A glass filler manufacturing process and product which enable the manufacture of dental composite and dental cement products having superior product stability and also having superior physical properties. The process makes use of barium glass filler and strontium glass filler, which have high-radiopacity properties but could not previously be used for dental composites and dental cement. By simply coating the surface of the barium glass or strontium glass filler with an oxide having acid-resistance properties, and then following with a heat-treatment process, a suitable dental composite can be produced.