Soft tissue evaluation after maxillary protraction with RPE or with the ALT-RAMEC protocol : Acontrolled 3D study.

Abstract

To evaluate soft tissue changes following maxillary protraction with different expansion protocols using three-dimensional (3D) stereophotogrammetry. Pretreatment (T0) and postprotraction (T1) stereophotogrammetry and lateral cephalometric images of skeletal classIII patients were included in this retrospective study. In all, 32patients were treated either with acombination of rapid palatal expansion and facemask (RPE/FM; n = 16; mean age: 9.94 ± 0.68years) or with alternate rapid maxillary expansion and constriction together with afacemask (Alt-RAMEC/FM; n = 16; mean age: 9.74 ± 1.35years). As acontrol group16 untreated patients were recruited (mean age: 9.46 ± 0.8years). For superimpositioning of the 3D images taken at T0 and T1, the face was divided into defined regions and 3D and differences between the groups were evaluated using 3‑matic software (Materialise Europe, Leuven, Belgium). Cephalometric analyses were also performed. While the increases in the cephalometric parameters SNA and ANB were significantly greater in the treatment groups, the value for SNB also increased in the control group (p < 0.05). The results of the stereophotogrammetry analyses demonstrated that the mean changes in the RPE/FM and in the Alt-RAMEC/FM groups were significantly different for the midface compared to the control group (0.33 ± 0.26 mm, 0.3 ± 0.31 mm, 0.1 ± 0.18 mm). The maximum positive, negative, and mean changes were also significantly different between the treatment and control groups for the upper lip (p < 0.05). For the lower lip and the chin significant backward movements in the RPE/FM as well as in the Alt-RAMEC/FM group (-1.06 ± 1.26 mm, -0.68 ± 0.45 mm) were observed, while the control group (0.09 ± 0.53 mm) presented changes in the opposite direction. Regarding soft tissue changes, no significant differences were found between the RPE/FM and Alt-RAMEC/FM groups. Both treatment protocols improved the soft tissue profile due to aforward movement of the midface and the upper lip, and abackward movement of the lower lip and chin, compared to the control group.