When decay reaches the pulp or nerve of a tooth or when the nerve itself dies due to a sudden traumatic event or a fracturing or cracking of the teeth, root canals are required. First your  dentistwill remove the pulp from the affected tooth after giving local anesthesia. Then the canals are prepared, irrigated,  filled and sealed with an inert biocompatible material,so that bacteria cannot re-enter the tooth to cause another infection. When the endodontic treatment is complete, the tooth is by no means “dead”. It receives quite adequate support from the surrounding tissues and may be expected to last as long as any other natural tooth.