Genetic Influences on Temporomandibular Joint Development and Growth.

The temporomandibular joint (TMJ) is a small synovial joint at which the mandible articulates with the skull during movements involved in speaking and mastication. However, the secondary cartilage lining its joint surfaces is indicative of a very different developmental history than limb cartilages. This review summarizes our current knowledge of genes that regulate the formation of primary components of the TMJ, as well as genes that regulate postnatal growth of the TMJ. Although the TMJ is regulated by some of the same genes that are important in limb joints, others appear unique to the TMJ or have different actions. Runx2, Sox9, and members of the TGF-β/BMP family are critical drivers of chondrogenesis during condylar cartilage morphogenesis, and Indian hedgehog (Ihh) is important for formation of the articular disc and cavitation. Osterix (Osx) is a critical regulator of endochondral bone formation during postnatal TMJ growth.