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