Microbial contamination in four commercially available denture adhesives.

Four brands of commercially available powder denture adhesives were tested for microbial contamination. Sterile Petri plates that contained either brain-heart infusion (BHI) or Sabouraud's (SAB) agar were inoculated with 0.5 gm samples of each adhesive. The BHI plates were incubated aerobically and anaerobically at 35 degrees C and the SAB plates aerobically at 30 degrees C for 2 weeks. The sterility of these procedures was confirmed by incubating uninoculated control plates. All bottles of powder denture adhesive tested contained microorganisms. Both bacterial and fungal growth were noted. The containers of adhesive were then subjected to 10 minutes of microwave energy (650 W) to sterilize the adhesive material. After retesting, any bottles still contaminated were subjected to additional 10 minutes of microwave exposure and then retested. Seven of 24 bottles still showed evidence of microbial contamination after exposure to microwave energy. Of the seven bottles, five were of one brand. A Fisher's exact test showed significant differences in the percentage of contaminated samples between that and the other brands (p < 0.05). Microwave energy reduced microbial contamination in all samples but failed to completely sterilize seven of 24 samples.