【目的】通过影像法（X线、CBCT及Micro-CT）和微渗漏法，探究PUMCH改良根管充填技术在离体牙样本的根管充填效果和根尖封闭效果，验证PUMCH改良根管充填技术的临床可行性。

【方法】筛选符合实验标准的离体牙，建立髓腔入路后，进行根管机械预备、Er:YAG激光激活荡洗。随机分组进行根管充填：A. PUMCH改良根管充填技术（简称“PUMCH组”）；B. 单尖法根管充填技术（简称“单尖法组”）；C. 冷牙胶侧方加压根管充填技术（简称“冷侧压组”）；D. 热牙胶垂直加压根管充填技术（简称“热垂压组”）。用玻璃离子水门汀封闭实验样本的冠方通路，并将标本储存于37 ℃、100%的恒温箱中1周以使充填材料完全固化。以上离体牙样本预处理完成后，分别进行以下实验。（1）影像法：将充填完成的离体牙样本，进行X线扫描，评估根管充填的长度、密度和锥度；进行CBCT扫描，评估根管充填材料末端至根尖孔的距离、根管充填材料内气泡比例及最大气泡直径；进行Micro-CT扫描，评估根管系统的整体充填率及欠填率、进一步探究影响欠填的因素（糊剂气泡因素和复杂解剖因素）。对X线、CBCT和Micro-CT的影像结果进行统计分析。（2）微渗漏法：将充填完成的离体牙样本，置于硝酸银微渗漏模型，之后于根尖4mm获得横断切片，将“圆形或类圆形形态根管”归类为简单解剖结构根管，将“包含侧副根管及峡部等结构的根管”归类为复杂解剖结构根管。电镜下观察各切片样本充填材料的间隙和银离子微渗漏程度并对根尖封闭效果评分，对简单解剖结构根管和复杂解剖结构根管的根尖封闭效果进行统计分析。

【结果】（1）X线结果：比较各实验组X线影像的根管充填长度、密度和锥度，热垂压组长度评分低于其他三组，冷侧压组密度评分低于其他三组，PUMCH组锥度评分低于其他三组，但各实验组的根管充填长度、密度和锥度临床评分无统计学差异(P > 0.05)。（2）CBCT结果：比较各实验组根管充填材料末端至影像学根尖孔的距离，结果显示各组间结果无统计学差异(P > 0.05)。比较各实验组根管充填材料内部气泡比例和最大气泡直径，结果显示PUMCH组的糊剂气泡与其他三组均有统计学差异（P＜0.05）。（3）Micro-CT结果：比较各实验组的整体充填率和整体欠填率、影响充填效果因素（糊剂气泡和复杂解剖结构）的欠填率、以及分析复杂解剖结构（根管峡部和根管侧支）的欠填率，结果显示PUMCH组的整体充填率、整体欠填率和糊剂气泡欠填率与其他实验组均有统计学差异（P＜0.05）。（4）微渗漏实验结果：对于简单解剖结构根管，各实验组根尖封闭效果无统计学差异（P>0.05）。对于复杂解剖结构根管，通过Kruskal-Wallis H检验评估各实验组间整体差异，结果显示各实验组间存在统计学差异（P＜0.05）。采用Mann-Whitney U检验（Bonferroni校正）进一步进行组间对比，结果显示PUMCH组与冷侧压组、热垂压组有统计学差异（P＜0.05），与单尖法组无统计学差异（P>0.05）。

【结论】（1）对于简单解剖结构根管，PUMCH改良根管充填技术与其他根管充填技术的充填效果（长度、密度和锥度，以及根管充填材料末端至影像学根尖孔的距离）无显著差异；但对于复杂解剖结构根管，PUMCH改良根管充填技术的整体充填率显著高于其他根管充填技术，且该技术可有效降低根管糊剂气泡因素（充填材料内部气泡比例、最大气泡直径，以及糊剂气泡引起的欠填率）对充填效果的负面影响。（2）对于简单解剖结构根管，PUMCH改良根管充填技术可与其他根管充填技术达到相同的根尖封闭效果；但对于复杂解剖结构根管，PUMCH改良根管充填技术在根尖封闭效果上具有显著优势。

Objective:To evaluate the sealing efficacy of the novel root canal obturation technique in PUMCH therapy through multimodal imaging analysis (X-ray, CBCT, Micro-CT) and microleakage assessment in extracted human teeth, with the aim of validating its clinical feasibility.

Methods:Extracted teeth meeting experimental criteria were selected. After establishing coronal access, root canals were mechanically prepared and subjected to Er:YAG laser-assisted irrigation. Specimens were randomly assigned to four obturation groups: (A) novel root canal obturation technique in PUMCH therapy, (B) single cone filling group, (C) cold lateral compaction group, and (D) warm vertical compaction group.The coronal access of experimental samples was sealed with glass ionomer cement, and specimens were incubated at 37 ℃ and 100% humidity for 1 week to ensure complete curing of the obturation materials. The following experiments were conducted:

（1）Imaging Methods:Filled extracted teeth were scanned via X-ray to evaluate post-operative root filling length, density, and taper; via cone-beam computed tomography (CBCT) to assess the distance from the root filling material apex to the radiographic apical foramen, the proportion of air bubbles within the filling material and the maximum bubble diameter; and via micro-computed tomography (Micro-CT) to measure overall root canal system filling rate and underfilling rate, and further explore factors influencing underfilling (sealer bubble factors and complex anatomical factors). Imaging results from X-ray, CBCT, and Micro-CT were statistically analyzed.

（2）Microleakage Method:Filled extracted teeth were subjected to a silver nitrate microleakage model. Transverse sections were obtained at 4 mm from the root apex. Root canals with round or subround morphology were classified as simple anatomical structures, while those containing lateral accessory canals, isthmuses, or other complex structures were classified as complex anatomical structures. Under an electron microscope, the gap between obturation materials and silver ion microleakage degree in each section were observed, and apical sealing effectiveness scores were assigned. Scores for apical sealing in simple and complex anatomical root canals were statistically analyzed.

Results:

(1) X-ray Analysis: Comparisons of root filling length, density, and taper scores across groups showed that the warm vertical compaction group had lower length scores than the other three groups, the cold lateral compaction group had lower density scores, and the PUMCH group had lower taper scores. However, there were no statistically significant differences in clinical scores for root filling length, density, or taper among groups (P > 0.05).

(2) CBCT Assessment: No significant differences were observed in the distance from the root filling material apex to the radiographic apical foramen across groups (P > 0.05). Comparisons of air bubble proportion and maximum bubble diameter within filling materials revealed statistically significant differences in sealer bubble rates between the PUMCH group and the other three groups (P < 0.05).

(3) Micro-CT Evaluation: Analyses of overall filling rate, overall underfilling rate, underfilling rates due to influencing factors (sealer bubbles and complex anatomical structures), and underfilling rates in complex anatomical structures (root canal isthmuses and lateral canals) showed that the PUMCH group differed significantly from other groups in overall filling rate, overall underfilling rate, and underfilling rate due to sealer bubbles (P < 0.05).

(4) Microleakage Testing: For root canals with simple anatomical structures, no significant differences in apical sealing effectiveness were observed among groups (P > 0.05). For complex anatomical structures, Kruskal-Wallis H test revealed overall statistical differences among groups (P < 0.05). Post-hoc Mann-Whitney U tests with Bonferroni correction showed significant differences in apical sealing scores between the PUMCH group and both the cold lateral compaction group and warm vertical compaction group (P < 0.05), but no significant difference with the single cone filling group (P > 0.05).

Conclusion:

(1) For root canals with simple anatomical structures, the novel root canal obturation technique in PUMCH therapy exhibited comparable root filling efficacy (length, density, taper, and distance from the root filling material apex to the radiographic apical foramen) to other obturation techniques. However, for root canals with complex anatomical structures, this technique achieved significantly higher overall filling rates and effectively reduced the negative impact of sealer bubble-related factors (proportion of air bubbles within filling materials, maximum bubble diameter, and underfilling rate caused by sealer bubbles) on obturation efficacy.

(2) For simple anatomical root canals, the novel root canal obturation technique in PUMCH therapy achieved comparable apical sealing effectiveness to other obturation techniques. For complex anatomical root canals, however, it demonstrated significant advantages in apical sealing effectiveness.