TMJ & Sleep Therapy Office of London, Ontario with Dr. David Rawson
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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

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 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 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 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:

  1. 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.

  2. 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).

  3. 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.

  4. Neurologic examination to test for nerve or brain damage that may cause TMJ symptoms.

  5. 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.

  6. 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.

Normal Joint

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

Learn about the Causes

Learn about Diagnosis and Treatment of TMD