When the bacteria in dental plaque digest sugars, they produce substances which then attack the enamel and dentine, causing tooth decay. The higher the concentration of sugar in the saliva and on the surface of the teeth, the more acid substances are produced.

Sugary foods, including sweets, are therefore factors that promote tooth decay. As sweets tend to stick to the teeth and their sugars are eliminated more slowly by the flow of saliva, they constitute a significant risk factor for tooth decay.