Department of Dentistry, Federal University of Sergipe, Rua Claudio Batista s/n, 49060-100, Aracaju, SE, Brazil.
Department of Restorative Dentistry, Division of Biomaterials and Biomechanics, Oregon Health & Science University, 2730 SW Moody Ave, 97201, Portland, OR, USA.
Dent Mater. 2020 Oct;36(10):e293-e301. doi: 10.1016/j.dental.2020.06.005. Epub 2020 Jul 4.
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.
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.
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) but did not affect the conversion or stress. The addition of TU increased the Rp 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.
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.
本研究评估了含有硫代尿嘧啶（TU）和低浓度对甲苯二乙醇胺（DHEPT）和过氧化苯甲酰（BPO）的实验性双重固化水泥的性能，这些物质作为化学引发剂。
基于 BisGMA/TEGDMA 的双重固化水泥以 1.0wt% DHEPT 和 0.75wt% BPO 作为引发剂进行配方设计，并用作对照。在实验性水泥的催化剂糊剂中，将 BPO 的浓度调整至 0.1wt%，并配制了两种含有 TU 和 0.5wt%或 0.25wt% DHEPT 的基础糊剂。评估了在没有光激活的情况下水泥的聚合流变性和动力学。还评估了在混合开始后立即或 5 分钟后用光激活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）。
含有 TU 的水泥的粘度低于对照物，在没有光激活的情况下，工作时间（0.25%DHEPT＞0.5%DHEPT）得到改善，转化率提高。延迟光激活降低了最大聚合速率（Rp），但不影响转化率或应力。与对照物相比，TU 的添加增加了 Rp 和转化率，降低了应力，而对弯曲强度没有影响。除了延迟光激活的对照物（具有最高值）之外，其他实验条件得出的模量相似。
添加 TU 并使用低浓度的 DHEPT/BPO 可得到工作时间更长、聚合应力降低、转化率提高的双重固化水泥，即使在没有光的情况下也能达到，而对机械性能没有显著影响。
