HIGH TOUGHNESS TEXTURED DENTAL GLASS CERAMICS

高韧性纹理牙科玻璃陶瓷

• 批准号: 6350617
• 负责人: Isabelle L Denry
• 金额: $ 16.28万
• 依托单位: OHIO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-02-01 至 2003-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6350617
• 关键词: X ray crystallography; biomaterial development /preparation; ceramics; dental materials; glass; magnesium; mechanical stress; metal dental material; nuclear magnetic resonance spectroscopy; oxides; scanning electron microscopy; transmission electron microscopy

Dental ceramics are chemically durable, biocompatible and have the greatest potential for achieving superior esthetics. They are currently gaining new interest while metal-based restorative products are progressively being eliminated from the oral environment. During the past five years, a novel technique has been introduced in dentistry for fabricating all-ceramic dental restorations: hot-pressing. However, most of the currently available pressable ceramics have low fracture toughness, implying possible failure of all-ceramic restorations. The overall objective of the proposed research is to develop high-toughness textured glass-ceramics for hot-pressed all- ceramic restorations. The texture will be obtained during hot-pressing of the nucleated glass. This unique microstructure will be associated with an anisotropic increase in fracture toughness, due to the alignment of the plate-shaped crystals in the direction of pressing. The strategy is to investigate the effect of magnesium oxide on the thermal and mechanical properties of a glass-ceramic in the system Li2O-Na2O-K2O-CaO-MgO-SiO2-F. The hypothesis to be tested is that increasing concentrations of magnesium will increase the fluidity of the glass and its working range. The nucleation and crystallization behavior of the glasses will be studied by x-ray diffraction, scanning and transmission electron microscopy and nuclear magnetic resonance spectroscopy. The thermal properties will be analyzed by differential thermal analysis and dilatometry. The biaxial flexural strength and fracture toughness will also be investigated. The study of thermal and mechanical properties will allow material selection for hot-pressing. Hot-pressing studies will be divided in two steps, first a simplified, low fusing version of the glass-ceramic material studied will be hot-pressed as control. Second, the glass ceramic material itself will be hot-pressed. The optical scattering and absorption coefficients will be calculated from reflectance measurements. The mechanical properties of both materials will be tested in both the direction of pressing and the normal direction, the degree of texture will be characterized by SEM. The effect of annealing on the crack healing behavior and flexural strength of the glass-ceramic developed will be investigated last.

牙科陶瓷具有化学耐久性、生物相容性，并且具有实现卓越美学的最大潜力。 它们目前引起了新的兴趣，而金属基修复产品正逐渐从口腔环境中消失。 在过去的五年中，牙科领域引入了一种用于制造全瓷牙齿修复体的新技术：热压。 然而，目前大多数可压制陶瓷的断裂韧性较低，这意味着全瓷修复体可能会失败。 本研究的总体目标是开发用于热压全瓷修复体的高韧性织构微晶玻璃。 纹理将在核玻璃热压过程中获得。 由于板状晶体在压制方向上的排列，这种独特的微观结构将与断裂韧性的各向异性增加相关。 该策略是研究氧化镁对 Li2O-Na2O-K2O-CaO-MgO-SiO2-F 体系中微晶玻璃热性能和机械性能的影响。 要测试的假设是增加镁的浓度将增加玻璃的流动性及其工作范围。 将通过X射线衍射、扫描和透射电子显微镜以及核磁共振波谱研究玻璃的成核和结晶行为。 将通过差热分析和膨胀测定法来分析热性能。 还将研究双轴弯曲强度和断裂韧性。 热性能和机械性能的研究将有助于选择热压材料。 热压研究将分为两个步骤，首先将热压所研究的玻璃陶瓷材料的简化、低熔点版本作为对照。 其次，玻璃陶瓷材料本身将被热压。 光学散射和吸收系数将根据反射率测量来计算。 将在压制方向和法线方向上测试两种材料的力学性能，并通过SEM表征织构程度。 最后将研究退火对所开发的微晶玻璃的裂纹愈合行为和弯曲强度的影响。