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KMID : 1035320140410010019
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Korean Society for Dental Materials
2014 Volume.41 No. 1 p.19 ~ p.28
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Physical/mechanical properties and microstructure of dental lithium disilicate ceramics for chairside CAD/CAM restoration
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Kang Suk-Ho
Ahn Jin-Soo
Seo Deog-Gyu
Cho Byung-Hoon
Son Ho-Hyun
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Abstract
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Lithium disilicate ceramics can be used for one-visit restoration using chairside CAD/CAM. The aim of this study was to compare physical/mechanical properties of the two lithium disilicate ceramics for chairsideCAD/CAM restoration and to observe their microstructure. Before and after heat treatment, elastic modulus, biaxial flexural strength, surface hardness, fracture toughness, and coefficient of thermal expansion of IPS e.max CAD (Ivoclar Vivadent) and Rosetta SM (Hass) were tested. The crystalline structures were observed using field-emission scanning microscopy and x-ray diffraction analysis. IPS e.max CAD showed significantly higher elastic modulus than Rosetta SM. There were no significant differences in biaxial flexural strength between them either before or after heat treatment, but both ceramics showed significantly increased biaxial flexural strength after heat treatment. Surface hardness of IPS e.max CAD significantly decreased after heat treatment, but for Rosetta SM, it increased significantly. IPS e.max CAD showed higher surface hardness before heat treatment while Rosetta SM showed higher values after heat treatment. Both ceramics showed greatly increased fracture toughness after heat treatment. The FE-SEM images presented similar patterns of crystalline structure in the two ceramics but Rosetta SM had smaller crystallines after heat treatment. In the XRD analysis, they had similar patterns corresponding to the standard lithium metasilicate and lithium disilicate at each stage.
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KEYWORD
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biaxial flexural strength, CAD/CAM restoration, crystalline structure, lithium disilicate ceramics, surface hardness
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