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.

牙科陶瓷在化学上耐用，具有生物相容性，并且具有实现优质美学的最大潜力。 他们目前正在获得新的兴趣，而从口腔环境中逐渐消除了基于金属的修复产品。 在过去的五年中，牙科中引入了一种新颖的技术，用于制造全陶瓷牙科修复体：热压。 但是，大多数当前可用的可挤压陶瓷具有低断裂韧性，这意味着全陶瓷修复体可能失败。 拟议的研究的总体目的是开发用于热压全陶瓷修复体的高阻形质感玻璃陶瓷。 纹理将在成核玻璃热压期间获得。 这种独特的微观结构将与骨折韧性的各向异性增加有关，这是由于板状晶体沿压力的方向对齐。 该策略是研究氧化镁对系统LI2O-NA2O-K2O-CAO-MGO-SIO2-F的玻璃陶瓷的热和机械性能的影响。 要测试的假设是，镁浓度的增加将增加玻璃的流动性及其工作范围。 玻璃的成核和结晶行为将通过X射线衍射，扫描和透射电子显微镜以及核磁共振光谱研究。 将通过差分分析和扩张法对热性能进行分析。 还将研究双轴弯曲强度和断裂韧性。 对热和机械性能的研究将允许材料选择进行热压。 热压研究将分为两个步骤，首先是研究的玻璃陶瓷材料的简化，低融合的版本将被热贴作为控制。 其次，玻璃陶瓷材料本身将是热压的。 光散射和吸收系数将根据反射率测量计算。 两种材料的机械性能都将在按压方向和正常方向上测试，纹理的程度将以SEM为特征。 退火对开发的玻璃陶瓷的裂纹愈合行为和弯曲强度的影响将进行。