Casting alloys / dentistry website

DENTAL CASTINGDENTAL CASTING
ALLOYS.ALLOYS.
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com
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• CLASSIFICATION.CLASSIFICATION.
• DIFFERENT CONSTITUENTSDIFFERENT CONSTITUENTS
&THEIR ROLE&THEIR ROLE
• DIFFERENT ALLOY SYSTEMSDIFFERENT ALLOY SYSTEMS
THEIRTHEIR
ADVANTAGES &ADVANTAGES &www.indiandentalacademy.comwww.indiandentalacademy.com

•ALLOY:-ALLOY:- A MIXTURE OF TWO OR MOREA MIXTURE OF TWO OR MORE
METALS OR METALLOIDS THAT AREMETALS OR METALLOIDS THAT ARE
MUTUALLY SOLUBLE IN MOLTEN STATE.MUTUALLY SOLUBLE IN MOLTEN STATE.
•CASTING:-CASTING:- SOMETHNG THAT HAS BEENSOMETHNG THAT HAS BEEN
CAST IN A MOLD; AN OBJECT FORMED BYCAST IN A MOLD; AN OBJECT FORMED BY
THE SOLIDIFICATION OF A FLUID THAT HASTHE SOLIDIFICATION OF A FLUID THAT HAS
BEEN POURED OR INJECTED INTO MOLD.BEEN POURED OR INJECTED INTO MOLD.
• OROR
•THE ACT OF FORMING AN OBJECT IN ATHE ACT OF FORMING AN OBJECT IN A
MOLD.MOLD.

Requirements of the alloys:-Requirements of the alloys:-
1.A casting alloy must be able to produce1.A casting alloy must be able to produce
surface oxides for chemical bonding withsurface oxides for chemical bonding with
dental porcelain.dental porcelain.
2.A casting alloy should be formulated so its2.A casting alloy should be formulated so its
coefficient of thermal expansion is slightlycoefficient of thermal expansion is slightly
greater than that of the porcelain veneer togreater than that of the porcelain veneer to
maintain the metal porcelain attachment.maintain the metal porcelain attachment.

The alloy must have melting rangeThe alloy must have melting range
considerably higher than the fusing range ofconsiderably higher than the fusing range of
the dental porcelain fired on to it.the dental porcelain fired on to it.
The alloy must not under go distortion at theThe alloy must not under go distortion at the
the firing temperatures of the porcelain.the firing temperatures of the porcelain.
The first four requirements must be balancedThe first four requirements must be balanced
with technicians need for ease of handling.with technicians need for ease of handling.
A casting alloy should be biocompatible.A casting alloy should be biocompatible.

CLASSIFICATION OF THE DENTALCLASSIFICATION OF THE DENTAL
CASTING ALLOYSCASTING ALLOYS
THEY ARE CLASSIFIED BASED ON :-THEY ARE CLASSIFIED BASED ON :-
1.ALLOY CLASSIFICATION BASED ON1.ALLOY CLASSIFICATION BASED ON
FUNCTION.FUNCTION.
2.ALLOY CLASSIFICATION BASED ON COLOR2.ALLOY CLASSIFICATION BASED ON COLOR
&COMPOSITION.&COMPOSITION.
3.THE ADA CLASSIFICATION FOR CAST ALLOYS.3.THE ADA CLASSIFICATION FOR CAST ALLOYS.
4.AN ALTERNATIVE CLASSIFICATION SYSTEM4.AN ALTERNATIVE CLASSIFICATION SYSTEM
FOR METAL CERAMIC ALLOYS.FOR METAL CERAMIC ALLOYS.

CLASSIFICATION BASED ONCLASSIFICATION BASED ON
FUNCTIONFUNCTION
One of the oldest & simplest methods used toOne of the oldest & simplest methods used to
categorize casting alloys was devised by thecategorize casting alloys was devised by the
NATIONAL BUREAU OF STANDARDS INNATIONAL BUREAU OF STANDARDS IN
19321932..
The gold based crown & bridge metals of thatThe gold based crown & bridge metals of that
time were organized according to function intotime were organized according to function into
only four categories & describedonly four categories & described
type1,2,3,or4alloystype1,2,3,or4alloys
Alloys in each classification or type wereAlloys in each classification or type were
arranged based on their gold &platinum grouparranged based on their gold &platinum groupwww.indiandentalacademy.comwww.indiandentalacademy.com

• TYPE –1– SOFT.--- USED FOR THETYPE –1– SOFT.--- USED FOR THE
SMALL INLAYSSMALL INLAYS
•
• TYPE –2– MEDIUM.--- USED FORE THETYPE –2– MEDIUM.--- USED FORE THE
THREE QUTER CROWN,THIN BACKINGS.THREE QUTER CROWN,THIN BACKINGS.
• TYPE –3– HARD.--- USED FOR THE FULLTYPE –3– HARD.--- USED FOR THE FULL
CROWNS, ABUTMENTS & PONTICS.CROWNS, ABUTMENTS & PONTICS.
•
TYPE –4—EXTRA HARD---DENTURE BASETYPE –4—EXTRA HARD---DENTURE BASE
BARS,PARTIAL DENTURE FRAMEBARS,PARTIAL DENTURE FRAME
WORK, LONG SPAN FIXED PARTIALWORK, LONG SPAN FIXED PARTIAL

ALLOY CALSSIFICATION BASEDALLOY CALSSIFICATION BASED
ON COLOR &COMPOSITIONON COLOR &COMPOSITION
A second method of classification is toA second method of classification is to
describe alloys according to their color &describe alloys according to their color &
principal element.principal element.
1.YELLOW GOLDS:- yellow color,greater than1.YELLOW GOLDS:- yellow color,greater than
60% of the gold content.60% of the gold content.
2.WHITE GOLDS:-white color but more than2.WHITE GOLDS:-white color but more than
50%of the gold content.50%of the gold content.
3.LOW GOLDS:-usually yellow colored with3.LOW GOLDS:-usually yellow colored with
less than 60%of the gold.less than 60%of the gold.

HIGH PALLADIUM:-white colored ,withHIGH PALLADIUM:-white colored ,with
palladium the major component.also containspalladium the major component.also contains
small amount of gold &copper,cobalt.small amount of gold &copper,cobalt.
SILVER- PALLADIUM:-white coloredSILVER- PALLADIUM:-white colored
predominantly silver with substantial amountspredominantly silver with substantial amounts
of the palladium to provide nobility &to helpof the palladium to provide nobility &to help
control tarnish.control tarnish.
PALLADIUM- SILVER :-white colored withPALLADIUM- SILVER :-white colored with
palladium the major component ,pluspalladium the major component ,plus
substantial component of silver.substantial component of silver.www.indiandentalacademy.comwww.indiandentalacademy.com

ADA CLASSIFICATIONADA CLASSIFICATION
In 1984 ADA prepared a new classificationIn 1984 ADA prepared a new classification
for cast alloys.for cast alloys.
The system was devised for the identificationThe system was devised for the identification
in dental procedure codes,where the intrinsicin dental procedure codes,where the intrinsic
value of the metals in the castings providedvalue of the metals in the castings provided
to patient would influence the amount ofto patient would influence the amount of
reimbursement from insurance carriers.reimbursement from insurance carriers.
This system of the classification was notThis system of the classification was not
intended to indicate usage or performanceintended to indicate usage or performance
levels.levels.

• HIGH NOBLE:CONTAINS 40% GOLD,60%HIGH NOBLE:CONTAINS 40% GOLD,60%
OF THE NOBLE METALS.(Au-Ir-Os-Pt-Ru)OF THE NOBLE METALS.(Au-Ir-Os-Pt-Ru)
• NOBLE METAL:CONTAINS 25% OF THENOBLE METAL:CONTAINS 25% OF THE
NOBLE METAL ELEMENTS.NOBLE METAL ELEMENTS.
• PREDOMINANTLY BASEPREDOMINANTLY BASE
METAL:CONTAINS LESS THAN 25% OFMETAL:CONTAINS LESS THAN 25% OF
THE NOBLE METAL ELEMENTS.THE NOBLE METAL ELEMENTS.

AN ALTERNATIVEAN ALTERNATIVE
CLASSIFICATON SYSTEMCLASSIFICATON SYSTEM
With this method the alloys are classifiedWith this method the alloys are classified
based on composition & level of thebased on composition & level of the
constituent of the major content.constituent of the major content.
The alloys are first divided into two groups,The alloys are first divided into two groups,
1.Noble metal1.Noble metal
2.Non noble metals.2.Non noble metals.
Each system further divided into constituentEach system further divided into constituent
groups.groups.

• In 1984 ADA given classification of alloysIn 1984 ADA given classification of alloys
that are used for the metal ceramicthat are used for the metal ceramic
restorations.restorations.
• They are classified as,They are classified as,
• High noble.High noble.
• Noble.Noble.
• Predominantly base metal.Predominantly base metal.

HIGH NOBLE METALHIGH NOBLE METAL
ALLOYS.ALLOYS.

HIGH NOBLE ALLOYHIGH NOBLE ALLOY
SYSTEMS.SYSTEMS.
• Au-Pt-Pd.Au-Pt-Pd.
• Au-Pd-Ag.Au-Pd-Ag.
• Au-Pd.Au-Pd.

DIFFERENT ALLOYDIFFERENT ALLOY
SYSTEMS THEIRSYSTEMS THEIR
ADVANTAGESADVANTAGES
&DISADVANTAGES&DISADVANTAGES

Au-Pt-PdAu-Pt-Pd

COMPOSITION:-COMPOSITION:-
Gold:75%-88%Gold:75%-88%
Platinum:-8%Platinum:-8%
Palladium:-11%Palladium:-11%
Silver:-5%Silver:-5%
Trace elements of indium,iron,&tin areTrace elements of indium,iron,&tin are
used for the porcelain bonding.used for the porcelain bonding.

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.comwww.indiandentalacademy.com

•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.

Au-Pt-PdAu-Pt-Pd
• ADVANTAGESADVANTAGES
• EXCELLENTEXCELLENT
CASTABILITY&PORCCASTABILITY&PORC
ELAIN BONDINGELAIN BONDING
• EASY TO ADJUSTEASY TO ADJUST
&FINISH&FINISH
• TARNISH&CORROSITARNISH&CORROSI
ON RESISTANCEON RESISTANCE
• BIOCOMPATIBLEBIOCOMPATIBLE
• NOT TECHNIQUENOT TECHNIQUE
SENSITIVESENSITIVE
• DISADVANTAGESDISADVANTAGES
• Poor sagPoor sag
resistanceresistance
• Low hardnessLow hardness
• Low densityLow density
• High costHigh cost

•GOLD:-it provides the high levels of the tarnish
&corrosion.
•It increases melting range.
•It improves the wettability,burnishability
&increases the density.

Au-Pd-AgAu-Pd-Ag
Composition:-Composition:-
Gold:39%-53%Gold:39%-53%
Palladium:25%-35%Palladium:25%-35%
Silver:12%-22%Silver:12%-22%

• AdvantagesAdvantages
• Less expensiveLess expensive
• Improved rigidity&sagImproved rigidity&sag
• High nobility levelHigh nobility level
• DisadvantagesDisadvantages
• Silver content createsSilver content creates
potential for porcelainpotential for porcelain
discoloration.discoloration.
• High CTEHigh CTE
• Tarnish &corrosionTarnish &corrosion

GOLD-PALLADIUM ALLOY SYSTEMSGOLD-PALLADIUM ALLOY SYSTEMS
Gold:44%-55%Gold:44%-55%
Gallium:5%Gallium:5%
Indium & tin:8%-12%Indium & tin:8%-12%

• Excellent castabilityExcellent castability
• Good bond strengthGood bond strength
• Corrosion & tarnishCorrosion & tarnish
• Improved hardness &Improved hardness &
strengthstrength
• Low density.Low density.
• Not thermallyNot thermally
compatible withcompatible with
expansionexpansion
AdvantagesAdvantages

NOBLE ALLOY SYSTEMSNOBLE ALLOY SYSTEMS

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

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

• PALLADIUM:-- palladium is added toPALLADIUM:-- palladium is added to
increase the strength, hardness,increase the strength, hardness,
corrosion&tarnish resistance.corrosion&tarnish resistance.
• It elevates the alloy’s melting temperature.It elevates the alloy’s melting temperature.
• It improves the sag resistance.It improves the sag resistance.
• Palladium possess the a high affinity for thePalladium possess the a high affinity for the
hydrogen,oxygen& carbon.hydrogen,oxygen& carbon.
• It lowers the density of the gold basedIt lowers the density of the gold based
alloys.alloys.

• TIN:-TIN:-
• Tin is the hardening agent that acts as aTin is the hardening agent that acts as a
lower melting range of the of an alloy.lower melting range of the of an alloy.
• It also assists in oxide layer production forIt also assists in oxide layer production for
the porcelain bonding in gold based &the porcelain bonding in gold based &
palladium based alloys.palladium based alloys.
• Tin is the one of the key trace elements forTin is the one of the key trace elements for
the oxidation of the palladium silver alloys.the oxidation of the palladium silver alloys.

• Low cost & densityLow cost & density
• Good castability &Good castability &
porcelain bondingporcelain bonding
• Low hardnessLow hardness
• Excellent sag ,tarnishExcellent sag ,tarnish
& corrosion& corrosion
• Suitable for long spanSuitable for long span
fpd’sfpd’s
• DiscolorationDiscoloration
• Pd-Ag prone toPd-Ag prone to
absorb gasesabsorb gases
• High CTEHigh CTE
• May form internalMay form internal
oxides.oxides.
• Should not be cast inShould not be cast in
carbon cruciblecarbon crucible

PALLADIUM-COBALTPALLADIUM-COBALT
• composition:composition:
• palladium78%-88%.palladium78%-88%.
• cobalt 4%-10%cobalt 4%-10%
•
• trace elements oftrace elements of
gallium,indium are used.gallium,indium are used.

• Cobalt is used for alternative of the nickelCobalt is used for alternative of the nickel
based alloys, but the cobalt based alloysbased alloys, but the cobalt based alloys
are difficult to process.]are difficult to process.]
• Cobalt is added to in palladium alloys toCobalt is added to in palladium alloys to
increase the CTE,& acts as a strengthener.increase the CTE,& acts as a strengthener.

• Advantages.Advantages.
• Low costLow cost
• Good sag resistanceGood sag resistance
• GoodGood
castability,polishabiliycastability,polishabiliy
• Easier to solderEasier to solder
• Compatible with highCompatible with high
expansion porcelains.expansion porcelains.
• Produce aProduce a
thick,dark.oxide coloredthick,dark.oxide colored
layer may cause bluinglayer may cause bluing
of the porcelain.of the porcelain.
• More prone to gasMore prone to gas
absorption.absorption.

PALLADIUM-COPPERPALLADIUM-COPPER
• palladium 70-80%palladium 70-80%
• copper 9-15%copper 9-15%
• gold 1-2%gold 1-2%
• platinum 1-2%platinum 1-2%

• COPPER:-COPPER:-
• Copper serves as hardening agent.Copper serves as hardening agent.
• Lowers the melting range of alloy.Lowers the melting range of alloy.
• It helps to form an oxide layer for porcelainIt helps to form an oxide layer for porcelain
bonding.bonding.
• It lowers the density.It lowers the density.

• Advantages.Advantages.
• Good castability.Good castability.
• Low cost than gold.Low cost than gold.
• Good tarnish andGood tarnish and
corrosion resistant.corrosion resistant.
• Compatible withCompatible with
dental porcelains.dental porcelains.
• Produce dark,thick oxideProduce dark,thick oxide
layer.layer.
• May discolor someMay discolor some
porcelains.porcelains.
• Should not be cast in theShould not be cast in the
carbon crucibles.carbon crucibles.
• Absorbs gases.Absorbs gases.
• Suitable for the long spanSuitable for the long span
bridges.bridges.
• Difficult to polish.Difficult to polish.
• High hardnessHigh hardness

Pg-Ag-AuPg-Ag-Au
• composition:composition:
• palladium 75-86%palladium 75-86%
• silver 1-7%silver 1-7%
• gold less than 1%gold less than 1%
• Trace amounts of indium & gallium areTrace amounts of indium & gallium are
found.found.

• Improved sagImproved sag
resistance.resistance.
• Light colored oxideLight colored oxide
layer.layer.
• Relatively new alloyRelatively new alloy
group no data ongroup no data on
long termlong term
performances.performances.
• Prone to gaseousProne to gaseous
absorption.absorption.
• Should not be castShould not be cast
in carbon crucibles.in carbon crucibles.

• INDIUM:-INDIUM:-
• Lowers the melting range of the alloy.Lowers the melting range of the alloy.
• It improves the fluidity.It improves the fluidity.
• It has strengthening effect.It has strengthening effect.
• It is added to non gold based alloys to formIt is added to non gold based alloys to form
an oxide layer.an oxide layer.
• It enhances the tarnish & corrosiveIt enhances the tarnish & corrosive
resistance.resistance.

• GALLIUM:GALLIUM:
• It is added to the silver free porcelains toIt is added to the silver free porcelains to
compensate for the decreased CTEcompensate for the decreased CTE
created by silver removal.created by silver removal.

PREDOMINANTLY BASEPREDOMINANTLY BASE
METAL ALLOYSMETAL ALLOYS

• Ni-Cr-Mo-BeNi-Cr-Mo-Be
• Ni-Cr-MoNi-Cr-Mo
• Co-Cr-MoCo-Cr-Mo

NICKEL-CHROMIUM-MOLYBDENUM-NICKEL-CHROMIUM-MOLYBDENUM-
BERYLLIUM ALLOYSBERYLLIUM ALLOYS
COMPOSITION:COMPOSITION:
Nickel:62%-82%Nickel:62%-82%
Chromium:11-20%Chromium:11-20%
Beryllium:2%Beryllium:2%

•NICKEL:-it is base for the porcelain alloys.
•Its CTE similar to the gold
•It provides resistance to corrosion.
Lowers the melting temperature of the nickel
based alloys.
It improves the castability,improves polish ability.
Helps to control the oxide layer formation
BERYLLIUM:-

• Aluminum:-lowers the melting range of theAluminum:-lowers the melting range of the
nickel based alloys.nickel based alloys.
• It acts as a hardening agent.It acts as a hardening agent.
• It influences the oxide layer formation.It influences the oxide layer formation.
• With cobalt chromium alloys used for theWith cobalt chromium alloys used for the
metal ceramic restoration, aluminum is themetal ceramic restoration, aluminum is the
on of the element that is etched from theon of the element that is etched from the
alloy surface to create micro mechanicalalloy surface to create micro mechanical
retention for resin bonded retainers.retention for resin bonded retainers.

• IRON:-IRON:-
• Iron is added to some gold based porcelainIron is added to some gold based porcelain
for hardening & oxide production.for hardening & oxide production.
SILICON:-
•Silicon primarily as an oxide scavenger.
•It also act as a hardening agent.

• High resistanceHigh resistance
• It can produce thinIt can produce thin
castingscastings
• Poor thermal conductorPoor thermal conductor
• Can be etched.Can be etched.
• Cannot be used with NiCannot be used with Ni
sensitive patientssensitive patients
• Beryllium may be toxic toBeryllium may be toxic to
the technician & patientsthe technician & patients
• Bond failure may occurBond failure may occur
• High hardnessHigh hardness
• Difficult to solderDifficult to solder
• Difficult to cut throughDifficult to cut through
cemented castingscemented castings

NICKEL-CHROMIUM ALLOYSNICKEL-CHROMIUM ALLOYS
Nickel :62%-77%Nickel :62%-77%
Chromium :-11%-22%Chromium :-11%-22%

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

BORON:-
Boron is a de oxidizer.
It reduces the surface tension there by
increases the castability.
Reduce the ductility & increase the hardness.

• Do not containDo not contain
berylliumberyllium
• Low density meansLow density means
more castings permore castings per
ounce.ounce.
• Cannot be use withCannot be use with
nickel sensitivenickel sensitive
patientspatients
• Produce more oxidesProduce more oxides
than Ni-Cr-Be alloys.than Ni-Cr-Be alloys.
• May not cast as wellMay not cast as well
as Ni-Cr-Be alloysas Ni-Cr-Be alloys

COBALT – CHROMIUM ALLOYSCOBALT – CHROMIUM ALLOYS
Cobalt:53%-68%Cobalt:53%-68%
Chromium:25%-34%Chromium:25%-34%
Trace elements of molybdenumTrace elements of molybdenum
ruthenium are added.ruthenium are added.

CHROMIUM:-CHROMIUM:-
• Chromium is a solid solution hardening agentChromium is a solid solution hardening agent
that contributes to corrosion resistance.that contributes to corrosion resistance.
• COBALT:-used as alternative to the nickelCOBALT:-used as alternative to the nickel
based alloys.based alloys.
• Cobalt included in the high palladium alloysCobalt included in the high palladium alloys
to increase the CTE.to increase the CTE.
• It also acts a strengthener.It also acts a strengthener.

• Molybdenum improves corrosionMolybdenum improves corrosion
resistance,influences the oxide layer,helpfulresistance,influences the oxide layer,helpful
in adjusting CTE in nickel based alloys.in adjusting CTE in nickel based alloys.

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

• ADVANTAGESADVANTAGES
• DO NOT CONTAINDO NOT CONTAIN
NICKELNICKEL
• DO NOT CONTAINDO NOT CONTAIN
BERYLLIUMBERYLLIUM
• POOR THERMALPOOR THERMAL
CONDUCTORSCONDUCTORS
• LOW DENSITYLOW DENSITY
• LOW COSTLOW COST
• DISADVANTAGESDISADVANTAGES
• MORE DIFFICULT TOMORE DIFFICULT TO
PROCESS THAN NIPROCESS THAN NI
BASE ALLOYSBASE ALLOYS
• HIGH HARDNESSHIGH HARDNESS
• OXIDE MORE THANOXIDE MORE THAN
BOTH NI BASEDBOTH NI BASED
ALLOYSALLOYS
• NO INFORMATIONNO INFORMATION
ON LONG TERMON LONG TERM
CLINICAL STUDIES.CLINICAL STUDIES.

SOLDERING.SOLDERING.

• SOLDERING:-A group of process that joinSOLDERING:-A group of process that join
metal by heating them to a suitablemetal by heating them to a suitable
temperature below the solidus of thetemperature below the solidus of the
substrate metals & applying a filler metalsubstrate metals & applying a filler metal
having liquidus not exceeding 450 degreehaving liquidus not exceeding 450 degree
centigrade that melts and flows by capillarycentigrade that melts and flows by capillary
attraction between the parts with outattraction between the parts with out
appreciably affecting the dimension of joinedappreciably affecting the dimension of joined
structure.structure.
• In dentistry,many metals are joined byIn dentistry,many metals are joined by
brazing,although,the term soldering is used.brazing,although,the term soldering is used.www.indiandentalacademy.comwww.indiandentalacademy.com

• BRAZING:The process of joining metalsBRAZING:The process of joining metals
above 450 degree centigrade.above 450 degree centigrade.
• WELDING:-The joining of two or more metalWELDING:-The joining of two or more metal
pieces by applying heat, pressure,or bothpieces by applying heat, pressure,or both
with or without filler material, to producewith or without filler material, to produce
localized union across the interface throughlocalized union across the interface through
fusion or diffusion.fusion or diffusion.
• SOLDERING FLUX: A material used toSOLDERING FLUX: A material used to
prevent the formation of,or to dissolve &prevent the formation of,or to dissolve &
facilitate removal of,oxides & otherfacilitate removal of,oxides & other
undesirable substances that may reduce theundesirable substances that may reduce thewww.indiandentalacademy.comwww.indiandentalacademy.com

SOLDERING OF FIXEDSOLDERING OF FIXED
PARTIAL DENTURES.PARTIAL DENTURES.

PHYSICAL REQUIREMENTS OFPHYSICAL REQUIREMENTS OF
SOLDER MATERIALSSOLDER MATERIALS
• Resistance to tarnish & corrosion.Resistance to tarnish & corrosion.
• Fusion temperature 90-180 degreeFusion temperature 90-180 degree
Fahrenheit below the parts to be joined.Fahrenheit below the parts to be joined.
• Free flowing when melted.Free flowing when melted.
• Resistance to pitting.Resistance to pitting.
• At least as strong as the parts to be joined.At least as strong as the parts to be joined.
• Color compatible with the parts to be joined.Color compatible with the parts to be joined.

SOLDERING FLUXESSOLDERING FLUXES
• Flux is Latin word means flow.Dental do notFlux is Latin word means flow.Dental do not
flow or wet the metallic surfaces that have anflow or wet the metallic surfaces that have an
oxide layer.The flux aid in the removal of theoxide layer.The flux aid in the removal of the
oxide layer so as to increase the flow of theoxide layer so as to increase the flow of the
molten solder.molten solder.
• In addition the flux also dissolves theIn addition the flux also dissolves the
impurities,prevents the oxidation of theimpurities,prevents the oxidation of the
metals.metals.
• Fluxes used commonly are:Fluxes used commonly are:
• Borax glass– 55%.Borax glass– 55%.
• Boric acid --35%Boric acid --35%
• Silica-- 10%.Silica-- 10%.www.indiandentalacademy.comwww.indiandentalacademy.com

• ANTI FLUXANTI FLUX
• Anti flux is a material that is used to confineAnti flux is a material that is used to confine
the flow of the molten solder over the metalsthe flow of the molten solder over the metals
being joined.being joined.
• The commonly used anti fluxes are pencilThe commonly used anti fluxes are pencil
markings, graphite lines, iron rouge.markings, graphite lines, iron rouge.

Fundamental considerationsFundamental considerations
• Position accurately the uncontaminated partsPosition accurately the uncontaminated parts
to be joined.to be joined.
• Determine the solder gaps and configuration.Determine the solder gaps and configuration.
• Place the flux and solder within the jointPlace the flux and solder within the joint
space.space.
• Heat the parent metal and solder until theHeat the parent metal and solder until the
solder flows, filling the joint space.solder flows, filling the joint space.
• Remove the heat as soon as possible.Remove the heat as soon as possible.
• Inspect the connection and correct fInspect the connection and correct f
necessary.necessary.
• Gap to be maintained is 0.3mm.Gap to be maintained is 0.3mm.www.indiandentalacademy.comwww.indiandentalacademy.com

• ARMAMENTAIRUMARMAMENTAIRUM
• Plaster bowl & spatulaPlaster bowl & spatula
• Impression plaster.Impression plaster.
• Bite registration paste.Bite registration paste.
• Index tray or tongue blade.Index tray or tongue blade.
• Petrolatum.Petrolatum.
• Laboratory knife with no.25 blade.Laboratory knife with no.25 blade.
• PKT waxing instrument no 1& 2.PKT waxing instrument no 1& 2.
• Straight hand piece.Straight hand piece.
• Soldering investment.Soldering investment.
• Vibrator.Vibrator.

• Fisher burner &Fisher burner &
matches.matches.
• Tripod screen.Tripod screen.
• SolderSolder
• Blow pipe.Blow pipe.
• Tooth brush.Tooth brush.

• Remove the provisional restoration from theRemove the provisional restoration from the
patient’s mouth make certain that there arepatient’s mouth make certain that there are
no temporary cement left on the toothno temporary cement left on the tooth
preparation.preparation.
• Try in the single retainer first and thenTry in the single retainer first and then
retainer pontic combination, verify theretainer pontic combination, verify the
marginal fitmarginal fit
• Adjust the occlusion, do not polish theAdjust the occlusion, do not polish the
casting at this stage.because polishing rougecasting at this stage.because polishing rouge
is iron-di- oxide, a specific anti flux for

• Mix a small amount ofMix a small amount of
fast settingfast setting
impression plaster &impression plaster &
place it on plasticplace it on plastic
index tray orindex tray or
thoroughly wet tonguethoroughly wet tongue
depressor.depressor.

1.1. Place the tray inPlace the tray in
the mouth overthe mouth over
thethe
castings.oncecastings.once
the plaster set,the plaster set,
remove theremove the
template andtemplate and
check for thecheck for the
accuracyaccuracy

• Trim the excessTrim the excess
plaster so that afterplaster so that after
seating the template,seating the template,
it is possible to coverit is possible to cover
their margins withtheir margins with
solderingsoldering
investment.lute theinvestment.lute the
castings with thecastings with the
sticky wax.sticky wax.

• A strip of boxing waxA strip of boxing wax
2.5mm thick wide2.5mm thick wide
wrapped around thewrapped around the
index.index.

• Mix the solderingMix the soldering
investment accordinginvestment according
to the manufacturerto the manufacturer
instructions.completelinstructions.completel
y fill the interior of they fill the interior of the
retainer castings.retainer castings.
Care to avoid buryingCare to avoid burying
the prosthesis in thethe prosthesis in the
investment.investment.

• Remove the plasterRemove the plaster
template & trim thetemplate & trim the
investment so, thatinvestment so, that
soldering modelsoldering model
allows the readyallows the ready
access of heat to theaccess of heat to the
joint area.joint area.

• Heat the solderingHeat the soldering
model sufficiently tomodel sufficiently to
vaporize waxvaporize wax
remaining in the joint.remaining in the joint.

• While the joint is stillWhile the joint is still
warm coat the solderwarm coat the solder
with flux and placewith flux and place
the solder in thethe solder in the
place.place.

• Reheat the soldering model until the solderReheat the soldering model until the solder
flows.flows.
• Remove the flame, apply bluish flame inRemove the flame, apply bluish flame in
circular manner around the solder model.circular manner around the solder model.
• As the solder is about to flow; it slumps andAs the solder is about to flow; it slumps and
loses rectangular definition.loses rectangular definition.
• Use only reducing portions of the flame,Use only reducing portions of the flame,
characterized by shiny areas on the metalcharacterized by shiny areas on the metal
directly under the flame.directly under the flame.
• Allow the prosthesis for the bench cool toAllow the prosthesis for the bench cool to
heat treat the metals properly.heat treat the metals properly.
• Try the assembled prosthesis in the mouthTry the assembled prosthesis in the mouth
after finishing & polishing.after finishing & polishing.www.indiandentalacademy.comwww.indiandentalacademy.com

POST VENERINGPOST VENERING
SOLDERINGSOLDERING

• Try in the units in the mouth & makeTry in the units in the mouth & make
necessary adjustments.necessary adjustments.
• Remove the FPD from the mouth,cut theRemove the FPD from the mouth,cut the
joint using disk.joint using disk.
• A soldering index is made with the quickA soldering index is made with the quick
setting plaster.setting plaster.

• Making the plasterMaking the plaster
index.index.

• Cyanoacrylate liquidCyanoacrylate liquid
resin is squeezedresin is squeezed
onto the joint space.onto the joint space.

• To preventTo prevent
investment forminvestment form
contaminating thecontaminating the
ceramic place 1.0mmceramic place 1.0mm
thick ivory wax overthick ivory wax over
gingival one half togingival one half to
2/32/3rdrd
of the facialof the facial
surfaces of thesurfaces of the
retainer and pontic.retainer and pontic.

• Mix a small amount ofMix a small amount of
the solderingthe soldering
investment andinvestment and
carefully vibrate intocarefully vibrate into
the crowns.the crowns.

• Soldering investmentSoldering investment
is placed over the flatis placed over the flat
surface.surface.

• Put the FPD into thePut the FPD into the
investment.investment.

• Investment is pushedInvestment is pushed
over the lingualover the lingual
surfaces of the FPDsurfaces of the FPD

• The investment isThe investment is
trimmed leavingtrimmed leaving
3.0mm around the3.0mm around the
castings. The entirecastings. The entire
block is beveled.block is beveled.

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

• The wax layerThe wax layer
separates theseparates the
investment andinvestment and
porcelain.porcelain.

• After the waxAfter the wax
removal, a spaceremoval, a space
between porcelainbetween porcelain
and investmentand investment
protects the porcelain.protects the porcelain.

MECHANISM OFMECHANISM OF
PORCELAIN –METALPORCELAIN –METAL
ATTACHMENTATTACHMENT
• Four theoriesFour theories have been proposedhave been proposed
to explain the processes that lead toto explain the processes that lead to
porcelain-to-metal bonding:porcelain-to-metal bonding:
• 1. Van der waals forces.1. Van der waals forces.
• 2. Mechanical retention.2. Mechanical retention.
• 3. Compression bonding.3. Compression bonding.
• 4. Direct chemical bonding.4. Direct chemical bonding.

VAN DER WAALS FORCES.VAN DER WAALS FORCES.
1. The attraction between charged atoms that1. The attraction between charged atoms that
are in intimate contact yet do not actuallyare in intimate contact yet do not actually
exchange electrons is derived from van derexchange electrons is derived from van der
waals forces.waals forces.
2. These secondary forces are generated more2. These secondary forces are generated more
by a physical attraction between chargedby a physical attraction between charged
particles than by an actual sharing or exchangeparticles than by an actual sharing or exchange
of electrons in primary(chemical) bonding.of electrons in primary(chemical) bonding.
3. Van der waals forces are generally weak,3. Van der waals forces are generally weak,
because nearly all the positive and negativebecause nearly all the positive and negative
charges present in these atoms are satisfied incharges present in these atoms are satisfied in
a single molecule.a single molecule.

4. It is also believed that bonding entails4. It is also believed that bonding entails
some measure of true adhesion based onsome measure of true adhesion based on
the extent to which the metal substructurethe extent to which the metal substructure
is wetted by the softened dental porcelain.is wetted by the softened dental porcelain.
5. The better the wetting of the metal5. The better the wetting of the metal
surface, greater the vanderwaal’s forces.surface, greater the vanderwaal’s forces.
6. Furthermore, porcelain’s adhesion to6. Furthermore, porcelain’s adhesion to
metal can be diminished or enhanced bymetal can be diminished or enhanced by
alterations in the surfacealterations in the surface
characters(texture) of the porcelain-characters(texture) of the porcelain-
bearing surface on the substructure.bearing surface on the substructure.

7. A rough, contaminated metal surface7. A rough, contaminated metal surface
will inhibit wetting and reduce thewill inhibit wetting and reduce the
vanderwaals bond strength. On the othervanderwaals bond strength. On the other
hand, a slightly textured surface, createdhand, a slightly textured surface, created
by finishing with uncontaminatedby finishing with uncontaminated
aluminum oxide abrasives and followedaluminum oxide abrasives and followed
by air abrasion(blasting) with 50 micronsby air abrasion(blasting) with 50 microns
aluminium oxide, reportedly will promotealuminium oxide, reportedly will promote
wetting by the liquid porcelain.wetting by the liquid porcelain.
8. Improved wetting is then accompanied8. Improved wetting is then accompanied
by an increase in adhesion throughby an increase in adhesion through
vanderwaals forces.vanderwaals forces.

MECHANICAL RETENTION:MECHANICAL RETENTION:
• 1. The porcelain-bearing area of a metal1. The porcelain-bearing area of a metal
casting contains many microscopiccasting contains many microscopic
irregularities into which opaque porcelainirregularities into which opaque porcelain
may flow when fired.may flow when fired.
• 2. Air abrading the metal with aluminum2. Air abrading the metal with aluminum
oxide is believed to enhance mechanicaloxide is believed to enhance mechanical
retention further by eliminating surfaceretention further by eliminating surface
irregularities ( stress concentrations) whileirregularities ( stress concentrations) while
increasing the overall surface areaincreasing the overall surface area
available for bonding.available for bonding.

3. Despite it’s presence, mechanical3. Despite it’s presence, mechanical
retention’s contribution to bonding mayretention’s contribution to bonding may
be relatively limited.be relatively limited.
4. Dental porcelain does not require a4. Dental porcelain does not require a
roughened area to bond to metal. In factroughened area to bond to metal. In fact
porcelain will fuse to a well polishedporcelain will fuse to a well polished
surface, but some surface roughness issurface, but some surface roughness is
effective in increasing bonding forces.effective in increasing bonding forces.

COMPRESSION BONDINGCOMPRESSION BONDING
• Dental porcelain is strongest underDental porcelain is strongest under
compression and weakest under tension.compression and weakest under tension.
• Hence , if the coefficient of thermalHence , if the coefficient of thermal
expansion of the metal substructure isexpansion of the metal substructure is
greater than that of the porcelain placedgreater than that of the porcelain placed
over it, the porcelain should be placedover it, the porcelain should be placed
under compression on cooling.under compression on cooling.
• 1. When cooling a restoration with a1. When cooling a restoration with a
full-porcelain veneer, the metal contractsfull-porcelain veneer, the metal contracts
faster than the porcelain but is resistedfaster than the porcelain but is resisted
by the porcelain’s lower coefficient ofby the porcelain’s lower coefficient of
thermal expansion.thermal expansion.

• 2. This difference in contraction rates2. This difference in contraction rates
creates tensile forces on the metal andcreates tensile forces on the metal and
corresponding compressive forces on thecorresponding compressive forces on the
porcelain. Without the wraparound effectporcelain. Without the wraparound effect
created in a full porcelain restoration,created in a full porcelain restoration,
there is less likelihood this compressionthere is less likelihood this compression
bonding will develop fully.bonding will develop fully.

THERMAL EXPANSIONTHERMAL EXPANSION
• Generally substances increase in theGenerally substances increase in the
length and volume when they are heated.length and volume when they are heated.
This phenomenon is called as thermalThis phenomenon is called as thermal
expansion.expansion.
• The specific rate of change in length of aThe specific rate of change in length of a
particular substance per unit change inparticular substance per unit change in
temperature is called coefficient of lineartemperature is called coefficient of linear
expansion.expansion.
• The rate of change in volume is calledThe rate of change in volume is called
coefficient of cubical expansion.coefficient of cubical expansion.
• These may generally be called coefficientThese may generally be called coefficient
of thermal expansion or simply thermalof thermal expansion or simply thermal
expansion.expansion.www.indiandentalacademy.comwww.indiandentalacademy.com

RELATION BETWEEN METALRELATION BETWEEN METAL
AND PORCELAINAND PORCELAIN
• When porcelain is fused to metal, threeWhen porcelain is fused to metal, three
possible relations can exist in thermalpossible relations can exist in thermal
expansion:expansion:
• 1. Thermal expansion (or contraction)1. Thermal expansion (or contraction)
is greater in porcelain than in metal.is greater in porcelain than in metal.
is equal between metal and porcelain.is equal between metal and porcelain.
is greater in metal than in porcelain.is greater in metal than in porcelain.

THERMAL EXPANSION ISTHERMAL EXPANSION IS
GREATERGREATER ININ PORCELAIN THANPORCELAIN THAN
IN METAL.IN METAL.
• Greater thermal expansion in porcelainGreater thermal expansion in porcelain
means that during the time after porcelainmeans that during the time after porcelain
has lost thermoplastic fluidity in thehas lost thermoplastic fluidity in the
course of cooling, but after melting ofcourse of cooling, but after melting of
porcelain at high temperature, porcelain isporcelain at high temperature, porcelain is
apt to contract to be smaller and shorterapt to contract to be smaller and shorter
than metal until it reaches roomthan metal until it reaches room
temperature.temperature.
• Therefore, assuming that they areTherefore, assuming that they are
separated, there will be a difference inseparated, there will be a difference in
length between them.length between them.www.indiandentalacademy.comwww.indiandentalacademy.com

• Hence porcelain becomes shorter afterHence porcelain becomes shorter after
cooling although they had the samecooling although they had the same
length before heating.length before heating.
• In the ceramo-metallic system, porcelainIn the ceramo-metallic system, porcelain
side is subjected to tensile stress whileside is subjected to tensile stress while
the metal side is subjected tothe metal side is subjected to
compressive stress as they are fusedcompressive stress as they are fused
together. As a result, the porcelain, whichtogether. As a result, the porcelain, which
is very weak against tensile stress, willis very weak against tensile stress, will
crack immediately.crack immediately.

THERMAL EXPANSION IS EQUALTHERMAL EXPANSION IS EQUAL
BETWEEN METAL ANDBETWEEN METAL AND
PORCELAINPORCELAIN
• As metal and porcelain expand orAs metal and porcelain expand or
contract at the same rate, there will be nocontract at the same rate, there will be no
difference in dimensions between them atdifference in dimensions between them at
all.all.
• As a result, porcelain receives no stressAs a result, porcelain receives no stress
from metal and thus cracking does notfrom metal and thus cracking does not
occur in the stable porcelain unless undueoccur in the stable porcelain unless undue
external force is applied.external force is applied.
• It is very difficult, however, to obtain theIt is very difficult, however, to obtain the
identical curves for coefficient of thermalidentical curves for coefficient of thermal
expansion between porcelain and metal,expansion between porcelain and metal,
and under ordinary conditions there is aand under ordinary conditions there is awww.indiandentalacademy.comwww.indiandentalacademy.com

THERMAL EXPANSION ISTHERMAL EXPANSION IS
GREATER IN METAL THAN INGREATER IN METAL THAN IN
PORCELAIN.PORCELAIN.
• In general, this thermal expansionIn general, this thermal expansion
relationship exists between metal andrelationship exists between metal and
porcelain in the dental metal-ceramicporcelain in the dental metal-ceramic
system.system.
• The objective of such a relationship is toThe objective of such a relationship is to
obtain the most stable assembly afterobtain the most stable assembly after
firing.firing.
• Fractures do not usually occur sinceFractures do not usually occur since
porcelain has very high compressionporcelain has very high compression
strength, although the porcelain side isstrength, although the porcelain side is
subjected to compressive stress as thesubjected to compressive stress as the
metal contracts more than porcelainmetal contracts more than porcelain

• However, this does not mean thatHowever, this does not mean that
cracking will never occur.cracking will never occur.
• If there is a significant difference inIf there is a significant difference in
thermal expansion between metal andthermal expansion between metal and
porcelain, a shearing force acts on theirporcelain, a shearing force acts on their
interface, and if stress is sufficiently great,interface, and if stress is sufficiently great,
cracking, or fracture may occur.cracking, or fracture may occur.

CHEMICAL BONDINGCHEMICAL BONDING
• The single most significant mechanism ofThe single most significant mechanism of
porcelain-metal attachment is a chemicalporcelain-metal attachment is a chemical
bond between dental porcelain and thebond between dental porcelain and the
oxides on the surface of the metaloxides on the surface of the metal
substructure.substructure.
• There are those who believe that twoThere are those who believe that two
mechanisms might exist within themechanisms might exist within the
chemical (or molecular) bonding theory.chemical (or molecular) bonding theory.
• According to one hypothesis,the oxideAccording to one hypothesis,the oxide
layer is permanently bonded to the metallayer is permanently bonded to the metal
substructure on one side while the dentalsubstructure on one side while the dental
porcelain remains on the other.porcelain remains on the other.www.indiandentalacademy.comwww.indiandentalacademy.com

• The oxide layer itself is sandwiched inThe oxide layer itself is sandwiched in
between the metal substructure and thebetween the metal substructure and the
opaque porcelain.opaque porcelain.
• This sandwich theory is undesirable inThis sandwich theory is undesirable in
that a thick oxide layer might exist thatthat a thick oxide layer might exist that
would weaken the attachment of metal towould weaken the attachment of metal to
porcelain.porcelain.
• The second, and more likely, theoryThe second, and more likely, theory
suggests that the surface oxidessuggests that the surface oxides
dissolve, or are dissolved by the opaquedissolve, or are dissolved by the opaque
porcelain layer.porcelain layer.
• The porcelain is then brought into atomicThe porcelain is then brought into atomic
contact with the metal surface forcontact with the metal surface for
enhanced wetting and direct chemicalenhanced wetting and direct chemical
bonding so metal and porcelain sharewww.indiandentalacademy.comwww.indiandentalacademy.com

• From a chemical standpoint, bothFrom a chemical standpoint, both
covalent and ionic bonds are thought tocovalent and ionic bonds are thought to
form but only a monomolecular( single)form but only a monomolecular( single)
layer of oxides is believed to belayer of oxides is believed to be
required for chemical bonding to occur.required for chemical bonding to occur.

PORCELAIN METAL BONDPORCELAIN METAL BOND
FAILURESFAILURES
• Metal ceramic alloys, whether noble or baseMetal ceramic alloys, whether noble or base
metals, all oxidize differently because ofmetals, all oxidize differently because of
variations in their composition.variations in their composition.
• If the oxidation process is not performedIf the oxidation process is not performed
properly,the subsequent porcelain-metalproperly,the subsequent porcelain-metal
bond may be weak. The consequences ofbond may be weak. The consequences of
bond failure,be the failure immediate orbond failure,be the failure immediate or
delayed,obviously costly.delayed,obviously costly.

PORCELAIN DELAMINATIONPORCELAIN DELAMINATION
• With base metal alloys, the separation ofWith base metal alloys, the separation of
porcelain veneer from the metal subporcelain veneer from the metal sub
structure can be more a loss of thestructure can be more a loss of the
attachment of the oxide layer that is eitherattachment of the oxide layer that is either
too thick or is poorly adherent to the metaltoo thick or is poorly adherent to the metal
sub structure.sub structure.
• The porcelain and oxide film retain theirThe porcelain and oxide film retain their
bond yet become detached or delaminatedbond yet become detached or delaminated
at the porcelain-metal junction.at the porcelain-metal junction.
• Over oxidation is the particular problem withOver oxidation is the particular problem with
heavily oxidizing base metalsheavily oxidizing base metals

• In some instance bond failure may not beIn some instance bond failure may not be
due to chemical bond failure.in contrarary,itdue to chemical bond failure.in contrarary,it
may be due to too thick of the oxide layer ormay be due to too thick of the oxide layer or
poor adherence of the oxide layer to thepoor adherence of the oxide layer to the
metal structure.metal structure.
• Excessive absorption of the oxides byExcessive absorption of the oxides by
porcelains can lower the coefficient ofporcelains can lower the coefficient of
thermal expansion.thermal expansion.

INCOMPITENT MATERIALSINCOMPITENT MATERIALS
• Bond failure may occur due to physicalBond failure may occur due to physical
incompatibility between porcelain and metal.incompatibility between porcelain and metal.
• The difference in the coefficient of thermalThe difference in the coefficient of thermal
expansion of porcelain and the metal mayexpansion of porcelain and the metal may
contribute to the failure of the bonding.contribute to the failure of the bonding.

OVER OXIDATION/UNDEROVER OXIDATION/UNDER
OXIDATIONOXIDATION
• The oxidation procedure varies for alloys ofThe oxidation procedure varies for alloys of
different compositions.so the process it selfdifferent compositions.so the process it self
should not be taken for granted.should not be taken for granted.
• No one technique can be used for everyNo one technique can be used for every
type of metal ceramic alloy.type of metal ceramic alloy.
• Careful processing followed by anCareful processing followed by an
assessment of post oxidation appearance ofassessment of post oxidation appearance of
each casting will ensure that the procedureeach casting will ensure that the procedure
was accomplished correctly.was accomplished correctly.

• Over oxidation or under oxidation should beOver oxidation or under oxidation should be
reprocessed accordingly until uniform oxidereprocessed accordingly until uniform oxide
of desired color and thickness recommendedof desired color and thickness recommended
for the alloy involved.for the alloy involved.

CONTAMINATIONCONTAMINATION
• That that are demonstrated some form ofThat that are demonstrated some form of
contamination may not have to be remade.contamination may not have to be remade.
• Simple finishing, a substructure’s porcelainSimple finishing, a substructure’s porcelain
bearing area may be all that is necessarybearing area may be all that is necessary
when surface de bonding becomeswhen surface de bonding becomes
evident.evident.

POCELAIN APPLICATIONPOCELAIN APPLICATION
METHODSMETHODS
• INSTRUMENTS AND EQIUPMENTS:INSTRUMENTS AND EQIUPMENTS:
• BrushesBrushes
• Carving instrumentsCarving instruments
• SpatulaSpatula
• Razor knifesRazor knifes
• HemostatHemostat
• Condensation mallet or instrument.Condensation mallet or instrument.
• Glass or ceramic mixing slabGlass or ceramic mixing slab

PORCELAIN FURNACEPORCELAIN FURNACE
• Three types of the furnaces are available:Three types of the furnaces are available:
• Manual.Manual.
• Automatic.Automatic.
• Programmable.Programmable.
• There certain futures common to all types of theThere certain futures common to all types of the
furnaces.furnaces.
• For example all low fusing porcelain are fired underFor example all low fusing porcelain are fired under
vacuum rather than in atmospheric pressure.so, allvacuum rather than in atmospheric pressure.so, all
furnaces are equipped so the firing chamber orfurnaces are equipped so the firing chamber or
muffle can be sealed and, with the aid of amuffle can be sealed and, with the aid of a
pump,establish & maintain a vacuum during firing.pump,establish & maintain a vacuum during firing.

• In the event the vacuum does not reach anIn the event the vacuum does not reach an
adequate level, or if the firing chamber doesadequate level, or if the firing chamber does
not properly seal, resulting in a loss ofnot properly seal, resulting in a loss of
vacuum during the firing cycle, the quality ofvacuum during the firing cycle, the quality of
the fired porcelain will be compromised.the fired porcelain will be compromised.
• There will be significant loss of theThere will be significant loss of the
translucency,translucency,
And vitality in the fired porcelain.And vitality in the fired porcelain.
A porcelain furnace should have an adjustableA porcelain furnace should have an adjustable
rate of climb from the low entry temperaturerate of climb from the low entry temperature
up to high firing temperature.up to high firing temperature.

• Most furnaces can also be set to hold the work at aMost furnaces can also be set to hold the work at a
temperature for a a specified length of time astemperature for a a specified length of time as
determined by case by case.determined by case by case.
• There two basic categories depending on theThere two basic categories depending on the
manner of entry into the muffle.manner of entry into the muffle.
• Form front to backForm front to back
• Front loading furnaces.Front loading furnaces.
• The front loading furnaces hotter near back of theThe front loading furnaces hotter near back of the
muffle and cooler near door.muffle and cooler near door.
• Those sub structures oxidized in the rear mostThose sub structures oxidized in the rear most
portion of the muffle will have a significantly heavierportion of the muffle will have a significantly heavier
oxide layeroxide layer

• Furnaces in the second category have aFurnaces in the second category have a
vertical entry in to the muffle. With thevertical entry in to the muffle. With the
vertical loading design,the muffle flat formvertical loading design,the muffle flat form
with the restoration in the center is raised upwith the restoration in the center is raised up
to furnace muffle.to furnace muffle.
• The vertical loading design reportedlyThe vertical loading design reportedly
provides a more uniform temperatureprovides a more uniform temperature
distribution throughout the muffle and allowsdistribution throughout the muffle and allows
the work to be completely surrounded by thethe work to be completely surrounded by the
heating elements.heating elements.

PORCELAIN CONDENSATIONPORCELAIN CONDENSATION
• Capillary action.Capillary action.
• Vibration.Vibration.
• Spatulation.Spatulation.
• Whipping.Whipping.
• Dry powder addition.Dry powder addition.www.indiandentalacademy.comwww.indiandentalacademy.com

CAPILLARY ACTIONCAPILLARY ACTION
• The technique of bottling a wet build up withThe technique of bottling a wet build up with
absorbent paper uses surface tension to withabsorbent paper uses surface tension to with
draw liquid and packs the porcelains particledraw liquid and packs the porcelains particle
together.together.
• Capillary action or surface tension aloneCapillary action or surface tension alone
does not remove all available liquid.does not remove all available liquid.
• The cyclic action of vibration,or whippingThe cyclic action of vibration,or whipping
followed by bottling is repeated until freefollowed by bottling is repeated until free
liquid can no longer be forced to the surfaceliquid can no longer be forced to the surface
of porcelain.of porcelain.
• Usually delicate touch require to initiate thisUsually delicate touch require to initiate this
mechanism.mechanism. www.indiandentalacademy.comwww.indiandentalacademy.com

• An overly aggressive technique couldAn overly aggressive technique could
dislodge the porcelain buildup formdislodge the porcelain buildup form
underlying metal sub structure.underlying metal sub structure.

VIBRATIONVIBRATION
• The easiest and simplest form of vibrationThe easiest and simplest form of vibration
created by passing serrated instrument overcreated by passing serrated instrument over
the neck of the hemostat.the neck of the hemostat.
• If the restoration is left on the cast,the entireIf the restoration is left on the cast,the entire
cast can be tapped or vibrated.cast can be tapped or vibrated.
• Whether the restoration is vibrated onWhether the restoration is vibrated on
hemostat or on cast the end result ofhemostat or on cast the end result of
vibration will be to force the excess water tovibration will be to force the excess water to
the porcelain surface.the porcelain surface.
• At this point, with the help of tissue paperAt this point, with the help of tissue paper
the surface liquid is removed.the surface liquid is removed.www.indiandentalacademy.comwww.indiandentalacademy.com

• There several devices to provideThere several devices to provide
mechanical vibration such as, vibratingmechanical vibration such as, vibrating
brushes, spatulas,and ultrasonicbrushes, spatulas,and ultrasonic
condensers.condensers.
• Surface tension is the force that causes allSurface tension is the force that causes all
liquids to contract to their smallest possibleliquids to contract to their smallest possible
surface area.surface area.
• This property accounts for theThis property accounts for the
transformation of the water droplets in to thetransformation of the water droplets in to the
spherical mass.spherical mass.
• In a wet bulk of porcelain, this force helps toIn a wet bulk of porcelain, this force helps to
pack the porcelain more tightly whenpack the porcelain more tightly when

SPATULATIONSPATULATION
• With this form of condensation,a spatula orWith this form of condensation,a spatula or
porcelain carver is used to apply,rub theporcelain carver is used to apply,rub the
porcelain buildup to force the liquid to theporcelain buildup to force the liquid to the
surface.surface.
• This technique brings with it a greaterThis technique brings with it a greater
likelihood of porcelain dislodgement,likelihood of porcelain dislodgement,
particularly if too much pressure is usedparticularly if too much pressure is used
especially with initial build up.especially with initial build up.

WHIPPINGWHIPPING
• This method actually be nothing more thanThis method actually be nothing more than
variation of vibration technique.variation of vibration technique.
• As the porcelain built up, a no. 10 sableAs the porcelain built up, a no. 10 sable
brush is rapidly moved over the porcelainbrush is rapidly moved over the porcelain
surface with a whipping motion.the whippingsurface with a whipping motion.the whipping
action brings the liquid to the out sideaction brings the liquid to the out side
surface of the bottling.surface of the bottling.

DRY POWDWER ADDITIONDRY POWDWER ADDITION::
• This method is less widely used.This method is less widely used.
• This technique also referred as brushThis technique also referred as brush
application method.application method.
• Dry porcelain powder sprayed over the wetDry porcelain powder sprayed over the wet
porcelain surface.porcelain surface.
• This uses the existing liquid to moisten theThis uses the existing liquid to moisten the
powder addition.powder addition.

POCELAIN APPLICATIONPOCELAIN APPLICATION
METHODS.METHODS.

OPAQUE PORCELIANOPAQUE PORCELIAN
APPLICATION.APPLICATION.

GLASS ROD TECHNIQUEGLASS ROD TECHNIQUE
• First, lightly wet theFirst, lightly wet the
oxidized metal metaloxidized metal metal
substructure to be veneered with distilledsubstructure to be veneered with distilled
water and gently vibrate the casting forwater and gently vibrate the casting for
thorough wetting.thorough wetting.

• Use point end ofUse point end of
glass rod to apply theglass rod to apply the
opaqueopaque
porcelain.begin theporcelain.begin the
opaquing mostopaquing most
convex portion of theconvex portion of the
metal.metal.

• Move the opaqueMove the opaque
towards the porcelaintowards the porcelain
metal junction frommetal junction from
one inter proximalone inter proximal
area to to other &area to to other &
cover the incisal area.cover the incisal area.

• Lightly tap theLightly tap the
hemostat with metalhemostat with metal
instrument toinstrument to
condense the opaquecondense the opaque
porcelain and excessporcelain and excess
opaquing liquid willopaquing liquid will
raise to the surface.raise to the surface.

• Place the edge ofPlace the edge of
tissue,against the antissue,against the an
edge of the moistedge of the moist
opaque porcelain.holdopaque porcelain.hold
the tissue in placethe tissue in place
until the liquid isuntil the liquid is
absorbed and takesabsorbed and takes
on a dull appearance.on a dull appearance.

• Blend the opaque atBlend the opaque at
the porcelain metalthe porcelain metal
junction to establish ajunction to establish a
gradual transitiongradual transition
from opaque tofrom opaque to
external surface.external surface.

BRUSH TECHNIQUEBRUSH TECHNIQUE
• Opaque can also beOpaque can also be
applied with theapplied with the
brush.load the brushbrush.load the brush
tip with opaquetip with opaque
porcelain and carry itporcelain and carry it
to the coping.to the coping.

• Application of theApplication of the
opaque twice is alsoopaque twice is also
recommended.initiallyrecommended.initially
thin layer of thethin layer of the
opaque and completeopaque and complete
masking is followed.masking is followed.

DENTIN APPLICATIONDENTIN APPLICATION
METHOD.METHOD.

• Carefully return theCarefully return the
cleaned,opaquedcleaned,opaqued
coping to the mastercoping to the master
cast.place foldedcast.place folded
tissue or bottlingtissue or bottling
paper on the lingualpaper on the lingual
side of theside of the
restoration.restoration.

• To minimize theTo minimize the
potential for entrappingpotential for entrapping
air in the porcelain,air in the porcelain,
move the tip of themove the tip of the
pointed brush throughpointed brush through
the mixed dentinthe mixed dentin
porcelain.remove theporcelain.remove the
brush with dentinbrush with dentin
porcelain captured onporcelain captured on
the brush tip.the brush tip.

• Apply the porcelain toApply the porcelain to
the most convex areathe most convex area
on the restoration.on the restoration.

• Gently push theGently push the
porcelain to theporcelain to the
intrproximal,incisalintrproximal,incisal
areas.areas.

• Move the porcelainMove the porcelain
down to the incisaldown to the incisal
edge and lightly blotedge and lightly blot
the build up tothe build up to
condense thecondense the
porcelain on theporcelain on the
substructure.substructure.

• To create the mesial-To create the mesial-
facial line angle,wipefacial line angle,wipe
the brush to dry itthe brush to dry it
slightly and reduceslightly and reduce
the pointing thenthe pointing then
lightly move from thelightly move from the
mesial gingival areamesial gingival area
to mesial-incisal area.to mesial-incisal area.

• Point the brush andPoint the brush and
add additional dentinadd additional dentin
porcelain to lingualporcelain to lingual
aspect of the incisalaspect of the incisal
edge.smooth andedge.smooth and
condense the incisalcondense the incisal
edge from the lingualedge from the lingual
and facial aspects.and facial aspects.

• Use a razor knife toUse a razor knife to
cut back the incisalcut back the incisal
edge from betweenedge from between
1.0to1.5mm1.0to1.5mm

• Remove dentinRemove dentin
porcelain at theporcelain at the
mesial inter proximalmesial inter proximal
line angle.extend theline angle.extend the
cut to the junction ofcut to the junction of
the middle andthe middle and
gingival 1/3gingival 1/3rdrd
forfor
younger patients.younger patients.

• At the distalAt the distal
intrproximal lineintrproximal line
angle,make a cutangle,make a cut
form the incisal edgeform the incisal edge
towards the gingivaltowards the gingival
1/31/3rdrd
as far as requiredas far as required
for the esthetics.for the esthetics.

• Examine theExamine the
restoration from anrestoration from an
incisal view forincisal view for
symmetry andsymmetry and
adequacy of the cutadequacy of the cut
back.back.

ENAMEL APPLIACTIONENAMEL APPLIACTION
METHODS.METHODS.

• With pointedWith pointed
brush,apply enamelbrush,apply enamel
porcelain to oneporcelain to one
corner of cutback.corner of cutback.

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

• Blend the enamelBlend the enamel
porcelain at theporcelain at the
junction of middle andjunction of middle and
gingival 1/3gingival 1/3rdrd
&begin&begin
to establish the incisalto establish the incisal
edge & condense theedge & condense the
porcelain by blottingporcelain by blotting
periodically.periodically.

• Blend the enamelBlend the enamel
porcelain into gingivalporcelain into gingival
1/31/3rdrd
on the facialon the facial
surface.Recreate thesurface.Recreate the
interproximal contoursinterproximal contours
and line angles.and line angles.

• Shape the mesial-Shape the mesial-
incisal corner asincisal corner as
required for eachrequired for each
case.examine thecase.examine the
build up form incisalbuild up form incisal
view&evaluate theview&evaluate the
overall shape .overall shape .

ALTERNATIVE BUILD UPALTERNATIVE BUILD UP
TECHNIQUE.TECHNIQUE.

• Apply the opaque toApply the opaque to
mask the underlyingmask the underlying
metal.metal.

• Complete & smoothComplete & smooth
the dentin buildup.the dentin buildup.

• Create threeCreate three
developmental lobesdevelopmental lobes
with the pointedwith the pointed
brush.brush.

• Invert the cast &Invert the cast &
place translucentplace translucent
porcelain in the twoporcelain in the two
developmentaldevelopmental
groove.apply enamelgroove.apply enamel
porcelain to the interporcelain to the inter
proximal areas.proximal areas.

• Continue this processContinue this process
until the entire crownuntil the entire crown
is built to full contour.is built to full contour.

• Finally, use theFinally, use the
whipping brush towhipping brush to
gently smooth thegently smooth the
entire porcelain buildentire porcelain build
up.up.

• Once the porcelainOnce the porcelain
has been fired,youhas been fired,you
should be able toshould be able to
observeobserve
demonstrabledemonstrable
mamelons in themamelons in the
restoration.restoration.

PORCELAIN APLICATIONPORCELAIN APLICATION
FORFOR
FIXED PARTIAL DENTURE.FIXED PARTIAL DENTURE.

• Apply and condenseApply and condense
opaqueopaque
porcelain.Cover anyporcelain.Cover any
gray areas,and firegray areas,and fire
the prosthesis.the prosthesis.

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

• Add a small portion ofAdd a small portion of
dentin porcelain to thedentin porcelain to the
under side of theunder side of the
pontic on the FPDpontic on the FPD
frame work.frame work.

• Return the frame workReturn the frame work
to the master cast andto the master cast and
gently rock it back andgently rock it back and
forth until it seatsforth until it seats
completely.Remove thecompletely.Remove the
frame work and inspectframe work and inspect
the tissue side of thethe tissue side of the
pontic.this area shouldpontic.this area should
cover completely withcover completely with
porcelain and wellporcelain and well
condensed.condensed.

• Place the frame workPlace the frame work
back on the masterback on the master
cast and apply dentincast and apply dentin
porcelain or add andporcelain or add and
condense opacouscondense opacous
dentin to the cervicaldentin to the cervical
areas of the threeareas of the three
components.components.

• Complete the dentinComplete the dentin
build up.build up.

• Create theCreate the
developmentaldevelopmental
lobes.Use thin razorlobes.Use thin razor
knife to cut throughknife to cut through
inter proximal areasinter proximal areas
and individualize theand individualize the
teeth.teeth.

• Add enamelAdd enamel
veneering material.veneering material.

• Condense theCondense the
porcelain build up.porcelain build up.

• Measure the mesial-Measure the mesial-
distal width of eachdistal width of each
tooth with atooth with a BBoleyoley
gauge.compare thatgauge.compare that
measurement withmeasurement with
porcelain build up.porcelain build up.

• Use a knife or otherUse a knife or other
instrument to makeinstrument to make
any necessaryany necessary
adjustments in theadjustments in the
mesial-distal width.mesial-distal width.

• Facial view of theFacial view of the
build up.build up.

• Lingual view of theLingual view of the
build up.build up.

• Three unit FPD afterThree unit FPD after
firing.firing.

FIRING PROCEDURES.FIRING PROCEDURES.
• The large bulk of the build up will requireThe large bulk of the build up will require
more time to dry and pre heat than themore time to dry and pre heat than the
opaque porcelain.opaque porcelain.
• Put the restoration on saggar tray place it onPut the restoration on saggar tray place it on
the muffle stand of the furnace.the muffle stand of the furnace.
• Properly matured porcelain have a slightlyProperly matured porcelain have a slightly
orange peel appearance when firedorange peel appearance when fired
correctly.correctly.
• Do not under fire the porcelain.porcelain thatDo not under fire the porcelain.porcelain that
has not matured properly has no shine tohas not matured properly has no shine to
the surface & internally has cloudythe surface & internally has cloudywww.indiandentalacademy.comwww.indiandentalacademy.com

• Restorations that are under fired porcelainRestorations that are under fired porcelain
often have to be stripped form metal andoften have to be stripped form metal and
rebuilt.rebuilt.
• Over fired porcelains appears to be glazedOver fired porcelains appears to be glazed
and the surface has little or none of theand the surface has little or none of the
pebbly appearance.pebbly appearance.
• The firing temperature is usually lowered 10The firing temperature is usually lowered 10
degrees with each correction firing, so thatdegrees with each correction firing, so that
initial build up does not get affected.initial build up does not get affected.

Thank you
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