Differences between sliding mechanics with implant anchorage and straight-pull headgear and intermaxillary elastics in adults with bimaxillary protrusion

The lateral cephalograms of 28 adult orthodontic patients (3 males and 25 females; age, 24.9 +/- 5.0 years) who had an Angle Class I malocclusion with bimaxillary protrusion were selected. Group 1 (14 patients; 1 male and 13 females; age, 25.0 +/- 5.1 years) received sliding mechanics with implant anchorage and group 2 (14 patients; 2 males and 12 females; age, 24.8 +/- 5.1 years) a straight-pull headgear and intermaxillary elastics. Lateral cephalometric radiographs obtained before and after treatment were traced, 13 landmarks identified, and differences in the skeletal and dental changes compared between the groups. Wilcoxon's signed-rank test was used to determine changes within the treatment groups and a Mann-Whitney U-test to evaluate significant differences. More anchorage loss occurred at the maxillary posterior teeth in group 2 (2.1 mm) than in group 1 (0.1 mm). Closing rotation of the mandible occurred in group 1, while opening rotation of the mandible was observed in group 2. These results suggest that sliding mechanics with implant anchorage may provide absolute anchorage and could control mandibular rotation more than the conventional technique.