Institute of Biomaterials & Biomedical Engineering, University of Toronto, Canada; Faculty of Dentistry, University of Toronto, 124 Edward St, Toronto, Canada.
Institute of Biomaterials & Biomedical Engineering, University of Toronto, Canada.
J Mech Behav Biomed Mater. 2019 Mar;91:355-365. doi: 10.1016/j.jmbbm.2018.12.025. Epub 2018 Dec 21.
Porous calcium polyphosphate (CPP) is being investigated for use as a biodegradable bone substitute and for repair of osteochondral defects. The necessary requirements for these applications, particularly in load-bearing sites, include sufficient strength to withstand functional forces prior to bone ingrowth and substitution of the initial porous CPP template with new bone and cartilage (for osteochondral implants) in a timely and efficacious manner. The present study explored the effects of Na doping and processing to form porous structures of both higher strength and faster degradation than previously reported for 'pure' (non-doped) CPP structures of similar geometry. Compressive and tensile strengths were determined before and after 30-day in vitro degradation (PBS, pH 7.1 at 37 °C) and degradation rates assessed. Scanning electron microscopy (SEM), x-ray diffraction (XRD) and solid state nuclear magnetic resonance (P SS NMR) were used to evaluate 'pure' and Na-doped CPP samples before and after degradation. The results indicated that the different processing protocols required to prepare samples of similar volume % porosity (a 2-step procedure with a Step-1 sintering temperatures equal to 575 °C being used with the Na-doped samples versus a 585 °C Step-1 treatment for 'pure' CPP) resulted in an approximate 1.5- to 2-fold increase in strength (tensile & compressive respectively) and 2-fold increase in degradation rate of Na-doped CPP compared with 'pure' CPP. This difference was attributed to the different Step-1 sintering temperatures used for sample processing.
多孔磷酸钙（CPP）作为一种可生物降解的骨替代物和修复骨软骨缺损的材料正在被研究。这些应用的必要要求，特别是在承重部位，包括在骨内生长和初始多孔 CPP 模板被新骨和软骨替代之前，具有足够的强度来承受功能力（对于骨软骨植入物），以达到及时和有效的效果。本研究探索了 Na 掺杂和形成多孔结构的效果，与以前报道的具有相似几何形状的“纯”（未掺杂）CPP 结构相比，这些多孔结构具有更高的强度和更快的降解速度。在体外降解 30 天后（PBS，37°C 时 pH7.1）测定压缩和拉伸强度，并评估降解速率。扫描电子显微镜（SEM）、X 射线衍射（XRD）和固态核磁共振（P SS NMR）用于评估降解前后的“纯”和 Na 掺杂 CPP 样品。结果表明，为了制备具有相似体积百分比孔隙率的样品，需要不同的处理方案（两步法，Na 掺杂样品的第一步烧结温度等于 575°C，而“纯”CPP 的第一步处理温度为 585°C），与“纯”CPP 相比，Na 掺杂 CPP 的强度（拉伸和压缩强度）分别增加了约 1.5-2 倍，降解速率增加了 2 倍。这种差异归因于用于样品处理的不同第一步烧结温度。
