Posted By: Jenny Lee, D.D.S. | Thursday, October 18, 2012

What is TMJ?

TMJ is an abbreviation for temperomandibular joint. The jaw joint is right in front of the ear. You can feel it with your fingers when you open or close your mouth. When you have pain, clicking or inability to move your jaw, you have temperomandibular joint dysfunction, or TMD. It is estimated that between 10% and 20% of the population suffer from TMD, at some time in their lives. If you think you might have TMD, this quick Risk Assessment Test will help you decide if you need to read further.

How does the temperomandibular joint work?

The following video demonstrates how the jaw joint or temperomandibular joint works. (link to video). The jaw joint is a perhaps the most complicated joint in the body. Most joints, like your knee joint, are ball and socket joints. They can rotate, as your knee does when you bend it. The temperomandibular joint can also rotate, which it does when you open and close. But it is very special. It can also translate when you move your jaw forward to touch your front teeth together. Look at the diagram below. In order to be able to do this, it has a cartilage disc between the ball and socket of the joint. In this diagram, the disc is shaded purple. The disc is like a donut that moves with the joint when it translates forward. It is attached to the back wall of the jaw by an elastic tether. The TMJ is an elegant and sophisticated part of our anatomy, but like all complicated equipment, it is prone to breaking down.

Muscle Induced TMD

Most TMD is muscle pain. You can feel achy, stiff or sore in the muscles of your jaw, neck or temples. It can be the result of stress-related squeezing your teeth during the day or night. The muscles go into spasm, producing a cycle of spasm-pain-more clenching-more spasm-and more pain . . . Most muscle related episodes of TMD seem to be related to temporary periods of stress, and resolve on their own within a week or two.

When related TMD becomes chronic, there is an underlying cause that must be resolved. Common causes:

  • Tooth bruxism or clenching while sleeping.
  • Habitual tooth clenching during the day.
  • Uneven bite.
  • Clenching induced by medications.
  • Clenching induced by certain diseases.
  • Damage to the joint by trauma to the face.

When should I seek professional help?

When jaw pain lasts longer than two weeks, when you are unable to open or close your mouth, or when the pain is severe, you should seek medical treatment. A dentist or physician trained in TMD treatment can help you manage the acute symptoms and limit permanent damage.

Disc Displacement With Reduction

When the pain is chronic or the trauma is severe, the joint can be damaged. The disc, which cradles the ball and socket of the joint, can become damaged by severe acute trauma, such as in a car accident, or by repeated stress, for example from clenching.

In these cases, the temperomandibular joint becomes permanently damaged. The mildest form is a slight click that occurs when the disc slips partially out or into place. Each click further flattens the disc and makes the next click more likely. Patients often feel no pain during this phase.

When the disc slips completely out of the joint, the patient:

  • May feel severe pain. The muscles are often in spasm, and the jaw joint may be pressing on very sensitive tissues.
  • May have limitation of opening or closing of her jaw. The disc may be in the way.
  • May be able to massage or wiggle the disc back into place. If the disc slips out completely, the elastic tether is stretched. The cycle of disc injury and TMD events accelerate, as the shape of the disc and elastic tether become further damaged.

Disc Displacement without Reduction

When the disc permanently slips out of position, the patient initially experiences:

  • Pain. The muscles are often in spasm, and the jaw joint may be pressing on very sensitive tissues.
  • Limitation of opening or closing the jaw. The disc may be in the way.
  • She cannot wiggle or massage the disc back into place.
  • No clicking at all. The disc no longer clicks back into place.
  • The bite will be uneven, due to the change in shape of the TMJ
  • A grating sound. This is the noise of the bone from the ball and socket grating on each other.

The joint with disc displacement without reduction will change shape over time. The patient will continue feel painful episodes when stressed by chewing or talking, but there will be a reduction in pain as the joint adapts. There will be a gradual increase in jaw mobility as the unused disc gets worn away. The damage to the joint will be limited by an even bite, which will have to be regularly adjusted due to the continual wear of the joint.

How can you prevent Advanced TMD?

  • Be aware of clenching habits during the day.
  • Wear a nightguard if you clench at night. Link to Treatments: Nightguards
  • If your bite feels uneven, consult your dentist to resolve the problem.
  • During periods of mild temporary stress:
    • massage your jaw muscles.
    • eat a soft or liquid diet.
    • Use Advil as directed.
    • Use moist heat on the joint.

If you have an acute episode of TMD, consult a dentist or physician who is competent in the treatment of TMD. When TMD is chronic, the patient may need ongoing management of the disease. The following treatments may be recommended:

  • Pain relievers.
  • Restrictive diets.
  • Muscle relaxants.
  • Nightguards Link to Treatments: Nightguards
  • Physical therapy and massage therapy.
  • Heat treatment.
  • Tens Treatment.
If you have chronic TMD your dentist or physician:
  • May recommend injections of steroids, Botox or pain relievers.
  • May recommend surgery.
  • May create a new balanced bite. Link to Treatments: Bite Balancing