Investigating the mechanical durability of bioactive glasses as a function of structure, solubility and incubation time

• A bioactive glass series (SiO2–TiO2–CaO–Na2O/SrO) was formulated and characterized.
• Amorphous and crystalline analogues of each material were produced.
• Ion release profiles determined lower release rate for the crystalline samples.
• The pH was slightly elevated for the amorphous samples.
• Hardness values reduced over time with the amorphous samples.

This study focuses on investigating the solubility of a series of bioactive glasses that alternates the sodium (Na+) and strontium (Sr2 +) concentration. Additionally, this study investigates the effect of crystallization of these glasses and the subsequent effect on ion release, pH and mechanical strength as a function of incubation time. Ion release profiles were determined over 1, 7 and 30 days and in each case ion release was greatly reduced when the materials were crystallized. Additionally pH changes were reduced with the onset of crystallization compared to the amorphous counterparts. The most prominent changes in solubility can be attributed to the Na+ containing glasses, which presented the more soluble glasses and hence higher changes in pH. Regarding the amorphous materials, hardness was found to significantly reduce with respect to maturation; however the crystallized analogues presented much higher hardness values that did not reduce with respect to incubation time.