Evaluating Antimicrobial Efficacy of Dentifrices Using a New Biofilm Method

Objectives: To assess antibacterial efficacy of dentifrices with a new in-vitro biofilm method (MBEC-ATP) and introduce this method in a clinical study for dentifrice antibacterial efficacy evaluation.
Methods: MBEC Assay® Biofilm Inoculator was treated by using different dentifrice slurry: Negative control dentifrice with 0.243% NaF, 0.454% SnF2 gluconate chelated dentifrice A with sodium hexametaphosphate, 0.454% SnF2 dentifrice B with pentasodium triphosphate and Dual-Zinc (zinc oxide, zinc citrate) dentifrice C with arginine. Biofilm was then grown on the pre-treated incubator from saliva and quantified by microbial cell viability assay. By this way, the biofilm prevention efficacy of dentifrices could be assessed. Furthermore, MBEC biofilm model was introduced into a clinical study with 36 subjects for a double blind, two treatments, four periods and cross-over study. Subjects were asked to brush their teeth with assigned product: Negative control dentifrice with 0.243% NaF and 1.16% SnCl2 dentifrice D with NaF. After brushing, saliva was collected from each subject to evaluate the impact of product use on biofilm formation via MBEC biofilm method.
Results: In in-vitro biofilm assay, dentifrice A, B and C treatments all showed significantly less biofilm formation compared to the negative control dentifrice(p<0.05); in addition, dentifrice A treatment showed significantly less biofilm formation than dentifrice B and C (p<0.05). In clinical study, dentifrice D treatment showed significantly less biofilm formation compared to the negative control dentifrice (p<0.05).
Conclusions: This research demonstrated superior antibacterial efficacy of the 0.454% SnF2 gluconate chelated dentifrice with sodium hexametaphosphate relative to a SnF2 dentifrice with pentasodium triphosphate and a Dual-Zinc (zinc oxide, zinc citrate) dentifrice in this in-vitro MBEC biofilm model; in addition, superior antibacterial efficacy of the 1.16% SnCl₂ dentifrice with NaF relative to a negative control dentifrice was further demonstrated in a clinical study by introducing MBEC biofilm model as a new endpoint measurement.