Development of experimental HEMA-free three-step adhesive system

Objective luate the influence of Bis-EMA 30 on the resin-to-dentin microtensile bond strength (μTBS) and structural reliability of the experimental three-step etch-and-rinse adhesive systems. s xperimental primers containing different dimethacrylate monomer concentrations (0, 10, 20, 40, 60 wt% of the Bis-EMA 30, P0.P60) added to acid monomer and solvents (ethanol/water), and a resin bond (Bis-GMA/TEGDMA, 50/50 wt%) were formulated. The adhesive system Scotchbond™ MultiPurpose (SBMP, 3M ESPE) was tested as commercial reference. Sixty bovine incisors were randomly separated into six groups, and their superficial coronal dentin was exposed. After acid etching and rinsing, the excess water was removed from the surface with absorbent paper. Each experimental primer was actively applied (30 s), followed by a mild air stream (10 s). The experimental adhesive resin was applied and light activated for 20 s. Resin composite restorations were incrementally built up. The restored teeth were stored in distilled water at 37 °C for 24 h, and then sectioned to obtain sticks with a cross-sectional area of approximately 0.5 mm2, after which 24 specimens per group were subjected to the μTBS test. Data (MPa) were analyzed by One-way ANOVA, Tukey test (α = 0.05) and Weibull analysis. s 0 group showed μTBS means similar to those of the control (SBMP), whereas both had statistically higher values when compared with the other groups (p < 0.001). Moreover, P40 showed higher structural reliability, represented by the high Weibull modulus and characteristic strength values. The lowest μTBS was observed in the P0, P10 and P20 groups, which also had low structural reliability. icance A 30 is a promising monomer to be considered as a substitute for HEMA in adhesive system compositions.