NORMAL JAW JOINT
When the lower jaw opens and closes, the disc stays
between the condyle and the glenoid fossa of the
temporal bone at all times. When this happens, this
is a normal healthy TMJ and the patient can open
wide without any discomfort and without any noise.
With a normal opening, the patient should be able to
get three fingers between the upper and lower front
teeth when the mouth is open as wide as possible. In
cases where the TM joint is functioning normally
with the disc in the proper position, the muscles of
the head, neck and shoulders function relatively
pain-free.
What is TMD?
Temporomandibular disorder (TMD)
is the condition referring to a joint that is not
normal.
The position of your teeth can
affect the position of your jaw joints. Each jaw
joint is a ball and socket joint. When functioning
properly, the ball and socket do not actually touch
because a thin disc of cartilage rides between them.
The disc acts as a cushion and allows the joint to
move smoothly. Each disc is held in place and guided
by muscles and ligaments. If your bite is not right,
as in cases where the following may occur: deep
overbite, lower jaw too far back, narrow upper jaw
or upper front teeth crooked and tipped backwards,
this can cause the jaw to become dislocated.
Typically the disc is pulled forward. The lower jaw
then has a tendency to go back too far and the top
of the lower jaw, which resembles a ball (condyle),
presses on the nerves and blood vessels at the back
of the socket and causes pain.
Usually, the protective disc
(cartilage) is displaced forward and no longer
serves as a cushion between the condyle (lower jaw)
and the bony socket (skull) and eventually this can
lead to the condyle rubbing against the bony socket.
This can cause a problem called osteoarthritis.
Mild displacements cause a
clicking or popping sounds in the jaw joint.
