Effects of a Mouthrinse Containing Silver Nanoparticles on Polymicrobial Oral Biofilms

Purpose: To investigate the antimicrobial effects of a mouthrinse containing silver nanoparticles (AgNP) on polymicrobial biofilms in vitro. Materials and Methods: Polymicrobial biofilms were grown on glass cover slips following the method of Exterkate. Saliva collected from a healthy human was added to McBain medium (including 0.2% sucrose) to achieve a 50-fold dilution. Glass coverslips were attached to the lid of a 24-well culture plate and suspended in the medium of each well. After 24 h of cultivating, coverslips with biofilms were immersed in each of four treatment solutions or sterile deionized water for 5 min. The control and four treatment groups were as follows: 1) control: sterile deionized water; 2) nanosilver (NS): mouthrinse containing AgNP; 3) 0.05C: 0.05% chlorhexidine gluconate; 4) 0.2C: 0.2% chlorhexidine gluconate; 5) Xyl: 25% xylitol. The biofilms were further regrown for 48 h. After removing the biofilms ultrasonically, they were cultured on blood agar, viable cells were counted, and the amount of lactic acid in the biofilms was analysed using a colorimetric assay. Results: Mouthrinse containing AgNP suppressed viable cells in the biofilm to the same degree or more than with chlor-hexidine gluconate. Amounts of lactic acid after 72 h cultivation of biofilms treated with 0.2C and NS showed consistently low values.Conclusion: The mouthrinse containing AgNP suppressed viable cells in polymicrobial biofilms to the same level as 0.2% chlorhexidine or higher.