The Morphology and Conversion of Bone Cement and Borate Bioactive Glass Composites into Magnesium- Substituted Hydroxyapatite

摘要

The morphology of the precipitates and the solution pH were dependent upon the glass particle size and the amount of glass loading in the composites. Elemental mapping suggested that the precipitate was hydroxyapatite due to the presence of oxygen alongside calcium and phosphate. The precipitate also contained magnesium. Substituting calcium with magnesium causes changes to the bond lengths and the matrix structure of hydroxyapatite, as magnesium ions are smaller than calcium ions, and this partial substitution increases the disorder of the crystallinity of the hydroxyapatite. In micro-Raman spectroscopy, a decrease in crystallinity lowers the intensity of PO_4~(3-) spectra and increases the peak width. Because the peak at 964 cm"1 would decrease in intensity as the amount of magnesium rose, it is possible that the precipitate incorporated more magnesium over time, as seen in 40% 100 μm, and that 5 μm samples, which showed less evident peaks, incorporated more magnesium than 100 μm samples did. Future work performed in vivo would better simulate the human body's environment, and the effect of solution pH upon precipitate morphology could be further studied. This is the first work to incorporate 13-93B3 glass into PMMA-based bone cement and study the resulting surface precipitate. Characterizing the formation of this precipitate can help predict the ability of the cement composites to promote bone attachment and thus further stabilize orthopedic implants.