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POTTERY IN EUROPE
CLAY
SAND
GROUND SEASHELLS
VOIDS---CLAY---FIRING
BEATING ( WEDGING )
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SINTERING
The conversion of clay from a mass of individual particles
loosely held together by a water binder to a coherent...
KILN
UP-DRAUGHT KILN
EARLY KILNS---900 ۫C---pottery fired at this
temperature is known as EARTHENWARE---
higher kiln tempe...
CHINESE PORCELAIN
10 Century AD
Ceramic technology in China was so advanced to such a
stage that they were able to produce...
The dental application of porcelain dates from 1774,when a
French apothecary named Alexis Duchateau considered the
possibi...
MILE STONES AND PIONEERSMILE STONES AND PIONEERS
 700 BC: ETRUSCANS
 1774 DUCHATEAU.
 1789 DE CHEMANT
 1808 FRONZI
 1...
 1965 MCLEAN and HUGHES
 1980 CEREC 1,2 and 3
 1984 ADAIR and GROSSMAN
 1990 PRESSABLE GLASS CERAMIC
 1992 DUCERAM LF...
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The term ceramics is derived from the Greek word
‘keramos’ meaning ‘potter’s clay’/ burnt stuff.
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CERAMIC: defined as inorganic compound with
nonmetallic properties consisting of metallic or semi
metallic elements.
PORCE...
 PREDOMINANTLY
GLASSY MATERIAL.
 Amorphous.
 Derived from feldspar.
 Resistant to
devitrification long
firing range.
...
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CLASSIFICATION OF DENTAL
CERAMICS
 USE
 COMPOSITION
 PROCESSING METHOD
 FIRING TEMPERATURE
 MICROSTRUCTURE
 TRANSLUC...
FABRICATION CRYSTALLINE
PHASE
ALL
CERAMIC
MACHINED Al, feldspar, mica
SLIP CAST Al, spinel
HEAT PRESSED Leucite ,lithium
d...
CLASSIFICATION OF CERAMICS
By content:
Regular feldspathic porcelain
Aluminous porcelain
Leucite reinforced porcelain.
Gla...
By use:
 Denture teeth
 Metal ceramic
 Veneers, inlays, crowns, anterior bridges
By processing method:
Sintering
Castin...
By their firing temperature
High fusing -1300°C
Medium fusing ---1100 - 1300° C
Low fusing--850 - 1100°
Ultralow fusing < ...
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By their area of application:
Opaque porcelain
Body dentine porcelain
Gingival dentin porcelain
Overlay enamel
Incisal ena...
Basic composition
 Feldspar: Mixture of potassium and aluminium silicates
Two important properties
-retains its form
-inc...
COMPOSITION
In dentistry porcelain were initially used for the fabrication of
the denture teeth.
Denture teeth porcelain: ...
Conventional dental porcelain is a ceramic based on a
network of silica (Si) and potash feldspar or Soda feldspar
or both....
Silica
It is a polymorphic material and can exist in 4 different
forms.
 Crystalline quartz
 Crystalline cristobalite
 ...
Fused silica is a high melting material its high meltingFused silica is a high melting material its high melting
temperatu...
The vitreous matrix is made of silicate glass.
Silica which is a prototype of glass forming
oxides ion is small and highly...
Alumina silicate glass
The aluminum can replace the silicone ions and this results in
the formation of Aluminosilicate gla...
Fluxes
Potassium, sodium and calcium oxides are used as glass
modifiers and act as fluxes by interrupting the integrity of...
So the silica tetrahedra thus obtained are able to move
more easily at lower temperature than the earlier
network.
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Intermediate oxides
The addition of glass modifiers and fluxes not only
lowers the softening point but also decreases the
...
Each aluminum has a charge of +3 as compared with a
charge of +4 of silicon ion, hence an additional unit
positive charge ...
Other additions of dental porcelain
Pigmented oxides are added to obtain various shades
needed. These coloring pigments ar...
Devitrification and thermal expansion
vitrification refers to the development of a liquid phase by
reaction / melting whic...
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This is usually associated with high expansion glasses
where more amounts of alkalis, like soda (Na are seen. By
contrast ...
Coloring and opacifying dental porcelain
The addition of concentrated color frits to dental
porcelain is insufficient to p...
Common oxides used are:
1. Cerium oxide
2. Titanium oxide
3. Zirconium oxide (the most popular opalcyfying agent
used) Pot...
When feldspar is heated at temperatures between 1530 and
1560 degree centigrade, it undergoes incongruent melting
to form ...
Fritting:
The term frit is used to describe the final glass product. The
raw mineral powders are mixed together in a refra...
GENERAL PROPERTIES OF CERAMICS
Biological properties:
These are inert materials with excellent biocompatibility.
Chemical ...
Mechanical properties:
Hardness of ceramics for dental application should be
similar to enamel, as it is desirable to mini...
Thermal properties:
These are insulating materials as a result though when the
metal is electrically / thermally stimulate...
Optical properties:
Excellent optical properties dental porcelains are translucent
because there are no free electrons and...
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STRENGTH OF PORCELAINS :
These materials usually fall to show the strength of 2 Gpa
which they are supposed to show theore...
A phenomenon known as stress concentration at the
tips of these minute scratches/ flames causes the
localized stress to in...
As the crack propagates through the material the stress
concentration is maintained at the crack tip until the
crack moves...
Static fatigue:
Exposure to water reduces the strength the porcelain
causing delayed failure. Delayed failure in glasses h...
Water reacts with glass destroying the Si - o network and hydroxyl
ions attach the siloxane bonds of the network.
OH+ R—Si...
METHODS OF STRENGTHENING PORCELAIN
The principal deficiencies faced by ceramics are -
brittleness, low fracture toughness ...
Method of strengthening materials: In the oral
environment tensile stresses are usually created by
bending forces, and the...
1.Development of residual compressive stresses within
the surface of the material.
2. Interruption of crack propagation th...
Strength is gained by virtue of the fact that the residual
stresses developed must first be negated by the
developing tens...
a. ion exchange mechanism:
This technique is called as chemical tempering and is
the most sophisticated and effective way ...
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The squeezing of the potassium ion into place
formerly occupied by sodium ion creates large
residual compressive stresses ...
The technique is as follows:
Characterize the finished crown and adjust the
occlusion.
Place the crown into a mould of ana...
Place the container in a cool furnace and raise the
temperature slowly to 500°C
Hold the temperature at 500 C for 6 hours....
Remove the crown from the furnace and cool to room
temperature. *Further more it was observed that
grinding this crown by ...
Furthermore contact with acidulated phosphate fluoride
for over 3 hours removes most of the ion exchange layer
and not all...
b. Thermal tempering:
This is the most common method of strengthening
glass. This creates residual surface compressive str...
The pull of the solidifying molten core as it shrinks,
creates residual tensile stresses in the core and residual
compress...
While doing porcelain fused to metal restorations the
metal should be selected such that it contracts slightly
more (highe...
Disruption of crack propagation
This can be categorized into 3 types:
1. Crack tip interactions
2. Crack tip shielding
3. ...
Crack tip interactions:
These occur when obstacles in the microstructure
act to improve crack motion.
These obstacles are ...
When the crack is deflected out of plane the crack is no
longer subjected to pure tensile stresses and will
involve some s...
Crack tip shielding:
This results when events are triggered by high stresses in the
crack tip region that acts to reduce t...
In toughened ceramic the high temperature phase of
zirconia is constrained at room temperature. Applied
tensile stress wor...
Microcrack toughening:
It has been theorized that the high coefficient of
thermal contraction and volume reduction associa...
Compressive forces are created in the glass matrix
surrounding the particles leading to microcracking in
the leucite phase...
Crack tip bridging:
This it the third strengthening mechanism that has
been proposed. It occurs when a second phase acts a...
The fibers act as ligaments which make it more difficult
to open the crack at an applied stress.
Methods of designing comp...
Minimizing tensile stresses:
When porcelain is fired onto a rigid material the shape
of the metal will influence the stres...
For partial metal coverage the junction between the
metal coverage the junction between the metal and
porcelain is therefo...
Reducing stress raisers;
Stress raisers are discontinuities in ceramic structures
in brittle materials that cause stress c...
Notches caused in the porcelain due to the folds of the
underlying platinum foil substrate. Sharp line angle in
the prepar...
TECHNIQUE INVOLVED IN FABRICATING
PORCELAIN FUSED TO METAL
There are 2 basic methods of fabricating porcelain
fused to met...
Platinum foil technique:
This technique involves fabrication on either a single
platinum foil or a double platinum foil.
F...
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Fabrication using a double foil matrix technique: Here
a second layer of platinum foil is swaged on the first
and cut back...
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Swaged gold alloy foil capping:
A laminated gold foil supplied in fluted shape is
also used as an alternative to the cast ...
Supporting the porcelain of a metal foundation
The various alloys that can be used are
High noble.
- Gold platinum palladi...
Noble:
- Palladium silver
-High palladium
They have less than 25% noble metal content
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Predominantly base metals:
- Nickel chromium
- Nickel chromium
- Cobalt beryllium
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BONDING MECHANISMS
Four mechanism have been described to explain
the bond between the ceramic veneer and the metal
substru...
Mechanical entrapment:
This creates attachment by interlocking the ceramic
into the microabrasions on the surface of the m...
Compressive forces:
These are developed by a properly designed
coping and a slightly higher coefficient of thermal
expansi...
Vander waals forces
It is an affinity based on a mutual attraction of
charged molecules. They are minor force for
bonding....
Bonding of porcelain to metal using electrodeposition:
A layer of pure gold is deposited onto the cast metal,
followed by ...
The advantages of this methods are:
1. Bonding is improved because of improved
wetting the metal by the porcelain and redu...
3. The gold color of the oxide film improves the vitality
and esthetics of porcelain, when compared to the normal
dark oxi...
Classification of bond failures in metal ceramics:
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Metal porcelain: Fracture leaves a clean surface of
metal. Seen when metal surface is devoid of
oxides. May also be due to...
Metal-metal oxide:
Metal oxide breaks away from the metal and is left
attached to the porcelain seen commonly in base
meta...
Alloy surface treatment:
Once the coping in made proper finishing with
aluminium oxide strips is done to remove any
surfac...
Heat treatment:
The coping is placed in a furnace at relatively low
temperature and is then raised slowly to about
1000°C ...
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 ThicknessThickness::
 Cleaning :Cleaning :
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OxidizingOxidizing
Controlled oxide layerControlled oxide layer
should be created .should be created .
OPAQUE LAYEROPAQUE...
Methods of condensation:
The Porcelain is mixed and applied.
Vibration:
Mild vibrations are used to densely pack the wet p...
Spatulation:
A small spatula is used, to apply and smoothen the wet
porcelain. This action brings excess water to the surf...
METHODS OF BUILDING AND CONDENSING
PORCELAIN
The porcelain is usually built to shape using a liquid
binder to hold the par...
Types of binders:
Distilled water: Is the most popular binder used in
dentin and enamel porcelain.
Propylene glycol: Used ...
Building porcelain:
1 The powder is mixed on a glass slab.
2. The mix should not be overstored to avoid the
incorporation ...
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Firing dental porcelain:
After the condensation and building of a crown it is fired
to high density and correct form. Init...
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At this stage the green porcelain is introduced into
the hot zone of the furnace and the firing starts, the
glass particle...
This allows the air/gas bubbles to escape via the grain
boundaries. Sealing the surface by quick firing arrests
the proces...
Do not prolong vacuum firing as by then the surface
skin is sealed and further application of vacuum can
cause surface bli...
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Classification of the stages in Maturity:
Low Bisque:
The surface of the porcelain is very porous and will
easily absorb a...
Medium bisque:
The surface will still be slightly porous but the flow
of the glass grains will have increased. A definite
...
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Cooling
Must be carried out slowly and uniformly. If
shrinkage is not uniform it causes cracking and loss of
strength.
Gla...
The glazing should be done only on a slightly
roughened surface and never should be applied on
glazed surfaces.
1. Overgla...
Over glaze:
These are ceramic powders containing more
amount of glass modifiers thus lowering fusion
temperature. It may b...
Add on porcelains
The add on porcelains are made from similar
materials to glaze porcelain except for the addition
of opac...
Repair of fracture ceramic restoration
Roughen the fracture ceramic surface using an
intraoral sand blaster generally usin...
Aluminous porcelain:
There were developed by Mc Lean in 1965. Its
composition is similar to that of conventional
porcelain...
These are used to construct the core layer for
PJC. These are considered to provide crowns
more esthetics than metal ceram...
These are moreover less expensive than metal
ceramic crowns. But the disadvantage of this
material is the addition of alum...
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Since the introduction of the first successful
porcelain fused to metal in the early 1960’s there
has been an increasing d...
However, this meta substrate can affect the
esthetics of porcelain by decreasing the light
transmission and by creating me...
The evolution of ceramic materials has been a battle for
the ideal strength, aesthetic combination.
The first all ceramic ...
These materials are composed of feldspathic
porcelain to which approximately 50% aluminium
oxide is added to increase the ...
Classification of all ceramic systems:
i. Conventional powder and slurry ceramics
ii. Castable ceramics
iii. Machinable ce...
ALUMINOUS CORE CERAMICSALUMINOUS CORE CERAMICS
 Mclean and Hughes 1965.Mclean and Hughes 1965.
 Alumina content 40-55%.A...
Strength twice that of conventional porcelain sufficient to
use in anterior teeth but is considered inadequate to use in
p...
CASTABLE GLASS CERAMICSCASTABLE GLASS CERAMICS
 DICORDICOR: By Corning glass works and marketed by: By Corning glass work...
 Good esthetics --- chameleon effectGood esthetics --- chameleon effect
 55% tetrasilicic fluoromica crystals.55% tetras...
Ceramming increases strength, toughness, increasesCeramming increases strength, toughness, increases
resistance to abrasio...
 DICOR MGCDICOR MGC
 70% TETRASILICIC FLUROMICA CRYSTAL.70% TETRASILICIC FLUROMICA CRYSTAL.
 Particle size 1-5 microns,...
 Dicor plus : pigmented feldspathic porcelainDicor plus : pigmented feldspathic porcelain
veneer.veneer.
 Willis glass :...
PRESSABLE GLASS CERAMICPRESSABLE GLASS CERAMIC
 MacCulloch in 1968MacCulloch in 1968
 Type of Feldspathic porcelainType ...
SLIP CAST CERAMICSSLIP CAST CERAMICS
 SLURRY OF MATERIAL IS SLIP CAST ON THE DIE ANDSLURRY OF MATERIAL IS SLIP CAST ON TH...
ceramicceramic CeramicCeramic
typetype
CeramicCeramic
veneerveneer
IndicationsIndications FlexuralFlexural
strengthstrengt...
Fabrication stepsFabrication steps
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REFERENCES
1. Science of dental materials- K J Anusavice
2. Restorative dental materials - R G Craig
3. Dental biomaterial...
Evolution of dental ceramics in twentieth century-J W McLean, J Prosthet Dent
2001,85(1),61-66.
Future ceramic systems -J ...
Thank you
For more details please visit
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dental ceramics. / academy of fixed orthodontics

  1. 1. www.indiandentalacademy.com
  2. 2. www.indiandentalacademy.com
  3. 3. www.indiandentalacademy.com
  4. 4. www.indiandentalacademy.com
  5. 5. POTTERY IN EUROPE CLAY SAND GROUND SEASHELLS VOIDS---CLAY---FIRING BEATING ( WEDGING ) www.indiandentalacademy.com
  6. 6. www.indiandentalacademy.com
  7. 7. www.indiandentalacademy.com
  8. 8. www.indiandentalacademy.com
  9. 9. www.indiandentalacademy.com
  10. 10. www.indiandentalacademy.com
  11. 11. www.indiandentalacademy.com
  12. 12. www.indiandentalacademy.com
  13. 13. www.indiandentalacademy.com
  14. 14. www.indiandentalacademy.com
  15. 15. www.indiandentalacademy.com
  16. 16. www.indiandentalacademy.com
  17. 17. SINTERING The conversion of clay from a mass of individual particles loosely held together by a water binder to a coherent solid relies on a process known as SINTERING. In this process, the points at which the individual particles are in Contact fuse at sufficiently high temperatures. www.indiandentalacademy.com
  18. 18. KILN UP-DRAUGHT KILN EARLY KILNS---900 ۫C---pottery fired at this temperature is known as EARTHENWARE--- higher kiln temperatures---impervious pottery---STONEWARE. www.indiandentalacademy.com
  19. 19. CHINESE PORCELAIN 10 Century AD Ceramic technology in China was so advanced to such a stage that they were able to produce: ‘A ceramic so white that it was comparable only to snow, so strong that vessels needed walls only 2-3 mm thick and consequently light could shine through it. So continuous was the internal structure that a dish ,if lightly struck would ring like a bell’ www.indiandentalacademy.com
  20. 20. The dental application of porcelain dates from 1774,when a French apothecary named Alexis Duchateau considered the possibility of replacing his ivory dentures with porcelain www.indiandentalacademy.com
  21. 21. MILE STONES AND PIONEERSMILE STONES AND PIONEERS  700 BC: ETRUSCANS  1774 DUCHATEAU.  1789 DE CHEMANT  1808 FRONZI  1817 PLANTEAU  1825 STOCKTON  1903 Dr.CHARLES LAND  1962 WEINSTEIN and WEINSTEIN  1962 WEINSTEIN et al  1963 VITA ZAHNFABRIK www.indiandentalacademy.comwww.indiandentalacademy.com
  22. 22.  1965 MCLEAN and HUGHES  1980 CEREC 1,2 and 3  1984 ADAIR and GROSSMAN  1990 PRESSABLE GLASS CERAMIC  1992 DUCERAM LFC……. www.indiandentalacademy.comwww.indiandentalacademy.com
  23. 23. www.indiandentalacademy.com
  24. 24. The term ceramics is derived from the Greek word ‘keramos’ meaning ‘potter’s clay’/ burnt stuff. www.indiandentalacademy.com
  25. 25. CERAMIC: defined as inorganic compound with nonmetallic properties consisting of metallic or semi metallic elements. PORCELAIN: refers to a family of ceramic materials composed essentially of kaolin ,quartz, feldspar also fired at high temperature. www.indiandentalacademy.comwww.indiandentalacademy.com
  26. 26.  PREDOMINANTLY GLASSY MATERIAL.  Amorphous.  Derived from feldspar.  Resistant to devitrification long firing range.  Biocompatible  3D network. www.indiandentalacademy.comwww.indiandentalacademy.com
  27. 27. www.indiandentalacademy.comwww.indiandentalacademy.com
  28. 28. CLASSIFICATION OF DENTAL CERAMICS  USE  COMPOSITION  PROCESSING METHOD  FIRING TEMPERATURE  MICROSTRUCTURE  TRANSLUCENCY www.indiandentalacademy.comwww.indiandentalacademy.com
  29. 29. FABRICATION CRYSTALLINE PHASE ALL CERAMIC MACHINED Al, feldspar, mica SLIP CAST Al, spinel HEAT PRESSED Leucite ,lithium disilicate SINTERED Al, Leucite CERAMIC METAL SINTERED Leucite DENTURE TEETH MANUFACTURED feldspar www.indiandentalacademy.comwww.indiandentalacademy.com
  30. 30. CLASSIFICATION OF CERAMICS By content: Regular feldspathic porcelain Aluminous porcelain Leucite reinforced porcelain. Glass infiltrated alumina Glass infiltered spinel All ceramic www.indiandentalacademy.com
  31. 31. By use:  Denture teeth  Metal ceramic  Veneers, inlays, crowns, anterior bridges By processing method: Sintering Casting Machining www.indiandentalacademy.com
  32. 32. By their firing temperature High fusing -1300°C Medium fusing ---1100 - 1300° C Low fusing--850 - 1100° Ultralow fusing < 850 °C Air fired i.e. at atmospheric pressure Vacuum fired i.e. at reduced pressure. www.indiandentalacademy.com
  33. 33. www.indiandentalacademy.com
  34. 34. By their area of application: Opaque porcelain Body dentine porcelain Gingival dentin porcelain Overlay enamel Incisal enamel www.indiandentalacademy.com
  35. 35. Basic composition  Feldspar: Mixture of potassium and aluminium silicates Two important properties -retains its form -incongruent melting  Kaolin (china clay) : hydrated aluminium silicate  Silica (in the form of quartz, and remains as a fine dispersion after firing)  Aluminum oxide www.indiandentalacademy.comwww.indiandentalacademy.com
  36. 36. COMPOSITION In dentistry porcelain were initially used for the fabrication of the denture teeth. Denture teeth porcelain: Mix of powders of feldspar, clay and quartz. This is also referred to as high temperature porcelain. Feldspathic porcelains: These have been in use for more than 50 years. The feldspathic porcelains are too weak to use as all ceramic restorations and hence are supported with a metal coping. www.indiandentalacademy.com
  37. 37. Conventional dental porcelain is a ceramic based on a network of silica (Si) and potash feldspar or Soda feldspar or both. Pigments opacifiers and glasses are added to control the fusion temperature, sintering temperature, thermal contraction coefficient and solubility. www.indiandentalacademy.com
  38. 38. Silica It is a polymorphic material and can exist in 4 different forms.  Crystalline quartz  Crystalline cristobalite  Crystalline tridymite  Non crystalline fused silica www.indiandentalacademy.com
  39. 39. Fused silica is a high melting material its high meltingFused silica is a high melting material its high melting temperature is attributed to the 3 dimensional network oftemperature is attributed to the 3 dimensional network of covalent bonds between the silica tetrahedra which is thecovalent bonds between the silica tetrahedra which is the basic structure for the glass network.basic structure for the glass network. www.indiandentalacademy.com
  40. 40. The vitreous matrix is made of silicate glass. Silica which is a prototype of glass forming oxides ion is small and highly charged and fills the space between oxygen atoms. The tetrahedra must permit sharing of oxygen atoms to permit the formation of silica groups thus resulting in polymerization and a three dimensional network. www.indiandentalacademy.com
  41. 41. Alumina silicate glass The aluminum can replace the silicone ions and this results in the formation of Aluminosilicate glass. Because of the sharing of the oxygen ions the glass containing silicatetrahedra and aluminium tetrahedra polymerises. www.indiandentalacademy.com
  42. 42. Fluxes Potassium, sodium and calcium oxides are used as glass modifiers and act as fluxes by interrupting the integrity of the silicone network. The purpose of a flux is principally to lower the softening temperature of a glass by reducing the amount of cross linking between the oxygen and glass forming elements when soda is introduced instead as bridging the atoms together, it contributes a oxygen atom which acts a non bridging oxygen and as a result a gap is produced in the silicone network. www.indiandentalacademy.com
  43. 43. So the silica tetrahedra thus obtained are able to move more easily at lower temperature than the earlier network. www.indiandentalacademy.com
  44. 44. Intermediate oxides The addition of glass modifiers and fluxes not only lowers the softening point but also decreases the viscosity. Dental porcelains requires a high viscosity as well as low firing temperature. This is done by using intermediate, oxides like Al2O3 can replace the Sio4 tetrahedra. www.indiandentalacademy.com
  45. 45. Each aluminum has a charge of +3 as compared with a charge of +4 of silicon ion, hence an additional unit positive charge must be present to neutralize the negatively charged aluminum ions. So the Na+ ions get attracted to the Al. Boric oxides can also be used in a similar way as aluminum oxide. www.indiandentalacademy.com
  46. 46. Other additions of dental porcelain Pigmented oxides are added to obtain various shades needed. These coloring pigments are produced by fusing metallic oxide together with fine glass and feldspar. These powders are then blended with the unpigmented powders frit to provide the proper hue and chroma for eg. Iron / nickel oxides (brown), copper oxide (green), titanium oxide (yellowish brown), cobalt oxide (blue). www.indiandentalacademy.com
  47. 47. Devitrification and thermal expansion vitrification refers to the development of a liquid phase by reaction / melting which on cooling provides a glassy phase. This structure is termed /vitreous/ when too many silicone tetrahedra are disrupted the glass may crystallize / devitrify. www.indiandentalacademy.com
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  49. 49. This is usually associated with high expansion glasses where more amounts of alkalis, like soda (Na are seen. By contrast less devitrifica is observed in aluminous porcelain as they contain much less soda devitrification may be seen when cloudiness develop in the porcelain which can be accentuated by repeated firings. www.indiandentalacademy.com
  50. 50. Coloring and opacifying dental porcelain The addition of concentrated color frits to dental porcelain is insufficient to produce life like tooth effect since the translucency of porcelain is too high. An opacifying agent generally consists of a metal oxide ceramic to a very fine particle size. www.indiandentalacademy.com
  51. 51. Common oxides used are: 1. Cerium oxide 2. Titanium oxide 3. Zirconium oxide (the most popular opalcyfying agent used) Potassium and sodium feldspar is naturally occurring minerals composed of potash soda, alumina, and silica. It is used in the preparation of dental porcelains designed for metal ceramic crowns. www.indiandentalacademy.com
  52. 52. When feldspar is heated at temperatures between 1530 and 1560 degree centigrade, it undergoes incongruent melting to form crystals as leucite in a liquid phase. Incongruent melting is the process by which one material melts to forms a liquid plus a different crystalline material. This crystalline phase formed is lecture, which is potassium aluminum silicate with a large coefficient of thermal expansion. www.indiandentalacademy.com
  53. 53. Fritting: The term frit is used to describe the final glass product. The raw mineral powders are mixed together in a refractory crucible and heated to a temperature well above their ultimate maturing temperature. The oxides melt together to forma molten glass, gases are allowed to escape and the melt is then quenched in water. The red hot glass striking the cold water immediately breaks up into fragments and this is termed as ‘frit’. www.indiandentalacademy.com
  54. 54. GENERAL PROPERTIES OF CERAMICS Biological properties: These are inert materials with excellent biocompatibility. Chemical properties: The greatest advantage of this material is the extreme resistance offered to attach by chemicals. Chemicals such as hydrofluoric acid are required to dissolve ceramics. As ceramics are inert obtaining adhesion to them is difficult, ceramic restorations are roughened by etching with hydrofluoric acid / by sand blasting to improve the retention of a cement to the internal surface of the restorations. www.indiandentalacademy.com
  55. 55. Mechanical properties: Hardness of ceramics for dental application should be similar to enamel, as it is desirable to minimize the wear of the ceramics restorations and simultaneously to reduce the wear damage of enamel by the ceramic restorations. - Low tensile strength - Exhibits little amount of plastic deformation -Impact resistance is low -They have a good compressive strength. The susceptibility to brittle fracture is a drawback particularly when flow and tensile stress co exist in the same region of the restoration. www.indiandentalacademy.com
  56. 56. Thermal properties: These are insulating materials as a result though when the metal is electrically / thermally stimulated the outermost electrons are transferred to the ceramic thus stabilizing it. www.indiandentalacademy.com
  57. 57. Optical properties: Excellent optical properties dental porcelains are translucent because there are no free electrons and can be colored by pigments such as metallic oxides to match the shade of teeth. Presence of crystalline inclusions have a marked opacifying effect. www.indiandentalacademy.com
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  63. 63. STRENGTH OF PORCELAINS : These materials usually fall to show the strength of 2 Gpa which they are supposed to show theoretically, as the minute scratches and other defects that are present on the surface of nearly all the materials behave as sharp pitches whose tips may be as narrow as the spacing between atoms in the materials. www.indiandentalacademy.com
  64. 64. A phenomenon known as stress concentration at the tips of these minute scratches/ flames causes the localized stress to increase to the theoretical strength of the material at a relatively low average stress throughout the structure. When the theoretical it of the material is exceeded at the tip the bonds at the notch tip break and initiate the crack formation. www.indiandentalacademy.com
  65. 65. As the crack propagates through the material the stress concentration is maintained at the crack tip until the crack moves completely through the material/ meets another. Crack a pore or a crystalline particle. Thus phenomenon of stress cone explains how materials can fail at stresses for lower than the theoretical strength. www.indiandentalacademy.com
  66. 66. Static fatigue: Exposure to water reduces the strength the porcelain causing delayed failure. Delayed failure in glasses had been attributed to a stress enhanced chemical reaction between glass and water this is likely to occur primarily at the tips of the surface cracks. www.indiandentalacademy.com
  67. 67. Water reacts with glass destroying the Si - o network and hydroxyl ions attach the siloxane bonds of the network. OH+ R—Si-O-Si-R R—SioH + R-Sio The silonate groups formed are strongly basic and can be hydrolyzed by water to form silonol groups and hydroxyl ions. R- Sio+H2O R-SioH +OH Thus in the presence of water the amount of energy required to rupture the silicone oxygen bond is diminished by about 20 times. Thus providing a surface coating for the flames reduces this. www.indiandentalacademy.com
  68. 68. METHODS OF STRENGTHENING PORCELAIN The principal deficiencies faced by ceramics are - brittleness, low fracture toughness and low tensile strength. Methods used to overcome the deficiencies fall into 2 general categories: 1. Method of strengthening brittle materials. 2. Method of designing components to minimize the stress concentrations and tensile stresses. www.indiandentalacademy.com
  69. 69. Method of strengthening materials: In the oral environment tensile stresses are usually created by bending forces, and the maximum tensile stresses occur at the surface of the restoration. It is for this reason removal of the surface flaws can result in the increased strength of the material. Smoothing and reducing flaws is one o the reason for glazing of dental porcelain. Now strengthening of the brittle materials can be done in a 2 ways. www.indiandentalacademy.com
  70. 70. 1.Development of residual compressive stresses within the surface of the material. 2. Interruption of crack propagation through the material. Development of residual compressive stresses within the surface of the material: One widely used method of strengthening ceramics is the introduction of residual compressive stresses. www.indiandentalacademy.com
  71. 71. Strength is gained by virtue of the fact that the residual stresses developed must first be negated by the developing tensile stresses before a net tensile stress develops in the material. THREE of the methods used in achieving this objective are: www.indiandentalacademy.com
  72. 72. a. ion exchange mechanism: This technique is called as chemical tempering and is the most sophisticated and effective way of introducing residual compressive stresses. In this procedure a sodium containing glass is placed in a bath of molten potassium nitrate, potassium ions in the bath exchange places with some of the sodium ions in the surface of the glass particle. The potassium ion is about 35% larger than the sodium ion. www.indiandentalacademy.com
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  74. 74. The squeezing of the potassium ion into place formerly occupied by sodium ion creates large residual compressive stresses in the surface of the glass. These residual stresses produce a strengthening effect. This process is best used on the internal surface of the crown, veneer/inlay as the surface is protected from grinding and exposure to acids. www.indiandentalacademy.com
  75. 75. The technique is as follows: Characterize the finished crown and adjust the occlusion. Place the crown into a mould of analytically pure potassium nitrate powder. Hold in a small porcelain crucible/ stainless steel container. The internal parts as the crown should be packed with the powder to ensure that it sinks in to the melting salt and does not float on the surface. www.indiandentalacademy.com
  76. 76. Place the container in a cool furnace and raise the temperature slowly to 500°C Hold the temperature at 500 C for 6 hours. Remove the crown from the solution and allow it to drain in the furnace www.indiandentalacademy.com
  77. 77. Remove the crown from the furnace and cool to room temperature. *Further more it was observed that grinding this crown by only 100 μm of the external surface reduces the strength of the materials. www.indiandentalacademy.com
  78. 78. Furthermore contact with acidulated phosphate fluoride for over 3 hours removes most of the ion exchange layer and not all ceramics are amenable for ion exchange especially those highly enriched with potash feldspar. www.indiandentalacademy.com
  79. 79. b. Thermal tempering: This is the most common method of strengthening glass. This creates residual surface compressive stresses by rapidly cooling (quenching) the surface of the object while it is hot and in the softened state. This rapid cooling produces a skin of rigid glass surrounding a soft molten core. As the molten core solidifies, it tends to shrink, but the outer skin remains rigid. www.indiandentalacademy.com
  80. 80. The pull of the solidifying molten core as it shrinks, creates residual tensile stresses in the core and residual compressive stresses within the outer surface. For dental applications it is more effective to quench the glass phase ceramics in silicone oil. Or other special liquids than using air as it may not uniformly cool the surface. www.indiandentalacademy.com
  81. 81. While doing porcelain fused to metal restorations the metal should be selected such that it contracts slightly more (higher coefficient of thermal contraction) than porcelain on cooling from the firing temperature to room temperature. This mismatch leaves the porcelain in residual compression. www.indiandentalacademy.com
  82. 82. Disruption of crack propagation This can be categorized into 3 types: 1. Crack tip interactions 2. Crack tip shielding 3. Crack bridging www.indiandentalacademy.com
  83. 83. Crack tip interactions: These occur when obstacles in the microstructure act to improve crack motion. These obstacles are generally second phase particles and act to deflect the crack out of the crack plane. It has been theorized that the reorientation of the crack plane leads to the reduction of the force being exerted of the crack in the area of deflection. www.indiandentalacademy.com
  84. 84. When the crack is deflected out of plane the crack is no longer subjected to pure tensile stresses and will involve some shear displacement; thus increasing the difficulty of crack propagation. www.indiandentalacademy.com
  85. 85. Crack tip shielding: This results when events are triggered by high stresses in the crack tip region that acts to reduce these high stresses. a. Transformation toughening b. Microcrack toughening are the 2 mechanisms that lead to crack tip shielding. This is most often associated with the presence of zirconia. Under unrestrained conditions zirconia undergoes a high to low temperature phase transformation which involves a 3% to 5°/a volume increase. www.indiandentalacademy.com
  86. 86. In toughened ceramic the high temperature phase of zirconia is constrained at room temperature. Applied tensile stress work to advance the crack plane. In the area directly behind the crack tip, the matrix constraints of zirconia are released, allowing the low temperature transformation to take place, the transformed phase occupies a greater volume in the bulk material resulting in compressive forces that tends to counteract / shield any advancing crack tip stresses. www.indiandentalacademy.com
  87. 87. Microcrack toughening: It has been theorized that the high coefficient of thermal contraction and volume reduction associated with the high to low temperature phase transformation of the leucite crystals create a condition which causes the leucite crystals to contract significantly more than the glass matrix. www.indiandentalacademy.com
  88. 88. Compressive forces are created in the glass matrix surrounding the particles leading to microcracking in the leucite phase. The residual compressive stresses in the glass phase around to particles can act to counter tensile stresses, which drive the crack forward. www.indiandentalacademy.com
  89. 89. Crack tip bridging: This it the third strengthening mechanism that has been proposed. It occurs when a second phase acts as a ligament to make it more difficult for the crack faces to open. This is better understood by bonded fiber composites. www.indiandentalacademy.com
  90. 90. The fibers act as ligaments which make it more difficult to open the crack at an applied stress. Methods of designing components to minimize stress concentrations and tensile stresses The design should avoid exposure of ceramics to high tensile stresses. It should also avoid stress concentration at sharp angles or marked changes in thickness. www.indiandentalacademy.com
  91. 91. Minimizing tensile stresses: When porcelain is fired onto a rigid material the shape of the metal will influence the stresses set up in the porcelain. If it is a full coverage crown the metal being of higher thermal expansion will contract faster than the porcelain as a result the metal is placed in tension and the porcelain in compression. www.indiandentalacademy.com
  92. 92. For partial metal coverage the junction between the metal coverage the junction between the metal and porcelain is therefore a potential site for high stress as the area with only metal will have no balancing compressive forces. www.indiandentalacademy.com
  93. 93. Reducing stress raisers; Stress raisers are discontinuities in ceramic structures in brittle materials that cause stress concentration. The design of ceramic dental restoration should also avoid stress raisers. Abrupt changes in shape/ thickness in the ceramic contour can act as stress raisers and make the restoration more prone to failure. www.indiandentalacademy.com
  94. 94. Notches caused in the porcelain due to the folds of the underlying platinum foil substrate. Sharp line angle in the preparation, large changes in the thickness of porcelain are factors creating areas of stress cone. Usually contact points should be avoided and contact areas should be preferred to avoid localized stress areas. www.indiandentalacademy.com
  95. 95. TECHNIQUE INVOLVED IN FABRICATING PORCELAIN FUSED TO METAL There are 2 basic methods of fabricating porcelain fused to metal. 1.Involves the swaging of a platinum matrix on a model of the tooth and building the porcelain. 2. Supporting the porcelain to metal foundation. www.indiandentalacademy.com
  96. 96. Platinum foil technique: This technique involves fabrication on either a single platinum foil or a double platinum foil. Fabrication on single platinum foil: A pure platinum foil is swaged directly to the model then the porcelain is built up. Later after the completion as the firing cycles the platinum is peeled off. The fit of the crown is secured leaving enough space for the cement. www.indiandentalacademy.com
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  107. 107. Fabrication using a double foil matrix technique: Here a second layer of platinum foil is swaged on the first and cut back by at least 0.5 mm from the gingival shoulder. The second layer is sand basted and cleaned with caustic soda and citric acid to improve impurities this is followed by electroplating, oxidization and finally build up of the porcelain. Later after the procedure is accomplished the inner layer is removed allowing space for the placement of the cement. www.indiandentalacademy.com
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  109. 109. Swaged gold alloy foil capping: A laminated gold foil supplied in fluted shape is also used as an alternative to the cast metal coping. The foil is swaged onto the die and flame sintered to form a coping. An interfacial alloy powder is applied and fired, then the coping is veneered with porcelain. www.indiandentalacademy.com
  110. 110. Supporting the porcelain of a metal foundation The various alloys that can be used are High noble. - Gold platinum palladium - Gold palladium silver - Gold palladium Have noble metal content greater than 60% with at least 40% gold. www.indiandentalacademy.com
  111. 111. Noble: - Palladium silver -High palladium They have less than 25% noble metal content www.indiandentalacademy.com
  112. 112. Predominantly base metals: - Nickel chromium - Nickel chromium - Cobalt beryllium www.indiandentalacademy.com
  113. 113. BONDING MECHANISMS Four mechanism have been described to explain the bond between the ceramic veneer and the metal substructure. 1. Mechanical entrapment 2. Compressive forces 3. Van der waals forces 4. Chemical bonding www.indiandentalacademy.com
  114. 114. Mechanical entrapment: This creates attachment by interlocking the ceramic into the microabrasions on the surface of the metal coping which are created by finishing the metal with non contaminating stones / discs and are abrasives. Air abrasion appears to enhance the wettability, provide mechanical interlocking The use of a bonding agent having platinum spheres 3-6 μm in diameter can also increase the bond significantly. www.indiandentalacademy.com
  115. 115. Compressive forces: These are developed by a properly designed coping and a slightly higher coefficient of thermal expansion than the porcelain veneered over it. This slight difference will cause the porcelain to draw towards the metal coping when the restoration cools after firing. www.indiandentalacademy.com
  116. 116. Vander waals forces It is an affinity based on a mutual attraction of charged molecules. They are minor force for bonding. Chemical bonding It is indicated by the formation of an oxide layer on the metal. The trace elements like tin, indium, gallium/iron form oxides and bond to similar oxides in the opaque layer of the porcelain. www.indiandentalacademy.com
  117. 117. Bonding of porcelain to metal using electrodeposition: A layer of pure gold is deposited onto the cast metal, followed by a short flashing deposition of tin. This method has been successfully used for metals and alloys such as cobalt, chromium, stainless steel, palladium silver, high and low gold content alloys and titanium. www.indiandentalacademy.com
  118. 118. The advantages of this methods are: 1. Bonding is improved because of improved wetting the metal by the porcelain and reduced porosity at the porcelain metal interface 2. The electrodeposited layer acts as barrier between the metal casting and porcelain to inhibit ion penetration by the metal within normal limits of porcelain maturation www.indiandentalacademy.com
  119. 119. 3. The gold color of the oxide film improves the vitality and esthetics of porcelain, when compared to the normal dark oxides which require thick opaque layers of porcelain to mark it. 4. The deposited layer acts as a buffer zone to absorb stresses. www.indiandentalacademy.com
  120. 120. Classification of bond failures in metal ceramics: www.indiandentalacademy.com
  121. 121. Metal porcelain: Fracture leaves a clean surface of metal. Seen when metal surface is devoid of oxides. May also be due to contaminated or porous metal surfaces. Metal oxide porcelain: Porcelain fractures at metal oxide surface, leaving oxide firmly attached to the metal seen often in base metal alloys. www.indiandentalacademy.com
  122. 122. Metal-metal oxide: Metal oxide breaks away from the metal and is left attached to the porcelain seen commonly in base metal alloy systems due to overproduction of Ch /Ni oxides Metal oxide - metal oxide: Fracture through the metal oxides results from over production of oxide. www.indiandentalacademy.com
  123. 123. Alloy surface treatment: Once the coping in made proper finishing with aluminium oxide strips is done to remove any surface irregularity and small particles as investment that may have been embedded in the surface of the casting. www.indiandentalacademy.com
  124. 124. Heat treatment: The coping is placed in a furnace at relatively low temperature and is then raised slowly to about 1000°C in vacuum and slowly air cooled in normal atmosphere. This process of degassing allows any contaminants/ gas inclusion to burn off. At the same time base metal atoms will diffuse to the surface of the metal and form on oxide film, tin. www.indiandentalacademy.com
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  126. 126.  ThicknessThickness::  Cleaning :Cleaning : www.indiandentalacademy.com
  127. 127. OxidizingOxidizing Controlled oxide layerControlled oxide layer should be created .should be created . OPAQUE LAYEROPAQUE LAYER APPLICATION.APPLICATION. www.indiandentalacademy.com
  128. 128. Methods of condensation: The Porcelain is mixed and applied. Vibration: Mild vibrations are used to densely pack the wet powder upon the underlying matrix. The excess water comes to the surface and is blotted with a tissue paper. www.indiandentalacademy.com
  129. 129. Spatulation: A small spatula is used, to apply and smoothen the wet porcelain. This action brings excess water to the surface. Brush technique: Dry powder is placed by a brush. Water is drawn towards the dry powder and the wet particles are pulled together. Ultrasonic: Mild vibrations are transmitted electrically. www.indiandentalacademy.com
  130. 130. METHODS OF BUILDING AND CONDENSING PORCELAIN The porcelain is usually built to shape using a liquid binder to hold the particles together. This process of packing the particles and removing the liquid is known as condensation. The main objective in building porcelain powder is to achieve maximum packing density of the powder i.e. minimum amount of air space is left in the green or inferred porcelain after driving off the liquid binder by heating. www.indiandentalacademy.com
  131. 131. Types of binders: Distilled water: Is the most popular binder used in dentin and enamel porcelain. Propylene glycol: Used in alumina core build up. Alcohol or formaldehyde based liquid for opaque / core build up. www.indiandentalacademy.com
  132. 132. Building porcelain: 1 The powder is mixed on a glass slab. 2. The mix should not be overstored to avoid the incorporation of large air bubbles. 3. High room temperature and dry atmosphere is to be avoided as the powder can dry out rapidly due to which all spaces are created in the powder bed. Crowns which are built from such a build up will inevitably be subjected to the entrapment of large air bubbles and areas which are opaque may appear. www.indiandentalacademy.com
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  136. 136. Firing dental porcelain: After the condensation and building of a crown it is fired to high density and correct form. Initially the infected/ green porcelains placed on a sager and introduced into either a drying chamber/ the entrance of a furnace muffle. The liquid binder is driven off and the porcelain become brittle and chalky. www.indiandentalacademy.com
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  139. 139. At this stage the green porcelain is introduced into the hot zone of the furnace and the firing starts, the glass particles soften at their contact areas and fuse together. This is often referred to as sintering. Before firing the temperature is raised gradually to the manufacturers recommended temperature. www.indiandentalacademy.com
  140. 140. This allows the air/gas bubbles to escape via the grain boundaries. Sealing the surface by quick firing arrests the process and can cause bloating / blustering. The powder will shrink and become denser. In air fired porcelain a pint is reached where flow of glass grains around the air spaces trips the remaining air in the porcelain and on cooling spheroid bubbles are left in the porcelain. However, then porcelain is fired in vacuum, the air/atmosphere is removed from the interstitial spaces before sealing of the surface occurs. www.indiandentalacademy.com
  141. 141. Do not prolong vacuum firing as by then the surface skin is sealed and further application of vacuum can cause surface blistering since residual air bubbles will try to rise to the surface through the molten porcelain. www.indiandentalacademy.com
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  144. 144. Classification of the stages in Maturity: Low Bisque: The surface of the porcelain is very porous and will easily absorb a water soluble die. At this stage the grains of porcelain will have started to soften. Shrinkage will be minimal and the fired body is extremely weak and friable. Lack translucency and glaze. www.indiandentalacademy.com
  145. 145. Medium bisque: The surface will still be slightly porous but the flow of the glass grains will have increased. A definite shrinkage will have taken place. Lacks translucency and high glaze. High bisque: The surface of the porcelain would be completely sealed and presents a much smoother surface with a slight shine. shrinkage is complete. Appears glazed. www.indiandentalacademy.com
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  147. 147. Cooling Must be carried out slowly and uniformly. If shrinkage is not uniform it causes cracking and loss of strength. Glazing Porcelains are glazed to give a smooth and glossy surface, enhance, esthetics and promote hygiene. www.indiandentalacademy.com
  148. 148. The glazing should be done only on a slightly roughened surface and never should be applied on glazed surfaces. 1. Overglaze 2. Self glaze www.indiandentalacademy.com
  149. 149. Over glaze: These are ceramic powders containing more amount of glass modifiers thus lowering fusion temperature. It may be applied to porcelain and then fired. Self glaze: All the constituents on the surface are melted to form a molten mass about 25 μm thick. Thus the porcelain is said to be self glazed. www.indiandentalacademy.com
  150. 150. Add on porcelains The add on porcelains are made from similar materials to glaze porcelain except for the addition of opacifiers and coloring pigments. The add on porcelain is made from the same grit as used to manufacture regular porcelain. These are sparingly used for simplest corrections like correcting of tooth contour / contact points. www.indiandentalacademy.com
  151. 151. Repair of fracture ceramic restoration Roughen the fracture ceramic surface using an intraoral sand blaster generally using 30-50 μm aluminium grit. Silane is applied. Dentine bonding agent containing 4 META applied to the porcelain surface. The defect is restored with composite restorative material. www.indiandentalacademy.com
  152. 152. Aluminous porcelain: There were developed by Mc Lean in 1965. Its composition is similar to that of conventional porcelain except for the increased alumina content (40-50%). The dispersed alumina crystal strengthens by interruption of crack propagation. The crack cannot penetrate the alumina crystals as easily as it can penetrate through the glass. www.indiandentalacademy.com
  153. 153. These are used to construct the core layer for PJC. These are considered to provide crowns more esthetics than metal ceramic crowns. Their strength is almost twice that of conventional porcelains and is sufficient for use on anterior teeth. However, for posterior teeth it is inadequate. www.indiandentalacademy.com
  154. 154. These are moreover less expensive than metal ceramic crowns. But the disadvantage of this material is the addition of alumina which makes it opaque. Aluminous porcelain shrink during the baking procedure, the fit of the finished aluminous crowns is generally poorer than that of ceramometal crowns. www.indiandentalacademy.com
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  156. 156. Since the introduction of the first successful porcelain fused to metal in the early 1960’s there has been an increasing demand for ceramic materials. This popularity is a result of the range of shades that can help achieve life like results. However, because of their relatively low tensile strength and brittleness it has been fused to a metal substrate. www.indiandentalacademy.com
  157. 157. However, this meta substrate can affect the esthetics of porcelain by decreasing the light transmission and by creating metal ion discoloration, in addition some patients are allergic / sensitive to certain metals. All these drawbacks led to the development of the new call ceramic systems. www.indiandentalacademy.com
  158. 158. The evolution of ceramic materials has been a battle for the ideal strength, aesthetic combination. The first all ceramic crowns introduced by Land in 1903 were relatively weak materials with limited clinical use. In 1965 McLean and Hughes formulated aluminous porcelain compositions. www.indiandentalacademy.com
  159. 159. These materials are composed of feldspathic porcelain to which approximately 50% aluminium oxide is added to increase the strength and baking temperature.40 -80 % alumina crystals and rest is formed as feldspar, quartz and Kaolin. The fabrication is similar to feldspathic porcelain except that the sintering should be slow to allow the porosities to escape. The porcelain should not reach the maturing temperature in less than 5 minutes. www.indiandentalacademy.com
  160. 160. Classification of all ceramic systems: i. Conventional powder and slurry ceramics ii. Castable ceramics iii. Machinable ceramics iv. Infiltrated ceramics www.indiandentalacademy.com
  161. 161. ALUMINOUS CORE CERAMICSALUMINOUS CORE CERAMICS  Mclean and Hughes 1965.Mclean and Hughes 1965.  Alumina content 40-55%.Alumina content 40-55%.  Aluminous oxide crystals dispersed in a glassy matrixAluminous oxide crystals dispersed in a glassy matrix  Method consisting of bonding aluminous porcelain toMethod consisting of bonding aluminous porcelain to platinum foil copingplatinum foil coping  Foil provides inner skin –decreases subsurface porosity andFoil provides inner skin –decreases subsurface porosity and formation of micro cracks and increases strengthformation of micro cracks and increases strength www.indiandentalacademy.comwww.indiandentalacademy.com
  162. 162. Strength twice that of conventional porcelain sufficient to use in anterior teeth but is considered inadequate to use in posterior teeth. flexural strength-100 MPa. particle size 10-25 microns. Example- vitadur N Used as core. www.indiandentalacademy.comwww.indiandentalacademy.com
  163. 163. CASTABLE GLASS CERAMICSCASTABLE GLASS CERAMICS  DICORDICOR: By Corning glass works and marketed by: By Corning glass works and marketed by DentsplyDentsply  Lost wax technique.Lost wax technique.  After the core is recovered it is then covered byAfter the core is recovered it is then covered by protective embedment material and subjected to heatprotective embedment material and subjected to heat treatment that causes the microscopic plate liketreatment that causes the microscopic plate like crystals to grow --- CERAMMING.crystals to grow --- CERAMMING. www.indiandentalacademy.comwww.indiandentalacademy.com
  164. 164.  Good esthetics --- chameleon effectGood esthetics --- chameleon effect  55% tetrasilicic fluoromica crystals.55% tetrasilicic fluoromica crystals. www.indiandentalacademy.comwww.indiandentalacademy.com
  165. 165. Ceramming increases strength, toughness, increasesCeramming increases strength, toughness, increases resistance to abrasion, chemical durability and decreasesresistance to abrasion, chemical durability and decreases translucency.translucency. Particle size 5-7 microns, volume 50% www.indiandentalacademy.comwww.indiandentalacademy.com
  166. 166.  DICOR MGCDICOR MGC  70% TETRASILICIC FLUROMICA CRYSTAL.70% TETRASILICIC FLUROMICA CRYSTAL.  Particle size 1-5 microns, volume 65 %.Particle size 1-5 microns, volume 65 %.  Provided as CAD/CAM blanksProvided as CAD/CAM blanks  No longer soldNo longer sold  DisadvantagesDisadvantages Limited use in low stress bearing areasLimited use in low stress bearing areas Unable to color internallyUnable to color internally www.indiandentalacademy.comwww.indiandentalacademy.com
  167. 167.  Dicor plus : pigmented feldspathic porcelainDicor plus : pigmented feldspathic porcelain veneer.veneer.  Willis glass : veneer of aluminous porcelain.Willis glass : veneer of aluminous porcelain. www.indiandentalacademy.comwww.indiandentalacademy.com
  168. 168. PRESSABLE GLASS CERAMICPRESSABLE GLASS CERAMIC  MacCulloch in 1968MacCulloch in 1968  Type of Feldspathic porcelainType of Feldspathic porcelain  IPS Empress 1--- Leucite 35%IPS Empress 1--- Leucite 35% adv : translucent, increased flexural strength,adv : translucent, increased flexural strength, Excellent fit and estheticsExcellent fit and esthetics IPS Empress 2 ---- Lithia disilicate 70%IPS Empress 2 ---- Lithia disilicate 70% Scattering similar to tooth enamelScattering similar to tooth enamel www.indiandentalacademy.comwww.indiandentalacademy.com
  169. 169. SLIP CAST CERAMICSSLIP CAST CERAMICS  SLURRY OF MATERIAL IS SLIP CAST ON THE DIE ANDSLURRY OF MATERIAL IS SLIP CAST ON THE DIE AND HEATED IN THE FURNACE TO PRODUCE A PARTIALLYHEATED IN THE FURNACE TO PRODUCE A PARTIALLY SINTERED COPING.SINTERED COPING.  THIS COPING IS INFILTRATED WITH GLAS AT 1100THIS COPING IS INFILTRATED WITH GLAS AT 1100 FOR 4 HRS TO STRENGTHEN COREFOR 4 HRS TO STRENGTHEN CORE  EX: ICS, ICA, ICZEX: ICS, ICA, ICZ www.indiandentalacademy.comwww.indiandentalacademy.com
  170. 170. ceramicceramic CeramicCeramic typetype CeramicCeramic veneerveneer IndicationsIndications FlexuralFlexural strengthstrength (Mpa)(Mpa) ICSICS Mgo-Mgo- alal22oo33 aluminousaluminous porcelainporcelain Anterior crownAnterior crown 350350 ICAICA AlAl22oo33 aluminousaluminous porcelainporcelain Anterior crownAnterior crown and posteriorand posterior crown andcrown and anterior FPDanterior FPD 500500 ICZICZ AlAl22oo33-- zrozro aluminousaluminous porcelainporcelain Posterior crownPosterior crown and posterior FPDand posterior FPD 700700 www.indiandentalacademy.comwww.indiandentalacademy.com
  171. 171. Fabrication stepsFabrication steps www.indiandentalacademy.comwww.indiandentalacademy.com
  172. 172. www.indiandentalacademy.comwww.indiandentalacademy.com
  173. 173. www.indiandentalacademy.comwww.indiandentalacademy.com
  174. 174. www.indiandentalacademy.comwww.indiandentalacademy.com
  175. 175. www.indiandentalacademy.com
  176. 176. www.indiandentalacademy.com
  177. 177. REFERENCES 1. Science of dental materials- K J Anusavice 2. Restorative dental materials - R G Craig 3. Dental biomaterials- E C Coombe 4. Applied dental Materials - John F McCabe 5. Introduction to Dental Materials- Richard Van Noort www.indiandentalacademy.com
  178. 178. Evolution of dental ceramics in twentieth century-J W McLean, J Prosthet Dent 2001,85(1),61-66. Future ceramic systems -J F Roulet and R Landa, Operative Dentistry 2001,6,211- 218. Recent advances in ceramics for dentistry-I L Denry, Crit Rev Oral Biol Med 1996,7(2),134-143. Dental Ceramics an update-V Piddock and J E Qualtrough, J Dent 1990,18,227-235. Recent developments in restorative dental ceramics-K J Anusavice,JADA,124,1993 A review of All-Ceramic Restorations- M A Rosenblum and A Schulman,JADA,128,1997297-307. www.indiandentalacademy.com
  179. 179. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.comwww.indiandentalacademy.com

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