Cariogenic Flora: Establishment, Localization, and Transmission

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Abstract
The foregoing is a review of current information on various aspects of the development of the cariogenic flora and it illustrates some of the complexities involved. The multifactorial nature of dental caries makes it necessary to look at this disease in a special way. Etiologic forces represented by a complex bacterial flora and a variable dietary influence are in competition with resistance factors of the host, which include the immune system. This creates a situation where it is difficult to segregate individual aspects of the disease for study. One approach is to design study models that emphasize the factor under investigation in relation to other contributing factors. For example the currently used animal caries test models are deliberately exaggerated in terms of the cariogenic challenge applied. Very young animals are continuously exposed to a high sucrose diet and are infected with a high dosage of cariogenic organisms. The clinical counterpart of this model should use subjects with high caries activity, because it is reasonable to assume that etiologic factors are exaggerated in human populations where the disease is rampant. However, if the purpose is to study resistance factors such as immunity, it may be more profitable to investigate their influence in either animal or human models where the cariogenic challenge is reduced. This, in effect, proportionally increases the influence of a comparatively subtle factor such as immunity. Davies has made a similar point in relation to the influence of hereditary factors in dental caries. He states the belief that regions of low caries prevalence would be the most promising for epidemiological investigation of resistance factors. Investigations into the role of immunity in dental caries have not been too productive in the past. However, it now is possible to focus on selected target organisms and to apply recently acquired information about the immune system operating in the oral cavity. Detailed knowledge of the origins and development of the cariogenic flora and the mechanisms by which it is maintained in individuals and in populations should permit a rational attack on the problem.