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SOLDERING


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DEFINITIONDEFINITION

Soldering involves joining twoSoldering involves joining twocomponents of metal with ancomponents of metal with an

intermediate metal whose meltingintermediate metal whose meltingtemperature is lower than the parenttemperature is lower than the parentmetal.metal.


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R EQUI R EMENTS OF AR EQUI R EMENTS OF A

SOLDER

SOLDER

F use safely below the sag or creepF use safely below the sag or creeptemperature of the parent alloy.temperature of the parent alloy.

Resist tarnish and corrosion.Resist tarnish and corrosion.Non pitting.Non pitting.F ree flowing.F ree flowing.Match the color of the parent metal.Match the color of the parent metal.


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C OMPOSITION OF SOLDE R SC OMPOSITION OF SOLDE R S

G oldG oldSilver Silver Copper Copper TinTin

ZincZincG old solders are designated byG old solders are designated byfineness.fineness.


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SOLDERING FLUXSOLDERING FLUX

F lux means flow.F lux means flow.Improve the flow of a metalImprove the flow of a metalChemicals that limit the flow of metalsChemicals that limit the flow of metalsare calledare called antifluxesantifluxes


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FUNCTIONS OF A FLUXFUNCTIONS OF A FLUX

P ROTECTORP ROTECTORIt covers the metal surface and preventsIt covers the metal surface and prevents

oxide formation.oxide formation.REDUCERREDUCER

It helps to reduce the oxides present on theIt helps to reduce the oxides present on themetal surface.metal surface.

SOLVENTSSOLVENTSIt dissolves any oxide presence and removesIt dissolves any oxide presence and removes

it.it.


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COMPOSITION OF A FLUXCOMPOSITION OF A FLUX

B orax glassB orax glassB oric acidB oric acidSilicaSilica


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ANTIFLUX ANTIFLUX

Used to control the flow of the metal.Used to control the flow of the metal.Most common antiMost common anti- -fluxes used isfluxes used isgraphite.graphite.B etter fluxes like Rouge in chloroformB etter fluxes like Rouge in chloroformcan be used.can be used.


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SOLDERINGSOLDERING

INVESTMENTINVESTMENT

This are silicaThis are silica bonded investmentsbonded investmentsthat fused quartz.that fused quartz.

F used quartz is used because it is theF used quartz is used because it is thelowest thermally expanding form of lowest thermally expanding form of silica.silica.


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SOLDERING FOR METALSOLDERING FOR METAL

CERAMIC RESTORATIONCERAMIC RESTORATION

It is usually done prior to ceramicIt is usually done prior to ceramicapplication hence it is also known asapplication hence it is also known as

pr e ce r amic solde r ing pr e ce r amic solde r ing ..P ost ceramic materials are alsoP ost ceramic materials are alsoavailable.available.


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P re ceramic soldering is done at aP re ceramic soldering is done at atemperature of 1075 to 1120 degreetemperature of 1075 to 1120 degree

celsius whereas post ceramiccelsius whereas post ceramicsoldering should be done at asoldering should be done at atemperature of 920 degree celsiustemperature of 920 degree celsius

because ceramic may begin to sag atbecause ceramic may begin to sag athigher temperatures.higher temperatures.


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P ost ceramic soldering should beP ost ceramic soldering should bedone after ceramic firing.done after ceramic firing.

Ceramic portions should be finishedCeramic portions should be finishedonly afetr soldering.only afetr soldering.


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ADVANTAGES OF PRE ADVANTAGES OF PRE

CERAMIC SOLDERINGCERAMIC SOLDERING

The metal framework can be solderedThe metal framework can be solderedand tried in prior to ceramic build up.and tried in prior to ceramic build up.

Minor casting errors can also beMinor casting errors can also bepatched up during ceramic build up.patched up during ceramic build up.


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DISADVANTAGES OF PREDISADVANTAGES OF PRE


Difficult to build ceramic onDifficult to build ceramic onalready soldered units.already soldered units.


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ADVANTAGES OF POST ADVANTAGES OF POST


P orcelain can be properly build upP orcelain can be properly build updue to better access.due to better access.


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DISADVANTAGES OF POSTDISADVANTAGES OF POST


The metal and porcelain may sag at highThe metal and porcelain may sag at highsoldering temperatures.soldering temperatures.

It is more technique sensitive.It is more technique sensitive.The solder should be reThe solder should be re- -glazed and reglazed and re- -fired.fired.


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OVEN SOLDERINGOVEN SOLDERING

P erformed under vacuum or air.P erformed under vacuum or air.

A piece of solder is placed in the A piece of solder is placed in the joint space and it is heated to a joint space and it is heated to astandard temperature in the furnace.standard temperature in the furnace.

Superior joint strength.Superior joint strength.


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DISADVANTAGESDISADVANTAGES

The parent metal will sag or meltThe parent metal will sag or melt

if heated for o long time.if heated for o long time.


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The solder should be melted using the soft The solder should be melted using the soft brush flame.brush flame.The flame should be constantly swipedThe flame should be constantly swipedover the solder for a period of 4over the solder for a period of 4 - -55minutes.minutes.

At no point of time the flame should be At no point of time the flame should beheld in a stationary position.held in a stationary position.


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INFRARED SOLDERINGINFRARED SOLDERING

Used for low fusing connectors.Used for low fusing connectors.

G ood accuracy.G ood accuracy.Similar strength as conventionalSimilar strength as conventionalsoldering.soldering.

P rotective eyewear is necessary.P rotective eyewear is necessary.


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LASER WELDINGLASER WELDING

Done to join Ti components of dentalDone to join Ti components of dentalcrowns, bridges and partial denture framecrowns, bridges and partial denture frame

works.works.P ulsed high power P ulsed high power N eodymium lase r sN eodymium lase r s areareused.used.

Low thermal influence preferred inLow thermal influence preferred indentistry.dentistry.Superior joint strength.Superior joint strength.


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SOLDERING TECHNIQUE

The design of the connector isdetermined while fabricating the waxpattern.

All the solder connectors requireabout 0.25mm parallel spacedbetween the parent components.The smaller units are insertedseparately in the mouth.


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A thick mix of quick setting plaster ismolded over the inserted units.

Once the plaster sets, it is removedalong with the inserted units.P laster index is inverted.

Components of the prosthesis will bevisible.


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A triangular piece of utility wax shouldbe placed to index restoration inorder to shape the soldering assembly.The units are invested and theinvestment is allowed to bench set.Invested wax is eliminated usingboiling water or chloroform.


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Area of the restoration surroundingthe joint should be coated with anti-flux.

After coating the flux and the anti-flux,the assembly is preheated in aburnout furnace.Connectors are soldered using atorch or a furnace.


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DISADVANTAGES

Not economical.


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METAL PREPARATIONMETAL PREPARATION

Any minor casting defects in the cutAny minor casting defects in the cutback area should be corrected.back area should be corrected.

Recovery includes sandRecovery includes sand- -blasting andblasting andultrasonic cleaning.ultrasonic cleaning.The gingival surface of the ponticThe gingival surface of the ponticshould be reduced.should be reduced.Gingival surface of the pontic shouldGingival surface of the pontic shouldalways be covered with porcelain.always be covered with porcelain.


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PORCELAIN APPLICATION After preparing the metal, an opaquelayer of porcelain should be appliedover the metal surface.G ingival surface of porcelain is coatedwith cervical porcelain.

Layer of cervical, body and incisalporcelains should be used to build upthe facial surface.


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P orcelain in the interdental area shouldbe sectioned to demarcate junction of the two units.

A separating liquid is applied over theedentulous ridge prior to building up the

gingival surface of the pontic.


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P ORCELAIN FIRING

Next the porcelain is fired as per themanufactures instruction.

After firing the core porcelain, glazeporcelain is added and fired as usual.


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ACRYLIC VENEERS

Similar to ceramic veneering exceptfor a few differences.

Major difference is that onlymechanical bonding exists betweenthe metal and resin.

Bond strength is considerably less.


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P ROCEDUREMechanical undercuts can be created bysprinkling plastic retentive pearls over thewax pattern before casting.The surface of the cast metal can beroughened using Al2O3 air abrasive unit.

A small quantity opaque resin is added

onto the metal surface.B

ody shade resinis added over the opaque resin andcontoured using a modelling instrument.


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The resin should be polymerisedunder pressure in a warm water bath.

Light cure resins are also available.Resin core should be carved toremove excess material. Space

should be provided to accommodateincisal shade resin.


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Finally incisal shade resin is addedand contoured.

After polymerization, the restoration isfinished and polished


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THANKING YOUTHANKING YOU

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