Institute of Science and Technology, Univ Estadual Paulista - Unesp, São José dos Campos., São Paulo, Brazil.
Federal University of Juiz de Fora (UFJF), School of Dentistry, Minas Gerais, Brazil.
J Mech Behav Biomed Mater. 2019 Jun;94:207-212. doi: 10.1016/j.jmbbm.2019.03.011. Epub 2019 Mar 15.
This study evaluated the effect of different loading pistons, made of various materials and with different elastic moduli acting as antagonist material, on stress distribution and fatigue behavior of a CAD/CAM silica-based ceramic.
Discs of CAD/CAM made silica-based ceramic (N = 60) (VITA MARK II) were divided into six groups (n = 10 per group), according to the test method (M: Monotonic; F: Fatigue) and the antagonist piston material (T: Tungsten; S: Steel; G: Epoxy resin). FT, FS and FG combinations were submitted to mechanical cycling (2 × 10 cycles, 4 Hz, 45 N). The bending stress after fatigue were also valuated using Weibull analysis and the parameters η (eta), β (beta) and the mean time to failure (MTTF) were calculated. Fractographic analysis and Finite Element Analysis (FEA) were performed. Data were analyzed using ANOVA and Tukey's tests (alpha=0.05).
MG presented significantly less bending strength (MPa) (75.6) compared to MT (87.8) and MS (84.4) (p < 0.05). Six specimens from FT (MMTF: 8.3 × 10; β:0.60; η:5.6 × 10), four from FS (MMTF: 1.9 × 10; β:1.2; η:2.0 × 10) and one from FG (MMTF: 1.3 × 10; β:0.48; η:0.64 × 10) survived the fatigue test. The stress peak on the tensile surface of S was similar to that of T and both were less than that of G. The failure origins were on the tensile surface.
The epoxy resin pistons were able to decrease the bending stress, and life expectancy (faster failure) of a silica-based ceramic compared to tungsten and steel.
本研究评估了作为拮抗材料的不同材料和不同弹性模量的加载活塞对 CAD/CAM 硅基陶瓷的应力分布和疲劳行为的影响。
根据测试方法（M：单调；F：疲劳）和拮抗活塞材料（T：钨；S：钢；G：环氧树脂）将 60 个 CAD/CAM 硅基陶瓷（VITA MARK II）制成的圆盘分为六组（每组 10 个）。FT、FS 和 FG 组合进行机械循环（2×10 次循环，4Hz，45N）。疲劳后还评估了弯曲应力，使用威布尔分析计算了参数 η（eta）、β（beta）和平均失效时间（MTTF）。进行了断口分析和有限元分析（FEA）。使用方差分析和 Tukey 检验（alpha=0.05）分析数据。
MG 的弯曲强度（MPa）（75.6）明显低于 MT（87.8）和 MS（84.4）（p<0.05）。FT 有 6 个样本（MMTF：8.3×10；β：0.60；η：5.6×10）、FS 有 4 个样本（MMTF：1.9×10；β：1.2；η：2.0×10）和 FG 有 1 个样本（MMTF：1.3×10；β：0.48；η：0.64×10）在疲劳试验中存活。S 的拉伸表面的应力峰值与 T 相似，均小于 G。失效起源于拉伸表面。
与钨和钢相比，环氧树脂活塞能够降低硅基陶瓷的弯曲应力和预期寿命（更快失效）。
