Objective

This study evaluated the properties of experimental dual-cured cements containing thiourethane (TU) and low concentrations of p-Tolyldiethanolamnie (DHEPT) and benzoyl peroxide (BPO) as chemical initiators.

Methods

BisGMA/TEGDMA-based dual-cured cement was formulated with 1.0 wt% DHEPT and 0.75 wt% BPO as initiators and used as control. The concentration of BPO was adjusted to 0.1 wt% in catalyst paste of experimental cements, and two base pastes containing TU and 0.5 wt% or 0.25 wt% of DHEPT were formulated. The rheological behavior and kinetics of polymerization of cements were assessed in the absence of light activation. The kinetics of polymerization was also evaluated for cements light-activated immediately or 5 min after the start of mixing. Polymerization stress, flexural strength and elastic modulus (n = 5) were also evaluated under these conditions.

Results

Cements with TU presented lower viscosity than the control, improved working time (0.25% DHEPT > 0.5% DHEPT) and higher conversion in the absence of light-activation. Delaying the light-activation reduced the maximum rate of polymerization (Rp_max) but did not affect the conversion or stress. The addition of TU increased the Rp_max and conversion, and reduced the stress when compared to the control, without affecting the flexural strength. Except for the control with delayed light-activation (highest values), the other experimental conditions yielded similar modulus.

Significance

Adding TU and using a low concentration of DHEPT/BPO resulted in dual-cured cements with longer working time, reduced polymerization stress and increased conversion even in the absence of light, with no significant effect on the mechanical properties.

中文翻译：

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开发具有长工作时间、高转化率和低聚合应力的双固化树脂粘固剂。

客观的

本研究评估了含有硫代氨基甲酸酯 (TU) 和低浓度对甲苯基二乙醇胺 (DHEPT) 和过氧化苯甲酰 (BPO) 作为化学引发剂的实验性双固化水泥的性能。

方法

基于 BisGMA/TEGDMA 的双固化水泥用 1.0 wt% DHEPT 和 0.75 wt% BPO 作为引发剂配制并用作对照。在实验水泥的催化剂糊中，BPO 的浓度调整为 0.1 wt%，并配制了两种含有 TU 和 0.5 wt% 或 0.25 wt% DHEPT 的基糊。在没有光活化的情况下评估了水泥聚合的流变行为和动力学。还评估了在混合开始后立即或 5 分钟光活化的水泥的聚合动力学。在这些条件下还评估了聚合应力、弯曲强度和弹性模量 (n = 5)。

结果

具有 TU 的水泥表现出比对照物更低的粘度、改进的工作时间（0.25% DHEPT > 0.5% DHEPT）和在没有光活化的情况下更高的转化率。延迟光活化会降低最大聚合速率 (Rp _max )，但不会影响转化率或应力。与对照相比，TU 的添加增加了 Rp _max和转化率，并降低了应力，而不会影响抗弯强度。除了具有延迟光激活的对照（最高值）外，其他实验条件产生了相似的模量。

意义

添加 TU 并使用低浓度的 DHEPT/BPO 导致双固化水泥具有更长的工作时间，即使在没有光照的情况下也能降低聚合应力并提高转化率，而对力学性能没有显着影响。