Clinical significance

Painedit

Temporomandibular joint pain is generally due to one of four reasons.

• Myofascial pain dysfunction syndrome, primarily involving the muscles of mastication. This is the most common cause.
• Internal derangements, an abnormal relationship of the disc to any of the other components of the joint. Disc displacement is an example of internal derangement.
• Osteoarthritis of the temporomandibular joint, a degenerative joint disease of the articular surfaces.
• Temporal arteritis, for which it is considered a reliable diagnostic criteria

Pain or dysfunction of the temporomandibular joint (TMJ) is sometimes referred to as temporomandibular joint dysfunction or temporomandibular joint disorder (TMD). This term is used to refer to a group of problems involving the temporomandibular joints and the muscles, tendons, ligaments, blood vessels, and other tissues associated with them.

Although rare, other pathologic conditions may also affect the function of temporomandibular joints, causing pain and swelling. These conditions include chondrosarcoma, osteosarcoma, giant cell tumor, and aneurysmal bone cyst.

Examinationedit

The temporomandibular joints can be felt in front of or within the external acoustic meatus during movements of the mandible. Auscultation of the joint can also be performed.

Disc displacementedit

The most common disorder of a temporomandibular joint is disc displacement. In essence, this is when the articular disc, attached anteriorly to the superior head of the lateral pterygoid muscle and posteriorly to the retrodiscal tissue, moves out from between the condyle and the fossa, so that the mandible and temporal bone contact is made on something other than the articular disc. This, as explained above, is usually very painful, because unlike these adjacent tissues, the central portion of the disc contains no sensory innervation.

In most instances of disorder, the disc is displaced anteriorly upon translation, or the anterior and inferior sliding motion of the condyle forward within the fossa and down the articular eminence. On opening, a "pop" or "click" can sometimes be heard and usually felt also, indicating the condyle is moving back onto the disk, known as "reducing the joint" (disc displacement with reduction). Upon closing, the condyle will slide off the back of the disc, hence another "click" or "pop" at which point the condyle is posterior to the disc. Upon clenching, the condyle compresses the bilaminar area, and the nerves, arteries and veins against the temporal fossa, causing pain and inflammation.

In disc displacement without reduction the disc stays anterior to the condylar head upon opening. Mouth opening is limited and there is no "pop" or "click" sound on opening.

Congenital disordersedit

• Aplasia of mandible or cranial bone
• Hypoplasia of mandible or cranial bone
• Hyperplasia of mandible or cranial bone
• Dysplasia abnormal tissue development

Traumatic disordersedit

• Mandibular dislocation
• Fracture
• Subluxation

Inflammatory disordersedit

• Synovitis
• Capsulitis
• Myositis

Degenerative disordersedit

• Osteoarthritis
• Rheumatoid arthritis
• Juvenile idiopathic arthritis

Idiopathic disordersedit

• Temporomandibular disorder (TMD, also termed "temporomandibular joint pain-dysfunction syndrome") is pain and dysfunction of the TMJ and the muscles of mastication (the muscles that move the jaw). TMD does not fit neatly into any one etiologic category since the pathophysiology is poorly understood and it represents a range of distinct disorders with multifactorial etiology. TMD accounts for the majority of pathology of the TMJ, and it is the second most frequent cause of orofacial pain after dental pain (i.e. toothache).
• Fibromyalgia