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Product Code : 23
Brand Name : Vita VMK
Product Description

VITA VMK Master is a conventional metal ceramic. Optimized manufacturing processes and a new distribution of particle sizes provide the development basis to obtain a product featuring good stability, low shrinkage as well as simple and economic processing for the fabrication of high-quality, esthetic restorations.

The structure of VITA VMK Master consists of two principal constituents: natural potassium (KAISi3O8), orthoclase and sodium bicarbonate feldspars (NaAISi3O; albite) constitute the largest proportions and are frequently referred to as tectosilicates in literature since they form three-dimensional networks in the veneering ceramic. Potassium feldspar, which is essential for manufacturing the VITA ceramics, helps to achieve ideal abrasion on the antagonist tooth and chemical stability for the oral system.

Orthoclase melts incongruently, i.e. melt and solid reveal different compositions. When using this type of feldspar, a melt is obtained which forms the glass phase and the leucite (KAISi2O6) during solidification.

Leucite represents the crystalline phase of the VMK materials and is essential for the ceramic materials in two respects: on the one hand, it ensures the stability, i.e. it guarantees that the shape of firing object remains unchanged even at high temperatures. On the other hand, the coefficient of thermal expansion (CTE) of the veneering ceramic is controlled by the proportion of leucite. Moreover the crystals cause increased strength of the veneer and reduce crack propagation.

With 15 - 25 %, quartz is another main constituent and is added to increase the proportion of the glass phase and hence the traslucency.

Metal oxides are also added to the veneering ceramics to optimize the optical properties. Accordingly, metal oxides are used as opacifiers and thus the translucency and the opalescence are adjusted. In addition to the metal oxides, pigments are added to the VITA metal ceramics, which are produced in a special fritting process; these pigments are not burned and remain unchanged over the years but determine the final shade of the fired ceramic and thus provide the restoration with long-term shade stability.

Physical properties

Unit of measure

Value

CTE (25 - 500°C) - OPAQUE

10-6 · K-1

13,6 -14,0

Softening point - OPAQUE

oC

approx. 670

Transformation point - OPAQUE

oC

approx. 575

CTE (25 - 500°C) - DENTINE

10-6 · K-1

13,2 -13,7

Softening point - DENTINE

oC

approx. 660

Transformation point -DENTINE

oC

approx. 565

Solubility - DENTINE

µg/cm2

<10

3-point flexural strength -DENTINE

MPa

approx. 90

Average particle size - DENTINE

µm

approx. 19

Adhesive bond

MPa

> 50

Density - DENTINE

g/cm3

approx. 2,4

Physical properties :

In addition to excellent bonding to metal and perfect thermal stability, VITA VMK MASTER features extremely low solubility in acids. Moreover, compared to materials of competitors and the ISO limit according to ISO 6872, VITA VMK MASTER exhibits outstanding flexural strength values.

Indication

  • metal-ceramic full veneers
  • metal-ceramic partial veneers

Contraindication

Bruxism

Firing temperature

When using dental ceramics, the firing result largely depends on the individual firing procedure and the substructure design of the user. The type of furnace, the location of the temperature sensor, the firing tray as well as the size of the object during the firing cycles are essential factors for the quality of the firing result. Our application-technical recommendations (regardless whether they have been provided orally, in writing or in the form of practical instructions) are based on extensive experience and tests. The user, however, should consider this information only to provide basic values. If surface, transparency and degree of gloss should not correspond to the firing result that is achieved under optimal conditions, the firing procedure must be adjusted correspondingly. The crucial factors for the firing procedure are not the firing temperature displayed by the furnace but the appearance and the surface condition of the ceramic after the firing process.

General information :

  • A chamfer or shoulder with rounded inner angle should be prepared for crowns.
  • The aim should be a circumferential cutting depth of one millimeter.
  • The vertical preparation angle should be at least 3o.
  • All transitions from the axial to the occlusal or incisal surfaces should be rounded. Uniform and smooth surfaces are recommended.

Shoulder preparation or chamfer preparation

Tangential preparation - contraindicated for ceramic shoulders

Incorrect chamfer preparation - generally contraindicated


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