Evaluation of Articular Eminence Morphology and Inclination in TMJ Internal Derangement Patients with MRI Evaluación de la Morfología e Inclinación de la Eminencia Articular en Pacientes con Trastorno Interno de ATM con MRI

Articular eminence morphology and inclination are reported to be two predisposing factors for the internal derangement (ID). The purpose of this study is to investigate the relationship between the inclination and morphology of the articular eminence and ID. The study included 70 temporomandibular joints with ID in 35 patients: 51 joints had disc displacements with reduction (DDWR) and 19 joints had disc displacements without reduction (DDWOR). All subjects underwent bilateral high resolution magnetic resonance imaging scans which were performed in the sagittal and coronal planes with mouths closed and opened. Articular eminence morphology was characterized as box, sigmoid, flattened, or deformed. Articular eminence inclination was measured at three positions: steep (from 60° to 90°), moderate (from 30° to 60°) and shallow (from 15° to 30°). The images were divided into two; DDWR and DDWOR, and these two criteria were compared. The images of the two groups were compared; while flattened form was occurred with the highest incidence in the DDWOR group, sigmoid form was the most frequent in the DDWR group and articular eminence inclination was found steeper than it was for the DDWOR group. The steepness of the articular eminence may not have a predisposing effect on the development of disc displacements.