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目的运用显微计算机断层扫描(micro-CT,M-CT)三维重建后研究不同年龄组下颌第一前磨牙单根管初始锥度。方法采用随机数字表法选取牙根完整,未进行过牙髓治疗的单根管离体下颌第一前磨牙58颗,分为13～25岁、26～45岁和46～60岁组,采用Micro-CT扫描重建。再将每颗牙根平均分为3段,包括根颈、根中和根尖,通过Mimics10.01软件测量根管的近远中向及颊舌向管径,分别计算根管3段近远中向和颊舌向根管锥度。结果颊舌向3段根管锥度的13～25岁组与26～45岁组有统计学差异,13～25岁组与46～60岁组有统计学差异(P<0.05),而26～45岁与46～60岁组3段锥度只有根中段有差异(P<0.05);近远中向3段锥度的13～25岁组与46～60岁组均有统计学差异(P<0.05),而26～45岁与46～60岁组仅根颈段有统计学差异(P<0.05),13～25岁与26～45岁组只有根尖段有统计学差异(P<0.05)。结论单根管下颌第一前磨牙中,不同年龄组有不同的根管原始锥度;可指导临床根管预备器械的选择。
Objective To study the initial taper of single-root canal of mandibular first premolar in different age groups after three-dimensional reconstruction by micro-computed tomography (M-CT). Methods A total of 58 intact mandibular first premolar teeth with intact roots and without endodontic treatment were selected by random number table. They were divided into 13 ~ 25 years old, 26 ~ 45 years old and 46 ~ 60 years old group. Micro- -CT scan reconstruction. Then each root was divided into three sections equally, including the root neck, root and root tip. The distal and mid-length of the root canal and the bucco-lingual diameter of the root canal were measured by Mimics 10.01 software. Tendons to the buccal tongue taper. Results There were significant differences between the 13 ~ 25 age group and the 26 ~ 45 age group in the three - stage root canal conusation. The differences between the 13 ~ 25 age group and the 46 ~ 60 age group were statistically significant (P <0.05) There was a significant difference in the three segments of conicity between the 45-year-old group and the 46- to 60-year-old group (P <0.05), while there was a significant difference between the three groups of 13-25-year group and the 46-60-year group (P <0.05). There was significant difference in the apical segment between the age group of 13 ~ 25 and the age group of 26 ~ 45 (P <0.05) . Conclusions In the first premolar of single root canal and mandible, there are different initial conicities of root canal in different age groups; it can guide the choice of clinical root canal preparation equipment.