Residual activity of chelating agents and their combinations with cetrimide on root canals infected with Enterococcus faecalis.

The use of chelating agents in endodontic treatment is required to remove the smear layer and to achieve better disinfection within the root canal system. The aim of this study was to evaluate the residual antimicrobial activity of 17% ethylenediaminetetraacetic acid (EDTA), 7% maleic acid (MA), and 10% lactic acid (LA) alone and combined with 0.2% cetrimide (CTR) on infected root canals with Enterococcus faecalis. Biofilms of E. faecalis were grown in uniradicular roots for 4 weeks. After preparation the roots were randomly divided into 6 groups (n = 15) according to the final irrigation regimen as follows: 5 mL of 17% EDTA; 5 mL of 17% EDTA + 0.2% CTR; 5 mL of 7% MA; 5 mL of 7% MA + 0.2% CTR; 5 mL of 10% LA; and 5 mL of 10% LA + 0.2% CTR. Samples were collected for 60 days to denote the presence of bacterial growth. Fisher and Pearson χ(2) tests were applied to compare the percentages of specimens without E. faecalis regrowth at all the time periods. There were significant differences in bacterial regrowth between the groups with and without CTR. There were not significant differences over time among the 3 groups with CTR or among the 3 without CTR. The residual activity against E. faecalis of 7% MA + 0.2% CTR, 17% EDTA + 0.2% CTR, and 10% LA + 0.2% CTR was greater than the use of chelating agents alone.