Skeletal class III treatment with mini-screw-assisted memory screw-facemask combination: A pilot study

Abstract

Background: The aim of this study was the evaluation of treatment outcomes after using mini-screw-assisted memory screw-facemask combination in early permanent dentition Class III malocclusion. Materials and Methods: Treatment of six subjects (mean age 11.5 ± 1.1 years) was investigated clinically and by using pre- and post-treatment cephalograms. An anchorage unit was prepared by placing two mini-screws just behind a line connecting the first premolars at the mesial contact point. With the memory expansion screw (500 g), two mini-screws were placed parallel to the occlusal plane to provide stable, four-point support for the appliance. Wire segments were added along the palatal surfaces of the buccal teeth, annealing the terminal ends and then bending the ends into hooks for attachment of reverse-pull facemask elastics. The memory screw was activated twice a day and the facemask was prescribed for 16 h wear, using ¼ inch, 400 g elastics (in total 800 g) extending crosswise from the lingual arms on the expander. Pre- and post-treatment differences were tested for statistical significance using paired t -test. Results: All appliances remained stable during treatment. Mean treatment was for 4.8 ± 1.5 months. There was a significant improvement in skeletal sagittal values: SNA, +2.6°; SNB, −1.4°; ANB, +4.0°; WITS appraisal, +4.6 mm; and overjet, +2.9 mm. In relation to A point, the upper first molars moved mesially about 0.9 mm. Conclusions: The mini-screw-assisted memory screw-facemask combination seems to be effective for skeletal Class III treatment in early permanent dentition.