Temporomandibular Jaw Disorders
(TMD, TMJ Syndrome)

Temporomandibular joint disorder, commonly known as TMJ or TMD, is a term used to describe symptoms affecting the temporomandibular joint; the joint that attaches the lower jaw to the side of the head. You can feel it if you situate your fingers on the side of the face underneath the ears.

TMJ disorder is relatively common but it is not fully understood by many people. A lot of patients will have been diagnosed with TMJ disorder without really knowing what it is, and research into symptoms and signs of TMJ disorder are ongoing. TMJ disorder is not a single condition but a range of conditions and symptoms, which have an effect on the jaw joint and the actions of chewing, yawning and biting down on objects.

It is not known exactly how many people suffer from TMJ disorder, but the condition is twice as common in women as men. In most cases, the symptoms are mild and short-term and tend to subside without any need for treatment. More severe cases which cause noticeable or persistent symptoms may require treatment. It is uncommon for people with TMJ disorder to develop symptoms that are long-lasting.

What is the temporomandibular joint?

The temporomandibular joint is that which attaches the mandible (lower jaw) to the temporal bone in the side of the face. The joint is designed to glide smoothly, enabling the mouth to open and bringing about actions such as biting, chewing and yawning. The movement of the jaw joint is controlled by the facial muscles surrounding the joint.

When you open your mouth the condyles (rounded ends of the lower jaw) slide along the socket to the temporal bone. They then slide back when the mouth is closed. The action is smooth thanks to a small disc located between the temporal bone and the condyle. The disc acts as a shock absorber during jaw movement.

What are temporomandibular joint disorders?

Most experts agree that temporomandibular disorders can be classified into three categories, including:

• Myofascial pain: this is the main form of TMJ disorder and causes pain in the muscles around the jaw joint.
• Internal derangement of the joint: this form of TMD is associated with dislocation of the joint or displacement of the disc positioned between the temporal bone and the condyle, which can be caused by damage to the condyle.
• Degenerative joint disease: this relates to conditions such as rheumatoid arthritis or osteoarthritis which cause gradual degeneration of the joints.

In some cases, people have symptoms of more than one form of TMD.

What causes TMJ disorder?

Injury or trauma can cause TMJ disorder; this could involve a direct blow to the face, causing injury to the joint or the protective disc. If the disc is injured or damaged the jaw joint may be unable to move smoothly, resulting in pain and the possibility of the jaw locking. Injuries to the jaw joint also have the potential to cause arthritis contributing to stiffness in the joint.

Other causes of TMJ disorder are less well-documented. Some experts propose that malocclusion (a bad bite) can cause TMJ disorder, but there is evidence to dispute this claim. It has also been suggested that orthodontic treatment used to correct the bite and align teeth can actually cause symptoms associated with TMD.

There is no evidence to suggest that chewing gum on a regular basis causes TMJ disorder, even when the jaw starts clicking. Jaw clicking is moderately common and there is usually no need for treatment unless an individual has additional symptoms.

Researchers believe that most people who experience jaw popping or clicking have a displaced disc. This prevents the jaw joint from moving smoothly, but if there is no pain then no treatment is usually required.

Some experts have proposed the notion that stress and anxiety are connected to TMJ disorder. Often, people with TMJ disorder grind or clench their teeth during night and this may be made worse by stress. Researchers are currently investigating the relationship between psychological and physiological factors associated with TMJ disorder.

TMJ disorder signs and symptoms

There are many symptoms associated with TMJ disorder. The most common is pain which tends to be experienced around the jaw joint. Other symptoms include:

• Restricted jaw movement.
• Jaw clenching and clicking.
• Pain in the face that may radiate to other parts of the body, including the neck and shoulders.
• Popping and grating sounds occurring when you move the jaw joint.
• A sudden change in the alignment of the lower and upper sets of teeth.

Other signs such as headaches, dizziness, hearing problems and feeling dizzy may also be associated with TMJ disorder. In most cases, symptoms wear off quickly and no treatment is required.

How is TMJ disorder diagnosed?

Diagnosing TMJ disorder can be difficult because the symptoms and causes of the disorder are unclear. At the moment there are no set criteria for diagnosing TMJ disorder. In 90 percent of cases symptoms and physical examination are sufficient for doctors or dentists to reach a diagnosis.

During the examination the doctor will feel the jaw joint and check for signs such as popping, restricted movement and muscular pain when the jaw opens and closes. It is important for doctors to check the patient's medical and dental history. Checking the patient's history, physical examination and relevant symptoms enable doctors to establish a diagnosis and start the treatment process, if required.

In some cases, diagnostic tests such as X-rays and MRI (magnetic resonance imaging) scans are required. MRI and tomography scans are generally required when a doctor suspects underlying health problems, such as arthritis, or if pain is persistent or getting worse.

Treating TMJ disorder

Treatment for TMJ disorder is usually associated with the words 'conservative' and 'reversible'. Conservative treatments are the most simple and do not involve any invasive techniques. They are normally used because most people only have mild, short-term symptoms. Conservative procedures do not interfere with the facial tissues and reversible procedures do not cause any permanent or irreversible effects.

Simple treatments are usually recommended for TMJ disorder as most people do not have long-term or severe symptoms. Self-help techniques can be effective in easing symptoms and include:

• Sticking to a soft food diet.
• Applying ice to the jaw joint to reduce pain and swelling (always ensure the ice pack is covered with a towel to prevent damage to the skin).
• Avoid large jaw movements.
• Managing stress (this may include taking time to relax, exercising or massage therapy, for example).

Other conservative treatments include physiotherapy and exercises you can perform at home and taking anti-inflammatory medication. The exercises should improve movement in the jaw joint.

In some cases, a bite plate or splint may be required to reduce tension and prevent teeth grinding and clenching. These can otherwise contribute to symptoms of TMJ disorder. Oral splints should not be worn for a long period of time, so if the splint causes pain it should be removed.

Conservative and reversible treatments are designed to ease symptoms but they will not cure TMJ disorder.

If symptoms are severe or persistent more intensive treatment may be required such as injections and surgery. Pain relief medication can be injected into specific trigger points around the joint, but research into their effectiveness is ongoing.

Surgery is usually considered a last resort and is rarely used for TMJ disorder. Surgery is irreversible and there is concern that surgical procedures, including artificial implant placement, can cause jaw pain and long-lasting damage to the jaw. If a surgeon recommends surgery they will outline the risks associated with the procedure and weigh these against the benefits.

Other irreversible procedures such as orthodontic treatment to improve bite and restorative treatment have been described by researchers as ineffective.

Most experts agree that TMJ disorder treatment should involve conservative methods, although research in this area is ongoing.

If you suspect you have TMJ disorder

If you experience symptoms of TMJ disorder, such as pain in and around the joint, clenching and clicking noises and a limited range of movement in the jaw, you should see your doctor or dentist. It is rare for patients to need invasive treatment and many find that their symptoms ease without any need for treatment. If symptoms persist or become more severe, you should see your doctor as soon as possible.