基于锥形束CT的下牙槽神经管走行测量分析

Measurement and analysis of the course of the mandibular canal based on cone⁃beam computed tomography

目的通过锥形束CT(CBCT)分析下牙槽神经在下颌后牙区的走向。方法收集2018年2月至2021年6月云南省临沧市凤庆县人民医院口腔科CBCT数据77例,对CBCT数据进行回顾性研究,将CBCT数据进行三维重建后截取左右两侧下颌第二前磨牙、第一磨牙、第二磨牙各牙根最低点的冠状面图像进行测量,包括下牙槽神经管中心点到下颌骨最下缘点的垂直距离,到处于同一水平线颊侧点的距离,到处于同一水平线舌侧点的距离,以及牙槽神经管最上缘点到根尖点的垂直距离,采用两独立样本t检验比较不同性别同一位点下牙槽神经管与下颌骨各方向骨壁的距离。结果(1)男性下牙槽神经管与下颌骨下缘间的距离大于女性。男性右下第二前磨牙位点(11.2±1.7)mm、女性为(10.2±1.2)mm,差异有统计学意义(t=3.123,P=0.003);男性右下第二磨牙远中根位点(10.8±1.7)mm、女性为(10.1±1.6)mm,差异有统计学意义(t=2.133,P=0.036)。(2)下牙槽神经管到下颌骨颊侧骨壁的距离在第一、第二磨牙上明显大于舌侧距离。男性右下颌第一磨牙近中根位点,颊侧(6.6±1.6)mm、舌侧(3.6±1.3)mm,差异有统计学意义(t=9.181,P<0.001),女性同一位点,颊侧(6.4±1.2)mm、舌侧(3.8±1.0)mm,差异有统计学意义(t=9.950,P<0.001);男性右下颌第二磨牙远中根位点颊侧(8.3±1.4)mm、舌侧(3.4±1.0)mm,差异有统计学意义(t=18.57,P<0.001),女性同一位点,颊侧(7.8±1.5)mm、舌侧(3.7±1.3)mm,差异有统计学意义(t=16.90,P<0.001);在第二前磨牙上两者差距不大。除了右侧第一磨牙远中根(Ⅲ区)、右侧第一磨牙近中根(Ⅳ区)观测点外,其余观测点均可见下牙槽神经管与根尖距离上男性大于女性。结论下牙槽神经管在下颌骨内的走行,在垂直向呈现一定的曲线,在颊舌向较为规律。

Objective To analyze the course of the mandibular canal in the posterior mandibular region using cone⁃beam computed tomography(CBCT).Methods The CBCT data of 77 cases in the Department of Stomatology at the People′s Hospital of Fengqing County,Lincang City,Yunnan Province,from February 2018 to June 2021,were used.After three⁃dimensional reconstruction of the CBCT data,coronal images of the roots of the second premolars,first molars,and second molars were measured.The measurements included the vertical distance from the center of the mandibular canal to the lower margin of the mandible,to the buccal and lingual walls on the same horizontal plane,and the vertical distance from the upper margin of the mandibular canal to the apex,using an independent two⁃sample t⁃test to compare the distances between the alveolar nerve canal and the mandibular bone walls in males and females.Results The distance between the mandibular canal and the lower margin of the mandible was greater in males than that in females.This distance at the right lower second premolar point was(11.2±1.7)mm in males,and(10.2±1.2)mm in females,which was statistically different between genders(t=3.123,P=0.003).The distance at right lower second molar distal root point was(10.8±1.7)mm in males,and(10.1±1.6)mm in females,which was statistically different between genders(t=2.133,P=0.036).The distance from the mandibular canal to the buccal wall of the mandible was significantly longer than that to the lingual wall at the first and second molars,with the exception of the second premolars.The distance at the buccal side of the distal root point of the lower right first molars in males was(6.6±1.6)mm,and the distance at the lingual side was(3.6±1.3)mm,which was statistically different between the two sides(t=9.181,P<0.001).The distance at the buccal side in females was(6.4±1.2)mm,and at the lingual side was(3.8±1.0)mm,which was statistically different between the two sides(t=9.950,P<0.001).The distance at the buccal side of distal root point of the lower right second molars in males was(8.3±1.4)mm,and the distance at the lingual side was(3.4±1.0)mm,which was statistically different between the two sides(t=18.57,P<0.001).This distance at the buccal side in females was(7.8±1.5)mm,and the distance at the lingual side was(3.7±1.3)mm,which was statistically different between the two sides(t=16.90,P<0.001).The distance from the mandibular canal to the apex was longer in males than that in females on the other observation points except for the distal roots of the right first molars(ZoneⅢ),and the mesial roots of the right first molars(ZoneⅣ).Conclusion The course of the mandibular canal within the mandible exhibited a certain curve in the vertical direction,with a more regular pattern in the buccolingual direction.