Chemical strengthening of leucite-containing dental ceramics

Fischer, J; Pospiech, Peter; Gernet, Wolfgang

doi:10.1016/0955-2219(92)90035-c

Cited by 3 publications

(2 citation statements)

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“…In a microstructural modification driven by ion exchange, external surfaces exposed to NaI or NaCl salt baths were enriched in sodium, shifting the chemical composition toward soda feldspar and away from the leucite phase field (120). Such treatment led to a decreased leucite concentration and a stabilization of cubic leucite in the treated layer, both of which reduced the thermal expansion coefficient relative to untreated internal ceramic.…”

Section: Microstructural Modificationsmentioning

confidence: 99%

Ceramics in Restorative and Prosthetic Dentistry

Kelly

1997

Annu. Rev. Mater. Sci.

277

175

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This review is intended to provide the ceramic engineer with information about the history and current use of ceramics in dentistry, contemporary research topics, and potential research agenda. Background material includes intra-oral design considerations, descriptions of ceramic dental components, and the origin, composition, and microstructure of current dental ceramics. Attention is paid to efforts involving net-shape processing, machining as a forming method, and the analysis of clinical failure. A rationale is presented for the further development of all-ceramic restorative systems. Current research topics receiving attention include microstructure/processing/property relationships, clinical failure mechanisms and in vitro testing, wear damage and wear testing, surface treatments, and microstructural modifications. The status of the field is critically reviewed with an eye toward future work. Significant improvements seem possible in the clinical use of ceramics based on engineering solutions derived from the study of clinically failed restorations, on the incorporation of higher levels of "biomimicry" in new systems, and on the synergistic developments in dental cements and adhesive dentin bonding. OVERVIEW Ceramics were first used successfully in dentistry in 1774, at a time when toothcolored replacements were made of ivory, bone, wood, animal teeth, or expensive extracted teeth obtained from human "donors." None of these biologically 1 The US Government has the right to retain a nonexclusive, royalty-free license in and to any copyright covering this paper.

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Section: Microstructural Modificationsmentioning

confidence: 99%

Ceramics in Restorative and Prosthetic Dentistry

Kelly

1997

Annu. Rev. Mater. Sci.

277

175

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“…It is dimorphic: above 600°C leucite has a cubic unit cell with parameter a = 1.343 nm whereas below this temperature it has a tetragonal unit cell with parameters a = 1.306 nm and c = 1.375 nm. This transition involves a volume expansion (of approximately 3.2%) producing the development of thermally induced stresses upon cooling, which is required for thermal compatibility of dental porcelain with the alloys (Mackert et al, 1986;Fischer et al, 1992;Piché et al, 1994). The cubic phase shows the smallest thermal expansion coefficient of both-that is, 12 to 18 × 10 −6 /°C for the cubic phase and from 22 to 25 × 10 −6 /°C for the tetragonal phase.…”

Section: Discussionmentioning

confidence: 99%

Structural and Chemical Analysis of Micro-sized Particles Found in Aluminous Electrical Porcelains

1999

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Uncommon, micro-sized particles with different morphologies were found in sintered aluminous electrical porcelains. The presence of these particles seems to be relatively insensitive to changes in composition of the porcelain system as well as in firing temperatures. X-ray energy-dispersive spectrometry (EDS) microanalysis showed that some particles, those with very well–defined geometries, were composed of K, Si, Al, and O with empirical formula KAlSi2O6—that is, leucite particles. Other particles showed less well–defined geometries, including some composed of Na, Si, Al, and O, corresponding to a sodium aluminum silicate structure, and others of K, Si, Na, Al, and O, corresponding to the leucite composition, where some K has been substituted for Na. The well–defined geometry particles were detected most often, and diffraction analysis with backscattering electrons showed that their unit cell was cubic, with unit cell parameter a = 1.343 nm. The formation of these particles may be the result of the relatively high concentration of K2O and/or Na2O in some very localized zones of the glassy phase due to weak coupling (e.g., alkali-enriched or -depleted melts) during diffusion at a slow cooling rate in the presence of catalytic agents such as TiO2.

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