Mechanical and microbiological properties and drug release modeling of an etch-and-rinse adhesive containing copper nanoparticles

Objectives To evaluate the effect of addition of copper nanoparticles (CN) at different concentrations into a two-step etch-and-rinse (2-ER) adhesive on antimicrobial activity (AMA), copper release (CR), ultimate tensile strength (UTS), degree of conversion (DC), water sorption (WS), solubility (SO), as well as the immediate (IM) and 1-year resin–dentin bond strength (μTBS) and nanoleakage (NL). Methods Seven adhesives were formulated according to the addition of CN (0, 0.0075, 0.015, 0.06, 0.1, 0.5 and 1 wt%) in adhesive. The AMA was evaluated against Streptococcus mutans using agar diffusion assay. For CR, WS and SO, specimens were constructed and tested for 28 days. For UTS, specimens were tested after 24 h and 28 days. For DC, specimens were constructed and tested after 24 h by FTIR. After enamel removal, the ER was applied to dentin. After composite resin build-ups, specimens were sectioned to obtain resin–dentin sticks. For μTBS and NL, specimens were tested after 24 h and 1-year periods. All data were submitted to statistical analysis (α = 0.05). Results The addition of CN provided AMA to the adhesives at all concentrations. Higher CR was observed in adhesives with higher concentration of CN. UTS, DC, WS and SO were not influenced. For μTBS an increase was observed in 0.1 and 0.5% copper group. For NL, a significant decrease was observed in all groups in comparison with control group. After 1-year, no significant reductions of μTBS and no significant increases of NL were observed for copper containing adhesives compared to the control group. Significance The addition of CN in concentrations up to 1 wt% in the 2-ER adhesive may be an alternative to provide AMA and preserve the bonding to dentin, without reducing adhesives’ mechanical properties evaluated.