Glass-ceramics have found widespread use in dentistry due to their favorable properties: biocompatibility, chemical inertness, high fracture strength and toughness, superior esthetics, color stability, and translucence. The objective of this work was to develop a tough, strong and machinable glass-ceramic based on the lithium (LS) crystal phase. We designed a glass composition aimed to yield LS crystals after proper treatment. We melted, casted, and crystallized the glass for a favorable microstructure. We then characterized its microstructure and relevant mechanical, optical and chemical properties with several experimental tools. We also measured the residual stresses. This newly developed glass-ceramic shows a house-of-cards microstructure composed of 50% vol. plate-like LS crystals of 5–25 μm, randomly dispersed in a glassy matrix. Lithium disilicate (12% vol.), two minor crystal phases, and 34% vol. residual glass are also present. The average fracture toughness measured by the double torsion technique is 3.5 ± 0.5 MPa m. The average fracture strength, evaluated by the ball-on-three balls (B3B) technique, is 450 ± 40 MPa. The elastic modulus, determined by nanoindentation, is 124 ± 2 GPa, the linear thermal expansion coefficient is 13.6 × 10 °C, and the solubility in 4%vol. acetic acid is 215 ± 30 μg/cm, which is below the limit established by the ISO 6872 standard for some applications, but improper for uncoated use. These properties could still be optimized. The improved toughness, strength, and reasonable machinability indicate that, after optimization, this glass-ceramic could be a very promising candidate for dental restorative applications.

中文翻译：

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新型、坚韧、坚固的偏硅酸锂牙科玻璃陶瓷


微晶玻璃因其良好的特性而在牙科领域得到广泛应用：生物相容性、化学惰性、高断裂强度和韧性、卓越的美观性、颜色稳定性和半透明性。这项工作的目标是开发一种坚韧、坚固且可加工的基于锂 (LS) 晶相的玻璃陶瓷。我们设计了一种玻璃成分，旨在经过适当处理后产生 LS 晶体。我们对玻璃进行熔化、铸造和结晶，以获得良好的微观结构。然后，我们使用几种实验工具表征了其微观结构以及相关的机械、光学和化学性能。我们还测量了残余应力。这种新开发的微晶玻璃显示出由 50% 体积的玻璃组成的纸牌屋微观结构。 5-25 μm 的板状 LS 晶体，随机分散在玻璃状基质中。二硅酸锂（12% 体积），两个次要晶相，34% 体积。还存在残留玻璃。通过双扭转技术测得的平均断裂韧性为3.5±0.5MPa·m。通过三球球 (B3B) 技术评估的平均断裂强度为 450 ± 40 MPa。通过纳米压痕测定其弹性模量为124±2GPa，线性热膨胀系数为13.6×10℃，溶解度为4%vol。乙酸为 215 ± 30 µg/cm，低于 ISO 6872 标准为某些应用制定的限值，但不适合无涂层使用。这些属性仍然可以优化。改进的韧性、强度和合理的机械加工性表明，经过优化后，这种微晶玻璃可能成为牙科修复应用中非常有前途的候选材料。