Division of Restorative and Esthetic Dentistry, School of Dentistry and Graduate Institute of Clinical Dentistry, National Taiwan University and National Taiwan University Hospital, 1, Chang-de St., Taipei 100, Taiwan.
Department of Mechanical Engineering, National Taipei University of Technology, 1, Sec. 3 Chung-Hsiao E. Rd., Taipei 106, Taiwan; Additive Manufacturing Center for Mass Customization Production, National Taipei University of Technology, Taipei 106, Taiwan.
Acta Biomater. 2019 Apr 15;89:382-390. doi: 10.1016/j.actbio.2019.03.030. Epub 2019 Mar 14.
Ceramic fracture and debonding are the primary failures that follow ceramic inlay and can lead to stress and tooth fracture. In this study, we examined two designs-concave and flat-of the gingival cavity bottom for tooth cavities restored using ceramic inlays. We investigated the biomechanical behavior of ceramic inlay-restored teeth (concave and flat) through three-dimensional finite element analysis (FEA) and experimentally validated the results using an ultrahigh-speed camera. We conducted in vitro real-time recording of the deformation of a restored tooth during loading using an ultrahigh-speed camera. This technique enables further image registration to observe deformation variation and vector fields. The deformation vector fields revealed that the concave design moved the deformation toward the buccal side of the cavity bottom, whereas the flat design moved it toward the palatal side. These findings correlated with the FEA results, which indicated that the concave design constrained stress in the dentin cavity and relieved palatal stress. Our results suggest that incorporating a concave design in cavity preparation can improve the fracture resistance of ceramic inlay-restored teeth, preventing unrestorable fractures. The current study is the first to utilize an ultrahigh-speed camera in dental biomechanics, and such cameras are useful for nondestructive and dynamic analysis. STATEMENT OF SIGNIFICANCE: First utilize ultrahigh-speed cameras in dental biomechanics analysis. Tooth fracture videos captured by ultrahigh-speed camera helps us learn fracture mechanics in between tooth cavity design and ceramic inlay. Concave design leads to stress in safer areas that causes a less damaging fracture. Minimal invasive preparation by concave design strengthens tooth fracture resistance. Non-destructive data from ultrahigh-speed cameras combined with FEA can get more insight into how the stress and strain derived in biomaterials.
陶瓷的断裂和脱粘是紧随其后的主要失效模式，可能导致牙齿受力和断裂。在这项研究中，我们检查了两种用于陶瓷嵌体修复的牙洞的牙龈腔底部设计——凹面和平面。我们通过三维有限元分析（FEA）研究了陶瓷嵌体修复牙（凹面和平面）的生物力学行为，并使用超高速相机对结果进行了实验验证。我们使用超高速相机对加载过程中修复牙的变形进行了体外实时记录。这种技术可以进一步进行图像配准，以观察变形的变化和向量场。变形向量场表明，凹面设计将变形向腔底的颊侧移动，而平面设计则将其向腭侧移动。这些发现与 FEA 结果相关，表明凹面设计限制了牙本质腔中的应力，并减轻了腭侧的应力。我们的研究结果表明，在腔制备中采用凹面设计可以提高陶瓷嵌体修复牙的抗断裂能力，防止无法修复的断裂。本研究首次将超高速相机应用于口腔生物力学分析，此类相机对于非破坏性和动态分析非常有用。
首次在口腔生物力学分析中使用超高速相机。超高速相机捕获的牙齿断裂视频帮助我们了解牙洞设计和陶瓷嵌体之间的断裂力学。凹面设计导致在更安全的区域产生应力，从而导致破坏性较小的断裂。凹面设计的微创制备增强了牙齿的抗断裂能力。超高速相机的非破坏性数据与 FEA 相结合，可以更深入地了解生物材料中的应力和应变是如何产生的。
