Caries is an infectious disease of the teeth caused by the destruction of tooth tissue. The destruction is caused by bacteria that reside in the oral cavity. They feed on sugars from the food and drinks you consume, while producing acids in the process. The strongest protective layer of the teeth, enamel, is degraded by the acids produced as a byproduct of bacterial metabolism. Acids introduced into the oral cavity through beverages and food can also damage the enamel coating.