1. CERAMIC
Dental Materials

2. DEFINITIONS
• Ceramic –
• An inorganic compound w/ non metallic
properties typically composed of metallic and
non metallic elements
• Dental ceramic –
• An inorganic compound w/ non metallic
properties typically composed of O2 and 1 or
more metallic or semi metallic elements that is
formulated to produce the whole part of a
ceramic based dental prosthesis

3. 4 categories of ceramics
1. Silicate Ceramics
2. Oxide Ceramics
3. Nonoxide Ceramics
4. Glass Ceramics

4. Silicate Ceramics
• Amorphous glass phase with a porous structure
• Main components:
• SiO2
• Small quantities of :
• Al2O3
• MgO
• ZrO2
Dental porcelain

5. Oxide Ceramics
• Principally contains:
• Al2O3,MgO,ZrO2 with either no glass phase or
small content.

6. Non oxide Ceramics
• Impractical for dental use
• Why?
• High sintering temp
• Unesthetic color
• opacity

7. Glass Ceramics
• Are partially crystallized glass
• Produced by nucleation and growth of crystals
in glass matrix phase

8. Dental ceramics
• May consist primarily of :
• Glasses , glass ceramics or highly crystalline
structures
• Ceramics are more resistant to corrosion than
plastic
• Remain stable for a long period of time
• Do not react with most liquids, gases
• Excellent – fair fracture toughness
• Zirconium dioxide
> Flexural strength similar to steel

9. Dental ceramics
• Biocompatible
• Long term color stabbility
• Wear resistance
• Ability to be formed into precise shapes

10. Phillips Dental Materials
CLASSIFICATION OF DENTAL
CERAMICS

11. Dental ceramics can be classified
according to :
• Use or Indication
- Anterior
- Posterior
- Crowns
- Veneers
- Post and cores
- FPDs
- Stain ceramics
- Glaze ceramics

12. • Composition
- Pure alumina
- Pure zirconia
- Silica glass
- Leucite-based glass ceramic
- Lithia based glass ceramic

13. • Processing method
- Sintering
- Partial sintering
- Glass infiltration
- CAD CAM
- Copy milling

14. • Firing temperature
- Low fusing
- Medium fusing
- High fusing

15. • Microstructure
- Glass
- Crystalline
- Crystal containing glass

16. • Translucency
- Opaque
- Tranlucent
- transparent

17. • Fracture Resistance
• Abrasiveness

18. Metal Ceramic Prosthesis
• COMPOSITION OF DENTAL PORCELAINS
• Most dental porcelains consist of
• Kaolin
• Silica
• Feldspar
• Glasses

20. Glass modifiers
• Manufacturers employ glass modifiers to
produce dental porcelains with different firing
temperatures
Categories Firing temperature
High fusing 1300oC or above
Medium fusing 1101 to 1300oC
Low fusing 850 to 1100oC
Ultra low fusing < 850oC

21. Feldspathic Porcelains
• Feldspar- main ingredient of classical metal
ceramic porcelain. ( crystalline and opaque)
• Chemically designated as K2O.Al2O3.6SiO2
• These ceramics are called porcelains because
they contain a glass matrix and one or more
crystal phases.

22. Other Additives
• B2O3 ( Boric Acid) – behaves like a glass modifier
• Alumina – not a true glass modifier but can alter
softening temperature and viscosity
• Pigmenting oxides – natural shade of tooth
• Iron or nickel oxide – brown
• Copper oxide – green
• Titanium dioxide – yellowish brown
• Manganese oxide – lavander
• Cobalt oxide – blue
• Opacity– zirconium oxide, tin oxide

23. Esthetic potetial
Metal ceramic All Ceramic
• 70% of all fixed restorations • Matches appearance of
• Not the best esthetic choice adjacent natural tooth
• Dark line at facial margin • More susceptible to
fracture
• Ceramic margin

24. Porcelain Condensation
• Supplied as a fine powder to be mixed with water
or another vehicle and condensed into desired
form
• Dense packing has 2 benefits:
1. Lower firing range
2. Less porosity
• Packing may be achieved through
1. Vibration
2. Spatulation
3. Brush technique

25. Drying
• The restoration is placed in an open furnace to
be dried.
• Until 480 deg C is reached
• Drying stage – 5- 8 minutes
• Ensures the remaining water is removed
• Dries too quickly – spontaneous breakage
• If wet structure is placed onto firing in hot
furnace – steam-crumble-explode

26. Sintering of porcelain
• The purpose of firing :
• To sinter the particles of powder together
properly to form the prosthesis.
• Sintering – process of heating closely packed
particles to a specified temp to densify and
strengthen a structure
• After porcelain is preheated, firing cycle is
initiated.

27. Overglazing and shading
• Natural glazed porcelain is much stronger than
ground, rough, non glazed porcelain.
• Glaze – effective in reducing crack propagation
within the outer surface.
• Stains and glazes

28. Cooling of metal-ceramic prosthesis
• Sudden changes in temperature – fracture
• Slow cooling followed by slow opening of
furnace door

29. Benefits and drawbacks of metla
ceramics
• Stronger and more durable than all ceramic
crowns
• Permanent aesthetic quality
• Fracture resistance
• No abrasion wear
• No staining along metal and veneer interface
• Less tooth structure is removed to provide
proper bulk for the crown.

30. Ceramics for Ceramic Metal
Restorations
• 5 requirements:
1. Must simulate appearance of tooth
2. Fuse at low temp
3. Must have compatible thermal expansion
with metals
4. Must withstand oral environment
5. Must not abrade opposing teeth

31. Ceramics for ceramic metal
restorations
• Ceramics are composed of crystalline phases
in an amorphous , glassy vitreous matrix.
• Glass
• They fuse at a lower temp , to prevent metal
from distorting

32. ALL CERAMIC PROSTHESIS

33. • Castable and machinable glass ceramics
• Pressable glass ceramics
• Slip cast All ceramic ceramics
• Procera Allceram
• CAD CAM ceramics

34. GENERAL APPLICATIONS OF
CERAMICS IN DENTISTRY

35. • Ceramics are the best materials to match
esthetic complexity of human teeth
• Used for ceramic metal crown
• FPD
• All ceramic resto
• To fabricate denture teeth

36. Ceramic metal crowns
• ADVANTAGE:
• Better abrasion resistance
• More durable
• Better adhesion with resin cements
• DISADVANTAGES:
• Occlusal adjustment is more difficult
• Not for high stress areas

37. All Ceramic Crowns, inlays , veneers
• Ceramic veneer – layer of ceramic bonded to
the facial surface of a prepared tooth to cover
any defaults.
• Custom made , fabricated in lab.