A hole in a tooth caused by decay. A cavity is caused by the formation of dental plaque (see plaque, dental), which is made up of bacteria, food particles, and saliva. The bacteria interact with sugars in food particles that remain in the mouth and on the teeth to form acid, which dissolves the calcium and phosphate in the enamel of the tooth. This damage to the structure of the tooth is the first stage in the development of a dental cavity. If the cavity is not treated, it can reach the inner structures of the teeth, inflame the pulp of the tooth, and cause persistent pain, especially after consuming foods that are sweet, hot, or cold.