Comparison between two bone anchored force systems for correction of skeletal Class II malocclusion in growing patients: a randomized controlled clinical trial, part 1: short-term skeletal changes.

Objectives: To compare the treatment effects of pushing or pulling force mechanics applied to bimaxillary miniplates with those of deferred treatment control patients to evaluate mandibular skeletal growth changes in growing patients with skeletal Class II malocclusion due to mandibular deficiency.

Materials and methods: Thirty-nine patients (24 males, 15 females; mean age = 11.59 ± 0.56 years) were equally and randomly assigned to one of three groups: Group A, skeletally anchored fixed-functional appliance (pushing mechanics); Group B, skeletally anchored Class II spring (pulling mechanics); and Group C, deferred treatment skeletal Class II control patients. Pretreatment and posttreatment cone-beam computed tomography scans were used for assessment of measurements (time interval: 11.52 ± 0.32, 11.53 ± 0.31, and 9.63 ± 0.22 months for groups A, B, and C, respectively).

Results: Relative to the control group, both intervention groups showed significant increases in effective mandibular length (Co-Gn), with mean differences of 5.08 ± 2.25 mm in Group A, and 3.83 ± 2.79 mm in Group B. A significant improvement in the sagittal relationship was observed in both groups, with reductions in ANB angle by 4.31° in Group A, and 5.5° in Group B. The mandibular plane angle was increased significantly in Group B by 1.83 ± 0.72°.

Conclusion: Mandibular growth was enhanced using either pushing or pulling skeletally anchored force mechanics. The use of pulling force mechanics, specifically, was associated with increases in lower facial height.