头颅后前位X线头影测量正中矢状参考线的选择研究

A posteroanterior cephalometric selection of the mid-sagittal line in adults normal occlusion

目的:对成人正常牙合后前位X线片中常用的4条正中矢状参考线进行比较,以评价其可靠性和准确性。方法:在同一供测人群中,挑选80例山东地区成人正常牙合,由同一操作者按照统一的标准严格定位、拍摄头颅后前位X线片,计算8对解剖标志点相对4条常用正中矢状参考线的Dtotal。结果:在眼、鼻、口区域,各标志点相对参考线A的Dtotal为最小。且8对解剖标志点相对参考线A的4项(T1M1、T1M2、T2M1、T2M2)平均Dtotal间差异无统计学意义。结论:两侧眶外侧点连线的垂直平分线是应用后前位X线片时可靠的正中矢状参考线。

Objective: To evaluate four mid-sagittal lines' reproducibility and accurateness and obtain the most reliable one through studying posteroanterior cephalometrics of adults normal occlusion. Methods: Eighty subjects were selected, each one was positioned in the same cephalostat in natural head position. The Dtotal of the bilateral landmarks related to the four different midlines was calculated by the same operator. The best mid-sagittal line would be the line with the lowest Dtotal. Results: Plane A generally showed the lowest Dtotal for the landmarks in the regions related to the eyes,nose and mouth. No main or interaction effects for repeated measurements and recordings were determined. Conclusion: The best mid-sagittal line in posteroanterior cephalometrics is the line perpendicular to and bisecting the line that connecting landmarks exocanthion.