In Vitro Study to Evaluate the Antibacterial Effect of an Oxidising Agent on Ex Vivo Biofilm

To evaluate the antibacterial effect of a mouthrinse and a fluid, both containing an oxidising agent, compared with saline (negative control) and chlorhexidine (0.2%, positive control), after application to 24-hour-old biofilms.

After 24 participants had refrained from all oral hygiene measures for a period of 24 h, a voluminous biofilm sample was taken from the buccal sites of molars, smeared on a microscope slide and divided into four parts. The four samples were each coated with 5 µl of a mouth rinse solution (BMmr, blueM mouth rinsing solution, NL), a fluid (BMfl, blueM oxygen fluid, NL), chlorhexidine 0.2% (CHX) and NaCl. After 1 min, excess liquid was suctioned off, and biofilms were stained with vital fluorescent dyes for 2 min. The stained samples were covered with a cover slip, and four pictures per sample were recorded with a digital camera under the fluorescence microscope. A special image analysis program used the red and green pixels to calculate the percentage of metabolically active bacteria in the entire biofilm sample (dental biofilm vitality, VF%).

Both BMmr and BMfl reduced VF to 18.46 ± 9.59% and 19.53 ± 12.17% significantly (P 0.001) compared to NaCl, with values of 59.88 ± 10.14%. CHX revealed values of 14.35 ± 6.56%, values that were not significantly lower (P 0.001) than the other active solutions.

Both BMmr and BMfl demonstrated a statistically significant antibacterial effect compared to NaCl and showed a similar effect to CHX. However, clinical trials are needed to evaluate the efficacy of both products containing oxidising agents when used as oral rinses.