Objective: To evaluate the anti-plaque efficacy of a dentifrice containing 1% Zinc Citrate using a dynamic in vitro biofilm model.
Methods: A High-throughput dynamic Biofilm Model, also known as Artificial Mouth (Chen et al, IADR-Abstract #2573, 2009) was used for evaluating the anti-plaque efficacy of a dentifrice containing 1% Zinc Citrate. Biofilms were grown on hydroxyapatite discs (HADs) in a multi-chamber flowcell system with continuous medium supply @37oC. After 6-hour growth, the HADs were treated with dentifrice/water (1:2, w/w) slurry for 1 minute, rinsed with water for 10 seconds, and then continued the incubation for another 18 hours. After that, the plaque on HADs was suspended and measured at OD630. Furthermore, the suspension was 10-fold serially diluted with saline solution and plated on lead acetate agar plates. After 72-hour anaerobic incubation, the VSC-producing bacteria with black colonies were counted.
Results:
| TCN Toothpaste (positive control) | 1% Zinc Citrate Dentifrice | Regular Fluoride Toothpaste (negative control) |
OD630 | 0.242±0.080* | 0.569±0.065* | 0.648±0.073 |
VSC-producing bacterial counts (Log CFU/ml) | 6.22±0.08* | 9.98±0.02* | 11.93±0.05 |
Conclusions: The data showed that 1% Zinc Citrate dentifrice provided significant growth inhibition of dental biofilm. It also reduced VSC-producing bacteria significantly. These in vitro results correlated very well with our clinical and ex vivo studies. This study concluded that: i) 1% Zinc Citrate dentifrice possessed significant anti-plaque efficacy than regular fluoride toothpaste, as well as anti-malodor producing bacteria effect. ii) The Artificial Mouth Model could provide reliable and collaborative data with clinical evaluation.