Antimicrobial activity of endodontic paste prepared with tetracycline, thiamphenicol and zinc oxide assessed using agar diffusion method

Objective: The purpose of this study was to evaluate the antimicrobial effects of endodontic paste prepared with tetracycline, thiamphenicol and zinc oxide. Methods: B. cereus, C. difficile, E. coli, F. nucleatum, S. aureus, S. epidermidis and C. albicans were inoculated in Mueller-Hinton agar and broth and incubated for 24 h. Cotton swabs charged with a bacterial or fungal suspension were inoculated in wells of Muller-Hinton agar plates.Each well was then filled with endodontic paste or with their individual components (tetracycline, zinc oxide or thiamphenicol). Calcium hydroxide and two concentrated oil compounds, tricresol formalin and camphorated paramonochlorophenol, were also tested. The plates inoculated with aerobic bacteria were incubated for 20 h. Those inoculated with anaerobic bacteria were incubated anaerobically using an Anaerobic GasPak System at 35°C for 72 h. Results: Zinc oxide and calcium hydroxide demonstrated a low level of antimicrobial activity. Zones of inhibition induced by tricresol formalin and camphorated paramonochlorophenol were similar to that shown by the endodontic paste. Tricresol formalin gave a largerzone of inhibition than camphorated paramonochlorophenol for the microorganisms tested. Conclusion: The results obtained demonstrate the effectiveness of this paste and indicate its use in the treatment of pulpal infection, especially in Pediatric Dentistry.