What Is TMJ?
 “TMJ”
stands for temporomandibular joint, or the jaw
joint. In fact, there are really two TMJs, one
in front of each ear. The TMJ is the joint formed
by the temporal bone of the skull (temporo) with
the lower jaw or mandible (mandibular). These
joints move each time we chew, talk or swallow.
Unlike the shoulder or knee, which are ball-and-socket
joints, the TMJ is a sliding joint. The sliding
allows for pressure placed on the joint to be
distributed throughout the joint and not just
in one area. Adding to the joint’s complexity
is that between the two bones that make up the
TMJ (the temporo and mandibular) is a disc, just
like those between the bones on your back. Made
primarily of cartilage, in the TMJ the disc acts
like a third bone. Because it is attached to a
muscle, the disc actually moves with certain movements
of the TMJ.
One of the difficulties with diagnosing a TMJ
disorder is identifying the exact source of the
problem. For example, the nerve to the TMJ is
a branch of the trigeminal nerve. An injury to
this nerve in the TMJ may be confused with neuralgia
because the symptoms appear to be the same. The
two bones of the TMJ are held together by a series
of ligaments, any of which can be damaged. A damaged
TMJ ligament usually results in a dislocation
of the disc, the lower jaw, or both. Another possible
problem may be from muscles that are connected
to the bone. A muscle injury may produce pain
in the TMJ or abnormal movement of the lower jaw.
Careful diagnostic study and testing is needed
to determine the precise source of any TMJ problem.
A TMJ disorder is simply a disruption in the
action of the jaw, usually accompanied by pain.
There are a number of conditions affecting the
function of the jaw that can cause one of these
disorders. Fortunately, because the jaw is made
up of bone and other living tissue, it is alive,
making it capable of repair and healing.
Any malfunction prevents the complex system of
muscles, bones and joints working together in
harmony. The result is a TMJ disorder – also
known as TMD or CMD (cranio-mandibular dysfunction).
Generally, a malfunction of one or both of these
jaw joints is caused by trauma, whiplash, bad
bite (malocclusion), poor posture, teeth grinding
or skeletal malformation. It is estimated that
one in every four people suffer from TMJ symptoms.
Symptoms
People with TMJ problems generally experience
one or more of the following symptoms:
- Chronic recurring headaches
- Clicking, popping or grating sound in the
jaw joints
- Earaches, congestion or ringing ears
- Limited jaw opening or locking
- Dizziness
- Pain when chewing
- Neck and/or throat pain
- Difficulty in closing the teeth together
- Tired, tight jaws
- Pain behind the eyes
- Scalp tenderness
- Swallowing difficulty
- Pain in the tongue, gums or cheek muscles
- Teeth grinding or clenching
How Is TMJ Diagnosed?
Depending on the nature and severity of the problem,
the evaluation of hard tissues my be accomplished
using x-rays and CT scans. Soft tissue is evaluated
using MRIs, Joint Vibration Analysis (JVA) and
electromyography (EMG). Jaw movements are documented
using the Jaw Tracker (JT). Occlusion is evaluated
using the T-Scan. More information about these
diagnostic technologies appears on the Treatments
page.
The evaluation process will include:
Detailed Medical and Dental History.
A complete medical history must be documented,
including all past medical and/or dental problems
and treatments, any history of trauma (especially
to the head and neck region), specific questions
about your symptoms, and the nature and duration
of any pain and jaw problems.
Physical Examination.
A complete physical examination for a TMJ problem
will likely include:
- Postural exam to discover any musculoskeletal
problems that either contribute to or are
the result of TMJ problems. This includes
scoliosis, lower back pain and short leg syndrome,
among others.
- A cranial examination to evaluate the planes
of the skull, including the alignment of the
jaw joints and mouth to the rest of the body
(dental plane of occlusion).
- Dental examination to evaluate the shape
of the dental arches, swallowing patterns,
tooth wear or fractures, missing teeth, existing
dental restorations or other clues. The dentist
will usually make models of the mouth so that
the teeth and dental arches can be more closely
examined.
- Neurologic examination to test for nerve
or brain damage that may cause TMJ symptoms.
- TMJ examination to look at the ranges of
motion, gait, speed and smoothness of jaw
movement. Additionally, the TM joints will
be checked for internal joint inflammation,
pain and the presence of joint sounds.
- Joint Vibrational Analysis, a non-invasive
technology that records the vibrations made
by joint tissues during movement. The patterns
and electronic signature of the patient’s
joints are compared with known standards for
healthy joints, providing objective proof
of a TMD.
Learn about the Causes
of TMD
Learn about Diagnosis and
Treatment of TMD
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