Disorders of the temporo-mandibular joint.

A great number of people (60–70%) have some problem with the temporomandibular joint (TMJ) but most are asymptomatic. About 25% of this group has symptoms that can be attributed to the TMJ. Of this group only 5% will get treatment and these patients are mostly women – they outnumber male patients by at least 4 : 1. Temporomandibular disorders occur at any age but most often in young adults. Pain the temporomandibular area is the most common complaint and is easily related to a lesion of the TMJ. However, the exact cause of TMJ problems is often difficult to determine because several disorders may be present at the same time and combined muscular and inert tissue disorders are not uncommon. As a consequence, it may be necessary to treat both joint and muscle. Conservative treatment is still the most effective management for more than 80% of patients. There are several major causes of TMJ problems: • A single major injury, even if it has been only a light blow to the mandible or extreme stretching of the TMJ, can permanently injure the joint and ligaments. • Repetitive microtraumas, such as clenching, grinding or atypical chewing for a prolonged period of time, may damage the joint and then lead to muscular problems. • Monoarticular arthritis and inflammatory polyarthritis, such as rheumatoid arthritis, but seldom psoriatic arthritis, may affect the joint. • Abnormal biomechanical loading as a result of structural changes of the teeth may also be harmful. However, this should not be overestimated as a cause of TMJ problems. Disorders of the temporomandibular joint are summarized in Table 1.