In vitro antibacterial effect of different irrigating solutions on Enterococcus faecalis

Area of Science:

• Endodontics
• Microbiology
• Biomaterials

Background:

• Enterococcus faecalis is a common pathogen in persistent endodontic infections.
• Effective intracanal disinfection is crucial for endodontic treatment success.
• Evaluating irrigant efficacy against E. faecalis is essential for optimizing root canal therapy.

Purpose of the Study:

• To compare the minimum inhibitory concentration (MIC) and antibacterial effect (AE) of 2.5% sodium hypochlorite (NaOCl), 0.2% chlorhexidine gluconate (CHX), and 17% ethylenediaminetetraacetic acid (EDTA) against Enterococcus faecalis.
• To assess the efficacy of these irrigants on contaminated root dentin.

Main Methods:

• MIC and agar diffusion assays were performed to determine the inhibitory concentrations and diffusion zones.
• Antibacterial effect was evaluated on contaminated human root dentin (apical and middle portions).
• Root dentin samples were incubated with irrigants at 37°C, and viable bacterial cells were counted at 0, 4, 8, and 24 hours.

Main Results:

• MIC values were 0.2% for NaOCl and CHX, and below 5% for EDTA.
• Agar diffusion showed inhibition zones of 21 mm for NaOCl, 14 mm for CHX, and 20 mm for EDTA.
• NaOCl 2.5% completely inhibited E. faecalis for 24 hours in the apical area and 8 hours in the middle area.
• CHX 0.2% reduced bacterial load by over 5 log CFU, while EDTA 17% reduced it by over 3 log CFU at all time points.

Conclusions:

• 2.5% NaOCl exhibits superior antibacterial efficacy against Enterococcus faecalis in root dentin compared to 0.2% CHX and 17% EDTA.
• NaOCl provides sustained antibacterial activity, particularly in the apical root canal region.
• CHX and EDTA also demonstrate significant antibacterial effects, but to a lesser extent than NaOCl under the tested conditions.