Facial soft tissue changes following maxillary skeletal expansion and protraction in growing patients with class III malocclusion: A randomized clinical trial.

Abstract

Objective: This study aims to assess and contrast the changes in facial soft tissue that occur in growing patients with Class III malocclusion after facemask maxillary protraction with a maxillary skeletal expander (MSE) versus a hybrid Hyrax.

Methods: In this randomized control clinical trial, 30 patients were randomly selected and allocated into three treatment groups: group 1: (n = 10; mean age 9.6 ± 0.84 years) control group; group 2: 10 patients (mean age 9.5 ± 0.97 years) were treated with the hybrid hyrax expander-facemask; group 3: 10 patients (mean age 9.9 ± 0.74 years) were treated with the MSE-facemask. Pre-, post-treatment, and observation period cephalometric and extraoral photographs were analyzed. Data normality was assessed using the Shapiro-Wilk test, with non-parametric tests applied as appropriate. Group comparisons utilized Chi-square, one-way ANOVA, Wilcoxon signed-rank, and Kruskal-Wallis tests with Bonferroni post-hoc analysis. A P value ≤ 0.05 was considered statistically significant.

Results: The control group showed no significant difference in the medians of all the profile facial soft tissue measurements and the frontal facial soft tissue measurements, In the facemask and hybrid hyrax group, there was a significant decrease in the following variables after intervention: Naso-labial angle, Mento-labial angle, FH to AB line angle, Upper lip to E-line, Lower lip to A-B line, and Nose tip. There was a significant increase in the medians of the Upper lip to A-B line, and the Horizontal reference line angle. In the facemask and MSE group, there was a significant decrease in the medians of the FH to AB line, Upper lip to E-line, Lower lip to A-B line, Nose tip, Height of lower third, Proportion of lower to upper lip length, Right outer fifth, and Left outer fifth, and a significant increase in the medians of the Naso-facial, and Upper lip to A-B line. The facemask and hyrax group showed the greatest increase in upper lip to E-line, significantly higher than the control group, but not the MSE group. Lower lip to E-line distance decreased in the MSE group and increased in the hyrax group, with significant differences among groups. The MSE group had the largest decrease in lower lip to AB line, followed by the hyrax group, though the difference was not significant. Significant differences were noted among the three groups for the upper lip to AB line distance and nose tip position.

Conclusion: The significant changes observed in various measurements highlight the potential of these treatment protocols to achieve favorable aesthetic and functional outcomes. Both the hybrid hyrax expander-facemask and MSE-facemask protocols are successful in altering the appearance of the facial soft tissues in growing individuals with Class III malocclusion.