Preservation of resin-dentin interfaces treated with benzalkonium chloride adhesive blends.

Reducing collagen degradation within hybrid layers may contribute to the preservation of adhesive interfaces. This study evaluated the stability of resin-dentin interfaces treated with benzalkonium chloride (BAC)-modified adhesive blends and assessed collagen degradation in dentin matrices treated with BAC. The etch-and-rinse adhesive, Adper Single Bond Plus, modified with 0.5% and 1.0% BAC, was evaluated for microtensile bond strength (μTBS) and nanoleakage (NL) after 24 h and 1 yr. Thirty completely demineralized dentin beams from human molars were dipped for 60 s in deionized water (DW; control), or in 0.5% or 1.0% BAC, and then incubated in simulated body fluid (SBF). Collagen degradation was assessed by quantification of the dry mass loss and the amount of hydroxyproline (HYP) released from hydrolyzed specimens after 1 or 4 wk. Although all groups demonstrated a significant increase in NL after 1 yr, adhesive modified with 0.5% BAC showed stable bond strength after 1 yr (9% decrease) relative to the control (44% decrease). Significantly less HYP release and dry mass loss were observed for both 0.5% and 1.0% BAC relative to the control. This in vitro study demonstrates that BAC contributes to the preservation of resin-dentin bonds for up to 1 yr by reducing collagen degradation.