Evaluation of Propolis as an Intracanal Agent in Combination with an Nd:YAG Laser for Bacterial Reduction

Introduction: This study aimed to assess the antimicrobial efficacy of propolis for an intracanal medicament in combination with an Nd:YAG laser against the biofilm of persistent endodontic pathogens: Enterococcus faecalis, Staphylococcus aureus and Candida albicans. Methods: One hundred and sixty-five extracted human premolars were included. Monospecies of four-week biofilms were cultured in root canals after the teeth were prepared chemo-mechanically. Specimens were treated with calcium hydroxide for 24 hours (G1), propolis for 24 hours (G2), Nd:YAG laser (1064 nm, 1.5 w, 15 Hz, 100 mJ/pulse, 200 µm endodontic fiber tip) (G3), propolis medicament followed by Nd:YAG laser (G4), and normal saline as the control group (G5). Dentin chips were obtained with Gates-Glidden #5, 6 and inoculated onto agar plates for microbial growth. The antimicrobial efficacy of each group was evaluated by quantifying the number of colony-forming units. Data were statistically analyzed using the Kruskal-Wallis and Mann-Whitney U test (P value<0.05). Results: All investigated groups reduced the bacterial count compared to normal saline (P value<0.05). Propolis (0.23±0.58, 0.00±0.00, 1.34±1.12 for E.f, S.a, and C.a., respectively) and Nd:YAG laser (3.19±0.51, 3.21±0.37, 3.29±0.52 for E.f, S.a, and C.a., respectively) were more effective in the reduction of all three pathogens during 24 hours, compared to calcium hydroxide (P value<0.05). The application of propolis followed by the Nd:YAG laser resulted in the complete elimination of E. faecalis and S. aureus and a significant reduction in C. albicans (0.60±0.96) (P value<0.05). Conclusion: Propolis alone or in combination with the Nd:YAG laser at low powers is highly effective against endodontic pathogens in comparison with conventional calcium hydroxide medicament.