When a tooth becomes badly infected, it can only be saved by a root canal procedure that involves removal of the nerve and pulp inside the tooth. This “endodontic treatment” is preceded by injections of local anesthetic, after which an opening is created in the tooth’s crown and into the pulp chamber. After the pulp is removed, the chamber is cleansed and enlarged. Then, a temporary filling is set into the tooth’s crown. On the next visit, the temporary filling is removed and the root canals are filled with special rubber-like material and permanently sealed. Again, a temporary filling is set in place, which is subsequently removed when a crown is placed on the restored tooth.
P.S. Because a tooth’s nerve serves no other purpose than to provide the sensation of hot or cold after the tooth has emerged through the gums, its removal with root canal treatment alters neither the tooth’s health nor its function.