Temporomandibular Joint Disorders

What are temporomandibular joint disorders?

Temporomandibular joint disorders are problems which affect the jaw joint.

The jaw joint is located just in front of the ear canal, and it joins the jaw bone (mandible) to the skull near to the temple. The jaw joint is also called the temporomandibular joint or 'TMJ'. Problems affecting this joint are usually known as 'TMJ disorders'. However, there are various other medical terms for for this condition. For example, 'TMJ dysfunction', 'TMJ pain' and 'myofascial pain disorder'.

Understanding the jaw joint

A joint is where two bones meet. Joints allow movement and flexibility between two bones. The jaw joint allows movement between the mandible (jaw bone) and the skull. Muscles attached to the skull and jawbone cause the jaw bone to move as the mouth is opened and closed.

Inside the jaw joint, there is a smooth material called cartilage, covering part of the bones. There is also a cartilage disc within the joint. The joint is lubricated by fluid called synovial fluid.

What are the symptoms of TMJ disorders?

• Pain in the joint area or nearby. The pain is usually located 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.
• Clicks or noises can sometimes be heard coming from the jaw joint when you chew or move your mouth. These noises can be normal, so they are only relevant if you have other symptoms in the joint such as pain or reduced movement.
• 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).

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?

In general, TMJ disorders are thought to have a 'multifactorial' cause, meaning that there are usually a number of factors contributing to the cause. These factors can be grouped into two types: problems linked to the muscles working the joint, and problems inside the joint itself. The muscle problems are the most common type, particularly for younger people.

Problems with the muscles may be caused by:

• 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.
• Increased sensitivity 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 may be caused by:

• Wear and tear to the inside of the joint, for example, wear and tear to the cartilage. Sometimes this is due to a type of arthritis called osteoarthritis. This problem tends to affect older rather than younger people.
• Certain types of arthritis. Arthritis means inflammation in a joint. There are different kinds of arthritis. For example, rheumatoid arthritis and gout are both types of arthritis which may affect various joints in the body, and they can sometimes affect the jaw joint.
• Injury to the TMJ or to its cartilage disc can cause TMJ pain.

How are TMJ disorders diagnosed?

Often, the diagnosis is made on the basis of your symptoms and a doctor's examination. In many cases, no tests are necessary, if you are healthy and have symptoms that are typical of a TMJ disorder.

Possible tests are:

• Blood tests may be helpful to look for signs of inflammation, or to rule out other causes of pain in that area.
• An MRI scan can be used to give a detailed picture of the joint. X-rays are another option, but are used less often now that MRI scans are available.
• A 'diagnostic nerve block' may help to clarify whether the pain is coming from the joint or the muscles. Local anaesthetic is injected near the nerve which goes to the jaw joint. If this relieves the pain, then it suggests that the pain comes from the joint itself.
• Arthroscopy (using a fibreoptic device to look inside the joint) may be used if other tests do not show the cause of the pain.

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 find them helpful.

Medication

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.

Physiotherapy

Physiotherapy treatments such as ultrasound, and gentle jaw exercises can be helpful.

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.
• Arthroscopy (inserting a fibreoptic device inside the joint) can be used for some types of treatment or surgery to the joint.
• For a very few patients, surgical repair of the 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

The TMJ Association

A patient organisation based in the USA. Their website provides information on TMJ disorders, including self-care advice for patients with TMJ pain.
Web: www.tmj.org

References

• Dimitroulis G; Temporomandibular disorders: a clinical update. BMJ. 1998 Jul 18;317(7152):190-4.
• Buescher JJ; Temporomandibular joint disorders. Am Fam Physician. 2007 Nov 15;76(10):1477-82. [abstract]
• The TMJ Association Ltd; A patient organization based in U.S.A. Provides information on TMJ disorders.
• Scrivani SJ, Keith DA, Kaban LB; Temporomandibular disorders. N Engl J Med. 2008 Dec 18;359(25):2693-705.
• Ault J, Berman SA. Temporomandibular Disorders. eMedicine, March 2009.
• Clark GT, Stiles A, Lockerman LZ, et al; A critical review of the use of botulinum toxin in orofacial pain disorders. Dent Clin North Am. 2007 Jan;51(1):245-61, ix. [abstract]