The temporomandibular joint (TMJ) is the small joint in front of the ear where the lower jaw fits in to the base of the skull. Between the top part of the jaw (the condyle) and the base of the skull (fossa) is a specialized disk similar to the meniscus of the knee. This joint allows people to open and close their mouth. Surrounding the joint are a number of muscles that facilitate opening and closing of the mouth.
TMJ disorders are not uncommon and can present with a variety of symptoms such as ear pain, headaches, limitation in the ability to open the mouth, changes in the bite, and increasing space in-between the front teeth of the upper and lower jaw.
One of the most common complaints about the TMJ is popping and clicking within the jaw joint. This is caused by the disk (meniscus) in the middle of the joint being positioned in front of the top part of the lower jaw (the condyle). The popping or clicking occurs when the disk is positioned in front of the condyle and on opening the mouth, the condyle slides on to the disk resulting in the noise. This positioning of the disk is more of an irregularity in anatomy than true bad positioning as it is found in almost 40% of humans. The time when this position becomes difficult is when it causes restriction of motion of the jaw, pain, or inflammation. In these cases, it is often self-alleviating with time, but there are several tactics used by surgeons to help treat this condition when it becomes pathologic. Typically surgeons begin with conservative therapy, medical management, sometimes splint therapy, physical therapy, and in only 10-15% of patients require surgical intervention.
The joint can also develop arthritis which can lead to a hole in the disk. This can cause a grating or grinding sound with opening and closing and can range in symptoms from just noise to pain and limitation of opening. This is also treated conservatively as mentioned above and rarely is cause for surgery.
In some patients, trauma, osteoarthritis, rheumatoid arthritis, or other conditions can cause severe restriction of movement of the joint. In these cases, the jaw joint can fuse with either scar tissue or a bridge of bone can form between the jaw and base of skull. This would necessitate surgical intervention to repair, however the condition is quite rare.
The most common problem and what people most commonly refer to as "TMJ" is an inflammation and spasm of the muscles that surround the jaw joint and facilitate opening and closing referred to as myofascial pain. This is often caused by grinding of the teeth at night, or clenching of the jaw during the day. The clenching and grinding has many factors and can be related to stress, medication, ergonomics, habits such as chewing gum, jaw injuries, how the teeth fit together, or a host of other causes that are not yet identified.
This spasm can lead to headaches, restriction of motion, severe and diffuse jaw pain, a shift in the bite, as well as back, and neck pain. It can also lead to inflammation within the jaw joint itself which serves to confuse the clinical picture. Due to the inflammation and muscle spasm, the mainstay of treatment is anti-inflammatory medication, muscle relaxing techniques, heat, rest, and typically a muscle relaxant. In people who are reluctant to try these treatments and continue to have significant pain, headaches/migraines, or other adverse effects to their daily life, can often get relief from BOTOX® in to the areas of muscle spasm.