Ist Year - Dental Materials

1. All Ceramic Restoration
By
Dr- Tayseer Mohamed

2. All ceramic
restoration
Porcelian fused
to metal
Feldspathic
porcelain
Porcelian baked on
Ceramic crystalline
core.
Porcelain baked on
cast metal framework
Porcelian baked on
platinm foil.
Composed of 90%
amorphous phase.
Used for anterior and
posterior restoration.
Used for anterior and
posterior restoration.
Used only for anterior
crown.
Crystalline phase
provids good strength
and ideal esthetic.
Strong ductile metal
copy withstand high
forces but fracture
and lack good esthetic.
Very brittle if used
posteriorly occlusal
forces subject them to
tensile stress.

3. Ceramic restoration was developed to
over come the dis-advatages of ceramo-
metal restoration as.
1. lack of natural translucency.
2. Bond failure.
It contains about 90 % by volume
crystalline phases as reinforcing agents.

4. Advantages of all ceramic restorations
1. Superior esthetics.
2. High biocompatible because it is inert.
3. Low thermal conductivity: no thermal shock to the
prepared tooth.
4. No electrolytic corrosion.
5. No metal preparation: no metal inhaled during metal
finishing.
6. Excellent bonding between the porcelain veneer and
ceramic coping.
7. No repeated firing: no distortion of infra-structure.
8. Resistant to degradation to oral fluids.

5. All ceramic systems according to various
manufacturing techniques.
1. Sintered all ceramic restoration.
2. Heat pressed all ceramic.
3. Slip cast all ceramic.
4. Machinable all ceramic

6. SINTERED ALL CERAMIC

7. 1. Alumina-based Ceramics:
Alumina has a high modulus of elasticity and
high fracture toughness.
40% stronger than traditional feldspathic
porcelain.
It contains an opaque inner core containing
50% by weight alumina for high strength.
Core is veneered with matched expansion
porcelain due to its inadequate translucency.

8. 2. Leucite-based Ceramics:
• Leucite(45%) in feldspathic porcelain
increases the flexural and compressive
strength.
• The large mismatch in thermal contraction
between leucite and the glass matrix causes
development of compressive stresses in glass
around the crystals so resistance to crack
propagation.

9. Sintered all-ceramic restorations are
now being replaced by heat-pressed
or machined all-ceramic restorations
with better-controlled processing
steps.

11. HEAT PRESSED ALL CERAMIC
1. Leucite- based ceramics .
2. Lithium disilicate based ceramics.

12. Heat-pressing requires a specially designed
automated pressing furnace.
Heat-pressing relies on the application of
external pressure at high temperature to sinter
and shape the ceramic.
Ceramic ingots are brought to high temp in a
phosphate-bonded investment mold produced
by the lost wax technique.
A pressure of 0.3 to 0.4 MPa is then applied
through a refractory plunger. This allows filling
of the mold with the softened ceramic.

13. • Increase in strength can be explained by the
fact that these ceramics possess a higher
crystallinity and that the heat-pressing
process generates an excellent dispersion of
these fine crystals.
• The main disadvantages are the initial cost of
the equipment and relatively low strength
compared with other all-ceramic systems

17. 1. Leucite- based ceramics
Ex: IPS Empress.
This type contains leucite as a major
reinforcing crystalline phase dispersed in
a glassy matrix.
Ceramic ingots are pressed at a higher
temperature (1165°C) into a refractory
mold made by lost wax technique.

18. 2. Lithium disilicate based ceramics
Ex: IPS Empress-2
The major crystalline phase of the core
material is Lithium disilicate.
The material is pressed at 920°C and layered
with a glass containing some dispersed
apatite crystals.
Their translucency is less than leucite-based
ceramics and both have higher translucency
than alumina based ceramics.

19. SLIP CAST ALL CERAMIC MATERIALS
1. In-ceram alumina.
2. In-ceram spinell .
3. In-ceram zirconia.

20. Slip casting technique
• Slip is an aqueous suspension of fine
ceramic particles in water.
• The slip is applied on to a porous
refractory die that absorbs water from
the slip by capillary action and leads to
condensation of slip on the die.

21. The die with the slip are fired at high
temperature.
The die shrinks more than the condensed slip
which allows easy separation after firing.
• The fired porous core is then glass infiltrated (a
process in which molten glass is drawn into the
pores by capillary action at high temperature).

22. • Materials processed by slip-casting tend to
exhibit lower porosity and fewer
processing defects than do traditionally
sintered ceramic materials.
• The strength of In-Ceram is about three to
four times greater than that of earlier
alumina core materials.

23. Slip casting technique
A
B
c

25. a. In-ceram alumina
The alumina content of the slip is more than
90% .
First firing the slip, then porous alumina
coping is infiltrated with glass during a second
firing . This processing leads to a high-
strength material because of the presence of
densely packed alumina particles.
The restoration is veneered using matched-
expansion veneering ceramic.

26. • Because of the high strength of the core,
short-span anterior fixed partial prostheses
can be made using this process. However, the
presence of alumina crystals with a high
refractive index, together with 5% porosity,
account for some degree of opacity in this all-
ceramic system.

27. b. In-ceram spinel
• It contains Magnesium spinel as a major crystalline
phase with traces of alumina.
• Spinel-based slip-cast ceramics are more
translucent, because the spinel phase allows better
sintering, but the flexural strength is slightly lower
than that of the alumina-based system
• It is indicated for anterior crowns, inlays and onlays
.

28. c. In-ceram zirconia
Contains zirconia and alumina.
It has the greatest levels of opacity
and should only be used in posterior
regions as crowns or bridges.
It has the highest flexural strength
among in-ceram types.

29. Machinable all ceramic restorations
• Machinable ceramics can be milled to
form inlays, onlays and veneers using two
systems:
1. CAD/CAM technology .
2. Copy milling .

30. a. CAD/CAM technology . The system refers to
computer aided design/computer aided machining).
The system has an intraoral camera to take an optical
impression of the prepared tooth.
The image is computerized.
The restoration is designed with the aid of a
computer.
Then, the restoration is machined from ceramic blocks
by a computer-controlled milling machine which
takes only few minutes.

31. • Advantages:
1. Obtaining an indirect restoration in one visit
without impression taking or need for temporary
restoration.
2. No need for the dental lab to fabricate the
restoration.
3. No porosity as there is no firing.
• Disadvantages:
1. Expensive equipment.
2. Inadequate marginal inaccuracy .

32. b. COPY MILLED CERAMIC
The primary difference between this and the
earlier system (CAD- CAM) is the manner in
which the tooth dimensions are picked up.
Coy milling scans the object whereas the Cad-
Cam need digital impression.

35. In this system, a hard resin pattern is
fabricated on a traditional stone die.
The pattern is placed in the machine. A tracing
tool passes over the pattern and guides a
milling tool which grinds a copy of the pattern
from a block of ceramic. Then it is veneered
with porcelain and fired to complete the
restoration.