Gomphoses

Gomphosis is a type of fibrous joint in which a conical peg fits into a bony socket in the maxilla or mandible. This peg-in-socket arrangement binds the tooth to the jaw and is classified as a synarthrosis, or immovable joint, though minute physiologic movement can occur during function and growth.

Anatomy: The tooth root is covered by cementum; the socket is formed by the alveolar bone of the jaw. The tooth is anchored in place by the periodontal ligament, a dense fibrous connective tissue that extends from the cementum to the alveolar bone. The ligament contains Sharpey's fibers that insert into both tissues, helping to absorb occlusal forces and allow a small amount of tooth mobility during chewing and eruption. The cementum and alveolar bone are dynamic and can remodel in response to stress.

Development and clinical relevance: Gomphoses form as teeth erupt and become anchored in the socket. The integrity of the periodontal ligament is essential for tooth stability; periodontal disease can degrade this ligament and lead to tooth loosening or loss. In evolutionary and functional terms, gomphoses provide strong anchorage while permitting slight tooth movement during mastication and growth but without forming a true synovial joint.

Comparison: Unlike sutures, which join skull bones, and syndesmoses, which connect long bones by ligaments, gomphoses are unique to the dental system and do not permit significant motion.