目的:研究根管治疗过程中残留在牙本质表面的环氧树脂类根管封闭剂对牙本质-复合树脂粘接强度的影响,对比不同有机溶剂对其清除的效果.方法:选取新鲜无龋人第三磨牙离体牙25颗,切除冠部釉质,制备牙本质平面试件.试件随机分为5组,每组5颗离体牙.阴性对照组牙本质表面不做处理,不涂根管封闭剂,其他4个实验组试件牙本质表面涂布环氧树脂根管封闭剂AH-Plus 5 min后,采用不同的清除措施:阳性对照组使用干棉球擦拭;乙酸戊酯、丙酮及乙醇有机溶剂实验组,分别用蘸有99％ (体积分数)乙酸戊酯、99. 5％ (体积分数)丙酮及 95％(体积分数)乙醇的棉球擦拭牙本质表面,直至体视显微镜(× 10)下观察无残留AH-Plus,去离子水冲洗3 s.制备1.0 mm × 1.0 mm条状粘接树脂试样(n=45)用于测定微拉伸强度,体视镜下观察断裂类型.制备1.0 mm厚片状试样(n=4)用于扫描电镜下观察粘接界面.采用单因素方差分析比较不同实验组的微拉伸粘接强度,应用卡方检验比较不同组之间断裂类型的差异.结果:五组间粘接强度差异有统计学意义(P<0.001).干棉球组 [(38.69 ±8.60)MPa]、乙醇组[(37.14±12.01)MPa]与阴性对照组[(43.86±7.99)MPa]相比,粘接强度明显降低(P <0.05).干棉球组与乙醇组粘接强度差异无统计学意义(P=0. 426).丙酮组、乙酸戊酯组、阴性对照组三者粘接强度差异无统计学意义(P >0.05),丙酮、乙酸戊酯清洁牙本质表面后粘接强度分别达到(45. 94 ± 10.37) MPa、(43.99 ±7.01) MPa.乙醇组粘接强度明显低于丙酮组和乙酸戊酯组(P <0. 05).扫描电镜下观察可见:干棉球组及乙醇组树脂突短小而稀疏,且在乙醇组的粘接界面可以看到残留的根管封闭剂;阴性对照组、乙酸戊酯组及丙酮组树脂突均匀致密.不同组之间断裂类型分布差异没有统计学意义(P=0.086).结论:环氧树脂类根管封闭剂残留使牙本质树脂粘接强度下降.丙酮与乙酸戊酯对牙本质表面残留的AH-Plus的清除效果较好,优于乙醇及干棉球.%Objective: To evaluate the influence of an epoxy resin-based sealer on the bond strength of adhesive resins to dentin and the cleaning efficacy of different solvents in removing sealer residues. Methods: The occlusal enamel of 25 freshly extracted human third molars without caries were removed to expose flat surfaces of dentin. The teeth were randomly divided into five groups according to the treatment received: For negative control group, the dentin surfaces were not contaminated with AH-Plus; For the other 4 experimental groups, the samples were contaminated with AH-Plus for 5 min and different measures were taken:For positive control group, the sealer were wiped with dry cotton pellets; For solvents experimental groups: cotton pellets saturated with 95％ (volume fraction) ethanol, 99. 5％ (volume fraction) acetone or 99％ (volume fraction) amyl acetate were used to wipe the sealer until the surface appeared clean when viewed through a stereomicroscope under × 10 magnification,then rinsed with deionized water for 3 s. After sealer removal, a self-etching adhesive system was applied on the surfaces with resin composite. The samples were sectioned into 1. 0 mm × 1. 0 mm stick specimens (n =45) for microtensile test. Failure modes at the dentin-resin interface were observed using a stereomicroscope. The samples were sectioned into 1.0 mm piece specimens (n =4) for scanning electron microscope observation. The microtensile bond strength data were analyzed by one-way ANOVA. Chi-square test were used to analyse the failure modes between the groups. Results: There was significant difference among the five groups (P<0.001). For dry cotton pellet group (38.69 ±8.60) MPa and the ethanol group (37.14 ± 12. 01) MPa, the microtensile bond strength significantly declined when compared with negative control group (43.86 ±7.99) MPa (P <0. 05 ). No significant difference of bond strength was found between the dry cotton pellet group and the ethanol group (P =0.426). There was no statistical significant difference among acetone group, amyl acetate group and negative control group (P>0. 05). The bond strength of acetone group and amyl acetate group were (45.94 ± 10. 37) MPa and (43. 99 ±7.01) MPa, respectively. The ethanol group exhibited lower bond strength than that of acetone group and amyl acetate group (P <0. 05 ). Scanning electronic microscope observation revealed that in dry cotton pellet group and ethanol group, the resin tags were short and loose. Moreover, sealer residues were identified in the interface in the ethanol group samples,while the resin tags in the acetone and amyl acetate group were as dense and uniform as in negative control group. The distribution of failure modes showed no significant difference in the five groups (P =0. 086). Conclusion: The microtensile bond strength of dentin to composite resin was lower after exposure to sealer. Compared with ethanol and dry cotton pellets, the cleaning effect of acetone and amyl acetate on sealer-contaminated dentin surface were better.
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