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 joints 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
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.
People with TMJ problems generally experience
one or more of the following symptoms:
Chronic recurring headaches
Clicking, popping or grating sound in the
Earaches, congestion or ringing ears
Limited jaw opening or locking
Pain when chewing
Neck and/or throat pain
Difficulty in closing the teeth together
Tired, tight jaws
Pain behind the eyes
Pain in the tongue, gums or cheek muscles
Teeth grinding or clenching
How The Diagnosis Of TMJ Helps Treat Sleep Apnea
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
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.
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,
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
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 patients
joints are compared with known standards for
healthy joints, providing objective proof
of a TMD.
As in all joints in the body, the bones should never rub together but be separated by dense fibrous tissue called disks. In the jaw (TMJ) it is more complicated than a knee or hip as we have both left AND right joints attached to the same bone. As well, as many as 32 teeth must interact with the 2 double jointed ends of the mandible. This makes Temporomandibular Joint (TMJ) function very complicated and difficult to treat. TM joints actually move right out of the bony socket in normal function which is impossible in other parts of the body. Notice how the disk slides along with the mandible and provides a separation between the skull and the joint at all times. A healthy jaw will move smoothly and quietly without any restriction or pain. We very rarely see these healthy joints in our TMJ practice!
Dental Normal Joint
Anterior Dislocation upon Movement of the Jaw
Here you will notice how the disc slips forward and backwards off the head of the jaw joint (condyle) as the jaw joint actually moves in and out of the socket. This slippage is often called a "click" or "pop" by the patient as the TMJ is very close to the ear. This is the most common finding in early cases of TMJ and can be easily treated non-surgically and without drugs.
Anterior Disk Displacement with Reduction
Medial Dislocation of the Disc
In this case the disc is not as obvious as in video # 2 ( anterior dislocation) because it is actually being pulled towards the centre of the body and so is less invisible in this view. These are later stage dislocations, often quieter , can be more serious and have been found to be contributors to migraines and chronic daily headaches. We can still treat these non-surgically if caught in time.
Medial Disk with Reduction
Advanced Degenerative Joint Disease with Disc Perforation
This is the end stage of TMJ disease where the disc has been pounded flat after many years of traumatic use (clenching and bruxing) and may even have with holes (perforations) worn through. Here the bones are actually rubbing together and patients report a hard, grating sound called crepitis. This would be comparable to knees and hips where the disks wear out and patients are unable to walk or stand without physical assistance. Luckily Mother Nature has provided us with more durable jaw joint disks and even these cases can be regularly treated non-surgically with long-lasting results of a pain free life.
Degenerative Joint with Disease with Large Perforation