Tooth decay is the disease known as caries or cavities.
Unlike other diseases, however, caries is not life threatening and is highly preventable, though it affects most people to some degree during their lifetime. Natural bacteria live in your mouth and form plaque. The plaque interacts with deposits left on your teeth from sugary and starchy foods to produce acids. These acids damage tooth enamel over time by dissolving, or demineralizing, the mineral structure of teeth, producing tooth decay and weakening the teeth. The acids formed by plaque can be counteracted by simple saliva in your mouth, which acts as a buffer and remineralizing agent.