Root canals or endodontic treatment are necessary to save a tooth with a diseased pulp or nerve. When the pulp or nerve of a tooth is injured or diseased, the tissue dies. If it is not removed, the tooth will often become painfully infected. Without timely treatment, you risk the possibility of losing the tooth. When a root canal is performed, the dentist removes the diseased tissue and it is sealed off, and finished with a crown to stabilize the tooth.