(A) Flexural strength, and (B) elastic modulus, of dental resin composite containing CaF2 nanoparticles. At the top, NCF denotes nanoparticles of CaF2, and WHI denotes whiskers. The x-axis denotes the corresponding CaF2/(CaF2 + whisker) mass ratio, where “0” means all whiskers and no CaF2. Each value is the mean of six measurements with the error bar showing one standard deviation (mean ± sd; n = 6).