Antimicrobial Activity of Maleic Acid and Combinations of Cetrimide with Chelating Agents against Enterococcus Faecalis Biofilm

Introduction: Chelating agents, such as EDTA or citric acid, can be incorporated into irrigants in order to provide different properties in a single compound. Maleic acid has recently been proposed as an alternative irrigant to EDTA given its better smear layer removal and biocompatibility; however, its antimicrobial activity is not known. The purpose of the present study was therefore to evaluate the in vitro capacity of maleic acid in eradicating Enterococcus faecalis biofilms and to evaluate the combinations of cetrimide with maleic acid, citric acid, and EDTA. Methods: E. faecalis biofilms were grown in the MBEC high-throughput device (Innovotech; Edmonton, Alberta, Canada) for 24 hours and exposed to the irrigating solutions for 30 seconds and 1 and 2 minutes. "Eradication" was defined as 100% bacterial kill. The Student t test was used to compare the efficacy of the irrigant combinations. Results: Maleic acid eradicated E. faecalis biofilms at a concentration of 0.88% after 30 seconds and at 0.11% after 2 minutes of contact time. When combined with 0.2% cetrimide, it eradicated the biofilms at all three times of exposure. The combination of 0.2% cetrimide with either 15% EDTA or 15% citric acid gave 100% bacterial kill after one minute of contact with the biofilms. Conclusions: Maleic acid showed antimicrobial activity against E. faecalis biofilm both alone or in association with cetrimide from 30 seconds onward and the combination of EDTA and citric acid with cetrimide eradicated biofilm after 1 minute of contact. (J Endod 2010;36:1673-1675)