D I S O R D E R S
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES National Institutes of Health
What Is the temporomandIbular JoInt? What are tmJ dIsorders? What Causes tmJ dIsorders? What are the sIgns and symptoms? hoW are tmJ dIsorders dIagnosed? hoW are tmJ dIsorders treated? If you thInk you have a tmJ dIsorder... researCh hope for the future
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Temporomandibular joint and muscle disorders, commonly called “TMJ,” are a group of conditions that cause pain and dysfunction in the jaw joint and the muscles that control jaw movement. We don’t know for certain how many people have TMJ disorders, but some estimates suggest that over 10 million Americans are affected. The condition appears to be more common in women than men. For most people,pain in the area of the jaw joint or muscles does not signal a serious problem. Generally, discomfort from these conditions is occasional and temporary, often occurring in cycles. The pain eventually goes away with little or no treatment. Some people, however, develop significant, long-term symptoms. If you have questions about TMJ disorders, you are not alone. Researchers, too, are looking foranswers to what causes these conditions and what are the best treatments. Until we have scientific evidence for safe and effective treatments, it’s important to avoid, when possible, procedures that can cause permanent changes in your bite or jaw. This booklet provides information you should know if you have been told by a dentist or physician that you have a TMJ disorder.
WhaT IS ThETEMpOROManDIbulaR JOInT?
The temporomandibular joint connects the lower jaw, called the mandible, to the bone at the side of the head—the temporal bone. If you place your fingers just in front of your ears and open your mouth, you can feel the joints. Because these joints are flexible, the jaw can move smoothly up and down and side to side, enabling us to talk, chew and yawn. Muscles attached to andsurrounding the jaw joint control its position and movement. When we open our mouths, the rounded ends of the lower jaw, called condyles, glide along the joint socket of the temporal bone. The condyles slide back to their original position when we close our mouths. To keep this motion smooth, a soft disc lies between the condyle and the temporal bone. This disc absorbs shocks to the jaw joint fromchewing and other movements. The temporomandibular joint is different from the body’s other joints. The combination of hinge and sliding motions makes this joint among the most complicated in the body. Also, the tissues that make up the temporomandibular joint differ from other loadbearing joints, like the knee or hip. Because of its complex movement and unique makeup, the jaw joint and itscontrolling muscles can pose a tremendous challenge to both patients and health care providers when problems arise.
Temporal muscle covering temporal bone
Masseter muscle Mandible
WhaT aRE TMJ DISORDERS?
Disorders of the jaw joint and chewing muscles—and how people respond to them— vary widely. Researchers generally agree that the conditions fall into three maincategories: 1 Myofascial pain, the most common temporomandibular disorder, involves discomfort or pain in the muscles that control jaw function. 2 Internal derangement of the joint involves a displaced disc, dislocated jaw, or injury to the condyle. 3 Arthritis refers to a group of degenerative/ inflammatory joint disorders that can affect the temporomandibular joint. A person may have one or more ofthese conditions at the same time. Some people have other health problems that co-exist with TMJ disorders, such as chronic fatigue syndrome, sleep disturbances or fibromyalgia, a painful condition that affects muscles and other soft tissues throughout the body. It is not known whether these disorders share a common cause.
People who have a rheumatic disease, such as rheumatoid arthritis,...