不同骨型人群髁突不对称性的锥形束CT评价

Evaluation of condylar asymmetry in different skeletal patterns with cone-beam CT

目的:利用锥形束CT(cone-beam CT,CBCT)评价不同骨型人群中的髁突不对称性.方法:收集拍摄CBCT的个体共110名,年龄18~30岁.对CBCT数据进行三维重建、建立参考系并三维定点.所有个体按照不同骨型进行分组,组Ⅰ(Cl Ⅰ)为骨性Ⅰ类(0°≤ANB≤5°),组Ⅱ(Cl Ⅱ)为骨性Ⅱ类(ANB>5°),组Ⅲ(Cl Ⅲ)为骨性Ⅲ类(ANB<0°),每组按性别进一步分组.输出定点坐标,计算髁突(Co-Sig)的不对称情况,同时分析下颌支(Go-Sig)以及髁突-下颌支(Co-Go)的对称性.采用SPSS 17.0软件包对数据进行统计学分析.结果:组Ⅱ和组Ⅲ间的髁突-下颌支不对称性(Co-GoR-L)具有统计学差异(P<0.05),差异在三维上主要体现在y坐标(P<0.05);组Ⅰ和组Ⅲ以及组Ⅱ和组Ⅲ间的下颌支不对称性(Go-Sig R-L)也受不同骨型影响,具有统计学差异(P<0.05),差异在三维上同样体现在y坐标(P<0.05).左右侧髁突、下颌支以及髁突-下颌支在部分人群中体现出性别差异及偏侧性差异(P<0.05),且这种偏侧性均表现为右侧优势.颏下点(Me)的z坐标在不同骨型人群中的差异较大(P<0.05),而x和y坐标无统计学差异(P>0.05).结论:髁突-下颌支以及下颌支的不对称性与不同人群的骨型相关,差异主要来源于高度.骨性Ⅲ类和Ⅱ类人群分别表现为下颌骨前突和下颌骨后缩.颏部偏斜与髁突不对称性的关系需要进一步探讨.

PURPOSE: The aim of this study was to evaluate condylar asymmetry in different skeletal patterns with conebeam CT (CBCT). METHODS: A total of 110 subjects aged from 18 to 30 years were selected from patients who had undergone CBCT examinations retrospectively. All the subjects were divided into three groups according to their skeletal patterns: Class Ⅰ(Cl Ⅰ: 0°WANBW5.),Class Ⅱ(Cl Ⅱ: ANB>5°) and Class Ⅲ(Cl Ⅲ: ANB<0°). In addition, each group was further divided into two subgroups according to genders. Condylar (Co-Sig), ramus (Go-Sig) and condyle-plusramus (Co-Go) asymmetry were assessed by identifying landmarks on the reconstructed images with a 3-dimentional (3D) reference plane. The coordinates of the landmarks were calculated statistically. The data were analyzed statistically with SPSS 17.0 software package. RESULTS: The condyle-plus-ramus and ramus asymmetry (Co-Go R-L and Go-Sig R-L) were affected by the ANB angle (P<0.05) respectively, and the differences mainly came from the y coordinate (P<0.05). When comparing the two sides of the three groups respectively, the Co-Go, Go-Sig and Co -Sig of some patients had gender difference and left-right difference. The z coordinate of point Menton (Me) had significant difference (P<0.05) caused by different skeletal patterns, while the coordinates of x and y were similar (P>0.05). CONCLUSIONS: Condyleplus- ramus and the ramus asymmetry were affected by different skeletal patterns and the differences were caused by the height primarily. Patients of Class Ⅲ usually manifest mandibular protrusion while Class Ⅱ with mandibular retrognathism. Whether the degree of chin deviation differs according to the condylar asymmetry needs further investigation.