Charles F. Shuler, D.M.D., Ph.D.:
Dental caries incidence is affected by host factors that may be related to the structure of dental enamel, the immunologic response to cariogenic bacteria, or the composition of saliva. The specificity of these factors is dependent on the genetic makeup of each individual and the expression of specific genes. It is possible that allelic variation related to a host factor may contribute to increased risks for the development of carious lesions. The present review examined the literature to address the question, Is the risk for dental decay related to patterns of genetic inheritance?
The basic sequence of the human genome is now becoming readily available. The information contained in the genome will provide new approaches to understanding the etiology of human disease and provide new opportunities for diagnosis and management. There have been numerous reports that there is a genetic contribution to the development of dental caries, but there has been no evidence-based analysis of those reports. Establishing a basis for a genetic contribution to dental caries will provide a foundation for future studies of the disease process.
The evidence shows that inherited disorders of tooth development that result in altered enamel structure increase the incidence of dental caries. Dental enamel that is insufficiently mineralized and retains organic components is more susceptible to decay. Patients affected with these syndromes can be readily identified and categorized by well-accepted diagnostic criteria. Such patients are often identified prior to the onset of extensive dental caries on the basis of appearance of the teeth.
Thus, the genetic mutations that are associated with these syndromes provide a link between inheritance and increased susceptibility to dental caries. The specific genetic linkage for all of these syndromes of altered tooth development has not yet been determined. Consequently, it has not been possible to complete genetic screens of large populations to determine whether the same genes/mutations are also associated with increased susceptibility to dental caries in nonsyndromic patients.
Alterations in the immune response to cariogenic bacteria may also increase the incidence of caries. There have been reports of a relationship between human histocompatibility antigen types and an increased incidence of dental caries. At this time the association between specific patterns of HLA genetic inheritance is weak and does not provide a predictable basis for predicting future decay rates. Additional research is required to further examine the contribution of specific HLA types and the risk for dental caries.
Salivary function is critical to maintaining dental enamel mineralization and altering the pathogenicity of cariogenic bacteria. The evidence is strong that xerostomia greatly increases dental caries risk. There is only very weak evidence that xerostomia has a defined genetic basis rather than being the result of some acquired effect that reduces the functioning of the salivary glands. Information on saliva constituents and dental caries is insufficient to make a determination of genetic linkages predisposing to dental caries.
The evidence supporting an inherited susceptibility to dental caries is limited, but information generated from the human genome project should provide a resource for further investigation of the genetic contribution to dental caries. Genetic linkage investigations of well-characterized populations with clearly defined dental caries incidence will be required to further analyze the relationship between inheritance and dental caries.