The objective was to compare bond strengths of adhesives with/without thermocycling and to analyze the micromorphology of resindentin interfaces. Flat dentin surfaces were prepared and divided into eight groups to bond with four etch-and-rinse adhesives (Optibond FL, Adper Scotchbond Multi-Purpose, Optibond Solo Plus, and Single Bond 2) and four self-etch adhesives (Clearfil SE Bond, Adper SE Plus, Clearfil S 3 Bond and Adper Easy Bond). Specimens were further divided into two subgroups subjected for with/ without thermocycling and then subjected to both micro-tensile test and resin-dentin interface evaluation. The results revealed that there were significant differences in bond strength between the groups with and without thermocycling for all etch-and-rinse groups and for the Adper Easy Bond self-etch group (p<0.01). Clearfil SE Bond demonstrated highly durable bond strengths. Furthermore, more silver ion uptake was observed at the resin-dentin interfaces for all etch-and-rinse adhesives and Adper SE Plus and Adper Easy Bond after thermocycling.

The objectives of this study were to evaluate the bond strength and the nanoleakage of resin composite restorations at the resin/dentine interface.Flat occlusal dentine surfaces were prepared from extracted premolars, etched with phosphoric acid and treated with either 2% chlorhexidine digluconate (CHX) orµM100rosmarinic acid solution (RMA) or were not treated. The specimens were then restored with either three-step (OptiBond ® FL) or two-step (OptiBond ® Solo Plus TM ) etch-and-rinse adhesives and a resin composite. The restored teeth were prepared as hourglass specimens and further divided according to the storage media (pure mineral oil or artificial saliva) and storage time (24 hours, 3 months, 6 months, and 1 year). The storage specimens were subjected to a micro-tensile bond strength test and a nanoleakage observation.The bond strength to dentine of both adhesives without dentine surface treatment decreased after storage in artificial saliva for 3 months to 1 year (p<0.05) but did not decrease after storage in pure mineral oil. Dentine surface treatment with either CHX or RMA, under either of the adhesives, was able to postpone the degradation of the bond strength by 3 months (p<0.05). Nanoleakage within the resin-dentine interface bonded without dentine surface treatment increased over time when it was stored in artificial saliva but not in pure mineral oil. Dentine surface treatment with either CHX or RMA prevented nanoleakage only up to 3 months of storage. These findings suggest that effectiveness of MMP-inhibitors in preserving the integrity of the resin-dentine bond is time dependent.