3D soft-tissue evaluation of a Class III treatment with rapid maxillary expander and face mask in pre-pubertal phase-A retrospective cohort study.

Objectives: The aim of this prospective controlled study was to evaluate the effectiveness of the rapid maxillary expander (RME) and face mask treatment using three-dimensional soft-tissue facial characteristics of pre-pubertal Class III children.

Setting And Sample Population: CLIII and non-CLIII groups, both of 32 white children aged 6-8 years participated.

Material And Methods: Facial surface images were obtained using stereophotogrammetry at T0 and T1 and were superimposed. Landmark-based and surface-based facial parameters were measured, and group differences were quantified (ANOVA; P ≥ .05).

Results: CLIII children had less mid-face prominence, shorter lower facial height and protruded mandible when compared to non-CLIII children at T0. At T1, the differences between the groups were not statistically significant, indicating successful correction. After the RME/face mask treatment, the n-sn and sn-pg distances increased by 1.5 mm and 2.2 mm, respectively. The distance from sn to the n-pg line increased by 1 mm, the n-sn-pg angle decreased by almost 2°. Pogonion moved downward by 2.5 mm and posteriorly by 3 mm. The surface-based measurements between the groups after treatment showed anterior movement in the mid-face region and the upper lip region. The lower lip and chin region moved posteriorly in the CLIII group and anteriorly in the non-CLIII group.

Conclusions: After RME/face mask treatment, the lower facial height increased, the maxilla moved anteriorly, and the mandible moved posteriorly. Consequently, CLIII children reached the respective values of the non-CLIII children, indicating a harmonious facial appearance of CLIII children. The results have been obtained using non-invasive technique.