Variation of horizontal and vertical condylar angulation and its effect on TMJ tomographic imaging

Abstract

In this study, we examined the variation of the temporomandibular joint (TMJ) horizontal and vertical condylar angles in 1,143 patients who were referred for tomographic evaluation of the TMJ. Both angles showed a wide range of variation with the mean right and left horizontal con- dylar angles being 24.2 and 25.3 degrees, respectively. The mean right and left vertical condy- lar angles were found to be 3.3 and 4.5 degrees, respectively. The horizontal and vertical con- dylar angles were measured on a dry skull with a prominent morphologic landmark (os- teophyte). Corrected lateral cephalometric hypocycloidal tomograms were produced by com- pensation for the true horizontal and vertical condylar angles, and by varying each angle +2, -2, or +4, -A degrees from the true measured angles. It was found that a slight variation of +2 or -2 degrees in either the horizontal or vertical condylar angles would affect the shape, size and anatomic relationships of the bony components of the TMJ. These results demonstrate the need for individual compensation of the horizontal and vertical condylar angles to obtain high quality diagnostic tomographic images of the TMJ.