Ishikawa K, Asaoka K
Department of Dental Engineering, School of Dentistry, Tokushima University, Japan.
J Biomed Mater Res. 1995 Dec;29(12):1537-43. doi: 10.1002/jbm.820291210.
The ideal mechanical strength and critical porosity of calcium phosphate cement (CPC) were estimated to help determine ways to improve its properties. CPC at various porosities was made by packing CPC paste, at various powder-to-liquid (P/L) ratios (2.0-6.0), into a mold under various pressures (0-173 MPa). The mechanical strength of CPC, in terms of diametral tensile strength (DTS), increased with decreases in porosity. Intercrystalline fracture was observed in specimens made without the application of pressure, while fracture within the crystals increased with the packing pressure. These observations support the application of the relationship between DTS and porosity in fractographic equations. The ideal wet DTS and critical porosity of CPC were estimated to be 102 MPa and 63%, respectively. The minimum porosity of the currently used CPC was approximately 26-28%, even when it was packed under 173 MPa, and the maximum DTS value was thus approximately 13-14 MPa. Because reducing the porosity of currently used CPC would be difficult, we conclude that in CPC-related research, we should focus on ways in which to accelerate bone-replacing behavior, in addition to improving the mechanical strength of CPC.
估算磷酸钙骨水泥（CPC）的理想机械强度和临界孔隙率，以帮助确定改善其性能的方法。通过将不同粉液比（2.0 - 6.0）的CPC糊剂在不同压力（0 - 173 MPa）下填充到模具中，制备出具有不同孔隙率的CPC。以径向拉伸强度（DTS）衡量，CPC的机械强度随孔隙率降低而增加。在未施加压力制备的试样中观察到晶间断裂，而晶体内部的断裂随填充压力增加。这些观察结果支持在断口分析方程中应用DTS与孔隙率之间的关系。CPC的理想湿态DTS和临界孔隙率估计分别为102 MPa和63%。即使在173 MPa压力下填充，目前使用的CPC的最小孔隙率约为26 - 28%，因此最大DTS值约为13 - 14 MPa。由于降低目前使用的CPC的孔隙率很困难，我们得出结论，在与CPC相关的研究中，除了提高CPC的机械强度外，我们还应关注加速骨替代行为的方法。
