Objective

To explore the effect of different curing modes of conventional and self-adhesive dual-cure resin cements on their rates of thermal decomposition, hardness development and network integrity.

Methods

Five self-adhesive (PANAVIA SA, RelyX Universal Resin, RelyX Unicem 2, Bifix SE and SpeedCEM Plus) and three conventional (PANAVIA V5, Nexus Third Generation and RelyX Ultimate Universal) dual-cure resin cements were investigated. Thermal decomposition stages, initial onset temperatures, the maximum rate of mass-loss and the filler mass-fraction of each resin cement were analysed by thermogravimetric analysis (TGA). Surface hardness was measured at 1 h post-cure and after 24 h of dry storage at 37 °C. The relative network integrities were estimated from reductions in hardness after 168 h of water storage. Data were analysed via one-way ANOVA, Tukey post-hoc tests and paired/independent sample t-tests ($a$ = 0.05).

Results

No difference was apparent between TGA data for self-cured and light-cured specimens. Numerical differentiation of mass-loss versus temperature showed either single or multiple peaks. For the set of 8 cements, the maximum rate of mass-loss (%/°C) correlated negatively with residual mass at 600 °C.

All dry-stored cements increased in hardness from 1 to 24 h, ranging from 20.4% to 52.6% for light-cure mode and from 41.3% to 112.6% for self-cure. After 168 h water storage, the hardness of cements decreased: by 18.5%–36.2% for light-cured and by 9.8%–17.9% for self-cured. Overall, surface hardness was greater for light-cured cements.

The initial onset temperature (IOT) of thermal decomposition correlated negatively with the hardness decrease produced by water-storage: r² = 0.77 for light-cure and r² = 0.88 for self-cure. This provided the basis for a relative scale of composite network integrity, probably reflecting differences in cross-link density.

Significance

Light-curing, where possible, remains beneficial to the hardness and related properties of dual-cure resin cements. Combination of TG analysis and solvent softening experiments give an indication of relative network integrity – between materials – and their relative cross-link densities.

中文翻译：

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固化方式对双固化树脂水门汀热稳定性、硬度发展和网络完整性的影响

客观的

探讨传统和自粘双固化树脂水泥的不同固化模式对其热分解速率、硬度发展和网络完整性的影响。

方法

研究了五种自粘剂（PANAVIA SA、RelyX Universal Resin、RelyX Unicem 2、Bifix SE 和 SpeedCEM Plus）和三种传统（PANAVIA V5、Nexus 第三代和 RelyX Ultimate Universal）双固化树脂水门汀。通过热重分析 (TGA) 分析每种树脂水泥的热分解阶段、初始起始温度、最大质量损失率和填料质量分数。在 固化后1小时和 在 37  °C下干燥储存24 小时后测量表面硬度。相对网络完整性是根据 储水168小时后硬度的降低来估计的。通过单向方差分析、Tukey事后检验和配对/独立样本 t 检验分析数据（$\mathrm{一个}$ =  0.05）。

结果

自固化和光固化样品的 TGA 数据之间没有明显差异。质量损失与温度的数值微分显示单个或多个峰。对于 8 种水泥，最大质量损失率(%/°C) 与 600  °C 时的残余质量呈负相关。

所有干贮水泥的硬度从 1 小时增加到 24小时，光固化模式从 20.4% 增加到 52.6%，自固化模式从 41.3% 增加到 112.6%。 蓄水168 h后，水泥的硬度下降：光固化水泥硬度降低18.5%–36.2%，自固化水泥硬度降低9.8%–17.9%。总的来说，光固化水泥的表面硬度更大。

热分解的初始起始温度 (IOT) 与蓄水产生的硬度降低呈负相关：r ²  =  0.77 用于光固化，r ²  =  0.88 用于自固化。这为复合网络完整性的相对规模提供了基础，可能反映了交联密度的差异。

意义

在可能的情况下，光固化仍然有利于双固化树脂粘固剂的硬度和相关性能。TG 分析和溶剂软化实验的结合表明了材料之间的相对网络完整性及其相对交联密度。