Studies of the early stages of the dynamic setting process of chemically activated restorative glass-ionomer cements

To evaluate the early stages of the setting process of chemically activated restorative glass-ionomer cements (GICs). Five GICs were evaluated (<i>n</i> = 5): Equia Forte (GC), Equia Forte HT (GC), Ketac Universal (3M ESPE), Maxxion R (FGM) and Riva Self Cure (SDI) by Thermography, Fourier Transform Infrared Attenuated Total Reflectance Spectroscopy (FTIR-ATR) and Gillmore needle indentation mechanical testing. The FTIR-ATR spectra showed the formation of metal carboxylates within the cements and enabled the stabilization time (ST) to be determined and the thermographic camera measured the temperature field images in the sample. Data were statistically analyzed by ANOVA and Tukey–Kramer (<i>α</i> = 5%). The Gillmore needle test showed that the order of hardening was opposite to the order of ST values determined by FTIR. The results with the thermographic camera showed two stages of temperature variation, which coincided with the evolution of specific infrared bands. The exception was Maxxion R, which showed only a single step change in temperature. The early stages of the GIC setting reaction show temperature changes, both endothermic and exothermic, at specific times, confirming the occurrence of individual chemical reactions. The early setting involves reactions other than carboxylate formation. <b>Significance</b>: This study gives further detail of the early stages of the setting of GICs, and past research regarding the setting reaction of GIC.

本研究旨在评估化学活化修复用玻璃离子水门汀（glass-ionomer cements, GICs）的固化早期进程。本研究共评估了5款玻璃离子水门汀，每组样本量n=5：Equia Forte（GC）、Equia Forte HT（GC）、Ketac Universal（3M ESPE）、Maxxion R（FGM）以及Riva Self Cure（SDI），测试方法包括热成像法（Thermography）、傅里叶变换红外衰减全反射光谱法（FTIR-ATR）以及吉尔摩针压痕力学测试。FTIR-ATR光谱可检测到水门汀内部金属羧酸盐的生成，并可确定其固化稳定时间（ST）；热成像相机则可采集样品的温度场图像。所有数据均采用方差分析（ANOVA）与图基-克莱默检验（Tukey–Kramer）进行统计学分析，显著性水平设定为α=5%。吉尔摩针测试结果显示，水门汀的固化速率顺序与FTIR测得的固化稳定时间顺序恰好相反。热成像检测结果显示样品存在两个温度变化阶段，该结果与特定红外波段的演化趋势相契合；唯有Maxxion R仅表现出单次温度阶跃变化。玻璃离子水门汀的固化早期阶段会在特定时间点出现吸热与放热的温度变化，这证实了单个独立化学反应的发生；固化早期过程不仅包含羧酸盐生成反应，还涉及其他反应类型。**研究意义**：本研究进一步阐明了玻璃离子水门汀的固化早期进程，补充了现有关于该类水门汀固化反应的相关研究成果。