Departamento de Ingeniería Mecánica, Energética y de los Materiales, Universidad de Extremadura, 06006 Badajoz, Spain.
Department of Biomaterials and Biomimetics, New York University College of Dentistry, NY 10010, USA; Programa de Pós-Graduação em Ciências Odontológicas, Universidade Federal de Santa Maria, Santa Maria, Brazil.
Dent Mater. 2020 May;36(5):645-659. doi: 10.1016/j.dental.2020.03.011. Epub 2020 Apr 8.
To elucidate the compositional and microstructural developments of a novel lithium silicate glass-ceramic during its crystallization cycle.
Blocks of a lithium silicate glass-ceramic (Obsidian®, Glidewell Laboratories) were cut into 1mm thick plates and polished to 1μm finish. Some of them were crystallized prior to polishing. Firstly, ex situ compositional and microstructural characterizations of both the pre- and post-crystallized samples were performed by wavelength dispersive X-ray fluorescence, field-emission scanning electron microscopy, and X-ray diffractometry. Secondly, the pre-crystallized samples were subjected to in situ compositional and microstructural characterizations under non-isothermal heating by simultaneous thermogravimetry/differential scanning calorimetry, X-ray thermo-diffractometry, and field-emission scanning electron thermo-microscopy.
The microstructure of pre-crystallized Obsidian® consists of an abundant population of perlitic-like/dendritic lithium silicate (LiSiO) nanocrystals in a glass matrix. Upon heating, the residual glassy matrix does not crystallize into any form of SiO; elemental oxides do not precipitate unless over-heated above 820°C; and the LiSiO nanocrystals do not react with the glassy matrix to form typical lithium disilicate (LiSiO) crystals. Nonetheless, the LiSiO nanocrystals grow and spheroidize through the solution-reprecipitation process in the softened glass, and new lithium orthophosphate (LiPO) nanocrystals precipitate from the glass matrix.
The identification of compositional and microstructural developments of Obsidian® indicates that, by controlling the firing conditions, it is possible to tailor its microstructure, which in turn could affect its mechanical and optical properties, and ultimately its clinical performance.
阐明一种新型硅酸锂玻璃陶瓷在其结晶循环过程中的组成和微观结构发展。
将硅酸锂玻璃陶瓷（Obsidian®，Glidewell Laboratories）块切割成 1mm 厚的板，并用 1μm 的抛光剂进行抛光。其中一些在抛光前进行了结晶。首先，通过波长色散 X 射线荧光、场发射扫描电子显微镜和 X 射线衍射对预结晶和后结晶样品的组成和微观结构进行了原位分析。其次，通过同步热重/差示扫描量热法、X 射线热衍射法和场发射扫描电子热显微镜对预结晶样品在非等温加热下进行了原位组成和微观结构分析。
预结晶的 Obsidian®的微观结构由大量类似珍珠母/树枝状的硅酸锂（LiSiO）纳米晶组成，分布在玻璃基质中。加热时，残余的玻璃基质不会结晶成任何形式的 SiO；除非过热到 820°C 以上，否则元素氧化物不会沉淀；并且 LiSiO 纳米晶不会与玻璃基质反应形成典型的二硅酸锂（LiSiO）晶体。尽管如此，LiSiO 纳米晶通过在软化玻璃中的溶解-再沉淀过程生长并球化，并且新的磷酸锂（LiPO）纳米晶从玻璃基质中沉淀出来。
Obsidian®的组成和微观结构发展的鉴定表明，通过控制烧制条件，可以调整其微观结构，从而影响其机械和光学性能，并最终影响其临床性能。
