Comparison of Tooth-borne Versus Bone-anchored Protraction Facemask Treatment

Objectives: Objective: A retrospective study to compare the skeletal and dentoalveolar changes in patients treated with the tooth-borne and bone-anchored maxillary protraction appliances.
Methods: Methods: Twenty Class III patients (mean age 9.8±1.6) treated with tooth-borne maxillary expansion and protraction device and 20 patients (mean age 9.6±1.2) treated with the Hybrid-Hyrax bone-anchored device were included in the study. Lateral cephalograms were taken at the start and completion of maxillary protraction. A control group of Class III patients with no treatment was used to subtract changes due to growth to obtain the appliance effect. A custom cephalometric analysis based on variables described by Bjork and Pancherz was used to determine skeletal and dental changes. Data were analyzed using a one-way analysis of variance with p<0.05.
Results: Results: Significant differences were found between the two groups in 8 out of 37 cephalometric variables (p<.05). Subjects in the tooth-borne group had more proclination of maxillary incisors (1.5mm vs 0.1mm), increase in overjet correction (5.9mm vs 3.3mm) and molar relationship correction (2.8mm vs 1.0mm). Subjects in the bone-anchored group had less downward movement of the “Pt A” (-0.48mm vs 1.23mm), opening of the articulare angle (S-Ar-Goi, -0.14^o vs 4.34 ^o), and opening of the mandibular plane (FH-ML, 0.66 ^o vs 2.64 ^o).
Conclusions: Conclusion: These results suggest that the Hybrid-Hyrax bone-anchored appliance had better control on the vertical eruption of the molars and may serve as an alternative treatment for Class III patients with a hyperdivergent growth pattern.