Skeletal Class Ⅲ Adults With Different Vertical Skeletal Facial Types:Analysis Of The Morphologies And Positions Of Tongue And Mandible

Purpose:To investigate the morphological characteristics and positions of the tongue and morphological characteristics of the mandible in skeletal class Ⅲ adult patients with different vertical facial types.To provide reference for clinical diagnosis and curative effect prediction for skeletal class Ⅲ patients with different vertical skeletal facial types.Materials and Methods: Fifty-five adult patients with complete clinical records and consistent CBCT imaging data collection methods who visited the Orthodontic Department of Dalian Stomatological Hospital Affiliated to Dalian Medical University from September 2018 to October 2020 were selected as the research objects,and they were divided into three groups according to different vertical facial types:low angle group(15 cases,including 7 males and 8 females,with an average age of 22.73 ± 3.69),average angle group(20 cases,including 9 males and 11 females,with an average age of 23.06 ± 3.64)and high angle group(20 cases,including 9 males and 11 females,with an average age of 21.10 ± 2.95).All subjects were scanned by cone beam computed tomography(CBCT),the collected DICOM data were processed by mimics19.0 software for three-dimensional modeling.The shape of mandible,the length and height of tongue,the vertical and horizontal positions of tongue were measured.SPSS25.0 software was used for statistical analysis.Normal distribution and homogeneity of variance were tested for the data of the three groups of low angle group,average angle group and high angle group.One-way analysis of variance analysis was performed when the data were in line with normal distribution and homogeneity of variance,and non-parametric test was performed when the data were not in line with normal distribution and homogeneity of variance.when p < 0.05,there was statistical difference.Results:(1)The length of mandible body(Go-Me)and the angle of mandible angle(∠Co-Go-Me)in high angle group were larger than those in average angle group and low angle group,but there was no significant difference between average angle group and low angle group;(2)The width of upper end(Co-Co’),width of lower end(Go-Go’),and vertical opening of mandible(∠Co-Me-Co’)in the low angle group were greater than those in the high angle group;the width of upper end(Co-Co’)and vertical opening of mandible(∠Co-Me-Co’)in the low angle group were greater than those in the average angle group,but there was no significant difference between average angle group and high angle group;(3)Tongue’s morphology:The length and height of the tongue in the low angle group were larger than those in the high angle group,but there was no significant difference between average angle group and high angle group;(4)Tongue’s positions:The distance(S-S’)of the tongue in the low angle group was smaller than that in the high angle group,and the distance(S’-T)was larger than that in the high angle group,but there was no significant difference between average angle group and high angle group.(5)Hyoid bone’s positions:The distance(H-S(X))of hyoid bone in low angle group was smaller than that in high angle group,while the distance(H-BA(Y))of hyoid bone in low angle group was larger than that in high angle group,but there was no significant difference between average angle group and high angle group.Conclusion:(1)The length of the mandibular body and the angle of the mandibular angle of adult patients with skeletal class Ⅲ high angle are larger than those of the average and low angle patients.(2)The width of the upper and lower ends and vertical opening of the mandible in skeletal class Ⅲ low angle adult patients are larger than those in high angle patients.The width of the upper ends and vertical opening of mandible are larger than those in average angle patients.In low-angle patients,the back of the mandible is wider.(3)The length and height of tongue in skeletal Class Ⅲ low angle adults were larger than those in high angle group.(4)The position of the tongue and hyoid bone in skeletal class Ⅲ adult patients is lower and more posterior compared to low-angle patients.