Root canal treatment is needed when an injury or a large cavity damages the nerve of the tooth, found within the root. The nerve becomes infected or inflamed, and can cause discomfort. Symptoms that the pulp has become infected may include sensitivity to hot/cold or sweets, pain, swelling, pain to biting or pressure, and a bad taste in the mouth. In order to salvage the tooth, a root canal is most commonly indicated. When a root canal is performed, the nerve of the tooth is removed and all the canals of the tooth are filled and sealed to prevent bacteria from entering. Afterward, a full coverage crown is fabricated to protect the root canal treated tooth from breaking. General dentists are qualified to perform root canals, but may refer a patient to a specialist if the tooth is particularly complicated or is being treated for the second time.