Clinical anti-microbial efficacy of a new zinc citrate dentifrice

This crossover design clinical study compared the anti-microbial effects of a new 1% zinc citrate dentifrice with a control formulation. Thirty adults completed a washout phase and baseline samples of dental plaque, buccal mucosa, tongue, saliva, and plaque collected to enumerate anaerobes and streptococci. Subjects were randomly assigned a test dentifrice to use for the next 13 days. Oral samples similar to the baseline were collected on day 14 prior to oral hygiene for microbial analysis. The subject then placed a custom intra-oral stent with hydroxyapatite (HA) squares and brushed their teeth with their assigned dentifrice. Oral samples and HA squares were collected 5 h later for microbial analyses. This completed the study with one test dentifrice. The entire study was repeated with the alternate dentifrice after a second washout phase. Whereas baseline samples demonstrated no significant differences in microbial parameters between the two treatment groups (p > 0.05), subjects provided the zinc citrate dentifrice demonstrated 24-52% reductions in anaerobic bacteria and streptococci on day 14 versus the control paste (p < 0.05). In the 5-h post-brushing samples, subjects provided the zinc citrate toothpaste demonstrated 27-49% reductions for anaerobic bacteria and streptococci (p < 0.05). Additionally, in situ microbial biofilm formation on HA disks was significantly inhibited amongst the zinc citrate group (p < 0.05). Significant reductions in anaerobic bacteria and streptococci were observed amongst all intra-oral locations along with in situ biofilm formation after use of the zinc citrate dentifrice.