Efficacy of Disinfection of Dental Stone Casts: Virkon Versus Sodium Hypochlorite

Objectives: The purpose of this 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 diameters of 10mm were prepared and used as carriers of bacterial inoculums. They were individually inocu- lated by soaking in broth culture media containing each of the four selected microorgan- isms. Different concentrations of Virkon and hypochlorite solutions were prepared using distilled water and were sprayed on the surfaces of dental casts contaminated with Staphy- lococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis and Candida albicans. Pour- plate technique was used to evaluate the antimicrobial efficacy of each solution. Microbi- cidal effect was calculated according to the log10 of control colony counts minus the log10 of the remaining colony counts after the antimicrobial procedure. Statistical differ- ence was assessed using the Kruskal Wallis and Man Whitney-U tests (P<0.05). Results: We observed different bactericidal effects of Virkon at various concentrations; 1% Virkon killed S. aureus, P aeruginosa, and C. albicans, while 3% Virkon solution was required to kill B. subtilis. For S. aureus, P. aeruginosa, and C. albicans, no significant dif- ference was observed between 1% Virkon and 0.525% sodium 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 toxicity and good environmental compatibility, it may be recommended as an antimicrobial disinfectant for dental stone casts as non-critical items.