Comparative antimicrobial efficacy of three intracanal medicaments in an in vitro Enterococcus faecalis root canal infection model

Enterococcus faecalis (E. faecalis) commonly persists in endodontic infections and shows high resistance to traditional intracanal medicaments like calcium hydroxide [Ca(OH)2]. Alternatives such as chlorhexidine (CHX) and RG-Dent (metronidazole, iodoform, dexamethasone) are promising, but comparative evidence, especially regarding optimal application duration, remains limited. Sixty human single-rooted teeth were prepared, sterilized, and inoculated with E. faecalis for 21 days to establish an in vitro root canal infection model. Specimens were randomly assigned to three medicament groups (RG-Dent, 2% CHX gel, Ca(OH)2; n = 20 each) with two subgroups by application duration (2 or 7 days; n = 10 each). Bacterial loads (log10 CFU/mL) were measured pre- and post-treatment. Data were analyzed using two-way ANOVA, t-tests, Tukey’s HSD (α = 0.05), and effect size calculations. All medicaments significantly reduced bacterial loads (p < 0.001). Both CHX (mean reduction 4.94 ± 0.23) and RG-Dent (4.77 ± 0.26) were significantly more effective than Ca(OH)2 (3.69 ± 0.27) (p < 0.001, d > 4). CHX showed marginal superiority over RG-Dent (p = 0.036, d = 0.69). Application duration (2 vs. 7 days) had no significant effect (p = 0.78) and there was no interaction between duration and medicament. Both 2% CHX gel and RG-Dent were significantly more effective than Ca(OH)2 against mature E. faecalis in vitro root canal infection model. Prolonged application beyond 2 days did not enhance efficacy, supporting the use of shorter medicament protocols for efficient clinical disinfection.