Title: Antimicrobial effect of alexidine and chlorhexidine against Enterococcus faecalis infection
Abstract: A previous study demonstrated that alexidine has greater affinity for the major virulence factors of bacteria than chlorhexidine. The aim of this study was to compare the antimicrobial activity of 1% alexidine with that of 2% chlorhexidine using Enterococcus faecalis-infected dentin blocks. Sixty bovine dentin blocks were prepared and randomly divided into six groups of 10 each. E. faecalis was inoculated on 60 dentin blocks using the Luppens apparatus for 24 h and then the dentin blocks were soaked in 2% chlorhexidine or 1% alexidine solutions for 5 and 10 min, respectively. Sterile saline was used as a control. The antimicrobial efficacy was assessed by counting the number of bacteria adhering to the dentin surface and observing the degradation of bacterial shape or membrane rupture under a scanning electron microscope. Significantly fewer bacteria were observed in the 2% chlorhexidine- or 1% alexidine-soaked groups than in the control group (P<0.05). However, there was no significant difference in the number of bacteria adhering to the dentinal surface between the two experimental groups or between the two soaking time groups (P>0.05). Ruptured or antiseptic-attached bacteria were more frequently observed in the 10-min-soaked chlorhexidine and alexidine groups than in the 5-min-soaked chlorhexidine and alexidine groups. In conclusion, 10-min soaking with 1% alexidine or 2% chlorhexidine can be effective against E. faecalis infection. The new antiseptic alexidine disinfects root canals as effectively as the commonly used chlorhexidine, a study by Kee-Yeon Kum of the Seoul National University School of Dentistry in South Korea and co-workers has shown. The root canal’s complex anatomy is prone to infection following treatment, so is treated with combinations of antiseptics. Chlorhexidine interacts poorly with the ubiquitously used sodium hypochlorite. Kum and co-workers therefore tested the efficacy of alexidine — which interacts well with sodium hypochlorite — against Enterococcus faecalis, a major cause of persistent infections. The researchers soaked blocks of bovine root canal, infected with E. faecalis, in 1% alexidine or 2% chlorhexidine for 5 or 10 minutes. Visualization of intact cells using scanning electron microscopy showed that alexidine and chlorhexidine are equally effective against E. faecalis, and that 5 minutes of soaking is required.