Reducing the Incompatibility Between Two-step Adhesives and Resin Composite Luting Cements

Purpose: To determine whether the adverse interaction between a two-step/acidic etch-and-rinse adhesive (One-Step Plus [OS], Bisco) and chemically cured resin luting cement [Variolink II, Ivoclar Vivadent] can improve adhesive coupling by reducing the dentin permeability with an oxalate desensitizer (BisBlock, Bisco). Materials and Methods: After exposing dentin on the occlusal surfaces of human third molars, bonding was performed on either oxalate treated (BB) or nontreated (NB) demineralized dentin. A resin luting cement was placed in the format of a crown following the light-curing mode (only with the base syringe [LC]) or the chemically curing mode (mixture of base and catalyst syringes [CC]). The activation of the LC or CC cements was either immediately [IM], meaning soon after the placement of LC and the initial set of CC cement (5 min), or after a delay of 20 min [DP] for both modes of polymerization. Five teeth were assigned to each experimental condition. Teeth were sectioned to obtain sticks with a cross-sectional area of 0.95 mm2, which were tested using the microtensile bond strength test soon after the specified periods of polymerization. The bond strength values of each adhesive were analyzed by three-way repeated measures ANOVA and Tukey's tests (α = 0.05). Fractographic analysis of the specimens was performed using SEM. Results: The delayed polymerization (for both LC and CC cements) produced low bond strength values compared to IM activation. When the BB was employed, the bond strength values of the CC cement was approximately doubled, while the BB did not affect the bond strength of the LC cement. Bond strength values of LC cements were higher than CC. The use of BB significantly improved the bond strength of CC cement only. The morphological observations confirmed the bond strength results. A myriad of voids could be detected in the luting cement side when BB was not applied, except for the immediately light-cured group. Conclusion: The use of an oxalate desensitizer (BisBlock) reduced the incompatibility between a two-step etch-andrinse adhesive and chemically cured resin cements and light-cured systems in the delayed polymerization mode. Keywords: etch-and-rinse adhesive, chemically cured, delayed polymerization, resin luting cement, oxalate desensitizer, microtensile bond strength