Cephalometric keys to internal derangement of temporomandibular joint in women with Class II malocclusions.

The aim of this study was to find cephalometric keys to provide information on the progression of temporomandibular internal derangement. The sample consisted of 58 women with Class II malocclusions. They were examined with routine lateral cephalograms and magnetic resonance imaging of the temporomandibular joint (TMJ) before orthodontic treatment. They were classified into 3 groups according to the results of the magnetic resonance imaging: normal disk position, disk displacement with reduction, and disk displacement without reduction. Thirty-four cephalometric variables regarding their pretreatment lateral cephalograms were analyzed by 1-way analysis of variance to evaluate the differences in the dentofacial morphology among the 3 groups. The results showed a decrease in posterior facial height, a decrease in ramus height, and backward rotation and retruded position of the mandible in the subjects with internal derangement of the TMJ. These changes were less severe in those with disk displacement with reduction and more severe as internal derangement progressed to disk displacement without reduction. The results suggest that internal derangement of the TMJ might induce dentofacial changes, and that some cephalometric variables can assist in identifying potential patients with internal derangement of the TMJ.