Antibacterial activity of silver nanoparticle (AgNP) confined mesoporous structured bioactive powder against Enterococcus faecalis infecting root canal systems

Abstract

Many clinical cases show that the failure of root-canal treatment is primarily attributable to remnants of bacteria in root canal systems, especially Enterococcus faecalis (E. faecalis).In this study, silver nanoparticle (AgNP) confined mesoporous structured bioactive powder (M-BP-Ag) was prepared by the evaporation-induced self-assembly (EISA) method and evaluated for antibacterial activity against E. faecalis. The composition of the M-BP-Ag belongs to the SiO2-CaO-P2O5 system. The M-BP-Ag was obtained with the composition ratios of Si, Ca, P, and Ag in mole% being (80-X), 15, 5, and X, where X = 0, 1, 5, or 10, respectively. X-ray diffraction (XRD), gas adsorption and desorption analyzer, and transmission electron microscopy (TEM) were used to characterize these M-BP-Ag.The antibacterial activity of the test samples against E. faecalis was verified by the time-killing curve test and the colony-forming capacity assay. The samples' antibacterial activities depended on the confined AgNP position. From bacterial morphology observation, we also speculated the antibacterial mechanism of the M-BP-Ag test samples in this study.