Dentin-preserving properties of cymbopogon nardus extract as a herbal endodontic irrigant against Enterococcus...

Enterococcus faecalis is a persistent endodontic pathogen that can survive conventional irrigation protocols. Herbal irrigants that combine antimicrobial efficacy with dentin preservation are therefore required in conservative endodontic therapy. Cymbopogon nardus (CN) contains bioactive phytochemicals; however, its effectiveness as a dentin-preserving endodontic irrigant has not been comprehensively evaluated. This study aimed to evaluate the antimicrobial, antibiofilm, cytotoxic, and dentin-protective effects of CN extract under the in vitro conditions.

Ethanolic extracts of CN were prepared at concentrations of 1%-5% (w/v) and tested against E. faecalis (ATCC 29212). Chlorhexidine 2.5% and saline were used as positive and negative controls, respectively. Antibacterial activity, biofilm inhibition, and bacterial viability were quantitatively assessed using growth inhibition (620 nm), crystal violet biofilm assay (580 nm), and MTT assay (570 nm) at 24, 48, and 72 h. Standardized human dentin specimens were prepared by root canal instrumentation and irrigated in accordance with the experimental groups. Dentin surface morphology and mineral composition were evaluated using scanning electron microscopy (SEM)/EDS, while fourier transform infrared (FTIR) spectroscopy assessed mineral and organic matrix integrity. Data were analyzed using the one-way ANOVA with least significant difference post hoc tests (P < 0.05).

CN showed concentration- and time-dependent antibacterial and antibiofilm effects, with CN 5% demonstrating the highest activity at 72 h (P < 0.05). SEM-EDS analysis indicated that CN 4%-5% preserved dentinal tubule architecture, minimized smear layer formation, and maintained a physiological Ca/P ratio (~2.0). FTIR confirmed better preservation of phosphate and amide bands compared with chemical irrigants.

Ethanolic CN extract demonstrates strong in vitro antimicrobial and antibiofilm activity while preserving dentin microstructure and mineral integrity, indicating its potential as a biocompatible herbal endodontic irrigant.