Biomechanics in clinical dentistry

Biomechanics in clinical dentistry

J. Dent. 1989; 43 17: 43-46 Book Reviews Section Editor: P. N. Hirschmann Perspectives in Temporomandibular Disorders. Glen T. Clark and William ...

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J. Dent. 1989;

43

17: 43-46

Book Reviews Section

Editor: P. N. Hirschmann

Perspectives in Temporomandibular Disorders. Glen T. Clark and William K. Solberg. Pp. 147. 1987. New Malden, Quintessence. Hardback, f 32.50. Killing Pain without Prescription. Harold Gelb and Paula M. Siegel. Pp. 246. 1987. Wellingborough, Thorsons. Softback, f 2.99. The rate of change in investigational techniques, diagnosis and treatment of TMJ disorders is now so rapid that it is important a reputable review is produced at frequent intervals, in particular since this is an area which continues to be a source of much confusion to the many clinicians who treat, but do not specialize, in these problems. In this context Clark and Solberg’s book is a valuable contribution both for its content and as an excellent source of current references. A brief overview of TMJ and associated muscle disorders and their causes, and of diagnostic and treatment aspects, is followed by more detailed discussion of selected topics. The UCLA Temporomandibular Joint Studies Group has a unique collection of TMJ cadavers from young adults which, together with clinical data derived from patients and pathological specimens obtained at surgery, has provided an important data-base. Almost 90 per cent of the cadavers displayed visible degenerative change in at least one joint component, and the dilemma for the clinician is that the significance of these findings cannot be determined: are such localized changes the sequel to previous injury rather than a stage in a progressive degenerative condition? There are detailed sections on radiography and arthrography, although some illustrations of the latter are too small to be useful. The indications and contraindications for arthrography are discussed, and, in particular, the rationale for a bilateral examination in patients with unilateral symptoms, a topic of special significance for both treatment planning and its medicolegal implications. The data on condyle/fossa relationship in normal and symptomatic joints are analysed but, although some significant differences are noted, much remains to be done before the clinical significance can be established. More data is also required before it is possible to judge the long-term success of arthroplasty in their patients. An attractive feature is the discussion which follows each chapter. Perspectives in Temporomandibular Joint Disorders is produced to the high standard characteristic of Quintessence and I would hope it will prove to be the first of a series, each dealing with individual topics in greater depth. Dr Gelb’s book, on the other hand, is characterized by sweeping statements and unsupported claims. He discusses backache, nutritional and hormonal balance as well as TMJ problems and there is a useful section on exercizes for various groups of muscles, including those 0 1989 Butterworth & Co. Publishers 0300-57 12/89/010043~4 $03fIO

Ltd.

of the hip, abdomen and back; it also introduces the reader to ‘applied kinesiology’ and ‘cranial osteopathy’ which apparently have much to offer in the diagnosis and treatment of TMJ disorders, although this reviewer remains highly sceptical about the claims made for them in the light of Gelb’s descriptions. The final chapter is devoted to individual case histories, 18 of them, which detail a variety of types and duration of symptoms and previous failed treatments. In each case Dr Gelb is mentioned by name as the clinician who eventually relieved these patients of their suffering when all else had failed. It is wholly acceptable, indeed laudable, that a clinician writes a book on a specialized medical topic for the lay reader or patient, but whether this should extend, as here, to publicizing such a highly personalized clinical role for its author is debatable. Dr Gelb’s book may serve a useful purpose in bringing to the attention of the lay public that TMJ problems could be responsible for a variety of apparently unrelated clinical signs and symptoms, but I would not wish to recommend it to colleagues, junior staff or patients. A. A. Quayle Biomechanics in Clinical Dentistry. Angelo A. Caputo and Jon P. Standlee. Pp. 224. London, Quintessence. Hardback, f46-50.

1987.

This book attempts to bring together the various engineering and physical principles underlying the design of dental restorations and appliances, and is aimed at both students and practitioners. It fulfils a long-felt need, for the mechanical principles involved apply equally well to all branches of dentistry, and are a necessary complement to the study of dental materials. Dental biomechanics, as the subject may be called, has matured rapidly as our knowledge of the behaviour of the oral tissues to the stresses to which they are subjected and our ability to adequately describe this behaviour have both gradually improved. Not very surprisingly, the mathematics involved is complex as is the interpretation of some of the more sophisticated techniques employed and research in this area is mainly confined to basic scientists. The authors have attempted to convey the results of the various stress analyses by photographs of the fringe patterns obtained with the photoelastic technique on models constructed of a suitable birefringent material. Most of the coloured and some of the black and white photographs adequately convey the areas of stress concentration, but the contrast in the remainder is often poor and fails to convince. The material they present reflects, perhaps understandably, the authors’ research interests and is limited to selected topics within each speciality, thus creating an unfortunate imbalance. The biomechanics of complete dentures, for

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J. Dent.

1989;

17: No. 1

instance, is concerned mainly with an elementary discussion of denture retention and allotted four pages, whereas a whole chapter is devoted to the biomechanical aspects of endodontic dowels. However they do approach each topic from a practical viewpoint, and if, as they hope, they succeed in kindling their readers’ enthusiasm, then the purchase of this (generally) well-presented book will be money well spent. N. E. Waters Lecture Notes on Clinical Medicine and Surgery for Dental Students, 3rd edition. Edited by D. MacLean and P. E. Preece. Oxford, Blackwell Scientific. Softback, f 9.80 As a student I found my own lecture notes tedious to read, others even more so. As a result, I have never been excited by the prospect of the format ‘Lecture notes on. . .’and in that sense this book fulfils my pessimistic expectations. However, while lacking in sparkle, it is well planned and comprehensive. Twenty-nine authors contribute the 26 short chapters yet the style is reasonably uniform, something of an achievement in itself. The bulk of the book is devoted, in a systematic fashion, to internal medicine and surgery, but there are some more original and thoughtful chapters such as, for example ‘First aid, emergency management and trauma’, ‘Immunity, immune deficiency, hypersensitivity and immunization’, ‘The elderly’, and ‘Fitness for surgery and anaesthesia’. As the editors point out in their preface, these were topics picked out for more detailed attention in the medical and surgical curriculum for dental students at a consensus conference in 198 1. In general, the text is succinct, sound and sensible, but I do have a few rhetorical questions for the editors. Why have an opening chapter on ‘History and examination’ in which there is less information on how to take one than in that on fitness for surgery? Why, in the same chapter, provide a list of physical findings without any explanation of their relevance? By what process of selection are two of the 12 illustrations a cross-section of an artery with atheroma and a line drawing of the hand in hypocalcaemia? Is it really sensible to cover cerebrovascular disease in three sections, once under cardiovascular diseases, and twice again in neurological disorders? In the preface the editors describe their intention as teachers of medicine and surgery to dental students ‘to broaden the basis of professional education. . . helping them to understand new advances and to encourage continued learning’. I think their book goes some way to achieving the first two although I am less certain whether its style inspires further study. As a basic text for dental students, it serves its purpose well enough and will certainly appear on my list of recommended textbooks. Andrew Davies Dental Technology and Materials for Students, 8th edition. H. J. Wilson, M. A. Mansfield, J. R. Heath and D. Spence. Pp. 634. 1987. Oxford, Blackwell Scientific. Softback, f 27.50. This textbook now spans half a century and has changed considerably since it first appeared in 1939 as ‘Dental Mechanics for Students’ by John Osborne. Two new authors (Heath and Spence) have been co-opted for the production of this eighth edition which is now designed as an introduction to technology in the area of restorative

dentistry. Materials, their handling and their clinical use, are set out together in sections; since the field covered is obviously very wide, details are limited. The text is clear, well written and easy to follow. The line diagrams are excellent, some of the photographs less so. The fact that materials are so closely linked with clinical explanations of treatment does result in some repetition. An attempt has been made to introduce new techniques, such as adhesive bridges, and current concerns over the prevention of cross-infection when handling impressions and other laboratory work are considered. However, there is little mention of current research and, although further reading is encouraged, there is no reference section. Several chapters are very helpful, for example, that on mandibular movement and position, which is particularly clear and concise with many excellent diagrams and photographs. Overall, the materials component of the book is a significant improvement on the seventh edition and the authors have succeeded in presenting an integrated approach to dental technology, but clinical coverage has been achieved only at the expense of sufficient detail for any other than junior undergraduates. C. J. Watson

Clinimetrics. Alvan R. Feinstein. Pp. xi + 272. 1987. University Press. Hardback, f 25.00.

London, Yale

Clinimetrics means what it implies, the science of clinical mensuration, a discipline concerned with the development of indices and scales for measuring ‘distinctly clinical phenomena’, such as symptoms, signs and human sensations and reactions. Such evidence, the author argues, is undervalued by current practice, dominated as it is by a scientific paradigm favouring the hard, dimensional data yielded by technological investigations. This is the nub of the book, that ‘the omission of soft clinical information is detrimental for. . . modern medicine’ and Feinstein sets himself the task of augmenting the standard of clinical measurement by developing a coherent discipline of strong theoretical principles and well-defined methods for what, he claims, has hitherto been a loose collection of ad hoc practices. Clinimetrics, the argument goes, is a supremely judgemental rather than empirical activity in which two principles are uniquely important: first, that clinical intuition (through a process of critical reflection, or ‘dissection’) is the prime determinant of what should be included in a clinimetric index; and, second, that a key factor governing the fusion of variables in the final index is clinical plausibility (‘biological coherence’). An important theme of the book is that statisticians and psychosocial scientists, who are often collaborators in clinical research, have different methodological perspectives, and Feinstein sets out in two chapters to improve matters ‘by bringing open recognition of the different basic goals and policies of. . . statistical, psychosocial and clinical investigators’. In discussing statistical methods, he observes, without irony, that ‘a clinician may have problems in trying to understand and interpret mathematical expressions’: he certainly will after reading this review which is shot through with so many misconceptions and incoherent, vaguely poetic, notions. The argument is pursued that clinimetrics is a fundamentally different activity from bio- and psychometrics (any other -metrics for that matter). What is different he encapsulates in a new concept called, rather egregiously, ‘sensibility’. Sensibility is apparently