Phosphate, Calcium, and Fluoride Ion Release From Polyurethane Based Microcapsules Formulated in a Resin Based Dental Varnish

Abstract

Tooth decay is a significant oral health challenge. Demineralization occurs in an acidic environment and can be further accentuated by the presence of acid producing cariogenic bacteria. As the pH decreases, the salivary fluid becomes undersaturated with calcium and phosphate ions, resulting in these ions being leached out from the enamel. Remineralization is promoted in an environment with a pH above 5.5 in the salivary fluid, especially when the saliva is supersaturated with calcium and phosphate ions.|This research was conducted to provide a method for the release of bioavailable calcium, phosphate, and fluoride ions into the oral environment in a way that can be included in a variety of dentifrices. To accomplish this, ion permeable microcapsules were synthesized that incorporated aqueous solutions of solvated calcium, phosphate or fluoride ions. It is hypothesized that the incorporation of these microcapsules into a resin varnish can provide a method for controlled release of bioavailable ions. The variables that effected the rate of ion release were studied as a function of changing the chemical structure of the microcapsules, the identity of the salt, initial salt concentration in the microcapsules and w/w% loading of the microcapsules in the varnish. It was found that 1,4-butanediol based microcapsules released at a greater rate that the ethylene glycol based microcapsules. The phosphate ion was released quickest from the resin varnish formulation followed by calcium and lastly fluoride. The rate of phosphate ion release increased at a rate greater than expected as the w/w% loading of the resin based varnish increased. During the first week, the highest rate of ion release was not from the highest initial concentration studied. After the first week, the rate of phosphate ion release increased as the initial salt concentration in the microcapsules increased. The data from these results demonstrates that ion permeable microcapsule incorporation into a dentrifice is a promising approach for promoting remineralization in the oral environment.!