The synergistic effects of SrF_2 nanoparticles, YSZ nanoparticles, and poly-e- L-lysin on physicomechanical, ion release, and antibacterial-cellular behavior of the flowable dental composites

摘要

Resin-based pit-and-fissure sealants (flowable resin composites) were formulated using bisphenol-A-glycer-olatedimethacrylate (Bis-GMA)-triethylene glycol dimethacrylate-(TEGDMA)-diurethanedimethacrylate (UDMA) mixed monomers and multiple fillers, including synthetic strontium fluoride (SrF2) nanoparticles as a fluoride-releasing and antibacterial agent, yttria-stabilized zirconia (YSZ) nanoparticles as an auxiliary filler, and poly-epsilon-L-lysin (epsilon-PL) as an auxiliary antibacterial agent. Based on the physical, mechanical and initial antibacterial properties, the formulated nano-sealant containing 5 wt% SrF2, 5 wt% YSZ and 0.5 wt% epsilon-PL was selected as the optimal specimen and examined for ion release and cytotoxicity. The results showed an average release rate of 0.87 mu g-cm(-2)-day(-1) in the aqueous medium (pH 6.9) and 1.58 mu g-cm(-2)-day(-1) in acidic medium (pH 4.0). The maximum cytotoxicity of 20% toward human bone marrow mesenchymal stem cells (hMSCs) was observed according to the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) cytotoxicity assay and acridine orange staining test. A synergy between SrF2 nanoparticles and epsilon-PL exhibited a better antibacterial activity in terms of colony reduction compared to the other samples. However, the inclusion of SrF(2 )and epsilon-PL caused mechanically weakening of the sealants that was partly compensated by incorporation of YSZ nanoparticles (up to 10 wt%).