Study on the effect of vertical control on the changes in the upper airway size and tongue and hyoid position in adult patients with hyperdivergent skeletal Class II

Abstract

Abstract Background To investigate the effect of vertical control therapy on the size of the upper airway and position of the tongue and hyoid bone in adult patients with hyperdivergent skeletal Class II. Methods Overall, 15 adults with hyperdivergent skeletal Class II and normal occlusion, respectively, were selected as the experimental and control groups. The angle and line of the craniofacial structure, upper airway, and hyoid bone position were measured using the Uceph 4.2.1 standard version software. The three-dimensional (3D) upper airway index was measured using Mimics 21.0. The paired t-test, Wilcoxon symbol rank test of two related samples, t-test of two independent samples, two independent sample nonparametric tests, Mann–Whitney U test, and Pearson correlation analysis were performed, and the statistical significance was considered at P < 0.05. Results After treatment, the S-Go/N-Me (%) and the MP-SN and XiPm-SN angles were significantly different (P༜0.01). The U-MPW and PAS significantly increased (P < 0.05), sagittal diameter L2 increased significantly, and transverse diameter L2 decreased significantly (P < 0.01). Although no significant correlation was observed between the vertical change in the jaw and that in U-MPW and PAS, the sagittal diameter L2 showed a significant correlation (P < 0.05). Furthermore, significant differences between the Hv and sagittal diameter L1 (P < 0.05) were observed before and after treatment. Conclusions After the vertical control therapy in patients with hyperdivergent skeletal Class II, the sagittal size in the two-dimensional region near the mandible increased significantly. However, the 3D indices of the upper airway and the positions of the tongue and hyoid bone did not change significantly, but the upper airway only underwent adaptive changes during treatment. Furthermore, compared with normal occlusion, the velopharyngeal segment airway of patients with hyperdivergent skeletal Class II remains narrow and long after treatment.