Temporomandibular Joint Disorders

What are temporomandibular joint disorders?

Temporomandibular joint disorders are problems which affect the jaw joint. This joint is located just in front of the ear canal, and it joins the jaw bone (mandible) to the skull near to the temple. There are various names for this condition. The jaw joint is also called the temporomandibular joint or 'TMJ'. Problems affecting this joint can be called TMJ disorders, TMJ dysfunction or TMJ pain.

Understanding the jaw joint

A joint is where two bones meet. Joints allow movement and flexibility of various parts of the body. The movement of the bones is cased by muscles which pull on tendons that are attached to bone. Cartilage covers the end of bones. In the jaw joint, there is also a cartilage disc within the joint. Inside the joint there is a small amount of thick fluid called synovial fluid. This fluid lubricates the joint which allows smooth movement between the bones.

What are the symptoms of TMJ disorders?

• Pain in the joint area or nearby. You may feel the pain just in front of the ear, and it may spread to the cheek, the ear itself, and to the temple.
• Jaw movements may be reduced. This may be a general tight feeling or a sensation of the jaw getting stuck. Very rarely, the jaw may get ‘locked’, causing difficulty in opening or closing the mouth.
• Because the ear is very close to the jaw joint, some people get ear symptoms such as noise in the ear, sensitivity to sound or dizziness (vertigo).
• Clicks or noises can sometimes be heard coming from the jaw joint when you chew or move your mouth. These noises can be quite normal, so they are only relevant if you have other symptoms in the joint such as pain or reduced movement.

How common are TMJ disorders?

They are fairly common. About 1 in 10 people have symptoms in the jaw joint at some time in their lives. Of these people, only about 1 in 20 consult a doctor for this problem.

What causes TMJ disorders?

Problems in this area are of two types: problems related to the muscles working the joint, and problems in the joint itself. As a general rule, muscle problems are the most common cause, especially in younger people. Problems in the joint itself are less common and usually affect older people.

Problems with the muscles may be due to:

• Overactivity of the jaw muscles. This can occur if you clench your jaw a lot during sleep, which is quite common. Rarely, other conditions make the jaw muscles overactive. For example, there are some rare kinds of movement disorders called ‘orofacial dystonias’ which cause excessive jaw clenching.
• Another cause of muscle-type problems is when the muscles around the jaw joint become more sensitive to pain. We don’t know why this happens, but it may be linked to stress, or to some other process which affects pain sensitivity. Some doctors call this type of problem a ‘pain syndrome’ because the exact cause of the pain is not known.

Problems in the joint itself can be caused by:

• Wear and tear of the joint, or of the cartilage disc inside the joint. This tends to affect older rather than younger people.
• Arthritis. Arthritis is a general name which means inflammation in a joint. There are different kinds of arthritis, which can affect various joints in the body. For example, rheumatoid arthritis and gout are both types of arthritis which can sometimes affect the jaw joint.
• Rarely, the jaw joint can dislocate (meaning the bone slips out of its normal place in the joint).

How are TMJ disorders diagnosed?

Often, no tests are necessary if you are healthy and have symptoms that are typical of a TMJ disorder.

If the cause is uncertain, blood tests may be helpful to look for signs of inflammation, or to test for for particular problems such as cranial arteritis (see below).

An MRI scan is sometimes used to get a picture of what is happening in the joint itself. X-rays are another option, but are used less often now that MRI scans are available.

What else could it be?

Other causes of pain in this area are:

• Cranial arteritis (also known as 'temporal arteritis'). This only affects people over age 50, and usually causes headaches, muscle pains around the shoulders, tiredness or fevers, pain on chewing, and possibly reduced vision. It needs urgent treatment, so if you have this combination of symptoms, and especially with reduced vision, see a doctor immediately.
• Migraines and a condition called 'trigeminal neuralgia' can also cause pain on one side of the face.
• Problems in the ear or behind the jaw sometimes cause pain in the jaw joint area.

What is the treatment for TMJ disorders?

Most problems in the jaw joint can be helped with simple treatments such as painkillers and advice on how to rest the joint. There are various treatments which are often used in combination:

Resting the jaw joint

You can rest the joint by eating soft food and not using chewing gum. Also, avoid opening the mouth very wide - so don’t do too much singing, and try not to yawn too widely. Massaging the muscles and applying warmth can help. Other treatments are relaxation and stress-reducing therapies – presumably because people tend to clench their jaw when they are stressed, or because stress makes pain worse.

Splints or ‘bite guards’ are sometimes suggested.. These cover the teeth at night to reduce clenching of the jaw, and can be made by dentists. There is no definite evidence from research trials that they work, but some people say they find the splints helpful.

Tablets or medicines

Painkillers such as paracetamol, ibuprofen or codeine can help. If these are not enough, muscle relaxants or a small dose of a medicine called a ‘tricyclic antidepressant’ can give added pain relief.

Exercises or physiotherapy

Jaw exercises and physiotherapy can help the jaw muscles to work better so that there is less strain on the jaw joint area. There is information about exercises from the further information section below.

Treatment of other conditions

If there is an underlying condition, for example, a type of arthritis which is contributing to the TMJ disorder, this may need treating in its own right.

Injections or surgery

• An injection of steroid into the joint may help, when symptoms are due to inflammation in the joint.
• If the jaw muscles are overactive to a severe degree (such as with a movement disorder), an injection of botulinum toxin can reduce symptoms. There is debate about how effective this treatment is.
• For a very few patients, surgery to the jaw joint may be suggested. Various different operations can be done, depending on the individual situation.

What is the outlook for TMJ disorders?

Generally the outlook is good. Most TMJ disorders improve over time and do not get worse. It is very rare to get any complications with this condition. Some people do have symptoms that last longer or recur, but even these can usually be improved with the treatments described above. Most people do not need injections or surgery and will get better with simple treatments and time.

Further information

A leaflet with self-help advice and exercises for TMJ disorders, written by Norwich hospital ENT department, is available on: www.nnuh.nhs.uk/docs%5Cleaflets%5C392.pdf