Comparison of antimicrobial efficacy of calcium hydroxide loaded with nanoparticles of graphene and quercetin as intracanal medicament using two different vehicles against Enterococcus faecalis: a CLSM study

Abstract

Calcium hydroxide has been widely used in endodontics as an intracanal medicament due to its effective antimicrobial activity. Unfortunately, it does not destroy microbiota present in the dentinal tubules. Nanoparticle-loaded Ca(OH) 2 has proven to enter the tubules and exhibit excellent antibacterial efficacy against various bacterial pathogens. To compare the antimicrobial efficacy of Ca(OH) 2, loaded with Graphene(GNP) and Quercetin nanoparticles (QNP) as intracanal medicaments, using two different vehicles—propylene glycol(PG) and distilled water (DW)—against E. faecalis , using Confocal Laser Scanning Microscopy. Sixty decoronated single-rooted teeth were instrumented using 2.5% NaOCl, EDTA, and saline. The canals were inoculated with E. faecalis (ATCC 29212) for 7 days. Graphene and quercetin nanoparticles incorporated into Ca(OH) 2 with propylene glycol and distilled water were placed in the canals, which were then sealed and stored for 14 days. Specimens were examined under confocal laser scanning microscopy. Live/dead bacterial ratios were analyzed using ImageJ and SPSS (version 20.0). The assessment of the total number of live and dead bacteria, and the ratio of dead to live bacteria between all the experimental groups, was done using one-way ANOVA. To assess the significance of differences between pairs of group means, post hoc Tukey's Honest Significant Difference (HSD) test was used. Degree of significance was maintained at 5%. The significantly higher dead: live ratio was seen in Ca (OH) 2  + QNP + DW group in the apical 3rd (3.31 ± 2.1.), followed by the middle third (2.42 ± 1.6) when compared to plain Ca(OH) 2 . In the coronal third, Ca(OH) 2  + QNP + PG showed the highest dead-to-live ratio (2.11 ± 0.75). Ca(OH) 2, loaded with Graphene and Quercetin nanoparticles, has enhanced antibacterial efficacy against E. faecalis when compared to plain Ca(OH) 2 . Though propylene glycol and distilled water are excellent vehicles for delivering Ca(OH) 2 into the canal system, distilled water is a better vehicle in the apical part of the canal than propylene glycol.