目的　为下颌牙种植术等临床口腔外科提供解剖学基础。  方法　选取全牙志愿者20名，在螺旋CT机以眶耳线(OML)为基线连续扫描，采用ADW 4.2重建软件的曲面重组技术(CPR)重建下颌管，观察下颌管的位置、构造和测量下颌后牙牙根至下颌管上壁的距离；在Amira三维重建软件下重建下颌骨及下颌管的可视化模型，观察透明下颌骨内下颌管的走行及其与下颌后牙的关系。  结果　下颌管壁由一薄层骨密质构成，自磨牙牙根尖舌侧和前磨牙牙根尖颊侧的下方走行；透明下颌骨内的下颌管可清晰显示其位置、形态及走行，下颌管与下颌体下缘、牙槽嵴及内、外侧骨板的距离。下颌后牙牙根至下颌管的距离以第2磨牙最近，由近及远依次为第2磨牙、第1磨牙、第3磨牙、第2前磨牙和第1前磨牙；下颌磨牙的远中根至下颌管的距离均较近中根近。第1前磨牙、第2前磨牙、第1磨牙、第2磨牙、第3磨牙牙根至下颌管上壁的最短距离分别为(8.38±1.04) mm(左)和(8.44±1.05) mm(右)、(7.51±0.85) mm、(3.40±　0.65) mm、(2.93±0.61) mm、(3.92±0.63) mm(左)和(3.97±0.63) mm(右)。  结论　下颌管的三维重建对选择适宜长度的牙种植体，避免牙种植体损伤下牙槽神经等具有重要意义。

Objective　To provide anatomic basis for the mandibular dental implantation.　Methods　20 volunteers with healthy teeth were selected and scanned in series by spiral CT from the orbitomeatal line (OML). The mandibular canal was reconstructed by the curve-planar reconstruction(CPR) under the ADW 4.2 software. The position and composition of mandibular canal were observed, followed by the measurement of the distance from the dental root of mandibular posterior teeth to the superior wall of mandibular canal. The visual model of mandible and mandibular canal were reconstructed by the Amira 3D software. The course of mandibular canal in the diaphanous mandible and the relationship of mandibular posterior teeth with it were detected.　Results　The mandibular canal was composed of a thin compact bone and traveled through the bottom of lingual side of the molar and buccal side of the premolar. The lingual side of the madibular canal was thicker than that of other sides. In the diaphanous mandible, the mandibular canal could be clearly displayed, including its position, shape and course, and the distances from the mandibular canal to the inferior edge of mandibular body, alveolar crest and the medial, lateral plates of mandible respectively. The distance from the dental root of second molar to the mandibular canal was the nearest than that of the others, and the followed was the second molar, first molar, third molar, second premolar and first premolar by the near and far. The distance was nearer from the distal root of mandibular molar to the mandibular canal than that of the mesial root. The nearest distance from the dental root of first premolar, second premolar, first molar, second molar, third molar to the superior wall of mandibular canal were (8.38±1.04) mm(left) and (8.44±1.05) mm(right), (7.51±0.85) mm, (3.40±0.65) mm, (2.93±0.61) mm, (3.92±0.63) mm(left) and (3.97±0.63) mm(right) separately.　Conclusions　Three-dimensional reconstruction and analysis of mandibular canal is valuable for choosing appropriate length of dental implantation and avoiding to injury the inferior alveolar nerve during the operation.