How to Design a Viscoelastic Mouth Rinse for Enhanced Active Deposition without Polymers

Abstract: In mouth rinse products, water soluble active deposition and retention in the oral environment has always been a challenge since saliva constantly flushes in the oral environment and thus can rinse away water soluble actives. In this study, a polymer/gum-free viscoelastic mouthwash with enhanced active deposition is engineered by taking advantage of the synergistic interaction between amine fluoride (AmF), an anti caries & antibacterial active, and surfactants such as cocoyl glucoside (APG) or sodium cocoyl glutamate (SCG). Surface tension measurements, dynamic light scattering, NMR, high resolution mass spectrometry (HR-MS) and X-ray photoelectron spectroscopy (XPS) were used to study these interactions. It is found that AmF can interact strongly with surfactants like APG & SCG, resulting in the formation of mixed micelles. This interaction, especially with SCG, is so strong that it can effectively compress the surfactant head group area, promoting the formation of mixed wormlike micelles and thus leading to a viscoelastic solution. XPS analysis of bovine enamel blocks treated with various formulations showed increased levels of C and N in AmF plus SCG formula, indicating an enhanced deposition compared to AmF alone and AmF plus PEG-40 castor oil formulations. By modulating the interaction between AmF and co-surfactants, the performance of the mouth rinse product can be tailored in the oral environment.