Dental caries (caries – from the Latin, decay), which simply means decay or rotting of the teeth, is a form of progressive destruction of enamel, dentine and cementum initiated by microbial activity at the tooth surface. Loss of tooth substance is characteristically preceded by a softening of these tissues, brought about by partial dissolution of mineral (Silverstone, Johnson, Hardie and Williams, 1981). Thus, dental caries can be distinguished from other destructive processes that affect the crowns of teeth, dealt with in Chapter 20, such as attrition and abrasion due to mechanical wear and erosion due to chemical causes, in which as far as is known bacteria play no part.

Dental caries has been the subject of intensive study, epidemiologically and in the laboratory, because it is so common in man, particularly man living under the highly-organized social and dietary conditions that have been characteristic over the past 150 years of what is called western civilization. Most of what is known about dental caries derives either from the direct study of the human state or from experiments on animals in which various aspects of the human condition are simulated. The study of the natural disease in animals is limited to description and recording the prevalence. Clearly, however, much of the experimental work is relevant to the natural disease in animals, particularly to that in the same species.

It is appropriate here only to summarize current views of the process that gives rise to dental caries in man. It seems reasonable to extrapolate this to animals, though with the same caution that should be exercised when extrapolating to people observations made on disease in animals.