Effect of Dentifrices on Oral Bacteria and Ex-situ Dental Plaques

Objective: This investigation evaluated the antimicrobial effects of dentifrices augmented with triclosan/PVM/MA copolymer (Colgate® Total®; CT) or stannous fluoride in combination with sodium hexametaphosphate and zinc lactate (Crest® Pro-Health®; CPH) on dental plaque ex-situ and on planktonic cultures of oral bacteria. Methods: Oral microcosms were maintained ex-situ on glass slides in artificial saliva using a salivary inoculum for 48 h. Triplicate samples were exposed to CT or CPH for 60s. Samples were imaged immediately and up to 12h after staining with the LIVE/DEAD fluorescence dyes using a fluorescence microscope. The proportion of non-viable fluorescence as a percentage of total fluorescence was quantified by ImageJ software. An additional test utilized alamar blue fluorescence to assess immediate effects of the dentifrices on planktonic cultures of Actinomyces viscosus in comparison to untreated controls. Student's t-test evaluated statistical significance between treatments. Results: Pre-dosing plaques were highly viable as indicated by the abundance of green fluorescent material (66 % viable biomass). Following treatment, immediate viability in the plaques was markedly and significantly decreased. Treatment with CT caused a significantly greater decrease in viability in comparison to CPH (P<0.001). This observation continued for up to 12h post-exposure. Correspondingly, treatment with either dentifrice resulted in significant reductions in alamar fluorescence in comparison to untreated controls (p<0.05). Once again, the effects of CT were significantly higher than those of CPH (p<0.05). Conclusions: CT caused significant reductions in microbial viability for up to 12 hours in comparison to CPH as evidenced by comparatively more rapid and extensive inactivation of oral bacteria. This work was funded by a grant from Colgate-Palmolive Company.