Intradentinal antimicrobial action and filling quality promoted by ultrasonic agitation of epoxy resin-based sealer in endodontic obturation

Abstract The aim of this study was evaluate the influence of ultrasonic activation (UA) of AH Plus to improve canal and isthmus filing, and analyse the antimicrobial effect against Enterococcus faecalis within dentinal tubules. Material and Methods: Thirty mesial roots of mandibular first molars were selected and divided into 2 groups (n = 15): with and without UA of the sealer. Then the root canals were filled by using the single cone technique, and the specimens were sectioned at 2, 4 and 6 mm from the apex for stereomicroscope and confocal laser scanner microscopy (CLSM) analysis. In addition, 30 bovine incisors were contaminated with Enterococcus faecalis and divided into 3 groups (n = 10). The specimens were obturated by using the single cone technique with (G1) and without (G2) UA of the sealer and G3 as the control group. All were sectioned into 6 mm-long cylinders and stained with LIVE/DEAD to assess bacterial viability by CLSM. Results: The UA of the sealer significantly reduced the presence of unfilled areas in the canal and isthmus area in all sections (p<0.05), and there was a significant increase in sealer penetration in both canals and isthmuses (p<0.05). As regards gaps, a significant reduction was found at 2 and 6 mm in the isthmus area of the UA group (p<0.05). Moreover, UA of the sealer significantly reduced bacterial viability in the superficial dentine when compared with the other groups (p<0.05). Conclusion: Ultrasonic activation of the AH Plus sealer promoted a better quality of root canal filling and increased the intratubular penetration of sealer, especially in the isthmus area. Additionally, ultrasonic activation of the sealer increased the intradentinal antimicrobial action against Enterococcus faecalis, mainly in the superficial dentine of the root canal.

摘要 本研究旨在评估AH Plus根管封闭剂（AH Plus sealer）的超声激活（Ultrasonic Activation, UA）对根管及峡部充填效果的改善作用，并分析其对牙本质小管内粪肠球菌（Enterococcus faecalis）的抗菌效果。材料与方法：选取30颗下颌第一磨牙近中根，分为2组（n=15），分别采用超声激活与未激活的封闭剂，随后采用单锥技术（single cone technique）完成根管充填。将标本于距根尖2、4、6 mm处切片，用于体视显微镜及共聚焦激光扫描显微镜（Confocal Laser Scanning Microscopy, CLSM）分析。此外，选取30颗牛切牙，接种粪肠球菌后分为3组（n=10）：G1组采用超声激活的封闭剂行单锥充填，G2组采用未激活的封闭剂，G3为空白对照组。所有标本均被切割为6 mm长的圆柱状试件，使用活/死染色剂（LIVE/DEAD）染色，通过CLSM评估细菌活力。结果：超声激活封闭剂可显著减少所有切片区域内根管及峡部的未充填区域（p<0.05），并显著提升封闭剂在根管与峡部内的渗透深度（p<0.05）。针对充填间隙问题，超声激活组在峡部区域的2 mm及6 mm处间隙显著减少（p<0.05）。此外，相较于其余两组，超声激活封闭剂可显著降低表层牙本质内的细菌活力（p<0.05）。结论：AH Plus封闭剂的超声激活可提升根管充填质量，增强封闭剂在牙本质小管内的渗透能力，尤其在峡部区域效果显著。同时，该处理可增强针对粪肠球菌的牙本质内抗菌作用，尤以根管表层牙本质为明显。