プレス成形可能な歯冠材料用CaO-MgO-SiO₂-TiO₂-Ag₂O系ガラスの作製

抄録

Glass-ceramics were searched for in the systems based on CaO-MgO-SiO₂-TiO₂-Ag₂O. The glasses melted at 1500°C could be cast. The absorptions were measured. Silver colloids formed in the glasses of composition CaO⋅MgO⋅2SiO₂⋅0.375TiO₂⋅0.007Ag₂O, and CaO⋅MgO⋅2SiO₂⋅0.49TiO₂⋅0.007Ag₂O. The crystallization of diopside of these glasses are controlled by volume nucleation and growth processes. It is shown that the activation energy for crystallization of diopside decreases of these glasses. A fluidity of diopside glass was observed at 800-900°C by the viscous flow mechanism. It can be formed precisely and crystallized under pressure of 0.15MPa at 850°C for 40min, and the glass-ceramics contained crystalline diopside. The bending strength was about 350MPa. This glass-ceramics crystal phase look similar to natural teeth in color and translucency without any deformation. Such a press-forming method is superior to casting method because it is free from pores, and it can be formed lower temperature than 900°C regardless of the glass has high melting point.