Dentin glass-ceramic materials

The properties of both materials systems have been presented in detail by Schweiger et al. (1996, 1998) and Kakehashi et al. (1998). The Zr02 posts are cylindrical rods with a conical point tip. The conical angle is 6°. The posts were produced in two sizes with a diameter of either 1.4 or 1.7 mm. The post surface was roi ened to optimize the strength of the bond between the Zr02 and the glass-ceramic dentin core buildup and between the Zr02 and the root. The surface roi ness measures 0.5—1.2 pm. 

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.

The most important properties of the dentin and incisal materials are shown in Table 4-19. The coefficient of linear thermal expansion plays an important role in the optimal joining of ious types of apatite-leucite glass-ceramics and the Zr02-rich opaquer, which are applied to the different metals. Therefore, CTE of the opaquer has been included as a comparative value in Table 4-19. A comparison of CTE of glass-ceramics and of the opaquer with that of metals clearly shows that the application of the glass-ceramic to the metal framework systematically builds up compressive strain. As a result, the finished dental product demonstrates surface tension and a controlled increase in strength, ensuring retention on the substructure. 

Some dental technicians choose to apply an additional veneer to the shoulder region of dental crowns and bridges. As a result, metal is no longer visible in the gingival region. Thus the metal is optimally masked. This tedmique requires that the shoulder material from the additional assortment of glass-ceramics be applied prior to the sintering of dentin and incisal materials. 

In terms of quantity, the incisal and dentin materials comprise the largest part of the apatite-leucite glass-ceramics of the IPS d.SIGN system. Their microstructure and properties are described in Section 2.4.6. The main applications of these glass-ceramics include dental crowns and multi-unit bridges. 

Apart from the dentin and incisal materials, the IPS d.SIGN system includes further glass-ceramics of the apatite-leucite type as well as special glasses. The additional assortment of materials comprises base-kit, deep-dentin-kit, margin kit, impulse kit (with Effect and Transpa), gingiva kit, essence kit, stains kit (with glaze), and add-on materials. These system... 

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