Dental ceramics/certified fixed orthodontic courses by Indian dental academy

DENTAL CERAMICSDENTAL CERAMICS
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INDIAN DENTAL ACADEMY
Leader in continuing Dental Education

Introduction
History
Composition
Classification of Ceramics
According to applications
According to the firing temperatures
According to use
According to method of fabrication
According to method of firing

Manufacture and dispensing of dental ceramics
Steps in fabrication
Condensation
Instruments
Methods
Sintering
Steps
Stages of maturity
Types
Ceramic furnaces

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Glazing
Add on self glazing
Internal staining
Cooling
Bonding to porcelain
Etching of ceramic surface
Silanization
Ceramics bonding systems
Silane coupling agent

Properties of dental ceramics
Feldspathic porcelain
Non reinforced
Reinforced
High fusing porcelains
Medium fusing porcelain
Low fusing porcelains

Metal ceramic systems
•Rationale, fabrication and technical procedure
• Terminology
•Requisites of metal ceramic system
* Metal ceramic alloys
Classification
High noble
Noble alloys
Base metal alloys

Metal ceramic veneer porcelains
•Manufacture
•Types
•Metal ceramic bonding
• Methods of attaching porcelain to metal
* Bonding by atypical methods
* Electrodeposition

•Methods for bonding using resin bonding
* Surface conditioning methods
* Chemical etching
Non-cast metal ceramics systems
Foil crown system
- Renaissance system
- Captek system.
- Ceptalec system
- Sunrise system
Galvanoceramic restorations

All ceramic systems.
•Newer types of all ceramic restorative materials
• Conventional Powder / slurry ceramics
Alumina – reinforced porcelain (aluminous porcelain)
- Aluminum core porcelain
- Aluminum veneer porcelain
Magnesia – reinforced porcelain.
Leucite reinforced
Low fusing ceramics (example hydrothermal ceramics) –
Duceram LFC.

Castable ceramics
* Types
- Fluoromicas.- DICOR
- Apatite glass ceramics
cerapearl
- Other glass ceramics
Lithia based glass ceramic
CaPO4 glass ceramics
Advantages

Machinable ceramics
* Digital systems (CAD/CAM)
CEREC systems
CICERO system
COMET system
Other digital systems
Advantages and disadvantages
•Analogous systems.
* Copy milling
* Erosion methods
- Sono erosion
- Spark erosion
* Celay system
* Procera system
* Other copying systemswww.indiandentalacademy.comwww.indiandentalacademy.com

Pressable ceramics
* Cerestore
* Leucite reinforced glass ceramics
* IPS empress
* OPTEC (Optimal pressable ceramic / OPC)
* IPS empress 2
Infiltrated ceramics
* In ceram (Glass infiltrated ceramic core)
* In-ceram spinel
* In-ceram zirconia
* Procera
* Copy milling In-ceram alumina

Extended and Innovative applications of
ceramics in dentistry
•Esthetic posterior restorations
* All ceramic
- Fixed ceramic over refractory die
- Cast glass ceramic restoration
- The heat pressed ceramic
- Slip casting
- Machined ceramic
* All ceramic post and cores
- Advantages
- Dental ceramic materials used
Conventional dental ceramic
High toughness ceramics
- In ceram and Procera ZrO2

Techniques
* Slip casting
* Copy milling
* Two piece
* Heat pressure
- Zirconia ceramics
Ceramics for use in dental implants
Ceramics for use as orthodontic brackets.
Ceramics inserts.
Ceromers
Polymeric rigid inorganic matrix material
(PRIMM)

Tooth preparations
 All ceramic
 Metal fused to ceramic
 Veneers
Summary & Conclusions

Ceramics are thought to be the first material ever made by
man. Although, routine use of ceramics in restorative
dentistry is a recent phenomen, the desire for a durable and
esthetic material is ancient
However, the mechanical properties and physical
properties and the manufacturing technique of conventional
dental ceramics have revealed certain clinical short comings
i.e. extensive brittleness, crack propagation, low tensile
strength, fracture of the restorations, wear of antagonists and
sintering shrinkage. These shortcomings among other factors
have limited the indications for dental ceramics

In an attempt to meet the requirements of dental materials
and improve their strength toughness, several new ceramic
materials and techniques have been developed during past
few decades
Dentists today can choose from a variety of ceramic
materials in dentistry, hence should be familiar with the
range of metal ceramic and all ceramic materials available
for fabrication of ceramic restorations

What are Ceramics ?
Ceramic is an inorganic compound with non-metallic
properties typically composed of metallic (or semi metallic)
and non-metallic elements (example AI2O3, CaO)
- Kenneth J. Anusavice
Dental ceramic is an inorganic compound with non-
metallic properties typically consisting of oxygen and one or
more metallic or semi metallic elements (e.g.. Al, Ca, Li,
Mg, K, Si, Na, Sn, Ti and Zr) that is formulated to produce
the whole or part of a ceramic based dental prosthesis

Ceramic may be defined as a compound of metallic
and non metallic elements, the formation of which requires
high temperature
Dental ceramics contain a glassy matrix reinforced by
various dispersed phases consisting of crystalline structures,
such as leucite, alumina and mica
Porcelain is a specific type of ceramic characterized
by it being white and transparent
- A. Peutzfeldt, 2001
Ceramic is an earthy material usually of a silicate
nature, and may be defined as a combination of one or more
metals with a non metallic element usually O2
- Gilman 1987

During the stone age, more than 10,000 years ago,
ceramics were important materials and have retained
importance in human societies ever since
700 BC - the Etruscans made teeth of ivory and bone
that were held in place by a gold framework
Animal bone and ivory from hippotamus or element
were used for many years thereafter
Later human teeth sold by the poor and teeth obtained
from dead were used
History

1728 - Pierre Fauchard, French Dentist first proposed the use of
porcelain in dentistry
1774 - First porcelain tooth material patented by a French
dentist – de Chemant in collaboration with a French
Pharmacist – Duchateau
1789 - Fused porcelain was introduced for manufacture of teeth
1817 - Introduction of porcelain teeth to the United States by a
French Dentist, Planteau
1822 - Development of baking process in Philadelphia by Peale
1825 - Commercial production of these teeth began by Stockton

1839 - Invention of Vulcanized rubber allowed porcelain
denture teeth to be used effectively in a denture base
1870 - Dr. CH Land developed the first all porcelain jacket
crown using platinum foil matrix technique
1900 - Brewster introduced porcelain inlay for clinical use
1903 - Introduction of one of the first ceramic crowns to
dentistry by Dr. Charles Land
1930 - Lost wax technique or Taggard’s method (1907) of
forming 3 dimensional glass particles have been
developed by Fredrick Gardner

 Formulations of feldspathic porcelain that allowed systemic
control of the sintering & thermal expansion co-efficient
 Components that could be used to produce alloys that bonded
chemically to and were thermally compatible with feldspathic
porcelain
- Weinstein and Weinstein
(1962)
1963 - Development of 1st commercial porcelain by Vita
Zahnfabric
1965 - Significant improvement in the fracture resistance of
porcelain by McLean and Hughes

1976 - McLean & Sced developed the platinum bonded
alumina crown
1980 - Pressable glass ceramic (IPS empress) containing
34 vo1% leucite, and Zr ceramics introduced
1983 - First dental CAD/CAM milled and installed in a mouth
1984 - Dicor developed by Adair and Grossman
1986 -1st generation CEREC 1 (Siemens CAD CAM)
1989 - Concept of all ceramic post and core introduced

Late 1990’s - IPS empress 2 a second generation pressable
ceramic made from Lithium – disilicate
framework with a apatite layered ceramic
Early 1992’s - Celay copy milling system commercially
available
1994 - 2nd generation CEREC 2 CAD/CAM
1999 - IPS SIGN a feldspar free fluorapatite glass ceramic
system for use in metal ceramic

Larger oxygen atoms serves as a matrix with smaller metal atoms (Si)
tucked into spaces between oxygen. The atomic bonds in a ceramic
crystal have both a covalent and ionic character. These strong bonds are
responsible for greater stability of ceramics and impart useful properties
such as hardness, high modulus of elasticity. On the other hand, nature of
this bonding make them brittle.
StructureStructure

Composition

SILICA (Quartz as flint)
• Filler
• Strengthening agent
• Provides high strength frame work for other ingredients during firing
• Helps to maintain the form (Shape) of a free standing object during
firing
KAOLIN (WHITE CHINA CLAY)
• Increases the mouldability of plaster porcelain
• Acts as a binder to helps in maintaining the shape of the unfired
porcelain during firing
• At high temperature it fuses and reacts with other ingredients to form the
glassy matrix
Drawback
Opaqueness

Feldspars
Types :
•Albete (Soda feldspar)
- Decrease Fusion Temperature
•Orthoclase (Potash feldspar)
- Increase Viscosity of glass.
Role :
•Glassy phase formation
•Leucite formation

Leucite
Potassium silicate mineral with a large co-efficient of
thermal expansion
Feldspar crystals Glass and Leucite
Special heat treatment
Functions:
• increases coefficient of thermal expansion
• increases hardness and fusion temperature
• increases abrasive effect & strength

Glass formers
Oxides of titanium, Zn, lead and aluminum can all take
part in the formation of the glass network and produce stiff
network structures. However for dental purposes only two glass
forming oxides. Silicone & boron oxides are used to form the
principle network. During cooling, molten glass solidifies with a
liquid structure instead of a crystalline structure - Vitrification
Devitrification - however, a small amount of
crystallization always occurs during glass formation, although
the rate of crystal growth is low. When the glass begins to
crystallize, the process is called devitirification

Glass modifiers (flux):
Elements that interfere with the integrity of the SiO2
(glass) network and alter their 3 dimensional state.
Functions:
To decrease softening point.
To decrease viscosity
Higher concentration of glass modifiers
- Decrease chemical durability (resistance to attack by
water, acids and alkalis)
- Devitrification due to disruption of too many tetrahedral
networks

Boron oxide fluxes
Powerful flux (Glass modifies)
Can also act as a glass former & forms its own glass
network- Boron glasses
Water
• Important glass modifier
• H3O+ (Hydronium ion) replace Na+ or other metal ions in
a ceramic
• Slow crack growth of ceramic exposed to tensile stresses
and stored in moist environment
• Occasional long term failure

Colouring agents
Pigmenting or coloring oxides are added to obtain various
shades needed to stimulate natural teeth
Different coloring pigments used in dental porcelain
* Ferric oxides Grey
* Chromium oxide, Ca oxide Green
* Cobalt salts Blue
* Ferric oxides, Ni Oxide Brown
* Titanium oxide Yellowish brown
* Mn oxide Lavender
* Chromium – Tin, Cr-alumina Pink
* Indium Yellow/Ivory

Opacifying agents
Consists of metal oxide ground to a very fine
particle size to prevent speckled appearance of
porcelain
Cerium oxide
Ti oxide
Sn oxide
ZrO2

Stains
Stains are generally low fusing colored porcelains used to
imitate markings like enamel crack lines, calcification spots,
fluoresced areas etc.
More concentrated than color modifiers.
These are also called as surface colorants or characterization
porcelain.
Stains in finely powdered form are mixed with H2O or glycerin
Wet mix is applied, with brush either on to the surface of
porcelain before glazing or built into porcelain (internal staining)

Glazes
Glazes are low fusing uncolored glass powders that are
applied on the surface of a porcelain restoration & fired at a
maturing temperature lower than that of the restoration to
produce a transparent glossy layer on the surface
Purpose of glazing :
To seal the open pores on the surface of a porcelain
To impart an impervious smooth surface and develop greater
translucency in the porcelain restorations

Self glaze
After all the constituents of the porcelain frit have
completely melted to form a single phase glass, the
porcelain is further heated to reach glazing point at which
the surface becomes plastic & flows to form a shiny
continuous surface
Add on porcelain
Generally made from minerals similar to that of
glaze porcelain except for the addition of less finely
ground powder of opacifying and coloring pigment

 External glaze is applied on the surface
 Uncolored glasses whose firing temperature have been
lowered by addition of glass modifiers
 Thermal expansion lower than ceramic body to which it is
applied
 This placed the glazed layer under compression and
hence crazing or peeling of the surface is avoided

Disadvantages
Low chemical durability
Difficult to apply evenly
Impossible to attain a detailed surface
characterized
Used sparingly for repairs, addition to simple correction
to tooth contour or contact points.

Fluorescent agents
 Uranium salts
 Cerium oxide
 Samcarium
 Spinel (magnesia alumina compounds)
 Newer porcelain material – luminaries

MANUFACTURE AND DISPENSING
Manufacture
Ceramic raw materials mix together in a refractory
crucible and heated to high temperatures
Water of crystallization is lost, flux reacts with grains of
silica, kaolin and feldspar and partly combines them
together
Feldspar undergoes decomposition to form a glass and a
crystalline materials known as leucite

Molten glass begins to dissolve the kaolin and quartz
Continuous heating results in total dissolution and forms a
homogeneous glass. Fused mass is quenched in water
Frit is formed
It is ground to fine powder and can be used for fabrications
of porcelain restorations
When refired, particles form a very viscous liquid, shrink
during firing

Dispensing
 Fine ceramic powder of different shades of enamel
dentine core / opaque.
 Special liquid / distilled water – vehicle / medium on
ceramic powder / binder.
 Stains and colour modifiers
 Glazes and add on porcelain.

Classification
Based on its use or indications
* Crowns
* Veneers
* Post and cores
* FPD’s
* Stain ceramic
* Glaze ceramic
- K J. Anusavice

Based on composition
* Pure Alumina
* Pure Zirconia
* SiO2 glass
* Leucite based glass
ceramic
* Lithia based glass
ceramic
Processing methods
* Sintering
* Partial sintering
* Glass infiltration
* CAD – CAM
* Copy milling

Based on Firing temperature
* Low fusing
* Medium fusing
* High fusing
Based on Translucency
• Opaque
• Translucent

According toAccording to Structure
Non-crystalline ceramics
– Example : Feldspathic porcelain
– Composite of crystalline minerals (Feldspar, SiO2 ,and A12O3) in an
amorphous (non-crystalline) matrix of glass (Vitreous phase)
High expansion
Low expansion
Crystalline ceramics
– Example: Aluminous porcelain
– Ceramics reinforced with crystalline inclusion such as A12O3 into
the glass matrix to form crystal glass components

According to composition
• Feldspathic porcelain
• Leucite reinforced porcelain
• Aluminum porcelain
• Alumina
• Glass infiltrated alumina
• Glass infiltrated spinel
• Glass infiltrated zirconia
• Glass ceramics.

According to use
•Denture teeth
•Metal ceramics
•Veneers
•Inlays
•Crowns
•Anterior bridges
•Posterior bridges
According to processing methods
•Sintering
•Casting
•Machining

According to the firing temperatures
• High fusing – more than 1300°C
• Medium fusing - 1101 – 1300°C
• Low fusing - 850 – 1100°C
• Ultra low fusing – less than 850°C

According to method of fabrication
- Rosenblum and Alan Schulman ,1997
1. Conventional Powder and slurry ceramics
 Alumina reinforced porcelain : Hi-ceram
 Magnesia reinforced porcelain : Magnesia cores.
 Leucite reinforced (high strength) : Optec HSP.
 Zirconia whisker – fibre reinforced : Mirage II.
 Low fusing ceramics
Hydrothermal LFC :Duceram
Finesse

2. Castable ceramics
 Fluoromicas –Dicor
 Apatite based glass ceramic -Cerapearl
 Other glass ceramic -Lithia based
- CaPO4 based

3. Machinable ceramics
Analogous systems
1. Copy milling / grinding technique
Mechanical –Celay
Automatic –ceramatic II
2.Erosive techniques
Sono-erosion
Erosonic
Spark erosion -Procera
Digital systems (CAD/CAM)
1. Direct -Cerec 1 and Cerec 2
2. Indirect -Cicero, Denti CAD, Automill

4. Pressable ceramics
By pressure molding and sintering
1. Shrink free alumina reinforced ceramic
Cerestore/Alceram
2. Leucite reinforced ceramic
IPS empress
IPS empress 2
Optec OPC
5.Infiltrated ceramics
Alumina based - Inceram alumina
Spinel based - Inceram spinel
Zirconia based - Inceram zirconia

.
According to application
Core porcelain
Body porcelain
Enamel porcelain
According to method of firing
Air fired
Vacuum fired
According to use
A. Metal ceramic systems
Cast metal ceramics –Vita Metal Keranuk
Non-cast metal systems (foil crown system)
B. All ceramic systems

 Dental porcelain restorations are made by mixing
ceramic powder of selected shades with distilled water or
a special liquid to form a plastic mass
 This is condensed either directly on a refractory die or a
matrix shaped into the desired form, then fused in a
furnace by firing to develop a translucent tooth like
material (Fused porcelain)

Various methods of fabricating ceramic restorations
 Condensing and sintering
 Pressure moulding and sintering
 Casting and ceramming
 Slip casting, sintering and glass infiltration
 Milling by mechanical and digital systems
However, fabrication of a conventional porcelain restoration is
basically composed of the following stages:
Condensation - Sintering – Glazing – Cooling

Instruments
 Fine bladed spatulas & carving point
 Fine hair brush of varying thickness

Condensation (Compaction)
The process of packing the particles together and
removing the liquid binder is known as condensation
•Vibration method
•Spatulation method
•Dry brush technique
•Whipping method

Binder
 Helps to hold the particles together as the porcelain
materials is extensively fragile in the green state
 Distilled water – commonly used for dental / enamel
porcelain
 Propylene glycol – for alumina core build up
 Alcohol or formaldehyde based - for opaque core
build up liquids
 Proprietary modeling fluids
 Paint on liquids for stain application

Mixing
Dry porcelain powder is mixed with the binder on a
glass slab using bone or nylon spatula (or glass mixing
rod) into a thick creamy consistency which can be carried
in small increments with an instrument or brush

Additional equipment - Ceramosonic condenser
Used for uniform condensation without distortion
Provides fine continuous vibration at a frequency
of 20,000 – 28,000 Hz
Promote good packing density

Sintering or firing
Is defined as a process of heating closely packed
particles to achieve interparticle bonding and sufficient
diffusion to decrease the surface area or increase
density of the structure. The partial fusion or compaction
of glass is often referred to as sintering

During firing, the following changes are seen in the
porcelain
 Loss of water
 Firing shrinkage - 32 –37% for low fusing
28 – 34% for high fusing
 Glazing - 955 – 1065°C
After the mass has been fired, it is cooled very slowly
because rapid cooling might results in surface cracking
and crazing

BEFORE FIRING AFTER FIRING
After firing, grain boundaries fuse to form prismatic structure

Different media can be employed for firing like
1. Air
2. Vacuum
3. Diffusible gas
- He, H2 or steam

STAGES OFSTAGES OF
MATURITYMATURITY
Low bisqueLow bisque MediumMedium
bisquebisque
High bisqueHigh bisque
CharacteristicCharacteristic
featurefeature
Grains start to soften &Grains start to soften &
coalesce at contactcoalesce at contact
pointspoints
Flow of glass grainsFlow of glass grains
increase & residualincrease & residual
entrapped airentrapped air
becomes spherebecomes sphere
shapedshaped
Firing shrinkageFiring shrinkage
complete & anycomplete & any
correction bycorrection by
grinding prior togrinding prior to
glazing.glazing.
ParticleParticle
cohesioncohesion
IncompleteIncomplete ConsiderableConsiderable CompleteComplete
PorosityPorosity Highly porousHighly porous Decreased butDecreased but
porousporous
Slight/absentSlight/absent
ShrinkageShrinkage MinimalMinimal Majority/definiteMajority/definite HighHigh
Surface textureSurface texture PorousPorous Still porous &matteStill porous &matte
surfacesurface
Smooth surfaceSmooth surface
Color &Color &
translucencytranslucency
OpaqueOpaque Less opaque &Less opaque &
color developedcolor developed
Color &Color &
translucencytranslucency
developeddeveloped

Glazing
Produces a smooth, shiny and impervious outer layer
Decrease crack propagation
Avoid loss of surface detail
Controls the pyroplasticity
Add on glazing
A low fusing transparent glass may be used as a glaze over
the completed body of the porcelain at a relatively low
temperature is sufficient to fuse the glaze
Self glazing
Further stage of advancement in vitrification from the bisque
finish stage, done by increasing the time of high bisque
maturation. www.indiandentalacademy.comwww.indiandentalacademy.com

Internal staining and application of characterized
stains
Advantages
Permanent effect
Can produce life like results
Disadvantages
Must be completely removed if the color or
characterization is unsuitable

Cooling
Being poor conductors of heat and brittle in nature,
whenever, porcelain restorations are heated or cooled the
process must be carried out slowly.
Rapid cooling or sudden changes in temperature after
firing of porcelain would result in cracking or fracture of
glass and loss of strength because of development of
tensile stresses.

Bonding of ceramic restorations to the tooth
Mechanical
Chemical
Mechanical - Adherence relies on the degree of
roughness of the bonded surfaces and may
be obtained with any cement
Chemical - Adherence by use of a resin cement by acid
etch technique
Perelmuter & Montagnon- 1981
Silanization of etched ceramic surface acts by giving
a chemical component to the mechanical adherence
provided by the etching.

In Ceram - Sandblasting in combination with adhesive
cement or Rotatec treatment - best surface
treatment
(Kern and Thompson 1995).
Silane is a bifunctional molecule that reacts
with the ceramic surface through one end of the molecule,
while the other end is a methacrylate group capable of co-
polymerizing with the monomers of the resin cement
It has been found that a heat treatment of the silanated
ceramic surface to about 100°C gave significant increase in
bond strength
(Roulet, Soderholm and Longnate 1995)

Uses
• For bonding indirect porcelain restorations
• For intra oral repair of porcelain surface

Properties of porcelain
Desirable properties
 Good esthetic qualities
 High hardness
 High compressive strength - 50,000 psi
 Good chemical durability
 Excellent biocompatibility
Principle deficiencies
Brittleness
Low fracture toughness
 Low tensile strength – 5000 psi
 Shear strength - 16000 psi
Elastic modulus - 10x106
psi
KHN - 460
Linear coefficient of thermal expansion 12x106
/°Cwww.indiandentalacademy.comwww.indiandentalacademy.com

Thermal conductivity - 0.00500
C/cm
Diffusivity - 0.64mm/sec
Specific gravity - 2.2 – 2.3
Linear shrinkage
High fusing – 11.9%
Low fusing – 14.0%
Refractive Index – 1.52 –1.54

Methods for strengthening ceramics
K.J. Anusavice ,1996
Methods of strengthening brittle materials
Development of residual compressive stresses
Ion exchange (Chemical tempering)
Thermal tempering
Thermal compatibility

Interruption of crack propagation
• Dispersion of crystalline phase
• Transformation toughening
Methods of designing components to minimize
stress concentration and tensile stresses
• Minimizing tensile stresses
• Reducing stress raisers

Development of residual compressive stresses.
Main object is that the residual stresses must be first be
negated by developing tensile stresses before any net
tensile stress develops
Ion exchange
 Sometimes called as chemical tempering
 More sophisticated and effective method

Ion exchange in crown Ion exchange in potassium
nitrate
Disadvantages
 Depth of compressive zone is less than 10 um
 Strengthening effect could be lost if the porcelain surface
glass ceramic surface is ground, worn or eroded by long term

Thermal tempering
Creates residual compressive stresses through rapid cooling
(quenching) the surface of the object while it is still hot in the softened
(molten state)
Rapid cooling
Skin of rigid glass surrounding a soft (molten) core
Solidifies and shrink
Creates residual tensile stress in the core and residual
compressive stress within the outer surface

Uses
To strengthen glasses used for automobile windows and
windshield, shielding glass doors and diving masks
For dental applications, it is more effective to quench hot
glass phase ceramics in silicon or other special liquids
rather than using air fets that may not uniformly cool the
surface

Thermal compatibility
Ideally, porcelain should be under slight compression
in the final restoration, hence for metal ceramic restorations,
the metal and porcelain should have a slight mismatch in
their thermal contraction coefficients
Since the metal thermal contraction co-efficient is slightly
larger, the metal contracts slightly more than the porcelain
on cooling
This mismatch leaves the porcelain in residual compression
and provides additional strength for the restoration

Interruption of Crack propagation
Methods
• Dispersion of a crystalline phase
• Transformation toughening

Dispersion strengthening
Definition
Method of strengthening glasses and ceramics by reinforcing
them with a dispersed phase of a different material that is capable of
hindering a crack from propagating through the material. This process is
referred to as dispersion strengthening
When a tough, crystalline material such as alumina (AI2O3) is
added to a glass, the glass is toughened and strengthened because the
crack cannot pass through the alumina particles as easily as it can pass
through the glass matrix
This technique used in the development of porcelain jacket crowns

Draw backs
 Expensive equipment and materials
 High laboratory fees
 Not strong enough for FPD
 Technique sensitivity
 High fracture / failure rates

Transformation toughening
When small, tough crystals are homogenously
distributed in a glass, the ceramic structure is toughened
and strengthened because cracks cannot penetrate the
fine particles as easily as they can penetrate the glass
Alumina - Procera all ceram
In-ceram alumina
Leucite - Optec HSP, IPS Empress, OPC).
Tetrasilicic fluoramica - Dicor, Dicor MGC
Lithia disilicate - OPC 3G, IPS Empress 2
Magnesia alumina spinel - In Ceram spinel

Zircornia crystals - cercon & lava
Undergo transformation toughening that involves a transformation
of ZrO2 from tetragonal crystal phase to a monoclinic phase at the tips of
cracks that are regions of tensile stress
Tetragonal - volume increase - monoclinic
This transformation can be prevented with certain addition such
as 3mol% yttrium oxide (Yttria or Y2O3). This material is designated as
ZrO2.TZP (Tetragonal zirconia polycrystals)

Methods of designing components to minimize stress
concentrations and tensile stresses
Minimizing tensile stress
In porcelain jacket crowns (PJC) - In posterior teeth - occlusal forces
cause concentration of large stresses near the interior surface of the crown
Anterior teeth -Great amount of vertical overlap (overbite) with only
moderate amount of horizontal overlap.
In metal ceramic crowns (MCC’s)
The stiff, metal coping minimizes flexure of the porcelain structure of the
crown that is associated with tensile stresseswww.indiandentalacademy.comwww.indiandentalacademy.com

One way to reduce tensile stresses on the cemental
surface in the occlusal regions of ceramic inlay or crown is
to use the maximum occlusal thickness possible

Reducing stress raisers
Stress raisers are discontinuities in ceramic structures
and in other brittle materials that cause stress concentration

In porcelain Jacket Crowns (PJC’s)
•Creases or folds in the platinum foil substrate that become
embedded in the porcelain and leave behind notches (Stress
raisers)
• Sharp line angles in the tooth preparation
• Large change in porcelain thickness
• Small particles of porcelain along the internal porcelain margin
of a crown
In metal ceramic crowns (MCC’s)
• Stray porcelain particle fused within the internal porcelain
margin
• Occlusion not adjusted properly
• Contact points

The mechanisms that can lead to toughened or
strengthened ceramics can be categorized into 3 types
•Crack tip interactions
•Crack tip shielding
•Crack bridging
-Seghi / Sorensen -1995
Each of the mechanisms involves the incorporation of a second
phase of heat generated crystal production

Crack tip interactions
• Obstacles in the micro structure generally
in second phase act to deflect crack out of
the crack plane
• Reduction of the force being exerted on the
crack
Crack tip shielding
Occurs when events are triggered by high
stresses in the crack tip region that act to reduce these
high stresses

Crack tip bridging
Occurs when second phase acts as a ligament to
make it more difficult for the crack faces to open
• Hi- ceram (Core)
• Vitadur N (Core)
• Mirage II (Fiber)

• Enameling of metals
• Dispersion strengthening
Aluminum porcelain
Slip casting alumina (InCeram)
Non Shrink ceramics (Cerestore)
• Crystallization of glasses – Dicor, Dicor plus
• Chemical toughening – Ion exchange
• Bonding to foils – platinum foil
• Foil crown systems (Renianance)
- John W. McLean 1991

Enameling of metals
Porcelain is fused directly to metal coping serving as a
metallic substrate
A strong bond is achieved between the porcelain and metal
The porcelain veneer reinforced by the cast metal
Substructure is less likely to succumb to fractures under
tensile stresses

Crystallization of glasses
Controlled crystallization of glasses was developed by
Stookey to increase the strength and the thermal shock
resistance
Glass was made to crystallize by heating to a suitable
temperature with the crystal seed or nuclei present
Bonding to foils
Foil crown systems where a thin metallic foil is used
as matrix / sub structure to strengthen porcelain

Esthetic properties of Dental Ceramics
•Dental porcelain are pigmented by the inclusion of
oxides to provide desired shade
•Specimens of each shade (Collectively called a shade
guide) are provided for the dentist, who in turn attempts
to match the tooth color as nearly as possible
Disadvantages
• Shade guides tabs are much thicker
• More translucent
• Necks of the shade tabs are made from a deeper hue

Degradability
Mechanical forces
Chemical attack
•1.23% APF or 8% stannous fluoride
•Dissolution of glass phase from ceramic surface
•Surface roughness
•Staining & plaque accumulation

Feldspathic porcelain
SiO2 - 52-62 wt %
A12O3 - 11 –16 wt %
K2O - 9–11 wt %
Na2O - 5 – 7 wt%
- Certain additives, including LiO and B2O3.
- Contain a glass matrix and one or more crystal phases.
- No controlled nucleation and crystal formation and growth
- There are four types of veneering ceramics
• Low fusing ceramics
• Ultra low fusing ceramics (porcelain and glasses).
• Stains www.indiandentalacademy.comwww.indiandentalacademy.com

Types of feld pathic porcelain
Non reinforced feldspathic porcelain example
Vit. VKM 68 (Vita)
Excello (Ceramco Int)
Modification (Low sodium)
Vita VMK 68-N (Vita)
Will Ceram (Williams Dental Co. NJ)

Reinforced feldspathic porcelain
Leucite reinforced
• Cerinate (Den – Mat Corp CA)
• Corum (Ivoclar vivadent)
• G. Cera (GC Int. Scottsdale)
Fibre reinforced
• Mirage II
Also sub divided into
• High - expansion porcelain - veneering metal and
magnesia core ceramics.
• Low - expansion porcelain -veneering other core ceramics

According to their firing temperature by
High fusing 1300°C
Medium 1101 – 1300°C
Low fusing 850 – 1100°C
Ultra low fusing 850°C
- Anusavice (1996)

High fusing porcelain
High feldspar 70-90%
Low kaolin 1-10%
Quartz 11-18%
Manufacture-
The raw minerals were mixed with small quantities of
starch, vaseline & water
 Mix is then compressed in a mold & heated to gelatinize
the organic components
Pieces were then extracted from the cooled mold, dried &
fired at temperature approaching 1316°Cwww.indiandentalacademy.comwww.indiandentalacademy.com

Uses
Used for PJC & denture teeth

Medium fusing porcelains
Repeatedly fired to reduce the fusion temperature &
finely ground
Manufacture-
By fritting process where all the constituents are
fused, quenched, & ground back to an extremely fine
powder
Uses
For PJC & inlayswww.indiandentalacademy.comwww.indiandentalacademy.com

Low fusing porcelains
Characteristic features
 Low fusion temperature
 Chemically similar but micro structurally different from
the high fusing porcelains
 Higher proportion of glass modifiers
Uses
 In Ceramo-metal restorations
 Alter the color tint & degree opacity to produce tooth
like shades

Physical properties
• Compatibility with variety of metals
•Low abrasive wear against natural enamel
• Highly polishable in the mouth
Examples
• Golden Gate system
• Ducera gold
• Duceram LFC
• Procera – Al ceram
• Vita omega 900
• Mirage P www.indiandentalacademy.comwww.indiandentalacademy.com

Golden Gate system
Golden yellow alloy with high gold content coordinate with
a hydrothermal low fusing ceramic
• The development of Golden Gate system was based on
the idea of being able to veneer a universal low fusing alloy
• This development further led to the development of leucite
containing porcelain- Duceragold

Duceragold
• Leucite containing hydrothermal glass ceramic system with
fusion temperature of approx-800°C
•The leucite crystals are highly dispersed & are responsible
for the required high resistance to hydrolysis, chemical
attack without the addition of fluxes &high flexural strength

Degunorm
Type 4 high gold (deep yellow)
Gold 73%
Platinum 9%
Silver 9.2%
Palladium free,extra hard, low melting range
(900-990°C)

IPS SIGN d
(Ivoclar)
• Feldspar free fluorapatite glass ceramic system for use with
metal
• Fluorapatite glass are intended to allow natural teeth to be
imitated very closely
• Metal ceramic alloy- a collection of 5 different ceramic alloys
were developed specifically for use with IPS SIGN- high gold,
gold based, Pd based, Pd-Ag & Co-Cr based alloys

Metal ceramic systems
Ceramic jacket crowns (PJC’s) using high fusing
feldspathic porcelain had been in widespread use since the
beginning of the 20th century
However its relatively low strength prompted McLean to
develop an alumina reinforced porcelain core materials. But it
still lacked tensile and shear strength for use as an allceramic
restorative materials

Others names
•Ceramic crown
•Porcelain veneer crown (PVC)
•Porcelain fused to gold (PFG)
•Porcelain fused to metal (PFM)
Composed of
•A metal casting or coping which fits over the
tooth preparation
•A ceramic that is fused to the coping

Fabrication
• Metal substructure waxed, cast, finished and heat treated
•A thin layer of opaque porcelain fused to metal sub structure to
initiate the porcelain metal bond and mask metallic color
•Dentin and enamel porcelain (Veneer porcelains) fused, shaped
and fired

Classification
According to noble metal content, metal ceramics are broadly
classified by the into 3 major categories
High Noble alloys.
• Gold – Platinum (Al-Pt-Pd) -Jelenko
• Gold – Palladium - silver
• Gold – Palladium : Olympia (Jelenko)
Noble alloys
• Palladium based alloys
• Palladium - silver -Jel star
Will ceram W-1
• Palladium - gold alloys
Pd – Au – Ga : Olympia II
Pd – Au – Ag : Jeneric

High Pd alloys
• Pd – Cu
• Pd – Cu – Ga – Au ( Liberty (Jelenko)
• Pd – Cu – Ga (Williams)
• Pd – Co (Aderes)
• Pd – Co – Ga (Jeneric)
• Pd – Ga
Base metal alloys
Nickel based
Ni – Cr
Ni – Cr – Be
Cobalt based
Co -Cr - Fe- Cr
Titanium based
Ti, Ti 6Al – 4Vwww.indiandentalacademy.comwww.indiandentalacademy.com

Generally classified into two general categories
Alloys – Noble metal alloys
• Gold – Platinum
• Gold – Platinum - silver
• Gold - palladium
• Palladium - silver
• High palladium
System base metal alloys
Nickel – Chromium
Cobalt – Chromium
-Anusavice 1996www.indiandentalacademy.comwww.indiandentalacademy.com

HIGH NOBLE METAL ALLOYS
Metal ceramic alloys containing more than 4wt% gold &
atleast 60wt% of noble metals( gold, platinum, palladium/or
other noble metals)
• Gold- platinum-palladium
• Gold- platinum-silver
• Gold-palladium
Au- promotes the handling characteristics of the alloy
Pt-hardens the gold
Pa- lowers the coefficient of thermal expansionwww.indiandentalacademy.comwww.indiandentalacademy.com

Au-Pt-Pd
• Au-85-90%
•Pt- 5-10%
•Pd- 5-7%
•Fe- 0-1%
•In- 0-1%
•Sn-0-1%
Disadvantage
• Susceptible to sag formation

Au-Pd-Ag
• Au-50%
• Ag-2%
• Pd-30%
• In/Sn- 8%
Advantage-
More economical, harder & stronger
Disadvantage-
Presence of silver increases the coefficient of
thermal expansion and tendency to discolor (greening)

Au-Pd
• Au- 44-55%
• Pd- 35-45%
Advantage-
No greening of porcelain
Disadvantage-
Very expensive &lack of silver decreases the coefficent
of thermal contraction

NOBLE ALLOYS
Pd-Ag
• Pd- 53-61%
• Ag-28-40%
• Sn/In or both increases hardness & promote the formation
of surface oxides
Disadvantage-
Greening of the porcelain

Pd-Au alloys
Pd-Au-Ga (olympia jelenko)
Pd-57%
Au-35%
Ga-5%

HIGH PALLADIUM ALLOYS
 Pd-Cu
Pd-74-80%
Cu- 9-15%
 Pd-Cu-Ga-Au
 Pd-Cu-Ga
Disadvantage-
Porcelain discoloration
Susceptible to creep deformation
Technique sensitivewww.indiandentalacademy.comwww.indiandentalacademy.com

Pd-Co
• Pd-78-88%
• Co- 4-10%
• Ga-8%
Advantage
Sag resistant
Disadvantage
Discoloration due to to presence of cobalt

Pd-Ga
 Pd-75-80%
Ga-5-10%
 Ag-8%
Advantages
 Slightly lighter colored oxides than Pd-Cu/Pd-Co
 Thermally compatible with low expansion porcelain

BASE METAL ALLOYS
Nickel based
Ni-Cr
Ni- 61-80%
Cr-11-27%
Mo-2-5%
ex- Talladium, Litecast
Ni-Cr-Be
Be-8% to decrease the fusion temperature
Disadvantage-
Potential toxicity of beryllium
Allergic potential of nickelwww.indiandentalacademy.comwww.indiandentalacademy.com

Cobalt based
Co-Cr
Co-53-67%
Cr-25-32%
Mo-2-6%
ex- genesis2
Biocast
Dent O Bond
Neobond 2
Fe-Cr
ex- dentilum
C&B www.indiandentalacademy.comwww.indiandentalacademy.com

Titanium based
Commercially pure Ti (CpTi) is an alpha alloy of titanium
containing minor amounts of O2 & N2
Ti-6Al-4V
• One of the super elastic alloys
• Exhibit excellent elongation at temperature 800-900°C
Advantages
• Excellent biocompatibility
• High corrosion resistant
• Low density www.indiandentalacademy.comwww.indiandentalacademy.com

Disadvantage-
• Requires special handling characteristics
• Significant problems associated with casting, soldering &
bonding to porcelain
ex-
• Tycast
• Ticeram
• Duceratin

Recent developments in porcelains used for metal
ceramic restorations
• Opalescence
• Specialized internal staining techniques
• Greening resistant porcelains
• Porcelain shoulder margins
Porcelain materials for metal ceramic restorations must meet the
requirements of ADA specification No 39 for flexural strength,
chemical stability and porosity of bonded restorations

SiO2 – 69.4% (Glass formers)
B2O3 – 7.4% (Glass formers)
CaO – 1.9% (Fluxes)
K2O – 8. 3% (Fluxes)
Na2O – 4.8% (fluxes)
A12O3 – 8% (Intermediates)
- In 1974 – Mc Lean
Feldspar is not present in final processed porcelain and
the increase in thermal expansion of porcelain occurs
due to crystallization of leucite, hence these high
expansion porcelain are also called leucite porcelains

Metal ceramic restorations kit supplied by the
manufacturers mainly includes
• Opaque porcelains
• Body porcelains
• Incisal porcelains
• Stains
• Glazes

Opaque porcelain
High expansion feldspathic glasses with fusion
temperature lower than the intended substrate and contain
large amounts of opacifiers such as TiO2 and ZrO3
• Fused directly to the metal coping
• 1st ceramic coat to a thickness of 0.3 – 0.4 mm
• Fusion temperature – 1760° – 1850°F slightly higher
than that of overlying body porcelain
Functions
•Mask the colour of the alloy (metal susbtrate)
•Initiate the porcelain to metal bondwww.indiandentalacademy.comwww.indiandentalacademy.com

Body porcelain
Low fusing feldspathic glasses with high color saturation
due to various concentrations of colorant oxides
Uses
• For main build up of body and gingival areas of crown
• Build up tooth contour
• Develop esthetics by diffusing and softening the opaque
color
Types
• Gingival / dentin shades – contain small amounts of
colorants
• Incisal porcelain - glasses with virtually no colorant oxides

Incisal porcelain
Use –
To veneer the body porcelain and impart
translucency and incisal characteristics, hence
sometime referred to as enamel porcelain or
translucent porcelain

Stains and Glazes
Stains are color modifiers containing large amount of
colorants ranging across the color spectrum including white and
grey
Use
To impart superficial characterization or internal staining
of porcelain that can mimic the life like appearance of natural
teeth

Glazes
Low fusing uncolored glass powders, used to create a
glassy veneer free of surface porosities in a porcelain
restorations and place the surfaces under compression to
reduce crack propagation
* Fine grain –5 - 110 mm
* Coarse grain – up to 200 mm

Metal ceramic bonding
Chemical bonding by direct electron transfer
between oxygen of the glass and oxidizable metal
coping is generally responsible for metal porcelain
adherence in most systems
Methods of attaching porcelain to metal
• Molecular
• Mechanical
• Compressive bonding

Molecular bonding
2 possible mechanism
1. The metal surface oxide acts as a permanent component of
the bond like sandwiched structure
2. The metal oxide dissolves into the glass phase of the porcelain
and brings the porcelain into atomic contact with the metal
surface
Wetting of the metallic substrate by the glassy porcelain is thus
very effective in direct bonding of porcelain to metal
-McLean and Seed 1976

Surface oxides for porcelain bonding can be provided by
1. Introducing traces of base metals into precious metal
alloys, which on heating will produce thin oxide films
2. Direct oxide production via the constituents of the
alloys (base metal)
3 .Electro deposition of indium or tin on the noble metal
alloys

Mechanical bonding
Micro abrasion or surface roughness produced by
sandblasting can provide mechanical keying and increase
the surface area of porcelain attachment
-McLean and Sced 1976,Lugasy 1977
Compression bonding
By the process of thermal contraction when an alloy
with slightly higher co-efficient of thermal expansion than
porcelain is used, it causes the porcelain to contract
towards the coping when the restorations cools after firing

By atypical methods
Electro deposition
Other methods – the foil crown systems
– Captek system, Renaissance system, Ceptalec system
Electro deposition
• Improves wetting onto the metal
• Reduces the amount of porosity at the metal porcelain
interface
• Electrodeposited layer acts as barrier to inhibit diffusion of
atoms from the metal into the porcelain, within the normal
limits of porcelain firing cycles

Methods developed for bonding of metal and
ceramic surface using resin bonding materials
Surface conditioning methods
* Mechanical bonding
* Macro mechanical
* Micro mechanical
* Electrochemical etching
• Electrolytic tin plating
Chemical etching
*Chemical bonding
•Adhesive chemical bonding

Surface conditioning methods
Mechanical bonding
Direct technique –bonding to etched enamel surface
using a resin composite material
Indirect technique –bonding of perforated cast metal
splint to enamel with resin
Macro mechanical bonding
•One of the oldest method
•Cement locking into the metal which had perforated design
or mechanical beads

Micro mechanical bonding
• Involves sandblasting fine roughness increase the
bonding surface area, enhancing mechanical and
chemical bonding between resins and metals
• Long term durable bonding can be obtained with resin
composites that contain phosphate monomer
Electrochemical etching
• Most widely used
• Disadvantages – Difficulty in creating a properly etched
surface and that it did not work well with metal alloys

Electrolytic tin plating
• The metal surface is electrolytically coated with a thin layer
of tin oxide at 6 V
• The layer is placed on the freshly sandblasted metal
surface, which acts as the cathode, with a felt tipped oxide
moistened with a solution of opaque resin and tin surface is
then oxidized & air dried
• A second coating of tin is applied at 9V and the surface is
oxidized, washed with water and dried

• A special opaque resin is then applied before the resin
veneer is built up
• Tin oxides form crystals on the surfaces of the alloy,
making it easy for the resin to penetrate and produce
mechanical and chemical retention

Chemical etching
• Originally suggested by heredities in 1986
• Simple to use at chair side
• Etching pattern is shallow
• Restorations can be re-etched in case of failure
SR spectra link (Ivoclar)
Creates physiochemical bond between the resin and the
metal within silane coating
• It is a light cure adhesive resin based on methacrylic acid
which has 3 components
• Metal active
• Resin activewww.indiandentalacademy.comwww.indiandentalacademy.com

Silicoater classical
• Developed by Tiller et al 1984
• Used for bonding veneer resin to metal
•Silicon dioxide as intermediate layer promotes sufficient
bonding of the resin via silane bonding agent
Disadvantage
• Expensive

Silicoater MD (metal dotted)
Newer version of the silicoater classical technique
requiring a special oven that burns a chrome – endowing
silica layer onto the surface
Advantage : Avoids flame adjustment problems

Kevloc AC
System introduced in 1995 offers combination of chemical
and mechanical bonding
Rocatec system (ESPS)
Introduced in 1989 based on the principle of a tribochemical
application of a silica layer by means of sandblasting
Adhesive chemical bonding
Combines the advantages of chemical adhesive systems
and that of sandblasting -Panavia Ex and Panavia21
.

Advantages of metal ceramic restorations
• More resistance to fracture than traditional All-ceramic
crown
• Only dependable means of fabricating an esthetic FPD
when full coverage is required

Non Cast Metal ceramic systems
Introduced by Dr. Itzhak Shoher and Aaron Whiteman
Foil crown systems
Foil crown technology represents a novel approach
by which metal ceramic crowns can be produced in a
relatively short time without melting and casting the
metal
Types – Renaissance, Captalek, Sunrise, Flexbond
and Platideck

Reniassance crown
Originally developed by Shoher and Whiteman
Preformed laminated gold foil (approx. 0.05 mm thick)
Quter layer – 15 μ pure gold
Other layers – alloys of 85 % Au, 5% Pt, 5% Pd
Warm the colour of the crown and facilitate tooth color
Corrugations allow for some expansion and reburnishing,
according to the size of the tooth preparation

• Selection of proper sized form
• Initial adaptation
• Cutting the folds at the mid point.
• Folding pleats in same direction
• Burnishing the form for closer adaptation and trimming excess metal
• Die spacing using strips of plastic sheet
• Swaging
• Alloying
• Application of interfacial alloy
• Firing (at 1000°C) to produce a sintered alloy surfacewww.indiandentalacademy.comwww.indiandentalacademy.com

Method - The pleated foil is swaged with a swaging
instrument, burnished with a hand instrument on the die, and
then flame sintered to form, a rigid coping, with moderate
strength
• An interfacial alloy powder is applied and fired, the form is then
trimmed and veneered with porcelain (Condensation process)
and finally sintered

Captek system
• In this system bonding to porcelain is achieved by the
formation of an intermediate layer - capbond metal ceramic
binder (bonding agent) for captek foil crown system
• Two strips of highly malleable metal powder impregnated
with wax are adapted to a refractory die
•This first strip contains a gold, platinum and palladium alloy
and the second is impingement with all gold

Method
•The first strip is fired onto a refractory die at 1075°C for
11 mins producing a rigid porous layer
• Application and firing of the second strip is said to
result in capillary infiltration of the spongiform network
by the molten gold, resulting in metal alloy framework
with density similar to that of conventional casting
•A minimal thickness of opaque porcelain is required
prior to application of translucent porcelain

Disadvantages of foil crown systems
Although fabrication is relatively easier, results
comparing strengths have reported that the strength of
metal ceramic crowns was considerably higher than that of
foil based crowns (about 30 to 80% of the metal ceramic
system)

Galvanoceramic Restorations
• Used as an alternative to all ceramic restorations or ceramic
restorations with cast metal substructure
• Used with remarkable accuracy to create a thin, yellow gold
substructure of uniform thickness by a galvanic process
involving the electrolytic deposition of gold ions on a specially
prepared die
Advantages
• Thin (0.2mm) warm colored substrate
• Economical and simplified procedure
• Coping strength greater than foil crown systems
• Marginal adaptation of 15 to 20 um
• No porosity www.indiandentalacademy.comwww.indiandentalacademy.com

Disadvantages
• Uncertain bond quality of porcelain to metal
• Technique sensitivity
• Coping strength lower than conventional casting
• Unknown problems with creep

All ceramic systems
The term of “All ceramic” refers to any restorative
material composed excessively of ceramic, such as
feldspathic porcelain, glass ceramic, alumina core systems
and certain combination of these materials
-J. Esthetic Dent 1997,
9(2):86

Advantages
• Increased translucency
• Improved fluorescence
• Greater contribution of color from the underlying tooth
structure
• Inertness
• Biocompatibility
• Resistance to corrosion
• Low temperature / electrical conductivity

Disadvantages of Aluminum porcelains
• Required veneering with conventional feldspathic
porcelain to reproduce the contour and shade of a
natural tooth
• Firing shrinkage resulted in poor fit
• Extremely technique sensitive
• High rate of clinical fracture

Newer types of ceramic restorative
materials for All ceramic crowns, veneers
and inlays
•Variations of feldspathic porcelain Entirely different composition
•Optec HSP (Jencric/Pentron) Dicor (Dentsply L.D.Caulk)
• Inceram (Vivadent) Duceram LFC (Degussa Corp)
• Cerec (Vivadent)
• Celay (Vivadent)
• IPS empress (Ivoclar)
• Other pressable ceramic (Jeneric/Penton)

Lower incidence of clinical fracture
• Consist of stronger materials and involve better fabricating
techniques
• Can be etched and bonded to the underlying tooth structure
with the new dentin adhesives
• Clinicians now provide laboratory techniques with enough
room to create thicker and stronger restorations

Currently available all ceramics can be broadly
categorized according to their method of fabrication
• Conventional (powder slurry) ceramics
• Castable ceramics
• Machinable ceramics
• Pressable ceramics
• Infiltrated ceramics

Conventional Powder / Slurry ceramics
Alumina, reinforced porcelain (Aluminous porcelain)
•Hi ceram (Vivadent)
•Vitadur – N Core (Vivadent)
Magnesia –reinforced porcelain (magnesia core
ceramics)
• Leucite – Reinforced (non-pressed)
• Optec HSP (Jeneric/Pentron)
• Optec VP (Jeneric / Pentron)
• Fortress (Mirage Int)
• Cerinate (Den-mat Corp)

Low fusing ceramics
* Hydrothermal low fusing ceramics
Duceram LFC (Ducera)
* Finesse (Cerameo inc.)
Ziriconia whisker – fibre reinforced
• Mirage II (Myron Int. Kansas)

Alumina – reinforced Porcelain (Aluminous
porcelain)
Introduced by McLean and Hughes in 1965.
Alumina glass composites used in dental ceramic work have
been termed “Aluminous Porcelain”
- McLean and Hughes 1965

Based on the principle of dispersion strengthening
The glass used for incorporating alumina crystals
is generally
Borosilicate glass containing
• Silica – 62.0 – 65.0 wt %
• Alumina -17.0 – 20 wt %
• Potash - 6.5 – 7.7 wt %
• Soda -4.2 – 4.7 Wt. %
• Lime - 1.6 – 1.8 wt %
• Boric Oxide -6.7 – 7.3 wt %

Fabrication
• The objective of this technique is to improve the aesthetics by
a replacement of a thicker metal coping with a thin platinum
foil, thus allowing more room for porcelain
• Attachment of porcelain is secured by electroplating the
platinum foil with a thin layer of tin and then oxidizing in a
furnace - Tin oxide
• This tin oxide binds with porcelain
• This bonded foil will act as an inner skin on the fit surface to
reduce the sub surface porosity and formation of micro cracks

Properties
• Compressive strength -. 3,16,000 psi
• Transverse strength - 20,000 psi
• Shear strength - 21,000 psi
• Modulus of rupture - 15000 psi

Advantages
• Low coefficient expansion - 8 x 106
°C
• Improvement in strength if insufficient to bear high
stresses
• Fracture resistance is improved
• However it did decrease the amount of light
transmission, which diminished somewhat the esthetic
advantages of an All Ceramic restorations

Modifications
Hi Ceram
• Dispersion strengthened core crown fabricated utilizing
a refractory die
• Higher alumina content
• Crystalline phase increased in the volume 70% without
markedly worsening handling characteristic and opacity
• When fired directly on the refractory die - rough surface
finish - contributes to retention of restoration
• Flexural strength - 155 MPawww.indiandentalacademy.comwww.indiandentalacademy.com

IN CERAM

Magnesia – Reinforced Porcelain
• High expansion ceramics described by O’Brien in 1984 for
use of core material for metal ceramic veneer porcelain
• Made by fine dispersion of crystalline magnesia (40-60%)
• Magnesia crystals strengthen the glass matrix by both
dispersion strengthening and crystallization with the matrix
• Flexural strength - 131 MPa

Primary Advantages
• Increased co-efficient of thermal expansion improves its
compatibility with conventional feldspathic metal veneering
porcelain
• Improved strength and a high expansion property

Leucite reinforced porcelain
These porcelain contain dispersed leucite (Potassium alumino
silicate crystals) in a glassy matrix
Optec HSP (Optec High Strength Porcelain) (Jeneric
Pentron)
• Leucite reinforced feldspathic porcelain
• Condensed and sintered on a refractory die
• Moderate strength
• Retains its translucency apparently
• Flexural strength -140 MPa

Composition
Glass ceramic with leucite content of 50.6 wt%
dispersed in a glassy matrix
Primary uses
Inlays, Onlays, Crowns and Veneers

Fabrication
•Build up and contouring by conventional method on a
refractory die
•The leucite and glassy components are fused at 1020°C to
a dense structure reportedly having a compressive
strength of approximately 1,50,000 psi
•Body and incisal porcelain added to provide the desired
shade and translucency

Advantages
• Can be used as core material
• Good translucency
• Moderate flexural strength
• No special laboratory equipment needed
Disadvantages
• Potential marginal inaccuracy
• Potential to fracture in posterior teeth.
• May contribute to high abrasive effect

Hydrothermal ceramics
Introduced by Ryabov et al, Bartholmew, Bertschtein and
Stepanov and Scholze in 1970’s and 1980’s
• Low fusing porcelain containing hydroxyl groups in the glassy
matrix
• Increase in the thermal expansion and mechanical strength
•Termed hydroxyl addition as palsified layer which increases
chemical resistance, generates a smoother surface profile and
posses a unique capacity of healing surface flaws through the
ion exchange process
-Bertrchetein and Stepanor

The hydroxyl ions is added to the porcelain structure
through exposure to water or water vapour
2 types
•A single phase porcelain
Duceram LFC
•A leucite containing two phase material
Duceragold

Duceram LFC
• Low fusing hydrothermal ceramic of an amorphous glass
containing hydroxyl
• Greater density
• Higher flexural strength
• Greater fracture resistance
• Low hardness than feldspathic porcelain
• Ability to abrade the opposing natural tooth structure is
reduced

Fabrication
Two layers of ceramics to be applied
Base layer – Duceram MC
leucite containing porcelain
Followed by veneer – Duceram LFC

Method
• Duceram MC is condensed on a refractory die using
conventional powder slurry technique and sintered at 930°C
• Over this base layer, duceram LFC is condensed and
sintered at 660°C
• Highly polishable
Uses
• Can be employed for the fabrication of ceramic inlays,
veneers and full contour crowns

Advantages
• Greater density
• High flexural strength
• Greater fracture resistance
• Low abrasion
• Surface resistant to chemical attack
• Highly polishable
Disadvantages
• Low coefficient of expansion
• Hence cannot be directly sintered on the metallic
substructure
• Thus, an inner lining of conventional high fusing ceramic is

Castable ceramics
Glass ceramics are poly crystalline materials
developed for application by casting procedure using the
lost wax technique, hence referred to as ‘castable ceramic’
• Partially crystallized glass
• Show properties of both crystalline and amorphous
(Glassy) materials.
• They are fabricated in the vitreous state by controlled
crystallization using nucleating agents during heat
treatment

Castable Dental Glass Ceramics
Flucoromicas Apatite glass ceramics Other glass ceramics
Dicor Cera pearl Lithia
Calcium
Phosphate

DICOR
The term “DICOR” is a combination of the
manufacturers names - Dentsply International and corning
glass
Dicor is castable polycrystalline fluorine containing
tetrasilicic mica glass ceramic material, initially cast as a
glass by a lost wax technique and subsequently heat treated
resulting in a controlled crystallization to produce a glass
ceramic material

Composition
Major ingredients
SiO2 -> 45 – 70%
K2O -> 20%
MgO -> 13 – 30%
MgF2 (nucleating agent and flux 4 to 9%)
Minor ingredients
Al2O3 -2% (Durability and hardness)
ZrO2 - 7% (Fluorescing agent for esthetics)
BaO – 1-4% (Radiopacity)
Supplied as : Solid ceramic ingots
Dicor shading porcelain kit

Equipment
•Dicor casting machine
•Dicor ceramming furnace with ceramning trays
•Fabrication consists of mainly 2 steps
• Casting
•Ceramming

Casting
• Glass liquefies at 1350°C to such as degree that it can be
cast into mold using lost wax and centrifugal casting technique
• Wax pattern of proposed restorations invested in castable
ceramic investment
• Burned out in a conventional burn out at 900°C for 30minutes
• Placed in a special zirconium crucible and centrifugally cast in
the electronically controlled DICOR machine
• After coating, it is divested, sandblasted and carefully
separated from the spruce

DENTSPLY DICOR CASTING MACHINE

Ceramming
• The cast glass material is subject to single step heat
treatment – Ceramming
• Controlled crystallization
• This gives glass ceramic the special physical and
mechanical properties of DICOR
Method
• Casting is embedded in castable ceramic
embedment material (Gypsum – based) and placed
in a ceramming tray in the DICOR ceramming
furnace www.indiandentalacademy.comwww.indiandentalacademy.com

DENTSPLY CERAMMING MACHINE

Ceramming cycle
• 650 – 1075°C for 1 ½ hours and sustained upto 6 hours
following the ceramming process, a ceram layer of 25 – 100
μm thickness is formed on the surface of the DICOR
restorations
• According to the manufacturers laboratory manual, the rod
like crystals that form on the surface of the casting during
ceramming increase opacity
• Therefore, a shaded Dicor restoration should be viewed as a
non-homogenous material composed largely of the internal
castable glass ceramic veneer with a thick, hard cerammed
“Skin” covered with multiple layers of shading porcelainwww.indiandentalacademy.comwww.indiandentalacademy.com

CERAMMING TRAY CERAMMING FURNACE

Properties
• High compressive and tensile strength high modulus of elasticity
• Transparency
• Wear properties and co-efficient of thermal expansion closes to
that of dental enamel
Chameleon effect of Dicor
• The transparent crystals scatter the incoming light, the light and
also its colour, is distributed as if the light is bouncing off a large
number of small mirrors that reflect the light and spread it over the
entire glass ceramic
•Change color according to their surrounding, which enhances itswww.indiandentalacademy.comwww.indiandentalacademy.com

Decrease in plaque accumulation
Interferes with bacterial adhesion to different proteins
(Plaque) normally found on natural teeth due to following
reasons
• It has a smooth non porous surface
• Presence of an electrical charge inhibiting plaque
formation or fluoride in the chemical structure

Advantages
• Chemical and physical uniformity
• Excellent marginal adaptation
• Compatibility
• Uncomplicated fabrication
• Base of adjustment
• Excellent esthetics
• Relative high strength , surface hardness and occlusal wear
• Inherent resistance to bacterial plaque and biocompatible
• Low thermal conductivity
• Radio graphic density similar to that of dentinwww.indiandentalacademy.comwww.indiandentalacademy.com

Disadvantages
• Requires special and expensive equipments such as
Dicor casting machine, ceramming oven
Must be shaded / stained with low fusing feldspathic
porcelain which may be lost during occlusal adjustment,
during routine dental prophylaxis or through the use of
acidulated fluoride gels
Dicor plus - consists of a cast cerammed core and shaded
feldspathic porcelain veneer however, as Dicor plus is a
feldspathic porcelain that contains leucite, the abrasiveness
is similar to other feldspathic porcelain.

Castable Apatite Glass Ceramic
Cera Pearl
. Contains a glass powder distributed in a vitreous or non
crystalline state.
Composition
• CaO – 45%
• Phosphorous – 15%. Aids in glass formation
• Magnesium oxide – 5% -Decreases the viscosity
• Silicon dioxide – 35% - forms the glass matrix
• Other trace elements – nucleating agentswww.indiandentalacademy.comwww.indiandentalacademy.com

Chemistry
1460°C exposure to
CaPo4 Oxyapatite Crystalline(Amorphous
Hydroxypaptite
(HA) Moisture
ceramming

Physical properties
• Coefficient of thermal expansion : 11.0 x 10-6/oC.
• Youngs modulus – 103 Gpa
• Casting shrinkage – 0.53%
•Flexural strength similar to Dicor
•Biological properties – Dense material, chemically
stable, PH similar to natural enamel
•Non toxic / biocompatible

Fabrication
Casting
•Wax pattern of proposed restorations invested
•Following burnout, investment transferred to an automatic
casting machine
•Cera pearl crystals placed in the ceramic crucible, melted
under vaccum (1460°C) and cast 9151°C) into the mold
•Annealing done after 1 hour of casting
•Investment material around cast structure in removed by
sand blasting and Ultra sonically cleaned
• Annealed casting is reinvested for ceramming

Ceramming
• Ceramming oven preheated at 7500°C for 15 minutes
• After cast glass ceramic placed in the oven, the
temperature raised at the rate 50°C/min until it reaches
870°C held for 1 hour
• After crystallization, the casting is divested, cleaned by
sandblasting

Lithia based glass ceramic
Developed by Urgu
Composition : It contains mica crystals and Beta spodumene
crystals of LiO, A12O3.4SiO2 after heat treatment.
Calcium phosphate glass ceramic
• Reported by Kihara and others
• Combination of calcium phosphate and phosphosus
pentoxide plus trace elements
•Cast at 1050°C in gypsum investment mold
• Clear cast crown is converted to a crystalline ceramic by
heat treating at 645°C for 12 hourswww.indiandentalacademy.comwww.indiandentalacademy.com

Disadvantages
•Weaker than other castable ceramics
•Opacity reduces the indication for use in anterior teeth

Advantages of castable glass ceramics
• High strength
• Excellent esthetics
• Convenient procedures
• Favorable soft tissue response
• X-ray density allowing examination by radiograph
• Hardness and wear properties closely matched to those of
natural enamel.
• Similar thermal conductivity and thermal expansion to
natural enamel
• Dimensional stability

Machinable Ceramics
Pore free restorations can be alternatively produced by
machining blocks of pore free industrial quality ceramic
Digital systems (CAD/CAM)
* Direct
• Indirect
3 steps
• 3 dimensional surface scanning
• CAD – modeling of the restorations
• Fabrications of the restorations

Analogous systems (Copying methods)
•Coping milling / Coping grinding or Pantography systems
Two steps
* Fabrications of prototype for scanning
* Copying and reproducing by milling
Erosive techniques
* Sono erosion
* Spark erosion

C A D -C A M C e r a m ic s C o p y -M il l e d C e r a m ic s
M ac h in ab le C er am ic s
A ceramic
restoration
fabricated by use of
a computer aided
design & computer
aided milling
A process of milling
a structure using a
device that traces
the surface of a
metal, ceramic or a
polymer pattern and
transfers the traced
spatial positions to a
cutting station

CREATION OF A RESTORATION WITH TRADITION AND CAD/CAM TECHNIQUES
DesignDesignDesignDesign
restoration

Digital systems
• CAD/CAM milling uses digital information about the tooth
preparation or a pattern of the restorations to provide a
computer aided design (CAD) on the view monitor for
inspection and modifications
• The image is the reference for designing a restoration on
the view 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 for cutting the restorations from a
block of material www.indiandentalacademy.comwww.indiandentalacademy.com

Stages of fabrication
• Computerized surface digitization
• Computer aided design
• Computer assisted manufacturing
• Computer aided esthetics
• Computer aided finishing

Computerized surface digitizations
• Direct (at the tooth)
• Indirect methods
• Mechanical
• Optical sensors
Types
• Photogrammetry
• Move
• Laser scanning
• Computerized tomography (CT) scanning.
• Magnetic resonance imaging.
• Ultra sound
• Contact profiilometry

CAD-CAM technique for fabricating a ceramic restorations
Cavity preparation is scanned stero photogrammetrically using 3D miniature
video camera
Small micro processor unit stores the 3D pattern depicted on the screen.
Video display serves as a format for the necessary manual construction via
an electric signal
The microprocessor develops the final 3-D restorations from the 2D
constructions
The processing unit automatically deletes data beyond the margins of the
preparation
The electronic information is transferred numerically to the miniature 3 axis
milling device
Driven by a water turbine unit, the milling device generates a precision fitting
restorations from a standard ceramic block

Cerec 1 System
• 3 D video camera (Scan head)
• An electronic image processor (Video processor) with
memory unit (Contour memory)
• A digital processor
• A miniature milling machine (3 axis machine)

Optical impression
• A small hand held video camera with a 1 cm (scanner)
when placed over the occlusal surface of the prepared
tooth, emits infrared light which passes through an internal
grid containing a series of parallel lines
• The pattern of light and dark strips which falls on the
prepared tooth surface is reflected back to the scanning
head and onto a photo receptor, where its intensity is
recorded as a measure of voltage and transmitted as
digital data to the CAD unit

Procedure
• The prepared and surrounding tooth surfaces is
coated with CEREC powder
•The hand held camera is positioned over the
prepared tooth and an image of the preparation is
then simultaneously projected onto the screen
•The 3D scanning is triggered by the release of the
foot pedal
• Once the appropriate optical orientation is
generated, the operator can ‘freeze frame’ the
preparation into a static image

Designing The Restorations
• Proposed restorations designed by tracing frame lines on the
optical impression projected on the screen
• Cursor controlled by reverse mouse located on top of the unit
used to define the limits / boundaries
• Operator can carefully examine, edit and if necessary even
modify the pattern at any movement in the procedure
• Electronically designed proposed restorations can be viewed
as a 3D model on the monitor and stored automatically on the
program disk

Milling Of Ceramic Restorations
• Milled for 4-7 min
• Diamond wheel from premanufactured and standardized
ceramic block in the milling chamber of the CAM unit
• Homogenous & pore free

CAM unit
• A pump system with an attached water reservoir
located at the base of the mobile cast
• 5 liters of water cycled internally
• Microporous filler - traps any loosened diamond
particles

Procedure
• The appropriate ceramic block is selected
• Mounted on a metal stub, inserted into the milling unit and the
grinding operation initiated
•Grinding of ceramic restorations due by diamond disk/wheel with high
velocity water spray, which simultaneously cools and cleans the
milling disk
•Diamond wheel not only rotates but also translates up and down over
the porcelain block being milled
•A series of cuts or steps (200-400) are required for milling a ceramic
restorations
•The completed restorations falls to the bottom of the chamber from
where it can be readily retrieved

Additional Features
• Before milling process, screen displaces the dimension of
the restorations
• During milling operations - screen continuously informs the
operator of the percentage of completion
• A continuous read out displayed concerning the cutting
efficiency of the diamond wheel

Clinical shortcoming
•The occlusal anatomy had to be developed by the clinician
using flame shaped,fine particle diamond instrument and
conventional porcelain polishing procedures
•Inaccuracy of fit or large interfacial gaps
•Clinical fracture
•Relatively poor esthetics

Cerec 2 system
• Developed by Morman and
Brandestini - 1994
Major changes
• Enlargement of the grinding
unit from 3 axis to 6 axis
•
• Upgrading of the software
with more sophisticated
technology which allows
machining of the occlusal
surface

•Other technical innovation of Cercec 2
• Improved Cerec 2 Camera - new design, easy to handle detachable
cover, reduction in the pixel size / picture element to improve accuracy
and reduce errors
• Data representation in the image memory and processing increased by
8 times, while computing capacity is 6 times more efficient
• Magnification factor increased X8 to X12
• Visual control of video image –better
•Permits custom veneer preparation and class IV preparation with incisal
edge coverage
• Improved in rigidity and grinding precision by 24 times
• Improved accuracy of fit

Machinable ceramics are prefired blocks of
feldspathic or glass ceramics
Composition
Modified feldspathic porcelain or special pure alumino
silicate composition
Properties
•Excellent fracture and wear resistance
•Pore free
•Possess both crystalline and non crystalline phase

Ceramic CAD/CAM restorations are bonded to tooth
structure by etching the fitting surface for bonding to
enamel
Conditioning, priming and bonding
Etching (By HF acid) and primary (Silanating)
Cementing with luting resin

Two classes of machinable ceramics are
Fine scale feldspathic porcelain
Glass ceramics
Cerec Vitablock mark 1
• Feldspathic porcelain to be 1st used with cerec system
• Large particle size – 10-50 um
• Composition strength & wear properties similar to that of
metal ceramic restorations
Cerec Vitablock mark 2
• Feldspathic porcelain reinforced with Aluminium oxide
• Fine grain size - 4 um
•Abrasive wear of opposing tooth is reduced

Dicor MGC
• Machinable glass ceramic
• Composed of fluoromica crystals in a glass matrix
• Mica particles smaller - 2 um
• Greater flexural strength
• Softer than conventional feldspathic porcelain
•Less abrasion than cerec Mark I but more than Cerec mark II
• Available as Dicor MGC light and Dicor MGC dark

MGC-F (corning Inc)
• Tetrasilic mica glass ceramic with enhanced fluorescence
and machinability
Pro CAD
• High strength optimized leucite reinforced glass ceramic
material
•Available as blocks in different sizes and shades
•Suitable for all Cerec applications

Clinical advantages of the Cerec system
•Quality controlled ceramic porcelain can be placed in one visit
•Translucency and color of porcelain very closely appearance
the natural dental hard fissures
•Qualities of ceramic porcelain do not change by variation
•Wear resistant

Advantages of CAD/CAM
•Eliminates impression model making and fabrication of temporary
prosthesis
•No laboratory assistance
•Single visit restorations
•Void free porcelain restoration
•Better adaptation & no firing shrinkage
•Can fabricate a ceramic restorations at the chair side
•Correct dimension can be evaluated
•Glazing not required and can be easily polished
•Minimal abrasion
•Easy transport

Disadvantages
•Limitations in the fabrications of multiple units.
•Inability to characterize shades and translucency
•Inability to image in a wet environment.
•Incompatibility with other imaging system
•Extremely expensive and limited availability
•Lack of support for occlusal adjustment
•Technique sensitive
•Time and cost must be invested for mastering the technique
and the fabrication

CEREC 3
• Simplifies & accelerates the fabrication of ceramic
inlays, onlays, veneers,& quarter, half,& complete crowns
for anterior& posterior restoration
• Proper occlusion is established accurately& quickly
• Manual adjustment is reduced to minimum
• Network &multimedia ready& combination with an
intraoral color video camera
• Can be used with existing PC and the Cerec 2

• Cylindrical floor bur
&conical occlusal milling bur-
Flexible shaping technique
• Better adapted to tooth
preparation
• Replicate the occlusal
morphology better
• Provides longer life for the
diamonds
• More economical

Indirect method
Cicero system
Developed for the production of ceramic fused to metal
restorations
•Optical scanning
•Metal and ceramic sintering
•Computer aided crown fabrication techniques
The unique feature of this system is that it produces
crowns, FPD’s and inlays with different layers such as
metal and dentin and incisal porcelains

Analogous systems
Copy milling
Mechanical shaping of an industrially prefabricated ceramic
material
Copy milling includes fabrication of a prototype (proinlay or
crown) usually via impression making and model preparations
Based on the model, a replica of inlay / crown is made and
fixed in the copying device and transferred 1:1 into the chosen
material such as ceramic

Celay
•Used in both copy milling and CAD/CAM techniques
•Fine grained feldspathic porcelain used to reduce
abrasiveness
•Composition identical to that of cerec vita block mark II

Celay system
•First became commercially available in 1992
•It is a high precession, manually operated copy milling
machine

Method
•An impression prepared tooth is made and poured in die stone
•A prototype resin coping of the restoration called proinlay is fabricated on
the die using a blue light cured resin
•The cured resin phototype is removed form the die and fixed on the left side
of the relay unit using a special retaining device
•A fabricated ceramic blank is fixed in the carving chambers on the right side
of the relay unit
•The reference disk (Tracing tool) mechanically traces or scans the surface
of the prototype
•For milling a coping, the lumen of the coping is scanned and milled with
coarse hall and round tipped diamonds

•Produces slightly over sized restorations
•The final contour of the restorations is developed with 64 um grit
finishing diamond instrument
•External surface are finished with disks and the internal surfaces
with round tipped and sharp / fine tipped diamond stones
•Final fit of the machined inlay / coping is examined and internal
discrepancies are marked and reworked with repeated scanning
•The internal surface is either acid etched or air abraded before
silanization and cementation

Advantages
Processing time is considerably shorter
Higher flexural strength.
.

Erosion methods
Sono erosion – for ceramic restorations
Spark erosion - for metal restorations

Sono erosion
•Based on ultra sonic methods
•First, metallic negative moulds (so called sono trades) of the
desired restoration are produced, both from the occlusal as well as
from the basal direction
•Both sonotrades fitting exactly together in the equational plane of
the intended restorations are guided onto a ceramic blank after
connecting to an ultra sonic generation under slight pressure
•The ceramic blank is surrounded by an abrasive suspension of hard
particles, accelerated by ultrasonics, and thus erode the restorations
out of the ceramic blank

Spark erosion
•It refers to electrical discharge machining
•It may be defined as a metal removal process using a
series of sparks to erode material from a work piece in a
liquid medium under carefully controlled conditions
•The liquid medium usually is a light oil called the dielectric
fluid
•This fluid function as an insulator, a conductor and a
coolant and flushes away the particles of metal generated by
the spark

Advantages
•Not affected by metal hardness
•Adhesive characteristics of the work piece do not affect EDM
•Provides smooth bur – free surface
•Can be used to machine thin objects without distortion
•Can be used to make long, small diameter cuts
•Accurate to within 0.0001 inch

Dental ceramics/certified fixed orthodontic courses by Indian dental academy

Dental ceramics/certified fixed orthodontic courses by Indian dental academy

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