Teeth are composed of, and held in place by, several different structures.
The crown of the tooth is the visible part of the tooth that is not normally covered by gingiva (gum tissue). It is covered by enamel (blue).
The root is the part of the tooth that is normally imbedded in the jaw. It is covered by cementum (heavy brown line), rather than enamel. The root is anchored in the alveolar bone (tan) by the periodontal ligament (fine brown lines).
The gingiva (dark red) is a thick, gasket-like structure that surrounds each tooth; it is attached to the tooth by junctional epithelium (orange). There is a very small wedge-shaped space between the enamel and the gingiva with junctional epithelium at the base, called the gingival sulcus. The oral mucosa (pink) refers to the entire lining of the mouth. It does not include the gingiva.
The pulp canal is a tunnel-like structure running longitudinally down the center of the tooth. It contains the pulp, which is the tooth’s blood vessel (red) and nerve (yellow).
The structure of the tooth is made of dentin (fine orange lines), a bone-like tissue produced by cells called odontoblasts. Dentin is arranged in tubules that radiate out from the pulp canal.