Dicor glasses

Dicor glass-ceramic, 12 635-636 Dicots, fibers from, 21 18 Dicotyledonous grains, 26 267 Dictamine, 2 107... 

The kinetics of mica crystallization in DICOR glass-ceramic was studied by Bapta et al. (1996). The formal kinetic parameters were established according to the JMAK equation (Eq. 1-6 in Section 1.4.3). The activation energy of crystallization was determined as 203 kj moT the formal reaction order n as 3.4 0.2 and the pre-exponential factor as 2.88 x 10 s ... 

This development, which dates back to 1972, forms the basis for the fabrication of DICOR glass-ceramics. The properties of this material were modified to develop a biomaterial (see Section 4.4.2). For example, the translucency of the material had to be adjusted to the translucency of natural dental enamel. This objective was fulfilled by reducing the crystalUte size durii the development of DICOR MGC glass-ceramics (Grossman 1989 and Beall 1992). 

The unique feature of DICOR dental restorations include the close match to natural teeth in both hardness and appearance. The glass-ceramic may be accurately cast using a lost-wax technique and conventional dental laboratory investment molds. The high strength and low thermal conductivity of the material provide advantages over conventional metal-ceramic systems. The application of DICOR glass-ceramics as a biomaterial in dentistry is discussed in Section 4.4.2.2. 

Two types of DICOR glass-ceramics are produced for dental applications. The first type is a castable glass-ceramic with which dental restorations are fabricated in the dental laboratory. The second type is a machinable glass-ceramic with which dental restorations are machined using CAD/CAM technology in the dental clinic. 

In 1989, the sintered ceramic DICOR Plus was developed (DICOR Plus 1989). This material allowed dental technicians to create more individually shaded restorations and to mask the cast DICOR glass-ceramic. The heating temperature of this material was 950 C. 

The second type of DICOR glass-ceramic was developed for the purpose of machining dental restorations. This glass-ceramic carries the brand name DICOR MGC. The material is machined using the Cerec 1 system (Siemens AG, Germany). Details of this machining system have been reported by Mormann et al. (1987). 

Bapna M.S., Mueller H.J., and Campbell S.D., "Kinetic Parameters for Crystallization in Dicor Glass," Thermochim Acta, 275, 287-93 (1996). 

Malament K.A. and Socransjky S.S., "Survival of Dicor Glass-Ceramic Dental Restoration Over Fourteen Years" presented at the Academy of Prosthodontics Annual Meetii, Newport Beach, CA. 

Dicor. Tradename. A castable, machineable glass-ceramic based on mica (tetra-silicic fluormica) with up to 7% added Zr02 to improve chemical durability and translucency for dental applications. (P.J. Adair, Dentsply International and Corning Glass. U.S. Pat, 4431420 1984)... 

The microstructure and physical properties of the DICOR MGC glass-ceramic were described by Grossman (1991). The microstructure of DICOR MGC (Corning 9670) is characterized by a high crystallinity of the glass-ceramic. The crystal content is estimated to be approximately... 

Grossman D.G., "Structure and Physical Properties of Dicor/MGC Glass-Ceramic" pp. 103-15 in International Symposium on Computer Restorations. Edited by W.H. Mormann. Quintessence, Chicago, IL, 1991. 

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