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.