The pulp of a tooth is a soft substance in the centre of a tooth that consists of nerve, blood vessels, and connective tissue. A root canal is the treatment of that pulp that is inflamed, dead, infected. The pulp chamber is the hollow part in the centre of a tooth that, as its name implies, contains the pulp. It continues down canals that extend through to the roots of the teeth and into the surrounding bone. Some roots have more than one canal.
A root canal treatment treats the nerve of the tooth. When the root canal is treated, the pulp of the tooth is removed and all the canals and pulp chamber of the tooth are filled and sealed to prevent bacteria from entering.