CBCT Research On TMJ Morphological Changes Before And After Orthodontic Treatment Of Skeletal Class Ⅱ Deep-Overbite Adult Patients

Objective: Through the comparative analysis on individual normal occlusion and skeletal class Ⅱ deep-overbite occlusion via cone beam CT(CBCT),this study researches into the difference of the internal structure and the location of the joints with individual normal occlusion and skeletal class Ⅱ deep-overbite occlusion and at the same time uses the cone beam CT(CBCT)to observe the condylar morphology,articular fossa morphology as well as the change of position of condyle in articular foss of patients with skeletal class Ⅱ deep-overbite occlusion without TMJ symptoms before and after orthodontic treatment analyze the influence of orthodontic treatment on the TMJ morphology of patients with skeletal class Ⅱ deep-overbite occlusion,so as to provide some reference for clinical orthodontist’s diagnosis,treatment design and evaluation of correction effects.Methods: Malocclusion patients admitted to the Orthodontic Department of Stomatology Hospital of Shenyang from August 2016 to August 2018 were selected as the research objects.Select 20 patients with adult skeletal class Ⅱ deep-overbite occlusion as an experimental group,and take CBCT for the patients were before and after therapy;select 20 people with adult individual normal occlusion as the control group,and take CBCT.Import the data of CBCT file into Invivo Dental 5 software,use Invivo Dental software 5 to perform 3D reconstruction for patients with craniofacial region,cut out condylar and articular fossa site,measure the required items,input themeasured results to Microsoft Excel software for organization,import the organzied data to SPSS 22.0 software,compare the experimental group before and after the treatment,and compare it with the control group respectively.The changes of patients before and after treatment will be analyzed by paired t test,and the comparison between and normal occlusion will be analyzed by independent sample t test.When the test standard is P < 0.05,it is statistically significant.Result:1.The morphological comparison of TMJ on the right and left sides of individual normal occlusion in adults showed that the morphological measurement values of TMJ on the right and left sides of individual normal occlusion in adults had no statistical difference(P > 0.05),which was basically symmetrical.2.The morphological comparison of TMJ on the right and left sides of patients with skeletal class Ⅱ deep-overbite occlusion showed that the the morphological measurement values of TMJ on the right and left sides of patients with skeletal class Ⅱdeep-overbite occlusion had no statistical difference(P > 0.05),which was basically symmetrical.The morphological comparison of TMJ on the right and left sides of patients with skeletal class Ⅱdeep-overbite occlusion after treatment showed that the the morphological measurement values of TMJ on the right and left sides of patients with skeletal class Ⅱ deep-overbite occlusion after treatment had no statistical difference(P > 0.05),which was basically symmetrical.3.The morphological comparison of TMJ of patients with skeletal class Ⅱdeep-overbite occlusion and adult with individual normal occlusion showed that the patients with skeletal class Ⅱ deep-overbite occlusion is smaller than the adult with normal occlusion in condylar maximum area,condylar perpendicular height,outer joint space,superior joint space,posterior joint space,condylar pass angle,articular eminence to the FH plane angle and height of the fossa,the difference was statistically significant(P < 0.05);and that the patients with skeletal class Ⅱ deep-overbite occlusion is larger than the adult with normal occlusion in length of interior point,radius,which was statistically significant(P < 0.05).4.The morphological comparison of TMJ of patients with skeletal class Ⅱdeep-overbite occlusion before and after treatment showed that,in terms of condylar morphology,the condylar maximum area,condylar anteroposterior diameter,condylar medialateral diameter after treatment were smaller than those before,the anterior slope,condylar apex height increases,and the differences were statistically significant(P <0.05);In terms of articular fossa morphology,the condylar pass angle,articular eminence to the FH plane angle,total height of the fossa,upper height of the articular fossa and lower height of the articular fossa increased significantly,and the front –rear width of the articular fossa decreased significantly after the correction,with statistically significant differences(P < 0.05);at the position of the condyle,the anterior joint space of the condyle was significantly reduced after correction,and the medial joint space,posterior joint space and superior joint space of the condyle were increased,with statistically significant differences(P < 0.05).Conclusion: 1.The morphology of bilateral temporomandibular joint(TMJ)in some normal occlusal population has little difference and is basically symmetrical.2.The morphology of TMJ on the right and left sides of patients with skeletal class Ⅱdeep-overbite occlusion before and after treatment is basically symmetrical.3.Compared with normal occlusal population,the patients with skeletal class Ⅱdeep-overbite occlusion had smaller condylar maximum area,condylar perpendicular height and height of the fossa,and smooth articular fossa,and the condyle is in the outer posterior position in fossa.4.After orthodontic treatment,the patients with skeletal class Ⅱ deep-overbite occlusion had their condylar maximum area,condylar anteroposterior diameter,condylar medialateral diameter,length of anterior slope and condylar apex height increased,condylar pass angle,articular eminence to the FH plane angle increased,the width of the articular fossa decreased,the condylar position in the fossa is changed from relatively outer posterior into relatively center.