When a deep cavity or crack causes infection that damages a tooth’s pulp (which contains blood vessels, nerves, and connective tissue), severe pain results. If left untreated, the damage can spread to the surrounding bone, causing further problems. For this reason alone, patients with an infection in the pulp of a tooth need to undergo endodontic treatment that involves drilling to the core of the tooth; removing the damaged pulp; and then cleaning, shaping, filling, and sealing the tooth. A “root canal” procedure derives its name from the fact that the pulp branches down each root through canals that stop just short of the bottom tip of the tooth. Endodontic treatment preserves teeth and circumvents the need to extract them.
P.S. Root canal treatment removes the source of pain caused by an infected pulp; because the procedure is performed with local anesthetic, it does not cause pain.