The set of TMJ disorders are complex and have a variety of underlying causes, not all of which are fully known. It is widely accepted among dental professionals that TMJ disorders can usually be traced back to problems with the joint and the muscles involved in opening and closing of the jaw. However, while injury to the jaw area is often seen among TMJD cases, many times symptoms may be present without obvious cause.
According to the Academy of Orofacial Pain, the causes of TMJD are unclear in large part due to the current theory that the condition is actually the result of several factors working together. Possible contributing factors to inflammation of the temporomandibular joint include:
- Injury to the jaw, including whiplash or stretching due to insertion of a breathing tube.
- Teeth clenching and grinding
- Dental procedures
- Auto-immune diseases
The role of teeth grinding due to stress is also complicated by scientific research that shows many habitual tooth grinders never show symptoms of pain or discomfort of the jaw, while an individual with soreness in the jaw is less likely to grind his or her teeth due to the pain, and that any reported stress can be a result of the painful condition.
One early theory about a possible cause for TMJD was orthodontics, however that belief has been dismissed with scientific evidence. There is current research underway into a possible link between TMJD and hormones because women are more likely than men to experience TMJ pain and soreness.
Disorders of the temporomandibular joint can be categorized in two main groups: myogenous TMJD and arthrogenous TMJD. Myogenous refers to a condition affecting the muscles, usually brought on by overwork or tension in the jaw and supporting muscles. Arthrogenous refers to a joint related condition in either the hard or soft tissues or both, including disc dislocation and arthritis degeneration.
Part of the reason that there is still no agreement among healthcare professionals about the exact causes of TMJD is that TMJ disorders are complex and are likely the result of several circumstances and conditions. Typically a patient will report multiple symptoms as part of the condition and may have experienced more than one of the above listed co-factors.