A comparative study on the antimicrobial activity of irreversible hydrocolloid mixed with silver nanoparticles and chlorhexidine

Background: Impressions taken from patients have the potential of cross‑transmission of infection among dentistry personnel. The present study aimed to compare the antimicrobial activity of chlorhexidine (CHX) and silver nanoparticles (AgNPs) combined with irreversible hydrocolloid. Materials and Methods: This experimental study examined the in vitro antimicrobial effects of irreversible hydrocolloid mixed with silver nanoparticles and chlorhexidine using four groups, namely CHX (0.2%) solution and mouthwash mixed with irreversible hydrocolloid Groups 1 and 2), AgNPs (0.1 and 0.2%) (Groups 3 and 4), and specimens mixed with distilled water as a control group (Group 5) on bacterial strains, namely, Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus epidermidis through disc diffusion method. There were three replications per bacterial species. As data were not normally distributed, Kruskal–Wallis test was used at a significance level of 0.05. Results: No antimicrobial activity was observed in the control groups. In S. aureus, CHX mouthwash had the highest antimicrobial activity, and AgNPs 0.1% and 0.2% groups had lower antimicrobial activity, and there was a significant difference between the two concentrations of AgNPs (P < 0.05). In E. faecalis, the effects of CHX compounds and AgNPs 0.2% were similar to each other and were higher than the effect of AgNPs 0.1% (P < 0.05). In E. coli, CHX compounds exhibited the highest efficacy relative to other materials (P < 0.05), and the AgNPs had no effect. In P. aeruginosa, AgNPs showed the highest growth inhibition zone, which had a significant difference compared to other materials (P ≤ 0.01), whereas the CHX compounds were not effective. In S. epidermidis, the effect of CHX compounds was similar to one another and was higher than the effect of AgNPs (P ≤ 0.01). Conclusion: According to our observations, the antimicrobial activity of AgNPs at 0.1 and 0.2% against five tested bacterial strains was similar to those of pure CHX 0.2% solution and CHX 0.2% mouthwash.