In order to understand endodontic treatment, it helps to know something about the anatomy of a tooth. Teeth have several layers. The outside layer of the tooth is composed of a hard layer called enamel. Enamel is supported by an inner layer called dentin, which has at its center a soft tissue known as the pulp. The pulp contains blood vessels, nerves, and connective tissue that are responsible for forming the surrounding dentin and enamel during tooth development. The pulp receives its nourishment supply from vessels which enter the end of the root. Although the pulp is important during development of the tooth, it is not necessary for function of the tooth. The tooth continues to be nourished by the tissues surrounding it even after the pulp is removed.