Mysteries of TMD
Many causes, many symptoms
The most common symptom of TMD is pain in the jaw joint or the muscles when chewing, according to the NIH's National Institute of Dental Research. Other symptoms include clicking, popping, or grating sounds in the jaw when opening or closing the mouth, or a change in the way the upper and lower teeth fit together. TMD patients also may suffer limited movement or locking of the jaw, headaches, earaches, dizziness, or ringing in the ears.
But because TMD includes so many different conditions, its causes vary widely and in most cases are simply unknown. "TMD is really a garbage term," says David Cottrell, MD, associate professor and director of the Oral Maxofacial Residency Program at Boston University Medical School. "It could be one of 15 different things. In most cases, we don't know the exact cause." Nor do researchers know why the disorder strikes women far more frequently than men. Hormones may play a role because patients often report improvement during pregnancy, explains Cottrell.
Rheumatoid arthritis and Lyme disease also can cause TMD because these diseases affect joints. So can psoriasis, a chronic skin disorder that can have several components, such as scaly patches, but also may cause arthritis. Trauma, such as the car accident that injured Zee, is another culprit, although Zee says she believes undiagnosed arthritis already had weakened her jaw and the blow she received "finished off" the disc.
Oftentimes, stress is to blame, as along with stress come such habits as teeth grinding and jaw clenching. And in a recent study, poor posture seemed to be at the root of the problem. An Air Force study published in the February 2000 issue of the Journal of the American Dental Association showed that posture training reduced symptoms by 42% in a group of patients who had suffered for at least six months from TMD.
Treat with caution
While causes of TMD remain elusive, most TMD sufferers can find some relief in any number of treatments. Cottrell estimates that more than 80% of his patients recover on their own once they understand the problem and are careful about what they eat and how they open their mouths. Ten percent find relief by wearing a plastic mouth guard during the night that prevents jaw clenching or teeth grinding during sleep.