The present status of caries research

Abstract This article attempts to interpret fundamental caries research in terms of the clinical application to man. A brief survey has been made of the development of various concepts of the etiology of caries in man since the time of W. D. Miller. It is suggested that the prevalence of caries in any single individual may be interpreted as a composite of several modifying influences resulting from genetic, developmental, endocrine, and salivary factors, as well as from oral microorganisms and oral food debris. Because of overlapping of these several influences in each individual patient, an effort should be made to establish which one of these factors may be more prominent in its effect than others. In terms of practical means of prevention, three approaches have been discussed: environmental, developmental, and biochemical. 1.1. Investigations in laboratory animals and in human beings indicate that if the teeth are susceptible to caries, and the teeth of modern man usually are, it is advisable to cut down on the in-between meal consumption of highly sweetened substances, which, in addition to their high sugar content, have a tendency to cling to the teeth and be retained in the mouth for prolonged periods of time. Specific evidence from studies in humans is unfortunately limited to only a few types of sweets. As far as the oral environment is concerned, it appears that only under unusual circumstances has it been possible to influence significantly the metabolism and growth of the oral microorganisms. Studies on oral clearance of various forms of sugar may serve as an index of their caries potentiality until more precise information is available. A simple test for individual variations in the ability to evacuate the mouth merits further study. Also, more attention should be given to oral debris of endogenous origin (fever coating). 2.2. An important facet of the caries problem can be scrutinized and remedied only by going back into the early dietary history of the patient during the period of tooth development. This concept is strengthened by observations on fluoridation which show that the beneficial effect is greatly increased the further back in the developmental history of the individual one goes in starting this dietary supplement. It is thought that the greatest hope for remedying this disease on a large scale in future generations lies in the initiation of preventive procedures which will strengthen the resistance of the teeth themselves to caries. 3.3. The biochemical approach to caries prevention has the advantage that it is immediately applicable in private practice to the extent that our knowledge at any time permits. It is an approach which accepts the existence of all factors which at the moment are thought to favor caries production, namely, the microorganisms, the carbohydrate food substrate, the acid and enzymes, and the inadequately developed teeth. Under these circumstances, this approach should endeavor, first, to block whatever defective pathways to caries already exist in the teeth and, second, to interfere intelligently with whatever initial biochemical changes occur in caries prior to cavity formation. At the moment, the topical application of heavy metals such as silver nitrate and the application of fluorides to tie up with the organic and inorganic components, respectively, are the principal substances at hand. An intensive effort should be made to study further the exact physiologic potentialities of the enamel, its permeability, its ionic exchange with the saliva, and its incipient chemical alterations in the initial caries process. From such studies may come preventive procedures which could be used to the benefit of our individual patient, young and old alike. To explore the basis for individual variations in caries prevalence, projecting the prognosis and planning preventive measures, will require as complete information as possible on each patient. It would be desirable to explore the family history of a patient's parents and other relatives; the dietary history of the patient with respect to early life, geographical and national origin, food hibits, and economics; the history of previous illnesses; the patient's salivary gland function, hormone balance, etc. In addition to the conventional tests of bacterial flora and carbohydrates in the oral cavity, one would wish to appraise the individual patient's capacity for clearing the mouth, and the relative viscosity, sedimentation rate, and flow of saliva. Simple clinical tests for this purpose would be of practical value.