Disinfection of endodontic files using silver nanoparticles solution

Objectives: The aim of this study was to evaluate the efficacy of silver nanoparticles (Ag-NPs) solution on disinfection of endodontic files in different exposure time. Methods: Three hundred endodontic files were placed in Brain Heart Infusion broth containing 100 µL suspension of Staphylococcus aureus, Streptococcus mutans, Enterococcus faecalis, Escherichia coli and Candida albicans (106 cel/mL) for 24h each. After contamination, the instruments were immersed in a 47ppm Ag-NPs solution for 5, 10, 15, and 30 min. A spore suspension of Bacillus atrophaeus was added to the Ag-NPs solution and maintained immersed for the same periods of time. Selective media for each microorganism were used for the quantitative analysis of CFU/mL. Results: Silver nanoparticles solution led to a 70.5% reduction in CFU/mL of B. atrophaeus spores. The Ag-NPs solution also showed a reduction in between 77 and 99% of other types of bacteria and 100% yeast elimination. There were statistical significant differences between the control group and all the other experimental groups (p<0.05). Conclusion: The 47ppm Ag-NPs solution was effective in the disinfection process of endodontic files, showing a time-dependent relationship.