Bioactive Glasses Based on Sodium Disilicate and Tetracalcium Phosphate Compositions for Bone Grafting Applications

Development of synthetic bone grafts characterized by ideal properties is still a critical issue. This study aims at synthesizing osteogenic bone graft composed of bioactive glass based on sodium disilicate and tetracalcium phosphate phases and tailoring its physical and biological properties by changing the ratio between the two phases. Five bioactive glass samples (G1, G2, G3, G4, and G5) were prepared. Density, molar volume, Vickers’s microhardness, glass degradation potential, pH changes, and weight loss of prepared samples in simulated body fluid at different time intervals were measured. Hydroxyapatite (HAP) formation capability was inspected using scanning electron microscopy and energy dispersive x-ray analysis (SEM-EDX). Biocompatibility of the glasses was evaluated against human normal cell line and periodontal ligament derived stem cells via MTT cytotoxicity and alkaline phosphatase tests, respectively. The results showed that bioactive glass samples revealed gradual increase in density values from G1 to G5. G1 had the highest microhardness value (6.9 GPa), while G2 was the lowest (5.2 GPa). All samples induced the formation of bone-like apatite precipitates with a range of 1.78—2.37 Ca/P ratio, precipitates induced by G2 showed the closest Ca/P ratio to the stoichiometric HAP. The degradation increased by increasing tetracalcium phosphate phase. Finally, all glass samples did not show significant cytotoxic effect, and they all revealed alkaline phosphatase enzyme releasing capability. In conclusion, bioactive glass designed from sodium disilicate and tetracalcium phosphate phases provides promising osteogenic bone grafts with tailored biodegradation rates. G2 bioactive glass is especially recommended owing to its higher reactivity and in vitro bioactivity.