Polymerization and Characterization of a New Phosphated Poly(methyl methacrylate)

Candida albicans ready adhesion to poly(methyl-methacrylate) (PMMA) denture base material is a major factor in the etiology of denture-induced stomatitis (DIS). PMMA surface modification to expose a negative charge inhibits C. albicans adhesion and enhances adsorption of cationic salivary antimicrobial peptides onto the surface. Development of denture base resins with a negative charge throughout the material may be beneficial. Objective: The purpose of this study was to add phosphate groups throughout PMMA to generate a novel anionic denture resin. Methods: The six polymers with varying amounts of phosphate were synthesized using mixtures of methyl methacrylate (MMA) and ethylene glycol methacrylate phosphate (EGMP) as monomers using the bead suspension technique. The ratios of MMA/EGMP were 100:0(PMMA control), 95:5(5% EGMP-PMMA, E-5), 90:10(10% EGMP-PMMA, E-10), 85:15(15% EGMP-PMMA, E-15), 80:20(20% EGMP-PMMA,E-20) and 75:25(25% EGMP-PMMA, E-25) respectively. Characterization of all polymers included 31P-NMR and FTIR to verify the incorporation of phosphate in the new resins. SEM and N2 adsorption analyses were also used to characterize the polymer beads. Results: SEM and nitrogen adsorption confirmed the generation of spherical beads with a surface area similar to currently available denture base materials. FTIR spectral changes in the P-O IR stretching region (1000-1200 cm-1) were consistent with a steady increase in phosphate content of the polymer beads from 5%-25% after subtracting out the PMMA spectra. Solid state 31P- NMR spectra also showed a linear increase in phosphate intensity from 5-25% whereas the PMMA control showed no phosphate signal. Conclusion: New phosphate containing EGMP-PMMA co-polymers have been generated. Studies on the antimicrobial properties are underway. Supported by NIDCR Grant # DE016925.