Arcila Laura Viviana Calvache, Gomes Laís Carolina Landim, Ortiz Laura Patricia Nadal, Costa Mardoqueu M da, Tribst João Paulo Mendes, Bottino Marco Antonio, Saavedra Guilherme de Siqueira Ferreira Anzaloni, de Melo Renata Marques
Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University (Unesp), São José dos Campos, Brazil.
Department of Dentistry, Brasil University, São Paulo, Brazil.
Eur J Dent. 2023 Oct;17(4):1316-1324. doi: 10.1055/s-0042-1758797. Epub 2022 Dec 19.
This study was performed to evaluate fatigue survival by shear test in the union of leucite-reinforced feldspathic ceramic using different cement thicknesses.
Leucite-reinforced glass ceramics blocks were sectioned in 2-mm thick slices where resin cylinders were cemented. The samples were distributed in two experimental groups ( = 20) according to the cement thickness (60 and 300 μm). The specimens of each group were submitted to the stepwise fatigue test in the mechanical cycling machine under shear stress state, with a frequency of 2 Hz, a step-size of 0.16 bar, starting with a load of 31 N (1.0 bar) and a lifetime of 20,000 cycles at each load step.
The samples were analyzed in a stereomicroscope and scanning electron microscopy to determine the failure type. There is no significant difference between the mean values of shear bond strength according to both groups. Log-rank ( = 0.925) and Wilcoxon ( = 0.520) tests revealed a similar survival probability in both cement layer thicknesses according to the confidence interval (95%). The fracture analysis showed that the mixed failure was the most common failure type in the 300-μm thickness group (80%), while adhesive failure was predominant in the 60-μm thickness group (67%). The different cement thicknesses did not influence the leucite ceramic bonding in fatigue shear testing; however, the thicker cement layer increased the predominance of the ceramic material failure.
The resin cement thicknesses bonded to leucite ceramic did not influence the long-term interfacial shear bond strength, although thicker cement layer increased the ceramic material cohesive failure. Regardless the cement layer thickness, the shear bond strength lifetime decreases under fatigue.
本研究旨在通过剪切试验评估不同水泥厚度下白榴石增强长石质陶瓷结合处的疲劳寿命。
将白榴石增强玻璃陶瓷块切成2毫米厚的薄片，在其上粘结树脂圆柱体。根据水泥厚度（60和300μm）将样品分为两个实验组（每组n = 20）。每组试样在机械循环试验机中于剪切应力状态下进行逐步疲劳试验，频率为2Hz，步长为0.16bar，起始载荷为31N（1.0bar），每个载荷步的寿命为20000次循环。
在立体显微镜和扫描电子显微镜下分析样品以确定失效类型。两组之间的剪切粘结强度平均值无显著差异。对数秩检验（P = 0.925）和威尔科克森检验（P = 0.520）显示，根据95%置信区间，两种水泥层厚度的存活概率相似。断裂分析表明，混合失效是300μm厚度组中最常见的失效类型（80%），而粘结失效在60μm厚度组中占主导（67%）。不同的水泥厚度在疲劳剪切试验中不影响白榴石陶瓷的粘结；然而，较厚的水泥层增加了陶瓷材料失效的占比。
粘结到白榴石陶瓷上的树脂水泥厚度不影响长期界面剪切粘结强度，尽管较厚的水泥层增加了陶瓷材料的内聚失效。无论水泥层厚度如何，在疲劳作用下剪切粘结强度寿命都会降低。
