Evaluation of Bond Strength of Indirect Restorations to Bleached Enamel

Objectives: The aim of this study was determined the shear bond strength(SBS) of composite resin and ceramic to bleached enamel 1 day/2weeks after using different adhesive resin luting cements. . Methods: 84 flat enamel surfaces were prepared from freshly extracted non-carious human incisors using low speed diamond saw. Specimens were assigned to a control group and two experimental bleaching groups accoding to the treatment 1 day or 2 weeks after bleaching with %30 carbamide peroxide (Zaris White&Brite, %30, 3M ESPE). Each group were divided into four subgroups; G1: Ceramic blocks (CB, IPS Empress II, Ivoclar-Vivadent) with light-cured resin (LC, Rely X Veneer, 3M, ESPE) luting cement. G2: Composite resin blocks (CRB, Filtek Supreme XT, 3M ESPE) with LC. G3: CB with dual-cured resin (DC, Rely X ARC, 3M, ESPE) luting cement, G4:CRB with DC. Before bonding procedures, teeth were etched and bonding agents were applied according to manufacturer's recommendations, 2mm thick composite blocks and ceramic blocks were etched(HF, 3M, ESPE) and silaneted with porcelain silan (Rely X ceramic primer, 3M ESPE). The specimens were stored in water at 37 degrees C for 1 day/2 weeks. Specimens were thermocycled 1000 times and SBS were determined using a universal testing machine. Results: The statistical analysis was done by using three-way analysis of variance(ANOVA) and Chi-Square tests at a significance level of p›0.05 The samples that were bonded one day after bleaching demonstrated significantly lower shear bond strengths. There were no significantly statistical difference found among all the groups but ceramic groups especially luted with Rely X Veneer(G1) showed better results. Conclusion: Bleaching significantly decreased bond strength at day one but after two weeks, bleaching showed no significant effect. The use of adhesive luting system may provide adequate bond strengths for composite and ceramic indirect restorations after bleaching process.