Impairment of resin cement application on the bond strength of indirect composite restorations

The aims of this study were to evaluate the effect of immediate and delayed resin cement application on the microtensile bond strength of indirect composite resin restorations and, to evaluate adhesive strategies (for regular resin cement or humidity parameters for self-adhesive resin cement). Forty-five enamel/dentin discs (0.5 mm height and 10 mm of diameter) obtained from bovine teeth were divided into nine groups (n = 5). For regular cement, the variation factors were cementation technique at three levels (immediate cementation, 5 or 30 min after adhesive system application); and type of adhesive system at two levels (three- or two-step). For self-adhesive cement, the dentin moisture was the source of variation at three levels (normal, dry, or wet cementation). The specimens were submitted to microtensile bond strength (μTBS) testing using a universal testing machine. Data were analyzed by ANOVA, Tukey’s test, and linear regression. Regular cement and three-step etch-and-rinse adhesive system showed the highest values of bond strength (25.21 MPa–30 min of delay). Only for this condition, three-step adhesive showed higher bond strength than the two-step adhesive. Nevertheless, the linear regression showed that irrespective of the strategy, the use of the two-step approach when compared with three-step adhesive system decreased μTBS (p本研究旨在评估即刻与延时树脂水门汀（resin cement）涂布对间接复合树脂修复体微拉伸粘结强度（microtensile bond strength, μTBS）的影响，并探究适用于常规树脂水门汀的粘结策略，以及自粘结树脂水门汀的湿度参数。本研究从牛牙制备45块牙釉质/牙本质圆盘（高度0.5 mm，直径10 mm），并将其分为9组，每组样本量n=5。对于常规树脂水门汀，其变量因素包括3个水平的粘结技术（即刻粘结、粘结系统涂布后5 min或30 min进行粘结），以及2个水平的粘结系统类型（三步法与两步法粘结系统）。对于自粘结树脂水门汀，其变量因素为3个水平的牙本质湿度（正常、干燥或湿润粘结）。采用万能试验机对所有试件进行微拉伸粘结强度测试。采用方差分析（ANOVA）、Tukey检验与线性回归对实验数据进行统计分析。常规树脂水门汀联合三步酸蚀冲洗型粘结系统组展现出最高的粘结强度值（25.21 MPa，延时30 min组）。仅在该实验条件下，三步法粘结系统的粘结强度高于两步法粘结系统。然而，线性回归分析显示，无论采用何种粘结策略，与三步法粘结系统相比，使用两步法粘结系统均会降低微拉伸粘结强度（p