What causes TMD?

How jaw joint and muscle disorders progress is not clear. Symptoms worsen and ease over time, but what causes these changes is not known. Many people have relatively mild forms of the disorder. Their symptoms improve significantly, or disappear spontaneously, within weeks or months. For others, the condition causes long-term, persistent and debilitating pain.

Trauma to the jaw or temporo-mandibular joint plays a role in some TMJ disorders. But for most jaw joint and muscle problems, clinicians don’t know the causes. For many people, symptoms seem to start without obvious reason. There is no conclusive evidence that a bad bite or orthodontic changes can trigger TMJ disorders. However there is anecdotal evidence and many dentists believe there is a relationship in some people. The condition is more common in women than men and there may be a hormonal link.

The roles of stress and tooth grinding as major causes of TMJ disorders are also unclear. Many people with these disorders do not grind their teeth, and many long-time tooth grinders do not have painful joint symptoms. Scientists note that people with sore, tender chewing muscles are less likely than others to grind their teeth because it causes pain.

Researchers also found that stress seen in many persons with jaw joint and muscle disorders is more likely the result of dealing with chronic jaw pain or dysfunction than the cause of the condition.

What are the signs and symptoms?

A variety of symptoms may be linked to TMJ disorders. Pain, particularly in the chewing muscles and/or jaw joint, is the most common symptom. Other likely symptoms include:

  • radiating pain in the face, ear, jaw, or neck,
  • jaw muscle stiffness,
  • limited movement or locking of the jaw,
  • painful clicking, popping or grating in the jaw joint when opening or closing the mouth,
  • a change in the way the upper and lower teeth fit together.