Root canal treatment is necessary when the nerve artery and vein of the tooth become exposed, such as when a cavity reaches all the way to the pulp of the tooth. Sometimes deep restorations or trauma to a tooth may cause damage to the nerves, which can also lead to a root canal. Once this occurs the pulp becomes infected, and can lead to an abscess at the roots tip. By the time the pulp is infected it cannot heal on its own; it must be treated by a dentist. Symptoms that the pulp has become infected may include sensitivity to hot/cold or sweets, pain, swelling, pain to biting and pressure, and a bad taste in the mouth. Sometime no symptoms are apparent and the person is unaware of any problem until a checkup.
During a root canal the doctor will clean out the infected pulp and disinfect the canals of the tooth. Once the infection is resolved, the canals are filled to prevent any further infections and then a core build-up and crown are placed to restore and protect the tooth.