TY - JOUR
T1 - Microstructural development during heat treatment of a commercially available dental-grade lithium disilicate glass-ceramic
AU - Ortiz, Angel L.
AU - Borrero-López, Oscar
AU - Guiberteau, Fernando
AU - Zhang, Yu
N1 - Publisher Copyright:
© 2019 The Academy of Dental Materials
PY - 2019/5
Y1 - 2019/5
N2 - Objective: To elucidate the microstructural evolution of a commercial dental-grade lithium disilicate glass-ceramic using a wide battery of in-situ and ex-situ characterization techniques. Methods: In-situ X-ray thermo-diffractometry experiments were conducted on a commercially available dental-grade lithium disilicate glass-ceramic under both non-isothermal and isothermal heat treatments in air. These analyses were complemented by experiments of ex-situ X-ray diffractometry, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, differential scanning calorimetry, and field-emission scanning electron thermo-microscopy. Results: It was found that the non-fired blue block consists of ∼40 vol % crystals embedded in a glass matrix. The crystals are mainly lithium metasilicate (Li 2 SiO 3 ) along with small amounts of lithium orthophosphate (Li 3 PO 4 ) and lithium disilicate (Li 2 Si 2 O 5 ). Upon heating, the glassy matrix in the as-received block first crystallizes partially as SiO 2 (i.e., cristobalite) at ∼660 °C. Then, the SiO 2 crystals react with the original Li 2 SiO 3 crystals at ∼735 °C, forming the desired Li 2 Si 2 O 5 crystals by a solid-state reaction in equimolar concentration (SiO 2 + Li 2 SiO 3 → Li 2 Si 2 O 5 ). Precipitation of added colourant Ce ions in the form of CeO 2 appears at ∼775 °C. These events result in a glass-ceramic material with the aesthetic quality and mechanical integrity required for dental restorations. It also has a microstructure consisting essentially of elongated Li 2 Si 2 O 5 grains in a glassy matrix plus small cubic CeO 2 grains at the outermost part of the surface. Significance: It was found that by judiciously controlling the heat treatment parameters, it is possible to tailor the microstructure of the resulting glass-ceramics and thus optimizing their performance and lifespan as dental restorations.
AB - Objective: To elucidate the microstructural evolution of a commercial dental-grade lithium disilicate glass-ceramic using a wide battery of in-situ and ex-situ characterization techniques. Methods: In-situ X-ray thermo-diffractometry experiments were conducted on a commercially available dental-grade lithium disilicate glass-ceramic under both non-isothermal and isothermal heat treatments in air. These analyses were complemented by experiments of ex-situ X-ray diffractometry, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, differential scanning calorimetry, and field-emission scanning electron thermo-microscopy. Results: It was found that the non-fired blue block consists of ∼40 vol % crystals embedded in a glass matrix. The crystals are mainly lithium metasilicate (Li 2 SiO 3 ) along with small amounts of lithium orthophosphate (Li 3 PO 4 ) and lithium disilicate (Li 2 Si 2 O 5 ). Upon heating, the glassy matrix in the as-received block first crystallizes partially as SiO 2 (i.e., cristobalite) at ∼660 °C. Then, the SiO 2 crystals react with the original Li 2 SiO 3 crystals at ∼735 °C, forming the desired Li 2 Si 2 O 5 crystals by a solid-state reaction in equimolar concentration (SiO 2 + Li 2 SiO 3 → Li 2 Si 2 O 5 ). Precipitation of added colourant Ce ions in the form of CeO 2 appears at ∼775 °C. These events result in a glass-ceramic material with the aesthetic quality and mechanical integrity required for dental restorations. It also has a microstructure consisting essentially of elongated Li 2 Si 2 O 5 grains in a glassy matrix plus small cubic CeO 2 grains at the outermost part of the surface. Significance: It was found that by judiciously controlling the heat treatment parameters, it is possible to tailor the microstructure of the resulting glass-ceramics and thus optimizing their performance and lifespan as dental restorations.
KW - Dental materials
KW - Glass-ceramics
KW - In-situ characterizations
KW - Lithium disilicate
KW - Microstructural evolution
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U2 - 10.1016/j.dental.2019.02.011
DO - 10.1016/j.dental.2019.02.011
M3 - Article
C2 - 30827800
AN - SCOPUS:85062155486
SN - 0109-5641
VL - 35
SP - 697
EP - 708
JO - Dental Materials
JF - Dental Materials
IS - 5
ER -