Morphologic and Positional Assessment of TMJ in Facial Assymetry Patient

Objectives: To evaluate the morphometrics of the disc status in patients with facial asymmetry (FA) and the possible relationships between internal derangement (ID) and FA. Methods: Seventy-four TMJ MRIs of 37 patients with FA were selected. There were 10 males and 27 females and the ages range from 12 to 44 years old, with a mean age of 21.4-year-old, Sagittal and coronal TMJ MRIs were obtained at maximum intercuspation and maximum mouth-opening position. Disc displacement (DD) types, including partial anterior, anterior, rotational and sideways DD, were recorded. The disc configuration, position, disc translation and rotation were also investigated on the MRI tracings. The TMJs were grouped into normal, anterior disc displacement with reduction (ADDR), or without reduction (ADDNR). Patients were divided into bilateral normal, unilateral ID and bilateral ID groups. Results: ADD, especially rotational ADD more frequently occurred in the shifted side, while normal disc position was observed mainly in the opposite side (P<0.01). Around 70% patients showed unilateral or bilateral IDs. The disc of the shifted side showed significantly deformed configuration and inferior-anterior disc position. However, the disc of the contrary side showed hypermobility in the vertical direction during jaw opening movement. Conclusions: In FA patients, the ADD types are related to disc shape, disc inclination, disc translation angle, vertically translation distance and disc rotation angle.