Effect of water storage on bond strength of self-etching adhesives to dentin

The objective of this study was to evaluate the bond strength of self-etching adhesive systems one week and one year after storage in water. Fragments from the buccal surfaces of 45 bovine teeth were prepared (12 mm in length x 5 mm in width x 1.0 mm in thickness). Dentin surfaces were wet-abraded with 600-grit SiC paper to create a standardized smear layer. Samples were randomly assigned to 18 experimental groups (n=5), according to nine adhesive systems tested (Single Bond; Adper Prompt L-Pop; iBond; One-Up Bond F; Xeno III; Clearfil SE Bond; Optibond Solo Plus SE; Tyrian SPE/One-Step Plus; and UniFil Bond) and two water-storage times (one week and one year). Adhesives were applied according to the manufacturers' instructions. Z250 composite was applied into the molds to fill up the internal diameter volume of a Tygon tubing mold (1.0 mm high/0.7 mm internal diameter). Micro-shear bond strengths were determined using an apparatus attached to an Instron Universal Testing Machine (0.5 mm/min). Data were statistically analyzed using a two-way analysis of variance (ANOVA) and the Tukey's test (5%). One year after water storage the dentin bond strength of all adhesive systems reduced significantly, except for One-Up Bond F. Water-storage time decreased the bond strength for most dentin bonding agents tested.