Bond strength of self-adhesive resin cements to deep dentin

Introduction and objective: Self-adhesive resin cements are applied in only one clinical step whose technique is considered less sensitive and of easy handling. However, there is some concern relating to a reliable and effective bonding to tooth structure, particularly when dentin is involved. The aim of this study was to evaluate microtensile bond strength of self-adhesive resin cements to deep dentin as well as to discuss some concepts involving these materials. Material and methods: Twenty-eight freshly extracted third molars were used. Their crowns were sectioned using a diamond disc (Isomet) to obtain occlusal deep dentin flat surfaces. The teeth were randomly assigned to four groups (n = 7): RelyX ARC/3M ESPE conventional resin cement (Group 1), and three self-adhesive resin cements – RelyX U100/3M ESPE (Group 2), Set/SDI (Group 3) and Maxcem/Kerr (Group 4). The products were applied according to the manufacturer’s instructions. Tetric EvoCeram (Ivoclar Vivadent) blocks were used to simulate indirect restorations that were cemented onto the dentin surfaces. These blocks were sandblasted with oxide aluminum before adhesive procedures. The samples were stored in distilled water at 37±2°C for one week. Following, the samples were prepared for microtensile bond strength tests, which were performed at a crosshead speed of 1.0 mm/min until failure. Tensile bond strength data were calculated and the results were statistically analyzed by two-way ANOVA and Tukey test (p < 0.05). Results: The means (SD) (in MPa) were – Group 1: 14.7a(5.7); Group 2: 7.5b (2.3); Group 3: 5.6b (2.1); and Group 4: 4.7b(1.4). ANOVA showed significant differences and Tukey test identified differences among groups. Group 1 showed the highest bond strength mean. Bond strength mean of the other self-adhesive resin cements to dentin did not show statistical difference among them. Conclusion:Self-adhesive resin cements showed lower bond strength to dentin than RelyX ARC conventional resin cement. The highest bond strength mean of RelyX ARC is related to its mechanism of action. However, the mechanism of action involved in self-adhesive resin cements seems to be effective for clinical use if a proper prosthetic dental preparation is observed.