Department of Prosthodontics, Propaedeutic and Dental Materials, School of Dentistry, Kiel University, Germany.
Institute of Geochemistry and Petrology, ETH Zürich, Switzerland.
Dent Mater. 2019 May;35(5):713-729. doi: 10.1016/j.dental.2019.02.027. Epub 2019 Mar 7.
New lithium silicate/disilicate hot-pressed glass-ceramics are introduced into the dental market. It is known that the mechanical properties of this material depend on the microstructure, chemical composition, glass matrix, morphology of crystals, volume ratio crystal/glass, additive, and treatments. This contribution investigates how these factors affect the properties of the new generation of lithium silicate/disilicate hot-pressed glass-ceramics.
Three lithium silicate/disilicate hot-pressed glass-ceramics were investigated; IPS e.max Press (control group), Initial LiSi Press and Celtra Press. The specimens were prepared according to the manufacturers` instructions. Different methods; DTA, XRD, Raman, optical spectroscopy, SEM were used to characterize the properties of these materials before, after heat and etching treatments. The heat treatments (four firings) were performed according to the manufacturer's instructions (GC company) for veneering (initial LiSi) of LS2 glass-ceramics. The etching was performed according to the manufacturer's instruction. Vita ceramics etch gel (HF 5%) was used as an etching agent. The mechanical properties were investigated according to DIN EN ISO 6872:2015 and ASTM C 1327-08 instructions.
DTA and XRD analysis revealed that the transformation of the lithium silicate (LS) phase to the LS2 phase was completed for IPS e.max and Initial LiSi Press ingots while for Celtra Press ingots it was not. After pressing, the rod-shaped crystals were aligned parallel to the extrusion direction, while the platelet-shaped crystals having an interlocking microstructure were not. The mechanical properties depend on the microstructure, the chemical composition, the crystals morphology, the volume crystal/glass ratio, and the treatments (heat and etching). ZrO did not improved the mechanical properties. Etching with HF gel decreased the flexural strength. After four heat treatments, the biaxial flexural strength, the K, the roughness and the optical properties were affected. According to the HT-XRD, IPS e.max Press ingots can be hot pressed up to 900 °C, the initial LiSi Press ingots up to 940 °C and Celtra Press ingots up to 880 °C.
The properties of LS2 glass-ceramics depend on the chemical composition, the microstructure, the morphology of the crystals, the properties of the residual glass matrix, the volume ratio of crystal/glass, and the treatments (heat and etching).
新型硅酸锂/二硅酸锂热压玻璃陶瓷被引入牙科市场。已知该材料的机械性能取决于其微观结构、化学成分、玻璃基质、晶体形态、晶体/玻璃体积比、添加剂和处理方式。本研究旨在探讨这些因素如何影响新一代硅酸锂/二硅酸锂热压玻璃陶瓷的性能。
本研究共调查了三种硅酸锂/二硅酸锂热压玻璃陶瓷，即 IPS e.max Press（对照组）、初始 LiSi Press 和 Celtra Press。根据制造商的说明制备试件。采用 DTA、XRD、拉曼光谱、光学光谱、SEM 等不同方法对这些材料在加热和蚀刻处理前后的性能进行了表征。热（四次烧制）处理按照制造商（GC 公司）的指示进行，用于饰面（初始 LiSi）LS2 玻璃陶瓷。蚀刻按照制造商的说明进行，使用 Vita ceramics etch gel（HF 5%）作为蚀刻剂。根据 DIN EN ISO 6872:2015 和 ASTM C 1327-08 说明对机械性能进行了研究。
DTA 和 XRD 分析表明，LS 相向 LS2 相的转变对于 IPS e.max 和初始 LiSi Press 锭已完成，而 Celtra Press 锭则尚未完成。压制后，棒状晶体沿挤压方向平行排列，而具有联锁微观结构的板状晶体则没有。机械性能取决于微观结构、化学成分、晶体形态、晶体/玻璃体积比和处理（热和蚀刻）。ZrO 并没有改善机械性能。HF 凝胶蚀刻降低了弯曲强度。经过四次热处理，双轴弯曲强度、K 值、粗糙度和光学性能受到影响。根据 HT-XRD，IPS e.max Press 锭可以在 900°C 以下进行热压，初始 LiSi Press 锭可以在 940°C 以下进行热压，Celtra Press 锭可以在 880°C 以下进行热压。
LS2 玻璃陶瓷的性能取决于化学成分、微观结构、晶体形态、残余玻璃基质性能、晶体/玻璃体积比以及处理（热和蚀刻）。
