Matsuya S, Maeda T, Ohta M
Department of Dental Materials Engineering, Faculty of Dentistry, Kyushu University, Fukuoka, Japan.
J Dent Res. 1996 Dec;75(12):1920-7. doi: 10.1177/00220345960750120201.
It has been reported that the silicate phase as well as the cross-linking of the polycarboxylic acid by aluminum and calcium ions played an important role in the hardening of glass-ionomer cement. The objective of this study was to investigate the structural change during hardening of the cements by means of infrared (IR) spectroscopy and solid-state nuclear magnetic resonance (NMR) spectroscopy and to confirm the role of the silica phase in the hardening of the cement. For that purpose, we measured the change in compressive strength of an experimental glass-ionomer cement, two commercial glass-ionomer cements, and a polycarboxylate cement and carried out 29Si and 27Al NMR analyses of the cement samples after the strength measurement. In the IR spectra during hardening, a characteristic band of the silicate network around 1000 cm-1 shifted toward high frequency with time. The spectrum after hardening was similar to that for a hydrated amorphous silica structure. The 27Al NMR analysis showed that Al3+ ion was tetrahedrally coordinated by oxygen in the original glass, but a part of the Al3+ ion was octahedrally coordinated after hardening to form Al polyacrylate gel. The chemical shift of Si in the 29Si NMR spectra also changed during hardening. The variation in the chemical shift reflected the structural change in the silicate network. The initial increase in compressive strength of the cement was mainly caused by polycarboxylate gel formation. However, it was concluded that the reconstruction of the silicate network contributed to the increase in strength with time during the period after the gelation by cross-linking was completed.
据报道，硅酸盐相以及铝离子和钙离子对多元羧酸的交联在玻璃离子水门汀的硬化过程中起着重要作用。本研究的目的是通过红外（IR）光谱和固态核磁共振（NMR）光谱研究水门汀硬化过程中的结构变化，并证实二氧化硅相在水门汀硬化中的作用。为此，我们测量了一种实验性玻璃离子水门汀、两种市售玻璃离子水门汀和一种聚羧酸水门汀的抗压强度变化，并在强度测量后对水门汀样品进行了29Si和27Al NMR分析。在硬化过程的红外光谱中，1000 cm-1附近硅酸盐网络的特征带随时间向高频移动。硬化后的光谱与水合无定形二氧化硅结构的光谱相似。27Al NMR分析表明，Al3+离子在原始玻璃中由氧进行四面体配位，但部分Al3+离子在硬化后形成八面体配位以形成聚丙烯酸铝凝胶。29Si NMR光谱中Si的化学位移在硬化过程中也发生了变化。化学位移的变化反映了硅酸盐网络的结构变化。水门汀抗压强度的初始增加主要是由聚羧酸凝胶的形成引起的。然而，可以得出结论，在交联凝胶化完成后的一段时间内，硅酸盐网络的重建有助于强度随时间的增加。
