A New Series of X-Ray-Opaque Reinforcing Fillers for Composite Materials

¹ American Dental Association Research Unit, National Bureau of Standards, Washington, DC 20234, USA, and National Bureau of Standards, Washington, DC

Clear, colorless glasses that absorb roentgen rays were prepared by melting together compounds yielding silica, barium oxide, boric oxide, and alumina. Barium oxide made the glasses radiopaque and gave the desired refractive index. Boric oxide lowered the melt viscosity, and alumina tended to stabilize the glasses. Some of these glasses seem to be suitable for use as the reinforcing fillers for composite dental restorative materials.