Effects of a peripheral enamel bond on the long‐term effectiveness of dentin bonding agents exposed to water in vitro

This study evaluated the effects of water exposure on the in vitro microtensile bond strength (μTBS) 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 (Clearfil SE Bond‐SE and Clearfil Protect Bond‐CP), and two etch‐and‐rinse adhesives (Single Bond‐SB and Prime&Bond NT‐PB). 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 1 mm 2 at the interface, and tested in tension. Results were analyzed by two‐way ANOVA and Tukey test ( α = 0.05). No difference was found between 24 h‐PE and 1 yr‐PE for OB, CP, SB, and PB. However, μTBS values significantly dropped after 1 yr‐DE for SE, CP, SB, and PB. A decreased μTBS was seen in SE after 1 yr‐PE, but no differences existed between 1 yr‐PE and 1 yr‐DE. Similar or increased μTBS values were noted in 1 yr‐DOE for all adhesives. Water‐storage for 1 year significantly decreased μTBS 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. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008