Effect of Immersion Disinfection of Alginate Impressions in Sodium Dichloroisocyanurate

Objectives: To prevent transmission of infectious diseases during dental treatment, impressions are needed to be disinfected. Sodium dichloroisocyanurate (SDIC) is a kind of which internationally promotes highly effective, low harmful, fast sterilization disinfectant. In this study, we examined the disinfection effect of SDIC on microorganisms attached to impression materials.
Methods: Exponentially growing E. coli, S. aureus, C. albicans, S. mutans and dental plaque were collected and suspended in PBS. Ten microliters of the bacterial suspension was exposed for 0.5, 1, 3, 5 and 10 min to 1 ml of the 10, 100, 1,000 and 10,000 ppm SDIC solutions, or the same volume of PBS as a control. After exposure, 10-fold serial dilution was performed in PBS and 100 μl of each dilution was spread onto a brain heart infusion (BHI) blood agar plate. To evaluate the bactericidal effect of SDIC solutions to oral bacteria on the dental impression surface, BHI agar was poured to the impression instead of gypsum and cultivated for 5 days. The surface of BHI agar was irradiated with UV to determine the presence of bacterial colonies. To confirm the influence of SDIC solutions on the surface roughness of dental casts and S. mutans biofilm removed by the disinfectant. These were observed by scanning electron microscope.
Results: All bacterial strains including plaque bacteria were disinfected by SDIC solutions in a dose-dependent manner. Oral bacteria adhered to the surface of the impression obviously decreased by 30 min immersion in 1,000 ppm SDIC solution. The 30 min immersion in 1,000 ppm SDIC solution had no effect on surface roughness of dental casts.
Conclusions: These results suggest that to immerse the impressions in 1,000 ppm SDIC solution for 30 min is effective for disinfection. It is considered that this simple manipulative method is useful for good clinical practice.