STEEPNESS OF THE ARTICULAR EMINENCE IN THE TEMPOROMANDIBULAR-JOINT - TOMOGRAPHIC COMPARISON BETWEEN ASYMPTOMATIC VOLUNTEERS WITH NORMAL DISK POSITION AND PATIENTS WITH DISK DISPLACEMENT

Objective. A steep articular eminence has been proposed as one etiolog ic factor for the development of TMI disk displacement. The purpose of this study was to determine the steepness of the articular eminence i n asymptomatic volunteers with superior disk position and to compare i t with the articular eminence in patients with internal derangement. S tudy design. We investigated 34 asymptomatic volunteers and 71 patient s. The steepness of the articular eminence was determined on sagittall y corrected tomograms, and disk position was diagnosed by dual space a rthrotomography. Results. The results showed that the articular eminen ce was on the average steeper in the asymptomatic volunteers in the la teral (64.9 degrees), central (64.4 degrees), and medial (65.4 degrees ) sections of the joint than in the patients (56.1 degrees, 60.2 degre es, 58.9 degrees, respectively). When the comparison of the steepness of the eminence was based on the presence or absence of osseous change s in the form of remodeling or osteoarthrosis, no difference was found between the asymptomatic volunteers and the patients with disk displa cement but without such changes. The largest difference in the steepne ss of the eminence was found between the persons with osseous changes and those without. Conclusion. These findings contradict earlier studi es that have indicated a steep articular eminence to be one etiologic factor for the development of disk displacement. The results of this s tudy showed that the steepness of the articular eminence is decreased in the patients as a result of remodeling or degenerative changes of t he bone that are a result of the internal derangement.