It has been established that the oral environment is one of the primary factors in the caries process. Only when acidity increases in the oral environment does demineralization of enamel, and subsequently caries, occur. In this section, the role of fermentable carbohydrates is discussed, paying particular attention to how caries can be influenced by the cariogenic potential of ingested sugars and starches, the physical traits of ingested carbohydrates (such as their adhesiveness), and the frequency of intake and exposure to sugars.

The Stephan curve, which illustrates the dental pH changes over time in response to a carbohydrate challenge, is also introduced, with a discussion of how factors such as the type of carbohydrate, the buffering capacity of saliva, and the type and quantity of bacteria present in plaque affect dental plaque pH responses.