Subluxation or hypermobility in the temporomandibular joint is defined as the clinical condition with repeated episodes of partial dislocation of the jaw. The temporomandibular joint is a complex joint exhibiting hinge movement. The upper portion of the joint composed of temporal bone which remains stationary while the lower portion formed by the condyle of the mandibles moves within the concavity.
Subluxation in simple words can be explained as slipping of the condyle from its socket. The condition may involve the temporomandibular joint on one or both the sides. It is a self-reducing incomplete dislocation of the jaw which generally follows stretching of the ligaments and the capsule surrounding the tempero-mandibular joint.
The condition can be unilateral or bilateral in nature. It is usually accompanied by a cracking noise caused by temporary locking of the condyle and immobilization of the jaws. It is a chronic disorder and the patient may complain of weakness in the joint while opening the mouth. Complete opening of the mouth is generally associated with pain.
The repeated attack of dislocation is common on prolonged mouth opening or stretching. Regular day to day activities such as yawning, singing, laughing or sleeping on one arm in bed can trigger the dislocation. After each subsequent attack of subluxation, there is further stretching of the joint capsule which aggravates the condition and leads to further recurrence.
The major cause of temporomandibular subluxation is injuries to the capsule surrounding the joint or the ligaments aiding in joint movements. . It is also seen in severe epilepsy, dystrophia myotonia and Ehlers-Danlos syndrome. Prolonged dental appointments with long continuous opening of mouth can be one of the triggering factors for temporomandibular subluxation.
Certain oral surgical procedures causing stretching of the ligaments that support the joint can lead to temporomandibular subluxation. It can also be a part of degenerative changes of osteoarthritis affecting the jaws. The condition may be associated with a history of trauma to the joint and surrounding structures. Psychiatric problems are also associated with tempormandibular joint subluxation.
The treatment can be conservative or surgery may be needed. The conservative treatment consists of inducing a sclerosing agent inside the joint capsule. The rationale behind the treatment is to cause shrinking or fibrotic changes within the capsule, which will limit the hypermobility of the joint. Generally used sclerosing agent is sodium psylliate or 5 percent intracaine in oil base. The injections may have to be repeated for every 2 to 3 weeks till fibrosis occurs.
Another non-surgical treatment method is intermaxillary fixation or limiting the oral opening by giving elastics. The total immobilization of jaws for 3 to 4 weeks provides rest to the joint. The major problem with intermaxillary fixation is the consumption of liquid diet for long duration. Surgical methods are used to correct the joint dysfunction.
These surgical procedures include creation of a mechanical block to the freely moving condyle by placement of a bone graft or direct restraint of the condyle. The surgical treatments also include creating a better muscle balance and capsule tightening procedures.