The document describes the anatomical structure of teeth. Teeth have several parts - the root embedded in the jaw, the crown visible in the mouth, enamel forming the hard outer layer, dentine forming the bulk, pulp containing blood and nerves, and cementum covering the root. Surrounding structures include the periodontal ligament attaching the tooth to bone, oral mucosa lining the mouth, gingivae protecting the bone and roots, and nerves and blood vessels supplying the tooth. Cavities are holes that grow over time in the enamel and dentine if not repaired. Cavities are classified depending on their location such as in fissures, between teeth, or near the gums.