The purpose of this study was to evaluate the effects of long-term storage on the microtensile bond strength (µTBS) to dentin of two self-adhesive and three multi-step resin cements. Two self-adhesive cements RelyX U100 (U100) and seT PP (SET), and 3 multi-step resin cements, one using 2-step etch-and-rinse adhesive AllCem (ALC), and two conventional resin cements with self-etching primer Panavia F (PAN) and Multilink (MULT) were used. Human molars were restored (n=5), sectioned and subjected to the μTBS test after 24 h and 6 months. Fractured specimens were examined by stereomicroscope and SEM. The µTBS were analyzed by one-way ANOVA and Tukey test (α=0.05). ANOVA revealed a difference between groups (p<0.0001). All multi-step resin cements ALC, MULT and PAN showed statistically similar bond strength values that were higher than those of the U100 and SET groups. The bond strength value of ALC, MULT and PAN decreases significantly after 6 months. The majority of the failures were adhesive for all the groups. The µTBS produced by the self-adhesive cements were significantly lower than those observed for multi-step luting agents. Regardless of the numbers of steps of resin cements, the storage time reduces µTBS values to dentin only to multi-step luting agents.

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