Study On The Morphology Of Upper Airway Before And After Bilateral Sagittal Split Ramus Osteotomy In Patients With Skeletal Maxillary

Objective:Based on the MIMICS 3D reconstruction technique and three-dimensional registration technique of CBCT data,before and after the bilateral mandibular ramus osteotomy,the three-dimensional morphological evaluation of the upper airway of the patients was performed which provide surgical plan and the evaluation of therapeutic effect some reference.Materials and Methods:In this study,5 patients(2 males and 3 females)were enrolled in this study.The age of the patients was 2.20 ± 1.87 years old.The patients were divided into two groups,CBCT scan was performed 1 week before and 6 months after the bilateral mandibular ramus osteotomy,and CBCT scan data was imported into MIMICS17.0 software for 3D reconstruction and 3D registration of the same patient's preoperative and postoperative data.The three-dimensional morphological parameters of the upper airway before and after treatment were analyzed by t test or rank sum test.For the mandibular horizontal position and the upper airway morphological parameters(hyoid horizontal displacement H-C3,upper airway volume V,velopharyngeal volume V2,tongue pharyngeal volume V3,throat volume V4,airway mean cross-sectional area Smean,airway minimum cross-sectional area Smin,minimum cross-sectional area front and rear diameters ratio Da / Dl)correlation relationships were analyzed using Pearson correlation analysis.Results:After orthodontic surgery,the position of the hyoid bone was moved rearward,the upper airway velopharyngeal volume,the velopharyngeal volume,the glossopharyngeal volume,the hypopharyngeal volume,the average cross-sectional area,the upper airway average cross-sectional area,the minimum cross-sectional area,the minimum cross-sectional area and the ratio of left and right diameter of the anteroposterior diameter were significantly reduced.Conclusions:In patients with the bilateral mandibular ramus osteotomy,The hyoid move backward significantly and the volume of the upper airway,the volume of the 4 parts of upper airway were reduced,the changes of the velopharynx ? glossopharyngeal and hypopharyngeal are Significantly,the average cross-sectional area of the upper airway and the minimum cross-sectional area are significantly reduced,and the minimum cross-sectional area is inclined to oval.because of the complex relationship between the position of the maxilla and the air flow in the upper airway,the amount of setback>8mm is not a contraindication.