The temporo-mandibular joint is the jaw joint where the mandible (lower jaw) joins the temporal bone of the skull, in front of the ear on each side of the head. The TMJ acts as a hinge, and allows your mouth to open and close and move from side to side when chewing. Each time you chew, talk or yawn you move the TMJ, making it one of the most used of all the joints of the body.
You can locate the joint by putting your finger in front of your ear and pressing firmly while opening your mouth. The movement you feel is occurring at the TMJ.
When you bite down, you not only put force on the object between your teeth but also on the TMJ. To prevent too much wear and tear from occurring in one spot within the joint space, the TMJ was designed to be a sliding joint, so that forces are distributed over a wider space. Joints are lined with cartilage which is slippery and rubbery and allows for smooth motion.
Some people suffer from disorders affecting one or both TMJs, muscles that are attached to the TMJ, and surrounding tissues. These often restrict jaw function or cause pain.
If you habitually clench, grit or grind your teeth, you increase the wear and tear on the cartilage lining of the joint. Many people grind their teeth while asleep (bruxism). Some people habitually chew on one side only – this is more likely if you have a tooth problem on one side, or if you had recent dental work or if your teeth or dentures do not fit together properly.
In each of the above situations, a faulty chewing pattern occurs that creates one focus of wear in the cartilage of the joint space. When this spot wears down beyond a comfortable level, pain occurs. This is known as TMJ dysfunction.
In addition, symptoms may arise from an injury to the jaw, or it may be degenerative diseases like osteoarthritis and rheumatoid arthritis.
Pain is a common symptom. This may be sharp and searing, occurring each time you chew, yawn or talk. The pain may be dull, constant or boring.
The pain can cause spasm in the adjacent muscles of the skull, face and jaw. Therefore, though the pain usually occurs over the joint, it can radiate elsewhere e.g. to the temple, cheek, lower jaw and teeth.
TMJ dysfunction also often causes pain in the ear. This may be associated with ringing in the ears (tinnitus), which can also occur when you clench your teeth together hard.
Sometimes a blocked feeling as if something is stuck in your ear occurs. Check with your doctor that there is no wax or fluid in the ear canal and avoid wiggling the jaw to try and clear the ear.
Other symptoms include popping, clicking or grinding sounds when the jaw is opened. There may be a limited range of jaw movement. Dislocation (“locking”) can occur with the jaws wide open, or you may not be able to open your mouth.
Mild cases will often respond to simple remedies:
Chew evenly, using left and right sides
When chewing, keep your lower jaw as far back as possible to avoid stress on the TMJ. Avoid extreme movement of the jaw
Do not clench, grind or grit your teeth.
Ensure that your dentures fit well
Avoid chewing gum or hard foods
Apply a heating pad for ½ hour a day
Take simple painkillers e.g. Paracetamol, or anti-inflammatories that your doctor prescribes.
If this does not resolve the problem, you may require further consultation with an oral surgeon or dentist. They will perform the necessary investigations e.g. Xrays, CT scans, and may prescribe an occlusal appliance (bite plate, splint or mouth guard) which helps to relax the muscles and take pressure off the TMJ. If necessary, surgery to the joint may be considered.