Clinical outcomes of Fränkel appliance therapy assessed with a counterpart analysis

To evaluate whether the Fränkel Regulator-II (FR-II) induced mandibular growth rotations relative to the nasomaxilla and the middle cranial fossae, cephalometric changes in 28 treated Brazilian children were compared with changes in 28 untreated Class II children and in 28 children with normal occlusion. According to Enlow's counterpart analysis, the 3 groups were not significantly different initially in ramus alignment or relative ramus vertical dimension. These jaw relationships were maintained in both untreated groups. In the treated group, all children had overjet reduction, with correction of the dental arch relationship in 26 of the 28, and there was a significant trend toward a more forward ramus alignment (P =.002) and increased ramus relative vertical dimension (P =.0002). These treatment-induced changes showed a negative correlation with ramus alignment; ie, greater improvement was more likely in children who had backward ramus alignment before treatment and whose Class II malocclusion had not already been intrinsically compensated. Changes in the treated children were similar to but greater than those in the normal children, and different from those in the untreated Class II group. The data suggest that studies of skeletal variations with counterpart analysis can show ramus remodeling compensations from treatment that are missed with conventional cephalometrics.