Conditions that can affect the TMJ

Muscle disorders

Disorders of the muscles surrounding the TMJ (the muscles of mastication) are described on the original site as the most common cause of TMD. They can involve pain, altered muscle function and restricted jaw movement. Trauma, excessive or unaccustomed use of the chewing muscles, excessive opening, stress, illness and viral infections may influence muscle function.

Temporomandibular joint disorders

Functional TMJ disorders are common and may sometimes be present as joint noises without pain. The original site groups them into three broad categories:

• Derangements of the articular disc.
• Structural problems affecting the joint surfaces.
• Inflammatory joint disorders.

Articular disc derangement

A change in the disc’s attachment to the mandibular condyle can affect how the joint moves. With disc displacement with reduction, the disc may sit forward and the condyle can move back underneath it as the mouth opens, often producing a click. With disc displacement without reduction, the disc cannot return to its usual position and mouth opening may be limited.

Joint surface problems

In a healthy joint, the surfaces move over one another with very little friction and are lubricated by synovial fluid. Changes to the disc, cartilage or joint lubrication can affect the joint surfaces; the original site gives osteoarthritis as an example.

Inflammatory joint disorders

Inflammatory disorders can affect joint structures following tissue damage or breakdown. The original site lists synovitis, capsulitis, discitis and inflammatory or rheumatoid arthritis. These disorders are described as often causing a persistent dull ache that can worsen with mouth movement.