Comparative Evaluation of Bactericidal Effect of Silver Nanoparticle in Combination with Nd-YAG Laser against Enterococcus faecalis: An In Vitro Study

Abstract

To evaluate the bactericidal effect of silver nanoparticles and silver nanoparticles in combination with Nd-YAG laser against Enterococcus faecalis. A solution containing 100 μg of silver nanoparticles in 1 mL was prepared by adding 5 mL of 10-4 M solution of AgNO3 with 5 mL of 0.1 M sodium tricitrate. Synthesized silver nanoparticles were characterized using UV-visible spectrophotometer for optical studies and the transmission electron microscopic analysis for determining the size and shape of the nanoparticles. Groups are as follows: group I-silver nanoparticles against E. faecalis, group II-silver nanoparticles in combination with Nd-YAG laser against E. faecalis, group III-control, E. faecalis bacterial culture alone. Optical density was measured periodically at half an hour interval in spectrophotometer in a 96 well plate and statistically analyzed using one-way ANOVA. The optical density and turbidity of groups I and II began to decrease in 2 hours in comparison with the control. There was a significant difference in mean optical density among the three groups after 1½ hours onward. The study also demonstrated the minimal bactericidal concentration (MBC) as 100 μg/mL of Ag nanoparticles with a size of 15 nm were effective against E. faecalis. The study concluded that silver nanoparticles individually and in conjunction with Nd:YAG laser irradiation would be an effective protocol against E. faecalis. The combined effect of silver nanoparticles and laser disinfection against E. faecalis holds a promising treatment modality for eradicating resistant pathogens and biofilms embedded deep inside the dentinal tubules that are not amenable to conventional disinfection protocols in root canals.