Mechanical properties

1. MECHANICAL PROPERTIES
1)Brittleness… strong ionic and covalent bond
Their compressive strength is higher than their
tensile strength
(governed by a presence of small flaws or crack)
2) Low fracture toughness
3) Hard

2. SILICA BASED CERAMICS
Vitrification: It is a process of glass forming.
Glass
a product which has been cooled into a rigid condition
without crystallization
(short range arrangement of crystals)
i.e. Vitreous structure or supercooled liquids
Devitrification (Ceraming): it is a process by which
crystallization of glass occurs.
(Nucleating agent at a high temperature for a long time)

3. a ceramic consisting of a glass matrix phase and at
least one crystal phase that is produced by
devitrification.
They have greater hardness & strength
But less translucency
Glass Ceramic

4. Scanning electron micrograph showing the microstructure of
feldspathic porcelain for metal-ceramic restorations

5. DENTAL PORCELAIN
is a group of the ceramic material family
1. Conventional dental porcelain: a glassy
phase and contains a crystalline phase.

6. 1. Recent All- ceramic materials: glass ceramics in
which the crystalline phase is prevalent
DENTAL PORCELAIN

7. USES
1. Denture teeth.
2. Jacket crown.
3. Porcelain fused to metal (ceramo-metallic) for
crown and bridge work.