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.

牙科陶瓷因其美观的外观以及固有的耐磨性、隔热性和生物相容性而作为修复材料越来越多。 不幸的是，与牙科合金相比，目前可用的牙科陶瓷很脆。 抗断裂性的缺乏会损害其强度和可靠性，导致预期寿命缩短。以前延长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，损坏就会不断累积，故障就不可避免。 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，它们的有用性可以通过治愈累积之前所遭受的任何损伤来保持。该项目的总体目标是研究牙科陶瓷的自愈机制，通过该机制，牙科陶瓷可以表现出抗机械疲劳性并延长使用寿命。 这一目标将通过在水热玻璃中掺入蒙皂石粘土颗粒形成陶瓷基复合材料来实现，该复合材料将通过增强颗粒的膨胀来闭合裂缝。实验材料将设计用于美观的全瓷牙齿修复体。 市售低熔点陶瓷 (Duceram LFC) 将用作控制材料，用于研究以下假设：l) 粘土颗粒的水分激活膨胀是增加断裂抗力的一个来源，2) 最大平均自由程为 45增强颗粒之间的 mum 是提高抗断裂性的阈值，3) 平均增强颗粒尺寸小于 0.39 mum 将导致材料比目前可用的陶瓷芯材料具有更大的半透明度，4) 蒙皂石与未增强的牙科瓷相比，粘土增强瓷将表现出相似或更好的生物相容性，并且5)蒙脱石粘土增强瓷将表现出比未改性牙科瓷低的硬度和磨蚀潜力。 这些努力可能会阐明疲劳失效的机制，并可能产生满足公众对持久、美观的牙齿修复体需求的材料。