Antimicrobial efficacy of amine fluoride based tooth gels compared to a toothpaste in a phase 2/step 2 in-vitro test model

The aim of the present study was to determine the antimicrobial effect of various gel formulations on plaque formation; different tooth gels were compared to a toothpaste containing comparable antimicrobial ingredients with regard to its microbiocidal activity. The study was conducted under the assumption, that a chief requirement for the prevention of plaque formation is the combination of mechanical removal and antimicrobial activity, and not the sole capability of mechanical plaque removal. Ledermix(®) fluoride gel as commercially available with preservative, and without preservative and perfume oils, Elmex(®) gelée, and Meridol(®) toothpaste were tested in a standardized in-vitro test modification of the quantitative suspension test EN 1040. Instead of testing in a suspension, the respective product was directly placed on a standardized contaminated sterile stainless steel disk without adding any bio-burden. 50% egg yolk in Aqua dest. was used as a neutralizer. Within 1 min, Elmex(®) gelée showed a RF >5 log(10) against S. pyogenes and S. sanguinis. Against S. mutans, a log(10) RF of ≥5 was achieved after 2 min, against C. albicans after 5 min, and against P. aeruginosa after 10 min S. aureus was the most difficult organisms to be reduced. After an application time of 10 min, only a log(10) RF of 2.4 was achieved. Ledermix exceeded the antimicrobial efficacy of Elmex(®) gelée against S. mutans and C. albicans and was already effective against these organisms after 1 min, but did not show the same antimicrobial efficacy as Elmex(®) gelée against P. aeruginosa. Similar to Elmex(®) gelée, a required reduction of >5 log(10) for antimicrobials under no organic challenge was not achieved against S. aureus. Ledermix(®) fluoride gel without preservatives and Ledermix(®) fluoride gel without preservatives and perfume oil did not show the antimicrobial efficacy of the standard Ledermix(®) fluoride gel formulation, indicating that the observed antimicrobial efficacy is chiefly based on the preservative, and possibly the perfume oil. Compared to the tested gels, Meridol(®) toothpaste was less effective and reached any antimicrobial effect >5 log(10) only against S. sanguinis after 10 min. All unmodified tested gels showed an antimicrobial effect. Because no relevant antimicrobial efficacy against plaque forming bacteria was achieved within 2 min, in practice, an anti-plaque forming effect based on the antimicrobial action of gels cannot be assumed when used in the