Achieving improved visualization of the temporomandibular joint condyle and fossa in the sagittal cephalogram and a pilot study of their relationships in habitual occlusion

Improved glenoid fossa and condyle visualization is achieved by adapting the Denar TMJ Orthoceph Slimline Cassette (Denar Corp., Anaheim, Calif.) to sagittal cephalometry. This cassette contains rare-earth intensifying screens to enhance the temporomandibular joint region. A plastic template of circles of varying diameters is positioned so that the appropriate circle size is tangent to the superior, anterior, and posterior borders of the glenoid fossa seen on the resultant radiograph. The planar geometric center of the glenoid fossa is then identified coincident with the center of the template circle. The condyle planar geometric center is similarly identified. The relationships of these centers with respect to each other is described by using a rectangular coordinate system with the origin at the glenoid fossa geometric center. The condyle center is further described as being in any one of four quadrant locations or concentric with the glenoid fossa geometric center. This method was then applied to 38 patients who were free of temporomandibular joint symptoms in a pilot study relating the condyle quadrant location with the dentition in habitual occlusion. Findings revealed 89% of the condyles were in any one of the four possible quadrants. Fifty-three percent of the condyles were located in a downward and forward position (quadrant IV). Eleven percent of the condyle geometric centers were concentric with the glenoid fossa geometric center.