Microscopic Anatomy of the Healthy Gingival Unit (Histology)

The attached gingiva and free gingiva share similar histology because both are considered masticatory mucosa (due to its rubbery surface texture and resiliency).². Because the free gingiva and attached gingiva protect the underlying periodontium, the epithelium is mainly keratinized. The cells that make up the free gingiva and attached gingiva are described as keratinized stratified squamous epithelium. However, there is a small area of nonkeratinized stratified squamous epithelium in the sulcus at the col area. The alveolar mucosa is also made of nonkeratinized stratified squamous epithelium (which is the most common type of epithelium in the oral cavity).².

All forms of epithelium have an adjoining connective tissue located deep to the basement membrane; in the case of the oral mucosa, this connective tissue is considered the lamina propria.². The main fiber group of the lamina propria is collagen fibers, which provide the firm attachment of gingiva to cementum and alveolar bone. The lamina propria also contains the vascular supply for the gingiva.