A broken jaw (or mandible fracture) is a common facial injury. Only the nose is broken more frequently. A broken jaw is the 10th most common fractured bone in the human body. Fractures (breaks in the bone) are generally the result of a direct force or trauma to the jawbone (mandible).
A temporomandibular joint (TMJ) facture occurs when the mandible and/or temporal bone is broken near or through the TMJ, the joint connecting the jaw bone to the skull. Like other bones in the body, the mandible, also known as the jaw bone, and the temporal bone, the bone on the skull that forms the upper part of the jaw joint, can break when subjected to trauma. TMJ fractures occur due to direct trauma to the face. The jaw most often breaks along the condyles, which are rounded projections on the jaw bone. Fracture also may occur with a dislocation of the joints.
Motor vehicle accidents, assault, sports injuries, and falls are the most common causes of TMJ fractures. Men aged 20 to 29 years are most likely to sustain these injuries, and are approximately 3 times more likely than women of the same age to do so.
Following a TMJ fracture, especially if the inside surface of the mouth is torn, there also is a risk of infection, which can lead to osteomyelitis of the jaw. Blows to the head severe enough to cause a TMJ fracture can also cause a concussion.