Disorders of the jaw joints and chewing muscles can come in a whole range of types, as can the individual’s response. Clinicians generally agree that the conditions fall into three main categories:
- Myofascial or muscle pain, the most common temporo-mandibular disorder, involves discomfort or pain in the muscles that control jaw function
- Internal derangement of the joint can involve a displaced disc, dislocated jaw, or injury to the condyle
- Arthritis refers to a group of degenerative/inflammatory joint disorders that can affect the temporo-mandibular joint
A person may have one or more of these 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 but there may be a link.
People who have a rheumatic disease, such as rheumatoid arthritis, may develop TMJ disease as a secondary condition. Rheumatic diseases refer to a large group of disorders that cause pain, inflammation, and stiffness in the joints, muscles, and bone.
Both rheumatoid arthritis and some TMJ disorders involve inflammation of the tissues which line the joints. The exact relationship between these conditions is not known.