Dentoskeletal effects of functional appliances vs bimaxillary surgery in hyperdivergent Class II patients

Abstract

To compare treatment outcomes of growing and nongrowing Class II patients characterized by mandibular retrusion and increased vertical dimension. Seventeen patients (mean age 9 years 5 months) were treated with a Bionator fabricated with posterior bite block and high-pull headgear, while 15 patients (mean age 23 years 6 months) received Le Fort I osteotomy for maxillary impaction and mandibular advancement. These groups were compared with 17 nontreated control subjects from the Bolton and Michigan growth studies. Lateral cephalograms taken for the functional group at T1 (initial records), T2 (completion of functional appliance treatment), and T3 (completion of comprehensive treatment) were compared with radiographs taken at T1 (initial records), T2 (immediate post surgery), and T3 (1 year post surgery) for the surgical patients. A null hypothesis of no difference in treatment outcomes between the functional and surgical groups was proposed. A mixed-design analysis of variance was used to compare changes within and between groups. Significance was set at P ≤ .002. In the functional appliance group, the mandible showed a more favorable growth direction and rotation. Both groups had stable results over time and finished treatment with similar cephalometric measurements. Both the functional appliances and orthognathic surgery resulted in similar dentoskeletal treatment changes. The control groups did not self correct either in the anteroposterior or vertical dimensions.