The physics of water sorption by resin-modified glass-ionomer dental cements
The physics of water sorption by resin-modified glass-ionomer dental cements
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树脂改性玻璃离聚物牙科粘固剂吸水的物理原理
DOI：
10.1023/a:1018587907243
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
J. Nicholson
中科院分区：
文献类型：
--
作者：
J. Nicholson
研究了两种市售树脂改性玻璃离子牙科粘固剂（基线VLC，ex. Detrey Dentsply和Vitremer内衬水泥，例如3 M牙科产品）进行了比以前更详细的研究。两种水泥中的水吸附被证明是快速的，基线VLC在约48小时达到平衡，Vitremer在约10天达到平衡。在最初的8小时左右，吸收符合菲克定律，基线VLC（固化20 s）的扩散系数为1.56×10-7 cm 2 s-1，Vitremer（也固化20 s）为5.09×10-7 cm 2 s-1。正如预期的那样，发现在固化时间较短的样品中水的吸附更快，而在固化时间较长的样品中水的吸附更慢。在存在氯化钠的情况下，无论是0.9%还是1 M，扩散系数均显著大于纯水中的扩散系数，但不随氯化钠浓度而显著变化，基线VLC的扩散系数约为3.3×10-7 cm 2 s-1，Vitremer的扩散系数约为8.0×10-7 cm 2 s-1。这是由于吸收氯化钠水溶液时聚合物亲水性链段的构象变化，其中分子形成比纯水存在下更紧凑的线圈。因此，它们产生了一种更容易透水的微观结构。在盐溶液中的吸附成为非菲克比在纯水中快得多，即在3-4小时的两种水泥。这可能是由于水泥中盐的浓度变化，表明这些材料具有一定程度的渗透选择性。最后，平衡吸水量随盐浓度而变化，在1 M NaCl中最小，这反映了不同储存介质中水的不同化学势。
The water-sorption characteristics of two commercial resin-modified glass-ionomer dental cements (Baseline VLC, ex. Detrey Dentsply, and Vitremer lining cement, ex. 3M Dental Products) have been studied in more detail than previously. Water sorption in both cements proved to be rapid, reaching equilibrium at approximately 48 h for Baseline VLC and at approximately 10 d for Vitremer. Over the first 8 h or so, absorption was shown to follow Fick’s law, with a diffusion coefficient of 1.56×10-7 cm2 s-1 for Baseline VLC (cured for 20 s) and 5.09×10-7 cm2 s-1 for Vitremer (also cured for 20 s). As expected, sorption of water was found to be faster in specimens cured for shorter cure times and slower for those cured for longer times. In the presence of sodium chloride, both at 0.9% and at 1 M, diffusion coefficients were significantly greater than in pure water, but did not vary significantly with sodium chloride concentration, being approximately 3.3×10-7 cm2 s-1 for Baseline VLC and 8.0×10-7 cm2 s-1 for Vitremer. This is attributed to conformational changes in hydrophilic segments of the polymer on absorption of aqueous sodium chloride in which the molecules form more compact coils than in the presence of pure water. They thus create a microstructure that is more permeable to water. Sorption in salt solutions became non-Fickian much sooner than in pure water, i.e. at 3–4 h for both cements. This is probably due to concentration changes of salt within the cement, suggesting that these materials possess a degree of permselectivity. Finally, equilibrium water uptakes varied with salt concentration, being least in 1 M NaCl, which reflects the different chemical potentials of water in the various storage media.