We
know that severe injury to the jaw or temporomandibular
joint can cause TMD. A heavy blow, for example, can
fracture the bones of the joint or damage the disc,
disrupting the smooth motion of the jaw and causing
pain or locking. Arthritis in the jaw joint may also
result from injury. Other causes of TMD are less clear.
Some suggest, for example, that a bad bite (malocclusion)
can trigger TMD, but recent research disputes that
view. Orthodontic treatment, such as braces and the
use of headgear, has also been blamed for some forms
of TMD, but studies now show that this is unlikely.
And
there is no scientific proof that gum chewing causes
clicking sounds in the jaw joint, or that jaw clicking
leads to serious TMJ problems. In fact, jaw clicking
is fairly common in the general population. If there
are no other symptoms, such as pain or locking, jaw
clicking usually does not need treatment.
Researchers
believe that most people with clicking or popping
in the jaw joint likely have a displaced disc -- the
soft, shock-absorbing disc is not in a normal position.
As long as the displaced disc causes no pain or problems
with jaw movement, no treatment is needed.
Some
experts suggest that stress, either mental or physical,
may cause or aggravate TMD. People with TMD often
clench or grind their teeth at night, which can tire
the jaw muscles and lead to pain. It is not clear,
however, whether stress is the cause of the clenching/grinding
and subsequent jaw pain, or the result of dealing
with chronic jaw pain or dysfunction. Scientists are
exploring how behavioral, psychological and physical
factors may combine to cause TMD.
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