Mechanical properties, in vitro and in vivo bioactivity assessment of Na2O-CaO-P2O5-B2O3-SiO2 glass-ceramics

Glasses having chemical composition based on Na2O-CaO-P2O5-SiO2 system were crystallized. Then, the resultant crystallized phases were examined by X-ray diffraction technique. Furthermore, density, microhardness and fracture toughness were measured. In order to investigate the biological responses of these glass-ceramic samples, in vitro and in vivo experiments were performed. In vitro test was performed by soaking the prepared samples in simulated body fluid (SBF) for different time intervals and then, specimens were examined by Fourier transform infrared spectroscopy. Moreover, the conversion kinetics of these samples to hydroxyapatite (HA) were determined by measuring the weight loss of glass-ceramic grains, pH values of SBF solution and recording the ionic concentrations of Si, B, P and Ca using inductive coupled plasma-atomic emission spectroscopy. The results pointed out that the prepared samples possessed fair in vitro bioactivity. However, after six weeks of implantation, the prepared glass-ceramics, on the contrary to the parent glasses, did not exhibit any bioactivity suggesting that they may need longer time. On the other hand, the crystallization process caused significant increases of microhardness and density values. From these results, we can conclude that the prepared glasses and glass-ceramics had suitable properties for bone grafts and dental applications, respectively.