Temporomandibular Joint Dysfunction
(TMJD · Jaw Pain)
In this condition factsheet:
The Facts on Temporomandibular Joint Dysfunction
The temporomandibular joint (TMJ) is one of the most complicated joints in your body. You have one on each side of your face, just in front of your ears, where the temporal bone of the skull connects to the lower jaw (mandible). Your TMJs open and close like a hinge and slide forward, backward, and from side to side. When you bite and chew, they sustain an enormous amount of pressure.
As with other joints, the surfaces of your TMJs are covered with cartilage. Like the knee joint, the two parts of the joint are separated by a small disc, or meniscus, that prevents the bones from rubbing against each other. Muscles that enable you to open and close your mouth also serve to stabilize these joints, which are located about one-half inch (1.25 cm) in front of each ear canal.
A range of problems can affect the TMJs and the muscles surrounding them. These problems usually occur between the ages of 20 and 50. Most often, the cause of TMJ is a combination of muscle tension, anatomical problems, and injury. Sometimes, there may be a psychological component as well.
Like all of your joints, your TMJ may develop osteoarthritis, rheumatoid arthritis, and other inflammatory conditions. In rare instances, tumours may develop in this area. But for most people, pain in the area of the TMJ isn't serious. Discomfort and pain may be temporary or chronic and often goes away with little or no treatment.
Causes of Temporomandibular Joint Dysfunction
In order for you to open your mouth and operate your jaw in the way that it should, your left and right TMJs must work in unison. If the movement of both of these joints isn't coordinated, the disc that separates your lower jaw from your skull can slip out of position, and problems will result. Dislocation of your TMJ may take place if your mouth is forced to open rapidly or too widely.
In addition, muscle pain and tightness around the jaw can often come from muscle overuse as a result of clenching or grinding the teeth (bruxism) brought on by psychological stress or overuse. Extreme jaw clenching can also lead to pain over the temples. This occurs because the muscles that control jaw movement are also attached to a nearby bone of your skull. Excessive gum chewing or forceful biting, such as cracking nuts in your teeth, may also strain the TMJs and cause pain.
Some additional and less common ways of developing temporomandibular joint problems include:
- ankylosis, which is loss of joint movement resulting from a fusion of bones within the joint or calcification of the ligaments around it
- arthritis
- certain inherited facial characteristics that produce misalignments
- congenital abnormalities where the top of the jawbone doesn't form or is
smaller than normal
- dental conditions such as a high filling, a tipped tooth, or teeth displaced due to earlier loss of other teeth
- developmental abnormalities such as in some children where the top of the jawbone may grow faster or for a longer time than normal. Congenital and developmental abnormalities are rare, but can cause facial deformities and misalignment of the upper and lower sets of teeth.
- hypermobility (looseness of the jaw), when the ligaments that hold the joint together become stretched
- internal derangement, where the disc inside the joint lies in front of its normal position
- structural abnormalities of the temporal joint
Symptoms and Complications of Temporomandibular Joint Dysfunction
There is an easy test you can do yourself to check whether you're able to open your jaw as much as you should. Most people can place the tips of their index, middle, and ring fingers held vertically in the space between the upper and lower front teeth without forcing. If your space is smaller, or if you experience pain, or a clicking or grinding noise when you try to open your mouth this far, you probably have temporomandibular joint problems.
Common symptoms of TMJ problems include:
- a clicking sound or grating sensation on opening the mouth or chewing
- dull aching pain in front of the ear
- headaches that don't respond to the usual medical treatment
- locking of the joint, making it difficult to open
- tenderness of the jaw muscles
The pain will often occur only on one side of the face, and sometimes the pain may seem to occur near the joint rather than in it. Pain and muscle tightness may be present after waking up in the morning or during and after stressful periods. These symptoms result from muscle spasms brought on by repeated muscle or tooth clenching and tooth grinding. Many people grind their teeth during their sleep and aren't even aware of it, and clenching and grinding is more forceful when a person is asleep than when they are awake.
