Background and purpose: Calcium hydroxide and Chlorhexidine are among common intracanal medications. Recently an herbal composition named Carvacrol has been suggested as an intracanal medication. The purpose of this study was to compare antimicrobial effect of Carvacrol, Chlorhexidine and Calcium hydroxide on Enterococcus faecalis.

Materials and methods: In this experimental study, 56 single-rooted teeth were extracted and after canal preparation, they were randomly divided into three groups (n= 16) and 2 positive and negative control groups (n= 4 per group). After sterilization by autoclave, all samples except negative control group were contaminated with Enterococcus faecalis. The root canals in group 1 were filled by Calcium hydroxide paste. Paper cones impregnated by 0.2% Chlorhexidine and 94% Carvacrol were placed in working length of root canals in group 2 and 3, respectively. Negative control group was assessed without contamination and no medication was used in positive control group. After incubation of specimens for 48 hours and canal irrigation, a sample was taken from each canal and bacterial colony growth was assessed in BHI agar. Data analysis was done in SPSS ver.20 applying Chi-square and Fishers exact test.

Results: All three groups were found effective in eliminating Enterococcus faecalis and there were no significant differences in antibacterial effect between these groups (P= 0.99).

Conclusion: Carvacrol can be recommended as an effective herbal medication for intracanal irrigation.