Medical knowledge | Dentistry » Christopher-Finbarr - The combination syndrome revisited

L N E T IPCRS O S T H O D O N T I C S R E M O V A B L E RPER M O SOTVHA OB DO The ‘Combination Syndrome’ Revisited CHRISTOPHER D. LYNCH AND P FINBARR ALLEN Abstract: The ‘combination syndrome’ may present a considerable clinical and technical challenge to the dental practitioner. This clinical scenario classically relates to changes found in the mouth following use of a maxillary complete denture that has opposed natural mandibular anterior teeth. While this condition was first recognized over 30 years ago, the associated difficulties still pervade the practice of prosthetic dentistry today. The purpose of this article is to describe treatment of two patients who exhibited clinical features of this condition, and review some of the relevant literature on this condition. Dent Update 2004; 31: 410–420 Clinical Relevance: For a variety of sound dental, medical and financial reasons, conventional prosthodontics still has much to offer in the oral rehabilitation of patients

presenting with combination syndrome. T he prosthodontic rehabilitation of an edentulous arch which opposes natural or restored teeth may present a considerable clinical challenge to the dental practitioner. Potential clinical problems encountered may include: l Exaggerated horizontal inter-ridge discrepancies (artificial teeth are usually set ‘off’ a resorbed ridge in complete denture prosthdontics, however, this is more exaggerated when opposing natural teeth to produce a satisfactory occlusion);1 l Problems of varying support (anterior maxillary ‘flabby ridge’ thought to be caused by differential Christopher D. Lynch, BDS, MFD RCSI, Registrar in Restorative Dentistry and P. Finbarr Allen, BDS, MSc, FDS RCPS, PhD, Senior Lecturer/Consultant, Department of Restorative Dentistry, National University of Ireland, Cork, Ireland. 410 forces on an edentulous ridge caused by a partially dentate opposing arch);2 l Enlarged maxillary tuberosities (limiting the correct orientation

of the occlusal plane and the amount of inter-ridge space available for positioning prosthetic teeth).1,2 This scenario was first described by Ellsworth Kelly in 1972, who described the ‘changes caused by a mandibular removable partial denture opposing a maxillary complete denture’.2 Naming this condition the ‘combination syndrome’, he described the common clinical features, namely: l Resorption of the maxillary labial plate (leading to a flabby maxillary anterior ridge); l Overgrowth of the maxillary tuberosities; l Papillary hyperplasia of the hard palate; l Extrusion of the lower anterior teeth; l Resorption of mandibular bone under the partial denture bases (if worn). Kelly proposed that this scenario was caused by what is commonly termed insufficient ‘posterior occlusal support’, leading to increased occlusal forces on the anterior part of the maxillary complete denture by remaining anterior natural teeth. He felt that these forces led to resorption of the maxillary

labial plate, and subsequent ‘tipping’ downwards of the posterior section of the maxillary complete denture into which the tuberosities enlarged due to ‘negative pressure’. Kelly advised the prevention of this condition through the use of impression techniques that distributed forces evenly across the edentulous ridge, and by the provision of an appropriate occlusal scheme. Recognizing the significance of this latter factor, he advocated retention of natural mandibular posterior teeth (including those that were ‘weakened’ and requiring ‘endodontic and periodontic’ treatments). Failing this, ‘endosseous endodontic implants’ and removable prostheses were indicated.2 Although this condition was first described over 30 years ago, the problems described then are still pertinent today. Epidemiological studies report that ‘flabby ridges’ have been observed in up to one-quarter of edentulous maxillae – most frequently in the anterior maxilla3 – and that such

‘flabby ridges’ may also be found in Dental Update – September 2004 R E M OVA B L E P R O S T H O D O N T I C S Figure 1. Dental panoramic tomograph of patient in Case Report 1 association with enlarged maxillary tuberosities.1,2 Such enlarged tuberosities pose significant difficulty in achieving a correctly oriented occlusal plane – and this can adversely affect the stability and retention of the final prosthesis. The purpose of this article is to describe the prosthodontic management of two patients who presented with features of the ‘combination syndrome’. CASE REPORT 1 Figure 2. Primary maxillary cast made from preliminary alginate impression. Figure 3. Spaced maxillary custom tray including tissue stops. Dental Update – September 2004 A 60-year-old male was referred to the Department of Restorative Dentistry of the Cork University Dental School and Hospital (Cork, Ireland) for specialist dental implant treatment to overcome his difficulty with his existing

maxillary complete denture. The patient had a complicated medical history including rheumatoid arthritis, diabetes mellitus, sarcoidosis and mobility difficulties. The patient reported that his maxillary complete denture was ‘loose’. On examination, the patient had an edentulous maxilla and five natural mandibular anterior teeth. The entire maxillary ridge was quite mobile – offering compromised support for any complete denture resting on it (Figure 1). The lower anterior teeth were overerupted and periodontally involved. The maxillary tuberosities were enlarged, thereby reducing the amount of interridge space available for placement of prosthetic teeth. The patient reported that his maxillary arch had been edentulous for over 40 years, and he had had his existing mandibular dental configuration for a similar length of time. He reported that he had worn one mandibular removable partial denture for one year without success. Following clinical and radiographic examination, it was

evident that insufficient maxillary bone was available for placement of dental implants, and the prognosis for successful implant treatment was limited by the patient’s medical history. Following discussion with the patient regarding these factors, it was agreed to provide him with a new complete maxillary denture (utilizing a mucostatic impression technique), and a mandibular removable partial denture. However, as the mandibular neutral zone was compromised by lateral spreading of the tongue, it was considered essential that the tongue space should be maximized in the lower denture, and it was planned to achieve this by reducing the size of the occlusal table. Balanced articulation would also be indicated for these prostheses to ensure even distribution of occlusal forces on the residual ridges, and to avoid the introduction of ‘interfering’ or displacing contacts. Figure 4. Completed maxillary impression recorded using impression plaster. Figure 5. A heat-cured transparent

acrylic baseplate was fabricated on the resulting cast. 411 R E M OVA B L E P R O S T H O D O N T I C S Figure 6. (a) The completed prostheses (b) The completed mandibular removable partial denture. Note the narrow bucco-lingual width of the mandibular prosthetic teeth, and the omission of the mandibular molar prosthetic teeth. Considering the significance of this point, it was decided that incorporation of shallow-angled posterior prosthetic teeth would be useful. Non-surgical periodontal treatment was completed as necessary on the standing natural teeth. A preliminary impression of the maxillary and mandibular arches was made with a low viscosity irreversible hydrocolloid material (Alginate; Dentsply Ltd-UK, Weybridge, Surrey, UK), thus ensuring minimal distortion of the displaceable (‘flabby’) tissues (Figure 2). A spaced custom tray (three thickness of wax) was fabricated for the maxillary impression. Tissue stops were included in the design of the custom tray (Figure 3)

and modified using greenstick plastic impression compound (Green Impression Compound; Kerr UK Ltd, Peterborough, UK) to ensure accurate location of the impression tray. Careful attention was paid to border moulding the impression with greenstick plastic impression compound accurately (Green Impression Compound). An impression of the maxillary arch was made using impression plaster (Impression Plaster; Kerr UK Ltd, Peterborough, UK) (Figure 4). When complete, the impression was re-seated in the mouth to ensure its accuracy. A heat-cured transparent acrylic baseplate was fabricated on the resulting cast, and was tried in the mouth to ensure accuracy of fit and adequate retention before addition of a wax occlusal rim (Figure 5). A Kennedy Class I removable partial denture was designed for the lower arch. 412 Owing to the lack of labial undercuts on the abutment teeth, consideration was given to the provision of a ‘swing-lock’ denture. This was contra-indicated, however, by the

patient’s limited dexterity (caused by rheumatoid arthritis). Artificial undercuts were created using composite resin for retaining gingivally approaching clasps. Fabrication of this prosthesis was carried out in the usual manner. At the occlusal registration stage, careful attention was paid to the position of the labial surface of the maxillary rim. The upper lip was found to be ‘tight’ and exerting a powerful posterior displacing force on the wax rim. The palatal position and shape of the wax rim was limited by the position of the over-erupted mandibular anterior teeth. Consideration was also given to the bucco-lingual shape and distal extent of the mandibular wax rim to avoid ‘cramping’ the tongue. To avoid encroaching on the neutral zone and to improve the stability of the mandibular removable partial denture, it was decided not to replace teeth distal to the mandibular second premolars. It was noted that the posterior inter-ridge space was reduced but, as the prosthetic

mandibular molar teeth were omitted, it was possible to orient the occlusal plane correctly. Following facebow transfer, the technician was instructed to arrange the teeth in balanced articulation on a semiadjustable articulator (Denar Anamark Fossae; Teledyne Water Pik, Fort Collins, Colorado, USA), paying attention to even tooth contact in excursive movements. Protrusive occlusal balance was included at this stage to prevent ‘incisal locking’ and destabilization of the maxillary denture. The stability of this tooth arrangement was confirmed at the ‘try-in’ stage. The ‘altered-cast’ technique was carried out for the mandibular removable partial denture. The dentures were delivered and, at subsequent review appointments, the patient reported satisfaction with stability, aesthetics and function of both the maxillary complete denture and mandibular removable partial denture (Figures 6a, b). In summary, the key points of this treatment were: l Recognition of abnormal oral

anatomy (upper flabby ridge); l Identification of the necessity of specialized impression technique; l ‘Early’ assessment of stability/ retention/fit of complete denture by fabricating a heat-cured transparent baseplate prior to occlusal registration; l Omission of mandibular posterior prosthetic teeth; l Selection of shallow-angled cusped teeth; l Face-bow transfer – particularly useful in this case, allowing suitable orientation of the occlusal plane, and locating the arc of closure nearer to the hinge axis, reducing the likelihood of a premature contact; l Arrangement of teeth on a semiadjustable articulator to ensure balanced articulation. Figure 7. Intra-oral view of maxillary ridge of patient in Case Report 2. Dental Update – September 2004 R E M OVA B L E P R O S T H O D O N T I C S Figure 8. Dental panoramic tomograph of patient in Case Report 2 CASE REPORT 2 A 70-year-old male was referred to the Department of Restorative Dentistry of the Cork University Dental

School and Hospital, (Cork, Ireland) for specialist restorative dental treatment. On examination, the patient had an edentulous maxilla (Figure 7), and seven teeth remaining in his mandibular arch (namely, 7 3 2 | 2 3 4 5). The anterior portion of the maxillary ridge was found to be displaceable. The periodontal status of the mandibular teeth was poor – with almost 50% bone loss around each tooth (Figure 8). Extensive caries was evident in 3|, 2| and |2. The patient reported that he had worn four maxillary complete dentures over the last 40 years, wearing his existing prosthesis for over 10 years, and this had recently become ‘loose’. As a provisional treatment plan, it was decided to extract the 2| and |2 and to add these to the patient’s existing RPD. The 3| was to be retained as a possible overdenture abutment for a future prosthesis. Non-surgical periodontal treatment was also performed. The patient was discharged. At a review appointment held after six months, the patient

demonstrated good oral hygiene, and the periodontal status of the remaining mandibular teeth was judged to be stable. It was decided to formulate Dental Update – September 2004 a definitive treatment plan for this patient. The maxillary complete denture was to be replaced. As this prosthesis had served the patient reasonably well for many years (and considering the patient’s age), it was decided to use a ‘modified copy denture’ technique – thereby retaining the more favourable features of his prosthesis, and improving on those that were less than adequate. Careful thought had to be given to the impression technique utilized for the fitting surface of this denture – a standard wash impression in the duplicate base would cause compression of the flabby tissues, leading to possible future difficulties with the prosthesis. It was decided to provide the patient with a mandibular removable partial denture, maintaining the 3| as an overdenture. As the prognosis of 7| was guarded

(a 9 mm pocket was detected on its lingual surface), it was felt that the incorporation of a magnetic retention system on 3| would provide suitable retention for the RPD even after the eventual loss of 7|. Given the difficulties of the displaceable tissues on the maxillary anterior ridge, it was again necessary to ensure a proper occlusal scheme and balanced articulation was designed for the prostheses to avoid de- stabilizing ‘interferences’. A duplicate impression of the existing maxillary complete denture was made using a polyvinylsiloxane putty material (Provil Novo; Heraeus Kulzer, Hanau, Germany). The duplicate was made using a cold-cure acrylic base and wax teeth. The labial surfaces of the anterior teeth were adjusted so as to avoid the posterior displacing effect of the upper lip (as described also in Case Report 1). Tooth selection took place and the maxillomandibular relationship was recorded. Using face-bow transfer, the casts were mounted on a semiadjustable

articulator and the teeth were arranged in balanced articulation. Shallow-angled posterior teeth were again used to avoid introduction of destabilizing occlusal ‘interferences’. At the subsequent clinical appointment, the peripheral extent of the cold-cure acrylic base was examined and adjusted where necessary. The base over the flabby tissues was then perforated and an impression was made using light-bodied silicone (Extrude® polyvinylsiloxane Figure 9. Cast post and core, fabricated in palladium-cobalt for retaining magnetic precision attachment. Figure 10. Framework design of the mandibular RPD. 415 R E M OVA B L E P R O S T H O D O N T I C S that these should ‘record the entire functional denture-bearing area to ensure maximum support, retention and stability for the denture during use’.6 It follows that the definitive impression should accurately record the tissues of the denture-bearing areas, in addition to recording the functional width and depth of related

sulci.5,7,8 Two broad categories of impression techniques are generally described: the mucostatic (non-displacive) approach,9 or the mucocompressive (displacive) approach.10 Some authors have concluded that, while mucostatic impressions record the denture-bearing areas at rest (hence the fitting surface of the resultant denture represents the undisplaced denture-bearing areas and is theoretically more retentive), occlusal forces will not be as evenly distributed across the denture-supporting tissues as they are when an impression is recorded using a mucocompressive (tissue-displacing) impression technique. While there is no evidence to indicate that one technique produces better long-term results than another,7 certain clinical scenarios may be more suited to one particular technique. In the first clinical report described above, the entire maxillary ridge was mobile – hence a mucocompressive approach would considerably compress the denturebearing area, and the resulting prosthesis

would not be accurately adapted to the underlying tissues at rest. A particular problem may be encountered when the denture-bearing area contains both mobile and nonmobile tissues. Most ‘conventional’ treatment were: Figure 11. Magnetic attachment included on the fitting surface of the mandibular RPD. l Recognition of abnormal oral anatomy (upper anterior flabby ridge); l Identification of necessity of specialized impression technique (selective pressure); l Use of a magnetic precision attachment to aid retention of the mandibular prosthesis; l Selection of shallow-angled cusped teeth; l Face-bow transfer; l Arrangement of teeth on a semiadjustable articulator to ensure balanced articulation. DISCUSSION Figure 12. Intra-oral view of completed dentures. impression material; Kerr, Romulus, MI, USA), thus avoiding compression of the flabby tissues. Following non-surgical periodontal treatment of the mandibular teeth, and endodontic treatment of the 3|, the 3| was de-coronated

and prepared for a cast post and core. This was fabricated in palladium-cobalt (Figure 9) and cemented in place. Following this, the master impression for the chrome cobalt RPD was made, and fabrication of the RPD continued in the usual manner (Figure 10). At the ‘try-in’ stage, a cobalt samarium magnetic attachment (Dyna Magnetic System, available from Zahn Laboratory – a Henry Schein Company, Gillingham, Kent, UK) was included in the fitting surface of the RPD to seat against the cast post and core on 3| (Figure 11). The maxillary complete denture and mandibular removable partial denture were completed and delivered in the usual manner (Figures 12, 13a, 13b, 14). At subsequent review appointments, the patient reported satisfaction with stability, aesthetics and function of prostheses. In summary, the key points of this 416 The cases described are timely as they demonstrate how the management of poor denture-bearing areas can be accomplished by expanding on the basic principles

of complete denture construction, and without recourse to surgical implant procedures. In the scenarios described, both patients were elderly, had limited bone available for retaining implants, and one patient had a complex medical history. Contemporary opinions warn that treatment outcomes associated with the use of implants in the maxilla may not be as predictable as in the mandible owing to variable bone quality.4 There is considerable variation in opinion in the dental literature as to the most appropriate choice of impression technique for complete dentures.5 When making definitive impressions for complete dentures, it is recommended a b Figure 13. (a) Lateral view of patient’s right-hand side Note even occlusal contacts (b) Lateral view of patient’s left-hand side. Note even occlusal contacts Dental Update – September 2004 R E M OVA B L E P R O S T H O D O N T I C S Figure 14. Completed maxillary denture impression techniques for maxillary complete dentures could

be considered to some degree as ‘mucocompressive’ impressions (i.e using close-fitting custom trays and high viscosity impression materials; the denturebearing area is compressed).7,8 This technique has been regarded as useful in gaining optimal support from the underlying denture-supporting areas.7,8 However, where extensive ‘flabby’ areas are encountered and compressed during impression making, these will tend to ‘recoil’ and dislodge the resulting overlying complete denture when it is not subjected to occlusal loading.8 A number of techniques have been described for making impressions of denture-bearing areas containing both displaceable and non-displaceable tissues, including the use of separate impression materials in a single impression tray;5 use of two separate trays and impression materials which are then related intra-orally;11 and the selective manipulation of the thermoplastic properties of compound impression material.12 In the second clinical report described,

it was decided not to use any of these techniques. As the patient was elderly (70 years old), and had worn his existing prosthesis for some time, it was felt the benefits gained by the use of a specialized impression technique would be negated by the introduction of a new prosthesis that had a new polished surface. Therefore, it was decided to copy the patient’s existing prosthesis – maintaining the polished surface to which he was accustomed – and to perforate the cold cure base over the area of the flabby tissues when recording the master impression. In the case described, this Dental Update – September 2004 technique proved quite effective, as it reduced compressing the anterior mobile tissues, while gaining optimal support in the conventional manner from the posterior non-mobile regions. Some authorities advocate surgical removal of mobile tissues prior to impression making. Neither the patients nor the authors were enthused by this prospect. Such a procedure would lead to

reduction in the depth of the sulcus available for retention and, as one author has noted, while the flabby ridge may provide poor retention for the denture, it may still be better than no ridge at all.3 The authors were also reminded of the principal aim of prosthodontic therapy cited by DeVan, ‘the preservation of what remains, not the meticulous replacement of that which has been lost’.13 Magnetic retention systems, such as the cobalt-samarium Dyna system used in the case described, are useful adjuncts to overdenture therapy. These are indicated where there is a need for more ‘active’ retention than that achieved by simply covering underlying roots; and where the stresses induced by a precision attachment system would damage roots that are already periodontally compromised.14 The use of magnets reduces lateral stresses on the root – by its nature it is ‘self-limiting’ – i.e once the displacing force exceeds the force of attraction, the magnet disengages. Some

disadvantages of the use of a magnetic retention system include an increase in the bulk of the denture surrounding the magnet; there is less bracing imparted to the prosthesis compared with a stud type attachment; and that, over time, the magnet may corrode, or lose its power, and may need to be replaced.14 Two further points bear mentioning from the clinical reports described: first, the use of a well border-moulded selective pressure impression technique overcame the retentive inadequacies of the denture-bearing area without the need for surgical intervention. In a ‘conventional’ completed denture scenario, failure to achieve adequate peripheral seal of a complete denture in terms of both the functional depth and width of the sulcus may result in loss of retention. The significance of adequate border-moulding in the scenarios described, where the amount of denture support available is already compromised, is evident. Proper orientation of the occlusal plane and provision of

proper balancing tooth contacts in excursive movements prevented ‘tipping’ of the denture and loss of the much-sought retention during function. Arranging the teeth on a semi-adjustable articulator and use of shallow-angled prosthetic teeth was particularly effective in achieving this occlusal scheme. An incorrectly oriented occlusal plane will subject the resulting denture to unfavourable forces,1 further destabilizing a denture that is already relying on poor denture-bearing tissues. It also follows that the occlusal scheme for any dentures resting on displaceable tissues should be carefully designed to avoid incorporation of occlusal interferences, the presence of which will negate the retention of the denture. CONCLUSION The cases described demonstrate how a ‘difficult’ denture case can be treated in the dental surgery without resorting to surgically invasive techniques. The cases described have some important points for the clinician: l Recognition of aberrant anatomy of

the denture-bearing areas (e.g ‘flabby ridges’); l Understanding that specialized impression techniques should be considered; l That both retention and stability are essential features for success, e.g incorporation of occlusal interferences will negate any ‘hardearned’ retention; l A magnetic retention system is a useful adjunct where ‘conventional’ retention is not readily available. Appropriate choice of prosthodontic technique, combined with the skill of the practitioner, increases the possibility of the management of the combination syndrome, while also avoiding invasive 419 R E M OVA B L E P R O S T H O D O N T I C S and expensive surgical procedures. 3. ACKNOWLEDGEMENT The authors are indebted to Mr Tim Clark and the staff of the Dentacast of Exeter laboratory (PO Box 21, 18B Cowick Rd, Exeter, EX2 9BE, UK ) for technical support in the cases described. 4. 5. 6. R EFERENCES 1. 2. Carr AB. Single complete dentures opposing natural or restored teeth. In:

Zarb GA, Bolender CL, Carlsson GE, eds. Boucher’s Prosthodontic Treatment for Edentulous Patients 11th edn. St Louis: Mosby, 1997; pp.460–468 Kelly E. Changes caused by a mandibular removable partial denture opposing a maxillary BOOK REVIEW A Clinical Guide to Orthodontics. By D Roberts-Harry and J. Sandy BDJ Books, 2003 (96pp., £3495p/b; £4995h/b) ISBN 0-904588-78-5; 0-904588-81-5. This book is produced from a series of publications by the authors, which previously appeared in the British Dental Journal. It is divided into 12 chapters on what they regard as key subjects in orthodontics. Each chapter is headed with an ‘in brief’ summary of the issues covered, and I found this a useful tool for quick reference. They are also supported by references for further reading. Excellent clinical photographs and illustrations accompany the text throughout the book to explain the topics discussed. The book opens with the question – ABSTRACT HOW DIAGNOSTIC ARE YOUR RADIOGRAPHS?

Reliability of Digital Radiography of Interproximal Dental Caries. E Sanden, A. Koob, S Hassfield, HJ Staehle and P. Eickholz American Journal of Dentistry 2003; 16: 170–176. Although the technique of diagnosing interproximal caries by bitewing radiographs is well-established, 420 7. 8. complete denture. J Prosthet Dent 1972; 27: 210– 215. Carlsson GE. Clinical morbidity and sequelae of treatment with complete dentures. J Prosthet Dent 1998; 79: 17–23. Henry PJ. A review of guidelines for implant rehabilitation of the edentulous maxilla. J Prosthet Dent 2002; 87: 281–288. McCord JF, Grant AA. Impression making Br Dent J 2000; 188: 484–492. The British Society for the Study of Prosthetic Dentistry. Guidelines in Prosthetic and Implant Dentistry. London: Quintessence Publishing Co, 1996. Davis DM. Developing an analogue/substitute for the maxillary denture-bearing area. In: Zarb GA, Bolender CL, Carlsson GE, eds. Boucher’s Prosthodontic Treatment for Edentulous Patients 11

edn. St Louis: Mosby, 1997; pp141–161 Basker RM, Davenport JC. Prosthetic Treatment of the Edentulous Patient 4th edn. Oxford: Blackwell 9. 10. 11. 12. 13. 14. Publishing Co., 2002 Addison PI. Mucostatic impressions J Am Dent Assoc 1944; 31: 941. Fournet SC, Tuller CS. A revolutionary mechanical principle utilised to produce full lower dentures surpassing in stability the best modern upper dentures. J Am Dent Assoc 1936; 23: 1028. Osborne J. Two impression methods for mobile fibrous ridges. Br Dent J 1964; 117: 392–394 Lynch CD, Allen PF. Management of the flabby ridge: re-visiting the principles of complete denture construction. Eur J Prosthet Rest Dent 2003; 11: 176–180. DeVan MM. The nature of the partial denture foundation: Suggestions for its preservation. J Prosthet Dent 1952; 2: 210–218. Basker RM, Harrison A, Ralph JP, Watson CJ. Overdentures in General Dental Practice 3rd edn. London: British Dental Assocation, 1993; pp.60– 61. Who needs orthodontics? Two

chapters then follow, covering the examination of the patient, which supplies the practitioner with enough information to reach a list of treatment aims. Treatment planning is written in a clear and concise manner accompanied by illustrations, which give the reader an insight into the tooth movements to be expected in each scenario. Appliance choice is covered well, and the illustrations here, yet again, provide a clear picture of what one would expect to achieve with each appliance type. I particularly liked the chapter on ‘fact and fantasy in orthodontics’ which summarized some of the controversial subjects within orthodontics that have been a source of much discussion over recent years. Extractions are discussed with reference to specific tooth types, which I thought particularly helpful. Anchorage control, and impacted teeth are well documented, as well as a chapter on the histological nature of tooth movement – a subject of importance, but a little out of place in what is

overall a ‘clinical’ textbook (root resorption is already discussed in brief in the section on ‘risks’). The book closes with an overview of combined treatment, which describes some cases requiring a multi-disciplinary approach. This provides the reader with an idea of what may be involved in the treatment of more complex cases. This book is easy to read, and an excellent source of information for the undergraduate and the general dental practitioner with a special interest in orthodontics. Angharad Brown University Dental Hospital, Cardiff monitoring the progress of such lesions can be difficult due to variations in the radiographic procedure. Furthermore, radiographs may not always show the true extent of the lesion, nor indicate the need for clinical intervention. This study investigated the reproducibility and variability that could be achieved by the digitization of such images in relation to the type of film, tissue scatter and time of exposure. The authors found that,

in general, the use of filters to reduce scatter had a small but insignificant effect on the diagnostic quality of the image. However, careful digital manipulation of the radiographic image resulted in a statistically significant improvement of the validity of the image. This paper is particularly relevant as more and more practitioners make the move to digital radiography. If the images are more consistent, as this paper would suggest, digital manipulation must result in improved diagnosis. Peter Carrotte Glasgow Dental School Dental Update – September 2004