TMJ (temporomandibular joint) disorders are a family of problems related to the joint between the temporal bone of your skull and your mandible. Your TMJ is also known as your jaw joint.
If you have pain in front of your ear or on the side of your face, if have had your jaw lock open or closed, or if you have regular headaches, your TMJ’s may be part of the problem.
A “clicking” sound when opening and closing may also signal a problem. These symptoms occur if the position of your teeth is such that putting your teeth together causes a backward displacement of your lower jaw.
A piece of cartilage called a meniscus or articular disk normally exists between your upper and lower jaws to help cushion and position the mandible while chewing or swallowing.
A backward displacement of your jaw forces the meniscus forward. The click one hears when opening and closing is the meniscus “popping” on or off of the top of the mandible or condyle.
An intact meniscus is shaped like a bagel with a thin middle surrounded by a thicker outer edge and is attached to the condyle by ligaments. Repeated displacements of the meniscus flatten the back edge of the meniscus and stretch and tear the ligaments.
A deformed meniscus begins to look like a peach pit without a thicker outer edge to keep it centered over the condyle. Over time the damaged ligaments, like a worn-out rubber band, can no longer hold the meniscus in place.
When the meniscus begins to tear off of the condyle, it does so from the outside in (from lateral to medial) as the inside portion of the condyle is load-bearing and can better hold the meniscus in place.
The following is the progression from a healthy to a severely damaged joint described by Piper.
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- Stage I – no joint clicking, no subluxation with the articular cartilage staying between the condylar head and the articular surfaces during jaw movement.
- Stage II – intermittent joint clicking usually first thing in the morning. These patients often brux (grind their teeth) and develop nighttime headaches.
- Stage IIIa – chronic joint clicking. In this stage, the meniscus comes off the outside of the condyle (lateral pole) during jaw opening but reduces (returns to its proper position) upon closure. If the disc is relatively intact, the joint may be returned to Stage I status with proper treatment.
- Stage IIIb – no joint clicking. The meniscus is displaced from the lateral pole and does not reduce. The meniscus at the medial pole is intact. The patient may have episodes of jaw locking open or closed, however, this stage is usually pain-free.
- Stage IVa – chronic joint clicking. The meniscus is displaced from both medial and lateral poles but the medial portion of the meniscus reduces. The patient often experiences a limitation of movement, locking, and pain.
- Stage IVb – no joint clicking. The meniscus is displaced from the condyle at both poles and there is significant deformation of the disc. The condyle now functions against the retrodiscal attachment. Episodes of pain and locking are common.
- Stage Va – no joint clicking. In this acute stage, the condyle has perforated the retrodiscal tissue and the condyle rests on the skull base. This bone-on-bone contact is often very painful and these are the patients who often benefit from surgical intervention.
- Stage Vb – no joint clicking. This chronic stage often follows the acute stage and is relatively pain-free as the body has adapted. If a patient can endure the intensely painful Stage Va and arrive at this stage, surgery can be avoided. On occasion, the degeneration can follow but in many cases, the patient becomes stable.
Click here on the video to link to the classic Swedish study performed on dissected cadavers showing healthy TMJ’s and examples of TMJ’s of the internal derangements discussed above.
In summary, if the meniscus slips forward and stays forward, the mandible can get stuck in an open or closed position. When a meniscus no longer separates the skull base from the mandible, the condyle will function on the retrodiscal tissue made of ligaments, blood vessels, and nerve bundles that have not evolved to withstand the stress of loading.
At this point, patients usually begin to experience pain. Degeneration of the joint continues as the retrodiscal tissue is worn through and bone on bone contact results. Arthritis, bony degeneration, and severe changes in one’s bite can follow.
However, in some cases, TMJ disorders are not progressive. If you have some of the symptoms mentioned, it warrants further investigation, however, whether or not to treat the condition depends on factors unique to each individual.
What causes a TMJ Disorder?
As described by Howard, the causes are the following:
- Microtrauma such as repetitive strain from playing a wind instrument, a violin, singing, fingernail biting, scuba diving, snorkeling, and swimming.
Macrotrauma from an external blow as is experienced in an automobile accident, falls, cervical traction, sports injury, intubation, prolonged mouth opening, tooth extraction, and wearing a neck brace.
Ligament laxity (hypermobility) from hormonal variation, Breighton’s syndrome.
- Stress-induced parafunction such as tooth clenching, grinding or tapping.
- Sleep-induced bruxism is also known as involuntary nocturnal tooth grinding.
- Restrictive anterior bite position (upper front teeth that do not allow the lower jaw to position itself forward enough) as is seen in a deep bite, retruded upper incisors, or mandibular skeletal hyperplasia.
- Loss of posterior tooth. Missing or extracting molar (back) teeth without replacement.
- Excessive horizontal overjet (upper front teeth that are more than 6mm away from lower front teeth).
Developmental of congenital abnormal condylar forms such as is seen in a bidif condyle, condylar hyperplasia, or tumors.
Systemic inflammatory and metabolic polyarthritis including rheumatoid arthritis, juvenile idiopathic arthritis, scleroderma, psoriatic arthritis, ankylosing spondylitis, Reiter syndrome, systemic lupus erythematosus, and gout.
Infectious arthritis such as Lyme disease, sexually transmitted disease, gonococcal arthritis, and Chlamydia trachomatis.
Central nervous system-mediated maxillofacial movement disorders and palsy including hypokinesia such as Parkinson’s disease and muscular dystrophy, hyperkinesias such as tardive dyskinesia, dystonia, chorea, and myoclonus, and palsies such as cerebral palsy and facial palsy.
What About Bite Correction Or Surgery?
Surgical options such as arthroscopy and open joint repair restructuring are sometimes needed but are reserved for severe cases. Dr.Van Stralen always considers conservative treatment modes first.
TMJ surgery is the last option and is only considered if the jaw is painful and does not respond to any other treatment.