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

Objectives: 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. Materials and Methods: In this ex vivo study, dentin cylinders were obtained from the root canals of 56 single-rooted extracted teeth that were instrumented and inoculated with Enterococcus faecalis ( E. faecalis ) and Actinomyces naeslundii ( A. naeslundii ) susentions in order to biofilms formation. After that, the cylinders were randomly assigned to 5 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 and 400 µm depths and analyzed by ANOVA, Shapiro-Wilk, Levene, Tukey, robust Welch, Games-Howell, Fisher’s exact, Wilcoxon, and paired t tests (alpha=0.05). Results: All medicaments significantly decreased the colony count (P<0.05). CH, TAP, and mTAP had equally optimal efficacy at both depths; while, propolis caused a significant reduction in bacterial count only at 200 µm (P=0.047). The 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). Conclusion: TAP and mTAP showed high efficacy, and CH should acceptable efficacy for elimination of E. faecalis and A. naeslundii double-species biofilm. Propolis showed lower efficacy, highlighting the need for further modifications to enhance its penetration depth.