A fluoride releasing dental prosthesis copolymer for oral biofilm control

Abstract

Microbial biofilms on removable oral appliances can act as reservoirs for pathogens that contribute to oral diseases such as candidiasis and root caries. In this study, we evaluated the efficacy of a new fluoride-releasing copolymer on biofilms formed by three acidogenic microorganisms, C. albicans, S. mutans and L. casei. In all experiments, two materials were studied: chemically-activated copolymers of methyl methacrylate and 2-hydroxyethyl methacrylate with polymethyl methacrylate powder. For one group, 30% NaF was added at the expense of some of the PMMA. The effect that autoclaving had on important parameters such as chemical composition, roughness and fluoride release was analysed. Samples were fitted into two polysulfone Modified Robbins Devices. Single- and mixed-species biofilms were cultured for 48 h, harvested, and microorganisms were quantified by total viable counts and quantitative PCR. The pH was monitored during mixed species biofilm formation. Autoclaving did not alter the chemical composition of either material, as measured by infra-red spectroscopy. However, it did cause a significant increase in roughness of the fluoridated materials (T-test, p<0.05). Fluoride release was unaffected by autoclaving, and high rates of fluoride (>300 μg/cm2.day) were released from fluoridated samples for up to 6 days, followed by low levels of release for 6 months. The inclusion of fluoride within the copolymer significantly reduced colonisation by C. albicans, S. mutans and L. casei in mixed-species biofilms (T-test, p<0.05). However, when microorganisms were grown in single-species biofilms, all the three organisms were not significantly (T-test, p>0.05) reduced. Fluoride suppressed the acidogenicity of biofilms for up to 24 h. In conclusion, a fluoride-releasing copolymer has been developed to inhibit the growth of acidogenic oral biofilms in vitro. The copolymer potentially has major benefits for oral healthcare in wearers of removable oral appliances.