Effect of CaF2 content on rate of fluoride release from filled resins

Information on the time-dependent release of fluoride from filled resins containing fluoride particles as a function of particle content and solution pH is limited. This study characterized the fluoride ion release from filled resins containing CaF2 particles as a function of filler content and pH. Urethane dimethacrylate and triethylene glycol dimethacrylate resins were used to make filled-resin disks containing 9.09, 23.08, or 33.33 mass% CaF2 filler. Fluoride ion release for the 9.09 mass% concentration was independent of pH. Increasing the filler content from 9.09 to 33.33 mass% increased the fluoride release rate in pH 4.0 buffer solution, because of greater surface degradation. Fluoride ion release from disks stored in pH 6.0 buffer solutions occurred mainly by diffusion from disk surfaces, while fluoride release from disks in pH 4.0 buffers was controlled by diffusion from disk surfaces and degeneration of the resin matrix, which exposed more CaF2 particle surface area.