CBCT Analysis Of Condyle Features And Inclination Of The Occlusal Plane In Skeletal Class Ⅲ Malocclusion Patients With Mandibular Asymmetry

Objective:CBCT was adopted to measure and analyze condyle features and inclination of the occlusal plane of skeletal class III patients between with and without mandibular deviation,and to explore the interaction between mandibular deviation and the characteristics of the condyle and occlusal plane,to provide reference for the orthodontic treatment of skeletal ClassⅢmalocclusion patients with mandibular asymmetry.Methods:Selected adult patients with skeletal class III who meet the inclusion criteria and took CBCT.According to the distance from the submental point to the midsagittal plane,all the subjects were divided into skeletal class III with mandibular deviation and skeletal class III without mandibular deviation group.Dolphin was used to measure the distance of mandibular deviation,left and right inclination of the occlusal plane,condylar position and morphology in each group.In the case of data conforming to a normal distribution,paired samples t-test was used to compare differences between two groups;Pearson correlation analysis was used to evaluate the correlation between mandibular deviation and occlusal plane and condyle position;by the use ofχ~2test and Fisher’s test,the sagittal position of the condyle in the joint fossa of the two groups of patients was statistically analyzed.Results:1.There were statistically significant differences in the angle between OP and FH plane,the anterior joint space,superior joint space,lateral joint space and condylar mediolateral diameter between the deviated sides and opposite side in skeletal ClassⅢmalocclusion patients with mandibular asymmetry(P<0.05).Compared with the opposite side,which showed a smaller angle between OP and FH plane,a smaller mediolateral diameter of the condyle,larger anterior,superior,and lateral joint spaces,and a higher proportion of joint posteriority in deviated side.2.There were no statistically significant differences between the left and right inclination of the occlusal plane,condylar position,and morphology in skeletal class III patients without mandibular deviation(P>0.05),and the joint was predominantly in anterior and middle position.3.Mandibular deviations were positively correlated with both the anterior joint space of the deviated side and the angle between OP and FH plane of the opposite side(P<0.01).Conclusion:1.Patients with skeletal class III malocclusion have smaller occlusal plane angles and the mediolateral diameter of the condyle.And the displacement of the lateral condyle to the posterior,lower,and inner sides suggests that clinical doctors should closely monitor the temporomandibular joint of patients with mandibular deviation before orthodontic treatment begins,to prevent the occurrence or aggravation of symptoms of temporomandibular joint disorder during treatment.2.Through correlation analysis,this study found that there was a positive correlation between the degree of mandibular deviation and the anterior joint space of the deviated side and the angle between OP and FH plane of the opposite side.This suggests that in clinical practice,for patients with mild skeletal class III malocclusion,the correct mandibular position can be determined through occlusal plates and orthodontic treatment,removing occlusal interference,correcting the inclination of the occlusal plane,coordinating the shape of the dental arch,and solving problems such as mandibular asymmetry.