Ceramics

PRESENTED BY:
DR.MEENAKSHI SINGH
M.D.S 1st
YEAR
GUIDED BY
DR.S.K SINGH
DR.AJAY SINGH
DR.B.K TONDON

Dentistry has evolved from a curative to
a creative science in a very short span of
time.
The newest advancement in this
esthetic dentistry is the introduction of
all ceramic materials.

INTRODUCTION
Ceramics was originally referred to the art of fabrication of
pottery. The term derives from the greek word of
"keramos" which means "a potter or pottery". It is believed
that this word is related to the Sanskrit term meaning
"Burned Earth".
The earliest ceramic articles date back to 23,000 BC &
consisted of earthenware, stoneware & porcelain.
Porcelain was first obtained by fluxing white china clay
with china stone to produce a translucent material.

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 G.P.T 7,
Anusavice. OR
They are non-metallic, inorganic structures,
primarily containing compounds of oxygen with one
or more metallic or semi- metallic elements
(Aluminium, Calcium, Lithium, Magnesium,
Titanium, Potassium, Silicon, Sodium, Zirconium).
Dental ceramics may consist primarily of glasses,
porcelains, glass-ceramics or highly crystalline structures.

Ceramics may be classified into four categories according to
their composition
 Silicate ceramics( dental porcelain fall in this category)
 Oxide ceramics
 Non oxide ceramics
 Glass ceramics
Many dental ceramics have a crystal phase and a glass
phase based on the silica structure. This structure is
characterized by a Si-O tetrahedron in which a Si4+
cation is positioned at the center of a tetrahedron
with O-
anions at each of the four corners. The
resulting structure is not close-packed, and it has both
covalent and ionic characteristics. The SiO4 tetrahedra
are linked together by sharing their corners.

Porcelain is a special type of ceramic based on a specific dominant
composition that includes silica, alumina, and potassium oxide. These three
oxides are alloyed and produce a potassium aluminosilicate. Dental porcelain is
a very narrow range of these compositions.
Most dental porcelains are partially crystalline. Their bonding is mixed and
dominated more by covalent than ionic character. The composition includes
non-crystalline and crystalline phases. Dental porcelain is created, not by
directly mixing the three main oxides, but by mixing clay, feldspar, and quartz
that contain the oxides.
Dental porcelains are dominated by feldspar and tend to have more silicate matrix
in the final microstructure than dispersed crystalline phases. These are called
feldspathic porcelains.
Feldspathic porcelains are esthetic but not very strong. As the alumina content is
increased the amount of crystalline dispersed phase, particularly alumina rich
ones, is increased and the material becomes stronger. However, aluminous
porcelains are whiter and lack the translucency of feldspathic ones. Aluminous
porcelains are good for underlying cores while feldspathic ones are good for
esthetic veneers.

PROPERTIES OF CERAMICS
Dental porcelain is chemically very stable, and provides
excellent aesthetics that do not deteriorate with time. The
thermal conduction and the coefficient of thermal expansion
are similar to those of enamel and dentine, so in the presence of
a good marginal seal, marginal percolation is less likely to be a
problem.
• The material, being primarily a glass, lacks any fracture
toughness. The maximum strain that a glass can withstand
is less than 0.1%. Glasses are extremely sensitive to the
presence of surface microcracks and this represents
one of the major drawbacks in the use of dental porcelain.

REVIEW OF CERAMIC PROPERTIES
1. Physical Properties:
a. Intermediate density (1.0-3.8 gms/cc)
b. High melting point (= refractory)
c. Low coefficient of thermal expansion (12-15 ppm/°C)
2. Chemical Properties:
a. Low chemical reactivity
b. Low absorption and solubility
3. Mechanical Properties:
a.High modulus
b.Much stronger in compression(350-550Mpa) than tension( (~10X)
c.Brittle (low plastic deformation (<0.1%); low fracture toughness
d.Surface hardness (460 KHN),tooth
4. Biological Properties:
a. Relatively inert

Properties of Ceramic which make it desirable for Dental Use :
 Chemically inert
 Compatible with soft tissue- no hyperplastic or
inflammatory change with gingiva seen
 Resistant to sudden thermal change
 Provides good insulation
 Colour stability
Drawbacks of ceramics
1. Brittleness
2. Shrinkage during firing
3. Ability to abrade opposing tooth
4. They need to have accurate margins as they are fabricated
outside the mouth

Uses of ceramics in dentistry
Make denture teeth
Fixed partial dentures
Single unit crowns
Inlays and onlays
Labial veneers
Ceramic brackets used in orthodontics

History of dental ceramics
Fauchard in 1728,described the use of backed enamel in colour
and shade corresponding to natural teeth.
1774,Alexis Duchateau,constructed first set of mineral teeth.
Guisepangello Fonzi of Italy in 1808,introduced terrometallic
teeth.
Plantou in 1817,introduced porcelain denture teeth.
In 1825,Stockton began the production of porcelain teeth.
Porcelain inlays and crowns were developed by Wain in 1923 as
reported by Jones.

 In 1889,Dr Charles H Land filed the first patent for porcelain jacket
crown
 Glass ceramics was developed by Corning glass works.
 Weinstein and weinstein in 1962 described the formulation of
feldspathic porcelains .
 Vita Zahnfabrik in 1963 developed the first commercial porcelain.
 A significant improvement in the fracture resistance of porcelain
crowns was reported by Mclean & Hughes in 1965.
 MacCulloch in 1968 proposed the use of glass ceramics in
dentistry.
 O’Brien in 1985 developed magnesia core ceramic.

CAD CAM systems were developed in the early 1980’s .
Magnesia core ceramic was developed as an experimental material in
1985 (O'Brein, 1985).
Dr. Horn developed the platinum foil technique .
Calamia reported the refractory die technique.
Early 1990’s IPS Empress was developed and IPS Empress 2 was
developed in the late 1990’s.
In 1992 Duceram LFC was marketed .
Andersson and Oden developed Procera all ceram .
Johnson and Johnson developed the cerestore ceramics

Classification of ceramics
 According to their firing temperature
1. high fusing -1290 to 1370 degree C
2. medium fusing-1095 to 1260 degree C
3. low fusing -870 to 1065 degree C
 According to type
1. feldspathic or conventional porcelain
2. leucite reinforced porcelain
3. aluminous porcelain
4. glass infiltrated alumina
5. glass infiltrated spinel
6. glass ceramic
 According to use
1. porcelain for artificial teeth
2. jacket crown, veneer, and inlay porcelain
3. metal ceramics
4. anterior and posterior bridge porcelain

According to processing method
sintered porcelain
 cast porcelain
 machined porcelain
According to method of firing
 air fired i.e at atmospheric pressure
 vacuum fired i.e at reduced pressure
According to substructure material
 cast metal,swaged metal,
 glass ceramic,
 CAD-CAM porcelain,
 sintered ceramic core
According to esthetic role of porcelain:
 Opaque porcelain
 Body porcelain (incisal or enamel; gingival or dentin;
modifier)
 Stains or glazes

Processing of ceramic materials
 Ceramics are obtained by sintering fine ground particles. In the traditional
laboratory technique, these particles are applied onto the framework as a water
slurry dried and fired a process referred to as "HYDROPLASTIC FORMING".
 CERAMMING-By subjecting the material to specific temperature cycles, a
stronger crystalline phase is grown out of an initially glassy mass
 SLIP CASTING- randomly packed alumina crystals are lightly sintered so that
only the contact points of the alumina crystal fuse. The porous structure is then
infiltrated with molten glass drawn into the mesh by capillary action
 HEAT PRESSING- achieved by sintering under pressure thus decreasing the
porosity of the material and increasing strength. IPS EMPRESS and PROCERA
ALLCERAM are manufactured using this principle.

Ceramic processing methods
Feldspathic porcelain of traditional PFM restorations,
aluminous porcelain and pure alumina ceramic (Procera
all ceram )are condensed by vibration and dry pressed
and sintered at high temperatures.
Pressable ceramics (IPS Empress ,IPS Empress2, Finesse all
ceramic ,OPC,OPC-3G) when heated and subjected to
hydrostatic pressure flow in a mold and after removal and
divesting are then veneered.
Cast and cerammed crowns such as Dicor are made using
the lost wax technique. The molten glass is cast into a mold,
heat-treated to form a glass-ceramic, and colored with shading
porcelain and surface stains.

Slip cast ceramics (In-ceram spinel,In-ceram-
zirconia,In-ceram alumina),a slurry of liquid and
particles of alumina ,spinel,zirconia is placed on a
refractory die that draws out the water from the
slurry and the slip cast deposit is then sintered on
this die and then it is coated with a slurry of a glass
phase layer. During firing, the glass melts and
infiltrates the porous ceramic core.
For CAD CAM processes ,the ceramic block materials
are shaped into inlays or crowns using a CAD-CAM
system(CEREC)

H e a t
p a r t ic u la t e m a s s c o h e s iv e o b je c t
P O R O S IT Y
( I N C O M P L E T E
S I N T E R IN G )
SCHEMATIC DIAGRAM OF SINTERING PROCESS

METHODS OF STRENGTHENING CERAMICS
1.Minimize the effect of stress raisers:
Numerous minute scratches & other defects are present on the surfaces
of the materials. These surface flaws behave as sharp notches
whose tips may be as narrow as the spacing between several atoms
in the material.
When the induced mechanical stress exceeds the actual strength of the
material bonds, at the notch tip break, forming a crack.
Stress raisers are discontinuities in ceramic & metal-ceramic structures
and in other brittle materials that cause a stress concentration in
these areas.

Abrupt changes in shape or thickness in the ceramic contour can act
as stress raisers & make the restoration more prone to failure. Thus
the incisal line angles on an anterior tooth should be well rounded for
a ceramic crown.
Several conditions can cause stress concentrations.
• Creases or folds of the platinum foil or gold foil substrate that
become embedded in the porcelain leave notches that
act as stress raisers.
• Sharp line angles in the preparation also create areas of
stress concentration in the restoration.
• Large changes in porcelain thickness, a factor also determined by
the tooth preparation, can create areas of stress concentration

Increase the fracture resistance by one of the following
options:
1. Select stronger and tougher ceramics.
2. Develop residual compressive stress within the surface
of the material by thermal tempering.
3. Develop residual compressive stresses by matching
thermal expansion coefficients.
4. Reduce tensile stress by using stiffer supporting
materials.
5. Minimize the number of firing cycles.
6. Design the ceramic FPD with greater bulk and broader
radii of curvature
7. Adhesively bond ceramic crowns to tooth structure.

2.Develop residual compressive stresses:
One method of strengthening glasses and ceramics is the
introduction of residual compressive stresses within the
ceramic.
The metal and ceramic should be selected with a slight mismatch
in their thermal contraction, so that the metal contracts slightly
more than the porcelain on cooling from the firing to the room
temperature.
For the ceramic prosthesis the thermal contraction coefficient of
the core ceramic is slightly greater than that of the veneering
ceramic.
This mismatch leaves the porcelain in residual compression &
provides additional strength for the prosthesis.

A fundamentally different method of strengthening glasses
& ceramics is to reinforce them with a dispersed phase of
a different material that is capable of hindering a crack
from propagating through the material.
There are two different types of dispersions used to
interrupt crack propagation. One type relies on the
toughness of the particle to absorb energy from the crack &
deplete its driving force for propagation. The other relies on
a crystal structural change under stress to absorb energy
from the crack.

3.Minimize the number of firing cycles
The purpose of porcelain firing procedures is to densely
sinter the particles of powder together & to produce
a relatively smooth, glassy layer (glaze) on the surface.
In some cases, a stain layer is applied for shade adjustment
or for characterization such as stain lines or fine cracks.
Leucite, is a high expansion crystal phase, which can greatly
affect the thermal contraction coefficient of the porcelain.

Some porcelains undergo an increase in leucite crystals after
multiple firings that will change their thermal expansion
coefficients.
If the expansion coefficient increases above the value for the
metal, the expansion mismatch between the porcelain & the
metal can produce stresses during cooling that are sufficient to
cause immediate or delayed crack formation in the porcelain.

4.MINIMIZE TENSILE STRESS THROUGH OPTIMAL DESIGN OF CERAMIC
PROSTHESES:
 Sharp line angles in the preparation will create areas of stress
concentration in the restoration. Because the forces on anterior
teeth are relatively small, the low to moderate tensile stresses
produced can be supported by ceramic crowns more safely.
• If there is a great amount of vertical overlap (overbite) with
only a moderate amount of horizontal overlap (overjet), high
tensile stresses can be produced.

•.
The tensile stresses in a ceramic FPD can be reduced by usinga
greater connector height and by broadening the radius of
curvature of the gingival embrasure portion of the inter proximal
connector.
However, a connector height greater than 4mm makes the
anatomic form in the buccal area of a posterior FPD too bulky &
unaesthetic.
One way to reduce tensile stresses on the cemented surface in the
occlusal region of ceramic inlays or crowns is to use the
maximum occlusal thickness as possible. This thickness is
typically 2.0 mm.

5.Ion exchange:
K.J Anusavice ,C.Shen ,and R.B.Lee: Strengthening of feldspathic
porcelain by ion exchange and tempering :
J Dent Res 71(5):1134-1138,May,1992
“The study was carried out on seven feldspathic porcelains to see the
effectiveness of thermal tempering and ion exchange on crack growth
and bi-axial flexural strength. The results showed that tempering
treatment was more effective in strengthening porcelain than was the
ion exchange process as measured by the bi-axial flexural strength and
that ion exchange process yielded a surface that was more resistant
to crack initiation than was yielded by thermal tempering.”

The ion - exchange process is sometimes called CHEMICAL TEMPERING and
can involve the sodium ion since sodium is a common constituent of a variety
of glasses and has a relatively small ionic diameter.
If a sodium - containing glass article is placed in a bath of
molten potassium nitrate, potassium ions in the bath exchange
places with some of the sodium ions in the surface of the glass
article and remain in place after cooling.

Since the potassium ion is about 35%larger that the sodium ion,
the squeezing of the potassium ion into the place formerly
occupied by the sodium ion creates very large residual
compressive stresses.
The product 6C Tuf-Coat was potassium rich slurry that
could be easily applied to a ceramic surface and when heated
to 450 O C for 30 min (in a standard porcelain furnace) caused a
sufficient exchange between the potassium ions in the slurry
and the sodium ions in the ceramic.

5.Thermal tempering :
The most common method for strengthening glass is by thermal
tempering. Thermal tempering creates residual surface
compressive stresses by rapidly cooling (quenching) the surface
of the object while it is hot and in the softened (molten) state.
This rapid cooling produces a skin of rigid glass surrounding a
soft (molten) core.
As the molten core solidifies it tends to shrink, but the outer
skin remains rigid.
For dental applications, it is more effective to quench hot glass-
phase ceramics in silicone oil or other special liquids rather than
using air jets that may not uniformly cool the surface.
This thermal tempering treatment induces a protective region
of compressive stress within the surface.

6.Dispersion strengthening:
A method of strengthening glasses & ceramics is to reinforce
them with a dispersed phase of a different material i.e. capable
of hindering a crack from propagating through the material.
This process is referred to as dispersion strengthening.
Toughening depends upon the crystals type, its size, its volume
fraction, the interparticle spacing, and its relative thermal
expansion coefficient relative to the glass matrix.
When a tough, crystalline material such as alumina (Al2O3) 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.

8.TRANSFORMATION TOUGHENING :-
Dental ceramics are strengthened & toughened by a variety of
dispersed crystalline phases including alumina (Vitadur Alpha,
Procera Allceram, In-Ceram alumina), leucite (Optec HSP, IPS
Empress, OPC), tetrasilicic fluormica (Dicor, Dicor MGC), lithia
disilicate (OPC3G, IRS Empress 2), magnesia-alumina spinell
(In-ceram spinell).
 Dental ceramics based primarily on zirconia crystals (Cercon &
Lava)undergo transformation toughening that involves a
transformation of ZrO2 from a tetragonal crystal phase to a
monoclinic phase at the tips of crack that are in regions of
tensile stress.

SHADE SELECTION AND MANAGEMENT
Light sources:
 Shade selection should not be made using daylight,
because daylight subjected to constant changes
 The color of the operatory can also affect shade
selection. Walls and cabinets should be glossy
enough to maintain brightness without causing a
glare. It is recommended that the color of the walls
and ceiling be white or off-white.
 The dentist should be concerned with "blue fatigue:'
this occurs when the eye is unable to differentiate
between the various shades of blue. However, blue
fatigue increases sensitivity to yellow therefore, to
improve shade selection in the yellow range, the
operator should stare at a blue card or patient napkin
between shade comparisons.

Problems with shade guides:
1. Porcelains do not match the shade guide that they are
being compared to .
2. Shade variations occur between different die lots of
porcelain from the same manufacturer.
3. Shade guide tabs are 4-5 mm thick compared to the
thin 1.5 mm piece of porcelain used for the restoration.
4. Shade guides are not always made with fluorescent
porcelain ,which causes inconsistencies in color
matching.
5. It is difficult to predict the final shade after the
layering of opaque, dentin and enamel.
6. Guide tab lack a metal backing when using porcelain-
fused to metal restorations.
7. Shade tabs are condensed differently than porcelain
used for final restorations.

Shade selection guidelines:
There are a number of methods that can be employed to intensify the
shade selection. They are as follows:
If patient is wearing bright clothing ,drape him or with a neutral
colored cover.
Having patient remove lipstick or other makeup.
Clean the teeth and remove all stains and debris.
Have patient’s mouth are dentist’s eye level.
Determine the shade at the beginning of the appointment to
avoid ocular fatigue.
Shade comparisons should be performed at five second interval so
as not to fatigue the cone cells of the retina.

7. Obtain value levels by squinting.
8. Compare shade under varying conditions (wet vs dry
lips: retracted vs pulled down lips).
9. Use the canine as reference for shade because of the
highest chroma of the dominant hue of the teeth.
10. Select a shade of lower chroma and higher value,if unable
to match shade precisely.
11. Grind off the necks of the shade tabs because they tend to
be darker than the rest of the shade tab.

R.Duane Douglas ,DMD,MS,and Jane D.Brewer,DMD,MS
(Faculty of Dentistry , University of
Manitoba,Winnipeg,Manitoba,Canada) :
Acceptability of shade differences in metal ceramic crowns:J Prosthet
Dent 1998;79:254-60
Purpose: The CIELAB colorimetric system was used to study the
relationship between measured colour differences and human
observer assessment of colour differences in metal ceramic crowns.
Results :Correlations between instrumental and vital assessment of
colour differences in the crown pairs did not disagree in all
dimensions of colour space.
Conclusion: acceptability thresholds were found to be dependant on
chromaticity. Observers were more sensitive and critical of crowns
whose color differed in redness as opposed to crowns whose color
differs to the same extent in yellowness.

3-D SHADE GUIDE SELECTION
How to select the shade with the VITAPAN 3D-
Master Shade Guide
There are three distinct steps: -
 determine lightness-darkness =Value
 determine intensity of colour =Chroma
 determine colour = hue

Step 1 .
Select one group from the five lightness groups-
Three things are clearly visible.
A scale from lightest to darkest across the full width of the
shade guide.
This light  dark scale is divided into 5 separate ,
uniformly spaced groups of lightness-1,2,3,4,5
All shade tabs within one group have the same lightness.
Human dentition progressively darkens with increasing age.
This can be an indicator and assist in choosing the
lightness group
i.e teen = group1 adult =group 2 middle age = group 3
older = group4 elderly =group 5

In each of the groups there is one shade tab which is
positioned more prominent and higher than the
others in its group.
These 5 tabs can be used to select the appropriate
lightness group. Each is numbered MI with its group
number preceding [i.e 1MI ,2 MI, 3 MI, 4MI,5MI], rather
than trying to pick up the appropriate MI tab from the
five , decide by eliminating those which are obviously
too light or too dark.
The lightness group selection is best accomplished with
the patient standing in subdued lighting.In this first
step ,colour is not being selected but rather , the
appropriate level of lightness is selected.(group
1,2,3,4,5)
Finally record the number of selected group[1,2,3,4,5] .
Intermediate selections are recorded as 1.5/2.5etc

Step 2 (good quality colour balanced lighting
is necessary for steps 2 and 3)
Select the chroma = colour saturation or
intensity
From the group selected in step 1, remove the
middle stick ‘M’ and fan out three blades .
Choose which of the three tabs most closely
correspond to the body of the standing teeth in
terms of colour intensity [i.e weak – medium-
strong]
We are selecting “ intensity or strength colour” –
NOT COLOUR
Record choice 1-2 or 3.Intermediates can also be
selected and recorded as 1.5,2.5

Step 3 Select the hue-
Natural unmodified dentition ranges in hue from a
strong yellow to a faint yellow to reddish / brownish.
The letter below each stick on the shade guide base
indicate the hue as follows.
L =left side of the group = yellowish hue
M= middle of the group =middle hue [discernable
yellow or red]
R= right side of the group = reddish hue
 Look at the body of the patient’s teeth and decide if a
yellowish or reddish /brownish influence is visible . If
neither can be seen, select stick ‘M’.
Record your choice L,M,R
Remove the selected hue stick from the group and
compare with the patients teeth to verify your choice.

Numbering of shade tabs
The first number of a shade is always and only
the group number.
 The letter is the hue
 The remaining number is the chroma
Example: 3M2 = VALUE 3/HUE M/ CHROMA 2
After selecting the group in step 1, the remaining
selection of chroma and hue are made solely from
within the same group .

 A good working definition for a ceramic is any material that is composed primarily of a metal and
non-metal composition. Porcelain is a special type of ceramic based on a specific dominant
composition that includes silica, alumina, and potassium oxide. These three oxides are alloyed and
produce a potassium aluminosilicate. Dental porcelain is a very narrow range of these compositions.
 Most dental porcelains are partially crystalline. Their bonding is mixed and dominated more by
covalent than ionic character. The composition includes non-crystalline and crystalline phases.
Dental porcelain is created, not by directly mixing the three main oxides, but by mixing clay, feldspar,
and quartz that contain the oxides. Dental porcelains are dominated by feldspar and tend to have
more silicate matrix in the final microstructure than dispersed crystalline phases. These are called
feldspathic porcelains. Feldspathic porcelains are esthetic but not very strong. As the alumina
content is increased the amount of crystalline dispersed phase, particularly alumina rich ones, is
increased and the material becomes stronger. However, aluminous porcelains are whiter and lack the
translucency of feldspathic ones. Aluminous porcelains are good for underlying cores while
feldspathic ones are good for esthetic veneers. Dental porcelains are limited severely by their defects,
particularly pores which originate cracks.

DENTAL PORCELAIN
IT IS A VITREOUS CERAMIC BASED ON SILICA NETWORK AND
POTASH FELDSPAR OR SODA FELDSPAR.
PIGMENTING OXIDES – Iron or nickel oxide(brown),copper
oxide(green),titanium oxide(yellowish brown),manganese
oxide(lavender),and cobalt oxide(blue).
OPACIFIERS – Cerium oxide, zirconium oxide, titanium oxide, or tin
oxide.
GLASSES
FLUXES
GLASS MODIFIERS-Na,K,Ca,water,boric oxide
BINDERS –starch and sugar
Porcelain is a ceramic material formed of infusible elements
joined by lower fusing materials. Most dental porcelains are
glasses and are used in fabrication of teeth for dentures, pontics
and facings, crowns, inlays, onlays and other restorations

FELDSPATHIC PORCELAIN
Feldspars are used in the preparation of many dental porcelains
designed for metal ceramic crowns and many dental glasses and
ceramics.
Feldspathic porcelains contain a variety of oxide
components,including silica(52-62%),alumina(11-16%),sodium and
potassium oxide, and certain additives,including lithium and boric
oxide.
These ceramics are called porcelain because they contain a glass
matrix and one or more crystal phases.They cannot be classified as
glass ceramics because ,crystal formation does not occur, through
controlled nucleation and crystal formation and growth.

• When potassium feldspar is mixed with various metal oxides and fired
to high temperatures,it can form leucite and a glass phase that will
soften and flow slightly.
• The softening of this glass phase during porcelain firing allows the
porcelain particles to colaesce together(liquid phase sinering) to form
a dense solid.
• When feldspar is heated to a temperature between 1150-1530 C,it
undegoes incongruent melting(forming liquid and a crystalline
material) to form crystals of leucite in a liquid glass.
• This tendency of feldspar to form leucite during melting is used to
advantage in the manufacture of porcelains for metal bonding.

There are four types of veneering ceramics
Low fusing ceramics(feldspar and nepheline syenite
based porcelain)
Ultra low fusing ceramics(porcelains and glasses)
Stains
Glazes(self and add on glazes)

Boric oxide acts as a glass modifier , it decreases the
viscosity ,lowers the softening temperature and
forms its own glass network.
Alumina can take part in glass network to alter the
softening point and viscosity
Pigmenting oxides are added to obtain the various
shades needed to stimulate natural teeth, examples:
iron or nickel oxide (brown) , copper oxide (green) ,
titanium oxide (yellowish brown), of cerium
manganese oxide (lavender), cobalt oxide (blue)
Opacity may be achieved by the addition
oxide,zirconium oxide, titanium oxide or tin oxide.

CAPTEK TM
A NEW CAPILLARY
CASTING TECHNOLOGY FOR
CERAMOMETAL
RESTORATIONS

CAPTEK tm
A NEW CAPILLARY CASTING
TECHNOLOGY FOR CERAMOMETAL RESTORATIONS
 Captektm
restorations include inlays , onlays, crowns, anterior and
posterior prostheses that are based on Captek TM
precious –metal
understructure veneered with bake on porcelain.
 Captektm
alloys are made of two major components –
1. When heated, forms a microscopic dimensional network of
capillaries
2. When melted, flows to these capillaries.
 Captektm
system includes three pairs of materials that form
composite metals:
1. Captektm
P and Captektm
G are used for crown copings and fixed partial
denture abutments.
2. CapconTM
and CapfilTM
are used to connect copings and pontics to a
prosthetic structure
3. Captek repair pastetm
and CapfilTM
are used to form extensions and
additions on the various CaptekTM
structures.

CAPTEK PTM
Captek PTM
platinum colored strips contain metal particles of less
than 30 mm and binders. The strips come in two thickness: one
for incisors, canines and premolars & one for molars.
CAPTEK GTM
Captek GTM
is applied over the processed Captek PTM
and it comes
in two thickness , for anterior teeth and for molars. It contains
fine particles with 97 % pure gold content and binders and 2.5
mt% silver sections of Captek GTM
are cut and fixed with the same
firing cycle in the porcelain furnace

CAPBONDTM
CapbondTM
is a gold based, gold –colored ceramometal
bonder.CapbondTM
is used as a very thin point- on layer
that forms a fine and open gold colored sponge. Porcelain
flows into the sponge like surface to form a strong bond.
CAPTEK REPAIR PASTETM
This material allows additions and corrections on CaptekTM
coping after they are recovered from the refractory die.

Fabrication Procedure
Duplicate the working die in the special refractory material.
Cut a piece of the gold-platinum-palladium impregnated wax sheet.
Adapt the foil to the die. Then it is fired to 1075 C (1965 F), forming a
porous metal coping.
Adapt the second gold-impregnated wax and refire. Capillary action
draws the gold into the porous gold-platinum structure to form the
finished coping.
Build up the opaque body and incisal porcelains in a manner similar
to that for a conventional metal-ceramic crown.
Glaze the completed restoration and polish the metal foil at the
margin. The procedure has been adapted for FPDs.

Reduced thickness Captektm
metal and thin opaque layers make
it possible to achieve acceptable margins with a total metal and
ceramic thickness of 0.3 - 0.5mm. A thickness of 0.5 - 0.7 mm
yields pleasing esthetics on the labial aspect of anterior crowns
and a thickness of 0.7 - 1.00 mm provides optimal porcelain
thickness.
For best results, premolars & molars should not be thinner than
0.7 mm near the margins. As recommended for conventional
cast metals & porcelain, the occlusal surfaces of premolars &
molars should be at least 1.2 mm thick.
The minimal thickness possible with esthetic Captek crowns
helps present over contouring of the porcelain and enables
normal emergence profile with conservative tooth reduction.

Electroformed
The Helioform HF 600 system uses an electroforming
technique to produce a thin pure gold coping. The gold is
deposited on polyurethane dies that are coated with a
silver spacer using computer-controlled plating equipment
to control thickness. The coping is coated with a noble
metal paste primer before porcelain application.
Electroforming enables very good marginal adaptation
(better than conventional casting). The system has been
adapted for FPDs.

Step-by-step Procedure
1.Duplicate the working die with the poly-urethane material.
2.Drill the polyurethane and glue the electrode into the die.
3.Apply an even coat of the silver spacer to the preparation
and allow it to dry.
4.Insert the dies into the plating equipment. A magnetic stirrer
ensures circulation of the cyanide-free gold sulfite solution.

5. Turn on the electric current, and gold will be deposited on
the die at an approximate rate of 0.02 mm per hour.
6. Remove the plated copings by heating the dies and remove
the silver spacer with nitric acid or air abrasion.
7. Trim flash from the margin with an abrasive silicone wheel
and seat the coping on the die.
8. Air-abrade the surface and apply the special bonding paste
before porcelain application.

Aluminous porcelain
 A method of bonding porcelain to metal makes use of tin oxide on platinum
foil.The objective of this technique is to improve the esthetics, by a
replacement of the thick metal coping with a thin platinum foil,thus allowing
more room for porcelain.
 The method consists of bonding aluminous porcelain to platinum foil copings.
 Attachment of the porcelain, is secured by electroplating the platinum
foil ,with a thin layer of tin and then oxidising it in a furnace to provide a
continuous film of tin oxide for porcelain bonding.
 The rationale is that the bonded foil will act as an inner skin on the fit
surface to reduce subsurface porosity and formation of microcracks in the
porcelain ,thereby increasing the fracture resistance of the crowns and
bridges.
 They provide a slightly better aesthetics for anterior teeth than are the metal
ceramic crowns that employ a metal coping
 However ,the strength of the core porcelain used for alumina –reinforced
crown is inadequate to warrant its use for posterior teeth.

These are based on the principle of dispersion
strengthening i.e.dispersing alumina crystals of
high strength in glass matrix.
The concentration of alumina crystals ranges
from 40-50%
Flexural strength is raised to 120-150 Mpa as
compared to 60Mpa of feldspathic porcelain.

ALUMINOUS PORCELAIN CROWNS
(PORCELAIN JACKET CROWN)
McLean AND Hughes in
1965 developed an alumina
reinforced porcelain core
material for the fabrication
of ceramic crowns.

Compaction
 The production of a porcelain jacket crown involves three technical
stages:
 In the construction of a porcelain jacket crown, the porcelain powder is
mixed with water and made into a paste. This paste is applied to the die,
which has been coated before hand with a very thin platinum foil to
allow the porcelain crown to be separated from the die and transported to
the furnace.
 The powder is mixed with water and a binder to form slurry, which can be
applied to the die in a number of ways, such as spatulation, brush
application, whipping or vibrating, all of which are aimed at compacting
the powder. The objective of these condensation techniques is to remove
as much water as possible, result is a more compact arrangement with a
high density of particles that minimizes the firing shrinkage.

The particle size and shape are
extremely important as they affect the
handling characteristics of the powder
and have an effect on the amount of
shrinkage on firing.
The binder helps to hold the particles
together, as the material is extremely
fragile in this so-called GREEN STATE
Three basic types of porcelain powder
are used :
opaque shade , dentine shade ,enamel
shade

FIRING
LOW BISQUE STAGE(650-1200O
C)-when the porcelain
begins to fuse, continuity is achieved at points of contact
between the powder particles. The material is still porous
and this state is the low bisque stage.
3. GLAZING
There are two ways in which it can be achieved:
OVERGLAZE
 Glasses that fuse at low temperatures are applied to the
crown after construction, and a short period at a relatively
low temperature is sufficient to fuse the glaze.
SELFGLAZE
 Final firing of the crown under carefully controlled
conditions fuses the superficial layer to an impervious
surface glaze. In this method, porcelain is heated to its fusion
temperature and maintained for 5 min.

The technique presented is a practical,
predictable, and accurate method of
constructing an aluminous porcelain jacket
crown without a platinum matrix.
Advantages :
Elimination of the platinum foil matrix.
Ease of fabrication and accuracy of fit.
Edwin J.Riley,D.M.D,Ralph B.Sozio,D.M.D:
Precision porcelain jacket crown technique: J
Prosthet Dent ,volume 34, number
3,September 1975,(346-50)
CROSS SECTION OF A METAL CERAMIC CROWN

Technique:
• Using any satisfactory technique, obtain , an impression of
the prepared tooth and fabricate a master die.
• Trim the dies and make an elastomeric impression of the
prepared dies.
• Pour a non-contaminating ceramic material into the
impression, providing the refractory die with an adequate
base.The powder-liquid ratio employed is 3 gm of powder to
1cc of liquid. This ratio provides adequate strength and
optimum handling characteristics.
• After seating for one hour, separate the die. Separation is
easily accomplished by directing an air stream between the
die and the impression.
• Paint a ceramic metal agent on the refractory die(to
avois shrinkage of die?) ,to the margin , providing a thin
uniform layer.

• Fire the refractory die (firing cycle :dry in front of the muffle
for two minutes and then vacuum fire at 1600 or 2048O
C
• If bare areas are observed ,apply a second application of the
ceramic metal agent, and fire using the same firing cycle.
• Apply aluminous porcelain core material ,condense it and
fire it on the the treated refractory i.e as recommended by
the manufacturer .
• As expected cracks are encountered in the aluminous
porcelain with the first firing due to its inherent
shrinkage. The ceramic metal agent , however remains
intact and fuses to the aluminous porcelain, preventing
loss of adaptation. Fill the cracks , and fire the die as in
step no. 8

• Recover the core from the die with a blunt instrument under running
water and ultrasonic cleaner. Thus , the refractory die is destroyed ,
leaving an aluminous core lined with the ceramic metal agent.
This core can now serve as a coping.
• Return the coping to the working cast. Apply a suitable match
of veneering porcelain , condense it , and fire it as recommended by
the manufacturer.
Coat the master cast die with a thin layer of petroleum jelly to prevent
subsequent intrusion of porcelain and condense it. Normally, the
crown can be fired on ordinary stagger tray. However , to prevent
any possible distortion on extremely thin aluminous cores, it is
suggested that a second refractory die be utilized as a custom
tray during subsequent firings.
Shaping and adjusting can be performed at this time , and the
restoration can be stained and glazed

Master model with dies Platinum foil adapted to die
Dentin Ceramic additions
Finished Cores
Unsintered Crowns

Finished Crowns on dies Post-Cementation

THE CASTABLE AND MACHINABLE GLASS
DICOR was the first available castable ceramic marketed by Dentsply
International. Dicor is a castable glass that is formed into an inlay, facial
veneer, or a full crown restoration by a casting process similar to that
employed for metals.

Dicor glass ceramic contains about 55 volume % of
tetrasilicic fluormica crystals. The ceramming
process results in increased strength and toughness,
increased resistance to abrasion, thermal shock
resistance, chemical durablity and decreased
translucency.
Dicor MGC is a higher quality product that is crystallized
by the manufacturer and provided as CAD - CAM blanks
or ingots.
Advantages of Dicor:
Ease of fabrication
Improved aesthetics
Minimal processing shrinkage
Good marginal fit

Moderately high flexural strength
Good marginal fit
Low thermal expansion equal to that of tooth structure
Minimal abrasiveness to tooth enamel
Disadvantages of Dicor:
Inability to be colored internally
Its limited use in low stress areas
DICOR PLUS AND WILLI’S GLASS –are two veneering materials
to improve the colour of Dicor crowns.

Wax pattern Investing
Burnout
450 0
C for 12 hr
17500
C for 12hr
Centrifugal casting machine
25000
F
Cast glass coping
Crystallised glass coping (after
ceramming) 19000
F for 1 ½ hr
Finished crown

PRESSABLE GLASS CERAMICS
 IPS EMPRESS is a glass - ceramic provided as core
ingots that are heated and pressed until the ingot
flows into a mold. It contains a higher concentration
of Leucite crystals that increase the resistance to
crack propagation (fracture).
 IPS EMPRESS AND IPS EMPRESS 2 are typical
products of several other leucite reinforced and lithia
disilicate reinforced glass ceramics respectively.
 The use of glass ceramics in dentistry was first
proposed by MacCulloch in 1968.

OPC is a leucite containing ceramic andOPC is a leucite containing ceramic and
OPC 3G contains lithia disilicate crystalsOPC 3G contains lithia disilicate crystals

Advantages :
1. Lack of metal
2. Translucent ceramic core
3. Moderately high flexural strength
4. Excellent fit and aesthetics
Disadvantages:
1. Potential to fracture in posterior areas
2. The need to use a resin cement to bond the crown
micromechanically to tooth structure
IPS EMPRESS

Wax pattern
Investing
Burnout 8500
C Ceramic ingots
Pressing under vaccum 11500
C
Sprue removal

Full contour wax pattern Cut-back
Investing
In-got pressing

IN-CERAM ALUMINA, IN-CERAM SPINELL AND IN-
CERAM ZIRCONIA(SLIP CAST CERAMMING)
 The flexural strength values of the glass-infiltrated core materials are
approx.
 350 MPa for In-Ceram spinell (ICS),
 500 MPa for In-Ceram Alumina (ICA), and
 700 MPa for In-Ceram Zirconia (ICZ) compared with strengths of
 100-400 MPa for Dicor, Optec Pressable Ceramic, IPS Empress and IPS
Empress 2.
 A slurry of one of these materials is slip-cast on a porous refractory die
and heated in a furnace to produce partially sintered coping or
framework.The partially sintered core is infiltrated with glass at 1100c
for 4 hours to eliminate porosity and to strengthen the slip cast core.
 The initial sintering process for the alumina core produces a minimal
shrinkage because the temperature and time are sufficient to cause
bonding between particles and to produce a desired level of
sintering.Thus the marginal fit and adaptation of this core material
should be adequate because little shrinkage occurs.

In-ceram spinell is indicated for use as
anterior single unit inlays, onlays,crowns and
veneers
In-ceram alumina is indicated for anterior
and posterior crowns and anterior three unit
FPD’s
In-ceram zirconia is indicated for posterior
crowns and FPD’s.Because of its high level of
opacity it is not recommended for anterior
prosthesis.

Collective Advantages of the three glass infiltrated core
materials are:
Lack of metal
Relative high flexural strength and toughness
Ability to be used successfully cemented with any
cement
In-ceram spinell is the most translucent and consists of
glass infiltrated magnesium spinell
In-ceram zirconia contains 30 wt% zirconia and 70 wt%
alumina
In- ceram alumina contains 70 wt% alumina and 30 wt%
sodium lanthanum glass

INCERAM ALUMINA ,INCERAM SPINELL AND
INCERAM ZIRCONIA

Advantages of ICA include:
1. A moderately high flexural strength and fracture
toughness
2.A metal free structure
3.Ability to be used successfully with conventional luting
agents
Disadvantages of ICA include :
1. marginal adaptation may not be too good
2. relative high degree of opacity
3. inability to be etched
4. technique sensitivity
5. relative great amount of skilled labour

STEPS FOR FABRICATING IN-CERAM PROSTHESIS
1. Prepare teeth with an occlusal reduction of 1.5 to 2 mm and a heavy
circumferential chamfer(1.2mm)
2. MAKE AN IMPRESSION AND POUR two dies
3. Apply alumina on a porous duplicate die
4. Heat at 120C for two hours to dry alumina
5. Sinter the coping for 10 hrs at 1120C
6. Apply a sodium lanthanum glass slurry mixture on the coping
7. Fire for 4 hrs at 1120C to allow infiltration of glass
8. Trim excess glass from the coping with diamond burs
9. Build up the core with dentin and enamel porcelain
10.Fire in oven,grind in the anatomy and occlusion,finish, and glaze

Al2O3 slip
Glass infiltration
Vita Inceramat3 Vaccumat 4000 Premium

Working model Duplication
In-Ceram refractory
dies
In-Ceram application Al2O3 slip Vita inceramat
10 hrs 1120 0
C- 2hrs
Shrinkage of dies Glass infiltration 4hrs
11000
C
Application of body and
incisal porcelain

PROCERA ALL CERAM
•The Procera Allceram crown is composed of densely sintered,
high-purity aluminium oxide core combined with a compatible
Allceram veneering porcelain.
oThis ceramic material contains 99.9% alumina, and its hardness is
one of the highest among the ceramics used in dentistry.

Step-by step Procedure
Tooth preparation follows all-ceramic guidelines.
The cast is made in the conventional way, but the die is
ditched to make the margin easier to identify
during scanning.
The die is mapped using a contact scanner.
The shape of the prepared tooth is transferred to the
computer screen .
The design of the restoration is transferred to the
manufacturer via computer line.
The production process starts with milling an
enlarged die to compensate for the sintering
shrinkage.

An enlarged high-alumina coping is milled that
shrinks to the desired shape after sintering.
The coping is returned to the laboratory, and body
and incisal porcelains are applied in the conventional
manner.

PROCERA ALLCERAM
Procera Allceram can be used forProcera Allceram can be used for
anterior and posterioranterior and posterior
crowns, veneers, onlays & inlays.crowns, veneers, onlays & inlays.

A unique feature of the Procera systems is the ability
of the Procera scanner to scan the surface of the
prepared tooth and transmit the data to the
milling unit to produce an enlarged die through a
CAD-CAM process. The core ceramic form is dry
pressed onto the die,and the core ceramic is then
sintered and veneered.Thus the usual 15-20% shrinkge
of the core ceramic during sintering will be
compensated by constructing an oversized ceramic
pattern,which will shrink during sintering to the
desired size to accurately fit the prepared tooth.

MAGNESIA - BASED CORE PORCELAIN
 Magnesia core ceramic was developed as an experimental material in
1985 (O' Brien - 1985). Its high thermal expansion coefficient (14.5 x 10-
6/0C) closely matches the of body & incisal porcelains designed for
bonding to metal (13.55 x 10-6/0C).
ADVANTAGES:
•Adequate strength for most anterior crowns.
•Esthetics superior to PFM for a given shade & technician
(no metal margins, discoloration)
•No risk in choosing alloy.
DISADVANTAGES :-
• Not used for fixed partial dentures.
• Requires learning to do good shoulder preparation

INJECTION-MOLDED HIGH-LEUCITE PORCELAIN
In this process high-leucite porcelain ingot cylinders are
heated to 115O 0
C to produce a plastic state. Then, the ingots
are pressure-injected into the investment molds formed by
the lost wax process for crowns, inlays-onlays and veneers.
• Due to the relatively high leucite content and
pressure forming process, the flexural strength
of porcelain formed by this process is around 200 MPa.
•The advantages of the process are good fit
and higher strength for the resulting restorations.

PORCELAIN REPAIR
The general method for repair is as follows :-
Establish a dry field.
Remove the surface of adjacent remaining porcelain with
an abrasive bur.
Treat the area to be repaired with etching gel, &
clean off.
Silanize the ceramic surface with a silane component.
Apply metal bonding component over exposed
metal surfaces.
Apply bonding resin to the entire area
Repair the restoration with composite component &
cure.

SHRINK-FREE CERAMIC
Ralph B.Sozio ,and Edwin j.Riley: THE SHRINK-FREE CERAMIC CROWN:J
Prosthet Dent ,February 1983,volume 49, number 2(182-187)
The alumina ceramic used in this technique (Cerestore Non-shrink
Alumina Ceramic,Coors Biomedical Co., Lakewood, Colo.)
is a shrink-free composition unlike conventional ceramic bodies,
which undergo considerable shrinkage when fired .
INDICATIONS AND CONTRAINDICATIONS
•Indicated in situations where the ceramometal restoration with
porcelain occlusal or the traditional porcelain crown are the
treatment selection.
•effectively used as both anterior and posterior restorations
•contraindicated when there is inadequate thickness,
i.e. less than 1.3 mm.

ADVANTAGES:
 Excellent fit generated by direct molding.
 Excellent esthetics aided by light transmission and lack
of metal.
 Absence of distortion with the veneer application.
 Ease of formation.
• Ease of adjustment in green
state
• Low thermal conductivity.
•Radio density similar to that of
natural enamel.

CAD – CAM CERAMICS
In this system ,the internal surface of inlays,onlays,or crowns is
ground with diamond disks to the dimensions obtained from a
scanned image of the preparation.The translational movements of the
disk is guided by computer-controlled input.
DISADVANTAGES
• need for costly equipment,
• lack of computer-controlled processing support for occlusal
adjustment
• technique sensitive nature of surface imaging required for preparing
teeth.

CEREC SYSTEM
The Cerec system has been marketed for several years with the
improved Cerec 2 system introduced in the mid-1990s.The equipment
consists of a computer integrated imaging and milling system, with
the restorations designed on the computer screen. At least three
materials can be used with this system: Vita Mark II, Dicor MGC, ++
and ProCod. δδ Vita Mark II contains sanidine (KAISiO) as a major
crystalline phase within a glassy matrix. Dicor MGC us a mica -based
machinable glass-ceramic that contains 70 volume percent of
crystalline phase. The unique “house of cards” microstructure found
in Dicor MGC is due to the interlocking of the small platelet-shaped
mica crystals with an average size of 1 to 2 um.

This particular microstructure leads to multiple crack
deflections and ensures a greater FRACTURE
RESISTANCE than leucite-containing ceramics.
ProCod is a leucite-containing ceramic designed for
making machined restorations. Weaknesses of the
earlier Cerec system include the poor marginal fit of
the restorations. And the lack of sophistication in the
machining of the occlusal surface. The marginal
adaptation of Cerce 2 is improved, and the occlusal
anatomy can be shaped.

ADVANTAGES
 negligible porosity levels
 freedom of making an impression
 reduced assistant time assosiatd with impression
procedures
 the need for only a single patient appointment
 Good patient acceptance.one can select a core
ceramic either for strength and fracture resistance,for
low abrasiveness,or for transucency.

CERCON AND LAVA ZIRCONIA CORE
CERAMICS
The material that has the greatest potential fracture toughness and
flexural strength is pure tetragonal stabilized zirconia.
The zirconia coping or framework is placed in a Cercon furnace and
fired at 1350C for 6 hrs to fully sinter the yttria-sabilized zirconia core
coping or framework.
The ssintering shrinkage is achieved uniformly and linearly in the
three dimensional space by the integrated process of
scanning,enlarging the pattern design,controlled milling ,and
sintering. After subsequent trimming with a water cooled ,high speed
diamond bur , the finished ceramic core framework is then veneered
with a veneering ceramic and stain ceramic.

ABRASIVENESS OF DENTAL CERAMICS
Ceramics are generally considered the most
biocompatible durable and aesthetic materials
available for rehabilitation of teeth occlusal function
and facial appearance. In spite of their overall
excellence in meeting the ideal requirements of a
prosthetic material, dental ceramics have one major
drawback. These materials can cause catastrophic
wear of opposing tooth structure under certain
conditions. The most extreme damage occurs when a
roughened surface contacts tooth enamel or dentin
under high occlusal forces, which may occur because
of bruxing premature occlusal contacts, and/or
inadequate occlusal adjustments.

Abrasive wear mechanisms for dental restorative materials and
tooth enamel include
(1) adhesion (metals and composites), in which localized
bonding of two surfaces occurs, resulting in pullout and transfer
of matter from one surface to the other, and
 (2) microfracture (ceramics and enamel), which results from
gouging asperities, impact, and contact stresses that cause
cracks or localized fracture.
The microfracture mechanism is the dominant mechanism
responsible for surface breakdown of ceramic and the
subsequent damage that a roughened ceramic surface can cause
to tooth enamel surfaces.

Enamel is also susceptible to this kind of microfracture through
four specific mechanisms :
(1) asperities extending from the ceramic surface that produce
high localized stress and mircofracture;
(2) gouging that results from high stresses and large hardness
differences between two surfaces or particles extending from
these surfaces;
(3) impact or erosion that occurs through the action of abrasive
particles carried in a flowing liquid such as saliva; and
(4) contact stress microfracture that increases localized tensile
stress and also enhances the damage caused by asperities,
gouging, and impact or erosion.

Reducing abrasiveness of ceramics
by polishing and glazing
Jagger and Harrison (1994) reported that the amount of
enamel wear produced by both glazed (28.8 micro m) and
unglazed Vitadur N aluminous porcelain (29 micro m) was
similar; however, the wear produced by polished porcelain
(12 micro m) was substantially less. Polished or glazed
porcelain caused significantly less wear than unglazed
porcelain. Polishing was accomplished with 3 M Soflex disks
and Shofu rubber points.
Hulterstrom and Bergman (1993) found that two of the best
polishing systems are Sof-Lex (3M Dental) and Shofu
Porcelain Laminate Polishing kit followed by diamond
paste.

Guidelines for minimizing excessive wear of
enamel by dental ceramics
To minimize the wear of enamel by dental ceramics,the
following steps should be taken:
Ensure cuspid-guided disocclusion
Eliminate occlusal prematurities
Use metal in functional bruxing areas
If occlusion in ceramic ,use ultralow fusing ceramics
Polish functional ceramic surfaces
Repolish ceramic surfaces periodically
Readjust occlusion periodically if needed

CRITERIA FOR SELECTION OF DENTAL CERAMICSCRITERIA FOR SELECTION OF DENTAL CERAMICS
1. The dentist should not use all-ceramic crowns for patients
with evidence of extreme bruxism, clenching,
or malocclusion. In this case, metal-ceramic or all
metal prostheses should be used.
2. The experience of the laboratory technician should
be extensive to ensure a success rate of at least 98% over a
3-year period.
3. The dentist should judge whether previous aesthetic success
with metal-ceramic prostheses combined with the aesthetic
demands of the specific patients would yield more
predictable outcomes and longevity than an all ceramic crown.
4. Use all-ceramic crowns when adjacent anterior teeth exhibit a
high degree of translucency. Ceramic systems are useful for
matching adjacent tooth shades for young patients

5. Patients must accept the described benefits, risks, and alternatives to
the proposed treatment, and they must give their consent for the
treatment to be performed .The initial cost and the expenses
associated with remakes for the ceramic crowns will be higher than
those associated with metal-ceramic crowns.
6. Some ceramic crowns will not be aesthetic if the tooth
preparations are inadequate, particularly when
insufficient tooth structure has been removed .
Patients with shorter crown height should not be treated
with ceramic FPDs because inadequate connector for
height will increase the risk for connector fracture.
7. The skill of the dentist is of paramount importance in
producing perfect impressions derived from smooth
preparations free of undercuts with continuous,
well-defined margins and with adequate tooth reduction.

JOURNAL OF ORAL REHABILITATION 2003
Fracture reasons in ceramic-fused-to-metal
restorations
M. O¨ ZCAN
SUMMARY
Fracture of the ceramic veneers as a result of oral function or
trauma is not an uncommon problem in clinical practice .
Fractures in the anterior region pose an aesthetic problem, but
when they are in the posterior, chewing function could also be
affected. The published literature reveals that reasons for
failures cover a wide spectrum from iatrogenic factors to
laboratory mistakes or because of factors related to the
inherent structure of the ceramics or simply to trauma.

JADA, VOL. 137 APRIL 2006
Fracture resistance of different partial-coverage
ceramic molar restorations
Christian F.J. Stappert,
Within the limits of this investigation, we can conclude
the following:
All-ceramic PCRs for molars made of IPS e.max Press are
fracture-resistant, showing results comparable with those
of natural unprepared teeth.A defect-oriented tooth
preparation in the posterior region for the restoration of a
compromised tooth with a partial-coverage ceramic
restoration is justifiable.

JADA, VOL. 136 NOVEMBER 2005
A simplified rubber-dam technique for preparing
teeth for indirect restorations
GRANT A. PERRINE
The slit–rubber-dam technique involves the use of a
common dental armamentarium to simplify the
preparatory phase of indirect restorative procedures. The
slit dam enhances visibility enables the practitioner to
retract and protect the soft tissues, helps prevent the
patient from swallowing or aspirating the tooth or
restorative materials, controls oral fluids and promotes
operating efficiency. This simple technique considerably
reduces the stress for the dentist, dental assistant and
patient.

JOURNAL OF
PROSTHODONTICS,VOL16,NO3(MAY-
JUNE),2007
Effect of Water Storage and Surface Treatments on
the Tensile Bond Strength of IPS Empress 2
Ceramic
LucianaA.Salvio,
Conclusions:
Storage time significantly decreased the tensile bond
strength for both ceramic surface treatments. The
application of 10% hydrofluoric acid resulted in
stronger tensile bond strength values than those
achieved with aluminum oxide.

JOURNALOFPROSTHODONTICS,VOL14,NO4(D
ECEMBER),2005
Comparison of Bond Strength of a Pressed
Ceramic Fused to Metal versus Feldspathic
Porcelain Fused to Metal
DanielM.Schweitzer,DDS;
Conclusion:
The debonding/crack initiation strength of a low-
fusing pressable leucite-based glass ceramic
fused to metal was equivalent to that of a
feldspathic porcelain fused to metal.

J PROSTHOD 1994
In Vitro Fracture Behavior of Ceramic and Metal-
Ceramic Restorations
Thomas B. Smith, Ohn A
Conclusions:
Failure for both restorative systems involved interfacial
stresses with crack propagation occurring at or near
the core-veneer interface. The weaker interface in the
Metal- ceramic system probably resulted from an
increase in surface oxide volume. For the ceramic
crowns, delamination crack fronts appeared to propagate
through chemically unaltered veneering porcelain.

International Association for Dental Research (June 25-28,
2003)
In vitro Fracture Strength of Teeth Restored with
Different Procera All-ceramic Crowns
Conclusions:
Alumina, zirconia, and metal copings offer the same fracture
resistance for teeth restored with resin-bonded all-ceramic or
porcelain-fused-to-metal crowns.

International Association for Dental Research (June 25-28,
2003)
Marginal Fit of a
Low-fusing Pressable Leucite Glass Ceramic in Full
Crowns and
Ceramic-pressed-to-Metal Crowns
N.W. BOYD, G.R. GOLDSTEIN
Conclusion:
The marginal fit of the PCCs and the PTMs were similar to
conventional PFMs.

International Association for Dental Research (June
25-28, 2003)
Comparison of Tensile Bond Strength of a Pressed
Ceramic to Metal vs. Feldspathic Porcelain Fused to
Metal
G.R. GOLDSTEIN, N.R.F.A. DA SILVA,
Conclusion:
The TBS of a low fusing pressable leucite glass ceramic was
equivalent to that of a feldspathic porcelain fused to metal.

25-28, 2003)
Effect of Sodium Content on the Mechanical
Properties of Glass-ceramics
I.DENRY,
Conclusion:
The crystalline phase combination was optimum with 1.9 wt%
sodium, leading to the highest apparent fracture toughness.

25-28, 2003)
Effect of Ion Exchange on Flexural Strength of
Feldspathic Porcelains
N. JUNTAVEE
Conclusions:
The study indicated that flexural strength of porcelain was
treatment is enhanced by ion treatments, except for Li+
ion
process. The Li+
-Rb+
ion the most effective technique.

25-28, 2003)
Fracture Strength of Composite and All-
ceramic CAD-CAM Crowns
Conclusions:
Cyclic loading fatigue reduced the fracture strengths
of composite and all-ceramic crowns, while adhesive
cementation increased the fracture strengths.

J Prosthod 1995;4: 101- 110
A Comaprison of Infrared and Torch soldering of Au-Pd and
Co-Cr Metal-Ceramic Alloys Using a High-Fusing Solder
ohn T. Dominici, DDS, MS
Conclusions: Although the two heating methods produced
solder joints that had strengths that were not significantly
different, infrared-heated joints showed less scatter in bond
strengths. It was suggested that, in the hands of most
technicians, fewer infrared-heated joints would contain
defects visible at a magnification of 40x. The presence of
such defects may increase the probability of in vivo failure
caused by cyclic stresses.

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