Final irrigation protocols can be used to promote stable long-term bond strength of AH Plus to dentin

Abstract Irrigation solutions might affect dentin surface characteristics and, consequently, endodontic sealers adhesion. Objective This study analyzed the effect of different final irrigation protocols on push-out bond strength (BS) of AH Plus to dentin seven days and 20 months after obturation. Scanning electron micrographs were obtained from the dentin surface of one sample/group after final irrigation. Methodology Canals of bovine incisors were instrumented and received final irrigation with (n=21): G1 – 2.5% sodium hypochlorite (NaOCl) + distilled water; G2 – 2.5% NaOCl + 17% EDTA; G3 – 2.5% NaOCl + 17% EDTA + 2.5% NaOCl; G4 – 2.5% NaOCl + 17% EDTA + 2% chlorhexidine (CHX); G5 – mixture 5% NaOCl + 18% etidronate (HEDP); and G6 – mixture 5% NaOCl + 10% tetrasodium EDTA (Na4EDTA). After irrigation, one root/group was split and images were obtained by scanning electron microscopy (SEM). The other 20 roots/group were filled with only AH Plus sealer. Three slices/root were used for push-out assessment seven days and 20 months after obturation. One-way analysis of variance and Tukey (α<0.05) were used to compare the results among experimental groups, and unpaired t-test (α<0.05) was used to compare the results of the same group over time. Results The photomicrographs showed that, excepting G1, all groups completely removed the smear layer from the samples. In G2 and G4, the opening of the dentin tubules enlarged. In G3, erosion was observed in the peritubular and intertubular dentin. Values of the BS in the seven days were G2=G3=G4=G5>G6=G1 and in the 20 months were G3=G5>G6=G4>G1=G2. G3, G5, and G6 presented values of BS in 20 months similar to the values of seven days (P>0.05). Conclusions The final irrigation protocols tested produced dentin surfaces with different characteristics. Only G3 and G5 presented high BS values that were stable over time.

摘要 根管最终冲洗方案可能会影响牙本质表面特性，进而影响根管封闭剂的黏结性能。
目的 本研究探讨不同最终根管冲洗方案对AH Plus根管封闭剂在根管充填后7天及20个月时的推送黏结强度（push-out bond strength，BS）的影响。本研究通过扫描电子显微镜（scanning electron microscopy，SEM）对每组1个接受最终根管冲洗的样本的牙本质表面采集图像。
方法 对牛切牙根管进行根管预备后，采用以下6种方案实施最终根管冲洗（每组n=21）：G1——2.5%次氯酸钠（sodium hypochlorite，NaOCl）+蒸馏水；G2——2.5%次氯酸钠（NaOCl）+17%乙二胺四乙酸（ethylenediaminetetraacetic acid，EDTA）；G3——2.5%次氯酸钠（NaOCl）+17%乙二胺四乙酸（EDTA）+2.5%次氯酸钠（NaOCl）；G4——2.5%次氯酸钠（NaOCl）+17%乙二胺四乙酸（EDTA）+2%氯己定（chlorhexidine，CHX）；G5——5%次氯酸钠（NaOCl）与18%依替膦酸（etidronate，HEDP）的混合液；G6——5%次氯酸钠（NaOCl）与10%乙二胺四乙酸四钠（tetrasodium EDTA，Na4EDTA）的混合液。冲洗完成后，每组取1个牙根进行劈裂，通过扫描电子显微镜（SEM）获取图像。剩余每组20个牙根仅使用AH Plus根管封闭剂进行根管充填。每个牙根切取3个切片，分别在充填后7天及20个月时进行推送黏结强度测试。采用单因素方差分析及Tukey检验（α<0.05）比较各组间的实验结果，采用非配对t检验（α<0.05）比较同一组在不同时间点的实验数据。
结果 扫描电镜图像显示，除G1组外，其余各组均完全去除了样本表面的玷污层。G2与G4组的牙本质小管开口出现扩张；G3组的管周牙本质及管间牙本质可见侵蚀现象。充填后7天时的黏结强度排序为：G2=G3=G4=G5>G6=G1；充填后20个月时的黏结强度排序为：G3=G5>G6=G4>G1=G2。G3、G5及G6组在20个月时的黏结强度值与7天时相比无显著差异（P>0.05）。
结论 本研究所测试的各类最终根管冲洗方案可使牙本质表面呈现不同的特性。仅G3与G5组可获得较高且随时间保持稳定的推送黏结强度。