目的　通过螺旋CT及曲面断层片探讨下颌神经管与下颌骨的实际位置关系。  方法　利用螺旋CT扫描机对正常年青人进行下颌骨的横断面连续薄层扫描及多平面重建后，测量并计算下颌神经管在下颌骨中的实际位置及其走行方向。对上述人群拍摄曲面断层片，在曲面断层片上测量并计算下颌神经管在下颌骨中的位置并将两种测量结果进行比较。  结果　在颊舌方向,下颌神经管总体走行是由舌侧逐渐向颊侧倾斜达颏孔，在走行高度上，在第三磨牙区由上向下走行，自第二磨牙开始下颌神经管逐渐由下向上走行达颏孔。下颌神经管在下颌骨中位置的测量并计算的比值，在两种检测方法中无显著性差异（P＜0.05）。  结论　本研究螺旋CT测量并计算出的比值校正曲面断层片测量并计算的结果，可以在临床工作中指导牙槽外科手术。

Objective　To investigate anatomic features of the mandibular canal under spiral CT and panoramic radiography.　Methods　Mandibles of healthy young volunteers were continuously scanned transversally by spiral CT, and by panoramic radiography, respectively, followed by 3D reconstruction. The anatomic position of mandibular canal was measured and compared according to two kind of reconstructed images.　Results　At the buccal-lingual direction, mandibular canal inclinated gradually from lingual surface to buccal surface and reached mental foramen finally, which coursed through the third and second molars before reaching mental foramen. There were no anatomic difference could be identified between two kinds of skills（P＞0.05）.　Conclusions　Spiral CT scan supplied with panoramic radiography detection is reliable for guiding the alveolar operation.