Antimicrobial Effects of Propolis, Calcium Hydroxide, Triple Antibiotic Paste, and Modified Triple Antibiotic Paste on Tubular Dentin Inoculated with a Dual-Species Biofilm: an Ex Vivo Study

This study aimed to compare the antimicrobial effects of Propolis, Calcium Hydroxide (CH), Triple Antibiotic Paste (TAP), and modified TAP (mTAP) as intracanal medicaments on tubular dentin inoculated with a dual-species biofilm. In this ex vivo study, dentin cylinders were obtained from the root canals of 56 single-rooted extracted teeth, which were instrumented and inoculated with Enterococcus faecalis (E. faecalis) and Actinomyces naeslundii (A. naeslundii) suspensions to allow biofilm formation. After that, the cylinders were randomly assigned to five groups for a 7-day exposure to Propolis, TAP, mTAP (penicillin G), and Calcium Hydroxide (CH), and a no-medicament negative control group. Colonies were counted in dentin samples obtained from 200 μm to 400 μm depths and analyzed using ANOVA, Shapiro-Wilk, Levene, Tukey, robust Welch, Games-Howell, Fisher’s exact, Wilcoxon, and paired t tests (α = 0.05). All medicaments significantly decreased the colony counts (P < 0.05). CH, TAP, and mTAP showed similar optimal efficacy at both depths, whereas Propolis caused a significant reduction in bacterial count only at 200 μm (P = 0.047). Effect sizes were very high for both microorganisms. Dentin depth had a significant effect on the bacterial count of both microorganisms, and the load of both microorganisms was significantly lower at 400 μm than 200 μm depth (P < 0.001). TAP and mTAP demonstrated high efficacy, and CH showed acceptable efficacy for elimination of E. faecalis and A. naeslundii dual-species biofilm. Propolis showed lower efficacy, highlighting the need for further modifications to enhance its penetration depth.