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All Ceramics Dr. Nithin Mathew
1
ALL CERAMICS(Material Aspect)
Dr. Nithin Mathew
All Ceramics Dr. Nithin Mathew
CONTENTS
3
Introduction
History
Classification
Composition
Advantages & disadvantages
Manufacture
Fabrication
Methods of strengthening ceramics
All Ceramic Systems
Selection of ceramics
Conclusion
References
All Ceramics Dr. Nithin Mathew
INTRODUCTION
Ceramic - First material to be artificially made by humans.
Ceramic is derived from the Greek word keramos, which means potter's clay.
Earliest techniques consisted of shaping the item in clay/soil and then baking it to fuse the
particles together, which resulted in coarse and porous products.
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All Ceramics Dr. Nithin Mathew
The term CERAMIC refers to any product made essentially from a non metallic inorganic
material processed by firing at a high temperature to achieve desirable properties.
DENTAL CERAMIC (Anusavice)
A specially formulated ceramic material that exhibits adequate strength, durability and
color that is used intraorally to restore anatomic form and function, and/or esthetics.
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All Ceramics Dr. Nithin Mathew
CERAMICS
Compounds of one or more metals with a non metallic element (usually silicon,
boron, oxygen) that may be used as a single structural component or as one of the
several layers that are used in the fabrication of a ceramic based prosthesis.
(Glossary of Prosthodontic Terms)
PORCELAIN
A ceramic material formed of infusible elements joined by lower fusing materials.
(Glossary of Prosthodontic Terms)
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All Ceramics Dr. Nithin Mathew
Terminologies
COPY-MILLING
A process of machining a structure using a device that traces the surface of master
metal, ceramic, or polymer pattern and transfers the traced spatial positions to a
cutting station where blank is cut or ground in a manner similar to key-cutting
procedure.
SINTERING
The process of heating closely packed particles to achieve interparticle bonding and
sufficient diffusion to decrease the surface area or increase the density of the
structure.7
All Ceramics Dr. Nithin Mathew
VITRIFICATION :
The development of a liquid phase by reaction or melting, which on cooling provides
the glassy phase, resulting in a vitreous structure.
When the glass begins to crystallize , the process is called DE-VITRIFICATION.
GREEN STATE :
A term referred to as pressed condition before sintering.
SPINEL :
A crystalline mineral composed of mineral oxides such as magnesium oxide or
aluminium oxide.
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All Ceramics Dr. Nithin Mathew
SLIP CASTING :
A process used to form green ceramic shapes by applying a slurry of ceramic
particles and water or special liquid to a porous substrate, thereby allowing capillary
action to remove water and densify the mass of deposited particles.
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All Ceramics Dr. Nithin Mathew 10
ADA SPECIFICATION
Dental ceramic : 69
Dental porcelain teeth : 45
Metal ceramic system : 38
ISO SPECIFICATION
Dental ceramic : 6872
Dental porcelain teeth : 22112
Metal ceramic system : 9693
All Ceramics Dr. Nithin Mathew
HISTORY
1728 : Proposed the use of porcelain in dentistry Pierre Fauchard
1774 : Made first porcelain denture Alexis Duchateau
1789 : First porcelain tooth material patented - de Chemant & Duchateau
1808 : Terrometallic porcelain tooth Fonzi
1817 : Porcelain teeth introduced in the US Planteau
1825 : Commercial production of porcelain teeth (SS White Company) Samuel Stockton
1837 : Introduced improved version of porcelain- Ash
1887 : Introduced porcelain jacket crown using platinum foil matrix technique - CH. Land
1903 : First ceramic crowns introduced to dentistry Charles Land
1957 : Introduced Vacuum firing - Vines & Sommelman
1962 : Formulation of feldspathic porcelain Weinstein & Weinstein11
All Ceramics Dr. Nithin Mathew
1963 : First commercial feldspathic porcelain developed Vita Zahnfabrik
1965 : Aluminous core ceramic Mclean and Hughes
1968 : Use of glass ceramics MacCulloh
1983 : Bonding composite resin to acid etched porcelain Simonsen & Calamia
1983-84 : First castable ceramic Dicor Grossman & Adair
1985 : First CAD/CAM was publicly milled and installed in the mouth Morman & Brandestini
1987 : CEREC 1 was introduced
1989 : First slip cast alumina ceramic- Inceram alumina- Sadoun
1991 : Pressable glass ceramics- Wohlwent
1994 : CEREC 2 was introduced
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All Ceramics Dr. Nithin Mathew
1997 : Sirona CROWN 1.0 program for producing full-ceramic posterior crowns was introduced
2000 : CEREC 3 was introduced
2008 : Sirona released the MCXL milling unit which can produce a crown in 4 mins
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All Ceramics Dr. Nithin Mathew
CLASSIFICATION
Firing temperature
Use / Indications
Fabrication techniques
Crystalline phases
Microstructure
Translucency
According to system
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All Ceramics Dr. Nithin Mathew
FIRING TEMPERATURE
High fusing : > 1300C
Medium fusing : 1101 - 1300C
Low fusing : 850 - 1100C
Ultralow fusing : < 850C
15
USE / INDICATIONS
Veneers
All ceramic crowns
Inlays and onlays
Ceramic dentures
Post & Cores
Orthodontic brackets
FPD
All Ceramics Dr. Nithin Mathew
FABRICATION TECHNIQUE
Sintered (Metal Ceramics)
Cast (Dicor)
Heat pressed (IPS Empress)
Slip cast (Inceram)
Machined (Cerec Vitablocs)
Partial sintering and glass infiltration
CAD CAM & copy milling
16
CRYSTALLINE PHASE
Alumina based (Optec HSP)
Feldspar based (Conventional Ceramics)
Leucite based (IPS Empress)
Spinel based (Inceram Spinel)
All Ceramics Dr. Nithin Mathew
TRANSLUCENCY
Opaque
Translucent
Transparent
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MICROSTRUCTURE
Glass
Crystalline
Crystal containing glass
All Ceramics Dr. Nithin Mathew
COMPOSITION
Pure alumina
Pure Zirconia
Silica glass
Spinelle
Leucite based glass ceramic
Lithia based glass ceramic
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APPLICATION
Core porcelain
Body porcelain
Enamel porcelain
All Ceramics Dr. Nithin Mathew
According To Systems
Metal ceramic systems Cast metal systems and non cast systems
All ceramic systems Conventional powder slurry ceramic
i. Alumina reinforced porcelain
ii. Magnesia reinforced porcelain
iii. Leucite reinforced
iv. Zirconia-whisker fiber reinforced
v. Low fusing ceramics
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All Ceramics Dr. Nithin Mathew
Castable Ceramicsi. Flouormicasii. Other Glass Ceramics
Machinable Ceramicsi. Analogus Systems
a. Copymillinga. Mechanicalb. Automated
b. Erosive Techniques a. Sono - erosionb. Spark - erosion
ii. Digital Systems (CAD/CAM)i. Directii. Indirect
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Pressable Ceramicsi. Shrink free ceramicsii. Leucite reinforced ceramics
Infiltrated Ceramicsi. Alumina basedii. Spinel basediii. Zirconia based
All Ceramics Dr. Nithin Mathew
Primary constituent Minerals composed of potash (KO), soda(NaO) and silica (SiO) 75-85%
Feldspar
4-5% Increases the moldability of the plastic porcelain Serves as a binder Consists of AlO 2SiO 2HO (Hydrated Aluminium Silicate) Kaolin is opaque and can lower the translucency of porcelain
Kaolin
Present in concentrations of 13-14% Provide strength, firmness and improve translucency of porcelain Serves as a framework for other ingredients
Quartz
21
Composition of Dental Ceramics
All Ceramics Dr. Nithin Mathew 22
GLASS MODIFIERS
Potassium, sodium and calcium oxides
Serve as fluxes
Lower the viscosity of glass
Increase thermal expansion
OPACIFYING AGENTS
Zirconium oxide
Titanium oxide
Tin oxide
All Ceramics Dr. Nithin Mathew
PIGMENTS
To obtain various shades to mimic natural tooth colour.
Made by fusing metallic oxide with fine glass and feldspar & regrinding to a powder.
.
23
Metallic oxide Colour
Iron or nickel oxide Brown
Copper oxide Green
Titanium oxide Yellowish brown
Manganese oxide Lavender
Cobalt oxide Blue
All Ceramics Dr. Nithin Mathew
ADVANTAGES of Dental Ceramics
Highly esthetic
Biocompatibility
Electrical Resistance
Thermal Insulation
Wear resistance
Can be formed to precise shapes
Ability to be bonded to tooth structure
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All Ceramics Dr. Nithin Mathew
DISADVANTAGES
Brittleness
Fabrication : Technique sensitive
Wear of opposing natural teeth
Difficult to repair intraorally
High cost of fabrication
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All Ceramics Dr. Nithin Mathew
MANUFACTURING OF CERAMICS
Pyro-chemical reactions during manufacture of porcelain:
Ceramic raw materials are mixed together in a refractory crucible and heated to a
temperature well above their fusion temp
Series of reactions occur.
26
CaCO3
P2O5
BaCO3
SiO2
Al2O3
MgO MgF2 CaF2
All Ceramics Dr. Nithin Mathew
MANUFACTURING OF CERAMICS
After the water of crystallization is lost,
Flux reacts with the outer layers of silica, kaolin and feldspar
Feldspar fuses and intermingles with kaolin and quartz
Feldspar undergoes decomposition to form glass and leucite
The molten glass begins to dissolve the quartz and kaolin
Continuous heating results in total dissolution
Then the fused mass is quenched in water
27
CaCO3
P2O5
BaCO3
SiO2
Al2O3
MgO MgF2 CaF2
All Ceramics Dr. Nithin Mathew
Internal stresses within the glass are produced and breaks into fragments frit
The process of blending, melting and quenching the glass is called FRITTING
28
CaCO3
P2O5
BaCO3
SiO2
Al2O3
MgO MgF2 CaF2
Crucible
All Ceramics Dr. Nithin Mathew 29
Melting
CaCO3
P2O5
BaCO3
SiO2
Al2O3
MgO MgF2 CaF2
Tank with cool water
Quenching
FritSieving
MANUFACTURING OF CERAMICS
All Ceramics Dr. Nithin Mathew
Ceramics : 2 phases
Glassy Phase (Vitreous) Provides translucency Makes ceramic brittle
Crystalline Phase Added to improve the mechanical properties Newer ceramics (35-90%)
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All Ceramics Dr. Nithin Mathew
DISPENSING
Conventional dental porcelain kit supplied as a kit containing :
Fine ceramic powder in different shades of enamel, dentin, core/opaque
Special liquid or distilled water
Stains and colour modifiers
Glazes and add-on porcelain
Shade guide
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All Ceramics Dr. Nithin Mathew
FABRICATION OF CERAMIC RESTORATIONS
The fabrication of conventional porcelain restoration is by : Condensation Sintering Glazing Cooling
CONDENSATION :
Padding or packing of wet porcelain into position The movement of particles is generated by vibration, spatulation or whipping, brush
technique and spray opaquing.
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All Ceramics Dr. Nithin Mathew
CONDENSATION :
Build-up of Cervical Porcelain
Build-up of Body Porcelain
Cut-back
Build-up of Enamel Porcelain
Condensation methods:
MANUAL CONDENSATION ULTRASONICCONDENSATION
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All Ceramics Dr. Nithin Mathew
Advantages of ultrasonic condensation:
Reduces the fluid content of layered ceramics; resulting in denser and more vibrant porcelainmass.
Enhances translucency and the shade qualities of the fired ceramic.
Shrinkage can be reduced to below 5%
Time-saving as it reduces the number of compensatory firing cycles
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All Ceramics Dr. Nithin Mathew
SINTERING / FIRING :
Process of heating closely packs particles to achieve interparticle bonding and sufficient
diffusion to decrease the surface area or increase density of the structure.
Process of partial fusion of compact glass
Steps:
Pre-heating the furnace
Condensed mass placed
Green porcelain is fired
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All Ceramics Dr. Nithin Mathew
Pre-heating (Drying):
Placing the porcelain object on a tray in front of a preheated furnace at 650C for 5min for low
fusing porcelain and at 480C for 8min for high fusing porcelains till reaching the green or
leathery state.
36
Significance:
Removal of excess water allowing the porcelain object to gain its
green strength.
Preventing sudden production of steam that could result in voids
or fractures.
Ceramic particles held together in the green state after all liquid has been dried off
All Ceramics Dr. Nithin Mathew
SINTERING / FIRING :
37
FIRING TECHNIQUES
According to temperature presetting:
Temperature controlled
method
Temperature time control
method
According to the media employed for firing:
AIR FIRING
Porosity due to air inclusion
VACUUM FIRING
Reduce porosity
DIFFUSABLE GASES
Helium, hydrogen or
steam are substituted for
the ordinary furnace
All Ceramics Dr. Nithin Mathew
Stages of Maturity of Porcelain during Firing
Bisque bake
A series of stages of maturation in the firing of ceramic materials depending on the degree of
pyrochemical reaction and sintering shrinkage occurring before vitrification (glazing).
Low bisque
Medium bisque
High bisque
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All Ceramics Dr. Nithin Mathew
Low bisque
Surface of porcelain is very porous and will easily absorb water.
Medium bisque
Surface is still porous but the flow of the glass grains is increased and entrapped air
will become sphere shaped.
High bisque
Surface is completely sealed and presents a smooth texture.
Overfired porcelain become milky or cloudy in appearance Devitrification.
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All Ceramics Dr. Nithin Mathew
STAGES OF MATURITY
40
Low bisque stage Medium bisque stage High bisque stage
Characteristics Grains of porcelain start to soften and coalesce at the contact points
Flow of glass grains increase and the residual entrapped furnace air becomes sphere shaped
Firing shrinkage is complete,and has adequate strength, for any corrections by grinding prior to glazing
Particle cohesion Incomplete Considerable CompletePorosity Highly porous and absorbs
waterReduced although still porous
Slight/absent depending upon the material used
Shrinkage Minimal Majority / definite CompleteStrength Weak & friable Moderate High Surface texture Porous Matte surface Egg shell appearance
Color & translucency
Opaque Less opaque Color and translucency developed
All Ceramics Dr. Nithin Mathew
GLAZING :
Produces smooth, shiny and impervious outer layer, also effective in reducingcrack propagation.
2 ways : Add-on glazing Self glazing most preferred technique
COOLING :
Carried out slowly Rapid cooling results in cracking or fracture of glass and loss of strength. After firing, placed under a glass cover to protect it from air current and
contamination by dirt.41
All Ceramics Dr. Nithin Mathew
Porcelain Surface Treatment
Natural or Autoglaze
Porcelain has the ability to glaze itself when held at its fusing temperature in air for 1-4
mins.
Porcelain loses its ability to form a natural glaze after multiple firings
Applied Overglaze
Applied overglaze is a low fusing clear porcelain painted on to the restoration and fired at
a fusing temperature much lower than that of the dentin and enamel porcelain.
An applied overglaze is indicated in large restoration that have numerous corrections.46
All Ceramics Dr. Nithin Mathew
Instrumentation for Finishing and Polishing Ceramic Restorations
47
Sequence Instruments
1 Medium to fine grit diamond instrument
2 30 fluted carbide burs
3 Rubber, abrasive impregnated porcelain polishing points
4 Diamond polishing paste
All Ceramics Dr. Nithin Mathew
Methods of Strengthening Ceramics
Minimize the effect of stress raisers
Develop residual compressive stresses
Minimize the number of firing cycles
Ion exchange
Thermal tempering
Dispersion strengthening
Transformation toughening
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All Ceramics Dr. Nithin Mathew
1. Minimize the effect of stress raisers
Stress raisers are discontinuities in ceramic and metal ceramic structure that causes stress
concentration.
Restoration should be designed in such a way that it avoids exposure of ceramic to high tensile
stresses.
Use of maximum thickness of ceramic on the occlusal surface.
Abrupt changes in the shape or thickness in ceramic contour should be avoided.
Sharp line angles in the preparation can cause stress concentration.
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All Ceramics Dr. Nithin Mathew
2. Develop residual compressive stresses
The coefficient of thermal contraction of metal should be slightly higher than that of porcelain.
Metal contracts slightly more than the porcelain on cooling from firing temperature to room
temperature
Leave porcelain in residual compression and provides additional strength for the prostheses.
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All Ceramics Dr. Nithin Mathew
3. Minimize the number of firing cycles
Leucite is a high expansion crystal phase which affects the thermal contraction coefficient of
porcelain.
Multiple firings increases concentration of crystalline leucite.
Increasing the no. of firing cycles can increase the LCTE of veneering porcelain. This leads to
stresses on cooling.
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All Ceramics Dr. Nithin Mathew
4. Ion exchange/ Chemical tempering
Effective method of inducing residual compressive stresses.
Sodium containing glass article is placed in a bath of molten potassium nitrate
Exchange of ions take place
Since potassium ion is 35% larger than sodium ion, squeezing of the potassium ion createsvery large residual compressive stresses.
Potassium rich slurry, applied to ceramic surface and heated
to 450C for 30 mins.
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All Ceramics Dr. Nithin Mathew
5. Thermal Tempering
Creates residual compressive stresses by rapidly cooling the surface of the object while it is in
the molten state.
Rapid cooling produces a skin of rigid glass surrounding a molten core.
The solidifying molten core as it shrinks, creates residual compressive stress within the outer
surface.
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All Ceramics Dr. Nithin Mathew
6. Dispersion Strengthening
Process of strengthening ceramics by reinforcing them with a dispersed phase of a different
material.
Most dental ceramics are reinforced by dispersion of crystalline substances.
Ex. Alumina in aluminous porcelain, spinel in In Ceram.
When crystalline material such as alumina (AlO) is added to a glass, the glass is
strengthened and crack propagation does not take place easily.
Resulted in development of aluminous porcelain for porcelain jacket crowns.
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All Ceramics Dr. Nithin Mathew
7. Transformation Toughening
This method also relies on dispersion of a crystalline material within the ceramic.
Strengthening occurs due to a change in the crystal structure under stress which prevents
crack propagation.
Dental ceramics based primarily on zirconia crystals when heated to a temperature between
1470C and 2010C undergo change in the crystal structure from tetragonal to a monoclinic
phase at approx. 1150C
The toughening mechanism results from the controlled transformation of metastable
tetragonal phase to the stable monoclinic phase.55
All Ceramics Dr. Nithin Mathew
ALL CERAMIC SYSTEMS
Classified according to the method of fabrication:
Conventional (powder slurry) ceramics
Infiltrated / Slip Cast Ceramics
Castable Ceramics
Pressable Ceramics
Machinable Ceramics
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All Ceramics Dr. Nithin Mathew
CONVENTIONAL CERAMICS(POWDER SLURRY)
All Ceramics Dr. Nithin Mathew
Supplied as powders in different shades & translucencies.
Mixed with water to form slurry
Slurry build up in layers on a refractory die
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All Ceramics Dr. Nithin Mathew
ALUMINOUS CORE PORCELAIN
Mc Lean and Hughes developed a PJC with an alumina reinforced
Significant improvement in fracture resistance
Consisted of a glass matrix containing between 40-50 wt% of Al2O3.
Large sintering shrinkage (15-20%)
Inadequate translucency
Principle indication: maxillary anterior crown restoration
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All Ceramics Dr. Nithin Mathew
DisadvantagesAdvantages
Improved Fracture Resistance
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Low CTE : 8 x 10-6/0C.
Large sintering shrinkage (15-20%)
Improvement in strength is insufficient to
bear high stresses
All Ceramics Dr. Nithin Mathew
MAGNESIA REINFORCED PORCELAIN
OBrien in 1984 High expansion ceramics Core material Crystalline magnesia (40-60%) Forsterite.
Magnesia crystals strengthen glass matrix by both dispersion strengthening and crystallizationwithin the matrix .
Flexural strength is 131 MPa Doubled upto 269 MPa by the addition of glaze.
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All Ceramics Dr. Nithin Mathew
Advantages
62
Increased co-efficient of thermal expansion
Improved strength (glass infiltration of magnesia core)
High expansion property
All Ceramics Dr. Nithin Mathew
LEUCITE-REINFORCED PORCELAIN
They are feldspathic porcelains, dispersion strengthened by crystallization of leucite crystalsin the glass-matrix.
The leucite and glassy components are fused during the baking process at 10200C.
Leucite crystals in the glass - matrix (50%).
Strength : Nucleation and growth of leucite crystals.
Translucency : Closeness of the refractive index of leucite with that of the glass matrix.
Flexure strength : approximately 140 MPa.63
All Ceramics Dr. Nithin Mathew
DisadvantagesAdvantages
High strength (leucite reinforcement)
Good translucency
Moderate flexural strength
64
Marginal inaccuracy due to sinteringshrinkage.
Fracture in posterior teeth.
High abrasive effect on opposing teeth.
All Ceramics Dr. Nithin Mathew
INFILTRATED / SLIP CAST CERAMICS
All Ceramics Dr. Nithin Mathew
GLASS INFILTRATED CORE CERAMICS Inceram Alumina Inceram Spinel Inceram Zirconia
2 components : Powder & Glass
Fabrication: Powder mixed with water to form suspension called SLIP SLIP is painted onto refractory die : absorbs water leaving solid alumina Baked at 11200C for 10 hours : opaque, porous core Glass powder applied to core and fired at 11000C for 3-4hrs Molten glass infiltrates the porous alumina or spinel by capillary action Veneering
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All Ceramics Dr. Nithin Mathew
Die preparation Mixing aluminous powder with water to produce slip
The slip is painted onto the die with a brush
The water is removed by the capillary action of the
porous gypsum, which packs the particles into a
rigid porous network
Sintering : 10 Hrs 11200C
Porous network
All Ceramics Dr. Nithin Mathew
Glass powder is used to fill the pores in the alumina core.
Glass Infiltration (4hrs 11000C)Glass becomes molten and flows into the
pores by capillary diffusion
Removal of excess glass Veneering with esthetic porcelain
All Ceramics Dr. Nithin Mathew
The internal surface is sandblasted (with 50 A12O3)
Since the density of In-ceram core makes conventional methods of etching with HF acid
ineffective for bonding with a resin-cement.
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INCERAM ALUMINA
Developed by a French scientist and dentist Dr. Michael Sadoun (1980) and first introduced in
France in 1988.
Composition:
Two three-dimensional interpenetrating phases :
Alumina/ Al2O3 crystalline : 99.56 wt%
An Infiltration of glass lanthanum aluminosilicate
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Lanthanum
Decreases the viscosity of the glass to assist infiltration
Increases its refractive index to improve translucency.
Fabrication stages :
Slip casting Veneering of core
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PROPERTIES
STRENGTH :
Densely packed crystalline particles (70% alumina) limit crack propagation and prevent
fracture.
Flexure strength : 450 MPa range
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All Ceramics Dr. Nithin Mathew
PROPERTIES
COLOR :
Final color : influenced by the color of the alumina core (opaque).
Colorants used : transitional metal ions incorporated into the glass structure itself
Spinel ceramic : the core is more transparent and its corresponding infiltration glass is slightlytinted.
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All Ceramics Dr. Nithin Mathew
DisadvantagesAdvantages
Minimal firing shrinkage, hence an
accurate fit.
High flexure strengths (3 times)
Aluminous core (opaque) : used to cover
darkened teeth or post/ core.
Wear of opposing teeth is lesser
Biocompatible : less plaque accumulation.
74
Requires specialized equipment.
Poor optical properties or esthetics
(opaque alumina core)
Incapability of being etched
Slip casting is a complex technique
Considerable reduction of tooth surface
All Ceramics Dr. Nithin Mathew
IN-CERAM SPINELL
Introduced due to the comparatively high opacity of the alumina core.
Incorporating magnesium aluminate (Mg A12O4) results in improved optical properties
characterized by
Increased translucency
About 25% reduction in flexural strength
Spinel or Magnesium aluminate (Mg A12O4) is a composition containing A12O3 and Mg2O.
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All Ceramics Dr. Nithin Mathew
DisadvantagesAdvantages
Spinel renders greater strength
characteristics.
Spinell has extended uses (Inlay / Onlay,
ceramic core material and Veneers.)
76
Incapable to be etched by HF
25% reduction in flexural strength.
All Ceramics Dr. Nithin Mathew
IN-CERAM ZIRCONIA
A mixture of zirconium oxide / aluminium oxide is used as a framework material,.
Physical properties were improved without altering the proven working procedure.
The final core of ICZ consists of
30 wt% zirconia
70 wt% alumina.
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DisadvantagesAdvantages
High flexural strength
1.4 times the stability
2-3 times impact capacity compared to
ln-Ceram Alumina
Excellent Marginal Accuracy
Biocompatibility
78
Poor esthetics due to increased opacity
Inability to etch
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79
CASTABLE CERAMICS
All Ceramics Dr. Nithin Mathew
Introduced by Mc Culloch in 1968
Di-Cor New types
Cera pearl Canasite glass ceramic Optimal pressable ceramic Olympus castable ceramics Castable phosphate glass ceramic
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Supplied as ceramic ingots
Fabricated using Lost Wax technique and Centrifugal casting technique
Steps: Wax pattern invested Dewaxing Molten glass cast into mould using centrifugal casting machine Glass core : ceramming (heat treatment process)
Microscopic plate-like crystals grow within the glass matrix Veneered using feldspathic ceramics : Dicor Plus
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DI-COR (Dentsply + Corning Glass Co)
First commercially available castable ceramic material.
Non porous, non homogenous, microstructure with uniform crystal size which is derived from
the controlled growth of crystals within an amorphous matrix of glass.
Dicor composed of:
Tetrasilicic fluormica crystals : 55 % Glass ceramic : 45 %
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Major Ingredients Minor Ingredients
SiO2 : 45-70%
K2O : upto 20%
MgO : 13-30%
MgF2 (nucleating agent)
A12O3 : upto 2% (durability & hardness)
ZrO2 : upto 7%
Fluorescing agents (esthetics)
BaO : 1 to 4% (radiopacity)
Supplied as :
Special Dicor casting crucibles, 4.1 gm Dicor glass ingot
Dicor shading porcelain kit.
All Ceramics Dr. Nithin Mathew
PROPERTIES
Flexural strength : 81 6.8 Mpa
Strength : 440-505 KHN
Biocompatible
Less bacterial counts : smooth surface, low surface tension, fluoride content.
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All Ceramics Dr. Nithin Mathew
PROPERTIES
Esthetics :
Gross man and Adiar Hue and chroma of metal ceramics and Castable ceramics matched natural teeth.
Value of only Castable ceramics matched natural teeth.
Presence of mica crystals scatter light similar to enamel rods.
Chameleon effect i.e. the restoration acquires a part of the color from adjacent teeth andfillings as well as the underlying cement lute.
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All Ceramics Dr. Nithin Mathew
PROPERTIES
Cementation : Zinc phosphate, light activated urethane resin Etching with ammonium difluoride for 2 min (Bailey & Bennet 1988)
Survival rate : Kenneth et al 1999 - 14yr study
Crowns : 82% Cores : 100% Inlay and onlay : 90% Partial coverage : 92%
Expenstein et al 2000 : Posterior 70%, anterior 82.7%
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All Ceramics Dr. Nithin Mathew
DisadvantagesAdvantages
Chemical and physical uniformity.
Excellent marginal adaptation
Compatibility with lost-wax castingprocess.
Ease of adjustment
Low thermal conductivity
Radiographic density is similar to that ofenamel
87
Requires special equipments
Veneers failure rate as high as 8%
Must be stained with low fusing feldspathicporcelain
All Ceramics Dr. Nithin Mathew
CASTABLE APATITE GLASS CERAMIC (CERAPEARL)
1985 -Sumiya Hobo & Iwata
Available as Cera Pearl
Crystalline microstructure similar to natural enamel
Mechanical properties superior to enamel
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Composition
CaO : 45% - reacts with P2O5
P2O5 : 15% - Aids in glass formation
SiO2 : 35% - Forms the glass matrix.
MgO : 5% - Decreases the viscosity (anti flux)
Other : Trace elements (Nucleating agents during ceramming)
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CHEMISTRY
90
CaPO41460C
1510CAmorphous
Mass750C
870CCrystalline Oxyapatite
Exposed to moisture
HydroxyApatite
Ceramming
Ceramming :
The ceramming oven is preheated at 750C for 15 minutes. After the cast glass ceramic isplaced in the oven the temperature is raised at the rate 500C / min until it reaches 870C and heldfor 1 hr.
External staining : Cerastain ( Bioceram )
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PROPERTIES
Cerapearl is similar to natural enamel in Composition
Density : 2.97 gm/cm2 Refractive index : 1.66 Thermal conductivity : 0.002 Hardness : 343
Clinical success : (crowns) 2 year success rate 100%
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PRESSABLE CERAMICS
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Supplied as ceramic ingots
Fabricated using Lost Wax technique and heat pressed into the mould
Steps: Wax pattern invested in phosphate bonded investment Placed in specialized mould with alumina plunger After burnout, ceramic ingot is placed under plunger and heated to 11500C Veneered using feldspathic ceramics
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CLASSIFICATION
Shrink free ceramics Cerestore Al-ceram
Leucite reinforced glass ceramics IPS empress Optec/OPC
Lithia reinforced glass ceramic IPS empress 2 OPC 3G
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CERESTORE (Shrink Free Ceramics)
Consists of Al2O3 and MgO mixed with Barium glass frits.
On firing crystalline transformation produces Magnesium aluminate spinel, which occupies a
greater volume than the original mixed oxides compensates for the conventional firing
shrinkage.
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Unfired Cerestore core : Al2O3 MgO Glass frit Silicone resin Fillers
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Fired Cerestore core : - Al2O3 (Corrundum) MgAl2O4 (Spinel) Ba Mg2Al3 (Si9Al2O3) Barium osumilite
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Chemical And Crystalline Transformation
Silicone Resin SiO SiO2 Alumina Aluminosilicate(160-8000C)
(900-13000C)
Al2O3 + MgO MgAl2O4 (decreased shrinkage )
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PROPERTIES
Flexural strength : 225 Mpa
Fit : exceptional fit because of direct moulding process.
Low thermal conductivity
Radiodensity similar to enamel
Biocompatible
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Advantages
Dimensional stability of the core material in the molded (unfired) and fired states
Better accuracy of fit and marginal integrity
Esthetics
Biocompatible (inert) and resistant to plaque formation (glazed surface)
Radio density similar to that of enamel
Low thermal conductivity; thus reduced thermal sensitivity
Low coefficient of thermal expansion and high modulus of elasticity results in protection ofcement seal
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Disadvantages
Complex
Specialized laboratory equipment and cost
Inadequate flexural strength compared to the metal-ceramic restorations
Poor abrasion resistance, hence not recommended in patients with heavy bruxism orinadequate clearance
LIMITATIONS and high clinical failure rates of the Cerestore led to the withdrawal of this
product from the market.
Improved version : 70 to 90% higher flexural strength - marketed as Al Ceram.
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IPS-EMPRESS
Hot pressed ceramics
2 types:
Leucite reinforced (K2O Al2O3 4 SiO2)
Lithium Disilicate reinforced (SiO2 LiO2 P2O5 ZrO2)
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COMPOSITION
Pre cerammed, pre colored : INGOTS SiO2 : 63% Al2O3 : 17.7% K2O : 11.2% Na2O : 4.6% B2O3 : 0.6% CaO : 1.6% BaO : 1.6% TiO2 : 0.2%
Contains higher concentration of leucite crystals, which increases the resistance to crackpropagation
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Leucite content
Conventional Porcelain Dicor
IPS Empress Pressable ceramic
30-35% 50-60% 80-85%
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FABRICATION
Lost-wax technique:
Wax pattern is invested
Burnout (at 850C)
The ceramic ingot plunger and the entire assembly is
preheated to 11000C
After 20 minute holding time the plunger presses the ceramic
under vacuum (0.3-0.4 MPa) into the mould
Held under pneumatic pressure (45-mins) to allow complete
and accurate fill of the mould.103
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PROPERTIES
Flexural strength : 160-180 Mpa
The increase in strength has been attributed to : Pressing step which increases the density of leucite crystals Subsequent heat treatments which initiate growth of additional leucite crystals
Esthetics : High esthetic value (translucent, fluorescent) Clinical survival :
95% survival rate of 2-4 years (Deniz G et al 2002)
Marginal adaptation : Better marginal adaptation compared to aluminous core material.
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Advantages
Lack of metal or an opaque ceramic core
Moderate flexural strength (160-180 MPa)
Excellent fit (low-shrinkage ceramic)
Improved esthetics (translucent, fluorescent)
Etch-able
Less susceptible to fatigue and stress failure
Less abrasive to opposing tooth
Biocompatible material
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Disadvantages
Potential to fracture in posterior areas.
Special laboratory equipment such as pressing oven and die material (expensive)
Inability to cover the color of a darkened tooth preparation or post and core, since the crownsare relatively translucent.
Compressive strength and flexural strength lesser than metal-ceramic or glass-infiltrated (In-Ceram) crowns.
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IPS EMPRESS 2 (IVOCLAR)
Second generation of pressable materials for all- ceramic bridges.
Lithium disilicate crystal >60vol%.
The apatite crystals are layered which improved optical properties (translucency, light
scattering) which contribute to the unique chameleon effect.
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IPS Empress IPS Empress 2
Flexural strength Upto 150 MPa > 400 Mpa
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Other applications : Core build-up system with the pre-fabricated zircon oxide root canal posts
Advantages
High biocompatibility Excellent fracture resistance High radiopacity Outstanding translucency
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IPS E.MAX PRESS
Introduced in 2005.
Considered as an enhanced lithium disilicate press-ceramic material when compared to
Empress II.
Better physical properties and improved esthetics
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Strength
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MACHINABLE CERAMICS
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Impression
Casts & Die
Wax Pattern
Investing
Casting
Lost Wax Technique
Camera Contact Digitizer
Laser
Machine Sinter
Computerised Design
CAD / CAM System
Traditional Technique Higher Technology
Data Acquisition
Restoration Design
Restoration Fabrication
Electrical Discharge Machine
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Application of CAD/ CAM techniques was actively pursued by three groups of researches
Group supported by Henson International of France.
Combined group effort between the University of Zurich and Brains, BrandestiniInstruments of Switzerland.
University of Minnesota, supported by the U.S. National Institute of Dental Research.
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FRENCH SYSTEM
Optical impression Laser scanner Data processing By Shape recognition software It has a library (memory) describing theoretical teeth.
The system uses: 3-D probe system based on electro-optical method Surface modelling and screen display Automatic milling by a numerically controlled 4-axis machine
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SWISS SYSTEM
Optical impression - Optical topographic scanning using a 3-D oral camera Data processing - By an interactive CAD unit
The system uses: A desk top model computer Display monitor permitting visual verification of quality of data being acquired Electronically controlled 3-axis milling machine
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MINNESOTA SYSTEM
Optical impression - Photograph based system using a 35-mm camera with magnifying lens.
Data processing - Data obtained in the dental office is sent to another location for processingand machining.
3-D Reconstruction uses : Direct line transformation and an alternative technique proposed by Grimson
Milling with a 5-axis milling machine
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CLASSIFICATION - Machinable Ceramics
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ANALOGOUS SYSTEM DIGITAL SYSTEMS
I. Direct
II. Indirect
i. 3-D scanning
ii. CAD modelling
iii. Fabrication
I. Copy milling
i. Fabrication of prototype for scanning
ii. Copying and reproduction by milling
II. Erosive techniques
i. Sono Erosion
ii. Spark Erosion
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FINE SCALE FELDSPATHIC PORCELAIN
I. CEREC VITABLOC MARK I:
Feldspathic porcelain Larger particle size (10-50 micron)
II. CEREC VITABLOC MARK II:
Feldspathic porcelain reinforcedwith aluminium oxide (20-30%)
Fine grain size (4 micron)
GLASS PORCELAIN
I. DICORFlurosilica Mica Crystals Plates (2 microns)
II. MGC F
Tetrasilica mica(enhance fluorescence, machinability)
III. PRO CAD
Leucite - Reinforced Glass Ceramic
(high strength)118
2 Classes of Machinable Ceramics
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DIGITAL SYSTEMS
CAD-CAM:
Uses digital information about the tooth preparation or a pattern of the restoration to provide
a computer-aided design (CAD) on the video monitor for inspection and modification.
The image is the reference for designing a restoration on the video monitor.
Once the 3-D image for the restoration design is accepted, the computer translates the image
into a set of instructions to guide a milling tool [CAM] in cutting the restoration from a block of
material.
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STAGES OF FABRICATION
All systems ideally involve 5 basic stages:
1. Computerized surface digitization
2. Computer - aided design
3. Computer - assisted manufacturing
4. Computer - aided esthetics
5. Computer - aided finishing
The last two stages are more complex and are still being developed for including incommercial systems.
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Scanning 3D Miniature Camera
Microprocessor unit stores the pattern
Video display serves as a format for manual construction
Final 3-D restoration is developed from above again bymicroprocessor
CAD-CAM Procedure (10-15mins)
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Electronic information is transferred to miniature multiple axis milling device
Milling device generates a precision fitting restoration from a standard ceramic block
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CEREC SYSTEM
Brains. A. G, Switzerland in 1980 Manufactured in West Germany, Siemens group
Consists of: 3-D video camera (scan head) Electronic image processor with memory unit Digital processor Miniature Milling machine
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DisadvantagesAdvantages
Translucency and color of porcelain veryclosely to natural dental tissues
Quality of ceramic is not changed duringprocessing
Can be placed in one visit
Prefabricated ceramic is wear resistant
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Occlusal anatomy to be developed
Inaccuracies in fit
Poor esthetics systems
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CEREC 2 SYSTEM
Morman & Brandestini in 1994 Constant further development
Major changes include: Enlargement of grinding unit from 3 to 6 axes Sophisticated software technology : occlusal surfaces
Minor technical innovations: Magnification factor increased from 8x to 12x Improved grinding precision by 24 times Improved accuracy of fit
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CEREC 3 SYSTEM
Operator can record multiple images in seconds
Creates a virtual cast for entire quadrant
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OTHER DIGITAL SYSTEMS
DURET SYSTEM Francois Duret : produced by Sopha (France)
CICERO SYSTEM
COMET SYSTEM
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ADVANTAGES : Machinable Ceramics
Single visit
Good patient acceptance
Eliminates procedures like impression model making and fabrication of temporary prosthesis
Void free porcelains without firing shrinkage
Better adaptation
Inlay,onlay can be fabricated chair side
Eliminates asepsis
Since its computer assisted crowns of correct dimensions can be obtained
Glazing is not required : can be polished
Less abrasion of tooth structure : homogenous material128
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DISADVANTAGES : Machinable Ceramics
Limitations in fabrication of multiple units
Inability to characterize shades and translucency
Inability to image in wet environment
Technique sensitive
Expensive
Limited availability
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ANALOGUS SYSTEMS : COPY MILLING
CELAY SYSTEM
Switzerland in 1992
High precision manually operated
Key duplication
Advantage : Recreation of all surfaces.
130
COPYING SIDE Various size probes represent
size of diff milling burs is runover surface of pattern
MILLING SIDE At same time matched rotary
instru-mills same shape out ofrestorative block
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ANALOGUS SYSTEMS : EROSIVE TECHNIQUES
SONO EROSION:
Based on ultrasonic methods.
The ceramic blank is surrounded by an abrasive suspension of hard particles, such as boron
carbide, which are accelerated by ultrasonics, and thus erode the restoration out of the
ceramic blank.
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ANALOGUS SYSTEMS : EROSIVE TECHNIQUES
SPARK EROSION:
'Electrical Discharge Machining' (EDM)
Metal removal process using a series of sparks to erode material from a workpiece in a liquid
medium under carefully controlled conditions.
Liquid medium : light oil called the dielectric fluid.
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CERCON & LAVA ZIRCONIA CORE CERAMICS
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Fabrication
Tooth preparation
Impression made
Wax pattern made on
model
Anchored on to the Cercon
Brain
Presinteredzirconia blank
attached on other side of brain unit
Unit activatedPattern scanned
Milled prosthesis then removed from unit and placed in the
cercon furnace (13500C for 6 hrs)
TrimmingFinished
ceramic core framework
Veneering
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BONDING OF PORCELAINS
RESINCERAMIC BONDING
Function of the silane primer between porcelain and the composite resin plays an important
role.
Etching of ceramic surface with 7.5 to 10% hydrofluoric acid for 2-10mins and then followed
by silanization increased the bond strength to porcelain (Peremuter and Montagonon, 1981)
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METAL-CERAMIC BONDING
1. Chemical bonding across the metal-porcelain interface:
Diffusion between surface oxide on the alloy and ceramic
2. Mechanical interlocking:
Due to surface irregularity of the alloy Air abrasion with aluminium oxide particles
3. Residual compressive stresses:
Core has slightly higher CTE than porcelain Porcelain draws towards the coping on cooling : residual compressive forces
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REPAIR OF CERAMIC RESTORATIONS
1. PORCELAIN REPAIR :
Fracture is totally in porcelain
Simplest repair
Preparation of porcelain surface by bonding :
Surface roughening by using diamond burs, air abrasion and acid etching with 9.5% HF acid
Application of silane coupling agent & allowed to dry for 1 min.
Application of bonding agent
Shade matched composite
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2. MIXED (PORCELAIN/METAL ) REPAIR :
Involves exposed metal
More complicated
If remaining porcelain:
Adequate : exposed metal and remaining porcelain is veneered with compositeopaquer & subsequently with layers of shade matched composite.
Inadequate : exposed metal surface is used as an adhesive substrate afterpreparation for bonding with composite opaquer layer followed by shade matched
composite.
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3. METALREPAIR:
Involves the exposed metal with or no remaining porcelain
Most difficult
2 methods :
Veneering exposed metal surface with direct bonding of shade matched composite
after preparation of exposed metal surface for bonding.
Fabrication of an over casting: small areas of remaining porcelain are removed if
present. Crown / pontic is reduced circumferentially to provide room for both
porcelain and metal, & provide margin for the laboratory technician and a thin metal
overcasting with fused porcelain veneer is fabricated.
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OTHER APPLICATIONS OF CERAMICS
ALL CERAMIC POST & CORES
DRAWBACKS of conventional Metal Post & Core
Decrease depth of translucency of restoration
Shine through in cervical root, altering appearance of thin gingival tissue
Corrosion products
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ADVANTAGES of All-ceramic Post & Core
All ceramic restoration transmits certain percentage of incident light to ceramic core & post .
Color of final restoration will be derived from an internal shade
Depth of translucency in cervical root area
Biocompatible
MATERIALS USED Inceram Dense sintered alumina ceramic Zirconium oxide ceramics
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CERAMIC-DENTAL IMPLANTS
Ceramic oxides : resistant to corrosion Tissue grow into surface porosity Ceramic Coating for Implant
Bioactive Ceramics : High density Alumina, TriCalcium Phosphate, High Alumina polymercomposite
Inert Ceramics : Alumina, Zirconium Oxide
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CERAMIC INSERTS
Megafillers for direct posterior composite restorations Reduce bulk of composite resin Decrease shrinkage Minimize wear
Composition
Glass inserts Lithium alumino-silicate glass (heat treated & silanated)
eg: Beta Quartz Glass ceramic inserts
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CEROMERS
Ceramics + Polymers = Ceromers
Ceramics: Abrasion resistance High stability Esthetics
Composites Ease of final adjustments Excellent polishability Bonding with luting cement Possibility of repair
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ZIRCONIA IMPLANTS
A radical new solution to immediate dental implant placement.
Patients extracted tooth is laser scanned and modified in CAD
software
Machined out of zirconium
Implanted in the still healing socket
Provides incredibly natural looking results.
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An increase of the crystalline content as seen in the pressable materials and the fully sintered
zirconia generally corresponds to an improvement of the mechanical properties.
An increase of crystalline content of a glassceramic is accompanied with an increase of the
strength and fracture toughness.
146
Strength, Fracture Toughness and Microstructure of a Selection of All-Ceramic Materials. Part I. Pressable and Alumina Glass-Infiltrated Ceramics
Part II. Zirconia-based dental ceramicsGuazzatoa, Mohammad Albakrya, Simon P. Ringerb, Michael V. Swain
Dental Materials (2004) 20, 441448
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Vita Inceram crowns exhibited significantly higher fracture strength than conventional all-
ceramic crowns.
147
An Evaluation of Two Modern All-Ceramic Crowns and their comparison withMetal Ceramic Crowns in terms of the Translucency and Fracture Strength
Girish Nazirkar, Suresh Meshram
International Journal Of Dental Clinics 2011:3(1):5-7
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The fracture strength of monolithic high translucent zirconia crown is considerably higherthan that of porcelain-veneered zirconia crown cores, porcelain-veneered high translucent
zirconia crown cores and monolithic lithium disilicate crowns.
148
Fracture strength of monolithic all-ceramic crowns made of high translucent yttrium oxide-stabilized zirconium dioxide compared to porcelain-veneered crowns and
lithium disilicate crownsCamilla Johansson, Gratiela Kmet, Johnny Rivera, Christel Larsson & Per Vult Von Steyern
Acta Odontologica Scandinavica 2014; 72: 145-153
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Lithium Disilicate glass-ceramic restorations had higher fracture resistances than leucite
reinforced glass-ceramic restorations.
149
Dynamic fatigue and fracture resistance of non-retentive all-ceramic full-coverage molar restorations. Influence of ceramic material and preparation design
Jan-Ole Clausen, Milia Abou Tara, Matthias KernDental Materials 26 (2010) 533538
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Observations regarding zirconia-based all ceramic restorations compared with PFM restorations:
Better esthetically than typical PFM restorations
Long-term color stability probably will be the same as that with PFM restorations
Margins of the restorations have a more acceptable appearance than those of PFM.
Strength and service record of PFM restorations and zirconia based restorations in three-unit
prostheses is similar.
Gingival sensitivity to metal will be reduced or eliminated with use of zirconia-based.150
Choosing an all-ceramic restorative materialPorcelain-fused-to-metal or zirconia-based?
Gordon J. Christensen
JADA, Vol. 138; May 2007
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SELECTION OF CERAMIC MATERIALS
Four broad categories or types of ceramic systems:
Category 1: Powder/liquid feldspathic porcelains
Category 2: Pressed or machined glass-ceramics
Category 3: High-strength crystalline ceramics
Category 4: Metal ceramics
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Ceramics: Rationale for material selection, Cosmetic Dentistry:2,2013
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Clinical Parameters To Evaluate :
Individual teeth evaluated for specific material selection Assessing four environmental conditions in which the restoration will function
1. Substrate
2. Flexure risk assessment
3. Excessive shear and tensile stress risk assessment
4. Bond/seal maintenance risk assessment
Ceramics: Rationale for material selection, Cosmetic Dentistry:2,2013
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1. Substrate
Is it enamel? How much of the bonded surface will be enamel? How much enamel is on the tooth? How much of the bonded surface will be dentine? What type of dentine will the restoration be bonded to? Is it a restorative material (e.g.
composite, alloy)?
High bond strength : Enamel
Dentine surfaces/composite : Less predictable
More stress - between dentine and composite - more damage to the restoration andunderlying tooth structure
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2. Flexure risk assessment
Each tooth and existing restorations are evaluated for signs of past overt tooth flexure.
Signs
Excessive enamel crazing
Tooth and restoration wear
Tooth and restoration fracture
Micro-leakage at restoration margins
Recession
Abfraction lesions
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2. Flexure risk assessment
Low risk Low wear; minimal to no fractures or lesions Patients oral condition is reasonably healthy
Medium risk Signs of occlusal trauma Mild to moderate gingival recession along with inflammation Bonding mostly to enamel is still possible There are no excessive fractures
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2. Flexure risk assessment
High risk Evidence of occlusal trauma from parafunction; More than 50 % of dentine exposure exists Significant loss of enamel due to wear of 50 % or more Porcelain must be built up by more than 2 mm.
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3. Excessive shear and tensile stress risk assessment
All types of ceramics (especially porcelains) are weak in tensile and shear stresses.
Ceramic materials perform best under compressive stress
If a high-stress field is anticipated : Stronger and tougher ceramics are needed
The substructure should reinforce the veneering porcelain by utilising the reinforced-porcelain system technique
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4. Bond/seal maintenance risk assessment
Glass-matrix materials : powder/liquid porcelains and pressed or machined glass-ceramics,
require maintenance of the bond and seal for clinical durability.
If the bond and seal cannot be maintained, then high-strength ceramics or metal ceramics are
the most suitable, since these materials can be placed using conventional cementation
techniques.
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4. Bond/seal maintenance risk assessment
Clinical situations in which the risk of bond failure is higher are
Moisture control problems
Higher shear and tensile stresses on bonded interfaces
Variable bonding interfaces (different types of dentine)
Material and technique selection of bonding
The experience of the operator
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Category 1: Powder/Liquid Feldspathic Porcelains
Aesthetic Factors 0.20.3 mm is required for each shade change
Substrate Condition 50 % or more remaining enamel on the tooth 50 % or more of the bonded substrate is enamel 70 % or more of the margin is in enamel
Flexure risk assessment Higher risk and more guarded prognosis when bonding to dentine Increased enamel, prognosis improved Depending on the dentine/enamel ratio, the risk : low to moderate
Tensile and shear stress risk assessment
Low to low/moderate risk. Large areas of unsupported porcelain, deep overbite or overlap of
teeth, bonding to more-flexible substrates : Increase the risk of exposure to shear and tensile stresses
Bond/seal maintenance risk assessment
Absolute low risk of bond/seal failure
Indications Indicated for anterior teeth
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Category 2: Pressed or Machined Glass-ceramics
Aesthetic Factors Minimum working thickness of 0.8 mm 0.20.3 mm for each shade change is required
Substrate Condition Less than 50 % of the enamel on the tooth Less than 50 % of the bonded substrate is enamel 30 % or more of the margin is in dentine
Flexure risk assessment Risk is medium for Empress, VITABLOCS Mark II and Authentic-type glass-ceramics and layered IPS e.max
Tensile and shear stress risk assessment
Flexure risk is medium to high (and full crown preparation is not desirable)
Monolithic IPS e.max has been 100 % successful for as long as 30 months in service.
Bond/seal maintenance risk assessment
Risk is medium for Empress, VITABLOCS Mark II and Authentic-type glass-ceramics, and layered IPS e.max.
Medium to medium/high for bonded monolithic IPS e.maxIndications Thicker veneers, anterior crowns, and posterior inlay and onlays
Only indicated in clinical situations in which long-term bond and seal can be maintained.
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Category 3: High-strength Crystalline CeramicsAesthetic Factors Minimum working thickness of 1.2 mm is required.Substrate Condition Substrate is not critical, since a high-strength core supports veneering
material.Flexure risk assessment Risk is high or low
For high-risk situations, core design and structural support for porcelain become more critical
Tensile and shear stress risk assessment
Risk is high or low High-risk situations : Preparations should allow for a 0.5 mm core
plus 1 mm of porcelain Anteriors: There should not be more than 2 mm of unsupported incisal
porcelain. Molars : Better to use zirconia cores rather than alumina cores High risk molar : Full-contour zirconia restorations recommended.
Bond/seal maintenance risk assessment
If the risk of obtaining or losing the bond or seal is high, then zirconia is the ideal all-ceramic to use.
Indications When significant tooth structure is missing Unfavourable risk for flexure and stress distribution is present It is impossible to obtain and maintain bond and seal
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Category 4: Metal ceramicsAesthetic Factors 1.51.7 mm is required for maximum aestheticsSubstrate Condition Substrate is not as critical, since the metal core supports the
veneering material.Flexure risk assessment Risk is high or low
For high-risk situations, core design and structural support for porcelain become more critical
Tensile and shear stress risk assessment
Risk is high or low For high-risk situations, core design and structural support for
porcelain become more criticalBond/seal maintenance risk assessment
If the risk of obtaining or losing the bond or seal is high, then metal ceramics are an ideal choice for a full-crown restoration.
Indications Indicated in all full-crown situations, esp when all risk factors are high.
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CONCLUSION
Dental ceramic technology is one of the fastest growing areas of dental material research and
development. The past decades have seen the development of several new groups of ceramics.
Each system has its own merits, but may also have shortcomings.
Combinations of materials and techniques are beginning to emerge which aim to exploit the
best features of each.
Glass-ceramic and glass-infiltrated alumina blocks for CAD-CAM restoration production are
examples of these.
The diversity and sophistication of the CAD-CAM systems may prove to be influential in the
future.164
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REFERENCES
Philips science of dental materials - Anusavice
Craigs restorative materials
Dental materials & their selection - William O Brien
Clinical operative dentistry - principles and practice - Ramya Raghu
Textbookof Dental materials Mahalekshmi
Theory and practice of fixed prosthodontics - Tylmann
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All Ceramics Dr. Nithin Mathew 167
Slide Number 1All ceramics(Material Aspect)Contents introductionSlide Number 5Slide Number 6TerminologiesSlide Number 8Slide Number 9Slide Number 10historySlide Number 12Slide Number 13classificationFIRING temperatureFabrication techniqueTranslucencyCOMpositionAccording To SystemsSlide Number 20Composition of Dental CeramicsSlide Number 22PIGMENTSAdvantages of Dental CeramicsdisadvantagesManufacturing of ceramicsManufacturing of ceramicsSlide Number 28Manufacturing of ceramicsSlide Number 30dispensingFabrication of CERAMIC RESTORATIONSSlide Number 33Slide Number 34Slide Number 35Slide Number 36Slide Number 37Stages of Maturity of Porcelain during FiringSlide Number 39Stages of maturitySlide Number 41Porcelain Surface TreatmentInstrumentation for Finishing and Polishing Ceramic RestorationsMethods of Strengthening Ceramics1. Minimize the effect of stress raisers2. Develop residual compressive stresses3. Minimize the number of firing cycles4. Ion exchange/ Chemical tempering5. Thermal Tempering6. Dispersion Strengthening7. Transformation TougheningAll ceramic systemsConventional ceramics(powder slurry)Slide Number 58Aluminous core porcelainSlide Number 60 Magnesia Reinforced PorcelainAdvantagesLeucite-reinforced porcelainSlide Number 64INFILTRATED / slip cast CERAMICSSlide Number 66Slide Number 67Slide Number 68Slide Number 69 INCERAM ALUMINASlide Number 71PropertiesPropertiesSlide Number 74 IN-CERAM SPINELLSlide Number 76 IN-CERAM ZIRCONIASlide Number 78castable CERAMICSSlide Number 80Slide Number 81DI-COR (Dentsply + Corning Glass Co)Slide Number 83propertiespropertiespropertiesSlide Number 87CASTABLE APATITE GLASS CERAMIC (CERAPEARL)Slide Number 89ChemistrypropertiesPRESSABLE CERAMICSSlide Number 93Classification CERESTORE (Shrink Free Ceramics)Slide Number 96Chemical And Crystalline TransformationPropertiesAdvantagesDisadvantagesIPS-EMPRESSCOMPOSITIONfabricationpropertiesAdvantagesDisadvantagesIPS EMPRESS 2 (Ivoclar)Slide Number 108IPS E.max pressStrengthmACHINABLE CERAMICSSlide Number 112Slide Number 113French systemSwiss systemMinnesota systemCLASSIFICATION - Machinable Ceramics2 Classes of Machinable CeramicsDIGITAL SYSTEMSStages of fabricationSlide Number 121Slide Number 122Cerec systemSlide Number 124CEREC 2 SYSTEMCerec 3 systemOTHER DIGITAL SYSTEMSAdvantages : Machinable CeramicsdisAdvantages : Machinable CeramicsANALOGUS SYSTEMS : COPY MILLINGANALOGUS SYSTEMS : Erosive techniquesANALOGUS SYSTEMS : Erosive techniquesCercon & lava zirconia core ceramicsBonding of porcelainsSlide Number 135Repair of ceramic restorationsSlide Number 137Slide Number 138Other applications of ceramicsSlide Number 140Slide Number 141Slide Number 142Slide Number 143Slide Number 144Slide Number 145Slide Number 146Slide Number 147Slide Number 148Slide Number 149Slide Number 150Selection of Ceramic materialsSlide Number 152Slide Number 153Slide Number 154Slide Number 155Slide Number 156Slide Number 157Slide Number 158Slide Number 159Slide Number 160Slide Number 161Slide Number 162Slide Number 163conclusionSlide Number 165referencesSlide Number 167