Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 12 3 2015 10 12 206 215 EN Elnaz Moslehifard Assistant Professor, Department of Prosthodontics, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran Farzaneh Lotfipour Associate Professor, Faculty of Pharmacy, Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran Mahmood Robati Anaraki Assistant Professor, Department of Prosthodontics, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran Elnaz Shafee Assistant Professor, Department of Prosthodontics, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran Shabnam Tamjid-shabestari Assistant Professor, Department of Pediatric, Faculty of Dentistry, Zanjan University of Medical Sciences, Zanjan, Iran Tahereh Ghaffari Assistant Professor, Department of Prosthodontics, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran 2015 10 11 2015 10 11 Objectives: The purpose of this experimental study was to compare the disinfection efficacy of sodium hypochlorite and peroxygenic acid (Virkon) solutions for dental stone casts contaminated with microbial strains. Materials and Methods: A total of 960 spherical stone beads with a diameter of 10 mm were prepared and used as carriers of bacterial inoculums. They were individually inoculated by soaking in broth culture media containing each of the four understudy microorganisms. Different concentrations of Virkon and hypochlorite solutions were prepared using distilled water and then were sprayed on the surfaces of dental casts contaminated with Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis and Candida albicans. The pour plate technique was used to evaluate the antimicrobi- al efficacy of each solution. Microbicidal effect (ME) was calculated according to the log10 of control colony counts minus the log10 of the remaining colony counts after the antimicrobial procedure. Statistical difference was assessed using the Kruskal Wallis and the Man Whitney U tests with a significance of 95%. Results: We observed different bactericidal effects of Virkon at various concentra- tions; 1% Virkon killed S. aureus, P aeruginosa, and Candida albicans, while 3% Virkon solution was required to kill B. subtilis. For S. aureus, P. aeruginosa, and C. albicans, no significant difference was observed between1% Virkon and 0.525% so- dium hypochlorite (P >0.05). For B. subtilis, the efficacy of 3% Virkon and 0.525%sodium hypochlorite was not significantly different (P >0.999). Conclusion: According to the obtained results for Virkon and based on its low toxici- ty and good environmental compatibility, it may be recommended as an antimicrobial disinfectant for dental stone casts as non-critical items. https://fid.tums.ac.ir/index.php/fid/article/view/288 https://fid.tums.ac.ir/index.php/fid/article/download/288/273