What is the outer surface of the root called?

The outer surface of the root of a tooth is indeed called cementum. Cementum is a mineralized tissue that covers the roots of teeth and serves several important functions. It helps anchor teeth within the jaw by providing a surface for periodontal ligaments to attach, thereby supporting the overall structure of the tooth. Cementum is less hard than enamel, which covers the crown of the tooth, and it can continue to grow throughout the life of the tooth, repairing and maintaining the connection between the tooth root and the surrounding bone.

Dentin, while also a significant component of the tooth structure, is found beneath the enamel and cementum and makes up the majority of the tooth's bulk. It is not the outer layer of the root. Enamel, on the other hand, is the hard outer covering of the crown and is not present on the root surface. The pulp is the innermost part of the tooth, containing nerves and blood vessels, and is located in the center, not on the outer surface. This understanding of tooth anatomy emphasizes the essential role of cementum in dental health and structural integrity.