If the nerve of your tooth becomes infected by decay, or damaged by trauma, root canal treatment is often the only way to save your tooth. Inside your tooth's hard outer shell of enamel is a nourishing pulp of blood vessels, lymph vessels and nerves. The root canals, which contain the pulp, extend to the bone.
Deep tooth decay, or an injury, can cause serious damage and infection to the pulp's nerves and vessels. A "root canal" (the technical term is endodontic treatment) cleans out the infected pulp chamber and repairs the damage.