IPS EMPRESS Glass-Ceramic

M. Guazzato et al.. Strength, Fracture Toughness and Microstructure of a Selection of All-Ceramic Materials. Part I. Pressable and Alumina Glass-Infiltrated Ceramics, Dent. Mater., 20,441-48 (2004). W. Holand et al., A Comparison of the Microstructuie and Properties of the IPS Empress 2 and the IPS Empress Glass-Ceramics, J. Biomed. Mater. Res., 53,297-303 (2000). 

The biomaterial must also demonstrate special abrasion properties that stand up to the oral environment. The most favorable properties are those demonstrated by natural teeth. If the surface of a glass-ceramic is too hard for example, it could dam e the antagonist tooth. However, if the biomaterial is too soft compared with natural dentition, it would wear too easily. Comprehensive tests simulating the actual oral conditions have been conducted in a mastication simulator. Heinzmann et al. (1990) and Krecji et al. (1993) were the first to show that the IPS EMPRESS glass-ceramic demonstrates favorable abrasion properties corresponding to those of natural teeth. Subsequent studies have confirmed these findings. It is very likely that this... 

The IPS EMPRESS glass-ceramic demonstrates an additional property favorable for the processing of the material in the dental laboratory. It begins to flow at temperatures between 1000°C and 1200°C, despite its crystal content of approximately 34 vol% leucite. Hence, the glass matrix reaches a viscosity of approximately 10 Pa s at these temperatures. Once relatively low pressure of 200-300 N is applied, the glass-ceramic demonstrates viscous flow. Given this property, dental restorations of virtually every shape can be formed from the material. 

The IPS EMPRESS glass-ceramic is produced with a base glass using controlled surface crystallization (Section 1.5). The material also contains additives that influence its processing temperature and stability and produce fluorescence. A raw glass-ceramic is produced in this controlled crystallization process. At a later stage, this raw material, in the form of ingots (Fig. 4-30) is used to fabricate dental restorations, (e.g., crowns, inlays) in the laboratory (Fig. 4-31). 

The procedure used by dental tedhnicians to fabricate the restorations includes the following steps. First, a wax model is produced on the basis of the impression of the clinical situation provided by the dentist. Figure 4-30 IPS EMPRESS glass-ceramic ingots. 

Figure 4-31 IPS EMPRESS glass-ceramic dental products (inlay, crowns, veneer).

The success of the IPS EMPRESS glass-ceramic as a dental restorative has been proven in comprehensive clinical tests and successful application worldwide since 1991. 

The IPS EMPRESS glass-ceramic is used worldwide to fabricate inlays, onlays, anterior and posterior crowns, and veneers. The material is not recommended for fabricating multi-unit dental bridges. Figure 4-34 shows four IPS EMPRESS inlays/onlays in a clinical situation. The clinical results of a six-year study show that the failure rate is approximately 2-3%. Most of the problems experienced thus far have been traced to preparation errors. An outline of the clinical results is presented by Brodbeck (1996). IPS EMPRESS is produced by Ivoclar Vivadent AG (Liechtenstein). 

El Ivoclar Vivadent / IPS Empress Heat-pressed, leucite-based glass-ceramic, used for inlays, onlays, veneers and crowns... 

E2 Ivoclar Vivadent / IPS Empress 2 Heat-pressed, glass-ceramic with lithium disilicate, used as core material in crowns and bridges... 

Some of the leucite crystals differ considerably in their outer shape from the type of natural leucite crystals. The base glass-ceramic thus produced is distributed by the manufacturer (Ivoclar Vivadent AG) in the form of glass-ceramic ingots in the IPS Empress dental restoration system for further processing in dental laboratories. To complete the formation of the final... 

As the crystal content of leucite of approximately 34 vol% in glass-ceramic of IPS Empress (Ermrich et al., 2001) is quite high, linear coefficients of... 

In comparison to the IPS Empress microstructure, a different type of leucite glass-ceramic was developed by Schweiger et al. (1999). The leucite-reinforced glass-ceramic was developed as a biomaterial for dental restoration. The material can easily be machined by a CAD/CAM system. The mechanical properties are characterized by a flexural strength of 135-160 MPa and a fracture toughness as of 1.3 MPa m (section ProCAD in Section 4.4.2 dental glass-ceramics). 

Figure 4-33 Schematic diagram of a glass-ceramic crown of IPS EMPRESS leucite glass-ceramic. Pressed glass-ceramic (dentin), sintered ceramic with opal glass-ceramic (incisal), and glaze.

IPS EMPRESS Cosmo (Zr02-Containing Glass-Ceramic)... 

Figure 4-39 Flexural strength of pressed glass-ceramic IPS EMPRESS 2 in comparison to other dental materials, natural tooth, and technical ceramics (Kappert 1998). a) ISO limit, b) tooth enamei, c) tooth dentin, d), e) ieucite-based ceramics, f) iPS EMPRESS , g) feldspar ceramic, h) mica glass-ceramic, i) sintered spinei and infiltrated glass, j) sintered AlgOg and infiltrated glass, k) IPS EMPRESS 2,1) dense sintered AI2O3.

Properties of Pressed Glass-Ceramic (Lithium Disilicate) of IPS EMPRESS 2 in Comparison to IPS EMPRESS (Layering Technique) (Leucite Glass-Ceramic) ... 

Figure 4-46 Micromechanical retention of the pressed glass-ceramic IPS EMPRESS 2 created after etching in 4.5% HF gel for 20 sec.

Schweiger M., Holand W., Frank M., Drescher H., and Rheinberger V., "IPS Empress 2 A New Pressable High Strength Glass-Ceramic for Esthetic All Ceramic Restoration," Quint. Dent. TechnoL, 22, 143-52 (1999). 

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