Microbiological appraisal of three different brands of commercially available irreversible hydrocolloid impression materials: an in vitro study.

AIM To evaluate factory-sealed containers of three different commercially available irreversible hydrocolloid impression materials for their microbial contamination and the type of microorganisms present. MATERIALS AND METHODS Thirty-six measured samples were taken of each brand and placed on chocolate agar plates or in thioglycolate broth tubes and were incubated along with appropriate parallel controls. After incubation, colonies were enumerated and identified using standard microbiological methods. RESULTS The three brands contained viable microorganisms in 90% of the samples. Samples from the top, middle and bottom layers had approximately equal contamination frequencies. The concentration of organism varied from 25 to 74 CFUs per gram of contaminated sample. CONCLUSION AND CLINICAL SIGNIFICANCE The samples contained viable microorganism which may be potentially dangerous to immunocompromised patients.