Complex squamous epithelium; surface keratinization or incomplete keratinization; epithelial nail processes are numerous and slender. Basal cells grow actively, occasionally melanocytes, or melanin particles, and pigmentation at the base. Therefore, the gums are sometimes black

Covering the gingival sulcus wall; layered squamous epithelium with epithelial nail process. There is a clear boundary from the binding epithelium.

Akeratosis: Inflammation of connective tissue. Can't resist mechanical forces and easily break.

The squamous epithelium extends from the base of the gingival sulcus to the enamel cementum boundary and attaches to the surface of the tooth; there is no keratosis and no epithelial nail process, but epithelial nail process can be seen if stimulated.

Immature, low differentiation, simple epithelium

Thin keratinous epithelium; with epithelial nail process.

1. Gingival dental group Direction: Cephalogen of the dental neck, free gingival and attached gingival layer propria Features: The most common group of gum fibers Function: Pull the gums into tight bonds with the teeth

2. Alveolar gingival group Direction: Alveolar ridge Free gingival and attached gingival layer propria Function: Stable gums and alveolar bones

3. Ring group Direction: Around the neck of the teeth, arranged in an annular shape Features: thinner than other groups, often wrapped with adjacent fiber bundles Function: Helps free gingival adhere to teeth

4. Periosteum group Direction: From the cementum of the neck of the tooth, it passes through the lateral periosteum of the alveolar process, enters the alveolar process, vestibular muscle and the bottom of the mouth, and exists on the lip and tongue side.

5. Cross the group Direction: The cementum of the self-bound epithelial root square, spans the alveolar septum, and ends at the same position in the adjacent teeth. Features: Only exist on the adjacent tooth. Function: Keep the two adjacent teeth in contact and prevent separation