After eating, food particles and liquids that contain sugars and starches are left behind on the teeth. Bacteria that also exist in the mouth combines with the left-over substances and forms acids. The acid can eventually destroy the protective enamel covering on the teeth (as well as the dentin layer which is below the enamel), causing holes or cavities, called tooth decay or caries. Tooth decay can lead to infection, causing pain and inflammation. Beneath the enamel and dentin of the tooth is the dental pulp, soft tissue that contains nerves, blood vessels, and connective tissue. Dental pulp extends from the crown of the tooth to the root. If decay from cavities reaches the dental pulp, a root canal is required. During root canal, the tooth and area around the tooth are anesthetized. A hole is then drilled into the tooth and the pulp tissue is removed from the tooth. The canals are then cleaned and filled with medicine. A permanent seal, or crown, is put in place over the tooth. There are several potential complications associated with this procedure that should be discussed with a doctor prior to surgery.