BOND STRENGTH DURABILITY OF SELF-ETCHING ADHESIVES AND RESIN CEMENTS TO DENTIN

OBJECTIVES: To evaluate the microtensile bond strength (μTBS) of one- (Xeno III, Dentsply) and two-step (Tyrian-One Step Plus, Bisco) self-etching adhesive systems bonded to dentin and cemented to chemically cured (C&B Metabond) or light-cured paste of a dual-cure resin cement (Variolink II, Ivoclar) within a short (24 h) and long period of evaluation (90 days). MATERIAL AND METHODS: Forty recently extracted human molars had their roots removed and their occlusal dentin exposed and ground wet with 600-grit SiC paper. After application of one of the adhesives, the resin cement was applied to the bonded surface and a composite resin block was incrementally built up to a height of 5 mm (n=10). The restored teeth were stored in distilled water at 37°C for 7 days. The teeth were then cut along two axes (x and y), producing beam-shaped specimens with 0.8 mm(2) cross-sectional area, which were subjected to μTBS testing at a crosshead speed of 0.05 mm/min and stressed to failure after 24 h or 90 days of storage in water. The μTBS data in MPa were subjected to three-way analysis of variance and Tukey's test (α= 0.05). RESULTS: The interaction effect for all three factors was statistically significant (three-way ANOVA, p<0.001). All eight experimental means (MPa) were compared by the Tukey's test (p<0.05) and the following results were obtained: Tyrian-One Step Plus/C&B/24 h (22.4±7.3); Tyrian-One Step Plus/Variolink II/24 h (39.4±11.6); Xeno III/C&B/24 h (40.3±12.9); Xeno III/Variolink II/24 h (25.8±10.5); Tyrian-One Step Plus/C&B/90 d (22.1±12.8) Tyrian-One Step Plus/VariolinkII/90 d (24.2±14.2); Xeno III/C&B/90 d (27.0±13.5); Xeno III/Variolink II/ 90 d (33.0±8.9). CONCLUSIONS: Xeno III/Variolink II was the luting agent/adhesive combination that provided the most promising bond strength after 90 days of storage in water.