A combination of zinc and arginine disrupt the mechanical integrity of dental biofilms

Abstract

Mechanical cleaning remains the standard of care for maintaining oral hygiene. However, mechanical cleaning is often augmented with active therapeutics that further promote oral health. A dentifrice, consisting of the “Dual Zinc plus Arginine” (DZA) technology, was found to be effective at controlling bacteria using in vitro laboratory studies, translating to clinical efficacy to deliver plaque and gingivitis reduction benefits. Here we used biophysical analyses and confocal laser scanning microscopy, to understand how DZA dentifrice impacted the mechanical properties of dental plaque biofilms, with the objective of determining if changes to biofilm rheology enhances the removal of dental plaque. Using both uniaxial mechanical indentation and an adapted rotating-disc rheometry assay, it was found that DZA treatment compromised biofilm mechanical integrity, resulting in the biofilm being more susceptible to removal by shear forces, when compared to treatment with either arginine or zinc alone. Confocal laser scanning microscopy revealed that DZA treatment reduced the amount of extracellular polymeric slime within the biofilm, likely accounting for the reduced mechanical properties. We propose a model where arginine facilitates the entry of zinc into the biofilm, resulting in additive effects of the two activities towards dental plaque biofilms. Together, our results support the use of a dentifrice containing the Dual Zinc plus Arginine as part of daily oral hygiene regimens.

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ORCID for Paul Stoodley: orcid.org/0000-0001-6069-273X

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