School of Dentistry, Universidade Positivo, Brazil.
School of Dental Medicine, University of Pennsylvania, USA.
Dent Mater. 2024 Nov;40(11):1862-1871. doi: 10.1016/j.dental.2024.08.004. Epub 2024 Aug 28.
To assess the impact of elastic gradients formed among restorative material, cement, and substrate on the fracture resistance of tri-layer restorative systems.
Four CAD/CAM materials were utilized, two glass-ceramics (IPS e.max CAD, Vita Suprinity) and two resin-ceramic hybrids (Vita Enamic, Lava Ultimate). Their fracture resistance was examined by biaxial flexure (n = 8) and Hertzian indentation (n = 10) tests. Statistical analysis was conducted using ANOVA and Tukey tests (p = 5 %). Finite element analysis (FEA) was employed to simulate the Hertzian indentation test and elucidate the stress-fields formed on the intaglio surface below the loading area.
The biaxial flexural strength (MPa) of glass-ceramics exceeded the hybrid materials (e.max 417, Suprinity 230, Enamic 138, and Lava Ultimate 183). Conversely, the load-bearing capacity (N) of the materials bonded to dentin analog demonstrated the opposite trend, with the hybrid materials achieving superior results (e.max 830 , Suprinity 660, Enamic 1822, and Lava Ultimate 2593 ). The stress-fields observed by FEA were coherent with the experimental results for Hertzian flexural stresses (MPa): e.max 501 , Suprinity 342 , Enamic 406, whereas no tensile stress was observed at the intaglio surface of Lava Ultimate.
Detailed analysis of the fracture resistance of the tri-layer restorative systems showed that the elastic gradients play a more significant role than the flexural strength of the restorative materials. The coherence of the elastic moduli between the restorative material and supporting structures results in reduced tensile stress concentration at the intaglio surface beneath the loading area and enhances the ability to withstand load.
评估修复材料、粘结剂和基底层之间形成的弹性梯度对三层修复系统抗断裂能力的影响。
使用了四种 CAD/CAM 材料，两种玻璃陶瓷（IPS e.max CAD、Vita Suprinity）和两种树脂陶瓷混合材料（Vita Enamic、Lava Ultimate）。通过双向弯曲（n=8）和赫兹压痕（n=10）试验检测它们的抗断裂能力。采用方差分析和 Tukey 检验（p=5%）进行统计学分析。采用有限元分析（FEA）模拟赫兹压痕试验，阐明加载区域下方凹印面形成的应力场。
玻璃陶瓷的双向弯曲强度（MPa）超过了混合材料（e.max 417、Suprinity 230、Enamic 138 和 Lava Ultimate 183）。相反，粘结到牙本质模拟体的材料的承载能力（N）则呈现相反的趋势，混合材料表现出更好的结果（e.max 830、Suprinity 660、Enamic 1822 和 Lava Ultimate 2593）。FEA 观察到的应力场与赫兹弯曲应力的实验结果（MPa）一致：e.max 501、Suprinity 342、Enamic 406，而在 Lava Ultimate 的凹印面没有观察到拉伸应力。
对三层修复系统抗断裂能力的详细分析表明，弹性梯度比修复材料的弯曲强度起着更重要的作用。修复材料和支撑结构之间弹性模量的协调性导致在加载区域下方的凹印面处减少了拉伸应力集中，并增强了承受负荷的能力。
