A Comparative Study Of The Median Sagittal Plane Determined By Soft Tissue Marker And Three-point Method In Patients With Craniofacial Asymmetry

Objective: To evaluate the reliability and accuracy of the midsagittal plane determined by the three-bone tissue point and the midsagittal plane determined by soft tissue points,and to provide a better reference plane for the study of three-dimensional structural symmetry of patients with craniofacial asymmetry,and to provide a theoretical basis for clinicians’ diagnosis and surgical design.Methods: A retrospective analysis was performed on 40 patients with dentofacial deformitiy in the Oral and Maxillofacial Surgery,China Medical University School &Hospital of Stomatology from September 2018 to August 2020.The subjects were divided into two groups: the first group was patients with craniofacial asymmetry,and the second group was patients with craniofacial symmetry,20 people in each group.3D CT of craniofacial bone was taken preoperative,and data were reconstructed into digital model of bone and soft tissue using Proplan CMF 3.0 software.Ten marker points were marked and construct the median sagittal plane of bone tissue and the median sagittal plane of soft tissue.The average distance from each group to the two median sagittal planes was calculated.SPSS 26.0 software was used for statistical analysis.Results: There was no significant difference in gender and age between two groups(P<0.05).The difference between each landmark point to the median sagittal plane of soft tissue and the median sagittal plane of bone tissue was statistically significant(P<0.05).The mean and standard deviation of the distance from each landmark point to soft tissue mark point were all less than the mean and standard deviation of the distance from the bone three-point method.The mean and standard deviation of the distances between the measurement marks in the upper,middle and lower parts and the two central sagittal planes were gradually increased from the upper part to the lower part.Conclusion: Compared with the bone three-point method,the median sagittal plane determined by soft tissue landmark was more close to the true symmetric plane and had better stability.The central sagittal plane determined by the three-point method of bone tissue may exaggerate the degree of asymmetry in patients,resulting in surgical design errors.Cranial and facial asymmetry deformity is mainly caused by the mandible,and the degree of deformity is gradually increasing from top to bottom.