Antibacterial efficacy of silver nanoparticles, sodium hypochlorite, chlorhexidine, and hypochlorous acid on dentinal surfaces infected with Enterococcus faecalis.

The purpose of this study was to evaluate the antibacterial effect of silver nanoparticles (AgNPs) against Enterococcus faecalis and compare it with different irrigation solutions. This study was performed using 64 dentin blocks. E. faecalis suspension was dispensed to each sample and incubated under anaerobic conditions at 37°C throughout 21 days. After the inoculation period, the following solutions were added to each group and kept for 5 min: Group 1, 5.25% sodium hypochlorite (NaOCl); Group 2, 2.5% NaOCl; Group 3, 1% NaOCl; Group 4, 2% chlorhexidine (CHX); Group 5, 200 ppm hypochlorous acid (HOCl); and Group 6, AgNPs. The samples of positive control were treated with sterile saline. Biofilm viability assay was performed using the LIVE/DEAD BacLight Bacterial Viability Kit. Samples were examined using confocal laser scanning microscopy, respectively. There was no significant difference between the 5.25% NaOCl, 2.5% NaOCl, and 1%NaOCl groups (p > .05). However, these groups showed statistically higher antibacterial activity than the 2% CHX, 200 ppm HOCl, and AgNP groups. Also, 2% CHX showed greater percentage of dead cells compared with the AgNP and HOCl groups. While AgNPs group showed lower dead cell rate than all NaOCl groups and 2% CHX, it caused higher dead cells than 200 ppm HOCl group. The 200 ppm HOCl group showed the lowest percentage of dead cells (p < .05) Although the antibacterial effect of AgNPs is not as high as NaOCl and CHX, it has considerable bactericidal activity against E. faecalis and can be improved by further studies. RESEARCH HIGHLIGHTS: New antimicrobial approaches for root canal irrigation. Antimicrobial effect of silver nanoparticles against E. faecalis. Elimination of the biofilm layer for the success of endodontic treatment.

Comparative evaluation of the antifungal efficacy of sodium hypochlorite, chlorhexidine, and silver nanoparticles against Candida albicans.

Candida albicans is a microorganism that causes root canal infections. However, it cannot be eliminated with conventional irrigation solutions. Recently, silver nanoparticles (AgNPs) have become popular for their superior antimicrobial effects. The purpose of this study was to evaluate the antifungal effect of AgNPs to C. albicans comparing with 5.25% sodium hypochlorite (NaOCl) and 2% chlorhexidine (CHX). Silver nanoparticles were synthesized by chemical reduction method. Minimum inhibitory concentration and minimum fungicidal concentration of AgNPs against C. albicans strain were determined according to microdilution method reported by Clinical Laboratory Standards Institute. C. albicans biofilm layer was formed on the dentin blocks for 10 days. The biofilm structure was observed by scanning electron microscopy. Statistical analysis was performed with one way analysis of variance analysis and group comparisons were performed with Tukey test. AgNPs showed the highest antifungal effect among the groups. 5.25% NaOCl showed the lowest antifungal effect among the groups. While the 2% CHX solution had a statistically lower antifungal effect than AgNPs, it was found to have a higher effect than NaOCl (p < .016). Nanoparticles present a wide research field as an alternative irrigation solution in root canal treatment. The antifungal effect of AgNPs against C. albicans was confirmed in this study. Further in vivo studies should evaluate the conditions of use and long-term prognosis of AgNPs.

Silver nanoparticles in endodontics: recent developments and applications.

The elimination of endodontic biofilms and the maintenance of a leak-proof canal filling are key aspects of successful root canal treatment. Several materials have been introduced to treat endodontic disease, although treatment success is limited by the features of the biomaterials used. Silver nanoparticles (AgNPs) have been increasingly considered in dental applications, especially endodontics, due to their high antimicrobial activity. For the present study, an electronic search was conducted using MEDLINE (PubMed), the Cochrane Central Register of Controlled Trials (CENTRAL), Google Scholar, and EMBASE. This review provides insights into the unique characteristics of AgNPs, including their chemical, physical, and antimicrobial properties; limitations; and potential uses. Various studies involving different application methods of AgNPs were carefully examined. Based on previous clinical studies, the synthesis, means of obtaining, usage conditions, and potential cytotoxicity of AgNPs were evaluated. The findings indicate that AgNPs are effective antimicrobial agents for the elimination of endodontic biofilms.