MacFarlane RJ, Waseem M. Suppl 3: pre-operative assessment and post-operative care in elective shoulder surgery. Open Orthop J. 2013;7:316. 2. Garcia-Miguel F, Serrano-Aguilar P, Lopez-Bastida J.  Preoperative assessment. Lancet. 2003;362(9397):1749–57. 3. Arnold MJ, Beer J.  Preoperative evaluation: a time-saving algorithm: our preop evaluation method combines the latest guidelines and tools to help you avoid unnecessary testing and complete the process in one visit. J Fam Pract. 2016;65(10):702–10. 4. Kaplan EB, Sheiner LB, Boeckmann AJ, Roizen MF, Beal SL, Cohen SN, et al. The usefulness of preoperative laboratory screening. JAMA. 1985;253(24):3576–81. 5. Macario A, Roizen M, Thisted R, Kim S, Orkin F, Phelps C. Reassessment of preoperative laboratory testing has changed the test-ordering patterns of physicians. Surg Gynecol Obstet. 1992;175(6):539–47. 6. Velanovich V. The value of routine preoperative laboratory testing in predicting postoperative complications: a multivariate analysis. Surgery. 1991;109(3 Pt 1):236–43. 7. Al-Bitar ZB, Al-Ahmad HT. Anxiety and post-traumatic stress symptoms in orthognathic surgery patients. Eur J Orthod. 2016;39(1):92–7. 8. Bertolini F, Russo V, Sansebastiano G. Pre-and postsurgical psycho-emotional aspects of the orthognathic surgery patient. Int J Adult Orthodon Orthognath Surg. 2000;15(1):16–23. 9. Sarwer DB, Crerand CE.  Psychological issues in patient outcomes. Facial Plast Surg. 2002;18(02):125–34. 10. Carroll DH, Scahill L, Phillips KA.  Current concepts in body dysmorphic disorder. Arch Psychiatr Nurs. 2002;16(2):72–9. 11. Pavan C, Simonato P, Marini M, Mazzoleni F, Pavan L, Vindigni V.  Psychopathologic aspects of body dysmorphic disorder: a literature review. Aesthet Plast Surg. 2008;32(3):473–84. 12. Phillips KA.  Quality of life for patients with body dysmorphic disorder. J Nerv Ment Dis. 2000;188(3):170–5. 13. Looper KJ, Kirmayer LJ. Behavioral medicine approaches to somatoform disorders. J Consult Clin Psychol. 2002;70(3):810. 14. Mitchinson AR, Kim HM, Geisser M, Rosenberg JM, Hinshaw DB. Social connectedness and patient recovery after major operations. J Am Coll Surg. 2008;206(2):292–300. 15. Everhart JS, Best TM, Flanigan DC.  Psychological predictors of anterior cruciate liga ment reconstruction outcomes: a systematic review. Knee Surg Sports Traumatol Arthrosc. 2015;23(3):752–62. 16. Bhamrah G, Ahmad S, NiMhurchadha S.  Internet discussion forums, an informa tion and support resource for orthognathic patients. Am J Orthod Dentofac Orthop. 2015;147(1):89–96. 17. Kendell BD, Fonseca RJ, Lee M. Postoperative nutritional supplementation for the orthognathic surgery patient. J Oral Maxillofac Surg. 1982;40(4):205–13. 18. Worrall S. Changes in weight and body composition after orthognathic surgery and jaw fractures: a comparison of miniplates and intermaxillary fixation. Br J Oral Maxillofac Surg. 1994;32(5):289–92. 19. Anderson OA, Wearne IMJ. Informed consent for elective surgery—what is best practice? J R Soc Med. 2007;100(2):97–100. 20. Childers R, Lipsett PA, Pawlik TM.  Informed consent and the surgeon. J Am Coll Surg. 2009;208(4):627–34. 21. Thomas T, Robinson C, Champion D, McKell M, Pell M. Prediction and assessment of the severity of post-operative pain and of satisfaction with management. Pain. 1998;75(2–3):177–85. 22. Nagatsuka C, Ichinohe T, Kaneko Y.  Preemptive effects of a combination of preoperative diclofenac, butorphanol, and lidocaine on postoperative pain management following orthognathic surgery. Anesth Prog. 2000;47(4):119.

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23. Sato J, Goto J, Harahashi A, Murata T, Hata H, Yamazaki Y, et al. Oral health care reduces the risk of postoperative surgical site infection in inpatients with oral squamous cell carcinoma. Support Care Cancer. 2011;19(3):409–16. 24. Takai S, Kuriyama T, Yanagisawa M, Nakagawa K, Karasawa T. Incidence and bacteriology of bacteremia associated with various oral and maxillofacial surgical procedures. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2005;99(3):292–8. 25. Yoneyama T, Yoshida M, Matsui T, Sasaki H.  Oral care and pneumonia. Lancet. 1999;354(9177):515.

Potential Complications and Management of SFOA

12

If I had an hour to solve a problem I’d spend 55 minutes thinking about the problem and 5 minutes thinking about solutions. —Albert Einstein

12.1 Introduction Surgery-first orthodontic approach may pose potential complications ranging from minuscule errors to the most harrowing complex problems that not only cause significant damage to the hard and soft tissues but also require a remedial surgery. Complications that can occur at various stages of SFOA treatment will be discussed with regard to the planning and execution stages and also the adequate safety measures or resolution that could be implemented in order to counter the problems. A reference guide on how to deal with the perils posed to both orthodontist and surgeon whilst contemplating SFOA will be discussed in detail.

12.2 Orthodontist-Related Complications and Management 12.2.1 Pre-surgery Phase Complications arising from orthodontic mechanics are hardly encountered when carrying out SFOA in this phase as the minimal or no active orthodontic treatment carried out. So by that reason, practitioners of SFOA would face less complications in this phase as compared to using the conventional surgery approach. It is essential and important to assess the risks and potential complications that could be posed still and be amply equipped with tools that can assist in positive resolution for the effective and successful management of patient’s problems with SFOA. © Springer Nature Switzerland AG 2019 C. K. Chng et al., Surgery-First Orthodontic Management, https://doi.org/10.1007/978-3-030-18696-8_12

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These can be broadly described under the following categories: 1 . Etiological and clinical assessment. 2. SFOA planning (2D and 3D). 3. Orthodontic treatment execution. 4. Laboratory and splint fabrication.

12.2.1.1 Etiological and Clinical Assessment A thorough evaluation of maxillo-mandibular structures soft and hard tissues is essential as Xia et al. [1] reiterate the fact that jaw deformities occur as a result of either congenital or acquired etiological factors or a combination of both. This could arise from genetic abnormalities, deformations, intrauterine disruptions, infectious diseases, or abnormal functions that lead to various types of jaw deformities (size, position, orientation, shape, symmetry, and completeness) [2–4]. Failure to recognize this aforementioned critical aspect of patient assessment along with a lack of precise discernment of associated co-morbidities (e.g. chewing difficulty, sleep apnoea, dysarthria, psychological impedance) would lead to complications in the subsequent planning and execution. A checklist should be made comprising of skeletal, dental, soft tissue, and patient factors, and planning should be made in accordance to the ‘one patient two problem (skeletal and dental) concept’. Evaluation of psychosocial well-being with particular emphasis on body dysmorphic disorder (BDD) [5] in individuals seeking jaw surgery for the correction of physical defects is important, as Vulnik et al. in their study found that 10% screened positive for BDD and advised for (1) a psychiatric evaluation whenever a patient exhibits significant behavioural impairment and (2) to enforce a BDD screening questionnaire prior to SFOA [6, 7]. 12.2.1.2 SFOA Planning (2D and 3D) Advancements and refinements are occurring in the 3D assessment and planning arena of SFOA, but the application of face bow and articulator and other 2D modalities of image capture still remains the preferred approach for jaw surgery planning. Walker et al. emphasize that cases with facial asymmetry requiring the positioning of temporomandibular joints relative to the maxilla should consider using highly adjustable spirit level orthognathic face bow that allows more accurate records to be made of patients with asymmetrical maxilla instead of a semiadjustable articulator [8, 9]. In SFOA, since the malocclusion is still present, it is of the utmost importance to record the accurate position of the maxilla relative to the cranial base. This is especially important if a two-jaw surgery is planned. This will improve the accuracy of mounting of occlusal models on the articulator for the development of a more accurate prediction and surgical which will result in the most ideal surgical outcomes [10]. In 3D planning, orientation of the skull composite model cannot be overemphasized (for further reading on NHP, please refer to Chap. 4). Several techniques have been mentioned in the literature, such as 3D laser surface and digital gyroscope [11]. Further, complications encountered during the 3D planning (due to

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inherent errors in the hardware and software) could be resolved by exhaustive communication between the orthodontist and the surgeon and arriving at a clinically feasible treatment plan. Plooij et al. recommend that since 3D image and 3D fusion process are prone to errors, it is prudent to compare the 3D simulated model with clinical assessment and to rely on experience to assess if the predications are acceptable [12].

12.2.1.3 Orthodontic Treatment Execution The potential complications during orthodontic treatment execution could arise during bonding of brackets, placing wires, and surgical splint try-in. During bonding of brackets, the brackets are generally placed 1–6 weeks before the scheduled surgery, and passive ligature wires are used to secure the brackets in the event of a debond. During this phase, active orthodontic tooth movement is not desired, and, as such, no active wire should be used. Any tooth movements at this stage will prevent proper fitting of the surgical splint. It is prudent to use a passive ligation to avoid such a problem. The placing of stainless steel ligation wire along with K-hooks is preferred. On the day of surgical splint try-in, if the teeth have moved, the surgical splint can be trimmed and adjusted to accommodate for minor tooth movement. If tooth movement is significant, it will be best to repeat the procedure and fabricate a new surgical splint taking into account the new tooth positions. 12.2.1.4 Laboratory and Splint Fabrication 3D splint design and fabrication have the ability to visualize the anatomical structures in three dimension and confirm the planning in 6 degree of freedom making it highly precise. 3D printing material costs are steadily decreasing due to increase in supply and large-scale production. The complications that arise with splint design and fabrication and suitable resolution for the same are enumerated in Table 12.1.

12.2.2 Surgery Phase Frequent complications that can occur during surgery are (1) bracket debonding, (2) ligature wire breakage, (3) ill-fitting of surgical splints, and (4) inadvertent movement of teeth. Rebonding a bracket during surgery is impractical as it unnecessarily disrupts the surgery, and also the difficulty will be ensuring an uncontaminated dry field for bonding. Efforts must still be made to attempt to rebond the brackets as soon as possible. Post-surgery bonding is difficult, as well, as the patient has limited mouth opening and the patient is usually in quite a bit of discomfort at that point. One must take cognizance of the fact that a tooth or teeth without brackets will not move and will not be able to utilize the RAP effect post-surgery. Usage of moisture insensitive primer (MIP; Transbond; 3M Unitek, Monrovia, CA) could be used for bonding post-surgery to mitigate bonding issues. Ill-fitting or breakage of surgical splint is a possibility due to the use of poor-­ quality resin, and surgical splints become extremely thin due to over-trimming, which can affect the outcome even in the hands of the most skilled surgeon. Poor fit

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Table 12.1  Orthodontics-related complications, causes, and resolution Stage Pre-­surgery

Complication 1. Surgery planning is not accurate 2. Unable to establish two- or three-point contact in a transitional occlusion 3. Splint ill-fitting during try-in 4. Distorted splint

During surgery

1. Bracket debonding 2. Ligature wire breakage 3. Ill-fitting surgical wafer 4. Teeth not in position as planned

Causes 1. Stepwise cephalometry, face bow transfer, and model articulation are not in sync 2. (a) Creation of 3D composite image is not accurate   (b) Skeletal corrections are not defined accurately 3. (a) Not enough clearance between splint and the brackets causing rocking of splint    (b) Premature tooth movement leading to ill fit of the wafer 4. (a) Warping of splint. Ill fabrication or warping of stereolithographic models    (b) Poor-quality print material 1. (a) Inadvertent surgical instrument handling   (b) Incomplete/poor bonding 2. Ligation of bite wafer to the ligature wire 3. Not enough moisture is provided for the wafer resin 4. Use of arch wires for too long such that the teeth have moved

Resolution 1. Meticulous step-by-step procedure is important 2. (a) 3D composite images need to be accurately recorded, and judicious use of surgery planning software is important   (b) Skeletal discrepancies should be corrected by planning proper osteotomies; once the skeletal problem is corrected, every effort should be made to establish dental contact points to establish a orthodontically treatable occlusion 3. (a) Providing enough clearance between splint and bracket    (b) The use of passive ligature wires to avoid premature tooth movement 4. (a) Selection of better print material 1. (a) Delicate use of surgical instruments   (b) Thorough bonding procedure should be implemented 2. Use of K-hooks to ligate bite wafer to the bracket 3. Soak the wafer in water to avoid ill-fitting due to warping 4. Use of passive ligature wire, if need arises of using arch wires, use passive arch wires to avoid tooth movement (continued)

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Table 12.1 (continued) Stage Post-­surgery

Complication 1. Occlusion instability 2. Limited mouth opening 3. Decreased chewing efficiency 4. Excessive dryness of lips 5. Open bite   (a) Immediate   (b) Late 6. Dental damage    (a) Teeth broken or chipped off    (b) Pulp necrosis, root resorption   (c) Decalcification 7. Periodontal complications.   (a) Dehiscence   (b) Gingival recession or fenestration

Causes 1. Teeth are in transitional occlusion 2. Settling elastics and bite wafer restrains the mouth opening 3. Teeth are not in final occlusion 4. Lack of liquid diet 5. (a) Condyle displacement during fixation. Inadequate removal of bony interferences    (b) Collapse of transverse expansion. Failure to maintain the lateral expansion correction 7. (a) Mishandling of instruments    (b) Close proximity of interdental cut    (c) Poor oral hygiene 7. (a) Access incision too close to teeth    (b) Osteotomy cut too close or involving attached gingiva

Resolution 1. (a) Judicious use of settling elastics as enumerated in Chap. 5    (b) Use of chin cup for Class III patients    (c) Early removal of splint (within a week post-surgery)    (d) Use of TAD’s and cantilever mechanics for rapid correction of teeth utilizing RAP 2. Intermittent use of elastics is encouraged 3. Soft diet is preferred 4. Liquid diet is encouraged, and copious use of petroleum jelly is advised 5. (a) Ensure proper fit of the splint    (b) Minimize mobility   (c)Additional titanium plate fixation across segments 6. (a) Proper use of instruments    (b) Maintain a minimum of 2–3 mm interdental distance from the adjacent periodontal ligament space    (c) Early oral toileting is encouraged with professionally effective oral healthcare 7. (a) Avoid too close access incision    (b) Placement of osteotomy cut in movable gingiva    (c) A good access design with wide gingival cuff of more than 1 cm must be contemplated

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of the surgical splint could be due to the movement of the teeth or warpage of the resin, caution should be exercised to avoid any inadvertent tooth movement, and the surgical splint can be prevented warpage by dipping in sterile non-reactive liquid (e.g. water, betadine solution) to provide enough moisture.

12.2.3 Post-surgery Phase Some of the common challenges encountered during post-surgery are enumerated in Table 12.1. ‘Occlusal instability’ could be one of the most challenging entities encountered in SFOA. In order to minimize the instability of the transitional occlusion, one should initiate adjunctive orthodontic treatment as soon as possible postoperatively to transfigure the transitional occlusion into the solid final occlusion. The possible solutions to resolve transitional occlusion are detailed in Table 12.1.

12.3 Surgery-Related Complications and Management Although surgery-related complications are not in the scope of the book, some of the commonly encountered problems are mentioned in Table 12.2 and solutions also mentioned. Table 12.2  Surgery-related complications, causes, and resolution Complication Stage During 1. Haemorrhage surgery 2. Proximal segment fractures 3. Oro-antral communication 4. Trauma    (a) Gingiva and mucosa laceration and ulceration

Causes 1. Severance of major vessel 2. (a) Non-vigilant attention to surgical technique    (b) Overzealous use of surgical instrument    (c) Frail bony segments   (d) Third molar impacted 3. Poor access design with less considerations on the bony anatomy of the maxillary antrum 4. Surgical drill ill manipulation

Resolution 1. (a) Working meticulously with a thorough knowledge of major vessels course   (b) Cauterization   (c) Microvasculature reconstruction surgery    (d) Consider transfusion of red bold cells and fresh frozen plasma 2. (a) A thorough attention to surgical technique    (b) Proper use of surgical instruments    (c) Pre-treatment assessment of bone condition    (d) Removal of third molars at least 3–6 months before surgery to allow proper bone healing 3. Attempt for primary closure, try ribbon gauze soaked in whiteheads varnish, or bilateral palatal flap surgery 4.  Petroleum-based jelly or lip lubricants during the operation may prevent lip lesions and ulcerations (continued)

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Table 12.2 (continued) Complication Stage Post-­ 1. Infection surgery 2. Neurosensory disturbance 3. Vascular compromise/aseptic necrosis 4. Postoperative gingival recession 5. Extensive facial swelling 6. Delayed bony segments union 7. Unfavourable segmentalization/ fracture 8. TMJ resorption 9. Prolonged intense pain 10. Reduced nutrition

Causes 1. Poor oral hygiene, pre-existing conditions 2. Smoking or iatrogenic surgical factors resulting in compromised vascular flow 3. Inadvertent manipulation of soft tissues 4. (a) Condyle displacement during fixation Inadequate removal of bony interferences    (b) Collapse of transverse expansion. Failure to maintain the lateral expansion correction 5. Non-judicious use of surgical instruments 6. Extensive tissue manipulation 7. Incomplete interdental bony cuts/unfavourable fracture 8. Inadequate nutrition Fixation of the maxillary segments, the lack of consolidation over an extended period may cause pseudoarthrosis 9. Increase in force caused by the autorotation of the mandible 10. Dissatisfied patient could be a possibility

Resolution 1. Meticulous hygiene maintenance, rule out any pre-existing oral debilitations and treat appropriately, antibiotics therapy 2. Promotion of nerve regrowth medication (e.g. resveratrol) 3. Surgical debridement of necrotic areas, hyperbaric oxygen therapy 4. Appropriate dressing/packing of the wound 5. Minimize operation time, minimize tissue manipulation 6. Ensure complete bony cuts to avoid unpredictable propagation of osteotomy cuts 7. Re-intervention for proper segmentation fixation 8. For severe cases, condyle amputation and prosthetic substitution 9. Dissatisfied patients show worse pain symptoms, evaluate ‘body dysmorphic disorder’ 10. Adequate nutrition and caloric intake are vital

• enactment of a risk contingency plan

Implementing a comprehensive feed-back loop

• Develop further risk mitigation plans

• Persistent quality improvement

• Prioritizing risk and addressing the most pressing issue through collaboration

• involvement of specialty services (e.g managing body dysmorphic disorder) • Execution of specific actions

• Application of Immediate or delayed proactive risk intervention techniques and tools • ( eg reintervention jaw surgery, countering relapse tendency )

• Emphasize multidisciplinary team approach (eg Exhaustive t treatment plan exploring all possibilities of risk) • Enhancing risk monitoring behavior

•

Risk transference

Risk impact

Risk acceptance

Risk mitigation

Risk response

Risk assessment and characterization

Fig. 12.1  Risk management process for problems encountered in SFOA

• Integration of primary, secondary, and tertiary prevention methods (e.g. enforcement of oral hygiene habits, providing psychological motivation to the patient) • Anticipating risk and equipping to tackle

• implementation of preventative measures

Risk prevention

Establishing priorities

Risks identification

High Medium Low

142 12  Potential Complications and Management of SFOA

References

143

12.4 Conclusion The risk management process (Fig. 12.1) should be clearly understood by both the orthodontist and surgeon, and emphasis should be placed on the risk identification and assessment such that a suitable response could be formulated and executed for the prevention, mitigation, acceptance, and risk transference.

References 1. Xia J, Gateno J, Teichgraeber J, Yuan P, Li J, Chen K-C, et al. Algorithm for planning a double-­ jaw orthognathic surgery using a computer-aided surgical simulation (CASS) protocol. Part 2: three-dimensional cephalometry. Int J Oral Maxillofac Surg. 2015;44:1441–50. 2. Gateno J, Alfi D, Xia JJ, Teichgraeber JF. A geometric classification of jaw deformities. J Oral Maxillofac Surg. 2015;73:S26–31. 3. Gateno J, Xia JJ, Teichgraeber JF, Christensen AM, Lemoine JJ, Liebschner MA, et al. Clinical feasibility of computer-aided surgical simulation (CASS) in the treatment of complex cranio-­ maxillofacial deformities. J Oral Maxillofac Surg. 2007;65:728–34. 4. Xia JJ, Gateno J, Teichgraeber JF, Christensen AM, Lasky RE, Lemoine JJ, et al. Accuracy of the computer-aided surgical simulation (CASS) system in the treatment of patients with complex craniomaxillofacial deformity: a pilot study. J Oral Maxillofac Surg. 2007;65:248–54. 5. Rustemeyer J, Eke Z, Bremerich A. Perception of improvement after orthognathic surgery: the important variables affecting patient satisfaction. Oral Maxillofac Surg. 2010;14:155–62. 6. Vulink N, Rosenberg A, Plooij J, Koole R, Bergé S, Denys D.  Body dysmorphic disorder screening in maxillofacial outpatients presenting for orthognathic surgery. Int J Oral Maxillofac Surg. 2008;37:985–91. 7. Ishigooka J, Iwao M, Suzuki M, Fukuyama Y, Murasaki M, Miura S. Demographic features of patients seeking cosmetic surgery. Psychiatry Clin Neurosci. 1998;52:283–7. 8. Walker F, Ayoub AF, Moos KF, Barbenel J. Face bow and articulator for planning orthognathic surgery: 2 articulator. Br J Oral Maxillofac Surg. 2008;46:573–8. 9. Walker F, Ayoub AF, Moos KF, Barbenel J. Face bow and articulator for planning orthognathic surgery: 1 face bow. Br J Oral Maxillofac Surg. 2008;46:567–72. 10. Ellis E, Tharanon W, Gambrell K. Accuracy of face-bow transfer: effect on surgical prediction and postsurgical result. J Oral Maxillofac Surg. 1992;50:562–7. 11. Gateno J, Xia JJ, Teichgraeber JF, editors. New methods to evaluate craniofacial deformity and to plan surgical correction. Seminars in orthodontics. Amsterdam: Elsevier; 2011. 12. Plooij JM, Maal TJ, Haers P, Borstlap WA, Kuijpers-Jagtman AM, Bergé SJ. Digital three-­ dimensional image fusion processes for planning and evaluating orthodontics and orthognathic surgery. A systematic review. Int J Oral Maxillofac Surg. 2011;40:341–52.

Outcome Assessment of Surgery-First Orthognathic Approach

13

Research is to see what everybody else has seen, and to think what nobody else has thought. —Albert Szent-Gyorgyi

13.1 Introduction Various outcomes need to be assessed and proved feasible and efficient before a certain treatment modality is deemed as a viable modality to replace the conventional mode of treatment. In a treatment approach such as SFOA that involves at least two disciplines, one needs to ascertain certain outcomes such as clinical, psychological, and health resource utilization and compare this with the current modality of treatment for the evaluation of the true extent of feasibility and reliability (Fig. 13.1).

13.2 T  reatment Duration of SFOA Versus Conventional Orthognathic On an average, the total treatment duration for the conventional jaw surgery approach is 18–36 months, of which a major portion of time (about 17 months) is in the pre-surgical orthodontic phase [1, 2] (Table 13.1). Shortening the pre-surgical orthodontic treatment phase is the main emphasis of surgery-first orthognathic approach. The impact of SFOA on the pre-surgical orthodontics phase and its influence on the overall treatment will be discussed. In conventional jaw surgery, pre-­ surgical orthodontic phase is employed for some of the following reasons: (1) dental decompensation, (2) arch alignment, (3) maxilla-mandibular arch coordination, and (4) correction of curve of Spee, thus making the pre-surgical phase significantly longer. In SFOA, the pre-surgical phase of active orthodontic treatment is not © Springer Nature Switzerland AG 2019 C. K. Chng et al., Surgery-First Orthodontic Management, https://doi.org/10.1007/978-3-030-18696-8_13

145

Transverse Vertical Sagittal

TMJ stability /relapse

Muscles of mastication

Soft-tissue

Neurovascular

Mouth opening

Long-term outcome assessment

Single or double jaw surgery

Teeth inclination and angulation

Immediate/Short-term outcome Assessment

Occlusal stability

Dental

Fig. 13.1  Figure depicting the various scenarios of SFOA outcome assessment

Osteotomy stability /relapse

Skeletal

Clinical Outcome Assessments

Patient perception/motivation

Patient satisfaction/Bodyimage

Equipment: Softwares, navigation equipment, 3D printers

Manpower : planning, execution, lab procedures

Hospitalization/ ward

Morbidity/General Health QoL OHQoL

Health resource utilization

Psychological/Social Assessments

SFOA Outcome Assessment

146 13  Outcome Assessment of Surgery-First Orthognathic Approach

Study design Case-control retrospective

Case-control prospective

Case-control prospective

Author/year Park/2016 [3]

Huang/2016 [4]

Choi/2015 [5]

56 pts. (avg. age, 22.4 years): conventional jaw surgery (n, 24) and SFOA (n, 32)

Participant 40 pts.: 20 conventional jaw surgery (25.25 ± 3.77 years) and 20 SFOA (22.60 ± 5.39 years) 50 pts.: conventional jaw surgery (24.2 ± 5.8 years) and SFOA (25.2 ± 4.2 years)

Comparison Conventional surgery, bimaxillary surgery

Surgery-first approaches for patients with skeletal Class III dentofacial deformity

Conventional surgery

SFOA Class III Conventional malocclusion surgery, bimaxillary surgery

Intervention SFOA bimaxillary surgery

Method of measurement/outcome domain Cephalometric radiographs/skeletal and dental

(continued)

Conclusion No significant differences between the two groups in terms of the postoperative stability SFOA showed no Oral health-related Two questionnaires: quality of life and the Dental Impact on deterioration stage of quality of life Daily Living and satisfaction score which leads between surgery-­ 14-item Oral Health to better Impact profile first and satisfaction orthodontics-first compared to orthognathic orthodontics-first surgery patients group Surgery-first approach, SFOA is Reliability of a predictable and dental model. surgery-first applicable to treat Cephalometric orthognathic Class III approach without assessment (skeletal dentofacial and dental) pre-surgical deformities orthodontic treatment

Outcome primary/ secondary Postoperative stability/relapse rate

Table 13.1  Table describing some of the studies on SFOA’s stability, oral health-related quality of life (OHRQoL), and psychosocial well-being

13.2  Treatment Duration of SFOA Versus Conventional Orthognathic 147

Case-control retrospective

Retrospective cohort study

Ko/2011 [7]

Guo/2018 [8]

Symmetry group (n, 17; 22.9 ± 4.4 years) and asymmetry group (n, 12; 20.5 ± 2.2 years)

53 pts.: modified conventional jaw surgery (n, 35; 22.0 ± 4.1 years) and SFOA (n, 18; 24.6 ± 4.9 years)

Study design Participant Retrospective 55 pts.: conventional cohort study jaw surgery (n, 29; 22.2 ± 3.8 years) and SFOA (n, 26; 21.6 ± 3.3 years)

Author/year Wang/2018 [6]

Table 13.1 (continued)

Comparison Conventional surgery

Modified conventional surgery (MC)

SFOA mandibular prognathism without facial asymmetry

Intervention Bilateral sagittal split ramus osteotomy for mandibular prognathism using OFA

SFOA

SFOA mandibular prognathism with asymmetry

Outcome primary/ secondary Compare the postoperative changes of the condylar position after mandibular setback surgery using the orthodontics-first approach (OFA) and surgery-first approach (SFA) Post-surgical dental and skeletal stability and treatment efficacy of skeletal Class III malocclusion between 2 pre-surgical orthodontic managements Corrective outcomes and transverse stability after surgery-first surgical-­ orthodontic treatment in mandibular prognathism

Three-dimensional Corrected analysis. 3D facial CT outcomes showed good postoperative stability in both the symmetry and asymmetry groups

Method of measurement/outcome domain Conclusion Three-dimensional Regardless of the (3D) CT images timing of the operation (OFA vs SFA), the perioperative and postoperative changes of the condylar position after mandibular setback surgery are equivalent Lateral cephalograph No difference in SFOA and cephalometric conventional measurements surgery in amount of skeletal correction and post-surgical relapse, as well as treatment duration

148 13  Outcome Assessment of Surgery-First Orthognathic Approach

Retrospective cohort study

Liao/2018 [11]

N, 41, females. 24.0 ± 4.9 years

SFOA in skeletal Class III facial asymmetry

Conventional surgery

SFOA in skeletal Class III dentofacial deformities

Retrospective study

Jeong/2018 [10]

Conventional jaw surgery (n, 51; 23.1 years) and SFOA (n, 104; 23.3 years)

Comparison CPO In Class III malocclusion

Intervention MPO in Class III malocclusion

Author/year Study design Participant Joh/2013 [9] Retrospective 32 adult pts.: Minimal cohort study pre-surgical orthodontics (MPO) (n, 16) and conventional pre-surgical orthodontics (CPO) (n, 16)

Method of measurement/outcome domain Lateral cephalograph cephalometric measurements

(continued)

Conclusion No significant differences between the MPO and CPO groups in the hard and soft tissue cephalometric variables. MPO group had a shorter treatment time Lateral cephalograph SFOA can achieve Long-term similar long-term cephalometric outcomes of vertical stability measurements vertical skeletal results to the stability conventional surgery Determine whether Photographs and study SFOA improves facial asymmetry the SFOA and the models using the described guidelines for guidelines setups of the models could be used to improve facial symmetry with bimaxillary surgery

Outcome primary/ secondary Changes in the hard and soft tissues and the treatment efficacy of two-jaw surgery

13.2  Treatment Duration of SFOA Versus Conventional Orthognathic 149

Retrospective cohort study

Prospective study

Retrospective 26 pts., conventional study jaw surgery (n, 15; 25.0 ± 3.2 years) and SFOA (n, 11; 26.2 ± 4.4 years)

Zhou/2016 [13]

Feu/2017 [14]

Park/2015 [15]

16 pts., conventional jaw surgery (n, 8; 26.8 ± 7.1 years) and SFOA (n, 8; 22.9 ± 5.4 years)

40 pts., conventional jaw surgery (n, 20; 23.1 years) and SFOA (n, 20; 20.9 ± 2.1 years)

Study design Participant Retrospective N, 35 pts.; 24.7 years study

Author/year Choi/2015 [12]

Table 13.1 (continued)

Conventional surgery

Conventional surgery

SFOA in skeletal Class III dentofacial deformities

SFOA in skeletal Class III dentofacial deformities

Intervention Comparison SFOA clockwise maxillo-­ mandibular complex (MMC) skeletal Class III deformities Conventional SFOA in surgery skeletal Class III dentofacial deformities

Method of measurement/outcome domain Lateral cephalograph cephalometric measurements

Oral health-related quality of life (OHRQoL), quality of the orthodontic outcome, and average treatment duration Compare the quality of life (QoL)

Orthognathic QoL Questionnaire (OQLQ)

Orthognathic Quality of Life Questionnaire (OQLQ) and the Oral Health Impact Profile-short version (OHIP-14)

Compare treatment Lateral cephalograph cephalometric efficacy and measurements post-surgical stability

Outcome primary/ secondary Posterior pharyngeal airway change

SFA might have an advantage over CTM group in terms of no deterioration stage of OQLQ score

SFOA and conventional surgery showed similar extents and directions of skeletal changes in patients with Class III malocclusion OHRQoL improved significantly in SFOA

Conclusion SFOA MMC did not cause severe posterior airway space changes

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Participant 33 pts., conventional jaw surgery (n, 25; 25.0 ± 5.5 years) and SFOA (n, 8; 35.6 ± 13.4 years)

9 pts. (26.7 years)

Author/year Study design Brucoli/2018 Prospective [16] study

Zingler/2017 Prospective [17] cohort study

SFOA in skeletal Class III and Class II dentofacial deformities

Intervention SFOA in skeletal Class III dentofacial deformities

Pre-treatment baseline

Comparison Conventional surgery

Method of measurement/outcome domain Oral Health Impact Profile questionnaire, Temperament and Character Inventory (TCI), Resilience Scale for Adults (RSA), Italian Validation of the Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ), Beck Depression Inventory second edition (BDIII), the Rosenberg Self-­Esteem Scale (RSES) Psychological and Orthognathic quality biological changes of life (OQLQ) questionnaire, Sense in SFOA of Coherence 29-item scale (SOC-29), and longitudinal day-to-­ day questionnaire IL-1 b, IL-6, TGF b 1–3, MMP-2, and VEGF were assessed in crevicular fluid by bead-based multiplex assays Outcome primary/ secondary Psychosocial well-being, self-esteem, anxiety, and quality of life

(continued)

SFOA has positive impact on patient’s psychosocial status. SFOA elevated levels of bone remodelling factors

Conclusion SFOA positively influence the compliance and psychological status of the patients

13.2  Treatment Duration of SFOA Versus Conventional Orthognathic 151

Retrospective 37 pts., conventional cohort study jaw surgery (n, 17; 20.8 ± 0.9 years) and SFOA (n, 20; 21.1 ± 0.7 years)

Choi/2016 [21]

61 pts., conventional jaw surgery (n, 38; 21.6 ± 3.5 years) and SFOA (n, 23; 23.0 ± 6.3 years)

Retrospective cohort study

Kim/2014 [20]

Ko/2013 [19]

Participant 50 pts., conventional jaw surgery (n, 25; 25.1 ± 6.8 years) and SFOA (n, 25; 25.4 ± 6.4 years) Retrospective 45 pts., conventional cohort study jaw surgery (n, 25; 25.1 ± 6.8 years) and SFOA (n, 25; 25.4 ± 6.4 years)

Study design Longitudinal prospective cohort study

Author/year Wang/2017 [18]

Table 13.1 (continued)

Lateral cephalograph Identify the parameters related cephalometric to skeletal stability measurements after SFOA

Lateral cephalograph cephalometric measurements

Stability of mandibular setback surgery

Lateral cephalograph Postoperative skeletal and dental cephalometric measurements changes

Comparison Conventional surgery

Groups based on the amount of horizontal relapse

Conventional surgery

Conventional surgery using IVRO

Intervention SFOA in skeletal Class III dentofacial deformities SFOA in skeletal Class III dentofacial deformities

SFOA in skeletal Class III dentofacial deformities SFOA in skeletal Class III dentofacial deformities using intra-oral vertical ramus osteotomy (IVRO)

Method of measurement/outcome domain Oral health-related quality of life (OHRQoL) questionnaire

Outcome primary/ secondary Oral health-related quality of life

Factors for SFOA instability are larger overbite, a deeper curve of Spee, a greater negative overjet, and a greater mandibular setback Mandibular sagittal split ramus osteotomy in SFOA is less stable than conventional surgery IVRO in SFOA shows linear correlation with mandibular setback and vertical movement of mandible

Conclusion Both treatment methods can obtain the same results

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Retrospective study

Liao/2010 [23]

33 pts., conventional jaw surgery (n, 13; 21.0 ± 4.0 years) and SFOA (n, 20; 23.0 ± 4.0 years)

Study design Participant Retrospective 11 pts.; cohort study 22.9 ± 2.5 years

Author/year Baek/2010 [22]

Comparison Pre-treatment baseline

Conventional surgery in skeletal Class III open bite

Intervention SFOA in skeletal Class III dentofacial deformities

SFOA in skeletal Class III open bite

Method of measurement/outcome domain Lateral cephalograph cephalometric measurements

Evaluate treatment Lateral cephalograph, outcome in terms Peer Assessment of facial aesthetics, Rating occlusion, stability, and efficiency

Outcome primary/ secondary Evaluate the surgical movement and postoperative orthodontic treatment

Conclusion The mandible seems to relapse forward immediately after wafer removal and before labioversion of the lower incisors Patients receiving pre-surgical orthodontics undergo longer treatment time than those receiving no pre-surgical orthodontic

13.2  Treatment Duration of SFOA Versus Conventional Orthognathic 153

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performed, minimizing the time required. The ‘model surgery’ is employed to preview the post-surgery occlusion in SFOA.  Two scenarios are worth mentioning whilst estimating the amount of time that will be taken by orthodontic treatment post-surgery when previewing the transitional occlusion on a model surgery.

13.2.1 Orthodontic Treatment Difficulty Level: Minimal to Moderate If the model surgery is able to show that the tooth movement that shall be commenced post-surgery is well within the realms of conventional orthodontic tooth movement, then the overall treatment time could be significantly reduced. The reduction in time comes in part from utilizing the RAP effect post-surgically. Smart planning of the surgery could also rely on surgical movements to assist in some orthodontic correction.

13.2.2 Orthodontic Treatment Difficulty Level: Severe If the model surgery shows some of the below-mentioned scenarios (and not limited to), then the SFOA approach may not significantly reduce the overall treatment time as the following scenarios may take beyond the 4–5 months of RAP period to complete the post-orthodontics movement. • More than one cusp width posterior crossbite. • Large overbite with anterior teeth inclination that need extensive orthodontic mechanotherapy post-surgery. • Severe crowding or malocclusion requiring teeth extraction. • Musculoskeletal aberrations precluding orthodontic tooth movement. But the question is, can the pre-surgical phase be eliminated in all the SFOA cases, thereby reducing the total treatment time? Woo et al. conducted a study to investigate actual time taken by SFOA Class III cases and compared with conventional jaw surgery cases and reported that the SFOA for jaw surgery can accelerate orthodontic treatment and reduce the total duration of treatment needed to correct dentofacial deformities when tooth extraction is not needed, and the total treatment time may be associated with many factors including host factors (extent of severity in three dimensions) and surgical factors (surgeons skill, fixation methods, and muscle response). They further inferred that, regardless of surgery approach, once the teeth extraction is planned, the tooth mobilization may occur for some time (considering the RAP period); nonetheless, once the RAP period subsides, the tooth movement would follow its own regular course. Liao et al. conducted a study to evaluate the effect of pre-surgical and no pre-surgical orthodontics on the treatment outcome in terms of facial aesthetics, occlusion, stability, and efficiency in skeletal Class III open bite cases. One key finding of this study was a significant overall reduction in

13.4  Quality of Life Outcomes and Psychological Status for SFOA

155

treatment time in the no pre-surgical orthodontics group in comparison to pre-­ surgical orthodontics group. They concluded that the resulting decrease in time could be due to the following reasons: (1) skeleton and soft tissue surrounding the teeth are brought back to normalcy, thus allowing the swift orthodontic tooth movement in a relatively anatomically normal contiguity; (2) orthodontic tooth movement increases when the teeth are in non-occlusion (i.e. unlocking occlusion) removing occlusal interferences, thus enhancing expediency of alignment of teeth, arch levelling, and coordination; and (3) increased bone turnover post-surgery (RAP) augmenting orthodontic tooth movement.

13.3 Stability of SFOA Versus Conventional Jaw Surgery In the Liao et al. study, they showed good stability in horizontal directions (at pogonion) with mild rate of relapse in both SFOA and conventional jaw surgery groups. However, vertical mandibular stability worsened in the non-pre-surgical orthodontics group, but the direction of instability was favourable for open bite correction in the skeletal Class III patients that were studied [23]. Ko et al. reported minimal differences in stability between conventional jaw surgery and SFOA; after conducting further research on the correlation between surgery-first orthognathic approach and relapse factors, they also reported that setback, overbite, overjet, and curve of Spee were closely related to the relapse rate and concluded that the initial overbite may be an indicator in predicting possible skeletal relapse of mandibular setback surgery in SFOA [19]. Wang et  al. conducted a retrospective cohort study to evaluate the positional changes of the condyle after mandibular setback surgery in SFOA and conventional jaw surgery approach. Their computed tomography study measured the bodily shift of the condylar centre, and rotational movement of the condylar head of preoperative, postoperative, and at 6-month follow-up images concluded that there was no significant difference regardless of the timing of the operation to the changes of the condylar position after mandibular setback surgery [6]. Guo et al. conducted a study to evaluate the corrective outcome and transverse stability in Class III facial asymmetry and observed good stability postoperatively in both the symmetry and asymmetry groups [8]. Most of the outcome assessment studies are conducted on skeletal Class III individuals and have been reported that the relapse associated with SFOA is similar to conventional jaw surgery [3, 8, 24, 25, 26]. However, there is little evidence on the benefits, if any, for skeletal Class II malocclusion. Further research can be done on this area.

13.4 Quality of Life Outcomes and Psychological Status for SFOA Several studies have dealt with the quality of life (QoL) of conventional jaw surgery that typically involves a pre-surgical orthodontic phase and concluded that, although, the overall patient experience in terms of treatment outcome, social relationship,

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facial aesthetics, and oral function had improved post-treatment; the long course of treatment, worsening of the facial profile especially during pre-surgical orthodontics phase, and functional unease such as masticatory discomfort affected the QoL negatively [27–33]. Studies have shown that oral health-related quality of life (OHRQoL) is worse in pre-surgical orthodontics phase than in the post-surgical orthodontic phase [32, 33]. These aforementioned reasons as a result of conventional jaw surgery, especially the pre-surgical orthodontics phase, is one of the main reasons for SFOA’s emergence. Several tests and questionnaires have been implemented to assess the patients’ psychological status and quality of life outcomes. Some of the commonly used ones are (1) Orthognathic QoL Questionnaire (OQLQ), (2) oral health-related quality of life (OHRQoL), (3) Resilience Scale for Adults (RSA), (4) Psychological Impact of Dental Aesthetics Questionnaire (PIDAQ), (5) Beck Depression Inventory second edition (BDIII), (6) Rosenberg Self-Esteem Scale (RSES), (7) oral health status questionnaire (OHSQ), and the 14-item (8) Oral Health Impact Profile (OHIP-14). Huang et al. evaluated the changes of oral health-related quality of life (OHRQoL) and satisfaction between SFOA and conventional jaw surgery and reported that OHRQoL is significantly improved in SFOA. The study evaluated functional limitation, physical pain, psychological discomfort, physical disability, psychological disability, social disability, and any handicaps using Dental Impact on Daily Living (DIDL) questionnaire and reported that [34] SFOA could improve OHRQoL immediately and lead to better satisfaction in the quality of life survey in comparison to conventional jaw surgery group.

13.5 SFOA: Evidence-Based Practice Four systematic and one meta-analysis were conducted to evaluate the current evidence on postoperative stability, efficacy, and surgical results between SFOA and conventional jaw surgery (Table  13.2) [35–38]. The studies were performed in accord with recommendations from the Cochrane Collaboration, Quality of Reporting of Meta-analyses (QUOROM) guidelines, PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses), and PICOS (participants, intervention, comparisons, outcomes, and study design). Electronic searches were made on PubMed, Embase, and Cochrane Database with Medical Subject Headings (MeSH) search headings were used surgery first, surgery early, and orthognathic surgery. Yang et al. concluded that SFOA offers an efficient alternative to conventional jaw surgery with shorter treatment duration, with comparable postoperative stability. However, SFOA had a longer duration in the post-surgical orthodontic phase when compared to conventional jaw surgery [35]. Peiro-Guijarro et al. and Huang et al. noted that SFOA is a new treatment approach which is poised to be established as a new treatment paradigm for the management of dentomaxillofacial deformity with studies showing satisfactory outcomes and high acceptance rate amongst the patients. They deduced that the results should be interpreted with

13.6 Conclusion

157

Table 13.2  Table showing important systematic review, meta-analysis, and randomized controlled trials on SFOA First author Le Yang [35]

Hongpu Wei [36]

Huang CS [37]

Peiro-­ Guijarro [38]

Year Study type Purpose of study 2017 SR∗ & MAǂ Does the surgery-first approach produce better outcomes in orthognathic surgery? 2018 SR & MA Compare the difference in postoperative stability between a SFOA and a conventional orthodonticsfirst approach (COA) 2014 SR Appraise the currently available evidence on the surgery-first approach and support its use in orthognathic surgery 2015 SR Analyse current protocols and results of patients treated with surgery first and compare the outcomes with a conventional approach

Outcome SFOA significantly shortens total treatment time, with comparable postoperative stability SFOA mandible tends to rotate counterclockwise more than COA, indicating poor post-op stability in SFOA than COA Both the surgery-first approach and orthodontics-first approach had similar long-term outcomes in dentofacial relationship Reduce total treatment time significantly and achieve high levels of patient and orthodontist satisfaction. Lack of prospective long-term follow-up

SR Systematic review, ǂMA Meta-analysis

*

caution because of the wide variance of study designs and outcome variables, reporting biases, and lack of prospective long-term follow-ups [37, 38]. On the contrary, Wei et al. suggested that SFOA might yield poorer results especially with the mandible rotated in a counterclockwise direction leading to worsen relapse rate. They also noted that their finding largely relies on the currently available data which might have potential bias as the studies that their meta-analysis included were either two-­dimensional assessment studies using lateral cephalometric radiographs. Some of these studies are retrospective with selection bias. Credible evidence needs to be gathered in the field of health resource utilization of SFOA (in terms of hospitalization/ward; manpower, planning, execution, lab procedures; and equipment; softwares, navigation, and 3D printers).

13.6 Conclusion SFOA as a new treatment philosophy is experiencing a state of evolution, and it is at the foothills warming up itself before the final ascension—as Thomas Kuhn in his philosophical book The Structure of Scientific Revolutions remarks that that every single scientific field experiences a periodic, non-linear, revolutionary accrual of information referred to as ‘paradigm shifts’, and often the ‘alternate concepts’ (in this case, SFOA) are looked upon with initial contempt and scepticism, but as superfluous favourable evidence is gathered, the ‘alternative concepts’ garner widespread ‘peer-group’ consensus and is bestowed its due credibility, dismissing the initial disregard [39].

158

13  Outcome Assessment of Surgery-First Orthognathic Approach

References 1. Centenero SA-H, Hernández-Alfaro F. 3D planning in orthognathic surgery: CAD/CAM surgical splints and prediction of the soft and hard tissues results–our experience in 16 cases. J Cranio-Maxillofac Surg. 2012;40:162–8. 2. Woo SJ, Jong WC, Do YK, Jang YL, Soon MK.  Can a surgery-first orthognathic approach reduce the total treatment time? Int J Oral Maxillofac Surg. 2017;46:473–82. 3. Park K-H, Sandor G, Kim Y-D. Skeletal stability of surgery-first bimaxillary orthognathic surgery for skeletal class III malocclusion, using standardized criteria. Int J Oral Maxillofac Surg. 2016;45:35–40. 4. Huang S, Chen W, Ni Z, Zhou Y. The changes of oral health-related quality of life and satisfaction after surgery-first orthognathic approach: a longitudinal prospective study. Head Face Med. 2016;12:2. 5. Choi JW, Lee JY, Yang SJ, Koh KS. The reliability of a surgery-first orthognathic approach without presurgical orthodontic treatment for skeletal class III dentofacial deformity. Ann Plast Surg. 2015;74:333–41. 6. Wang T, Han JJ, Oh H-K, Park H-J, Jung S, Kook M-S. Comparison of orthodontics-first and surgery-first approach in positional changes of the condyle after mandibular setback surgery using three-dimensional analysis. J Oral Maxillofac Surg. 2016;74:2487–96. 7. Ko EW-C, Hsu SS-P, Hsieh H-Y, Wang Y-C, Huang CS, Chen YR. Comparison of progressive cephalometric changes and postsurgical stability of skeletal Class III correction with and without presurgical orthodontic treatment. J Oral Maxillofac Surg. 2011;69:1469–77. 8. Guo J, Wang T, Han JJ, Jung S, Kook M-S, Park H-J, et al. Corrective outcome and transverse stability after orthognathic surgery using a surgery-first approach in mandibular prognathism with and without facial asymmetry. Oral Surg Oral Med Oral Pathol Oral Radiol. 2018. 9. Joh B, Bayome M, Park JH, Park JU, Kim Y, Kook Y-A. Evaluation of minimal versus conventional presurgical orthodontics in skeletal class III patients treated with two-jaw surgery. J Oral Maxillofac Surg. 2013;71:1733–41. 10. Jeong WS, Lee JY, Choi JW.  Large-scale study of long-term vertical skeletal stability in a surgery-­ first orthognathic approach without presurgical orthodontic treatment: part II.  J Craniofac Surg. 2018;29:953–8. 11. Liao Y-F, Chen Y-F, Yao C-F, Chen Y-A, Chen Y-R. Long-term outcomes of bimaxillary surgery for treatment of asymmetric skeletal class III deformity using surgery-first approach. Clin Oral Investig. 2019;23:1–9. 12. Choi JW, Park YJ, Lee C-Y. Posterior pharyngeal airway in clockwise rotation of maxillomandibular complex using surgery-first orthognathic approach. Plast Reconstr Surg Glob Open. 2015;3:e485. 13. Zhou Y, Li Z, Wang X, Zou B, Zhou Y. Progressive changes in patients with skeletal class III malocclusion treated by 2-jaw surgery with minimal and conventional presurgical orthodontics: a comparative study. Am J Orthod Dentofac Orthop. 2016;149:244–52. 14. Feu D, de Oliveira BH, Palomares NB, Celeste RK, Miguel JAM. Oral health-related quality of life changes in patients with severe Class III malocclusion treated with the 2-jaw surgery-­ first approach. Am J Orthod Dentofac Orthop. 2017;151:1048–57. 15. Park J-K, Choi J-Y, Yang I-H, Baek S-H. Patient’s satisfaction in skeletal class III cases treated with two-jaw surgery using orthognathic quality of life questionnaire: conventional three-stage method versus surgery-first approach. J Craniofac Surg. 2015;26:2086–93. 16. Brucoli M, Zeppegno P, Benech R, Boffano P, Benech A. Psychodynamic features associated with orthognathic surgery: a comparison between conventional orthognathic treatment and “surgery first” approach. J Oral Maxillofac Surg. 2019;77(1):157–63. 17. Zingler S, Hakim E, Finke D, Brunner M, Saure D, Hoffmann J, et al. Surgery-first approach in orthognathic surgery: Psychological and biological aspects—a prospective cohort study. J Cranio-Maxillofac Surg. 2017;45:1293–301. 18. Wang J, Chen W, Ni Z, Zheng M, Liang X, Zheng Y, et al. Timing of orthognathic surgery on the changes of oral health-related quality of life in Chinese orthognathic surgery patients. Am J Orthod Dentofac Orthop. 2017;151:565–71.

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19. Ko EW-C, Lin SC, Chen YR, Huang CS. Skeletal and dental variables related to the stability of orthognathic surgery in skeletal Class III malocclusion with a surgery-first approach. J Oral Maxillofac Surg. 2013;71:e215–e23. 20. Kim C-S, Lee S-C, Kyung H-M, Park H-S, Kwon T-G. Stability of mandibular setback surgery with and without presurgical orthodontics. J Oral Maxillofac Surg. 2014;72:779–87. 21. Choi S-H, Hwang C-J, Baik H-S, Jung Y-S, Lee K-J. Stability of pre-orthodontic orthognathic surgery using intraoral vertical ramus osteotomy versus conventional treatment. J Oral Maxillofac Surg. 2016;74:610–9. 22. Baek S-H, Ahn H-W, Kwon Y-H, Choi J-Y. Surgery-first approach in skeletal class III malocclusion treated with 2-jaw surgery: evaluation of surgical movement and postoperative orthodontic treatment. J Craniofac Surg. 2010;21:332–8. 23. Liao Y-F, Chiu Y-T, Huang C-S, Ko EW-C, Chen Y-R. Presurgical orthodontics versus no presurgical orthodontics: treatment outcome of surgical-orthodontic correction for skeletal class III open bite. Plast Reconstr Surg. 2010;126:2074–83. 24. Gander T, Bredell M, Eliades T, Rücker M, Essig HJJC-MS.  Splintless orthognathic surgery: a novel technique using patient-specific implants (PSI). J Craniomaxillofac Surg. 2015;43:319–22. 25. Holzinger D, Juergens P, Shahim K, Reyes M, Schicho K, Millesi G, et al. Accuracy of soft tissue prediction in surgery-first treatment concept in orthognathic surgery: a prospective study. J Cranio-Maxillofac Surg. 2018;46(9):1455–60. 26. Park H-M, Lee Y-K, Choi J-Y, Baek S-H. Maxillary incisor inclination of skeletal Class III patients treated with extraction of the upper first premolars and two-jaw surgery: conventional orthognathic surgery vs surgery-first approach. Angle Orthod. 2013;84:720–9. 27. Lee S, McGrath C, Samman N. Quality of life in patients with dentofacial deformity: a comparison of measurement approaches. Int J Oral Maxillofac Surg. 2007;36:488–92. PubMed PMID: 17339101. Epub 2007/03/07. 28. Bock JJ, Odemar F, Fuhrmann RA.  Assessment of quality of life in patients undergoing orthognathic surgery. J Orofac Orthop. 2009;70:407. 29. Rivera SM, Hatch JP, Rugh JD, editors. Psychosocial factors associated with orthodontic and orthognathic surgical treatment. Seminars in orthodontics. Amsterdam: Elsevier; 2000. 30. Motegi E, Hatch JP, Rugh JD, Yamaguchi H. Health-related quality of life and psychosocial function 5 years after orthognathic surgery. Am J Orthod Dentofac Orthop. 2003;124:138–43. 31. Modig M, Andersson L, Wårdh I. Patients’ perception of improvement after orthognathic surgery: pilot study. Br J Oral Maxillofac Surg. 2006;44:24–7. 32. Esperão PTG, de Oliveira BH, de Oliveira Almeida MA, Kiyak HA, Miguel JAM.  Oral health-related quality of life in orthognathic surgery patients. Am J Orthod Dentofac Orthop. 2010;137:790–5. 33. Palomares NB, Celeste RK, Miguel JAM. Impact of orthosurgical treatment phases on oral health–related quality of life. Am J Orthod Dentofac Orthop. 2016;149:171–81. 34. Bobek SL.  Applications of navigation for orthognathic surgery. Oral Maxillofac Surg Clin North Am. 2014;26:587–98. 35. Yang L, Y-d X, Y-j L, Wang X, Li J-y, G-q L. Does the surgery-first approach produce better outcomes in orthognathic surgery? A systematic review and meta-analysis. J Oral Maxillofac Surg. 2017;75:2422–9. 36. Wei H, Liu Z, Zang J, Wang X. Surgery first/early orthognathic approach may yield poorer postsurgical stability than conventional orthodontics first approach: a systematic review and meta-analysis. Oral Surg Oral Med Oral Pathol Oral Radiol. 2018;126(2):107–16. 37. Huang C, Hsu S, Chen Y-R. Systematic review of the surgery-first approach in orthognathic surgery. Biom J. 2014;37:184. 38. Peiró-Guijarro MA, Guijarro-Martínez R, Hernández-Alfaro F. Surgery first in orthognathic surgery: a systematic review of the literature. Am J Orthod Dentofac Orthop. 2016;149:448–62. 39. Kuhn TS, Hawkins D. The structure of scientific revolutions. Am J Phys. 1963;31:554–5.

Future of Surgery-First Orthognathic Approach

14

I never think of the future- it comes soon enough. —Albert Einstein

14.1 Introduction Future of SFOA is based on the rapid developments in the three-dimensional imaging technology aiding diagnosis and management of jaw surgery [1–3]. The improved application of computer-aided design (CAD) and computer-aided manufacturing (CAM), in particular, rapid prototyping (RP), has made the fabrication of the surgical splints a reality. 3D imaging coupled with 3D imaging analysis software and CAD/CAM technology has seamlessly transformed fabrication of surgical splints from a labour-intensive laboratory procedure to an easy, reliable, and quick chair-side clinical affair [4–7]. For ease of understanding the integration of technology in the diagnosis and management of jaw surgery, it will be divided into the following parts (Fig. 14.1): • • • • •

3D surface photomapping and soft tissue simulation. Virtual surgical planning (VSP). ‘Tools of transfer’ for surgery planning. 3D printing/rapid prototyping. Augmented real-time and virtual surgical navigation.

14.2 3D Image Acquisition and Diagnosis Recently, 3D imaging has found an enormous growth and refinement in the field of medical computed tomography (CT) imaging. Cone beam computed tomography (CBCT) has gained popularity in terms of acquiring volumetric data as it allows © Springer Nature Switzerland AG 2019 C. K. Chng et al., Surgery-First Orthodontic Management, https://doi.org/10.1007/978-3-030-18696-8_14

161

162

14  Future of Surgery-First Orthognathic Approach

3D photos 3dMD face system (3dMD Inc.)

3D printer Steriolithography

CBCT Scan + Trios 3 Shape Scan

Creation of ‘Composite Model’ (3D Soft tissue+ 3D Dentition+ 3D Skeleton)

Virtual Surgical Splint /surgical cutting guides construction

Virtual Surgical Planning Software

3D printed splint + 3D Surgical Navigation

Fig. 14.1  Flow chart explaining the 3D image acquisition, creation of composite model, and execution of surgery plan for the creation of 3D-printed surgical splints and 3D surgical navigation

precise 3D reconstruction with reduced radiation dosage with a short scanning time and at an affordable cost [8, 9]. Surface data capture technology has also evolved [10]. Non-contact surface scanning like 3D laser scanners (Konica Minolta Vivid 910, Tokyo, Japan) and 3D photogrammetry (3dMD Face System, 3dMD Inc., Atlanta, GA, USA) are some of the surface image acquiring technologies that allow the surface data acquisition of the soft tissue using high-speed and high-resolution data capturing algorithms. 3D laser scanners and synchronized multi-cameras of 3D photogrammetry not only integrate the missing link (i.e. soft tissue) of CBCT but also enable the end user to better simulate the soft tissue responses to osseous movements during virtual surgical planning [11, 12] (Table 14.1). The current soft tissue capturing modalities rely on computing algorithms for soft tissue simulations, such as the mass spring model, the finite-element model, and the mass tensor model with a high level of prediction accuracy (100% for upper lip, 98% for lower lip, etc.) [13, 14]. Furthermore, there is the ability for the integration of hard tissue scan and soft tissue surface images which can be superimposed three-dimensionally. The 3D superimposition of dental arches is recommended as the CT images might show ‘metal streak artefact’ in the teeth area, due to orthodontic brackets or metallic restoration, and prosthodontic work (prosthodontics crowns, implants, etc.). To minimize or eliminate the metal streak artefact, it is essential to replace the distorted CT images such that a clear region is obtained for efficient viewing, planning, and production of accurate surgical splints. Although newer CBCT machines have an

Dolphin 3D Surgery (v11.8)

Invivo5

Proplan CMF

Osirix (v8.0.2)

VSP® Orthognathics

2

3

4

5

6

Sr. No. Software name 1 NemoFAB 3D

3D Systems

Pixmeo SARL

Materialise

Anatomage

Dolphin Imaging & Management Solutions

Company Software Nemotec S.L.

Highlight • Surgery simulation and able to predict postoperative outcomes • Produce CAD/CAM surgical splints to avoid errors in the traditional model process • Ability to merge a CBCT volume scan, digital study model, and face photo to perform a 3D virtual surgery workup • Digital study model software allows seamless integration with CEREC Ortho software • Automatic volume reconstruction • High-quality 3D rendering • Airway analysis • Plan for orthognathic procedures and soft tissue simulations • Able to create 3D anatomical models and surgical guides • Most widely used medical viewer in the world (35% growth in 2016) • Currently only supported on Apple Mac OS • Complete virtual planning service that eliminates the need for traditional model surgery • Partnered with Dolphin Imaging for surgical planning

Table 14.1  Recent advances in jaw surgery management software

No

Free

http://www.materialise.com/en/medical/ software/proplan-cmf http://www.osirix-viewer.com

(continued)

No

No

http://www.anatomage.com/invivo5

http://www.medicalmodeling.com/solutionsfor-surgeons/vsp-technology/ vsp-orthognathics/

No

Free to use? No

http://www.dolphinimaging.com/product/ ThreeD#3D_Surgery

Website http://nemotecstore.com/product/ nemoceph-fab-3d/

14.2  3D Image Acquisition and Diagnosis 163

Planmeca Romexis®

CS 3D Imaging Software

3D Slicer (v4.6)

Image J

ITK-SNAP (v3.6.0)

iPlan CMF

8

9

10

11

12

13

Brainlab

ITK-SNAP

ImageJ developers

Kitware Inc.

Carestream dental

Planmeca

Sr. Company No. Software name 7 Tx STUDIO™ (v5.4) i-CAT

Table 14.1 (continued) Highlight • Conveniently order surgical guides through the Tx STUDIO software • Automatic nerve canal tracing • Best compatibility with other systems • Mobile app allows viewing of 2D and 3D images on mobile phone • Comprehensive assessment of dental and skeletal landmarks • Design custom appliances and image-­ guided treatment • Open-source software platform available on Linux, Mac OS X, and Windows • Multimodality imaging includes MRI, CT, US, and microscopy • No restriction on use as it is intended for research • Java-based open-source software— compatible on all major platforms • World’s fastest pure Java image processing program • Clean user interface • Active online forum provides support for both users and developers • Easy correction of improperly positioned patient scans • Structures can be easily mirrored from the healthy onto the defective side No

Yes (Open source)

Yes (Open source) Yes (Open source) No

http://carestreamdental.com/us/en/ imagingsoftware/3D-Software https://www.slicer.org/

http://imagej.net

http://www.itksnap.org/ https://www.brainlab.com/en/surgeryproducts/overview-ent-cmf-products/ iplan-cmf-straightforward-planning-andnavigation/

No

Free to use? No

http://www.planmeca.com/Software/Desktop/ Planmeca-Romexis/

Website http://www.i-cat.com/products/i-cat-software/

164 14  Future of Surgery-First Orthognathic Approach

Materialise

Mimics Care Suite

Konica Minolta Vivid Konica Minolta 910 3D Laser Scanner

Amira

Analyze

Maxilim

Voxim

3dMD vultus

15

16

17

18

19

20

21

Atlanta, GA

IVS Solutions, Chemnitz, Germany

AnalyzeDirect, Lenexa, Ann Arbor, MI Medicim, Bruges, Belgium

Visage imaging Inc., Carlsbad, CA

Company MathWorks

Sr. No. Software name 14 MATLAB® Highlight • Able to develop, test, refine, and implement algorithms to improve image processing workflow • Plan for orthognathic procedures and soft tissue simulations • Generation of design CAD data from physical models • Capture of data for finite-element analysis • High-speed scan time (77,000 points in 0.3 s) • 3D reconstruction • Support 3D navigation devices • Fast multithreaded and distributed rendering • Advanced image visualization and volume rendering • Multimodality image fusion • Specializes in maxillofacial surgery • Specific for craniomaxillofacial procedure • Volume-based registration • Virtual osteotomies possible at cross-­ sectional image views • Specializes in oral and maxillofacial surgery • Customized 3D prints No

No No No No

Thermofisher.com/Amira-avizo

https://analyzedirect.com/analyzepro/ www.medicim.com Voxim.software.com www.3dMD.com

(continued)

No

No

Free to use? No

http://www.materialise.com/en/medical/ mimics-care-suite http://sensing.konicaminolta.us/

Website https://www.mathworks.com/solutions/ medical-devices/medical-imaging.html

14.2  3D Image Acquisition and Diagnosis 165

Avizo

3Diagnosys

OnDemand3D

Blender

InVesalius3

23

24

25

26

27

Sr. No. Software name 22 Surgicase CMF

Table 14.1 (continued)

InVesalius

Blender Foundation

CyberMed, Seoul, Republic of Korea

3diemme, Cantu, Italy

FEI Visualization Sciences Group

Company Materialise, Leuven, Belgium

Highlight • Image segmentation system • Simulating/evaluating surgical treatment options • 2D/3D alignment of image slices • Surface and volume meshes generation • Interactive visualization • Soft tissue deformation simulation • 3D viewing, diagnostics, and 3D simulation • Surgical planning • Surgical replica for precise treatment planning • Customized template • High-end 3D software • Digital sculpting • Real-time control and rendering • Camera and object tracking • CT image reconstruction • Magnetic resonance images reconstruction

Free to use? No No

No No Yes (Open source) Yes (Open source)

Website www.materialise.com www.vsg3d.com

www.3diemme.it www.ondemand3d.com www.blender.org

www.cti.gov.br/en/invesalius

166 14  Future of Surgery-First Orthognathic Approach

14.3  Virtual Surgical Planning (VSP)

167

inbuilt metal deletion technique (MDT) that automatically reduces artefacts emanating from the aforementioned reasons, it is still prudent to incorporate an intra-­ oral scanner (TRIOS® 3 shape Copenhagen, Denmark) to scan the intra-oral l region and superimpose the intra-oral scan on the CT scans. Several intra-oral scanners are available for the recordings of the dental arches. All three imaging modalities such as CBCT (for osseous structure scan), 3D photogrammetry/non-contact laser scanner (for soft tissue scan), and intra-oral scan (for dental arches) are superimposed and registered for the creation of a virtual ‘composite maxillofacial-dental’ [15] or a ‘skull-dental composite’ [16] 3D working model. Subsequently, ‘virtual surgical planning’ is carried out on the composite model.

14.3 Virtual Surgical Planning (VSP) The virtual surgical planning is performed on a computer having surgical planning software. Several simulation software are available for the virtual surgical simulation for jaw surgery. Some of the commonly used software are listed in Table 14.1. These software are capable of several functions including (Figs. 14.2 and 14.3): (a) Image segmentation (from DICOM files to region of interest). (b) 3D cephalometric and anthropometric analysis. (c) Repositioning of osteotomy segments according to the surgical plan. (d) Evaluation of occlusion. (e) 3D surface photomapping and soft tissue simulation. (f) 3D surgical splint design. The VSP software can be seamlessly integrated into the computer networks across the hospital or teaching institutions such that the ‘surgical plan’ can be remotely accessed by the surgeon in the operating room and viewed in the clinic to

Fig. 14.2  VSP seamlessly integrates soft tissue and hard tissue and allows execution of planned surgery. Also, 3D surgical splint design can be visualized for ‘accuracy and fit’ before the 3D splints are printed

3D printed Wafer

3D Printer-Steriolithography System

Virtual Surgical Planning Software

Proplan Software

Fig. 14.3  Summary of 3D SFOA planning using CAD/CAM technology

Immediate post-surgery Outcome

CBCT scan

3dMD Photogrammetry System

Photogrammetry System

Summary: 3D SFOA Planning : CAD/CAM Technology

Virtual Splint/Surgical Wafer

Jaw Surgery Virtual Planning Outcome

Trios 3 Shape Intraoral Scanner

168 14  Future of Surgery-First Orthognathic Approach

14.4  ‘Tools of Transfer’ for Surgery Planning

169

inform the patient and in the classrooms for training and education. VSP allows the surgeon to visualize and prepare for the potential difficulties that might be encountered during the actual surgery, thereby reducing the possible surgical complications and post-surgical morbidity [3, 8, 17]. VSP significantly reduces the time required for treatment planning of jaw surgery cases to as much as 91% in comparison to non-digital surgical planning methods [18].

14.4 ‘Tools of Transfer’ for Surgery Planning Pascal et al. described ‘transfer methods or tools’ available for surgical planning into six categories, namely, (1) freehand surgery, (2) traditional handmade acrylic splints (HMAS), (3) CAD/CAM splints, (4) CAD/CAM splints with extra-oral bone-borne support (EOBS) or custom-made fixation miniplates (CFMP), and (5) surgical navigation CAD/CAM splints [19]. Once the final surgical plan is established, the construction of surgical splints could either be done by analogue method or digital-assisted method. The ‘digital surgical splints’ are transferred to a stereolithography (STL) file format for the creation/printing of actual surgical splints. The STL is a commonly used computer-aided design (CAD) format for rapid prototyping, 3D printing, and computer-aided manufacturing (CAM) [17, 20]. Several 3D printers are commercially available for the manufacturing of surgical splints, such as Stratasys (Stratasys, MN, USA), voxel 8 (Voxel 8, Suite 8 Somerville, MA, USA), Simplify3D software (Cincinnati, OH, USA), Three D Systems software (3D Systems Corporation, USA), and Tizian Creativ RT (Schutz Dental, Rosbach vor der Hohe, Germany). The printed surgical splints are used in the operating theatre for fixation of the planned osteotomy and the positioning of the jaw.

14.4.1 CAD/CAM Splints with Extra-Oral Bone-Borne Support (EOBS) Jaw surgery performed using surgical splint with extra-oral bone-borne support (EOBS) holds an important place for surgery-first orthognathic approach for the following reasons: 1. Elimination of error-prone and time-consuming treatment planning steps, such as face-bow transfer, cephalometric assessment, and model surgery [5]. 2. Elimination of positioning devices such as surgical splint that takes dental occlusion into account for the stabilization of osteotomy cuts. The non-dependency of occlusion for surgical fixation is an added advantage, especially in SFOA cases, as there is usually suboptimal intermaxillary cuspation for the proper fit of the surgical splint. 3. Extra-oral bone-borne support splint relies on several techniques such as: (a) Patient-specific implants (PSI) are manufactured via CAD/CAM technology and are used when fixing the repositioning of the maxillo-mandibular ­complex [5].

170

14  Future of Surgery-First Orthognathic Approach

(b) Interactive image-guided visualization display (IGVD) to transfer virtual maxillary planning precisely in real time [7]. (c) CAD/CAM enabled fabrication of ‘surgical cutting guides’ and ‘titanium fixation plates’ that allow maxilla reposition accurately without a ‘surgical splint’ [21, 22].

14.5 3D Printing/Rapid Prototyping in Surgery 3D printing, also known as additive manufacturing or rapid prototyping, is a revolutionary method of reconstruction of a 3D object by using 3D printing processes such as stereolithography (SLA), selective laser sintering (SLS), fused deposition modelling (FDM), MultiJet printing (MJP), ColorJet Printing (CJP), Plastic Jet Printing (PJP), and Direct Metal Printing (DMP) using a wide variety of materials. Some of these materials include acrylic, silicone, plaster, hydroxyapatite, and cobalt chromium [23, 24]. 3D printing has made tremendous advancements that we are able to better visualize malformations (77%), enhance refinement in guides and templates (53%), decrease operating time (52%), and have positioning improvements and even improvement in the transfer of information to patients (13%). The downside of 3D printing still revolves around the cost of the equipment, additional preoperative planning, untoward reaction of the print material, and complex coordination. These are the usual barriers that hinder the adaptation of using 3D printing [25–27].

14.6 Augmented Real-Time and Virtual Surgical Navigation 3D-assisted surgical navigation is a surgical modality based on synchronizing the intraoperative position of the surgical instruments with the 3D images of patient’s craniofacial structures (Table 14.2) [28, 29]. Extra-oral reference points (fiduciary markers) of the patient are used as navigation points and are synchronized with the virtual points on the reconstructed patient’s image (point to point registration) on a ‘navigator screen’ of proprietary navigation software [30]. Several surgical navigation software are commercially available and are listed in Table  14.2. Real-time navigation has many potential applications in the field of jaw surgery, such as (1) tracking the precise location of the surgical instrument, thereby reducing damage to the critical neurovascular tissues; (2) help to position the osteotomized bony segments in a planned position, hence reducing positioning errors; (3) offset the usage of two splints (intermediate splint) in two-jaw surgical cases, as the movements of the maxilla can be controlled by the navigation probe system; and (4) the surgeon can control the maxilla-mandibular complex freehand in 3D space with the aid of the surgical navigation system, hence providing adequate accuracy for a highly precise surgery [2, 31]. Advancements in the augmented real-time and virtual surgical navigation have prompted more companies to invest in this field which is estimated to have a market capitalization valued at USD 734.5 million, and it is projected to see a rise in the demand for surgical navigation systems in the near future [32].

Polaris Spectra

StealthStation AxiEM System

Stryker NAV3i Navigation Platform

Curve™ Image Guided Surgery

2

3

4

5

Brainlab AG (Olof-Palme Straße 981,829 Munich, Germany)

Stryker® (Stryker Global Headquarters 2825 Airview Boulevard Kalamazoo, MI 49002 USA)

Medtronic, Inc. Surgical Technologies, Neurosurgery (826 Coal Creek Circle Louisville, CO 80027 USA)

NDI Medical Solutions (103 Randall Drive Waterloo, Ontario, Canada N2V 1C5)

Name of the navigation system platform Company 3D Guidance trakSTAR Ascension Technology Corporation (120 Graham Way, Suite 130 Shelburne, VT 05482 USA)

Sr. No. 1

Table 14.2  Surgical navigation systems

Highlight • 3D electromagnetic tracking system boasting reliability, versatility, and ease of use • Up to four sensors provide optimal tracking volume for 3D medical navigation applications • Advanced tracking algorithms provide exceptional accuracy • Able to track both active and passive wireless tools • Adheres to patient’s skin, eliminating the need for a head holder • Flexibility using a simple plug and play design • Navigation camera arm with large range of motion • 32″ high-definition surgeon’s monitor with HDMI output • Can be used in conjunction with eNlite system as a mobile platform to secure the camera and monitor • Two 27″ monitors with 16:9 screen ratio • 1920 × 1080 pixels per display providing full HD screen resolution • Smart ergonomics allow easy transportation and storage in the operating theatre

(continued)

No https://www.brainlab.com/ en/surgery-products/ overview-platform-products/ curve-image-guided-surgery/

No

No

http://www. stealthstationaxiem.com/ http://www.stryker.com/ en-us/products/ OREquipmentConnectivity/ SurgicalNavigation/ SurgicalNavigationSystems/ Nav3i/index.htm

No

http://www.ndigital.com/ medical/products/ polaris-family/

Website http://www.ascension-tech. com/products/#3d-guidance

Free to use? No

14.6  Augmented Real-Time and Virtual Surgical Navigation 171

Instatrak

VoNaviX (IVS Solutions, Chemnitz, Germany)

7

8

Highlight • Optical tracking system • Contoured-based registration • Paired-point registration GE Health Care, Buckinghamshire, UK • Global positioning system • Uses optical technology to locate surgical instrument in 3D space Renishaw Innovation • Stereotactic angular and spatial positioning of surgical instruments

Name of the navigation system platform Company Vector vision Brainlab, Westchester, IL

Sr. No. 6

Table 14.2 (continued) Free to use? No No No

Website www.brainlab.com www.gehealthcare.com www.renishaw.com/neuro

172 14  Future of Surgery-First Orthognathic Approach

References

173

14.7 Conclusion As advancement in technology brings further refinement to computer-aided surgical simulation, it will not be long before this will replace the manual or analogue methods of planning. As the cost of rapid prototyping and 3D printing comes down and further refinements are made to the usability and accessibility of such systems, it will make the practice of SFOA easier, more efficient, and safer for both patient and practitioner alike.

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