The antimicrobial effect of R-limonene and its nano emulsion on Enterococcus faecalis - In vitro study

This study aimed to evaluate the effectiveness of R-limonene and its nano emulsion formulation against Enterococcus faecalis (E. faecalis) in infected root canals. A nano emulsion containing 20% R-limonene was prepared using the phase inversion method. E. faecalis was cultivated, and MIC/MBC values were determined through the macrodilution method. Standardized E. faecalis suspensions were used to infect the root canals ex vivo. Subsequently, R-limonene, nano emulsion containing 20% R-limonene, calcium hydroxide, and sterile saline were applied to the infected root canals for 7 days at the determined MIC/MBC dose. The root canals were sampled, and droplets were plated onto Mueller-Hinton agar plates, and viable bacteria (Colony Forming Units, CFU/mL) were counted. Statistical analyzes were performed based on the data. Statistically similar efficacy was observed between test materials on the root canal samples. All test materials were significantly more effective than the saline control (p<0.05), however, none of the test materials completely eliminated E. faecalis from root canals. Although the effects of R-limonene on E. faecalis in infected root canals appeared to be like calcium hydroxide, with its broad antibacterial spectrum, gutta-percha softening and cleansing benefits, it was considered that it could considered among antimicrobials that could be used especially in endodontic retreatments alone or in synergistic combinations.