Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
J Biomed Mater Res A. 2012 May;100(5):1293-306. doi: 10.1002/jbm.a.34018. Epub 2012 Feb 28.
The local structural changes in amorphous calcium phosphate (ACP)-based dental composites were studied under isothermal conditions using both static, bulk measurement techniques and a recently developed methodology based on combined ultra-small angle X-ray scattering-X-ray photon correlation spectroscopy (USAXS-XPCS), which permits a dynamic approach. While results from conventional bulk measurements do not show clear signs of structural change, USAXS-XPCS results reveal unambiguous evidence for local structural variations on a similar time scale to that of water loss in the ACP fillers. A thermal-expansion-based simulation indicates that thermal behavior alone does not account for the observed dynamics. Together, these results suggest that changes in the water content of ACP affect the composite morphology due to changes in ACP structure that occur without an amorphous-to-crystalline conversion. It is also noted that biomedical materials research could benefit greatly from USAXS-XPCS, a dynamic approach.
采用静态、整体测量技术以及最近基于组合超小角 X 射线散射- X 射线光子相关光谱学（USAXS-XPCS）的方法研究了无定形磷酸钙（ACP）基牙科复合材料在等温条件下的局部结构变化，该方法允许采用动态方法。虽然常规整体测量结果没有显示出结构变化的明显迹象，但 USAXS-XPCS 结果明确证明了与 ACP 填料中水分损失相似时间尺度上的局部结构变化。基于热膨胀的模拟表明，仅热行为不能解释所观察到的动力学。这些结果表明，ACP 含水量的变化会由于 ACP 结构发生变化而影响复合材料的形态，而这种变化不会发生无定形到结晶的转化。还注意到，生物医学材料研究将从 USAXS-XPCS 中受益匪浅，这是一种动态方法。
