Antimicrobial and antibiofilm activities of neem and myrrh extracts against Enterococcus faecalis in dentin specimens.

Abstract

Background: Enterococcus faecalis is a primary oral pathogen responsible for root canal treatment failures. The clinical use of conventional root canal disinfectants may be associated with cytotoxicity and other unfavorable effects.

Objectives: The aim of the study was to assess and compare the antimicrobial effect of Azadirachta indica (neem) and Commiphora molmol (myrrh) extracts against E. faecalis biofilm in dentin samples.

Material and methods: The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of neem and myrrh extracts against E. faecalis (ATCC 29212) were determined. Human dentin discs were prepared and inoculated with E. faecalis for 21 days. The antibiofilm activities of neem and myrrh extracts were compared using colony forming unit (CFU) assays, cell proliferation assays and live/dead fluorescence microscopy. A 5.25% sodium hypochlorite (NaOCl) solution and 2% chlorhexidine (CHX) were used as standard disinfectants.

Results: The MIC values for the neem and myrrh extracts were 0.0312 mg/mL and 0.0156 mg/mL, respectively, while the MBC values were 0.0625 mg/mL and 0.0312 mg/mL, respectively. The CFU assay revealed a significant decrease in bacterial counts in the neem and myrrh groups. Similarly, cell counting kit-8 (CCK-8) assays demonstrated decreased bacterial viability in the neem and myrrh groups compared with the phosphate-buffered saline (PBS) group. Furthermore, live/dead fluorescence microscopy confirmed the antibacterial effects of both extracts against E. faecalis.

Conclusions: Myrrh and neem extracts showed promising antimicrobial potential as root canal disinfectants. These natural agents may serve as effective alternatives to conventional chemical endodontic irrigants.