Reducing the incompatibility between simplified adhesives and chemically-cured resin cements

Objectives: To determine if the adverse interaction between simplified/acidic etch-and-rinse adhesive (One-Step [OS], Bisco) and chemically-cured resin luting cement [Variolink, Ivoclar Vivadent] can improve adhesive coupling by reducing the dentin permeability with an oxalate desensitizer (Bis-Block [BB], Bisco). Methods: After exposure of dentin on occlusal surfaces of third human molars, bonding was performed with (15s)on either oxalate treated or non-treated demineralized dentin. A resin luting cement was placed in the format of a crown following the light-cured mode (only with the base syringe [LC]) or the chemically-cured 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 (5min) or after a delay of 20min [DP] for both modes of polymerization. Five teeth were assigned for each experimental condition. Teeth were sectioned to obtain sticks with cross-sectional area of 0.8mm2, which were tested following the microtensile bond strength test (BS) soon after the specified periods of polymerization. The BS values of each adhesive were analyzed by three-way repeated measures ANOVA and Tukey's tests (alfa=0.05). Results: The cross-product interactions Use of Bis-Block vs. Mode of activation (p=0.006) and Use of Bis-Block vs. Polymerization period (p=0.00001) were statistically significant. Regardless the period of activation, the BS (mean/standard deviation [MPa]) was significant higher when the BB was employed either in the IM [28/3.3] or DP [31.7/3.8] compared to the non use of BB (IM: 22.2/4.3; DP: 12.3/2.4). The use of BB also improved significantly the BS of LC [31.7/3.7] and CC [28/3.4] compared to the non use of BB (IM: 22.9/4.5; DP: 11.6/2.1). Conclusions: The use of an oxalate desensitizer reduced the incompatibility between light cured resin cements when delayed polymerized and chemically-cured resin luting cements.