Influence of dental substrate and adhesive strategy on bond strength of two universal adhesive systems: an in vitro study

The aim of this study is to evaluate the bond strength of two different adhesive systems in bovine teeth, using etch-and-rinse and self-etching technique in enamel and dentin with a bulk fill composite resin. For this purpose, were selected 112 bovine teeth, divided in 8 groups (n=14), being: ECP - enamel conditioned with phosphoric acid; EWA - enamel without prior acid etching; DCP – dentin conditioned with phosphoric acid and DWA – dentin without prior acid etching the groups corresponding to each adhesive tested. The surface treatment was carried out according to the manufacturer's instructions for each group. Three bulk fill composite resin cylinders were fabricated in each tooth, totaling 42 cylinders per group. After 24 hours, the micro-shear bond strength test was performed. The data was analyzed with a Shapiro-Wilk test, followed by analysis of variance and Tukey's post-test. There was a significant difference in the group corresponding to the Single Bond Universal adhesive ECP, obtaining better results. In the intergroup comparison, the two tested products showed no statistical difference between them. The universal adhesives can be used obtained satisfactory results in both techniques. The Single Bond Universal demonstrated a more effective bonding when used acid enamel conditioning on the enamel.