The temporomandibular joint (TMJ) is a unique joint that consists of the condylar process of the mandible, temporal fossa, articular disc, and joint capsule. Fusion of the condylar head to the glenoid fossa will cause partial or total loss of mobility of the TMJ. This lack of movement, or ankylosis, can occur due to bony, fibrous, or fibro-osseous adhesions. Ankylosis of the temporomandibular joint is a permanent constriction of the jaws, and usually the maximum mouth opening will be less than 30mm, causing difficulties with mastication, speaking and oral hygiene, as well as influencing mandibular growth, and normal life activities.
The most common etiology of TMJ ankylosis is macrotrauma, such as a condylar fracture, but other causes may be found, including myositis ossificans, osteochondroma, rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, systemic lupus erythematosus, radiotherapy or surgical treatment of TMJ, infection, or congenital diseases.
Classification of ankylosis is usually centered on the radiographic extent of the ankylotic mass.
Xia et al. (2019) classifies the TMJA by types:
The onset of disease usually occurs in early childhood. Generally, the formation of bony ankylosis takes a long time, ranging from several months to decades after the occurrence of injury. A progressive reduction in jaw movement is the main clinical presentation. Bony ankylosis is characterized by radiographic evidence of bone proliferation with marked deflection to the affected side and marked limited laterotrusion to the contralateral side. The condition is not usually associated with pain. This disorder is characterized by the restriction of mandibular movements, resulting in difficulties in chewing, speech impairment, facial deformity, airway compromise, and psychosocial problems, especially in younger individuals.
Four main surgical techniques are currently advocated in the treatment of TMJA:
To prevent relapse after treatment, patients should undergo early and rigorous physiotherapy for at least 6 months after the surgery. Several techniques and appliances have been used for the maintenance of postsurgical outcome, such as stacked tongue depressors, interocclusal splints, commercial or custom-made devices, wedge exercisers, elastic traction, and hydraulic passive motion devices.
RCD/TMD classified TMJA as: hypomobility disorders other than disc disorders (ICD-10 M26.61; ICD-9 524.61)
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