A 'sufficient cause' model for dental caries.

Background: It is generally believed that dental caries is an infectious disease. The occurrence of dental caries is affected by a variety of determinants. In order to estimate the precise extent of the relation between specific determinants and the outcome phenomenon (i.e. the occurrence of dental caries), a coherent disease model is required. This model should also permit multivariate analysis to control for confounders and interactions. Only with such a disease model will it be possible to investigate the relation between the occurrence of a determinant and dental caries, and to estimate the extent of this relation. The known causal models for the explanation of dental caries do not fully meet these requirements.

Method: Rothman's 'sufficient cause' model has been used as a starting point for the development of a new coherent disease model, to explain the occurrence of dental caries and allow multivariate analysis.

Results: The sufficient cause for dental caries comprises three component causes: sufficient microorganisms with cariogenic potential, easily fermentable carbohydrates and teeth. Whether dental caries actually occurs also depends on the influence of independent risk factors that interact with the component causes in a protective, as well as in a risk-increasing manner. These independent risk factors are saliva, fluoride, oral hygiene and diet.

Conclusions: The 'sufficient cause' model for dental caries is a biological model in which distinction between protective and risk-increasing factors has been made, and interaction between factors has been described. With this model, it will now be possible to assess the extent of the relationship between a determinant and dental caries (the outcome phenomenon) using multivariate techniques.