Wang Kun, Peng Qingyue, Yao Jiaqi, Wang Zhengzhi
Department of Engineering Mechanics, School of Civil Engineering, Wuhan University, Wuhan, Hubei 430072, China.
Department of Engineering Mechanics, School of Civil Engineering, Wuhan University, Wuhan, Hubei 430072, China; Wuhan University Shenzhen Research Institute, Shenzhen 518108, China.
Dent Mater. 2025 Mar;41(3):319-330. doi: 10.1016/j.dental.2024.12.005. Epub 2025 Jan 2.
Photopolymerized resin composites are widely used as dental filling materials. However, the shrinkage stress generated during photopolymerization can lead to marginal microcracks and eventual restoration failure. Accurate assessment of the stress evolution in dental restorations, particularly in complex cavity geometries, is critical for improving the performance and longevity of the dental filling materials. This study aims to develop a novel mechano-chemo-thermo-coupled finite element method (FEM) to accurately capture three-dimensional (3D) shrinkage stress of resin-based photopolymerized filling materials.
The FEM was established with consideration for the evolution of mechanical properties, thermal effects, and polymerization shrinkage during photopolymerization. Real-time material property evolution was derived from measurements of degree of conversion and temperature changes, and these were integrated into the FEM alongside thermal expansion/contraction effects. The FEM was parameterized through mechanical, chemical, and thermal experiments, then applied to simulate different photocuring protocols and boundary conditions. The accuracy of the predicted shrinkage stress was validated through three experiments: uniaxial shrinkage stress measurement, full-field optical measurement, and acoustic emission analysis using typical dimethacrylate-based dental filling materials.
The coupled FEM model achieved predictive stress magnitudes in quantitative agreement with the experimental measurements (relative error ∼1 %), significantly improving upon existing methods (∼22.5 %). Furthermore, the FEM accurately predicted spatial debonding based on stress distribution, providing insights unattainable through current methods.
This experiment-modeling-combined study provides a valuable tool for accurately predicting the spatial and temporal evolution of the shrinkage stress in resin-based dental filling materials, thereby providing new insights for optimizing their clinical applications and enhancing durability.
光聚合树脂复合材料被广泛用作牙科填充材料。然而，光聚合过程中产生的收缩应力会导致边缘微裂纹并最终导致修复失败。准确评估牙科修复体中的应力演变，尤其是在复杂的窝洞几何形状中，对于提高牙科填充材料的性能和使用寿命至关重要。本研究旨在开发一种新型的机械 - 化学 - 热耦合有限元方法（FEM），以准确捕捉基于树脂的光聚合填充材料的三维（3D）收缩应力。
建立有限元模型时考虑了光聚合过程中机械性能、热效应和聚合收缩的演变。通过转化率和温度变化的测量得出实时材料性能演变，并将其与热膨胀/收缩效应一起整合到有限元模型中。通过机械、化学和热实验对有限元模型进行参数化，然后应用于模拟不同的光固化方案和边界条件。使用典型的基于二甲基丙烯酸酯的牙科填充材料，通过单轴收缩应力测量、全场光学测量和声发射分析这三个实验验证预测收缩应力的准确性。
耦合有限元模型实现的预测应力大小与实验测量值在数量上一致（相对误差约为1%），相比现有方法（约22.5%）有显著改进。此外，有限元模型根据应力分布准确预测了空间脱粘情况，提供了现有方法无法获得的见解。
本实验 - 建模相结合的研究为准确预测基于树脂的牙科填充材料收缩应力的时空演变提供了一个有价值的工具，从而为优化其临床应用和提高耐久性提供了新的见解。
