Effect of HEMA Phosphate as an Alternative to Phosphoric Acid for Dentin Treatment Prior to Hybridization with Etch-and-Rinse Adhesive Systems.

PURPOSE To evaluate the effect of dentin treatment using HEMA phosphate (HEMA-P) on the microtensile bond strength (μTBS) and nanoleakage of an etch-and-rinse adhesive system. MATERIALS AND METHODS The occlusal surfaces of human molars were wet ground until superficial dentin was exposed. The specimens were then assigned to two groups according to dentin treatment: PA: 37% H₃PO₄ for 15 s; or HP: HEMA-P for 15 s. Adper Single Bond 2 was applied to the treated dentin surfaces and resin composite buildups were incrementally constructed over them. After 24-h storage in artificial saliva at 37°C, the bonded teeth were cut into resin-dentin sticks with a cross-sectional area of 1 mm², which were submitted to μTBS testing immediately or after 3 months of storage in artificial saliva at 37°C. Nanoleakage was assessed using SEM/EDS, and the interaction between dentin and H₃PO₄ or HEMA-P was evaluated by combining micro-Raman and FT-IR spectroscopy. The data were analyzed using two-way ANOVA and Tukey's HSD post-hoc test (α = 0.05). RESULTS HP presented significantly higher μTBS than PA at both times (p < 0.05). Both treatments maintained μTBS stability after 3 months of artificial saliva storage (p > 0.005). At both times, PA presented higher nanoleakage than HP (p < 0.05). CONCLUSIONS Both dentin treatments maintained μTBS stability after 3 months of artificial saliva storage. The use of HEMA-P was associated with less nanoleakage than was traditional phosphoric-acid etching.