Dental ceramic restorations

By Dr. Vishaal Bhat on Wednesday 2 July 2008 with 0 comments



Temperature classification:

  1. high fusing (1288-1371C)- used in the fabrication of denture teeth.

  2. medium fusing (1092-1260C)- aluminous porcelain used in the old porcelain jacket crown.

  3. low fusing (871-1066C)- feldspathic porcelain used for ceramo-metal restorations.

The principle components of feldspathic porcelain:

-feldspar: for increased CTE

-quartz (silica): for strength

-kaolin (alumina): acts as a binder

-fluxes (glass modifiers): increases hardness and viscosity. K2O increases CTE firing through the formation of leucite

-leucite: included in porcelains for metal ceramic restorations to elevate their CTE to be compatible with that of casting alloys.

-These components are first fused at a high temperature, forming a frit.

-lLow fusing porcelains are used to fabricate most dental ceramic restorations. The flexural strength of feldspathic porcelain is low (60-70 Mpa). This is one of the reasons why a metal substructure is needed to reinforce the ceramic restoration. This will improve the fracture resistance to about 300-500 Mpa.

-Vitrification: the absence of crystallization on cooling and solidification.

Category: Dental Materials Notes , Prosthodontics Notes

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