目的：研究根管治疗过程中次氯酸钠（sodium hypochlorite，NaOCl）冲洗溶液对牙本质粘接强度的影响。方法： 选取新鲜拔除的人第三磨牙15颗，牙冠完整无龋坏，未经牙体或牙髓治疗,去除釉质，暴露中层牙本质，600目砂纸打磨牙本质表面1 min，去离子水冲洗1 min，制备牙本质平面试件。试件随机分为3组，采用不同表面处理方法后制作粘接试件：A组（阴性对照组），去离子水处理牙本质平面试件20 min；B组（2.50% NaOCl实验组），2.50% NaOCl溶液处理牙本质平面试件20 min，每5分钟更换1次新鲜溶液；C组（5.25% NaOCl实验组）， 5.25% NaOCl溶液处理牙本质平面试件20 min，每5分钟更换1次新鲜溶液。处理后所有试件表面均使用自酸蚀粘接剂SE bond进行粘接处理，上方堆塑5 mm高的AP-X复合树脂，分层固化后，粘接试件置于37 ℃去离子水中储存24 h后，使用金刚石切割机垂直于粘接界面切割，制作1.0 mm×1.0 mm条状试样（n=45）。用微拉伸测试仪测试条状试样微拉伸粘接强度（MPa）， 体视显微镜下观察试样断裂类型（界面破坏、内聚破坏及混合破坏类型），采用单因素方差分析比较不同实验组的微拉伸粘接强度，并用Post-hoc test（LSD）法进行两两比较，应用卡方检验比较不同组之间断裂类型分布的差异，并进行两两比较。结果： 2.50%NaOCl实验组［（26.04±5.74 ）MPa］和5.25%NaOCl实验组［（24.46±3.77） MPa］的粘接强度明显低于未经NaOCl溶液处理的阴性对照组［（48.71±7.77 ）MPa］，P=0.000。与阴性对照组比较，2.50%和5.25%NaOCl实验组粘接强度分别下降了46.5%和50.2%,2.50%和5.25%NaOCl实验组间粘接强度差异无统计学意义（P=0.214）。不同实验组之间断裂类型分布差异均具有统计学意义（χ2=56.324,P=0.000）， 阴性对照组试样断裂类型以混合破坏类型（68.9%）为主，界面破坏类型（24.4%）次之，内聚破坏类型（6.7%）最少,2.50%NaOCl实验组与5.25%NaOCl实验组发生界面破坏类型的比例明显高于阴性对照组(P=0.000)，2.50%NaOCl实验组和5.25%NaOCl实验组间的断裂类型分布差异无统计学意义（P=0.197），且均未发现内聚破坏。结论： NaOCl处理过的牙本质与复合树脂的粘接强度明显降低。

Objective： To evaluate the influence of sodium hypochlorite (NaOCl) solution used during root canal therapy on dentin bond strength. Methods: In the study, 15 freshly extracted human third molars with complete dental crowns, caries and filling-free were selected. The occlusal enamel was removed perpendicular to the long axis of the tooth to expose middle flat surfaces of sound dentin. The occlusal dentin surfaces were then polished using 600-grit silicon papers for 1 min and rinsed with deio-nized water for 1 min. The teeth were randomly divided into three groups according to the treatment received: group A (negative control group), the samples were immersed in deionized water for 20 min; group B, the dentin surfaces were immersed in 2.50% NaOCl solution for 20 min, with the solution being renewed every 5 min; group C, the dentin surfaces were immersed in 5.25% NaOCl solution for 20 min, with the solution being renewed every 5 min. All the treated dentin surfaces were bonded using a self-etching adhesive system (SE bond) with a 5 mm in height resin composite (AP-X). After storage in deionized water at 37 ℃ for 24 h, the adhesive samples were sectioned longitudinally to produce 1.0 mm×1.0 mm stick specimens(n=45) for micro-tensile bond strength testing (MPa). Failure modes (adhesive failure, cohesive failure or mixed failure) at the dentin-resin interface were observed using a stereomicroscope. The micro-tensile bond strength data among the three groups were analyzed by a one-way ANOVA, then the Post-hoc test（LSD）was employed for pairwise comparison. The distribution of failure modes among the groups were analyzed by chi square test. Results:  Significant decreased bond strength values were found for the 2.50% NaOCl-treated group (26.04±5.74) MPa and 5.25% NaOCl-treated group (24.46±3.77) MPa when compared with the strength of negative control group (48.71±7.77) MPa，P=0.000. Compared with the negative control group, themicro-tensile bond strength of the 2.50% NaOCl-treated group and 5.25% NaOCl-treated grouphad dropped by 46.5% and 50.2%. However, there was no significant difference of bond strength between the 2 NaOCl-treated groups （P=0.214）. The distribution of failure modes showed significant difference in all the three groups （2=56.324, P=0.000）. The mixed failure (68.9%) was the most mode of fracture in the negative control group, followed by adhesive failure(24.4%), and the cohesive failure was least（6.7%）. The proportion of adhesive failure mode was higher in NaOCl-treated groups than in negative control group  (P=0.000)． There was no significant difference of the distribution of failure modes between the 2.50% NaOCl-treated group and 5.25% NaOCl-treated group（P=0.197）, and there was no cohesive failure mode detected in the two groups. Conclusion： The micro-tensile bond strength of dentin to composite resin was lower after exposure to NaOCl solution.