Alumina-glass dental composites

S.-J. Lee, W. M. Kriven and H.-M. Kim, Shrinkage-Free, Alumina-Glass Dental Composites via Aluminium... 

FIGURE 12.5 Surface traces of indentation cracks in alumina-glass dental composite by backscattered scanning electron microscopy (SEM). Grain bridging sites are near the arrows in (a) and transgranular fracture sites in (ft). (From Ref. 21.)... 

W. D. Wolf, K. J. Vaidya, and L. Falter Francis, Mechanical properties and failure analysis of alumina-glass dental composites, Journal of the American Ceramic Society 79 1769-1776(1996). 

Wilson et al. [25] analyzed various brands of commercial cements and specified their possible composition, properties, and microstructure. Wilson et al. report the most representative and comprehensive data on commercial porcelain dental cements. These cements consist of powdered alumina-lime-silica glass mixed with phosphoric acid that formed a hard and translucent product. The starter glass powder consists of 31.5-41.6 wt% silica, 27.2-29.1 wt% alumina, 7.7-9.0wt% calcium oxide, 7.7-11.2 wt% sodium oxide, 13.3-22 wt% fluorine and small amounts of phosphorous and zinc oxides. Often very small amounts of magnesium and strontium oxides are also present. 

Gonzaga CC, Yoshimura HN, Cesar PF, Miranda Jr WG. Subcritical crack growth in porcelains, glass-ceramics and glass-infiltrated alumina composite for dental restorations. Journal of Materials Science Materials in Medicine 2009 20(5) 1017-1024. 

Satisfactory clinical performance of In-Ceram dental restorations has been reported [23], and further improvement of the chemical durability and wear behaviour of these glass/alumina composites has been achieved by using diamond-like carbon coatings [17]. 

EFFECTS OF MICROSTRUCTURAL ANISOTROPY ON FRACTURE BEHAVIOR OF HEAT-PRESSED GLASS-CERAMICS AND GLASS-INFILTRATED ALUMINA COMPOSITES FOR DENTAL RESTORATIONS... 

The mechanical properties and microstructure of El, E2 and 1C processed according to the manufacturer s recommendations are well documented in the literature. However, there are few studies evaluating the effects of microstructural anisotropy on the mechanical properties of dental ceramics. The aim of this work was to investigate the effects of microstructural anisotropy associated with the sample geometry on fracture behavior of three dental ceramics (two glass-ceramic prepared by heatpressing method and a glass-infiltrated alumina composite). 

The dental ceramics used in this study are described in Table I. Materials were selected in order to provide varied microstructures a) the glass-ceramic El is expected to have a homogeneous microstructure and isotropic properties b) the glass-ceramic E2 is expected to have anisotropic properties due to alignment of lithium disilicate fibers and c) the glass-infiltrated alumina composite IC, may have particle orientation, which could affect the mechanical properties. 

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