Technological Methods for Increasing the Fluorine Content in SrO–Al2O3–P2O3–SiO2–F Glass for Glass-Ionomer Cement

The influence of the technological glass-melting parameters of the selected composition in the SrO–Al₂O₃–P₂O₃–SiO₂–F system on the value of the refractive index and the amount of fluorine remaining in the glass structure post-melting was investigated. The lowering of the melting temperature combined with tableting of the charge [batch] increases fluorine absorption in the glass up to 17 wt.% at the same time, and the value of the refractive index reduction to n_D = 1.49. It was experimentally established that in the multicomponent glass selected for glass-ionomer cements with two glass-forming oxides (SiO₂ and P₂O₂) and a high Al₂O₃ content, each wt.% of fluorine reduces the refractive index by about 3.5 × 10 ^–4 units.