کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
437 | 42 | 2014 | 9 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Control of in vivo mineral bone cement degradation Control of in vivo mineral bone cement degradation](/preview/png/437.png)
The current study aimed to prevent the formation of hydroxyapatite reprecipitates in brushite-forming biocements by minimizing the availability of free Ca2+ ions in the cement matrix. This was achieved by both maximizing the degree of cement setting to avoid unreacted, calcium-rich cement raw materials which can deliver Ca2+ directly to the cement matrix after dissolution, and by a reduction in porosity to reduce Ca2+ diffusion into the set cement matrix. In addition, a biocement based on the formation of the magnesium phosphate mineral struvite (MgNH4PO4·6H2O) was tested, which should prevent the formation of low-solubility hydroxyapatite reprecipitates due to the high magnesium content. Different porosity levels were fabricated by altering the powder-to-liquid ratio at which the cements were mixed and the materials were implanted into mechanically unloaded femoral defects in sheep for up to 10 months. While the higher-porosity brushite cement quantitatively transformed into crystalline octacalcium phosphate after 10 months, slowing down cement resorption, a lower-porosity brushite cement modification was found to be chemically stable with the absence of reprecipitate formation and minor cement resorption from the implant surface. In contrast, struvite-forming cements were much more degradable due to the absence of mineral reprecipitates and a nearly quantitative cement degradation was found after 10 months of implantation.
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Journal: Acta Biomaterialia - Volume 10, Issue 7, July 2014, Pages 3279–3287