Objectives

The aim of this study was to modify the surface of fillers used in dental composites by the synthesis of two novel thiourethane oligomeric silanes, used to functionalize the silica-containing inorganic particles. Several thiourethane silane concentrations were tested during the silanization process to systematically assess the effect of silane coverage on experimental composite conversion, polymerization stress and fracture toughness. Materials and Methods

Two different thiourethane silanes were synthesized based either on 1,6-hexanediol-diissocynate (HDDI), or 1,3-bis(1-isocyanato-1-methylethyl) benzene (BDI). Conventional 3-(Trimethoxysilyl)propyl methacrylate was used as the control. Glass fillers were silanized with 1, 2 or 4 wt% of each thiourethane silane, then evaluated by thermogravimetrical analysis. Photopolymerizable resin composites were prepared with Bis-GMA/UDMA/TEGDMA and 50 wt% silanized glass filler. Polymerization kinetics and degree of conversion were tested using Near-IR. Bioman was used to test polymerization stress. Data were analyzed with two-way ANOVA/Tukey’s test (α=5%).

Results

The mass of silane coupled to the filler increased with the concentrations of thiourethane in the silanizing solution, as expected. Thiourethane-containing groups exhibited significantly higher degree of conversion compared to control groups, except for BDI 4%. HDDI 4%, BDI 2% and BDI 4% showed significantly lower polymerization stress than control groups. HDDI 4% exhibited significantly higher fracture toughness.

Conclusions and Clinical significance

Novel filler functionalization with thiourethane silanes may be a promising alternative for improving dental composites properties by significantly increasing the degree of conversion, fracture toughness and reducing the polymerization stress.

中文翻译：

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牙科树脂复合材料的硫代氨基甲酸酯填料功能化：对增韧、应力降低和固化深度的浓度依赖性影响

 目标

本研究的目的是通过合成两种新型硫代氨基甲酸酯低聚硅烷来改性牙科复合材料中使用的填料的表面，用于功能化含二氧化硅的无机颗粒。在硅烷化过程中测试了几种硫代氨基甲酸酯硅烷浓度，以系统评估硅烷覆盖率对实验复合材料转化率、聚合应力和断裂韧性的影响。材料和方法

基于 1,6-己二醇二异氰酸酯 (HDDI) 或 1,3-双(1-异氰酸酯基-1-甲基乙基)苯 (BDI) 合成了两种不同的硫代氨基甲酸酯硅烷。使用常规的甲基丙烯酸3-(三甲氧基甲硅烷基)丙酯作为对照。玻璃填料用 1、2 或 4 wt% 的每种硫代氨基甲酸酯硅烷进行硅烷化，然后通过热重分析进行评估。用 Bis-GMA/UDMA/TEGDMA 和 50 wt% 硅烷化玻璃填料制备光聚合树脂复合材料。使用近红外测试聚合动力学和转化度。 Bioman 用于测试聚合应力。使用双向方差分析/Tukey 检验（α=5%）对数据进行分析。

 结果

正如预期的那样，与填料偶联的硅烷的质量随着硅烷化溶液中硫代氨基甲酸酯的浓度而增加。与对照组相比，含硫代氨基甲酸酯的基团表现出显着更高的转化程度，但 BDI 4% 除外。 HDDI 4%、BDI 2% 和 BDI 4% 的聚合应力显着低于对照组。 HDDI 4%表现出显着更高的断裂韧性。

结论及临床意义

使用硫氨酯硅烷进行新型填料官能化可能是一种有前景的替代方案，可通过显着提高转化率、断裂韧性和降低聚合应力来改善牙科复合材料的性能。