Microstructural development during heat treatment of a commercially available dental-grade lithium disilicate glass-ceramic

Angel L. Ortiz, Oscar Borrero-López, Fernando Guiberteau, Yu Zhang

Research output: Contribution to journalArticle

Abstract

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.

Original languageEnglish (US)
Pages (from-to)697-708
Number of pages12
JournalDental Materials
Volume35
Issue number5
DOIs
StatePublished - May 1 2019

Fingerprint

Glass ceramics
Tooth
Lithium
Hot Temperature
Heat treatment
Crystals
Electron Scanning Microscopy
Field emission
X-Rays
Restoration
X-Ray Emission Spectrometry
Differential Scanning Calorimetry
Therapeutics
Esthetics
Microstructure
Silicon Dioxide
Heating
Glass
Microstructural evolution
Ceramic materials

Keywords

  • Dental materials
  • Glass-ceramics
  • In-situ characterizations
  • Lithium disilicate
  • Microstructural evolution

ASJC Scopus subject areas

  • Materials Science(all)
  • Dentistry(all)
  • Mechanics of Materials

Cite this

Microstructural development during heat treatment of a commercially available dental-grade lithium disilicate glass-ceramic. / Ortiz, Angel L.; Borrero-López, Oscar; Guiberteau, Fernando; Zhang, Yu.

In: Dental Materials, Vol. 35, No. 5, 01.05.2019, p. 697-708.

Research output: Contribution to journalArticle

Ortiz, Angel L. ; Borrero-López, Oscar ; Guiberteau, Fernando ; Zhang, Yu. / Microstructural development during heat treatment of a commercially available dental-grade lithium disilicate glass-ceramic. In: Dental Materials. 2019 ; Vol. 35, No. 5. pp. 697-708.
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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.

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