This study evaluated the effects of water exposure on the in vitro microtensile bond strength (pTBS) of etch-and-rinse and self-etching adhesives to human dentin over a 1-year storage period. Five adhesive systems used were as follows: a one-step self-etching adhesive (One-up Bond F-OB), two two-step self-etching primers (Clearfill SE Bond-SE and Clearfil Protect Bond-CP), and two etch-and-rinse adhesives (Single Bond-SB and Prime&Bond NTPB). Dentin surfaces were bonded, restored, and assigned to four subgroups, according to the degree of water exposure: 24 h of peripheral water exposure (24 h-PE) (having circumferential enamel); and 1 year of peripheral exposure (1 yr-PE), direct exposure (1 yr-DE) (dentin directly water-exposed), or directly exposed to oil only (no water exposure) (1 yr-DOE). A composite-enamel bond adjacent to the restoration is determined if the water exposure was peripheral or direct. After storage periods, specimens were serially sectioned, trimmed to an hourglass shape with a cross-sectional area of I turn 2 at the interface, and tested in tension. Results were analyzed by two-way ANOVA and Tukey test (a = 0.05). No difference was found between 24 h-PE and I yr-PE for OB, CP, SB, and PB. However, pTBS values significantly dropped after 1 yr-DE for SE, CP, SB, and PB. A decreased pTBS was seen in SE after 1 yrPE, but no differences existed between I yr-PE and 1 yr-DE. Similar or increased pTBS values were noted in 1 yr-DOE for all adhesives. Water-storage for I year significantly decreased pTBS for all adhesives. However, except for SE, the presence of a peripheral composite-enamel bond seemed to reduce the degradation rate in resin-dentin interfaces for all materials. (c) 2007 Wiley Periodicals, Inc.85B1101
