Antibiofilm Activity of Sodium Hypochlorite and Alkaline Tetrasodium EDTA Solutions.

INTRODUCTION: The aim of this study was to determine the antimicrobial activity of mixed alkaline tetrasodium EDTA (EDTANa4)/sodium hypochlorite (NaOCl) solutions with and without the addition of cetrimide (CTR) against Enterococcus faecalis biofilms. METHODS: The antimicrobial solutions were evaluated on a 3-week biofilm of E. faecalis grown on radicular dentin blocks. The irrigating solutions were 2.5% NaOCl group, 20% EDTANa4 group, 10% EDTANa4 group, 2.5% NaOCl/10% EDTANa4 group, 2.5% NaOCl/5% EDTANa4 group, 2.5% NaOCl/10% EDTANa4/0.2% CTR group, 2.5% NaOCl/5% EDTANa4/0.2% CTR group, and 0.9% saline solution group. Cell viability was determined by adenosine triphosphate assay, and culture techniques were used to determine colony-forming unit (CFU) counts. In groups with positive growth, the Pearson linear correlation coefficient r (-1 ≤ r ≤ 1) between relative light units (RLUs) and log10 (CFUs + 1) was calculated. The results of the bioluminescence adenosine triphosphate assay and CFUs of the groups were analyzed by means of analysis of variance and the Duncan test. RESULTS: There was Pearson correlation between RLUs and log10 (CFUs + 1). A similar reduction of RLUs in all NaOCl groups was seen, giving statistical differences with respect to the control. In the NaOCl groups there was no bacterial growth. The lowest antimicrobial efficacy was found for the EDTANa4 groups. CONCLUSIONS: Mixed alkaline EDTANa4/NaOCl solutions with and without the addition of CTR do not interfere with the antimicrobial activity of NaOCl.

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

INTRODUCTION: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Eradication of Enterococcus faecalis biofilms by cetrimide and chlorhexidine.

INTRODUCTION: Enterococcus faecalis is the most commonly isolated bacteria from root canals of teeth with persistent periapical periodontitis. Its ability to grow as a biofilm impedes the elimination of E. faecalis by using irrigating solutions. The purpose of this study was to assess the efficacy of cetrimide and chlorhexidine (CHX), alone and in association, in combined and alternating form, in eradicating biofilms of E. faecalis. METHODS: Biofilms grown in the MBEC-high-throughput device for 24 hours were exposed to irrigating solutions for 30 seconds and 1 and 2 minutes. Eradication was defined as 100% kill of biofilm bacteria. The Student t test was used to compare the efficacy of the associations of the 2 irrigants. RESULTS: Cetrimide eradicated E. faecalis biofilms at concentrations of 0.5%, 0.0312%, and 0.0078% at 30 seconds and 1 and 2 minutes of contact time, respectively. CHX did not eradicate the biofilms at any of the concentrations (4% initial concentration) or times assayed. The association of 0.1% and 0.05% cetrimide with any concentration of CHX, whether in combined or alternating application, effectively eradicated E. faecalis biofilms at all the contact times tested. Eradication was also achieved with 0.02% and 0.01% cetrimide at 2 minutes. Statistical analysis revealed significantly better results with alternating rather than combined use of cetrimide and CHX (P < .05). CONCLUSIONS: The associated use of cetrimide and CHX provided better results than their applications as single agents against E. faecalis biofilms, and the alternating application was significantly more effective than the combined mode of application.