Evaluation of Antimicrobial and Cytotoxic Activity of Electron Beam Irradiated Endodontic Sealer

Abstract

Background: The persistent pathogenic microorganisms in root canal system even after chemo-mechanical preparations cause endodontic infection and failure of the treatment. Thus the filling material, in addition to its good sealing ability, should offer long term antimicrobial effect and be non-toxic to cells and dentin. Zinc Oxide Eugenol (ZOE) is the most commonly used root canal sealer in endodontics. Electron beam (e-beam) is an ionizing radiation and known to cause physiochemical and biological changes. The aim of this study was to evaluate the effect of e-beam irradiation on bioactive properties of ZOE. Methodology: The homogenous mixture of ZOE was prepared as per manufacturer's instructions and discs of 6 mm were prepared by loading the paste into sterile moulds. After complete drying discs were aseptically removed and subjected to e-beam irradiation at doses of 250 Gy, 500 Gy, 750 Gy and 1000 Gy at Microtron Centre, Mangalore University. Antimicrobial and antibiofilm properties of both control(non-irradiated) and irradiated sealer against Enterococcus faecalis, Staphylococcus aureus, Streptococcus mutans and Candida albicans were determined by well diffusion method and antibiofilm by O'Toole method, respectively. The cytotoxicity was determined by using MTT assay on human gingival fibroblasts. Results: The antimicrobial effect of ZOE was observed only against S. aureus and C. albicans. The ZOE sealer irradiated at 1000 Gy showed a significantly (P< 0.001) increased antimicrobial effect against S. aureus and C. albicans compared to control ZOE. However, the substantially increased antibiofilm activity against C. albicans was noticed in the ZOE irradiated at 250 Gy. There was no significant (P>0.05) difference in cytotoxicity between control and irradiated ZOE. Conclusion: The e-beam irradiated endodontic sealer ZOE at 1000 Gy and 250 Gy significantly enhanced the antimicrobial and antibiofilm activity respectively without changing its biocompatibility.