Investigating the influence of Na super(+) and Sr super(2+) on the structure and solubility of SiO sub(2)-TiO sub(2)-CaO-Na sub(2)O/SrO bioactive glass

This study was conducted to determine the influence that network modifiers, sodium (Na super(+)) and strontium (Sr super(2+)), have on the solubility of a SiO sub(2)-TiO sub(2)-CaO-Na sub(2)O/SrO bioactive glass. Glass characterization determined each composition had a similar structure, i.e. bridging to non-bridging oxygen ratio determined by X-ray photoelectron spectroscopy. Magic angle spinning nuclear magnetic resonance (MAS-NMR) confirmed structural similarities as each glass presented spectral shifts between -84 and -85 ppm. Differential thermal analysis and hardness testing revealed higher glass transition temperatures (T sub(g) 591-760 degree C) and hardness values (2.4-6.1 GPa) for the Sr super(2+) containing glasses. Additionally the Sr super(2+) (~250 mg/L) containing glasses displayed much lower ion release rates than the Na super(+) (~1,200 mg/L) containing glass analogues. With the reduction in ion release there was an associated reduction in solution pH. Cytotoxicity and cell adhesion studies were conducted using MC3T3 Osteoblasts. Each glass did not significantly reduce cell numbers and osteoblasts were found to adhere to each glass surface.