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ALLOYS FOR PFM

INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

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ADA CLASSIFICATION
• In 1984 ADA given classification of alloys that
are used for the metal ceramic restorations.
• They a...
HIGH NOBLE ALLOY
SYSTEMS.
•
•
•

Au-Pt-Pd.
Au-Pd-Ag.
Au-Pd.

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DIFFERENT ALLOY SYSTEMS
THEIR ADVANTAGES
&DISADVANTAGES

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Au-Pt-Pd

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COMPOSITION:Gold:75%-88%
Platinum:-8%
Palladium:-11%
Silver:-5%
Trace elements of indium,iron,&tin are
used for the porcel...
PALLADIUM:•Palladium added to increase the corrosion,
strength,hardness,tarnish resistance of the gold based
alloys.
•It i...
•SILVER:•It lowers the melting range,improves the
fluidity,&helps to control the CTE.
•It has high affinity for the oxygen...
Au-Pt-Pd
• Advantages
• Excellent
castability&porcelain
bonding
• Easy to adjust &finish
• Tarnish&corrosion
resistance
• ...
•GOLD:-it provides the high levels of the tarnish
&corrosion.
•It increases melting range.
•It improves the wettability,bu...
Au-Pd-Ag
Composition:Gold:39%-53%
Palladium:25%-35%
Silver:12%-22%

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• Advantages
• Disadvantages
• Less expensive
• Silver content creates
potential for porcelain
• Improved rigidity&sag
dis...
GOLD-PALLADIUM ALLOY SYSTEMS
Gold:44%-55%
Palladium:35%-45%
Gallium:5%
Indium & tin:8%-12%

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AdvantagesDisadvantages
•
•
•
•
•

Excellent castability
Good bond strength
Corrosion & tarnish
Improved hardness &
streng...
NOBLE ALLOY SYSTEMS
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•
•
•
•
•
•

Pd-Au.
Pd-Au-Ag.
Pd-Ag.
Pd-Cu.
Pd-Co.
Pd-Ga-Ag

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PALLADIUM – SILVER ALLOY SYSTEM
Composition:
Palladium:55%-60%
Silver:28%-30%
Indium & tin are used.

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• PALLADIUM:-- palladium is added to increase
the strength, hardness, corrosion&tarnish
resistance.
• It elevates the allo...
• TIN:-

• Tin is the hardening agent that acts as a lower
melting range of the of an alloy.
• It also assists in oxide la...
• Advantages
• Low cost & density
• Good castability &
porcelain bonding
• Low hardness
• Excellent sag ,tarnish
& corrosi...
PALLADIUM-COBALT
•
•
•
•
•

composition:
palladium78%-88%.
cobalt 4%-10%
trace elements of
gallium,indium are used.

www.i...
• Cobalt is used for alternative of the nickel
based alloys, but the cobalt based alloys are
difficult to process.]
• Coba...
•
•
•
•

Advantages.
Low cost
Good sag resistance
Good
castability,polishabiliy
• Easier to solder

• Disadvantages
• Comp...
PALLADIUM-COPPER
•
•
•
•

palladium 70-80%
copper 9-15%
gold 1-2%
platinum 1-2%

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•
•
•
•

COPPER:Copper serves as hardening agent.
Lowers the melting range of alloy.
It helps to form an oxide layer for p...
•
•
•
•

Advantages.
Good castability.
Low cost than gold.
Good tarnish and
corrosion resistant.
• Compatible with
dental ...
Pg-Ag-Au
•
•
•
•

composition:
palladium 75-86%
silver
1-7%
gold
less than 1%

• Trace amounts of indium & gallium are
fou...
•
•
•
•

Advantages
Low cost
Low density
Improved sag
resistance.
• Light colored oxide
layer.

• Relatively new alloy
gro...
•
•
•
•
•

INDIUM:Lowers the melting range of the alloy.
It improves the fluidity.
It has strengthening effect.
It is adde...
• GALLIUM:
• It is added to the silver free porcelains to
compensate for the decreased CTE created by
silver removal.

www...
PREDOMINANTLY BASE
METAL ALLOYS
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•
•
•

Ni-Cr-Mo-Be
Ni-Cr-Mo
Co-Cr-Mo

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NICKEL-CHROMIUM-MOLYBDENUMBERYLLIUM ALLOYS
COMPOSITION:
Nickel:62%-82%
Chromium:11-20%
Beryllium:2%

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•NICKEL:-it is base for the porcelain alloys.
•Its CTE similar to the gold
•It provides resistance to corrosion.

BERYLLIU...
• Aluminum:-lowers the melting range of the
nickel based alloys.
• It acts as a hardening agent.
• It influences the oxide...
• IRON:-

• Iron is added to some gold based porcelain for
hardening & oxide production.

SILICON:•Silicon primarily as an...
•
•
•
•
•

Advantages
Low cost
Low density
High resistance
It can produce thin
castings
• Poor thermal
conductor
• Can be ...
NICKEL-CHROMIUM ALLOYS
Composition:
Nickel :62%-77%
Chromium :-11%-22%

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CHROMIUM:•Chromium is a solid solution
hardening agent that contributes to
corrosion resistance.

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BORON:Boron is a de oxidizer.
It reduces the surface tension there by
increases the castability.
Reduce the ductility & in...
• Do not contain
beryllium
• Low cost
• Low density means
more castings per
ounce.

• Disadvantages
• Cannot be use with
n...
COBALT – CHROMIUM ALLOYS
Composition:
Cobalt:53%-68%
Chromium:25%-34%
Trace elements of molybdenum ruthenium are
added.
ww...
CHROMIUM:• Chromium is a solid solution hardening agent
that contributes to corrosion resistance.
• COBALT:-used as altern...
• Molybdenum improves corrosion
resistance,influences the oxide layer,helpful in
adjusting CTE in nickel based alloys.

ww...
•
RUTHENIUM:
• It acts as a grain refiner.
• It improves the tarnish resistance.

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• Advantages
• Do not contain nickel
• Do not contain
beryllium
• Poor thermal
conductors
• Low density
• Low cost

• Disa...
SOLDERING.
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• SOLDERING:-A group of process that join
metal by heating them to a suitable temperature
below the solidus of the substra...
• BRAZING:The process of joining metals above
450 degree centigrade.
• WELDING:-The joining of two or more metal
pieces by...
SOLDERING OF FIXED
PARTIAL DENTURES.
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PHYSICAL REQUIREMENTS OF
SOLDER MATERIALS
• Resistance to tarnish & corrosion.
• Fusion temperature 90-180 degree Fahrenhe...
SOLDERING FLUXES

• Flux is Latin word means flow.Dental do not
flow or wet the metallic surfaces that have an
oxide layer...
•

ANTI FLUX

• Anti flux is a material that is used to confine the
flow of the molten solder over the metals being
joined...
Fundamental considerations
• Position accurately the uncontaminated parts to
be joined.
• Determine the solder gaps and co...
• ARMAMENTAIRUM

•
•
•
•
•
•
•
•
•
•

Plaster bowl & spatula
Impression plaster.
Bite registration paste.
Index tray or to...
•
•
•
•
•

Fisher burner & matches.
Tripod screen.
Solder
Blow pipe.
Tooth brush.

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• Remove the provisional restoration from the
patient’s mouth make certain that there are no
temporary cement left on the ...
• Mix a small amount of
fast setting impression
plaster & place it on
plastic index tray or
thoroughly wet tongue
depresso...
1. Place the tray in
the mouth over
the castings.once
the plaster set,
remove the
template and
check for the
accuracy
www....
• Trim the excess plaster
so that after seating
the template, it is
possible to cover their
margins with soldering
investm...
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• A strip of boxing wax
2.5mm thick wide
wrapped around the
index.

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• Mix the soldering
investment according
to the manufacturer
instructions.completel
y fill the interior of the
retainer ca...
• Remove the plaster
template & trim the
investment so, that
soldering model
allows the ready
access of heat to the
joint ...
• Heat the soldering
model sufficiently to
vaporize wax
remaining in the joint.

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• While the joint is still
warm coat the solder
with flux and place the
solder in the place.

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• Reheat the soldering model until the solder
flows.
• Remove the flame, apply bluish flame in circular
manner around the ...
POST VENERING SOLDERING
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• Try in the units in the mouth & make necessary
adjustments.

• Remove the FPD from the mouth,cut the joint
using disk.

...
• Making the plaster
index.

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• Cyanoacrylate liquid
resin is squeezed onto
the joint space.

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• To prevent investment
form contaminating
the ceramic place
1.0mm thick ivory
wax over gingival one
half to 2/3rd of the
...
• Mix a small amount of
the soldering
investment and
carefully vibrate into
the crowns.

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• Soldering investment
is placed over the flat
surface.

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• Put the FPD into the
investment.

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• Investment is pushed
over the lingual
surfaces of the FPD

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• The investment is
trimmed leaving
3.0mm around the
castings. The entire
block is beveled.

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• A V shaped notch
is placed over the
lingual surface.

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• The wax layer
separates the
investment and
porcelain.

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• After the wax
removal, a space
between porcelain and
investment protects
the porcelain.

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MECHANISM OF PORCELAIN
–METAL ATTACHMENT
• Four theories have been proposed to
explain the processes that lead to
porcelai...
VAN DER WAALS FORCES.
1. The attraction between charged atoms that are in
intimate contact yet do not actually exchange
el...
4. It is also believed that bonding entails some
measure of true adhesion based on the extent
to which the metal substruct...
7. A rough, contaminated metal surface will
inhibit wetting and reduce the vanderwaals
bond strength. On the other hand, a...
MECHANICAL RETENTION:
• 1. The porcelain-bearing area of a metal
casting contains many microscopic
irregularities into whi...
3. Despite it’s presence, mechanical retention’s
contribution to bonding may be relatively
limited.
4. Dental porcelain do...
COMPRESSION BONDING
• Dental porcelain is strongest under
compression and weakest under tension.
• Hence , if the coeffici...
• 2. This difference in contraction rates
creates tensile forces on the metal and
corresponding compressive forces on the
...
THERMAL EXPANSION
• Generally substances increase in the length
and volume when they are heated. This
phenomenon is called...
RELATION BETWEEN METAL AND
PORCELAIN
• When porcelain is fused to metal, three
possible relations can exist in thermal
exp...
THERMAL EXPANSION IS GREATER IN
PORCELAIN THAN IN METAL.
• Greater thermal expansion in porcelain means
that during the ti...
• Hence porcelain becomes shorter after cooling
although they had the same length before
heating.
• In the ceramo-metallic...
THERMAL EXPANSION IS EQUAL
BETWEEN METAL AND PORCELAIN
• As metal and porcelain expand or contract at
the same rate, there...
THERMAL EXPANSION IS GREATER
IN METAL THAN IN PORCELAIN.
• In general, this thermal expansion
relationship exists between ...
• However, this does not mean that cracking
will never occur.
• If there is a significant difference in thermal
expansion ...
CHEMICAL BONDING
• The single most significant mechanism of
porcelain-metal attachment is a chemical bond
between dental p...
• The oxide layer itself is sandwiched in
between the metal substructure and the
opaque porcelain.
• This sandwich theory ...
• From a chemical standpoint, both covalent
and ionic bonds are thought to form but
only a monomolecular( single) layer of...
PORCELAIN METAL BOND FAILURES
• Metal ceramic alloys, whether noble or base
metals, all oxidize differently because of
var...
PORCELAIN DELAMINATION

• With base metal alloys, the separation of
porcelain veneer from the metal sub structure
can be m...
• In some instance bond failure may not be due to
chemical bond failure.in contrarary,it may be due
to too thick of the ox...
INCOMPITENT MATERIALS
• Bond failure may occur due to physical
incompatibility between porcelain and metal.

• The differe...
OVER OXIDATION/UNDER
OXIDATION
• The oxidation procedure varies for alloys of
different compositions.so the process it sel...
• Over oxidation or under oxidation should be
reprocessed accordingly until uniform oxide of
desired color and thickness r...
CONTAMINATION
• That that are demonstrated some form of
contamination may not have to be remade.
• Simple finishing, a sub...
•
•
•
•
•
•
•
•

POCELAIN APPLICATION
METHODS

INSTRUMENTS AND EQIUPMENTS:
Brushes
Carving instruments
Spatula
Razor knife...
PORCELAIN FURNACE
•
•
•
•
•

Three types of the furnaces are available:
Manual.
Automatic.
Programmable.
There certain fut...
• In the event the vacuum does not reach an
adequate level, or if the firing chamber does not
properly seal, resulting in ...
• Most furnaces can also be set to hold the work at
a temperature for a a specified length of time as
determined by case b...
• Furnaces in the second category have a vertical
entry in to the muffle. With the vertical loading
design,the muffle flat...
PORCELAIN CONDENSATION
• Capillary action.
• Vibration.
• Spatulation.
• Whipping.
• Dry powder addition.
www.indiandental...
CAPILLARY ACTION
• The technique of bottling a wet build up with
absorbent paper uses surface tension to with draw
liquid ...
• An overly aggressive technique could dislodge
the porcelain buildup form underlying metal sub
structure.

www.indiandent...
VIBRATION
• The easiest and simplest form of vibration created
by passing serrated instrument over the neck of
the hemosta...
• There several devices to provide mechanical
vibration such as, vibrating brushes, spatulas,and
ultrasonic condensers.
• ...
SPATULATION
• With this form of condensation,a spatula or
porcelain carver is used to apply,rub the
porcelain buildup to f...
WHIPPING

• This method actually be nothing more than
variation of vibration technique.

• As the porcelain built up, a no...
DRY POWDWER ADDITION:

• This method is less widely used.
• This technique also referred as brush application
method.
• Dr...
POCELAIN APPLICATION
METHODS.
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OPAQUE PORCELIAN
APPLICATION.
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GLASS ROD TECHNIQUE
•

First, lightly wet the
oxidized metal metal substructure to
be veneered with distilled water and ge...
• Use point end of glass
rod to apply the
opaque
porcelain.begin the
opaquing most convex
portion of the metal.

www.india...
• Move the opaque
towards the porcelain
metal junction from
one inter proximal
area to to other &
cover the incisal area.
...
• Lightly tap the
hemostat with metal
instrument to
condense the opaque
porcelain and excess
opaquing liquid will
raise to...
• Place the edge of
tissue,against the an
edge of the moist
opaque porcelain.hold
the tissue in place until
the liquid is ...
• Blend the opaque at
the porcelain metal
junction to establish a
gradual transition from
opaque to external
surface.

www...
BRUSH TECHNIQUE

• Opaque can also be
applied with the
brush.load the brush
tip with opaque
porcelain and carry it
to the ...
• Application of the
opaque twice is also
recommended.initially
thin layer of the
opaque and complete
masking is followed....
DENTIN APPLICATION
METHOD.
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• Carefully return the
cleaned,opaqued
coping to the master
cast.place folded
tissue or bottling paper
on the lingual side...
• To minimize the
potential for entrapping
air in the porcelain,
move the tip of the
pointed brush through
the mixed denti...
• Apply the porcelain to
the most convex area
on the restoration.

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• Gently push the
porcelain to the
intrproximal,incisal
areas.

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• Move the porcelain
down to the incisal
edge and lightly blot
the build up to
condense the porcelain
on the substructure....
• To create the mesialfacial line angle,wipe
the brush to dry it
slightly and reduce the
pointing then lightly
move from t...
• Point the brush and
add additional dentin
porcelain to lingual
aspect of the incisal
edge.smooth and
condense the incisa...
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• Use a razor knife to
cut back the incisal
edge from between
1.0to1.5mm

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• Remove dentin
porcelain at the mesial
inter proximal line
angle.extend the cut to
the junction of the
middle and gingiva...
• At the distal
intrproximal line
angle,make a cut form
the incisal edge
towards the gingival
1/3rd as far as required
for...
• Examine the
restoration from an
incisal view for
symmetry and
adequacy of the cut
back.

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ENAMEL APPLIACTION
METHODS.
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• With pointed
brush,apply enamel
porcelain to one
corner of cutback.

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• Add more enamel
porcelain and move it
across the facial
surface in the incisal
one third.

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• Blend the enamel
porcelain at the
junction of middle and
gingival 1/3rd &begin
to establish the incisal
edge & condense ...
• Blend the enamel
porcelain into gingival
1/3rd on the facial
surface.Recreate the
interproximal contours
and line angles...
• Shape the mesialincisal corner as
required for each
case.examine the
build up form incisal
view&evaluate the
overall sha...
ALTERNATIVE BUILD UP
TECHNIQUE.
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• Apply the opaque to
mask the underlying
metal.

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• Complete & smooth
the dentin buildup.

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• Create three
developmental lobes
with the pointed brush.

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• Invert the cast & place
translucent porcelain
in the two
developmental
groove.apply enamel
porcelain to the inter
proxim...
• Continue this process
until the entire crown
is built to full contour.

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• Finally, use the
whipping brush to
gently smooth the
entire porcelain build
up.

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• Once the porcelain has
been fired,you should
be able to observe
demonstrable
mamelons in the
restoration.

www.indianden...
PORCELAIN APLICATION FOR
FIXED PARTIAL DENTURE.
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• Apply and condense
opaque
porcelain.Cover any
gray areas,and fire the
prosthesis.

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• Return the opaqued
FPD to the master cast
with a piece of tissue
paper cut to cover the
entire pontic area.

www.indiand...
• Add a small portion of
dentin porcelain to the
under side of the
pontic on the FPD
frame work.

www.indiandentalacademy....
• Return the frame work to
the master cast and gently
rock it back and forth
until it seats
completely.Remove the
frame wo...
• Place the frame work
back on the master
cast and apply dentin
porcelain or add and
condense opacous
dentin to the cervic...
• Complete the dentin
build up.

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• Create the
developmental
lobes.Use thin razor
knife to cut through
inter proximal areas
and individualize the
teeth.

ww...
• Add enamel veneering
material.

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• Condense the
porcelain build up.

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• Measure the mesialdistal width of each
tooth with a Boley
gauge.compare that
measurement with
porcelain build up.

www.i...
• Use a knife or other
instrument to make
any necessary
adjustments in the
mesial-distal width.

www.indiandentalacademy.c...
• Facial view of the
build up.

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• Lingual view of the
build up.

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• Three unit FPD after
firing.

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FIRING PROCEDURES.
• The large bulk of the build up will require more
time to dry and pre heat than the opaque
porcelain.
...
• Restorations that are under fired porcelain often
have to be stripped form metal and rebuilt.
• Over fired porcelains ap...
Thank you
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Leader in continuing dental education

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Alloys for pfm crown &bridg /certified fixed orthodontic courses by Indian dental academy

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Alloys for pfm crown &bridg /certified fixed orthodontic courses by Indian dental academy

  1. 1. ALLOYS FOR PFM INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. ADA CLASSIFICATION • In 1984 ADA given classification of alloys that are used for the metal ceramic restorations. • They are classified as, • High noble. • Noble. • Predominantly base metal. www.indiandentalacademy.com
  3. 3. HIGH NOBLE ALLOY SYSTEMS. • • • Au-Pt-Pd. Au-Pd-Ag. Au-Pd. www.indiandentalacademy.com
  4. 4. DIFFERENT ALLOY SYSTEMS THEIR ADVANTAGES &DISADVANTAGES www.indiandentalacademy.com
  5. 5. Au-Pt-Pd www.indiandentalacademy.com
  6. 6. COMPOSITION:Gold:75%-88% Platinum:-8% Palladium:-11% Silver:-5% Trace elements of indium,iron,&tin are used for the porcelain bonding. www.indiandentalacademy.com
  7. 7. PALLADIUM:•Palladium added to increase the corrosion, strength,hardness,tarnish resistance of the gold based alloys. •It increases the melting temperature. •Improves the sag resistance. •PLATINUM:-It increases the strength,hardness,of the gold based alloys. •It improves the corrosion,tarnish &sag resistance. •It improves the density of the gold non gold based alloys. www.indiandentalacademy.com
  8. 8. •SILVER:•It lowers the melting range,improves the fluidity,&helps to control the CTE. •It has high affinity for the oxygen, which can lead to the porosity&gassing of the casting. •It is not universally regarded as noble in the oral cavity. www.indiandentalacademy.com
  9. 9. Au-Pt-Pd • Advantages • Excellent castability&porcelain bonding • Easy to adjust &finish • Tarnish&corrosion resistance • Biocompatible • Not technique sensitive • • • • • disadvantages Poor sag resistance Low hardness Low density High cost www.indiandentalacademy.com
  10. 10. •GOLD:-it provides the high levels of the tarnish &corrosion. •It increases melting range. •It improves the wettability,burnishability &increases the density. www.indiandentalacademy.com
  11. 11. Au-Pd-Ag Composition:Gold:39%-53% Palladium:25%-35% Silver:12%-22% www.indiandentalacademy.com
  12. 12. • Advantages • Disadvantages • Less expensive • Silver content creates potential for porcelain • Improved rigidity&sag discoloration. resistance • High cost • High nobility level • High CTE • Tarnish &corrosion resistance www.indiandentalacademy.com
  13. 13. GOLD-PALLADIUM ALLOY SYSTEMS Gold:44%-55% Palladium:35%-45% Gallium:5% Indium & tin:8%-12% www.indiandentalacademy.com
  14. 14. AdvantagesDisadvantages • • • • • Excellent castability Good bond strength Corrosion & tarnish Improved hardness & strength • Low density. • Not thermally compatible with expansion • High cost www.indiandentalacademy.com
  15. 15. NOBLE ALLOY SYSTEMS www.indiandentalacademy.com
  16. 16. • • • • • • Pd-Au. Pd-Au-Ag. Pd-Ag. Pd-Cu. Pd-Co. Pd-Ga-Ag www.indiandentalacademy.com
  17. 17. PALLADIUM – SILVER ALLOY SYSTEM Composition: Palladium:55%-60% Silver:28%-30% Indium & tin are used. www.indiandentalacademy.com
  18. 18. • PALLADIUM:-- palladium is added to increase the strength, hardness, corrosion&tarnish resistance. • It elevates the alloy’s melting temperature. • It improves the sag resistance. • Palladium possess the a high affinity for the hydrogen,oxygen& carbon. • It lowers the density of the gold based alloys. www.indiandentalacademy.com
  19. 19. • TIN:- • Tin is the hardening agent that acts as a lower melting range of the of an alloy. • It also assists in oxide layer production for the porcelain bonding in gold based & palladium based alloys. • Tin is the one of the key trace elements for the oxidation of the palladium silver alloys. www.indiandentalacademy.com
  20. 20. • Advantages • Low cost & density • Good castability & porcelain bonding • Low hardness • Excellent sag ,tarnish & corrosion resistance • Suitable for long span fpd’s • Disadvantages • Discoloration • Pd-Ag prone to absorb gases • High CTE • May form internal oxides. • Should not be cast in carbon crucible www.indiandentalacademy.com
  21. 21. PALLADIUM-COBALT • • • • • composition: palladium78%-88%. cobalt 4%-10% trace elements of gallium,indium are used. www.indiandentalacademy.com
  22. 22. • Cobalt is used for alternative of the nickel based alloys, but the cobalt based alloys are difficult to process.] • Cobalt is added to in palladium alloys to increase the CTE,& acts as a strengthener. www.indiandentalacademy.com
  23. 23. • • • • Advantages. Low cost Good sag resistance Good castability,polishabiliy • Easier to solder • Disadvantages • Compatible with high expansion porcelains. • Produce a thick,dark.oxide colored layer may cause bluing of the porcelain. • More prone to gas absorption. www.indiandentalacademy.com
  24. 24. PALLADIUM-COPPER • • • • palladium 70-80% copper 9-15% gold 1-2% platinum 1-2% www.indiandentalacademy.com
  25. 25. • • • • COPPER:Copper serves as hardening agent. Lowers the melting range of alloy. It helps to form an oxide layer for porcelain bonding. • It lowers the density. www.indiandentalacademy.com
  26. 26. • • • • Advantages. Good castability. Low cost than gold. Good tarnish and corrosion resistant. • Compatible with dental porcelains. • Produce dark,thick oxide layer. • May discolor some porcelains. • Should not be cast in the carbon crucibles. • Absorbs gases. • Suitable for the long span bridges. • Difficult to polish. • High hardness www.indiandentalacademy.com
  27. 27. Pg-Ag-Au • • • • composition: palladium 75-86% silver 1-7% gold less than 1% • Trace amounts of indium & gallium are found. www.indiandentalacademy.com
  28. 28. • • • • Advantages Low cost Low density Improved sag resistance. • Light colored oxide layer. • Relatively new alloy group no data on long term performances. • Prone to gaseous absorption. • Should not be cast in carbon crucibles. www.indiandentalacademy.com
  29. 29. • • • • • INDIUM:Lowers the melting range of the alloy. It improves the fluidity. It has strengthening effect. It is added to non gold based alloys to form an oxide layer. • It enhances the tarnish & corrosive resistance. www.indiandentalacademy.com
  30. 30. • GALLIUM: • It is added to the silver free porcelains to compensate for the decreased CTE created by silver removal. www.indiandentalacademy.com
  31. 31. PREDOMINANTLY BASE METAL ALLOYS www.indiandentalacademy.com
  32. 32. • • • Ni-Cr-Mo-Be Ni-Cr-Mo Co-Cr-Mo www.indiandentalacademy.com
  33. 33. NICKEL-CHROMIUM-MOLYBDENUMBERYLLIUM ALLOYS COMPOSITION: Nickel:62%-82% Chromium:11-20% Beryllium:2% www.indiandentalacademy.com
  34. 34. •NICKEL:-it is base for the porcelain alloys. •Its CTE similar to the gold •It provides resistance to corrosion. BERYLLIUM:Lowers the melting temperature of the nickel based alloys. It improves the castability,improves polish ability. Helps to control the oxide layer formation www.indiandentalacademy.com
  35. 35. • Aluminum:-lowers the melting range of the nickel based alloys. • It acts as a hardening agent. • It influences the oxide layer formation. • With cobalt chromium alloys used for the metal ceramic restoration, aluminum is the on of the element that is etched from the alloy surface to create micro mechanical retention for resin bonded retainers. www.indiandentalacademy.com
  36. 36. • IRON:- • Iron is added to some gold based porcelain for hardening & oxide production. SILICON:•Silicon primarily as an oxide scavenger. •It also act as a hardening agent. www.indiandentalacademy.com
  37. 37. • • • • • Advantages Low cost Low density High resistance It can produce thin castings • Poor thermal conductor • Can be etched. • Disadvantages • Cannot be used with Ni sensitive patients • Beryllium may be toxic to the technician & patients • Bond failure may occur • High hardness • Difficult to solder • Difficult to cut through cemented castings www.indiandentalacademy.com
  38. 38. NICKEL-CHROMIUM ALLOYS Composition: Nickel :62%-77% Chromium :-11%-22% www.indiandentalacademy.com
  39. 39. CHROMIUM:•Chromium is a solid solution hardening agent that contributes to corrosion resistance. www.indiandentalacademy.com
  40. 40. BORON:Boron is a de oxidizer. It reduces the surface tension there by increases the castability. Reduce the ductility & increase the hardness. www.indiandentalacademy.com
  41. 41. • Do not contain beryllium • Low cost • Low density means more castings per ounce. • Disadvantages • Cannot be use with nickel sensitive patients • Produce more oxides than Ni-Cr-Be alloys. • May not cast as well as Ni-Cr-Be alloys www.indiandentalacademy.com
  42. 42. COBALT – CHROMIUM ALLOYS Composition: Cobalt:53%-68% Chromium:25%-34% Trace elements of molybdenum ruthenium are added. www.indiandentalacademy.com
  43. 43. CHROMIUM:• Chromium is a solid solution hardening agent that contributes to corrosion resistance. • COBALT:-used as alternative to the nickel based alloys. • Cobalt included in the high palladium alloys to increase the CTE. • It also acts a strengthener. www.indiandentalacademy.com
  44. 44. • Molybdenum improves corrosion resistance,influences the oxide layer,helpful in adjusting CTE in nickel based alloys. www.indiandentalacademy.com
  45. 45. • RUTHENIUM: • It acts as a grain refiner. • It improves the tarnish resistance. www.indiandentalacademy.com
  46. 46. • Advantages • Do not contain nickel • Do not contain beryllium • Poor thermal conductors • Low density • Low cost • Disadvantages • More difficult to process than Ni base alloys • High hardness • Oxide more than both Ni based alloys • No information on long term clinical studies. www.indiandentalacademy.com
  47. 47. SOLDERING. www.indiandentalacademy.com
  48. 48. • SOLDERING:-A group of process that join metal by heating them to a suitable temperature below the solidus of the substrate metals & applying a filler metal having liquidus not exceeding 450 degree centigrade that melts and flows by capillary attraction between the parts with out appreciably affecting the dimension of joined structure. • In dentistry,many metals are joined by brazing,although,the term soldering is used. www.indiandentalacademy.com
  49. 49. • BRAZING:The process of joining metals above 450 degree centigrade. • WELDING:-The joining of two or more metal pieces by applying heat, pressure,or both with or without filler material, to produce localized union across the interface through fusion or diffusion. • SOLDERING FLUX: A material used to prevent the formation of,or to dissolve & facilitate removal of,oxides & other undesirable substances that may reduce the quality or strength of the soldered metal structure. www.indiandentalacademy.com
  50. 50. SOLDERING OF FIXED PARTIAL DENTURES. www.indiandentalacademy.com
  51. 51. PHYSICAL REQUIREMENTS OF SOLDER MATERIALS • Resistance to tarnish & corrosion. • Fusion temperature 90-180 degree Fahrenheit below the parts to be joined. • Free flowing when melted. • Resistance to pitting. • At least as strong as the parts to be joined. • Color compatible with the parts to be joined. www.indiandentalacademy.com
  52. 52. SOLDERING FLUXES • Flux is Latin word means flow.Dental do not flow or wet the metallic surfaces that have an oxide layer.The flux aid in the removal of the oxide layer so as to increase the flow of the molten solder. • In addition the flux also dissolves the impurities,prevents the oxidation of the metals. • Fluxes used commonly are: • Borax glass– 55%. • Boric acid --35% • Silica-10%. www.indiandentalacademy.com
  53. 53. • ANTI FLUX • Anti flux is a material that is used to confine the flow of the molten solder over the metals being joined. • The commonly used anti fluxes are pencil markings, graphite lines, iron rouge. www.indiandentalacademy.com
  54. 54. Fundamental considerations • Position accurately the uncontaminated parts to be joined. • Determine the solder gaps and configuration. • Place the flux and solder within the joint space. • Heat the parent metal and solder until the solder flows, filling the joint space. • Remove the heat as soon as possible. • Inspect the connection and correct f necessary. • Gap to be maintained is 0.3mm. www.indiandentalacademy.com
  55. 55. • ARMAMENTAIRUM • • • • • • • • • • Plaster bowl & spatula Impression plaster. Bite registration paste. Index tray or tongue blade. Petrolatum. Laboratory knife with no.25 blade. PKT waxing instrument no 1& 2. Straight hand piece. Soldering investment. Vibrator. www.indiandentalacademy.com
  56. 56. • • • • • Fisher burner & matches. Tripod screen. Solder Blow pipe. Tooth brush. www.indiandentalacademy.com
  57. 57. • Remove the provisional restoration from the patient’s mouth make certain that there are no temporary cement left on the tooth preparation. • Try in the single retainer first and then retainer pontic combination, verify the marginal fit • Adjust the occlusion, do not polish the casting at this stage.because polishing rouge is iron-dioxide, a specific anti flux for soldering. www.indiandentalacademy.com
  58. 58. • Mix a small amount of fast setting impression plaster & place it on plastic index tray or thoroughly wet tongue depressor. www.indiandentalacademy.com
  59. 59. 1. Place the tray in the mouth over the castings.once the plaster set, remove the template and check for the accuracy www.indiandentalacademy.com
  60. 60. • Trim the excess plaster so that after seating the template, it is possible to cover their margins with soldering investment.lute the castings with the sticky wax. www.indiandentalacademy.com
  61. 61. www.indiandentalacademy.com
  62. 62. • A strip of boxing wax 2.5mm thick wide wrapped around the index. www.indiandentalacademy.com
  63. 63. www.indiandentalacademy.com
  64. 64. • Mix the soldering investment according to the manufacturer instructions.completel y fill the interior of the retainer castings. Care to avoid burying the prosthesis in the investment. www.indiandentalacademy.com
  65. 65. • Remove the plaster template & trim the investment so, that soldering model allows the ready access of heat to the joint area. www.indiandentalacademy.com
  66. 66. • Heat the soldering model sufficiently to vaporize wax remaining in the joint. www.indiandentalacademy.com
  67. 67. • While the joint is still warm coat the solder with flux and place the solder in the place. www.indiandentalacademy.com
  68. 68. • Reheat the soldering model until the solder flows. • Remove the flame, apply bluish flame in circular manner around the solder model. • As the solder is about to flow; it slumps and loses rectangular definition. • Use only reducing portions of the flame, characterized by shiny areas on the metal directly under the flame. • Allow the prosthesis for the bench cool to heat treat the metals properly. • Try the assembled prosthesis in the mouth after finishing & polishing. www.indiandentalacademy.com
  69. 69. POST VENERING SOLDERING www.indiandentalacademy.com
  70. 70. • Try in the units in the mouth & make necessary adjustments. • Remove the FPD from the mouth,cut the joint using disk. • A soldering index is made with the quick setting plaster. www.indiandentalacademy.com
  71. 71. • Making the plaster index. www.indiandentalacademy.com
  72. 72. www.indiandentalacademy.com
  73. 73. • Cyanoacrylate liquid resin is squeezed onto the joint space. www.indiandentalacademy.com
  74. 74. • To prevent investment form contaminating the ceramic place 1.0mm thick ivory wax over gingival one half to 2/3rd of the facial surfaces of the retainer and pontic. www.indiandentalacademy.com
  75. 75. • Mix a small amount of the soldering investment and carefully vibrate into the crowns. www.indiandentalacademy.com
  76. 76. • Soldering investment is placed over the flat surface. www.indiandentalacademy.com
  77. 77. • Put the FPD into the investment. www.indiandentalacademy.com
  78. 78. • Investment is pushed over the lingual surfaces of the FPD www.indiandentalacademy.com
  79. 79. • The investment is trimmed leaving 3.0mm around the castings. The entire block is beveled. www.indiandentalacademy.com
  80. 80. • A V shaped notch is placed over the lingual surface. www.indiandentalacademy.com
  81. 81. • The wax layer separates the investment and porcelain. www.indiandentalacademy.com
  82. 82. • After the wax removal, a space between porcelain and investment protects the porcelain. www.indiandentalacademy.com
  83. 83. MECHANISM OF PORCELAIN –METAL ATTACHMENT • Four theories have been proposed to explain the processes that lead to porcelain-to-metal bonding: • 1. Van der waals forces. • 2. Mechanical retention. • 3. Compression bonding. • 4. Direct chemical bonding. www.indiandentalacademy.com
  84. 84. VAN DER WAALS FORCES. 1. The attraction between charged atoms that are in intimate contact yet do not actually exchange electrons is derived from van der waals forces. 2. These secondary forces are generated more by a physical attraction between charged particles than by an actual sharing or exchange of electrons in primary(chemical) bonding. 3. Van der waals forces are generally weak, because nearly all the positive and negative charges present in these atoms are satisfied in a single molecule. www.indiandentalacademy.com
  85. 85. 4. It is also believed that bonding entails some measure of true adhesion based on the extent to which the metal substructure is wetted by the softened dental porcelain. 5. The better the wetting of the metal surface, greater the vanderwaal’s forces. 6. Furthermore, porcelain’s adhesion to metal can be diminished or enhanced by alterations in the surface characters(texture) of the porcelain-bearing surface on the substructure. www.indiandentalacademy.com
  86. 86. 7. A rough, contaminated metal surface will inhibit wetting and reduce the vanderwaals bond strength. On the other hand, a slightly textured surface, created by finishing with uncontaminated aluminum oxide abrasives and followed by air abrasion(blasting) with 50 microns aluminium oxide, reportedly will promote wetting by the liquid porcelain. 8. Improved wetting is then accompanied by an increase in adhesion through vanderwaals forces. www.indiandentalacademy.com
  87. 87. MECHANICAL RETENTION: • 1. The porcelain-bearing area of a metal casting contains many microscopic irregularities into which opaque porcelain may flow when fired. • 2. Air abrading the metal with aluminum oxide is believed to enhance mechanical retention further by eliminating surface irregularities ( stress concentrations) while increasing the overall surface area available for bonding. www.indiandentalacademy.com
  88. 88. 3. Despite it’s presence, mechanical retention’s contribution to bonding may be relatively limited. 4. Dental porcelain does not require a roughened area to bond to metal. In fact porcelain will fuse to a well polished surface, but some surface roughness is effective in increasing bonding forces. www.indiandentalacademy.com
  89. 89. COMPRESSION BONDING • Dental porcelain is strongest under compression and weakest under tension. • Hence , if the coefficient of thermal expansion of the metal substructure is greater than that of the porcelain placed over it, the porcelain should be placed under compression on cooling. • 1. When cooling a restoration with a fullporcelain veneer, the metal contracts faster than the porcelain but is resisted by the porcelain’s lower coefficient of thermal expansion. www.indiandentalacademy.com
  90. 90. • 2. This difference in contraction rates creates tensile forces on the metal and corresponding compressive forces on the porcelain. Without the wraparound effect created in a full porcelain restoration, there is less likelihood this compression bonding will develop fully. www.indiandentalacademy.com
  91. 91. THERMAL EXPANSION • Generally substances increase in the length and volume when they are heated. This phenomenon is called as thermal expansion. • The specific rate of change in length of a particular substance per unit change in temperature is called coefficient of linear expansion. • The rate of change in volume is called coefficient of cubical expansion. • These may generally be called coefficient of thermal expansion or simply thermal expansion. www.indiandentalacademy.com
  92. 92. RELATION BETWEEN METAL AND PORCELAIN • When porcelain is fused to metal, three possible relations can exist in thermal expansion: • 1. Thermal expansion (or contraction) is greater in porcelain than in metal. • 2. Thermal expansion (or contraction) is equal between metal and porcelain. • 3. Thermal expansion (or contraction) is greater in metal than in porcelain. www.indiandentalacademy.com
  93. 93. THERMAL EXPANSION IS GREATER IN PORCELAIN THAN IN METAL. • Greater thermal expansion in porcelain means that during the time after porcelain has lost thermoplastic fluidity in the course of cooling, but after melting of porcelain at high temperature, porcelain is apt to contract to be smaller and shorter than metal until it reaches room temperature. • Therefore, assuming that they are separated, there will be a difference in length between them. www.indiandentalacademy.com
  94. 94. • Hence porcelain becomes shorter after cooling although they had the same length before heating. • In the ceramo-metallic system, porcelain side is subjected to tensile stress while the metal side is subjected to compressive stress as they are fused together. As a result, the porcelain, which is very weak against tensile stress, will crack immediately. www.indiandentalacademy.com
  95. 95. THERMAL EXPANSION IS EQUAL BETWEEN METAL AND PORCELAIN • As metal and porcelain expand or contract at the same rate, there will be no difference in dimensions between them at all. • As a result, porcelain receives no stress from metal and thus cracking does not occur in the stable porcelain unless undue external force is applied. • It is very difficult, however, to obtain the identical curves for coefficient of thermal expansion between porcelain and metal, and under ordinary conditions there is a discrepancy to some extent. www.indiandentalacademy.com
  96. 96. THERMAL EXPANSION IS GREATER IN METAL THAN IN PORCELAIN. • In general, this thermal expansion relationship exists between metal and porcelain in the dental metal-ceramic system. • The objective of such a relationship is to obtain the most stable assembly after firing. • Fractures do not usually occur since porcelain has very high compression strength, although the porcelain side is subjected to compressive stress as the metal contracts more than porcelain during cooling to ambient temperature after firing. www.indiandentalacademy.com
  97. 97. • However, this does not mean that cracking will never occur. • If there is a significant difference in thermal expansion between metal and porcelain, a shearing force acts on their interface, and if stress is sufficiently great, cracking, or fracture may occur. www.indiandentalacademy.com
  98. 98. CHEMICAL BONDING • The single most significant mechanism of porcelain-metal attachment is a chemical bond between dental porcelain and the oxides on the surface of the metal substructure. • There are those who believe that two mechanisms might exist within the chemical (or molecular) bonding theory. • According to one hypothesis,the oxide layer is permanently bonded to the metal substructure on one side while the dental porcelain remains on the other. www.indiandentalacademy.com
  99. 99. • The oxide layer itself is sandwiched in between the metal substructure and the opaque porcelain. • This sandwich theory is undesirable in that a thick oxide layer might exist that would weaken the attachment of metal to porcelain. • The second, and more likely, theory suggests that the surface oxides dissolve, or are dissolved by the opaque porcelain layer. • The porcelain is then brought into atomic contact with the metal surface for enhanced wetting and direct chemical bonding so metal and porcelain share electrons. www.indiandentalacademy.com
  100. 100. • From a chemical standpoint, both covalent and ionic bonds are thought to form but only a monomolecular( single) layer of oxides is believed to be required for chemical bonding to occur. www.indiandentalacademy.com
  101. 101. PORCELAIN METAL BOND FAILURES • Metal ceramic alloys, whether noble or base metals, all oxidize differently because of variations in their composition. • If the oxidation process is not performed properly,the subsequent porcelain-metal bond may be weak. The consequences of bond failure,be the failure immediate or delayed,obviously costly. www.indiandentalacademy.com
  102. 102. PORCELAIN DELAMINATION • With base metal alloys, the separation of porcelain veneer from the metal sub structure can be more a loss of the attachment of the oxide layer that is either too thick or is poorly adherent to the metal sub structure. • The porcelain and oxide film retain their bond yet become detached or delaminated at the porcelain-metal junction. • Over oxidation is the particular problem with heavily oxidizing base metals www.indiandentalacademy.com
  103. 103. • In some instance bond failure may not be due to chemical bond failure.in contrarary,it may be due to too thick of the oxide layer or poor adherence of the oxide layer to the metal structure. • Excessive absorption of the oxides by porcelains can lower the coefficient of thermal expansion. www.indiandentalacademy.com
  104. 104. INCOMPITENT MATERIALS • Bond failure may occur due to physical incompatibility between porcelain and metal. • The difference in the coefficient of thermal expansion of porcelain and the metal may contribute to the failure of the bonding. www.indiandentalacademy.com
  105. 105. OVER OXIDATION/UNDER OXIDATION • The oxidation procedure varies for alloys of different compositions.so the process it self should not be taken for granted. • No one technique can be used for every type of metal ceramic alloy. • Careful processing followed by an assessment of post oxidation appearance of each casting will ensure that the procedure was accomplished correctly. www.indiandentalacademy.com
  106. 106. • Over oxidation or under oxidation should be reprocessed accordingly until uniform oxide of desired color and thickness recommended for the alloy involved. www.indiandentalacademy.com
  107. 107. CONTAMINATION • That that are demonstrated some form of contamination may not have to be remade. • Simple finishing, a substructure’s porcelain bearing area may be all that is necessary when surface de bonding becomes evident. www.indiandentalacademy.com
  108. 108. • • • • • • • • POCELAIN APPLICATION METHODS INSTRUMENTS AND EQIUPMENTS: Brushes Carving instruments Spatula Razor knifes Hemostat Condensation mallet or instrument. Glass or ceramic mixing slab www.indiandentalacademy.com
  109. 109. PORCELAIN FURNACE • • • • • Three types of the furnaces are available: Manual. Automatic. Programmable. There certain futures common to all types of the furnaces. • For example all low fusing porcelain are fired under vacuum rather than in atmospheric pressure.so, all furnaces are equipped so the firing chamber or muffle can be sealed and, with the aid of a pump,establish & maintain a vacuum during firing. www.indiandentalacademy.com
  110. 110. • In the event the vacuum does not reach an adequate level, or if the firing chamber does not properly seal, resulting in a loss of vacuum during the firing cycle, the quality of the fired porcelain will be compromised. • There will be significant loss of the translucency, And vitality in the fired porcelain. A porcelain furnace should have an adjustable rate of climb from the low entry temperature up to high firing temperature. www.indiandentalacademy.com
  111. 111. • Most furnaces can also be set to hold the work at a temperature for a a specified length of time as determined by case by case. • There two basic categories depending on the manner of entry into the muffle. • Form front to back • Front loading furnaces. • The front loading furnaces hotter near back of the muffle and cooler near door. • Those sub structures oxidized in the rear most portion of the muffle will have a significantly heavier oxide layer www.indiandentalacademy.com
  112. 112. • Furnaces in the second category have a vertical entry in to the muffle. With the vertical loading design,the muffle flat form with the restoration in the center is raised up to furnace muffle. • The vertical loading design reportedly provides a more uniform temperature distribution throughout the muffle and allows the work to be completely surrounded by the heating elements. www.indiandentalacademy.com
  113. 113. PORCELAIN CONDENSATION • Capillary action. • Vibration. • Spatulation. • Whipping. • Dry powder addition. www.indiandentalacademy.com
  114. 114. CAPILLARY ACTION • The technique of bottling a wet build up with absorbent paper uses surface tension to with draw liquid and packs the porcelains particle together. • Capillary action or surface tension alone does not remove all available liquid. • The cyclic action of vibration,or whipping followed by bottling is repeated until free liquid can no longer be forced to the surface of porcelain. • Usually delicate touch require to initiate this mechanism. www.indiandentalacademy.com
  115. 115. • An overly aggressive technique could dislodge the porcelain buildup form underlying metal sub structure. www.indiandentalacademy.com
  116. 116. VIBRATION • The easiest and simplest form of vibration created by passing serrated instrument over the neck of the hemostat. • If the restoration is left on the cast,the entire cast can be tapped or vibrated. • Whether the restoration is vibrated on hemostat or on cast the end result of vibration will be to force the excess water to the porcelain surface. • At this point, with the help of tissue paper the surface liquid is removed. www.indiandentalacademy.com
  117. 117. • There several devices to provide mechanical vibration such as, vibrating brushes, spatulas,and ultrasonic condensers. • Surface tension is the force that causes all liquids to contract to their smallest possible surface area. • This property accounts for the transformation of the water droplets in to the spherical mass. • In a wet bulk of porcelain, this force helps to pack the porcelain more tightly when vibrating & bottling. www.indiandentalacademy.com
  118. 118. SPATULATION • With this form of condensation,a spatula or porcelain carver is used to apply,rub the porcelain buildup to force the liquid to the surface. • This technique brings with it a greater likelihood of porcelain dislodgement, particularly if too much pressure is used especially with initial build up. www.indiandentalacademy.com
  119. 119. WHIPPING • This method actually be nothing more than variation of vibration technique. • As the porcelain built up, a no. 10 sable brush is rapidly moved over the porcelain surface with a whipping motion.the whipping action brings the liquid to the out side surface of the bottling. www.indiandentalacademy.com
  120. 120. DRY POWDWER ADDITION: • This method is less widely used. • This technique also referred as brush application method. • Dry porcelain powder sprayed over the wet porcelain surface. • This uses the existing liquid to moisten the powder addition. www.indiandentalacademy.com
  121. 121. POCELAIN APPLICATION METHODS. www.indiandentalacademy.com
  122. 122. OPAQUE PORCELIAN APPLICATION. www.indiandentalacademy.com
  123. 123. GLASS ROD TECHNIQUE • First, lightly wet the oxidized metal metal substructure to be veneered with distilled water and gently vibrate the casting for thorough wetting. www.indiandentalacademy.com
  124. 124. • Use point end of glass rod to apply the opaque porcelain.begin the opaquing most convex portion of the metal. www.indiandentalacademy.com
  125. 125. • Move the opaque towards the porcelain metal junction from one inter proximal area to to other & cover the incisal area. www.indiandentalacademy.com
  126. 126. • Lightly tap the hemostat with metal instrument to condense the opaque porcelain and excess opaquing liquid will raise to the surface. www.indiandentalacademy.com
  127. 127. • Place the edge of tissue,against the an edge of the moist opaque porcelain.hold the tissue in place until the liquid is absorbed and takes on a dull appearance. www.indiandentalacademy.com
  128. 128. • Blend the opaque at the porcelain metal junction to establish a gradual transition from opaque to external surface. www.indiandentalacademy.com
  129. 129. BRUSH TECHNIQUE • Opaque can also be applied with the brush.load the brush tip with opaque porcelain and carry it to the coping. www.indiandentalacademy.com
  130. 130. • Application of the opaque twice is also recommended.initially thin layer of the opaque and complete masking is followed. www.indiandentalacademy.com
  131. 131. DENTIN APPLICATION METHOD. www.indiandentalacademy.com
  132. 132. • Carefully return the cleaned,opaqued coping to the master cast.place folded tissue or bottling paper on the lingual side of the restoration. www.indiandentalacademy.com
  133. 133. • To minimize the potential for entrapping air in the porcelain, move the tip of the pointed brush through the mixed dentin porcelain.remove the brush with dentin porcelain captured on the brush tip. www.indiandentalacademy.com
  134. 134. • Apply the porcelain to the most convex area on the restoration. www.indiandentalacademy.com
  135. 135. • Gently push the porcelain to the intrproximal,incisal areas. www.indiandentalacademy.com
  136. 136. • Move the porcelain down to the incisal edge and lightly blot the build up to condense the porcelain on the substructure. www.indiandentalacademy.com
  137. 137. • To create the mesialfacial line angle,wipe the brush to dry it slightly and reduce the pointing then lightly move from the mesial gingival area to mesial-incisal area. www.indiandentalacademy.com
  138. 138. • Point the brush and add additional dentin porcelain to lingual aspect of the incisal edge.smooth and condense the incisal edge from the lingual and facial aspects. www.indiandentalacademy.com
  139. 139. www.indiandentalacademy.com
  140. 140. www.indiandentalacademy.com
  141. 141. • Use a razor knife to cut back the incisal edge from between 1.0to1.5mm www.indiandentalacademy.com
  142. 142. • Remove dentin porcelain at the mesial inter proximal line angle.extend the cut to the junction of the middle and gingival 1/3rd for younger patients. www.indiandentalacademy.com
  143. 143. • At the distal intrproximal line angle,make a cut form the incisal edge towards the gingival 1/3rd as far as required for the esthetics. www.indiandentalacademy.com
  144. 144. • Examine the restoration from an incisal view for symmetry and adequacy of the cut back. www.indiandentalacademy.com
  145. 145. ENAMEL APPLIACTION METHODS. www.indiandentalacademy.com
  146. 146. • With pointed brush,apply enamel porcelain to one corner of cutback. www.indiandentalacademy.com
  147. 147. • Add more enamel porcelain and move it across the facial surface in the incisal one third. www.indiandentalacademy.com
  148. 148. • Blend the enamel porcelain at the junction of middle and gingival 1/3rd &begin to establish the incisal edge & condense the porcelain by blotting periodically. www.indiandentalacademy.com
  149. 149. • Blend the enamel porcelain into gingival 1/3rd on the facial surface.Recreate the interproximal contours and line angles. www.indiandentalacademy.com
  150. 150. • Shape the mesialincisal corner as required for each case.examine the build up form incisal view&evaluate the overall shape . www.indiandentalacademy.com
  151. 151. ALTERNATIVE BUILD UP TECHNIQUE. www.indiandentalacademy.com
  152. 152. • Apply the opaque to mask the underlying metal. www.indiandentalacademy.com
  153. 153. • Complete & smooth the dentin buildup. www.indiandentalacademy.com
  154. 154. • Create three developmental lobes with the pointed brush. www.indiandentalacademy.com
  155. 155. • Invert the cast & place translucent porcelain in the two developmental groove.apply enamel porcelain to the inter proximal areas. www.indiandentalacademy.com
  156. 156. • Continue this process until the entire crown is built to full contour. www.indiandentalacademy.com
  157. 157. • Finally, use the whipping brush to gently smooth the entire porcelain build up. www.indiandentalacademy.com
  158. 158. • Once the porcelain has been fired,you should be able to observe demonstrable mamelons in the restoration. www.indiandentalacademy.com
  159. 159. PORCELAIN APLICATION FOR FIXED PARTIAL DENTURE. www.indiandentalacademy.com
  160. 160. • Apply and condense opaque porcelain.Cover any gray areas,and fire the prosthesis. www.indiandentalacademy.com
  161. 161. • Return the opaqued FPD to the master cast with a piece of tissue paper cut to cover the entire pontic area. www.indiandentalacademy.com
  162. 162. • Add a small portion of dentin porcelain to the under side of the pontic on the FPD frame work. www.indiandentalacademy.com
  163. 163. • Return the frame work to the master cast and gently rock it back and forth until it seats completely.Remove the frame work and inspect the tissue side of the pontic.this area should cover completely with porcelain and well condensed. www.indiandentalacademy.com
  164. 164. • Place the frame work back on the master cast and apply dentin porcelain or add and condense opacous dentin to the cervical areas of the three components. www.indiandentalacademy.com
  165. 165. • Complete the dentin build up. www.indiandentalacademy.com
  166. 166. • Create the developmental lobes.Use thin razor knife to cut through inter proximal areas and individualize the teeth. www.indiandentalacademy.com
  167. 167. • Add enamel veneering material. www.indiandentalacademy.com
  168. 168. • Condense the porcelain build up. www.indiandentalacademy.com
  169. 169. • Measure the mesialdistal width of each tooth with a Boley gauge.compare that measurement with porcelain build up. www.indiandentalacademy.com
  170. 170. • Use a knife or other instrument to make any necessary adjustments in the mesial-distal width. www.indiandentalacademy.com
  171. 171. • Facial view of the build up. www.indiandentalacademy.com
  172. 172. • Lingual view of the build up. www.indiandentalacademy.com
  173. 173. • Three unit FPD after firing. www.indiandentalacademy.com
  174. 174. FIRING PROCEDURES. • The large bulk of the build up will require more time to dry and pre heat than the opaque porcelain. • Put the restoration on saggar tray place it on the muffle stand of the furnace. • Properly matured porcelain have a slightly orange peel appearance when fired correctly. • Do not under fire the porcelain.porcelain that has not matured properly has no shine to the surface & internally has cloudy appearance. www.indiandentalacademy.com
  175. 175. • Restorations that are under fired porcelain often have to be stripped form metal and rebuilt. • Over fired porcelains appears to be glazed and the surface has little or none of the pebbly appearance. • The firing temperature is usually lowered 10 degrees with each correction firing, so that initial build up does not get affected. www.indiandentalacademy.com
  176. 176. Thank you www.indiandentalacademy.com Leader in continuing dental education www.indiandentalacademy.com

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