Ceramics for Dental Restorations , Ceramic-Metal Restorations ,All-CeramicRestorations dental material

1. Ceramics for Dental
Restorations

2. Definitions
• The term Ceramic is defined as any product
made essentially from a nonmetallic material
by firing at a high temperature to achieve
desirable properties
• The term Porcelain refers to a family of
ceramic materials composed essentially of
Kaolin, Quartz, and Feldspar, also fired at
high temperature

3. Classification of
Dental Ceramics

4. Classification of Dental Ceramics
Dental ceramics can be classified according to:
1. Fusion Temperature
2. Application
3. Fabrication Technique
4. Crystalline Phase

5. 1. Fusion Temperature
Fusion temperature can be classified to:
1. High-fusing ceramics (1315° to 1370° C)
2. Medium-fusing ceramics (1090° to 1260° C)
3. Low-fusing ceramics (870° to 1065° C)
4. Ultra-low-fusing ceramics (below 870° C)

6. 1. Fusion Temperature
• The medium- and high-fusing ceramics are
used for denture teeth
• Dental ceramics for ceramic-metal or all-
ceramic fixed restorations belong to the low-
or medium-fusing categories

7. 2. Application
Ceramics have three major applications in
dentistry:
1. Ceramics for metal crowns and fixed partial
dentures
2. All-ceramic crowns, inlays, onlays, and
veneers, when esthetics is a priority
3. Ceramic denture teeth

8. Dental Crowns

9. 3. Fabrication Technique

10. 3. Fabrication Technique
• One of the most common fabrication
techniques for dental ceramics is called
Sintering
• Sintering is the process of heating the
ceramic to ensure densification. This occurs
by viscous flow when the firing temperature
is reached

11. 4. Crystalline Phase
• After firing, dental ceramics are composed of two
phases: a glassy (or vitreous) phase surrounding a
crystalline phase
• Increasing the amount of glassy phase lowers the
resistance to crack propagation but increases
translucency
• Materials for all-ceramic restorations have
increased amounts of crystalline phase (between
35% and 90%) for better mechanical properties

12. Ceramic-Metal Restorations
(or)
Porcelain Fused to Metal (PFM)

13. Ceramic-Metal Restorations
Ceramic-metal restorations consist of:
1. Cast metallic framework (or core)
2. Opaque layer, consisting of ceramic rich in
opacifying oxides (esthetics & bond)
3. Dentin and enamel ceramics (translucent)

14. Ceramic-Metal Restorations

15. Ceramic-Metal Restorations
Composition:
1. In its mineral state, feldspar, the main raw ingredient of
dental porcelains, is crystalline and opaque with an
indefinite color between gray and pink. Chemically it is
designated as Potassium Aluminum Silicate, with a
composition of K2O . Al2O3 . 6SiO2. The fusion
temperature of feldspar varies between 1125° & 1170° C,
depending on its purity

16. Ceramic-Metal Restorations
Composition:
2. Pure Quartz (SiO2) crystals are used in dental porcelain
and ground to the finest grain size possible. Silica is
added, and contributes stability to the mass during
heating by providing a glassy framework for the other
ingredients

17. Ceramic-Metal Restorations
Manufacture:
1. Feldspathic dental porcelains in recent years
are made mainly with potash feldspar (K2O,
Al2O3, 6SiO2) and small additions of Quartz
(SiO2)

18. Ceramic-Metal Restorations
Manufacture:
2. After the manufacturing process is
completed, feldspathic dental porcelain
consists of two phases. One is the vitreous
(or glass) phase, and the other is the
crystalline (or mineral) phase

19. Ceramic-Metal Restorations
Processing:
1. Porcelain Application & Condensation
2. Drying
3. Firing/Sintering
4. Glazing
5. Cooling

20. Ceramic-Metal Restorations

21. Ceramic-Metal Restorations

22. Ceramic-Metal Restorations

23. Ceramic-Metal Restorations

24. All-Ceramic
Restorations

25. All-Ceramic Restorations

26. All-Ceramic Restorations
Several processing techniques are available for
fabricating all-ceramic crowns:
1. Sintering
2. Heat-pressing
3. Slip-casting
4. Machining

27. All-Ceramic Restorations
1. Sintering:
Two main types of all-ceramic materials are
available for the sintering technique:
A. Alumina-based ceramic
B. Leucite-reinforced ceramic

28. All-Ceramic Restorations
1. Sintering:
A. Alumina-based ceramic:
• Aluminous core ceramic is a typical example of
strengthening by dispersion of a crystalline phase.
Alumina has a high modulus of elasticity (350 GPa) and
high fracture toughness (3.5 to 4 MPa . m 0.5)
• Aluminous core porcelains have flexural strengths of
about 138 MPa and shear strengths of 145 MPa

29. All-Ceramic Restorations
1. Sintering:
B. Leucite-reinforced ceramic:
• Leucite acts as a reinforcing phase; the greater leucite
content (compared with conventional feldspathic
porcelain for ceramic-metal applications) leads to
higher flexural strength (104 MPa) and compressive
strength

30. All-Ceramic Restorations
2. Heat-pressed:
• Heat-pressing relies on the application of external
pressure to sinter and shape the ceramic at high
temperature. Heat-pressing is also called high-
temperature injection molding. The advantages of heat-
pressed ceramics include good esthetics, high strength
(but higher opacity). Processing times are short and
margin accuracy is within an acceptable range

31. 2. Heat-pressed

32. All-Ceramic Restorations
3. Slip-casting:
• Slip-casting involves the condensation of an aqueous
porcelain slip on a refractory die
• Materials processed by slip-casting tend to exhibit
reduced porosity, fewer defects from processing, and
higher toughness than conventional feldspathic
porcelains

33. 3. Slip-casting

34. All-Ceramic Restorations
4. Machinable:
• Machinable ceramics can be milled to form inlays,
onlays, and veneers using special equipment. One
system uses CAD/CAM (computer assisted
design/computer assisted machining) technology to
produce restorations in one office visit

35. 4. Machinable

36. General Applications
of Ceramics in
Restorative Dentistry

37. Veneer

38. Inlay

39. Onlay

40. Thank you