[Internal derangement of the temporomandibular joint].

Internal Derangement is one of the most common disorders of the Temporomandibular joint. It is defined as an abnormal anatomical relationship between the discus articularis and the other structures of the temporomandibular joint. More than 2/3 of patients with clinical symptoms of the temporomandibular joint have an internal derangement. The most frequent finding in internal derangement is an anterior dislocation of the disc with reduction after mouth opening. In more severe cases a complete anterior dislocation is found without reduction of the disc. Internal derangement is a risk factor for developing osteoarthritis with remodeling of the condylus and the fossa mandibularis. The most important modalities of radiologic diagnosis are arthrography, CT and MRI. The diagnosis of craniofacial dysfunction has been improved dramatically by modern imaging techniques, which have become essential tools for primary diagnostic and evaluation after conservative or surgical therapy. MRI has become the gold standard.