Clinical Anti-microbial Efficacy of New Zinc Citrate Dentifrice Formulation

Objectives: Zinc citrate finds wide use in cosmetics and toothpastes. Clinical studies demonstrate the effects of dentifrices containing 2% zinc citrate. This study compared the antimicrobial efficacy of a new dentifrice formulated with 1% zinc citrate (test) in comparison to a fluoride dentifrice (control). Methods: A crossover design study enrolled 18 adults. Subjects completed a 1-week washout with a commercially available fluoride dentifrice and refrained from oral hygiene the morning of baseline sample collection. Anaerobic bacteria and oral streptococci were enumerated from baseline samples of plaque from teeth and along the gingiva, saliva and scrapings from cheek mucosa, tongue. For the next 13 days, subjects brushed twice daily with a randomly assigned dentifrice. Subjects arrived on day 14 prior to oral hygiene and samples of plaque, saliva and scrapings from cheek, tongue collected for post-treatment microbial analysis. Study subjects completed a second 1 week washout period prior to repeating the protocol with the alternate dentifrice. Microbial counts from all phases of the study were log10 transformed for statistical analyses. Results: Subjects provided test dentifrice demonstrated reductions in both anaerobic and oral streptococci from all intra-oral locations. Brushing with test dentifrice resulted in a 69.7%, 51.4%, 47.3% and 45.1% decrease in anaerobic bacteria from plaque, tongue, cheek and saliva respectively versus baseline (p<0.05). Similarly, streptococcal counts declined by 64.5%, 52.1%, 44.4% and 48.3% respectively, (p<0.05). Subjects provided the test dentifrice demonstrated significant reductions in all overnight samples on day 14 versus the control paste (p<0.05). Plaque, tongue, cheek and salivary anaerobic bacteria were 46.2%, 19.9%, 23.9% and 29.7% lower for test versus control (p<0.05). Similarly, streptococci were reduced by 47.5%, 19.0%, 25.2% and 31.3% respectively for test (p<0.05). Conclusions: Brushing with the 1% zinc citrate dentifrice resulted in significant reductions in bacteria from all intra-oral locations for a healthier mouth.