曲面断层摄影变形失真的初步研究

A preliminary study on distortion of the orthopantomograph

目的 探讨曲面断层摄影不同部位的变形失真率。方法 选择１５个不同大小的干性下颌骨标本，分为少年组，青壮年组和老年组三组，分别在基准位置下重复摄片。利用直径为２ｍｍ±０．０１ｍｍ的钢珠在标本不同部位定位．测量，并进行统计分析；结果 不同组标本，不同部位的钢珠径长存在显著差异（Ｐ＜０．０１）。在基准位置下，颏孔及下颌孔部的变形失真率最大。结论 曲面断层摄影各部位变形失真率不同，这为指导临床工作，如颌骨畸形矫正术中截骨线位置的确定。种植体的定位、阻滞麻醉等，提供了量化的依据。

Objective To find out the distortion of the orthopantomograph at the different parts of the mandibles. Methods Fifteen dried mandibles were selected and divided into three groups (the children, the young adult and the old). At different parts of the mandibles. stainless steel balls measuring about 2 mm± 0.01 mm in diameter were embedded for the measurement markers. Orthopantomograph were taken at a standard position. Results Statistical analysis showed that then were significant difference among different groups, different parts of the mandible( P < 0.01). The largest distortion was at mental and mandible foramen regions at standard positon. Conclusion Distortion at the different parts of the orthopantomograph is different, therefore, the result should be beneficial for the clinicians in determination of bone cut of orthognathic surgery. localization of implant. block anaesthesia and so on.