Pre-etching dentin effects on morphology and bond strength of self-etching adhesives

A new one versatile all-in-one self-etch adhesive system has been developed to combine total-etch and self-etch features. Objective : to evaluate the tensile bond strength (µTBS) and interface bond morphology of self-etching adhesives on phosphoric acid pre-etched dentin surface. Methods : Ten extracted human molars were ground to obtain a flat dentin surfaces and polished with 600-grit SiC paper. The specimens were randomly divided into five groups: (G1) Scothbond Universal Adhesive – SU (3M ESPE); (G2) pre-etched SU; (G3) Adper Easy Bond – EB (3M ESPE); (G4) pre-etched EB; and (G5) Adper Single Bond Plus – SB (3M-ESPE). Pre-etching specimens were conditioned with 35% phosphoric acid (PA) for 15s. All adhesives were applied according to manufacturer’s instructions and composite resin crowns were incrementally built up. After 24h, 0.8-mm² beams were obtained and tested to µTBS. In order to observe dentin-adhesive interface, selected beams from each group were stained with 0.1% Rodhamine B for 1h and analyzed using Confocal Laser Scanning Microscopy (CLSM). Data were analyzed using ANOVA and Fisher’s PLSD test (α=0.05). Results : No statistical difference was observed among the groups (P>0.05): G1=46.96(18.7)MPa; G2=44.14(13.7)MPa; G3=42.72(13.8)MPa; G4=41.59 (13.6)MPa; and, G5=40.74 (12.0)MPa. Conclusions : Pre-etching dentin using PA did not affect µTBS values of one-step self-etching adhesives. The resin-dentin bond interface thickness of self-etching adhesives increased on pre-etched dentin approach.