Table Of Content

/■ 3 4067 03176 6719 DIAGNOSTIC PRINCIPLES Third Edition Terrence J Freer BDSc, D.ORTH, FDS, FRACDS, FICD, PhD Emeritus Professor of Orthodontics Christopher TC Ho BDSc (Hons), MDSc, MRACDS (Orth) t Associate Professor of Orthodontics School of Dentistry University of Queensland Or O Third Edition Emeritus Professor Terry Freer BDSc, D.ORTH, FDS, FRACDS, FICD, PhD Emeritus Professor of Orthodontics Associate Professor Christopher T.C. Ho BDSc (Hons), MDSc, MRACDS (Orth) Head, Discipline of Orthodontics School of Dentistry, The University of Queensland St Lucia, 4072 Australia The University Of Queensland AUSTRALIA -A'D LIBRARY Acknowledgements Appliances used in the textbook were constructed by Paul Chapman, Danny Kuys, Angelo Mathews and the Children’s Oral Health Service. Published by the School of Dentistry The University of Queensland St Lucia, 4072 Australia First Published 1997 Second Edition 1999 Third Edition 2009 ISBN 978 1 86499 939 6 Original design and diagrams by Kira Hogg Layout by Jerry Liu Design and Photography The University Of Queensland A U S T R A L 1 A Authors Emeritus Professor Terry Freer BDSc, D.ORTH, FDS, FRACDS, FICD, PhD Emeritus Professor of Orthodontics I, Associate Professor Christopher T.C. Ho BDSc (Hons), MDSc, MRACDS (Orth) Head, Discipline of Orthodontics School of Dentistry, The University of Queensland St Lucia, 4072 Australia Contributors Stephen Atkin, Rodney Auer, Hugh McCallum, Gavin Lenz Children’s Oral HealthService, Royal Children’s Hospital, Brisbane, Australia. Craig W. Dreyer School of Dentistry, The University of Adelaide, Adelaide, Australia. Brett Kerr School of Dentistry, The University of Queensland, Brisbane, Australia. Murray C. Meikle Faculty of Dentistry, National University of Singapore. Peter G. Miles 10 Mayes Avenue, Caloundra, Queensland, Australia. Richard Olive 141 Queen Street, Brisbane, Australia. Desmond C-V. Ong School of Dentistry, The University of Queensland, Brisbane, Australia. Pamela Wong 3215 Logan Road, Underwood, Queensland, Australia. Contents 1 INTRODUCTION 1 2 POST-NATAL CRANIOFACIAL GROWTH 5 3 RADIOGRAPHIC CEPHALOMETRY 21 4 CHARACTERISATION AND CHANGE 37 5 FUNCTION 53 6 DEVELOPMENT OF OCCLUSION 71 7 OCCLUSAL RELATIONSHIPS 93 8 CLASSES AND CATEGORIES 111 9 EXTRACTIONS 125 BIOLOGY OF TOOTH MOVEMENT 10 137 Craig l/IZ Dreyer and Murray C. Meikle 11 BIOMECHANICS OF TOOTH MOVEMENT 159 PRINCIPLES AND MANAGEMENT OF 12 181 REMOVABLE APPLIANCES 13 FIXED APPLIANCES 211 SEQUENTIAL PLASTIC ALIGNERS 14 233 Brett Kerr LOCALISED ANOMALIES 15 243 Ectopic Teeth by Richard Olive 16 DEMAND. NEED AND MANAGEMENT 275 17 PRINCIPLES OF CLASS II MANAGEMENT 293 18 CLASS II DIVISION 1 MALOCCLUSION 305 19 CLASS II DIVISION 2 MALOCCLUSION 331 20 CLASS III MALOCCLUSION 349 FUNCTIONAL APPLIANCES 21 369 Desmond C-V. Ong THIRD MOLAR ASSESSMENT 22 389 AND MANAGEMENT PHARYNGEAL AIRWAY 23 397 Peter Miles 24 ORTHOGNATHIC SURGERY 407 RETENTION, RELAPSE AND STABILITY 25 425 Pamela Wong 26 PATIENT EXAMINATION 435 CLINICAL MANAGEMENT OF PATIENTS WITH CLEFT LIP AND PALATE 27 449 Christopher T.C. Ho, Stephen Atkin, Rodney Auer, Hugh McCallum, Gavin Lenz CASE BASED EXERCISES 28 473 Desmond C-V. Ong GLOSSARY 491 INDEX 499 Preface to Third Edition A useful textbook represents the outcome of pragmatism versus idealism. Lengthy qualifications and arguments are simply not instructive at the undergraduate level. The broad contributions of authors in this edition provide a balanced compilation of information which is firmly grounded. They come from diverse educational and clinical backgrounds and yet have produced a cohesive and consistent resource. I would like to thank them all. The book reflects evidence-based mainstream orthodontic teaching and provides the stimulus for progressive learning throughout the dental student’s journey to graduation. The material is comprehensive but not overwhelming. The educational experiences of undergraduates are considerably enhanced by reference to a consistent central source of knowledge which is not outrageously expensive. There is little benefit in different instructors using different classifications of malocclusion or variously interpreting the current evidence on the effects of functional appliances. Undergraduates are subjected to onerous time demands and can become lost in a sea of information, some of which is irrelevant. In addition, universities are moving inexorably toward standardised digital teaching strategies. A balanced textbook offers a valuable resource in this chameleon-like environment. I believe the book also provides a useful starting point for postgraduate candidates in-so-far as it emphasises a basic level of knowledge with which they ought to be familiar prior to expanding their perspectives with closer study of the published literature. It is my experience that postgraduate candidates often seek to serve many masters and fail to grasp the importance of basic and often simple facts. Some also fail to develop the skills of simplifying and summarising extensive information sources in an understandable and clinically applicable form. This third edition is essentially similar to the previous editions and the design, layout and line drawings are products of the hard work of Kira Hogg and I thank her once again. Survival to a third edition suggests a continuing relevance. I also thank Chris Ho for his commitment, good humour and considerable effort in launching this third edition. Without his contribution it would not have happened. He has been the prime mover in rewriting some of the text, obtaining updated clinical illustrations and encouraging other contributors. TJF o Introduction Orthodontics is that branch of dental science concerned with the study and treatment of dentoskeletal anomalies associated with the growth, development and function of the dentofacial tissues and structures. The ultimate objective of most orthodontic treatment is an occlusion which functions normally, maintains oral health and enhances facial appearance. Normal occlusion is a variable concept rather than a rigidly defined state. An occlusion which functions comfortably, has an acceptable appearance, does not require undue maintenance and does not jeopardise oral health may be regarded as normal. As a conceptual starting point it is easier to define ideal occlusion. However, many occlusions which depart from the definition of ideal may still be regarded as normal. Clinicians are required to make treatment recommendations based on their experience, knowledge and the patient’s preferences. The general practitioner must employ considerable skill in assessing the needs of every patient. Competent assessment requires an understanding of the patient’s background and aspirations. The dentist is usually familiar with the patient’s medical and dental histories and how they might influence compliance. Orthodontic treatment need is sometimes modified by more pressing personal or socio-economic factors. The practitioner must make a decision, in consultation with the parent and patient, whether to provide treatment personally, refer for specialist service or recommend no treatment at all. Assuming a competent diagnosis, the single most important factor determining the success of orthodontic treatment is patient cooperation. Few orthodontic treatment plans can succeed without it and experienced orthodontists devote considerable expertise to ensuring that the effects of poor compliance are minimised. Orthodontic treatment for the unwilling patient may be better postponed to a later time. Usually gingival inflammation and decalcification or caries are the direct consequences of poor oral hygiene. Additionally, non-compliant patients are often poor attenders so that orthodontic treatment becomes prolonged and in rare instances may even become unpleasant for both the patient and the clinician. With the widespread availability of orthodontic treatment, the need for compliance is underestimated or ignored by many patients. Where the primary decision to commence treatment is made by the parent, compliance by the patient is often below expectations. Where compliance is poor, the clinician may well judge that it would have been better not to have commenced treatment - a judgment usually made infallibly in hindsight. 1 Orthodontic Diagnostic Principles The discipline of orthodontics presents a particular educational challenge in the undergraduate curriculum both in terms of content and the time set aside for orthodontic instruction. Competent orthodontic treatment relies upon competent case assessment and competent case assessment depends upon a broad understanding of the morphological and functional concepts of normality. The student must be taught to integrate knowledge from virtually every dental discipline in formulating a diagnosis and treatment plan. The objectives of treatment are related not only to the immediate orthodontic problem but also to those matters which impinge on treatment planning, including dental health status, cooperation and compliance, family support, geographical factors and cost. Because most orthodontic treatment is protracted the clinician is often, by default, expected to supervise management of the patient’s oral health during the course of treatment. The time available for orthodontics within the undergraduate curriculum is necessarily limited by the legitimate demands of other disciplines. Many critics of new graduates and even the graduates themselves do not always appreciate that there is keen competition by many disciplines for time in the curriculum. Furthermore, the content of the undergraduate curriculum has changed substantially in recent times with the full implementation of courses in gerodontology, dentistry for the handicapped, gnathology, implantology, infection control and others. All of these components have been added into the traditional mix so that demands on the student’s time have become acute, particularly in the clinical years. Some members of the profession have suggested a period of pre-registration vocational training to ensure the maintenance of clinical standards. The undergraduate orthodontic curriculum is usually directed to giving the student the ability to discriminate between simple and complex cases thereby encouraging the new graduate to restrict treatment to simple one dimensional objectives. The problem is that the treatment of virtually any orthodontic anomaly, even the simple one, may present difficulties which were completely unsuspected at the start and later require the implementation of strategies which may be outside the capabilities of the operator. For example, many texts use the single tooth anterior crossbite as an example of an anomaly which might be simply corrected by means of a removable appliance. However, this simple anomaly is often complicated by a lack of arch space, palatal displacement of the root apex or an underlying prognathic mandibular tendency which will become worse with skeletal development. What seemed to be a simple treatment problem may become a significant clinical and technical challenge. This example highlights the dilemma of the orthodontic teacher who strives to provide the undergraduate with a scientifically grounded methodology yet knows that often it may not be enough to enable the general dental practitioner to confidently predict clinical difficulties, responses or treatment outcomes. Orthodontic teachers, and orthodontists in general, assume a cautious approach to diagnosis and treatment planning and this caution is often misinterpreted. However, the need for caution is substantiated by the present climate of increasing litigation and consumer advocacy. Additionally, the provision of orthodontic treatment is complicated by the concept of need to improve oral health or psychosocial status. 2