目的: 通过3D打印技术建立带有不规则结构(Hus&Kim Ⅴ型、Yin Ⅱ型峡部)的根管模型，并利用切片和影像学手段评价单尖根管充填的效果，以期对临床应用单尖根管充填技术提供参考。方法: (1) 纳入具备Hus&Kim Ⅴ型、Yin Ⅱ型峡部根管结构的人离体前磨牙，使用锥形束计算机断层扫描(cone-beam computed tomography, CBCT)并重建根管系统，设计打印标准化3D根管模型，并用罗丹明B染色和偏差拟合验证模型可用性。(2)将30个模型随机分为3组(n=10)，使用不同充填方法进行根管充填，分别为对照组：热垂直加压充填组；实验组1：0.06锥度(30#)单尖充填组；实验组2：0.04锥度(35#)单尖充填组，均采用多组分混合根管封闭剂(GuttaFlow 2)。样本储存1周后，在距根尖2、4、6、8 mm处进行横切片，体式显微镜下观察，计算充填率和充填物构成比。(3)在上述结果基础上，选择充填率较高的实验组1(n=4)与对照组(n=4)通过微计算机断层扫描(micro-computed tomography，Micro-CT)进一步分析充填效果，测量根管系统、主根管及峡部内充填物体积，并计算体积充填率。采用两因素多元方差分析评估差异，并通过Tukey’ s检验对各组数据进行组间和组内两两比较。结果: (1) 用罗丹明B染色后可见染色液从模型根尖孔溢出，染色范围达主根管系统及峡部区域，切片显示无残余支撑材料，打印模型偏差为0.03 mm，拟合平均距离为0.02 mm，证实模型可用。(2)实验组1和2在距根尖4、6、8 mm层面上的充填率均低于对照组，差异具有统计学意义(F=45.04，P＜0.01)。两实验组在根尖2、4 mm处的充填率差异无统计学意义(P＞0.01)，但在根管中上段6、8 mm处，实验组1的充填率高于实验组2(P＜0.01)。同一实验组内，根尖区2、4 mm处的充填率均低于根管中上段6、8 mm处(P＜0.01)。两实验组在根尖段2、4 mm的牙胶及封闭剂占比差异无统计学意义(F=2.383，P＞0.01)，根尖2 mm处牙胶占比较大，根尖4 mm处封闭剂占比较大(P＜0.01)。(3)Micro-CT扫描结果显示，实验组1与对照组的体积充填率之间的差异具有统计学意义(F=47.33，P＜0.01)，其中在峡部结构中，实验组1的体积充填率为54.33%±4.35%，在主根管内为78.31%±4.21%，均低于对照组的峡部体积充填率76.48%±4.89%和主根管体积充填率86.90%±3.29%(P＜0.01)，实验组1的体积充填率在主根管高于峡部(P＜0.01)，而对照组在峡部与主根管之间的差异无统计学意义(P＞0.01)。结论: 在带有峡部的不规则根管结构中，使用大锥度牙胶尖可改善单尖根管充填在根管中上段的充填效果，但峡部的体积充填率仍低于主根管，需进一步改进技术。

Objective: To evaluate the filling quality of single cone obturation in root canal model with irregular structure (Hus&Kim Ⅴ, Yin Ⅱ-type isthmus) which established by 3D printing technology using slices and radiographic methods, in order to provide reference for clinical practice. Methods: (1) Extracted fresh premolars with Hus&Kim Ⅴ and Yin-type Ⅱ isthmus were collected and scanned by cone-beam computed tomography (CBCT), then standard root canal models were designed and printed. Rhodamine B staining and bias fitting were used to verify the availability of the models. (2) 30 root canal models were randomly divided into 3 groups according to different filling methods (n=10). Control group: vertical compaction obturation; Experimental group 1: single cone obturation with 0.06-taper cone (30#); Experimental group 2: single cone obturation with 0.04-taper cone (35#), GuttaFlow 2 as canal sealers. Slices were taken at 2, 4, 6, and 8 mm from the root apex in the direction perpendicular to the long axis of the root and observed under a stereomicroscope to calculate the percentage of filling area (PAV), percentage of gutta-percha-filled area (PGFA), percentage of sealer filled area (PSFA). (3) On the basis of the above results, two groups (n=4) were selected to further analyze the filling quality by micro-computed tomography (Micro-CT), the filling volume of main root canal and the isthmus were obtained, and the percentage of filling volume (PFV) was calculated. Two-way ANOVA was used to evaluate the differences between the groups, and Tukey' s multiple comparison was used to compare the data between the groups and within the groups. Results: (1) Rhodamine B staining solution could overflow the apical foramen, and the main root canal system and the isthmus area were stained, showed no remnants of support material. The 3D standard deviation of the printed model data was 0.03 mm, and the average fitting distance was 0.02 mm. (2) The PFA of the two experimental groups were both significantly lower than that of the control group (F=45.04, P < 0.01). There was no statistical difference of the PFA at apical 2 and 4 mm between the two experimental groups (P>0.01), but at the middle and coronal portions of the root canal (6, 8 mm), the PFA of the experimental group 1 was higher than that of the experimental group 2 (P < 0.01). PFA in the apical 2, 4 mm of the two experimental groups were both lower than that in the middle and coronal portions 6, 8 mm of the canal (P < 0.01). There was no difference in the PGFA and PSFA between the two experimental groups at the apical 2, 4 mm (F=2.383, P>0.01). (3) The results of Micro-CT showed that the PFV of the experimental group 1 was statistically different with the control group (F=47.33, P < 0.01). The PFV of the experimental group 1 was 54.33%±4.35% in the isthmus and 78.31%±4.21% in the main root canal, which were both lower than the PFV of the control group of 76.48%±4.89% (isthmus) and 86.90%±3.29% (main root canal, P < 0.01). The PFV of the main root canal in the experimental group 1 was higher than that in the isthmus (P < 0.01), while there was no difference between the isthmus and the main root canal in the control group (P>0.01). Conclusion: In the irregular root canal structure with isthmus, using large-taper gutta-percha can improve the filling quality of the middle and upper part of the canal, but the percentage of filling volume in the isthmus is lower than that of the main canal, and more technical improvements are needed.