Polymethyl methacrylate (PMMA) is a widely used denture base material. This material continues to be used as it has good working and esthetic characteristics. Despite its clinical success, it has a number of problems in use such as plaque formation on the surface of the denture. In this study, we evaluated the efficacy of a new fluoride-releasing copolymer material for reducing mixed-species biofilm formation on oral appliances.
Method:
Discs of a copolymer of methyl methacrylate and 2-hydroxyethyl methacrylate with PMMA powder were produced by chemically-activated free radical polymerisation. For one group, 30% NaF powder was added at the expense of some of the PMMA. Samples were fitted into two polysulfone Modified Robbins Devices. Mixed-species biofilms of Candida albicans, Streptococcus mutans and Lactobacillus casei were cultured for 48h, harvested, and microorganisms were quantified by total viable counts (TVCs) and quantitative PCR (qPCR). The pH of both groups was monitored during biofilm formation and fluoride release from the material was measured for six months.
Result:
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). Fluoride suppressed the acidogenicity of biofilms for up to 24 h. High rates of fluoride release (>300 µg/cm2/day) were sustained for 6 days, after which low levels of fluoride were released for 6 months.
Conclusion:
A model system has been developed for multiple-species biofilms on dental materials. The inclusion of fluoride within a copolymer resulted in a reduction in multispecies biofilm formation. This model will now be exploited to look at the effects of the fluoride-releasing material on biofilms formed by the natural microbiota of human denture plaque.