Evaluation of different concentration of sodium hypochlorite for disinfection of irreversible hydrocolloid impression

Various pathogenic bacteria and viruses may be transmitted through blood and saliva, both of which may be found on the surface of impression materials. Then the disinfection of impression material, without change in dimensional stability is important. The purpose of this study was to determine the effects of different concentration of sodium hypochlorite (5.25, 2.5, 0.1,.. . 0.05 percent) and different immersion times (1 to 10, 15, 20 minutes) on disinfection of irreversible hydrocolloid impression materials. Methods & Materials: In this study, we used both gram positive and gram negative bacteria. A household bleach containing 5.25% of sodium hypochloride was used as disinfectant, the irreversible hydrocolloid impression used, was Iralgin. Minimum inhibitory concentration (MICs) were determined using macro dilution method. The contaminated hydrocolloids were then soaked in the different concentrations of NaOCl for the specified disinfection times. 0.6% sodium hypochlorite for 2 minutes was the lowest concentration preventing bacterial growth and disinfecting irreversible hydrocolloid impression in minimum time. Disinfection of irreversible hydrocolloid impressions in 0.6% solution of sodium hypochlorite for 2 minutes was as effective as the ADA protocol of 0.5% sodium hypochlorite for 10 minutes for the considered microorganisms.