Antibacterial activity improvement of dental glass-ceramic by incorporation of AgVO3 nanoparticles.

Abstract

This study aimed to investigate the role of the incorporation of an antibacterial nanoceramic (AgVO3) on the properties of a restorative dental glass-ceramic. A commercially available restorative glass-ceramic, commonly designated as porcelain (IPS d.SIGN) was functionalized with an antibacterial agent (nanostructured β-AgVO3), synthesized by a hydrothermal route. Both functionalized and pristine samples were processed according to the manufacturer's instructions. All samples were characterized by X-ray diffraction, Rietveld refinement, particle size distribution, Scanning Electron Microscopy, chemical solubility, and Inductively Coupled Plasma Spectroscopy. Their antibacterial potential (Mueller-Hinton test) was analyzed against gram-positive (Staphylococcus aureus) and gram-negative bacteria (Escherichia coli). The commercial glass-ceramic showed leucite (KAlSi2O6) as the only detectable crystalline phase, and, for both strains, no antibacterial activity could be detected in the Mueller-Hinton agar plates test. A monophasic, needle-shaped, and nanometric β-AgVO3 powder was successfully synthesized by a simple hydrothermal route. After thermal treatment, glass-ceramic samples containing different percentages of β-AgVO3 showed a second crystalline phase of microline [K0.95(AlSi3O8)]. For modified samples, inhibition halos were easily visible on the Mueller-Hinton test, which ranged from 11.1±0.5mm to 16.6±0.5mm and 12.7±0.3mm to 15.5±0.3mm in the S. aureus and E.coli cultures, respectively, showing that the halos formed were dose-dependent. Also, increasing the percentage of β-AgVO3 promoted a significant increase in chemical solubility, from 72µg/cm2 (samples with 1wt% of β-AgVO3) to 136µg/cm2 (samples with 2wt% of β-AgVO3), which was associated with the silver and vanadium ions released from the glass matrix. Our in vitro results indicate that IPS d.SIGN, as most of the dental glass-ceramics, do not exhibit antibacterial activity per se. Nonetheless, in this concept test, we demonstrated that it is possible to modify dental veneering materials giving them antibacterial properties by adding at least 2wt% of β-AgVO3, a nanomaterial easily synthesized by a simple route.