Background and Aim: Researches have shown that bacteria play the main role in development of pulpal and periapical diseases. Chemo-mechanical cleaning of infected root-canal system can not remove all of the microorganisms. Thus interappointment medicaments are necessary to aid this goal. Calcium hydroxide is one of the most useful medicaments in root canal therapy, but this medicament can not eliminated all of the bacteria in root canal system. Carvacrol is an edible plant extract that has antimicrobial and anti-inflammatory effects. If this extract is effective against endodontic bacteria, it can be used as an root canal medicament.

Materials and Methods: In this experimental study, Initially, MIC and MBC of carvacrol detected with Macro broth dilution method and determined as 0.3% and 0.6%, respectively. After that, 30 single root and single canal extracted human teeth were used in this study. The number of specimens determined in a pilot study on 4 extracted teeth. After preparation to apical size # 30 with hand and rotary instruments, teeth were randomly divided into two experimental and two control groups. After culturing Enterococcus faecalis in prepared canals, we used emulsion of 0.6% carvacrol and calcium hydroxide in two A and B experimental groups for 7 days as the intracanal medicament. Microbial samples obtained before and after experiment. Then, canals with negative culture selected to obtain dentinal shaving to culture. Data obtained from microbiological samples analyzed with kruskal-wallis and Bonferroni tests.

Results: Results of this study showed that emulsion of 0.6% carvacrol has no significant difference with calcium hydroxide in elimination enterococcus faecalis after 7 days dressing (p>0.05).

Conclusion: Carvacrol can be used as an intrappointment intracanal medicament.