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 journalArticlepeer-review


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
Issue number5
StatePublished - May 2019


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

ASJC Scopus subject areas

  • General Materials Science
  • General Dentistry
  • Mechanics of Materials


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