AIM To assess the impact of conservative endodontic access cavities (CEC) and truss access cavities (TAC) during root canal treatment performed on mandibular molars in terms of: ability to shape and fill root canals, microbial reduction in canals, and cleaning of the pulp chamber. In addition, the fracture resistance of the teeth after coronal restoration was assessed. Traditional endodontic cavities (TEC) were used as a reference technique for comparison. METHODOLOGY Thirty extracted intact mandibular molars were scanned in a microcomputed tomography device (micro-CT), matched based on similar anatomical features and assigned to TEC, CEC or TAC groups (n = 10). The specimens were accessed accordingly, and root canals were contaminated with bacterial suspensions of Enterococcus faecalis (21 days). Subsequently, the first microbial sample was collected from root canals (S1). The canals were initially prepared with Reciproc Blue R25 instrument followed by a second instrumentation using Reciproc Blue R40. Eight mL of 0.5% NaOCl were used as an irrigant for each instrument. A final irrigation protocol was performed with 2 mL of 0.5% NaOCl, 2 mL of 17% EDTA and another 2 mL of 0.5% NaOCl. Microbial samples were collected from root canals after R25 (S2), R40 (S3) and final irrigation (S4). The teeth were rescanned after S4. Then, root canals were filled, rescanned, restored and the teeth subjected to fracture resistance tests. The statistical analysis was performed with type I negative binomial and beta 0-1 inflation regression models for microbiological analysis. Instrumentation, filling and resistance to fracture results were subjected to anova and Tukey tests (P < 0.05). RESULTS S4 revealed no significant variations in microbial reduction amongst the groups (P > 0.05). TEC had a significantly lower percentage of unprepared surface area than CEC (P < 0.05). No differences were found regarding the percentage of dentine removed, transportation, centring ability and filling voids amongst the groups (P > 0.05). The TEC group had a significantly lower volume of remaining root filling material within the pulp chamber than CEC and TAC groups (P < 0.05). There was no difference regarding fracture resistance amongst the groups (P > 0.05). CONCLUSION Conservative access cavities did not offer any advantage in comparison with the traditional endodontic cavities in any of the parameters considered. Furthermore, conservative methods were associated with larger percentages of unprepared canal surface area and larger volumes of remaining root filling material within the pulp chamber.

中文翻译：

---

根管入口腔腔设计对下颌磨牙根管器械的功效，微生物减少，根管充盈和抗断裂性的影响。

目的评估在根管治疗过程中保守性牙髓进入腔（CEC）和桁架进入腔（TAC）对下颌磨牙的影响，包括：塑造和填充根管的能力，减少根管中的微生物以及清洁牙髓的能力室。另外，评估了冠状修复后牙齿的抗断裂性。传统牙髓腔（TEC）用作比较的参考技术。方法学在微型计算机断层扫描设备（micro-CT）中扫描30个完整的下颌磨牙，根据相似的解剖特征进行匹配，并分配给TEC，CEC或TAC组（n = 10）。相应地取入标本，并且用粪肠球菌的细菌悬浮液污染了根管（21天）。后来，从根管中收集第一个微生物样品（S1）。最初使用Reciproc Blue R25器械准备运河，然后使用Reciproc Blue R40进行第二器械。八毫升的0.5％NaOCl用作每种仪器的冲洗液。最后的冲洗程序是用2 mL的0.5％NaOCl，2 mL的17％EDTA和另外2 mL的0.5％NaOCl进行的。在R25（S2），R40（S3）和最终灌溉（S4）之后，从根管中收集微生物样品。在S4之后重新扫描牙齿。然后，对根管进行填充，重新扫描，修复，并对牙齿进行抗断裂测试。统计分析使用I型阴性二项式和β0-1膨胀回归模型进行微生物分析。仪器仪表 填充和抗断裂性能均接受方差分析和Tukey测试（P <0.05）。结果S4显示各组之间的微生物减少没有显着差异（P> 0.05）。TEC的未准备表面积百分比显着低于CEC（P <0.05）。各组之间牙本质去除率，运输，定心能力和填充空隙的差异均无统计学意义（P> 0.05）。与CEC和TAC组相比，TEC组的牙髓腔内残留的根部填充材料的体积明显减少（P <0.05）。各组之间的抗断裂性没有差异（P> 0.05）。结论在考虑的任何参数方面，与传统的牙髓腔相比，保守性腔不能提供任何优势。此外，