| Objective:In this study,CBCT was used to analyze the differences between adult skeletal class II high angle and individual normal temporomandibular joint bony structures,and at the same time,the changes of condyle shape,position,articular fossa morphology in adult skeletal class II high angle patients after the treatment of mandibular counterclockwise rotation were compared,and whether there is a correlation between the change in the counterclockwise rotation of the mandible and the change in the joint position,which provide a reference for orthodontic clinical diagnosis and treatment plan design.Methods: From October,2017 to November,2020,among the patients who were treated in the Orthodontics Department of Stomatological Hospital of Lanzhou University and took CBCT before and after orthodontic treatment,20 cases of adult skeletal class II high angle patients who took the initiative in vertical control were selected as the experimental group,and 20 normal adults who volunteered to take CBCT as control group.The CBCT file was imported into the Invivo 5 software in the form of DICOM for 3D reconstruction and correction,and the vertical indicators（mandibular plane angle,posterior-anterior height ratio,mandibular true rotation angle）in the lateral cephalogram were measured,and the condyle shape in the TMJ structure（condylar mediolateral diameter,anteroposterior diameter,condyle maximum axial area,condylar head height,condylar height,anterior and posterior slope length,angle between anterior and posterior slope of condyle）,position of condyle（anterior,super and retro articular space,inter,middle,and extra condylar space）,and the shape of the articular fossa（articular fossa width,articular fossa depth,articular nodular angle）,a total of 20 measurement items.The above data were processed by SPSS 22 software.Use Shapiro-Wilk to test whether the data obeyed the normal distribution,and t test was performed on the normally distributed variables,and the mean（）and standard deviation（SD）represent measurement data.Wilcoxon signed-rank test is performed for non-normally distributed variables,and 25%,median and 75% of measurement values are used to represent measurement data.Before and after treatment,the data on bilateral of the experimental group and the control group were respectively subjected to paired t-test,the experimental group and the control group were subjected to independent sample t-test before treatment,and the paired t-test was performed before and after treatment in the experimental group,and the Pearson correlation coefficient was calculated to determine correlation between changes in mandibular counterclockwise rotation（ΔMP-SN,ΔS-Go/N-Me%and ΔXi Pm-SN）and changes in joint space（ΔAS,ΔRS,ΔSS,ΔIS,ΔES,ΔMS）.The significant level P < 0.05,which means it is statistically significant.Results: 1.Paired t-test was performed on the left and right temporomandibular joints of skeletal class II high angle before and after treatment in adult patients,and the measurement items of individual normal and left and right temporomandibular joints were respectively tested,and there is no significant difference in the measurement results between the two sides（P> 0.05）,the joints on both sides of two groups are basically symmetrical.2.An independent sample t-test of temporomandibular joint measurements in adult patients with skeletal class II high angle compared with individual normal combinations revealed that with skeletal class II high angle in adult patients had smaller condylar mediolateral diameter,anteroposterior diameter,condyle maximum cross-sectional area,condylar posterior slope length,condylar superarticular space,retroarticular space,condylar middlecondylar space,extracondylar space,condylar height,condylar head height,and articular fossa depth compared with individual normal combinations,which were statistically significant（P < 0.05）;3.Skeletal class II high angle after treatment with mandibular counterclockwise rotation,mandibular plane angle and mandibular true rotation angle decreased after treatment compared with pretreatment,and posterior anterior height ratio increased compared with pre-treatment,（P < 0.05）;4.Paired t-test of condylar morphology in adult skeletal class II high angle patients before and after treatment by mandibular counterclockwise rotation revealed that condylar mediolateral diameter,anteroposterior diameter,condyle maximum cross-sectional area and condylar head height increased after treatment（P < 0.05）;5.Individual cases of anterior displacement,neutral position and posterior displacement were 3 cases（35%）,10 cases（50%）and 7 cases（15%）respectively;the experimental group before treatment was 30%,40%,and 30%,respectively,The anterior displacement,neutral position and posterior displacement of adult skeletal class II high angle treatment were 6 cases（30%）,10 cases（40%）and 4 cases（30%）respectively.In the neutral position,the condylar space index of 6 patients was closer to the neutral position,and the distribution of the condyle space was better and uniform.;6.A paired t-test of condylar position before and after treatment of adult skeletal class II high angle patients by mandibular counterclockwise rotation revealed that intercondylar space and extracondylar space were reduced after treatment compared（P< 0.05）;Anterior condylar displacement had a decrease in the superarticular space and retroarticular space,intercondylar space,middlecondylar space and extracondylar space,and an increase in the anterior articular space after treatment;patients with neutral anterior condylar displacement had no significant change in the joint space in sagittal and coronal positions after treatment;patients with posterior condylar displacement had a decrease in the anterior articular space and superarticular space,intercondylar space,middlecondylar space and extracondylar space,and an increase in the retroarticular space after treatment;7.Paired t-test of articular fossa morphology in adult skeletal class II high angle patients before and after treatment by mandibular counterclockwise rotation revealed that articular fossa width,articular fossa depth and articular nodular angle increased compared with those before treatment,with statistical significance.（P < 0.05）;8.After correlating the amount of change in counterclockwise rotation of the mandible with the amount of change in joint space after treatment of bony class II high angle in adults,it was found that a negative correlation between the amount of change in the coronal intercondylar,middlecondylar and extracondylar space and the amount of change in the anterior posterior height ratio in the amount of mandibular counterclockwise rotation,and the highest degree of correlation exists for the intracondylar space（P < 0.05）.Conclusion: 1.The shape and position of the left and right temporomandibular joints before and after treatment of adult skeletal class II high angle,and individual normal and left and right temporomandibular joints are not obvious,basically symmetrical.2.Adult bony class II high angle have smaller condylar morphology than individual normal fits,short and thin condyles,low and flat articular fossa,and the condyles are anteriorly displaced,neutrally displaced and posteriorly displaced in the sagittal position,and laterally displaced in the coronal position.3.After treatment of adult skeletal class II high angle patients,the vertical direction of the mandible is controlled,the mandible rotates counterclockwise,the upper and lower teeth are aligned,the overbite of the anterior teeth is normal,the profile is improved,and the condyle and joint socket grow and remodel.4.After correlating the amount of change in counterclockwise rotation of the mandible and the change in joint position in adult patients with bony class II high angle,it revealed that there was a significant negative correlation between the amount of change in the posterior anterior height ratio of the vertical upward measurement index before and after treatment and the amount of change of coronal intercondylar,middlecondylar and extracondylar space,and the highest correlation was found for the intercondylar space. |
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