Many factors play a role in the development of cavities. Here’s how it works: Bacteria in your mouth feed on sugary, starchy foods and drinks (fruit, candy, bread, cereal, sodas, juice and milk). The bacteria convert these carbohydrates into acids. Bacteria, acid, food and saliva mix to form dental plaque. This sticky substance coats your teeth. Without proper brushing and flossing, acids in plaque dissolve tooth enamel, creating cavities, or holes, in the enamel surface.