Introduction
TMJ is composed of a small disc of cartilage cushioned between the mandibular condyle (at the upper end of the jawbone) and the temporal bone of the skull. Fibrous tissue and ligaments also occupy this space. Painful and limited jaw movement occurs after inflammation, disc displacement and trauma to the TMJ. (1)
Stressed individuals who clench and grind their teeth or who have difficulty sleeping increase the risk of TMJ. Sometimes the cause of TMJ is unclear and diagnostic studies are needed to make the diagnosis. Part 1 discussed Muscle causes of TMJ. Part 2 emphasizes Joint Disorders.
Jaw joint disorders
Synovitis
It’s an inflammation of the lining (membrane) of the jaw joint causing pain in front of the ear made worse with jaw movement. Just as in the knee, this membrane secretes a lubricating fluid and when it becomes inflamed it secretes more fluid and the joint becomes warm, swollen and tender.
Displaced Jaw
About 50% of people have displacement of the small disc of cartilage out of the socket of the temporal bone that can ‘click’ back into its normal position with no need for treatment. When the cartilage is out of position and cannot be repositioned, the jaw becomes locked (‘locked jaw’). Usually, the pain and dysfunction can manually be corrected with jaw manipulation and medication. (2) The upper part of the jaw (the condyle) can be displaced out of position after a person bites into a sandwich or yawns. This is a painful disorder, where the patient is stuck with his mouth open. Manual manipulation of the condyle is an approach used to correct this problem.
Fractured Condyle
The round upper end of the jaw bone is the condyle. Condylar fractures are usually secondary to an altercation and a direct blow to the chin. The patient has pain and limited mobility of the mandible. Often there is accumulation of blood in the TMJ leading to adhesions, fibrosis and ankylosis of the jaw joint.
Ankylosis
Ankylosis is a stiffness or immobility of a joint or bone rigidity. Fibrous Ankylosis is the proliferation of fibrous, threadlike tissue that occupies the jaw joint severely limiting a patient’s ability to open the mouth. Bony ankylosis is the fusion of the bones of the jaw joint resulting in immobility of the TMJ. Both of these conditions have been associated with trauma to the TMJ.
Arthritis
Osteoarthritis is a non-inflammatory degenerative joint disease that grinds down the lining and cartilage of the jaw joint. Rheumatoid arthritis is an autoimmune disease that affects the jaw joint. Both of these arthritic conditions can cause pain, dysfunction and crepitus, a crackling sound with movement of the jaw. There are other arthritic conditions that can damage the TMJ.
Tumors
Benign and malignant tumors can cause symptoms that suggest TMJ. The patient and doctor need to be alert to this possibility in patients with TMJ problems.
Diagnosis
Normal mouth opening corresponds closely to your ability to place three fingers (index, middle and ring) in the mouth, one on tip of the other up to the first joint. Muscle disorders, osteoarthritis, joint complications and trauma frequently limit joint movement. These disorders can occur alone or in combination but one has to be alert to other general health problems that masquerade as TMJ; e.g. Fibromyalagia, Tumors. (1) In other words, your symptoms may not be the real cause of TMJ. Be concerned if you have pain unrelated to jaw movement, swollen lymph glands, numbness or treatments for TMJ that do not work. (3)
Often a good history of the problem and a focused physical examination of the patient are all that’s needed to make an accurate diagnosis. At other times, laboratory studies or imaging studies such as panoramic X-rays, MRI or CT scan are necessary to make the diagnosis.
Since more women than men have the problem, studies have been done that suggest a linkage among estrogen, pain and joint dysfunction. Ongoing research and technical advances continue to help doctors in the diagnosis and treatment of TMJ.
A YELLOW LIGHT… Bear in mind that TMJ pain is often moderate and goes away on its own. In less than five per cent of the time, it is necessary for you to make an appointment to see your doctor because of a sign or symptom of TMJ. (1) Of course, do not hesitate to see your Dentist, Oral Surgeon or ENT specialist if you have TMJ pain and dysfunction which is persistent. Remember to seek a second opinion if a doctor suggests operating on the Temporomandibular joint.
Part 3 shall deal with Treatments for TMJ.
References
- Goddard, Greg DDS; Temporomandibular Disorders; Diagnosis & Treatment; McGraw Hill.
- Klasser Gary, DMD, et al.; How to Manage “Closed Lock” Disc Displacement; Sept. 26, 2014.
- Kweawala, Cyrus, Newslands, Carrie; Oral and Maxillofacial Surgery; Oxford University Press.