Dental treatment and dental health. Part 2. An alternative philosophy and some new treatment modalities in operative dentistry A. S . Dawson* 0. F. Makinson?
Key words: Dental health, dental treatment, treatment modalities, operative dentistry. Abstract In this, the second of two papers on the relationships between dental treatment and dental health, the philosophical basis of Minimum Intervention Dentistry is presented. This approach to patient care has several distinct treatment modalities. These range from preventive measures and fissure sealants, through monitoring carious lesions for active progression or arrest, to minimal cavity designs such as tunnel preparations and preventive resin restorations which employ adhesive dental restorative materials. This paper discusses these techniques and the implications of this change in philosophy for dental teaching, research and manpower considerations. (Received for publication August 1989. Revised March 1991. Accepted May 1991.)
Introduction In a previous paper,' Dawson and Makinson posed the question: Does dental treatment necessarily improve dental health? After reviewing some of the literature pertaining to the topic, the authors concluded that dental treatment does not cure caries, and at the very best it merely slows the progress of tooth destruction. In this paper, the authors outline an alternative philosophy and the
*Dental Officer, Royal Australian Air Force. ?Reader in Conservative Dentistry, The University of Adelaide. Australian Dental Journal 1992;37(3):205-10.
treatment modalities that have arisen from the recent reappraisal of practices in operative dentistry. It is important, as a basis of the subsequent discussion, to recognize that: (1) Dental caries is an infection of the dentate mouth. (2) So called dental caries of the teeth is, at least in the initial enamel lesion, but a sign of the infection present in the mouth. (3) This infection remains in the dentate mouth even when all decay has been removed from the teeth. (4) This infection remains as a danger while any teeth are present and there is at this time no treatment available that will eliminate this infection from the individual: merely methods to minimize the dentate symptoms.
A new philosophy If the premise is accepted that dental treatment results in a gradual but inexorable reduction in the amount of sound enamel and dentine comprising an individual's dentition, it must also be accepted that logic must replace the previous idiosyncratic approach to diagnosis and treatment planning in operative dentistry. Consequently, a number of approaches can be combined to achieve a less destructive form of dental treatment. They are: Prevention. Remineralization. Minimal Intervention. Reducing the rate of restoration replacement. 205
Prevention Modern dentistry has achieved much in the understanding and prevention of dental caries. The widespread use of fluorides has had dramatic effects on the incidence of caries in modern westernized countries, but these results do not seem to have had a similar effect on treatment practices.2 Dentistry must now adopt what the report of the Committee of Enquiry into Unnecessary Dentistry3 has termed a ‘preventive philosophy’ with regards to the treatment of caries. Such a philosophy embraces the use of fluorides in the prevention of caries, and in the treatment (arresting) of early lesions. Furthermore, more widespread use of fissure sealants and preventive resin restorations4 is clearly indicated. These preventive therapies are virtually non-invasive, and have been demonstrated to be effective while not having a detrimental effect on the particular teeth being treated. More importantly, the use of these techniques fosters an attitude on the part of the dental practitioner which is preventively orientated, and encourages monitoring of early or slowly progressing lesions. Instead of an attitude of ‘when in doubt, fill’, there must now be a shift towards preventive treatments and monitoring. Remineralization It has been demonstrated,’-’ that by appropriate control of the surface infection (of cariogenic organisms) with fluoride, remineralization may occur. This phenomenon is evident from the rehardening of the carious lesion. The regimen must be carefully and appropriately selected for each patient with regards to the type of fluoride (for example, APF or stannous; solution, mouthwash or gel), its concentration, and the method and frequency of its application. Notwithstanding these considerations, low-dose fluorides have been shown to be beneficial in most situations. Consequently, regular use of fluoride dentifrices, especially when patients are instructed not to rinse after brushing their teeth so as to prolong the effect of the fluoride, are of great use in most situations involving patients at moderate risk of caries. However, care shold be exercised before this procedure is adopted by young children during the period of amelogenesis. Minimizing intervention and restoration replacement The concept of reducing the amount of treatment given to individuals, by modifying the criteria for placement and replacement of restorations, is one of the cornerstones of the ‘New Operative Dentistry’. These criteria in combination with new, 206
minimally-invasive cavity designs using adhesive restorative systems, aim to conserve tooth structure in a population which is now remaining dentate well into old age. During October 1987, a symposium on the topic of ‘Criteria for Placement and Replacement of Dental Restorations’ was held in the United States of America. This symposium discussed all aspects of this topic, from the effects of dental education on dental practice, to new techniques and philosophies in restorative dentistry. In a paper presented at this symposium, Boyds questioned the traditional attitudes on replacement of amalgam restorations, and discussed the effect that undergraduate teaching in dental schools had on a dentist’s practising philosophy. In her conclusion, Boyd stated that dental curricula should not be anchored in the past, but should be oriented towards the future. Most dental practitioners maintain the treatment philosophies developed during their training for their entire practising life. Thus, new techniques and attitudes must be encouraged, so that operative dentistry is no longer based entirely on the principles of dental practice enumerated by Black9 at the turn of the century. This symposium resulted in a series of conclusions and recommendations regarding restorative dentistry.’O As a basic principle, the symposium adopted the conservation of tooth structure as being of prime importance, and outlined criteria for placement and replacement of restorations that were in line with recent philosophies in this area of dental practice. These criteria are paraphrased below. Criteria for the placement of restorations (1) Preventive advice and therapies should be used in an attempt to shift individuals assessed as being at high risk of carious attack to lower risk categories. (2) Operative procedures are indicated if: (a) coronal lesions extend well into dentine, and can be demonstrated to be active; (b) there are pulpal symptoms; (c) there is impairment of occlusion or hnction due to improper contour or other inadequacy; (d) periodontal health is adversely affected; and (e) the appearance of the lesion is unacceptable to the patient. (3) The use of fissure sealants or preventive resin restorations4 is preferable in early, active pit and fissure lesions, or in sites where the presence of a lesion is in doubt, or in cases where the activity of the lesion is questionable. Australian Dental Journal 1992;37:3.
(4) Smooth surface lesions that have not penetrated into dentine should be treated preventively and monitored, rather than restored. (5) Where a restoration is indicated, the position, shape and size of the resultant cavity preparation should be based largely on the extent of the carious lesion, and not on traditional principles.
Criteria for the replacement of restorations (1) If a patient has problems associated with a marginal gap, it will usually be appropriate to replace the restoration. However, the presence of a marginal gap alone is not a criterion for restoration replacement. (2) A restoration should be replaced when secondary caries at the margins of the restoration extends to dentine and is judged as being active. Attempts should also be made to move the patient into a lower risk group through preventive therapies. (3) Restorations that have been assessed as failed or defective, and are associated with a significant loss of function, tissue inflammation, or pulpal pathology should be adjusted, repaired or replaced. Surface deficiencies alone do not constitute an adequate reason for replacement. (4) Restorations which appear to have caused a severe allergic response should be replaced with a suitable alternative restorative material. Milder effects should be monitored, and appropriate specialist consultations may be required. (5) When a patient requests the replacement of a restoration which has caused undue psychological stress as a result of poor aesthetics, inadequate function, or actual or perceived biological hazards, the restoration should only be replaced after the advantages and deficiencies of the alternative treatment have been hlly explained to, and accepted and understood by, the patient. These criteria have the potential to change the day-to-day practice of dentistry in modern industrialized societies, changing the emphasis from the general, automatic surgical treatment of doubtful lesions or restorations, to a more problem-solving approach to treatment planning. Prevention is stressed, as is the need for conservatism in cavity preparation. Restorations should only be placed where there is demonstrable active pathology, and then only minimal intervention is advocated. Existing restorations, if they are significantly defective, should be refinished, repaired or, as a last resort, replaced. Such changes are the result of adaptations to the changes in the presentation of the diseases that operative dentistry aims to treat. Black‘s principles, which were empirically determined for the AmeriAustralian Dental Journal 1992373.
can population at the end of the last century, need to be re-interpreted in modern times. For example, in conserving dentine and caring for the pulp it is worth reconsidering the Massler” method of removing the ‘infected’ carious dentine layer and retaining and remineralizing the stained ‘affected‘ (sterile, demineralized) dentine. Thus, the dental profession must be prepared to abandon dogma and to keep in step with the changing needs in care.
Alternate treatment modalities Caries risk assessment The likelihood of an individual developing progressive carious lesions is dependent on many factors, for example: diet, oral microflora, degree of enamel mineralization, the buffering ability of the saliva, and the morphology of the teeth. Ideally, an assessment of caries susceptibility is an integral part of the treatment planning process. In the past, clinicians have based their judgment of this risk on factors such as the patient’s past caries activity. A FCdkration Dentaire Internationale Working Group’’ has reviewed current methods of identifying high caries risk groups and individuals, and noted that methods of making this assessment should be simple, inexpensive and rapid, and should accurately identify individuals who will develop caries and exclude those who will remain healthy. In addition they stated that, of the specific tests available, the mutans streptococci and lactobacillus assays, and the measurement of salivary buffering capacity, were the most valuable. All of the tests discussed, however, had problems in satisfying the criteria outlined above. The report went on to state that combinations of tests were likely to be the most effective system of identifying ‘at risk’ patients, and that for individual patients ‘the subjective clinical judgment of the dentist, based on a broad knowledge of the risk factors and of the patient, is likely to remain an important factor in the assessment of caries risk.’ Consequently, clinicians should consider augmenting their traditional judgments regarding caries susceptibility with reliable riskpredicting tests when these tests become readily available. Monitoring Operative dentistry has for many years adhered to the tenet that a restoration is the best treatment for a carious tooth. This has been practically interpreted in the axiom: when in doubt: fill. In the light of the findings of the Committee of Enquiry into Unnecessary Dental TreatmentY3the outcomes of the International Symposium on Criteria for the Placement and Replacement of Dental Restorations,’O and the documented ability to arrest or 207
remineralize carious lesion^,^-^ such a belief can no longer be supported. Thus, the activity of lesions must be determined prior to initiating invasive treatment. Embodied in the new approaches to treating carious lesions is the differentiation between smooth surface caries and pit and fissure caries. Fissure sealants, which will be discussed later, have been advocated as the preventive treatment of choice for pit and fissure lesions. Elderton13 has proposed an alternative approach to the axiom outlined above, based on patient education, preventive treatments, and monitoring doubtful lesions. The main aim of this approach is to arrest smooth surface lesions using the following method: (1) Record the site of the lesion. (2) Demonstrate the position of the lesion to the patient, using mirrors if necessary. (3) Institute a general preventive programme (diet, oral hygiene and fluoride usage) and any specific procedures deemed necessary for the particular lesion. (4) Ensure that patients understand that restorations can be avoided, but that the success of this approach lies in their own hands, for it is they who will practise the preventive programmes prescribed. (5) Arrange to review the lesion at an appropriate time, and to reinforce the preventive regime or restore the lesion if it is progressive. Ultimately, such a programme shifts the philosophical emphasis from the previously presented axiom to that of: when in doubt: institute preventive measures and monitor. Fissure sealing Occlusal pits and fissures have been implicated as high caries risk areas by both epidemiologicalstudies and clinical experience. As a consequence of this, acid-etch-retained resin fissure sealants have been studied by a number of i n ~ e s t i g a t o r ssearching ~~-~~ for a cost-effective and reliable measure to prevent fissure caries. These studies, using several different systems and methodologies, revealed varying degrees of success (between 28 per cent and 100 per cent) over periods of up to seven years. Two recent r e p ~ r t s , however, ~ ~ ~ ' ~ have shown 10 year success rates of 94.3 per cent and 84.4per cent, respectively. In his paper, S i m o n ~ e n 'concluded ~ that fissure sealants were safe and reliable, and were more costeffective than traditional methods over the 10 years of his study. Sealants have also been found to be effective therapies for carious lesions associated with pits and fissures. Mertz-Fairhurst and co-workerszonoted that intact sealants reduced the viable bacterial flora 208
in these lesions to a level that could not support active caries. The carious material takes on the appearance of arrested caries, and some remineralization of carious dentine may occur. Thus, fissure sealants are safe to use in cases where caries is suspected but does not warrant more extensive treatment. The American Dental Association,z1 and the British Dental Association and the Department of Health and Social Security,zzhave supported the use of fissure sealants as a preventive measure. The BDAlDHSS working party also preferred sealants as an alternative to amalgam fillings for the treatment of questionable or early carious lesions in pits and fissures. If caries was present, they recommended that it should be removed and the lesion restored with a glass-ionomer material, which could then be etched and included in a resin sealant, much along the lines described by Simonsen4 as a preventive resin restoration. In this latter technique, composite resin is advocated in lieu of the glass-ionomer cement. Glass-ionomer cement materials have also been recommended for use as fissure sealants. McLean and Wilsonz3 noted that these materials were not successful when used in fissures without a patent orifice, as the sealants were soon lost. However, when used in patent fissures, these materials were very successful: probably due to their adhesive properties and their ability to slowly release fluoride into surrounding tooth structure. Consequently, McLean and Wilson have suggested that a technique, where the fissures are widened very slightly using a fine diamond bur, may be ofuse as an adjunct to the use of glass-ionomer cements as fissure sealants. Treatment of approximal caries A number of alternatives have been suggested to the traditional Class I1 cavity preparation described by Black.' Much of this re-evaluation was centred on the ideal of extension for prevention, and the consequent involvement of otherwise sound occlusal surfaces. M a r k l e ~ , 2in~ 1951, was one of the first workers to propose an alternate cavity design that did not involve the occlusal fissure system. More recently, a number of authors have advocated alternate access routes for treating approximal lesions: these alternatives all attempt to retain marginal ridges to preserve the strength of the tooth. McLeanzs has suggested that these lesions could be treated with glass-ionomer cement materials, using either a buccal or a lingual approach, or where possible direct access, and Knightz6 and Huntz7have described a 'tunnel preparation' which gains access through the occlusal fossa, leaving the marginal ridge intact. Wilson and Australian Dental Journal 1992;37:3.
McLeanZ8have hrther characterized this technique as the ‘internal occlusal fossa preparation’. This method relies on there being sufficient marginal ridge for strength. Consequently, if the ridge is cracked, or undermined to the extent that less than 2 millimetres of enamel remains occlusally or approximally, this technique is contraindicated, and another preparation, such as that described by Markley should be used. Additionally, where the restoration will be subjected to load, a metal reinforced cermet-ionomer is indicated, and if required, this may be overlaid with amalgam or resin. With all of these preparations, the size of the restoration should be determined primarily by the extent of caries, and the cavity design should not include sharp internal line angles.
Implications for dental schools and for the future Each of us will go into old age with a particular amount of dentine. The extent of that remaining tooth structure will primarily depend on the number of treated initial carious sites (or bridge retainer sites), and how often these restorations are replaced. Black-style dentistry cannot increase this store of dentine, only decrease it. It is, therefore, pertinent to consider, for example, if one should promote traditional crown and bridge treatment when partial dentures or adhesive prostheses might suffice. The widespread adoption of these philosophies and techniques is reliant on many factors. Dental schools need to change their curricula to encompass this new ideology and to reflect the realities of practice. They must employ suitable teachers to train students in these new treatment modalities, and clinical teaching must give credit for prevention and overall patient care rather than excessively promoting skills in ‘tooth carpentry’. Within dental schools, the management of dental-care teaching needs to revert to teachers of operative dentistry in larger, integrated restorative dentistry units: this implies a degree of control over fmed prosthodontics and gnathology to limit dentine destruction. Additionally, there is a need for research into the delivery of dental care, adhesive restorative systems, and the longevity and modes of failure of all restorative materials. Finally, there is a need for all dentists to actively reassess their own diagnostic and treatment planning criteria, review treatment failures in their own practices, and strenuously maintain their knowledge of new techniques through ongoing postgraduate education. Meanwhile, dental practices must remain viable, subject as they are to the seemingly endless restricAustralian Dental Journal 1992;37:3
tions imposed by government and the pressures exerted by the current difficult economic climate. Dental schools now need to teach and research the micro-economics of our cottage industry for the benefit of both patient and practitioner, and the profession must actively work with universities and governments to control the dentist to population ratio. For example, dentists in the Netherlands are being paid to move into other forms of employment as a means of countering the oversupply of dentists in that country. Additionally, the current system of remuneration in private-sector dentistry must be reassessed, shifting the emphasis from the surgical treatment of caries to one more akin to that of the physician in medicine. Without such changes in our predominantly private-practice-based system of delivering dental care, it will be virtually impossible to avoid perpetuating the status quo. Indeed, the balance in the market place between minimum intervention dentistry and the traditional restorative care system is very much dependent on the micro-economics of dental care delivery. Consequently, dental schools need to: (1) Train students to present preventive dentistry in a counselling mode which is ’user friendly’ rather than didactic, thus working to change the general public’s perception of what dental care involves. (2) Research how dental practices can change to the new operative dentistry in an economically viable manner. This should now be funded by the profession through national associations together with government health commissions. This latter function probably will require the secondment or appointment of economists to the teaching and research staffs of our dental schools. Conclusion In a previous paper,’ the authors presented arguments in support of a change in the philosophical basis of operative dentistry. It is apparent from this discussion that dental restorations are but a poor substitute for sound teeth. Such restorations will eventually fail, resulting in a continual cycle of replacement leading to larger and more complex treatments. Restorative dentistry, at best, maintains a level of health that lies somewhere between a sound, unrestored dentition and one that is totally destroyed by disease. In fact, traditional dentistry can only be seen as successful if the treatment provided slows the loss of teeth to a rate that is acceptable to the patient, or allows retention of the dentition until the death of the individual. This paper has outlined a philosophy of Minimal Intervention Dentistry and has reviewed some of the alternative techniques available to clinicians. In 209
the light of the modern understanding ofcaries, and the development of adhesive restorative systems, operative dentistry can no longer cling to principles and traditions that were empirically determined at the turn of the century in circumstances greatly different from our modern experience. Our philosophies and treatment methods must continue to evolve, along with our understanding of the diseases we aim to treat and the new adhesive technologies that we can adopt to our requirements.
References 1. Dawson AS, Makinson OF. Dental treatment and dental health. Part 1: a review of studies in support of a philosophy of Minimum Intervention Dentistry. Aust Dent J 1992~37: 125-32. 2. Boyd MA, Richardson AS. Frequency of amalgam replacement in general dental practice. J Can Dent Assoc 198531:763-5. 3. Schanchieff SG, Shovelton DS, Toulmin JK. Report of the Committee of Enquiry into Unnecessary Dental Treatment. London: Her Majesty’s Stationery Office 1986. 4. Simonsen RJ. Conservation of tooth structure in restorative dentistry. Quintessence Int 1985; 16: 15-24. 5. Wei SHY, Kaqueler JC, Massler M. Remineralization of carious dentine. J Dent Res 1968;47:381-91. 6. Silverstone LM, Hicks MJ, Featherstone MJ. Dynamic factors affecting lesion initiation and progression in human dental enamel. Quintessence Int 1988;19:683-711. 7. Johansen E, Papas A, Fong W, Olsen TO. Remineralization of carious lesions in elderly patients. Geriodontics 1987;3:47-50. 8. Boyd MA. Amalgam replacement: are decisions based on fact or tradition? In: Anusavice KJ, ed. Quality evaluation of dental restorations. Chicago: Quintessence, 1989. 9. Black GV. A work on operative dentistry. Vol. 2. Chicago: Medical-Dental Publishing, 1908. 10. Criteria for the placement and replacement of dental restorations. Recommendationsfrom an international Symposium, Florida, 19-21 October 1987 (supp. USNIDR). Aust Dent J 1988;33:338-40. 11. Massler M . Control of caries: a new concept. NZ Dent J 1962:58:69-73. 12. FCdCration Dentaire Internationale. Review of methods of identification ofhigh caries risk groups and individuals. FDI Technical Report No. 31. Int Dent J 1988;38:177-89. 13. Eldenon RJ. Restorations without conventional cavity preparations. Ibid: 112-8.
14. Bojanini JN, Graces HM, McCune RJ, Pineda AR. Effectiveness ofpit and fissure sealants in the prevention ofcaries. J Prev Dent 1976;23:31-4. 15. Mertz-Fairhurst EJ, Della-Giustina VE, Brooks JD, Williams JE, Fairhurst CW. Compariative study oftwo pit and fissure sealants: results after 4% years in Augusta. J Am Dent Assoc 1981;103:235-8. 16. Mertz-Fairhurst EJ, Fairhurst CW, Williams JE, DellaGiustina VE, Brooks JD. Comparative study of two pit and fissure sealants: 7 year results in Augusta. J Am Dent Assoc 1984;109:252-5. 17. Raadal M, Laereid 0, Laereid KV, Hveem H, Korgaard EK, Wangen K. Fissure sealing of permanent first molars in children receiving a high standard of prophylactic care. Community Dent Oral Epidemiol 1984;12:65-8. 18. Wendt L, Koch G. Fissure sealants in permanent first molars after 10 years. Swed Dent J 1988;12:181-5. 19. Simonsen RJ. Retention and effectiveness of a single application of white sealant after 10 years. J Am Dent Assoc 1987;11 5 ~1-6. 3 20. Mertz-Fairhurst EJ, Schuster GS, Fairhurst CW. Arresting caries by sealants: results of a clinical study. J Am Dent Assoc 1986;112: 194-7. 21. American Dental Association Council on Dental Materials, Instruments, and Equipment. Pit and fissure sealants. J Am Dent Assoc 1983;107:465. 22. British Dental AssociationlDepartment of Health and Social Security Working Party. Fissure Sealants: Report ofthe joint BDAlDHSS working party. Br Dent J 1986;161:343. 23. McLean JW, Wilson AD. Fissure sealing and filling with an adhesive glass ionomer cement. Br Dent J 1974;136:269-76. 24. Markley MR. Restorations of silver amalgam. J Am Dent ASSOC1951;43: 133-46. 25. McLean JW. Aesthetics in restorative dentistry: the challenge for the future. Br Dent J 1980;149:368-73. 26. Knight GM. The use of adhesive materials in the conservative restoration of selected posterior teeth. Aust Dent J 1984;29:324-3 1. 27. Hunt PR. A modified Class I1 cavity preparation for glass ionomer restorative materials. Quintessence Int 1984;15: 1011-8. 28. Wilson AD, McLean JW. Glass-ionomer cement. Berlin: Quintessenz, 1988.
Address for correspondenceheprints: 0 . F. Makinson, Department of Dentistry, The University of Adelaide, GPO Box 498, Adelaide, South Australia, 500 1.
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