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.