The Study Of Vertical Control On The Changes In The Upper Airway Size And Tongue And Hyoid Position In Adult Patients With Hyperdivergent Skeletal Class Ⅱ

Objective:To analyze the changes of upper airway size,tongue body,and hyoid position in adult patients with hyperdivergent skeletal ClassⅡafter vertical control therapy using CBCT,and to provide reference for orthodontic design and efficacy evaluation.Materials and Methods:From January 2019 to January 2022,15 patients with Class II high angle who were admitted to the Orthodontics Department of Lanzhou University Stomatological Hospital（and met the inclusion criteria）were selected for lateral cephalometric and CBCT imaging before and after treatment.In the treatment group,7 males and 8females（average age:25.40±3.28 years）were included.Selecting 15 individual normal occlusion patients as the control group,including 7 males and 8 females（average age 25.32±1.65 years）and collecting lateral cephalometric films and CBCT results.Measuring craniomaxillofacial structural angle,line distance,sagittal size of upper airway,and hyoid position using lateral cephalometric radiographs.Importing the CBCT results in DICOM format into the Mimics 21.0 software,and measured the total volume of the upper airway,the volume of each segment,the height of the palatopharyngeal segment and glossopharyngeal segment,the minimum cross-sectional area S₁of the palatopharyngeal segment,the minimum cross-sectional area S₂of the glossopharyngeal segment,the minimum cross-sectional sagittal diameter L₁and transverse L₁of the palatopharyngeal segment,the minimum cross-sectional sagittal diameter L₂and transverse L₂of the glossopharyngeal segment,and the size of the space between the tongue body and the top of the palate.Results:1.The difference between the control group and the treatment group before treatment showed that there were no significant difference in the volume,total volume,height of the glossopharyngeal segment,minimum cross-sectional area S₁of the palatopharyngeal segment,minimum cross-sectional area S₂of the glossopharyngeal segment,transverse diameter L₁,sagittal diameter L₂,and transverse diameter L₂,IAV of the upper airway（P>0.05）.There were significant differences in the height and sagittal diameter L₁of the palatopharyngeal segment between the two groups（P<0.05）.2.The analysis of craniomaxillofacial structure in the treatment group showed that the ANB angle significantly decreased after treatment（P<0.01）,the MP-SN decreased,the S-Go/N-Me（%）increased,and the true mandibular reverse rotation angle（Xipm-SN）decreased after treatment.There were significant differences in the results of MP-SN,S-Go/N-Me（%）,and Xipm-SN before and after treatment（P<0.01）.The results of U₁-SN before and after treatment showed significant changes（P<0.01）.The measured value of Overjet of anterior teeth decreased significantly after treatment（P<0.01）.3.After treatment,the sagittal size of the upper airway showed a significant increase in U-MPW and PAS（P<0.05）.4.The hyoid position results showed that there was no significant change in its position after treatment（P>0.05）.5.The three-dimensional airway results showed that there were no significant changes in the total volume of the upper airway,the volume of each part,the height of the palatopharynx,the height of the glossopharynx,the minimum cross-sectional area S₁,the minimum cross-sectional area S₂,the minimum cross-sectional sagittal diameter L₁,the minimum cross-sectional transverse diameter L₁,and the IAV of the glossopharynx after treatment（P>0.05）,while there were significant changes in the minimum cross-sectional sagittal diameter L₂,and the minimum cross-sectional transverse diameter L₂of the glossopharynx（P<0.01）,the sagittal diameter L₂increased significantly,while the transverse diameter L₂decreased significantly after treatment.6.Pearson correlation test showed that there was no correlation between ANB,MP-SN,S-Go/N-Me（%）,Xipm-SN,and upper airway sagittal dimensions U-MPW,PAS（P>0.05）.7.There was no correlation between the ANB angle and the minimum cross-sectional sagittal diameter L₂and the transverse diameter L₂of the glossopharyngeal segment（P>0.05）,but there was a significant correlation between the MP-SN,S-Go/N-Me（%）and the minimum cross-sectional sagittal diameter L₂of the glossopharyngeal segment（P<0.05）.8.There was no significant correlation between U-MPW,PAS,sagittal diameter L₂,transverse diameter L₂changes and U₁-SN,Overjet（P>0.05）.9.Univariate linear regression analysis showed that the variables ANB angle and ANS-Me/N-Me（%）were negatively correlated with the variables S₁and PNS-UPW,respectively（P<0.05）.The variable U₁-SN had a negative correlation with the variable IAV（P<0.05）,and a positive correlation with the sagittal diameter L₂（P<0.05）.The variable Overjet had a negative correlation with the transverse diameter L₁,while it had a positive correlation with the variable S₂（P<0.05）.The variable Overbite was positively correlated with PNS-UPW and U-MPW（P<0.05）.The variable MP-SN had a negative correlation with the sagittal diameter L₂（P<0.01）,PNS-UPW（P<0.05）,and H-MP（P<0.05）variables,while the variable S-Go/N-Me（%）had a positive correlation with the above variables.Multiple linear regression analysis showed that the variable MP-SN had a significant negative correlation with sagittal diameter L₂,while the variable S-Go/N-Me（%）had a significant positive correlation with H-MP（P<0.05）.10.After treatment,there was no significant difference in the volume,total volume,height of the glossopharyngeal segment,minimum cross-sectional area S₁,transverse diameter L₁,sagittal diameter L₂,transverse diameter L₂,and IAV between the treatment and the control group（P>0.05）.There were significant differences in the height,sagittal diameter L₁of the palatopharyngeal segment,and minimum cross-sectional area S₂compared with the control group（P<0.05）.Conclusion:1.Before treatment,the velopharyngeal airway in adult patients with skeletal class II high angle was narrow and long,and although vertically controlled by orthodontics,the velopharyngeal airway remained unchanged.2.Orthodontic vertical control treatment significantly increased the two-dimensional airway size near the angle of mandible.3.Orthodontic vertical control significantly increased the sagittal diameter of the glossopharyngeal segment,but at the same time caused a significant decrease in the transverse diameter,without causing a change in the minimum cross-sectional area of the glossopharyngeal segment.4.Orthodontic vertical control did not affect the position of the tongue and hyoid.