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根管封闭剂的超声活化（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），分别采用超声活化封闭剂与未活化封闭剂进行根管充填。随后采用单尖法（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 scanner 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组采用超声活化封闭剂行单尖法充填，G2组采用未活化封闭剂行单尖法充填，G3为对照组。所有标本均制备为6 mm长的圆柱状切片，使用LIVE/DEAD染色法，通过CLSM评估细菌活性。
结果：超声活化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及峡部内的渗透深度（p<0.05）。在缝隙方面，超声活化组峡部区域在2 mm和6 mm处的缝隙显著减少（p<0.05）。此外，与其他组相比，超声活化封闭剂可显著降低表层牙本质内的细菌活性（p<0.05）。
结论：AH Plus封闭剂的超声活化可提升根管充填质量，增强封闭剂的牙本质小管内渗透效果，尤其在峡部区域。此外，超声活化封闭剂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最为显著。