Because healthy, injury-free temporomandibular joints allow your jaw to move smoothly and without pain, most people don’t notice them until they don't work as they should. The exact cause of a person's TMJ disorder is often difficult to determine. Your pain may be due to a combination of factors, such as genetics, arthritis or jaw injury. In general, TMJ disorders are more commonly caused by muscle problems but they can also be caused by either damage to the cartilage that cushions the joint from the jawbone, or by damage to the small, shock-absorbing disc that sits between the joint and the bone that helps keep joint movement fluid.
Disorders of the jaw joint and chewing muscles—and how people respond to them—vary widely. Also, how jaw joint and muscle disorders progress is not clear. The three main categories of TMJ disorders are:
- Myofascial pain involves discomfort or pain in the muscles that control jaw function.
- Internal derangement of the joint involves a displaced disc, dislocated jaw, or injury to the condyle.
- Arthritis refers to a group of degenerative/inflammatory joint disorders that can affect the temporomandibular joint.
Although it’s not always possible to diagnose the exact cause of TMJ pain, there are specific factors that can increase your risk of developing the problem. Women are more likely to develop a TMJ problem, as are people who have had a past jaw injury. Having any type of arthritis, including rheumatoid arthritis, osteoarthritis, or fibromyalgia, can also increase your risk.