目的·观察不同年龄下颌单根管第一前磨牙根管的三维形态。方法·选取15~25岁因正畸需要拔除的下颌单根管第一前磨牙（青年组）和55~75岁因牙周病需拔除的单根下颌第一前磨牙（老年组），每组10颗。利用微型CT扫描获取数据，采用CTAn软件分析牙根体积、根管体积、根管面积以及结构模型系数（SMI）。结果·青年组和老年组根管的平均总体积分别为（12.308±4.550）mm3和（3.798±0.944） mm3，根管总面积分别为（48.869±8.064）mm2和（25.187±5.072） mm2，差异均有统计学意义(P<0.05)。2组根管下1/3和根管中1/3平均相对体积分数的差异有统计学意义(P<0.05)。老年组SMI值显著大于青年组(P<0.05)。结论·对不同年龄患者进行根管治疗时，要加强对其根管解剖形态的了解，重视根管预备，提高根管治疗的成功率。

Objective·To observe the three dimensional morphology of root canal of mandibular first premolars with single canal for individuals at different ages. Methods·Ten mandibular first premolars with single canal that needed to be extracted due to orthodontic reason from individuals aged 15-25 years (the young group) and ten mandibular first premolars with single canal that needed to be extracted due to periodontal diseases from individuals aged 55-75 years (the elderly group) were selected. Data were gathered by Micro-CT scanning and CTAn software was used to analyze root volume, canal volume, canal area, and structure model index (SMI). Results·Average canal volume and area were (12.308±4.550) mm3 and (48.869±8.064) mm2 in the young group and (3.798±0.944) mm3 and (25.187±5.072) mm2 in the elderly group. The differences were both statistically significant (P<0.05). The differences in average volume fractions of middle and apical third of root canals were statistically significant (P<0.05). The elderly group has a significantly higher SMI than the young group (P<0.05). Conclusion·For the treatment of patients at different ages, we need to thoroughly understand anatomic characteristics of root canals, pay more attention to root canal preparation, so as to improve the success rate of root canal treatment.