Dental cavities, also known as dental caries or tooth decay, are areas of erosion on teeth, usually a result of decay caused by acid-producing bacteria. In the beginning stage of cavity formation, erosion is limited to the enamel, the outer layer of the tooth. From this point, erosion can continue until it reaches to the next layer of the tooth, known as dentin. Dentin is close to nerves, so a cavity that reaches dentin can make the tooth sensitive to cold drinks, touch, and other sensations. At the final stage, the cavity progresses beyond the enamel and dentin and into the pulp, the innermost layer of the tooth. At this point, a person will often experience pain in the form of a toothache and will likely need either a root canal or tooth extraction.

The stages of a cavity