A Cone-beam CT Analysis Of The Changes Of The Condylar Position In Skeletal Class ? Patients With Mandibular Deviation Before And After BSSRO Surgery

Objective: Applying the measurement of Cone Beam Computed Tomography(CBCT)to evaluate and analyze the changes of the condylar position in three dimensional directionsin of the skeletal Class III patients with mandibular deviation before and after Bilateral Sagittal Split Ramus Osteotomy(BSSRO)surgery,as well as the causes of these changes.This investigation could be also used to explore influences of the BSSRO on condylar position,in order to provide the basis for the clinical diagnosis and treatment of these patients.Methods: Select 25 cases of skeletal Class III patients with mandibular deviation,within 1 week before the BSSRO operation(T1),within 1 week after operation(T2),during 6 ~ 8 months after operation(T3).These three different periods are scanned by the Cone Beam Computed Tomography.After the DICOM data collection,the software of Mimics17.0 will be used to reconstruct the 3D images.The anatomical structures of the craniofacial and condylar processes of the above periods were marked and measured with the related measurement items of the condyle-craniofacial structure,to analyze the changes of measurement items in different periods.Making comparisons of the differences between the condylar position and the changes of the condylar position before and after operations.SPSS19.0 software was used to analyze the data,and the test level was set as ?=0.05.Results: 1.Within 1 weeks before operation,the distance between the shifted side of the condylar apex and Standard Horizontal Plane(SHP),the angle of the Condyle Sagittal Plane(CSP)and Middle Sagittal Plane(MSP),and the posterior joint space were obviously increased.The distance between the condylar apex and the(Sella Coronal Plane)SCP,the angle of the Condyle Coronal Plane(CCP)and the MSP were decreased significantly(P<0.05),and the non-shifted side of the condylar apex to MSP distance.The angle of the CCP and the MSP angle,the anterior joint space and the medial joint space were obviously increased,and the angle of the CCP and the SCP were decreased significantly(P<0.05).2.During 6-8 months after operation,there was no significant difference in other measurement indexes(P>0.05)except the distance between the shifted side condylar apex and the SHP,the posterior joint space and the distance between the non-shifted side condylar apex and the SCP were increased(P<0.05).Conclusion:1.Within 1week after the operation of BSSRO,the shifted side condyle was moved forward,downward and inward rotation.Meanwhile,the non-shifted side condyle was moved backward,outward and outward rotation.2.The position of bilateral condyle will be changed after 6-8 months to some extents,but the trend was gradually restored to the condyle position before operation.