Centre of Adult Oral Health, Queen Mary University of London, Barts and The London School of Medicine and Dentistry, Institute of Dentistry, Turner Street, London, E12AD, UK.
Dent Mater. 2011 Nov;27(11):1153-61. doi: 10.1016/j.dental.2011.08.009. Epub 2011 Sep 17.
Leucite glass-ceramics with fine-grained leucite crystals promote improved mechanical strength and increased translucency. The objectives of the study were to optimize the microstructure of a fine-grained leucite glass-ceramic in order to increase its flexural strength and reliability as measured by its Weibull modulus.
Glass was prepared by a melt-derived method and ground into a powder (M1A). The glass crystallization kinetics were investigated using high temperature XRD and DSC. A series of two-step heat treatments with different nucleation/crystal growth temperatures and holds were carried out to establish the optimized crystallization heat treatment. Glass-ceramics were characterized using XRD, SEM and dilatometry. The glass-ceramic heat treated at the optimized crystallization parameters (M1A(opt)) was both sintered (SM1A(opt)) and heat extruded (EM1A(opt)) into discs and tested using the biaxial flexural strength (BFS) test.
High temperature XRD suggested leucite and sanidine crystallization at different temperatures. Optimized crystallization resulted in an even distribution of fine leucite crystals (0.15 (0.09) μm(2)) in the glassy matrix, with no signs of microcracking. Glass-ceramic M1A(opt) showed BFS values of [mean (SD), MPa]: SM1A(opt)=252.4 (38.7); and EM1A(opt)=245.0 (24.3). Weibull results were: SM1A(opt); m=8.7 (C.I.=7.5-10.1) and EM1A(opt); m=11.9 (C.I.=9.3-15.1). Both experimental groups had a significantly higher BFS and characteristic strength than the IPS Empress Esthetic glass-ceramic, with a higher m value for the EM1A(opt) material (p<0.05).
A processable fine-grained leucite glass-ceramic with high flexural strength and improved reliability was the outcome of this study.
具有细晶粒白榴石的锂辉石玻璃陶瓷可提高机械强度和透光率。本研究的目的是优化细晶粒白榴石玻璃陶瓷的微观结构，以提高其弯曲强度和可靠性，其可靠性通过韦布尔模数来衡量。
采用熔融法制备玻璃并研磨成粉末（M1A）。使用高温 XRD 和 DSC 研究玻璃的结晶动力学。进行了一系列具有不同成核/晶体生长温度和保温时间的两步热处理，以确定最佳的结晶热处理。使用 XRD、SEM 和热膨胀计对玻璃陶瓷进行了表征。在优化的结晶参数下处理的玻璃陶瓷（M1A(opt)）被烧结（SM1A(opt)）和热挤压（EM1A(opt)）成圆盘，并使用双轴弯曲强度（BFS）测试进行测试。
高温 XRD 表明白榴石和钠长石在不同温度下结晶。优化结晶导致细小白榴石晶体（0.15（0.09）μm²）在玻璃基质中均匀分布，没有微裂纹的迹象。玻璃陶瓷 M1A(opt) 的 BFS 值为[平均值（标准差），MPa]：SM1A(opt)=252.4（38.7）；EM1A(opt)=245.0（24.3）。韦布尔结果为：SM1A(opt)；m=8.7（置信区间为 7.5-10.1）和 EM1A(opt)；m=11.9（置信区间为 9.3-15.1）。两个实验组的 BFS 和特征强度均明显高于 IPS Empress Esthetic 玻璃陶瓷，而 EM1A(opt)材料的 m 值更高（p<0.05）。
本研究得到了一种可加工的具有高弯曲强度和可靠性的细晶粒白榴石玻璃陶瓷。
