The treatment effect of mandibular protrusive appliances on the glenoid fossa for Class II correction.

A study was undertaken to determine the contribution of glenoid fossa modification in the correction of skeletal Class II malocclusions. Individually corrected lateral tomograms of 35 patients (18 boys and 17 girls) between the ages of 7.96 and 15.06 years were used. The subjects were selected on the basis of the criteria that they were suitable for treatment with a mandibular protrusive appliance (activator). The mean duration of activator treatment was 1.33 years. Tomograms were taken on a pre- and posttreatment basis. The tomograms were scanned and digitized on screen using a common software program. Points were located on each tomogram and specific linear measurements were used to evaluate any changes in glenoid fossa morphology. Paired t-tests were applied for the left and right sides separately and between the before and after treatment measurements. Paired t-tests were also applied between the left and right sides to test for any difference between the sides. The results of this study demonstrated that there are no positive radiographically depictable contributions from glenoid fossa modification for the correction of skeletal Class II malocclusions treated with mandibular protrusive appliances (activators). In addition, no statistically significant differences were found between right and left sides denoting relative symmetry. It is concluded that, contrary to animal research and magnetic resonance findings, it seems possible that glenoid fossa modeling is not induced by mandibular protrusive appliances during treatment of skeletal Class II problems.