Water absorption characteristics of dental microfine composite filling materials. II. Experimental materials.

Water absorption characteristics have been studied in terms of diffusion coefficient, equilibrium uptake, and solubility as a function of the volume loading of pyrolytic silica filler, for two different resins. Equilibrium uptake decreased with filler loading, but if calculated on the original volume of monomer present, gave consistent values for each resin. Triethylene glycol dimethacrylate based materials had much higher water uptake and diffusion coefficients than the urethane dimethacrylate resins. Furthermore the former exhibited higher concentration dependence of the diffusion coefficient. Diffusion coefficients were sensibly independent of filler loading.