Self-Healing, Fracture Resistant Restorative Ceramics

自愈、抗断裂修复陶瓷

• 批准号: 6435311
• 负责人: JASON A GRIGGS
• 金额: $ 22.87万
• 依托单位: TEXAS A&M UNIVERSITY HEALTH SCIENCE CTR
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-01-01 至 2004-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6435311
• 关键词: biomaterial compatibility; biomaterial evaluation; cell mediated lymphocytolysis test; ceramics; clay; composite resins; dental material wear; glass; hardness; oral facial restoration material; porcelain; tensile strength; tooth surface; transmission electron microscopy; water

Dental ceramics are increasingly prolific as restorative materials because of their esthetic appearance and their intrinsic wear resistance, thermal insulation, and biocompatibility. Unfortunately, the currently available dental ceramics are brittle in comparison to dental alloys. This lack of fracture resistance compromises their strength and reliability, resulting in decreased lifetime expectancy. Previous strategies for increasing the lifetimes of dental ceramics have focused on improving the initial strength and tolerance to future damage; however, without a mechanism for repair, damage accumulates, and failure is inevitable. In contrast, natural materials have relatively low resistance to mechanical damage, but their usefulness is maintained over time by healing any damage that is sustained before it accumulates. The overall objective of this project is study self-healing mechanisms by which dental ceramics may exhibit mechanical fatigue resistance and increased longevity. This objective will be accomplished through incorporation of smectite clay particles in hydrothermal glass to form ceramic matrix composites, which will close cracks through the swelling of reinforcing particles. The experimental materials will be designed for use in esthetic, all-ceramic dental restorations. A commercially available low fusing ceramic (Duceram LFC) will be used as the control material for investigation of the following hypotheses: l) moisture- activated swelling of clay particles is a source of increased fracture resistance, 2) a maximum mean free path of 45 mum between reinforcing particles acts as a threshold for increased fracture resistance, 3) a mean reinforcing particle size smaller than 0.39 mum will result in materials with greater translucency than currently available ceramic core materials, 4) smectite clay-reinforced porcelains will exhibit similar or superior biocompatibility compared to unreinforced dental porcelain, and 5) smectite clay-reinforced porcelains will exhibit hardness and abrasive potential lower than those of unmodified dental I porcelain. These efforts may elucidate the mechanisms of fatigue failure and may result in materials that will fill the public demand for long-lasting, esthetic dental restorations.

牙科陶瓷由于其美观的外观和内在的耐磨性、隔热性和生物相容性而越来越多地用作修复材料。 不幸的是，目前可用的牙科陶瓷与牙科合金相比是易碎的。 这种抗断裂性的缺乏损害了它们的强度和可靠性，导致预期寿命降低。以前增加牙科陶瓷寿命的策略主要集中在提高初始强度和对未来损伤的耐受性;然而，如果没有修复机制，损伤就会累积，失败是不可避免的。 相比之下，天然材料对机械损伤的抵抗力相对较低，但随着时间的推移，它们的有用性通过在累积之前治愈任何持续的损伤而得以保持。本项目的总体目标是研究自愈合机制，通过该机制牙科陶瓷可以表现出机械疲劳抗力和延长寿命。 这一目标将通过在水热玻璃中掺入蒙皂石粘土颗粒以形成陶瓷基复合材料来实现，所述陶瓷基复合材料将通过增强颗粒的溶胀来闭合裂纹。实验材料将被设计用于美观的全瓷牙科修复体。 一种市售的低熔点陶瓷，（Duceram LFC）将用作研究以下假设的对照材料：1）粘土颗粒的水分活化膨胀是增加的抗断裂性的来源，2）增强颗粒之间45 μ m的最大平均自由程作为增加的抗断裂性的阈值，3）小于0.39 μ m的平均增强颗粒尺寸将导致材料具有比目前可获得的陶瓷芯材料更大的相容性，4）蒙脱石粘土增强的瓷与未增强的牙科瓷相比将表现出相似或上级的生物相容性，和5）蒙皂石粘土增强的瓷将表现出比未改性的牙科I瓷更低的硬度和磨损潜力。 这些努力可能阐明疲劳失效的机制，并可能导致材料，将满足公众对持久的，美观的牙科修复的需求。