TMJ syndrome

What Is the Temporomandibular Joint?

The temporomandibular joint connects the lower jaw, called the mandible, to the temporal bone at the side of the head. If you place your fingers just in front of your ears and open your mouth, you can feel the joint on each side of your head. Because these joints are flexible, the jaw can move smoothly up and down and side to side, enabling us to talk, chew and yawn. Muscles attached to and surrounding the jaw joint control its position and movement.

When we open our mouths, the rounded ends of the lower jaw, called condyles, glide along the joint socket of the temporal bone. The condyles slide back to their original position when we close our mouths. To keep this motion smooth, a soft disc lies between the condyle and the temporal bone. This disc absorbs shocks to the TMJ from chewing and other movements.

Temporomandibular Disorders Types

Most researchers believe there to be three types of disorders:

• myofascial pain, the most common form of TMD, which is discomfort or pain in the muscles that control jaw function and the neck and shoulder muscles;
• internal derangement of the joint, meaning a dislocated jaw or displaced disc, or injury to the condyle;
• degenerative joint disease, such as osteoarthritis or rheumatoid arthritis in the jaw joint.

A person may have one or more of these conditions at the same time.

Causes of TMD

The cause of TMJ is still not fully understood; although researchers believe there could be a number of factors or combination of factors that may contribute.

Injury
We know that severe injury to the jaw or temporomandibular joint can cause TMD. A heavy blow, for example, can fracture the bones of the joint or damage the disc, disrupting the smooth motion of the jaw and causing pain or locking.

Arthritis
Arthritis in the jaw joint may also result from injury. Other causes of TMD are less clear. Some suggest, for example, that a

Bad Bite
Some research suggests that a bad bite (malocclusion) can trigger TMD. Orthodontic treatment, such as braces and the use of headgear, has also been blamed for some forms of TMD, but studies now show that this is unlikely. There is also thoughts that improperly fitted mouthguards can cause TMJ or TMD.

Stress
Some specialists believe that mental or physical stress may cause or aggravate TMD. People with TMD often clench or grind their teeth at night, which can tire the jaw muscles and lead to pain. It is not clear, however, whether stress is the cause of the clenching/grinding and subsequent jaw pain, or the result of dealing with chronic jaw pain or dysfunction. Scientists are exploring how behavioral, psychological and physical factors may combine to cause TMD.

Signs and Symptoms

A variety of symptoms may be linked to TMD. Pain, particularly in the chewing muscles and/or jaw joint, is the most common symptom. Other likely symptoms include:

• limited movement or locking of the jaw,
• radiating pain in the face, neck or shoulders,
• painful clicking, popping or grating sounds in the jaw joint when opening or closing the mouth. Note though that there is some evidence that jaw clicking leads to serious TMJ problems. In fact, jaw clicking is fairly common in the general population and may be attributed to a displaced disc- often a harmless condition that does not need treatment. If there are no other symptoms, such as pain or locking, jaw clicking usually does not need treatment.
• a sudden, major change in the way the upper and lower teeth fit together.
• Symptoms such as headaches, earaches, dizziness and hearing problems may sometimes be related to TMD.

Note that it is also common to experience jaw joint or pain when chewing, etc. and is often not a cause for concern.

Diagnosis

Diagnosing this TMD can be difficult as the exact cause and symptoms are not clear. Medical professionals usually rely on a basic exam of the face and jaw as well as on the patient's description of symptoms.

The examination includes feeling the jaw joints and chewing muscles for pain or tenderness; listening for clicking, popping or grating sounds during jaw movement; and examining for limited motion or locking of the jaw while opening or closing the mouth. Checking the patient's dental and medical history is very important. In most cases, this evaluation provides enough information to locate the pain or jaw problem, to make a diagnosis, and to start treatment to relieve pain or jaw locking.

Regular dental X-rays and TMJ x-rays (transcranial radiographs) are not generally useful in diagnosing TMD. Other x-ray techniques, such as arthrography (joint x-rays using dye); magnetic resonance imaging (MRI), which pictures the soft tissues; and tomography (a special type of x-ray), are usually needed only when the practitioner strongly suspects a condition such as arthritis or when significant pain persists over time and symptoms do not improve with treatment. Before undergoing any expensive diagnostic test, it is always wise to get a second medical opinion.

Treatment

Conservative and totally reversible treatments

It is recommended to attempt these more conservative treatments first:

Because most TMD problems are temporary and do not get worse, simple treatment is all that is usually needed to relieve discomfort. Some find the following treatments to be helpful:

• Eat soft foods
• Apply heat or ice packs
• Avoid extreme jaw movements (such as wide yawning, gum chewing, etc.) *Practice special techniques for relaxing and reducing stress.
• If you grind or clench your teeth at night, attempt biofeedback or guided meditation/hypnosis before falling asleep.
• Make sure that you have a proper ergonomic set up if you work at a computer. you do not want your head to be jutting forward, or downward too much - you want your head to be in line with your neck so that the jaw is in the most relaxed position.

Slightly more aggressive conservative treatments

• physical therapy excercises you can get from a specialist and practice at home; this would include gentle muscle stretching and relaxing exercises, and short-term use of muscle-relaxing and anti-inflammatory drugs.

• oral appliance known as mouth splint, bite plate or mouth guard, which is a plastic guard that fits over the upper or lower teeth. The splint can help reduce clenching or grinding, which eases muscle tension. An oral splint should be used only for a short time and should not cause permanent changes in the bite. If a splint causes or increases pain, stop using it and see your practitioner.

These conservative, reversible treatments described are useful for temporary relief of pain and muscle spasm -- they are not "cures" for TMD. If symptoms continue over time or come back often, check with your doctor.

Surgery and Injections as treatment

• Doctors can inject pain relieving medications into painful muscle sites, often called "trigger points." Researchers are studying this type of treatment to see if these injections are helpful over time.
• Surgical treatments are often irreversible and should be avoided where possible. When such treatment is necessary, be sure to have the doctor explain to you, in words you can understand, the reason for the treatment, the risks involved, and other types of treatment that may be available. Scientists have learned that certain irreversible treatments, such as surgical replacement of jaw joints with artificial implants, may cause severe pain and permanent jaw damage.

• Other irreversible treatments that are of little value -- and may make the problem worse -- include orthodontics to change the bite; restorative dentistry, which uses crown and bridge work to balance the bite; and occlusal adjustment, grinding down teeth to bring the bite into balance.

They key is start with the most reversible and least invasive treatments first.

If You Think You Have TMD...

Keep in mind that for most people, discomfort from TMD will eventually go away whether treated or not. Simple self-care practices are often effective in easing TMD symptoms. If more treatment is needed, it should be conservative and reversible. Avoid, if at all possible, treatments that cause permanent changes in the bite or jaw. If irreversible treatments are recommended, be sure to get a reliable second opinion.

Many practitioners, especially dentists, are familiar with the conservative treatment of TMD. Because TMD is usually painful, pain clinics in hospitals and universities are also a good source of advice and second opinions for these disorders. Specially trained facial pain experts can often be helpful in diagnosing and treating TMD.

References

• National Institute of Dental and Craniofacial Research,

National Institutes of Health; phone: 301/496-4261 web: www.nidcr.nih.gov