Comprehensive Study on Color Changes of Glass-ionomer Cement Family Dental Materials

玻璃离子水门汀的颜色变化具有时间依赖性。然而，关于玻璃离子水门汀颜色变化机理的研究报道较少。本研究的目的是探讨玻璃离子水门汀与颜色变化有关的物理化学变化。本研究的时间分为3组：1小时、1个月和1年。在一小时内，颜色变化与流变仪的振幅值之间没有相关性。然后，从CIEIAB系统的值计算每分钟之间的色差变化量。本研究提示了色差变化量与振幅值之间存在相关性的可能性。玻璃离子水门汀在一个月内的颜色变化与吸水量的变化有很高的相关性。从一个月到一年，颜色几乎没有变化，水泥的吸水量也几乎没有变化。然而，似乎必须经过大约6个月才能使颜色稳定，虽然用于对比的树脂改性玻璃离子水门汀在1个月内显示出轻微的颜色变化，但1年内几乎没有颜色变化。然而，树脂改性的玻璃离子水门汀的吸水量大于本研究中使用的其他材料，1年的吸水量约为5%（重量比）。在树脂改性玻璃离子水门汀的情况下，颜色变化和吸水量之间没有相关性。在作为对照的复合树脂中，颜色变化和吸水量小于玻璃离子水门汀。

The color change of the glass ionomer cement Is time-dependent. However, there were few research reported the mechanism of the color change of the glass ionomer cement. The purpose of this study was to Investigate the physicochemical changes of glass ionomer cement concerning color change. The period of this study was divided into 3 groups; an hour, a month and a year. There was no relevance between the color change and the value of amplitude by means of rheometer in an hour. Then, the amount of change of color difference between every minute was calculated from the values of CIEIAB system. This study indicated the possibility of the relevance between amount of change of color difference and value of the amplitude. There was the high correlation between color change and change of amount of water sorption of the glass ionomer cement in a month. There was hardly the color change In a year from a month, also there was hardly the change of amount of water sorption of the cement. However, it seemed to have to pass through over about 6 months to become stable of the color.Though the resin modified glass ionomer cement used for the comparison showed the slight color change during 1 month, there was hardly the color change for 1 year. However, amount of water sorption of the resin modified glass ionomer cement was larger than other materials used in this study, and It was about 5% as a weight ratio for 1 year. In case of the resin modified glass ionomer cement, there was no relevance between color change and amount of water sorption. In the composite resin used as a control, the color change and the amount of water sorption were smaller than glass ionomer cement.