What exactly is a root canal? The visible white part of the tooth is called crown, and it is surrounded by the pink colored gum. Beneath the crown and gums runs the root canal. It extends from the tip of the tooth and then down. This canal encloses the pulp, that is made up of soft tissues, nerves and blood vessels. Treatment is needed when the pulp gets infected. The treatment removes the infected part, and thus also prevents its spread.