In vitro antimicrobial activity of irreversible hydrocolloid impressions against 12 oral microorganisms.

This study evaluated in vitro the antimicrobial activity of irreversible hydrocolloids (one containing an antimicrobial agent) prepared with water or with a 0.2% chlorhexidine digluconate solution against 12 strains of the oral microbiota. Twenty specimens (0.5x1.0 cm) for each group (1. Jeltrate mixed with water; 2. Jeltrate mixed with 0.2% chlorhexidine digluconate solution; 3. Greengel mixed with water; 4. Greengel mixed with 0.2% chlorhexidine digluconate solution) were prepared under sterile conditions and placed in culture media inoculated with the indicator strains. After incubation in aerobiosis or microaerophilia, inhibition of the microbial growth was measured and the results were interpreted. The normal adherence curve revealed a non-normal distribution of the data, so the non-parametric Friedman Test was performed (p<0.05). The antimicrobial activity of the groups was classified in the following order: 1, 3, 4, and 2. The results suggest that the method of preparing irreversible hydrocolloids with a 0.2% digluconate chlorhexidine solution is more effective than the incorporation of an antimicrobial agent in the powder to reduce cross-contamination caused by impressions.