Connectors in fpd/ continued dental education

INDIAN DENTAL ACADEMY
Leader in continuing dental education
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•Introduction
•Definition
•Design and requirements of connectors
•Types and choice selection
•Indications of each connector
•Advantages and disadvantages of each type
•Material science
a. Soldering
b. Soldering flux and antiflux
c. Soldering investment
d Heat source
CONTENTSCONTENTS

Selection of techniquesSelection of techniques
a) Pre-ceramic solderinga) Pre-ceramic soldering
b) Post -ceramic solderingb) Post -ceramic soldering
c) Oven solderingc) Oven soldering
d) Torch solderingd) Torch soldering
ProcedureProcedure
a) Occlusal soldering index (plaster ora) Occlusal soldering index (plaster or Znoe)Znoe)
d) Auto-polymerizing indexd) Auto-polymerizing index
c) Wax removal and preheatingc) Wax removal and preheating
d) Torch soldering (Low heat) and high heatd) Torch soldering (Low heat) and high heat
e) Oven soldering or furme solderinge) Oven soldering or furme soldering
f) Infra red solderingf) Infra red soldering
-- ReferencesReferences
-- ConclusionConclusion

INTRODUCTIONINTRODUCTION
""CConnectors", the term itself indicates connector oronnectors", the term itself indicates connector or
something that connects one thing to the other. Forsomething that connects one thing to the other. For
two thing to be joined together, there should be atwo thing to be joined together, there should be a
medium for it. In other words, something that willmedium for it. In other words, something that will
connects them together to make them look as one.connects them together to make them look as one.
This is true in every walk of life and also true inThis is true in every walk of life and also true in
case of fixed partial denture. If the components of acase of fixed partial denture. If the components of a
fixed partial denture is made individually they mustfixed partial denture is made individually they must
be joined and this can be accomplished by thebe joined and this can be accomplished by the
connectors.connectors.

DEFINITIONDEFINITION
The connector is that part of a fixed partial denture or splintThe connector is that part of a fixed partial denture or splint
that joins the individual components (retainers or pontics) together.that joins the individual components (retainers or pontics) together.
(Rosensteil)(Rosensteil)
ACCORDING TO GPT-7:
In fixed prosthodontics,the portion of a fixed partial denture
That unites the retainer and pontic.
ACCORDING TO SHEILENBERG:
That part of fixed partial denture which connects pontic and
Retainer and can be rigid or non-rigid.

DESIGN REQUIREMENTSDESIGN REQUIREMENTS

DESIGN REQUIREMENTSDESIGN REQUIREMENTS
 Wide to prevent distortion or fracture in function, but not excessivelyWide to prevent distortion or fracture in function, but not excessively
large to interfere with effective plaque control and in metal ceramic alarge to interfere with effective plaque control and in metal ceramic a
large connector may also display metal.large connector may also display metal.
 Connectors made with an elliptical cross section will be strongest ifConnectors made with an elliptical cross section will be strongest if
their major axis is parallel to the applied force, but due to the existingtheir major axis is parallel to the applied force, but due to the existing
anatomy, this is not possible.anatomy, this is not possible.
 For ease of plaque control, the connectors should occupy theFor ease of plaque control, the connectors should occupy the
normal anatomic interproximal area. But to improve esthetics andnormal anatomic interproximal area. But to improve esthetics and
also without much effect on plaque control, anterior connectors arealso without much effect on plaque control, anterior connectors are
placed towards lingual.placed towards lingual.

REQUIREMENTS OF CONNECTORSREQUIREMENTS OF CONNECTORS ::
A connector should be sufficiently strong toA connector should be sufficiently strong to
resist all the forces of mastication andresist all the forces of mastication and
there should be no likelihood of it wearingthere should be no likelihood of it wearing
and fracturing during a life time.and fracturing during a life time.
They should be placed as lingually andThey should be placed as lingually and
incisally as possible for self cleansing.incisally as possible for self cleansing.
Depth of connector should always beDepth of connector should always be
sufficient to provide adequate strength.sufficient to provide adequate strength.

• It should occupy a gap width ofIt should occupy a gap width of
about 0.25mm.about 0.25mm.
• The tooth must be prepared so asThe tooth must be prepared so as
to preserve the interproximalto preserve the interproximal
embrasure and occupy the normalembrasure and occupy the normal
anatomic interproximal areas.anatomic interproximal areas.
• The connectors should be large toThe connectors should be large to
withstand distortion.withstand distortion.

Types :Types :
A)A) Rigid connectorsRigid connectors
-cast-cast
oror
-soldered-soldered
B) Non-rigid connectorsB) Non-rigid connectors
 Tenon- mortiseTenon- mortise
 Loop connectorsLoop connectors
 Split ponticSplit pontic
 Cross pin and wing connectorsCross pin and wing connectors
 Dove – tailDove – tail

.. A)A) Rigid connectorsRigid connectors
1) They are used to unite retainers and pontics in a fixed - fixed partial1) They are used to unite retainers and pontics in a fixed - fixed partial
denture.denture.
2) These connectors are used when the entire load on the pontic is to be2) These connectors are used when the entire load on the pontic is to be
transfered directly to the abutments.transfered directly to the abutments.
INDICATIONS:
CONTRA INDICATIONS:
1) In cases where existing diastema is to be maintained.
2) In case of tilted abutments.
3) In abutments with differing long axis.
4) In long span bridges.

ADVANTAGES:
1) Easy to fabricate.
2) Less armamentarium required.
3) Can easily be fabricated by laboratory people.
4) Less time consuming.
RIGID CONNECTORS CAN BE EITHER CAST AS A
SINGLE UNIT OR JOINED BY SOLDERING.
SOLDERING CAN BE PERFORMED EITHER BEFORE
CERAMIC APPLICATION (PRE-CERAMIC) OR AFTER
CERAMIC APPLICATION(POST CERAMIC).

A rigid connection can be made by casting as part of a multiunit waxA rigid connection can be made by casting as part of a multiunit wax
pattern or by soldering.pattern or by soldering.
The design of rigid connector is incorporated into the wax pattern.The design of rigid connector is incorporated into the wax pattern.
connectors that are to be soldered are sectioned in the wax patternconnectors that are to be soldered are sectioned in the wax pattern
with a ribbon saw so that when the components are cast they can bewith a ribbon saw so that when the components are cast they can be
joined on a flat, parallel and at a controlled distance of 0.13mm.joined on a flat, parallel and at a controlled distance of 0.13mm.
DESIGN INCORPORATION IN RIGID CONNECTORS:

NON-RIGID CONNECTORSNON-RIGID CONNECTORS ::

There are several situations in which the use ofThere are several situations in which the use of
non-rigid connectors is indicated, either to -non-rigid connectors is indicated, either to -
Relieve stress orRelieve stress or
To accommodate malaligned fixed partialTo accommodate malaligned fixed partial
denture abutments.denture abutments.
Among those used are :Among those used are :
Dove tail connectors (key andDove tail connectors (key and
ways) or (tenon – Mortise)ways) or (tenon – Mortise)
Loop connectorsLoop connectors
Split ponticSplit pontic
Cross pin and wing connectors.Cross pin and wing connectors.
Indications for non rigid connectors

1) This technique is best suited for releiving stress at midspan on long1) This technique is best suited for releiving stress at midspan on long
pontics.Consists of a mortise (female) prepared within the contour ofpontics.Consists of a mortise (female) prepared within the contour of
the retainer and a tenon (male) attached to the pontic.the retainer and a tenon (male) attached to the pontic.
2 )In periodontically weakened abutments.2 )In periodontically weakened abutments.
3) In cases of long fixed partial dentures.3) In cases of long fixed partial dentures.
4) In cases of heavy occlusal forces.4) In cases of heavy occlusal forces.
DOVE TAILDOVE TAIL
INDICATIONS:

ADVANTAGES:
1)Releive stress on abutments.
2)Acts as a splint of periodontically weakened teeth.
3)Allows for easy repair. In case of fracture, not the whole assembly
has to be repaired only the defective segment has to be removed
and repaired.
CONTRAINDICATIONS:
1)Cannot be used in short abutments.
2)Medically compromised patients.
3)Patients not willing for extensive tooth preprations.
DISADVANTAGES:
1)Time consuming.
2)Cost factor.
3)Require extensive tooth prepration.

Pattern fabrication for Tenon-mortise connector:Pattern fabrication for Tenon-mortise connector:
 The wax pattern for the retainer on the pier abutment isThe wax pattern for the retainer on the pier abutment is
fabricated on the working cast.fabricated on the working cast.
 When a plastic pattern is used for the key and key way, aWhen a plastic pattern is used for the key and key way, a
deep box form is carved into the distal surface of the waxdeep box form is carved into the distal surface of the wax
pattern to create space for the placement of plastic key waypattern to create space for the placement of plastic key way
pattern.pattern.
 It must be parallel the path of withdrawal of the otherIt must be parallel the path of withdrawal of the other
retainer, which is achieved by a dental surveyor.retainer, which is achieved by a dental surveyor.
 Place the working cast, with the wax pattern seated on thePlace the working cast, with the wax pattern seated on the
table of a surveyor. Assemble the key and key way portiontable of a surveyor. Assemble the key and key way portion
of the connector, and lock the mandrel that extends fromof the connector, and lock the mandrel that extends from
the top of the key portion of the pattern into the verticalthe top of the key portion of the pattern into the vertical
spindle of the surveying instrument.spindle of the surveying instrument.
 Manipulate the surveyor table until the mandrel andManipulate the surveyor table until the mandrel and
attachments are parallel with the path of insertion of theattachments are parallel with the path of insertion of the
distal preparation.distal preparation.

- Then lower the plastic pattern to the middle retainer wax- Then lower the plastic pattern to the middle retainer wax
pattern and lute it in place with sticky wax.pattern and lute it in place with sticky wax.
- Remove the key portion and complete the middle retainer- Remove the key portion and complete the middle retainer
wax pattern by blending the distal surface with the key way.wax pattern by blending the distal surface with the key way.
- The pattern is then invested, burned out and cast. After the- The pattern is then invested, burned out and cast. After the
casting has been cleaned and air abraded, carefully cut off anycasting has been cleaned and air abraded, carefully cut off any
part of the key way portion of the attachment that protrudespart of the key way portion of the attachment that protrudes
above the occlusal surface.above the occlusal surface.
- Place the casting on the working cast, and place the- Place the casting on the working cast, and place the
prefabricated plastic pattern for the key into the key way, at thisprefabricated plastic pattern for the key into the key way, at this
point the pontic wax pattern is attached to the plastic key.point the pontic wax pattern is attached to the plastic key.
- The pontic pattern is completed, removed from the working- The pontic pattern is completed, removed from the working
cast, invested, burned out and cast. After the casting iscast, invested, burned out and cast. After the casting is
recovered from the investment, the mandrel and any excess onrecovered from the investment, the mandrel and any excess on
the top portion of the key are carefully reduced. So the key andthe top portion of the key are carefully reduced. So the key and
key way are flush.key way are flush.

LOOP CONNECTORSLOOP CONNECTORS ::
 Used when an existing diastema is to beUsed when an existing diastema is to be
maintained in a planed fixed prosthesis.maintained in a planed fixed prosthesis.
 Consists of a loop on the lingual aspect of theConsists of a loop on the lingual aspect of the
prosthesis that connects adjacent retainer orprosthesis that connects adjacent retainer or
pontics.pontics.
 May be cast from a circular sprue wax or shapedMay be cast from a circular sprue wax or shaped
with platinum-gold-palladium alloy.with platinum-gold-palladium alloy.
 disadvantagedisadvantage
 Plaque control is a problem, so meticulous carePlaque control is a problem, so meticulous care
in designing should be there.in designing should be there.
Indications

SPLIT PONTICSPLIT PONTIC
•This is an attachment that is placed within the pontic.This is an attachment that is placed within the pontic.
• It is particularly useful in tilted abutment cases, where theIt is particularly useful in tilted abutment cases, where the
conventional dovetail would necessitate the drastic preparatio in theconventional dovetail would necessitate the drastic preparatio in the
distal aspect of the pier abutment.distal aspect of the pier abutment.
•Used in pier abutments.Used in pier abutments.
INDICATIONS:

ADVANTAGES:
1)When problem occurs only the affected segment can be removed and
repaired or remade.no need to remove the whole assembly.
2)Stresses that are to be applied are evenly distributed.
3)Aalows some degree of movement in function and hence protects the
abutment overloading.
4)Also act as a splint.
DISADVANTAGES:
1)More time consuming.
2)Cost factor.

Fabrication of wax pattern for split pontics:
The wax pattern for the anterior three-unit segment isThe wax pattern for the anterior three-unit segment is
fabricated first, with the distal arm attached to the pier relations.fabricated first, with the distal arm attached to the pier relations.
TheThe
underside of the arm is shaped like the tissue containity area ofunderside of the arm is shaped like the tissue containity area of
a pontic.a pontic. AA
surveyor is used to position either key and key way segmentsurveyor is used to position either key and key way segment
pointing occlusally and the segment must align with the distalpointing occlusally and the segment must align with the distal
abutment preparation.abutment preparation.

 Invest, burnout and cast the mesial third and a half unitInvest, burnout and cast the mesial third and a half unit
segment.segment.
 After preliminary finishing, seat the cast segment on theAfter preliminary finishing, seat the cast segment on the
working cast and place the plastic pattern down into it.working cast and place the plastic pattern down into it.
 Wax the distal retainers at distal occlusal two-third of theWax the distal retainers at distal occlusal two-third of the
pontic pattern.pontic pattern.
 The pontic can be metal-ceramic, but there should be a thinThe pontic can be metal-ceramic, but there should be a thin
collar of metal around the periphery of ceramic section.collar of metal around the periphery of ceramic section.
 Cement the mesial segment first followed by distal segmentCement the mesial segment first followed by distal segment..

CROSS PIN AND WING CONNECTORSCROSS PIN AND WING CONNECTORS ::
1)The design will be primarily used to accommodate the abutment teeth with1)The design will be primarily used to accommodate the abutment teeth with
disparate long axis.disparate long axis.
INDICATIONS:
2)Used in case of tilted molars.

Fabrication of connectorFabrication of connector ::
This is the working elements of a two-pieceThis is the working elements of a two-piece
pontic system that allows the two segments, topontic system that allows the two segments, to
be rigidly fixed after the retainer have beenbe rigidly fixed after the retainer have been
cemented on their respective abutmentcemented on their respective abutment
preparations.preparations.
The path of insertion of each toothThe path of insertion of each tooth
preparation is made to parallel the long axispreparation is made to parallel the long axis
of each tooth.of each tooth.
Attach a vertical wing, cut out of a piece ofAttach a vertical wing, cut out of a piece of
base palate wax, to the mesial surface ofbase palate wax, to the mesial surface of
the distal retainer wax pattern, the wingthe distal retainer wax pattern, the wing
should parallel the path of insertion of theshould parallel the path of insertion of the
mesial abutment preparation.mesial abutment preparation.

 Invest, burnout and seat the distal retainer. Seal it on the cast,Invest, burnout and seat the distal retainer. Seal it on the cast,
and drill 0.7 mm while through the wing with a twist drill.and drill 0.7 mm while through the wing with a twist drill.
 Plane 0.7 mm lead pencil through the hole and build the waxPlane 0.7 mm lead pencil through the hole and build the wax
pattern around the lead and the wing .Place 0.7 lead pencil inpattern around the lead and the wing .Place 0.7 lead pencil in
the pontic during investing so that the hole will be there in thethe pontic during investing so that the hole will be there in the
pontic.pontic.
 Assemble the two parts of the fixed partial denture on theAssemble the two parts of the fixed partial denture on the
working cast, use a reamer and smoothen the hole in theworking cast, use a reamer and smoothen the hole in the
pontic.pontic.
 Fabricate a pin of the same alloy used for fixed partial denture.Fabricate a pin of the same alloy used for fixed partial denture.
It must be long enough to extend all the wax throughout theIt must be long enough to extend all the wax throughout the
pontic cone assembly.pontic cone assembly.
 Try the pins for fit on the components on the cast.Try the pins for fit on the components on the cast.
 Cement the retainer with the wing first followed by the retainerCement the retainer with the wing first followed by the retainer
pontic segment.pontic segment.
 Seat the pin in the hole with a punch and mallett. Remove anySeat the pin in the hole with a punch and mallett. Remove any
excess length both facially and lingually.excess length both facially and lingually.www.indiandentalacademy.comwww.indiandentalacademy.com

ADVANTAGES:
1)NO NEED TO REMOVE THE WHOLE ASSEMBLY IF REQUIRED.
2)STRESS DISTRIBUTION.
3)FEDUCES THE AMT OF FORCE ON ABUTMENTS.
DISADVANTAGES:
1)TIME FACTOR.
2)ADDITIONAL LABORATORY STEPS REQUIRED FOR PIN FABRICATION.
3)TECHNIQUE SENSITIVE.

A LOCKING ROD AND TUBE CONNECTORA LOCKING ROD AND TUBE CONNECTOR
Ronald A Bryant, and Robert R,Faucher, (1983)Ronald A Bryant, and Robert R,Faucher, (1983)
Describes two methods for interlocking the segments of fixedDescribes two methods for interlocking the segments of fixed
splints.splints.
1.1. Solderless joints where the connector occurs betweenSolderless joints where the connector occurs between
adjacent abutment teeth .adjacent abutment teeth .

2) A locking rod and tube attachment when the connector occurs in a2) A locking rod and tube attachment when the connector occurs in a
Pontic space.Pontic space.
The locking rod and tube attachment allows complete independence ofThe locking rod and tube attachment allows complete independence of
each segment. If problems occur in any segment of the splint, onlyeach segment. If problems occur in any segment of the splint, only
that segment must be removed to make a repair.that segment must be removed to make a repair.
_

AN ALTERNATIVE ORIENTATION OF NONRIGIDAN ALTERNATIVE ORIENTATION OF NONRIGID
CONNECTORS IN FIXED PARTIAL DENTURESCONNECTORS IN FIXED PARTIAL DENTURES
Moulding MB., Holland GA., & Sulik WD. (1992)Moulding MB., Holland GA., & Sulik WD. (1992)
 Described an alternative orientation of nonrigid connectors in fixedDescribed an alternative orientation of nonrigid connectors in fixed
partial dentures to overcome space limitations which may requirepartial dentures to overcome space limitations which may require
overreduction of the preparation or overcontouring of the retainer tooverreduction of the preparation or overcontouring of the retainer to
place to keyway within the retainer wall .place to keyway within the retainer wall .
CONVENTIONAL ORIENTATIONwww.indiandentalacademy.comwww.indiandentalacademy.com

With this alternative orientation the key is attached to the distal surface of the mesialWith this alternative orientation the key is attached to the distal surface of the mesial
retainer in a dual abutment fixed partial dentures, and the keyway is incorporated inretainer in a dual abutment fixed partial dentures, and the keyway is incorporated in
the mesial surface of the pontic.the mesial surface of the pontic.
This alternative orientation of nonrigid connectors in FPDs has the followingThis alternative orientation of nonrigid connectors in FPDs has the following
advantages (1) conventional tooth abutment preparations with less reduction.advantages (1) conventional tooth abutment preparations with less reduction.
(2) Suitable axial contours, (3) Simplified angulation and placment of the nonrigid(2) Suitable axial contours, (3) Simplified angulation and placment of the nonrigid
connector with mesially inclined posterior abutment, and (4) Improved esthetics withconnector with mesially inclined posterior abutment, and (4) Improved esthetics with
porcelain.porcelain.
(ALTERNATIVE ORIENTATION)

SOLDERING: In soldering metal parts are joined together by melting a filler
Parrticle between them at a temperature below the solidus temperature of
Metal being joined and below 450°
BRAZING: IN BRAZING METAL PARTS ARE JOINED TOGETHER BY MELTING
A FILLER METAL BETWEEN THEM AT A TEMPERATURE BELOW THE SOLIDUS
TEMPERATUREOF THE METAL BEING JOINED AND ABOVE 450°
WELDING:IS THE PROCESS DURING WHICH A PORTION OF THE METAL BEING JOINED
IS MELTED AND FLOWED TOGETHER.
SOLDERING,BRAZING AND WELDING

MATERIAL SCIENCEMATERIAL SCIENCE ::
SOLDERSOLDER
TYPES :TYPES :
 ..According to Hardness :According to Hardness :
Soft solders eg. Lead tin alloys with a lowSoft solders eg. Lead tin alloys with a low
melting point.melting point.
Hard solders eg. Dental gold solders, silverHard solders eg. Dental gold solders, silver
solders.solders.
 ..According to Technique :According to Technique :
Free hand soldering ; used in assemblingFree hand soldering ; used in assembling
orthodontic and other assemblies.orthodontic and other assemblies.
Investment soldering ; used in bridges andInvestment soldering ; used in bridges and
restoration.restoration.

PRECERAMICPRECERAMIC SOLDERSSOLDERS :: are obviously high fusingare obviously high fusing
alloys, fusing only slightly beneath the softening point of thealloys, fusing only slightly beneath the softening point of the
parent alloy to be jointed.parent alloy to be jointed.
POSTCERAMIC SOLDERSPOSTCERAMIC SOLDERS flows below the pyroplastic rangeflows below the pyroplastic range
of the procelainof the procelain
Ideal solder should have the following qualitiesIdeal solder should have the following qualities ::
 Ease of flow at relatively low temperatures.Ease of flow at relatively low temperatures.
 Sufficient freely flow when melted (i.eSufficient freely flow when melted (i.e
phenomenon of wetting should be there).phenomenon of wetting should be there).
 Strength compatible with that of the structureStrength compatible with that of the structure
being soldered.being soldered.
 Acceptable donor to give an inconspicious joint.Acceptable donor to give an inconspicious joint.
 Resistance to tarnish and corrosion.Resistance to tarnish and corrosion.
 Resistance to pitting during heating andResistance to pitting during heating and
application.application.
 Low fusing than alloy.Low fusing than alloy.www.indiandentalacademy.comwww.indiandentalacademy.com

SOLDERING FLUXSOLDERING FLUX ::
This substance is applied to a metal surface to remove oxides or preventThis substance is applied to a metal surface to remove oxides or prevent
their formation. Then the solder is free to wet and spread over the cleantheir formation. Then the solder is free to wet and spread over the clean
metal surface.metal surface.
Fluxes are available in powder, liquid and paste forms. Flux formula isFluxes are available in powder, liquid and paste forms. Flux formula is
Borax glass (55 parts), basic acid (35 parts) and silica (10 parts).Borax glass (55 parts), basic acid (35 parts) and silica (10 parts).
Pastes are made by mixing powder with petrolatum. The petrolatumPastes are made by mixing powder with petrolatum. The petrolatum
excludes oxygen during heating and eventually carbonizes and thenexcludes oxygen during heating and eventually carbonizes and then
vaporizes. New fluxes are available for use with non-gold based alloys.vaporizes. New fluxes are available for use with non-gold based alloys.
All fluxes should kept away from contacting procelain otherwise, it mayAll fluxes should kept away from contacting procelain otherwise, it may
cause pitting and procelain discoloration may take place.cause pitting and procelain discoloration may take place.
SOLDERING ANTIFLUXSOLDERING ANTIFLUX ::
Antiflux is used to limit spreading of solder. When the metal surfaces isAntiflux is used to limit spreading of solder. When the metal surfaces is
clean, any excess solder introduced into work gap will tend to flow intoclean, any excess solder introduced into work gap will tend to flow into
unwanted areas. Graphite is often used as an antiflux. But the carbon easilyunwanted areas. Graphite is often used as an antiflux. But the carbon easily
evaporate at higher temperatures. A more reliable antiflux is iron oxide inevaporate at higher temperatures. A more reliable antiflux is iron oxide in
chloroform.chloroform. www.indiandentalacademy.comwww.indiandentalacademy.com

SOLDERING INVESTMENTSOLDERING INVESTMENT ::
Soldering investment are similar in composition to castingSoldering investment are similar in composition to casting
investments i.e. gypsum bonded and phosphate bonded.investments i.e. gypsum bonded and phosphate bonded.
Soldering investments should ideally contain fused quartz asSoldering investments should ideally contain fused quartz as
their refractory component to minimize expansion (thermal).their refractory component to minimize expansion (thermal).
HEAT SOURCEHEAT SOURCE ::
The heat source is a very important part of soldering. The mostThe heat source is a very important part of soldering. The most
commonly used heat source is gas –air as gas-oxygen torch.commonly used heat source is gas –air as gas-oxygen torch.
The flame must provide enough heat only to melt the fillerThe flame must provide enough heat only to melt the filler
metal, but also compensate for heat loss to the surroundings.metal, but also compensate for heat loss to the surroundings.
Thus the flame should not only have a high temperature, butThus the flame should not only have a high temperature, but
also a high heat content.also a high heat content.

The various gases areThe various gases are ::
 HydrogenHydrogen :: It has a lowest heat content (275It has a lowest heat content (275
Btu) and therefore heating would be slow. ThisBtu) and therefore heating would be slow. This
flame is not indicated for soldering of largeflame is not indicated for soldering of large
bridges.bridges.
 Natural gasNatural gas :: It has a temperature of 2680° andIt has a temperature of 2680° and
heat content which is four times that of hydrogenheat content which is four times that of hydrogen
(1000 Btu).(1000 Btu).
 AcetyleneAcetylene :: It has the highest flame temperatureIt has the highest flame temperature
(3140° C) and higher heat content than 1/2 of(3140° C) and higher heat content than 1/2 of
natural gas.natural gas.
Temperature from one part of its flameTemperature from one part of its flame
to another may vary by more thanto another may vary by more than
100°C.100°C.
Therefore positioning the torch is criticalTherefore positioning the torch is critical
and proper part of the flame must beand proper part of the flame must be
used.used.

SOLDERING TECHNIQUESSOLDERING TECHNIQUES ::
For metal ceramic fixed partial dentures the soldering ofFor metal ceramic fixed partial dentures the soldering of
connectors may be before the ceramic application, with a highconnectors may be before the ceramic application, with a high
fusing solder i.e. 1100°C (pre-ceramic solder) or after ceramicfusing solder i.e. 1100°C (pre-ceramic solder) or after ceramic
application with low fusing solder i.e . 750° C (post-ceramicapplication with low fusing solder i.e . 750° C (post-ceramic
solder).solder).
The different techniques are :The different techniques are :
a )Pre-ceramic solderinga )Pre-ceramic soldering c) Oven solderingc) Oven soldering
b) Post -ceramic solderingb) Post -ceramic soldering d)Torch solderingd)Torch soldering
 When evaluating the clinical work to determine whether cast orWhen evaluating the clinical work to determine whether cast or
soldered connectors give better results, 1) The determiningsoldered connectors give better results, 1) The determining
factor should be the fit the individual abutment castings. 2) Thisfactor should be the fit the individual abutment castings. 2) This
should be optimized throughout the investing and castingshould be optimized throughout the investing and casting
process to minimize the risk of incomplete seating.process to minimize the risk of incomplete seating.
In case of long span bridges, the problem is to obtain enoughIn case of long span bridges, the problem is to obtain enough
interabutment expansion without making the retainers toointerabutment expansion without making the retainers too
loose. So in such circumstances, a soldered connector mayloose. So in such circumstances, a soldered connector may
provide better accuracy.provide better accuracy.www.indiandentalacademy.comwww.indiandentalacademy.com

PROCEDUREPROCEDURE
ArmamentariumArmamentarium ::
Autopolymerizing acrylic resinAutopolymerizing acrylic resin
Zinc oxide- Eugenol pasteZinc oxide- Eugenol paste
Impression plasterImpression plaster
Mixing bowl and spatulaMixing bowl and spatula
Small brushSmall brush
Waxing instrumentWaxing instrument
Sticky wax, base plate wax, sprue waxSticky wax, base plate wax, sprue wax
Soldering investmentSoldering investment
Glass slabGlass slab
Soldering tripodSoldering tripod
FluxFlux
SolderSolder
TorchTorch
Pickling solution.Pickling solution.

..Occlusal Soldering IndexOcclusal Soldering Index ::

Grind the connector surfaces of the finished castings with a stone toGrind the connector surfaces of the finished castings with a stone to
remove the surface oxides. Then fully seat the castings on the workingremove the surface oxides. Then fully seat the castings on the working
cast or in the mouth. The soldering gap can be adjusted at 0.25mm.cast or in the mouth. The soldering gap can be adjusted at 0.25mm.
Make an impression plaster registration in a small tray or on aMake an impression plaster registration in a small tray or on a
sheet of base plate wax for the occlusal index. Index can be madesheet of base plate wax for the occlusal index. Index can be made
with ZOE paste.with ZOE paste.

The index should not cover the margins of regular gold retainers.The index should not cover the margins of regular gold retainers.
Trim the index to expose the margins fully prior to investing.Trim the index to expose the margins fully prior to investing.
Seat each casting into the index and lute it to place with sticky wax.Seat each casting into the index and lute it to place with sticky wax.
To create a space that will help the solder spread, adapt sprue gingival toTo create a space that will help the solder spread, adapt sprue gingival to
the solder joint.the solder joint.
Protect any glazed porcelain from contacting the investment by coating itProtect any glazed porcelain from contacting the investment by coating it
with wax before investing. Burying the units completely in the investmentwith wax before investing. Burying the units completely in the investment
makes soldering difficult, between the unnecessary bulk of themakes soldering difficult, between the unnecessary bulk of the
investment prevent rapid heating of the casting.investment prevent rapid heating of the casting.
..
Flow wax intp the connector area to prevent
The investment from entry.

 Box the assembly with a suitable sheet wax.Box the assembly with a suitable sheet wax.
 Mix the investment carefully and flow it into the castingsMix the investment carefully and flow it into the castings
without entrapping any air.without entrapping any air.
 Allow the invested block to bench set prior to removing theAllow the invested block to bench set prior to removing the
wax and preheating.wax and preheating.

When placing solder,avoid spattering flux on adjacent
Occlusal surfaces;solder can flow to fill occlusal surfaces.
Antifluxes can be used to restrict flow.
When melted, solder becomes shiny fluid that rapidly
Fills joint space after use of properly directed reducing
Flame.

EFFICIENT SOLDERING INDEXEFFICIENT SOLDERING INDEX
MATERIALS FOR FIXED PARTIALMATERIALS FOR FIXED PARTIAL
DENTURES AND IMPLANTDENTURES AND IMPLANT
SUBSTRUCTURESSUBSTRUCTURES
George CC, and Winston WL.(1995)George CC, and Winston WL.(1995)
Discussed that multiple-unit fixed partial dentures routinely requireDiscussed that multiple-unit fixed partial dentures routinely require
an intraoral index to ensure accurate fit. One of the most commonlyan intraoral index to ensure accurate fit. One of the most commonly
used materials is Duralay acrylic resin, which has yieldedused materials is Duralay acrylic resin, which has yielded
satisfactory clinical results, but one disadvantage has been asatisfactory clinical results, but one disadvantage has been a
prolonged setting time. This study compared the setting times of twoprolonged setting time. This study compared the setting times of two
auto polymerizing resins, Duralay and G.C.Pattern resin. Theauto polymerizing resins, Duralay and G.C.Pattern resin. The
dimensional accuracy of these materials was also compared withdimensional accuracy of these materials was also compared with
one light-cured resin. G.C.Unifast light-cure resin. All three materialsone light-cured resin. G.C.Unifast light-cure resin. All three materials
were suitable to relate castings with clinically acceptable outcomes,were suitable to relate castings with clinically acceptable outcomes,
and chairside time could be saved with the use of recentlyand chairside time could be saved with the use of recently
introduced indexing materials.introduced indexing materials.

AUTO POLYMERIZING RESIN SOLDERINGAUTO POLYMERIZING RESIN SOLDERING
INDEXINDEX
An occlusal index is less suitable for the registrationAn occlusal index is less suitable for the registration
of anterior restorations. The thinness of the incisalof anterior restorations. The thinness of the incisal
edges of these units makes them less stable.edges of these units makes them less stable.
STEPS :STEPS :
 Join the completed units together withJoin the completed units together with
autopolymerizing resin.autopolymerizing resin.
 The resin will later burnout, leaving no residue thatThe resin will later burnout, leaving no residue that
could interfere with the casting.could interfere with the casting.
 Apply the resin with a bead technique becauseApply the resin with a bead technique because
this will minimize distortion from polymerizationthis will minimize distortion from polymerization
shrinkage. The resin should extend out the incisalshrinkage. The resin should extend out the incisal
edges of the retainers and excessive bulk of resinedges of the retainers and excessive bulk of resin
reduces the accuracy of the technique.reduces the accuracy of the technique.

STEPSSTEPS ::
 When the resin has fully hardened, carefully loosenWhen the resin has fully hardened, carefully loosen
the prosthesis from the abutments and again checkthe prosthesis from the abutments and again check
for any distortion. Same way as we check the try-in offor any distortion. Same way as we check the try-in of
an FPD.an FPD.
 Warm a sheet of wax and push the cervical aspect ofWarm a sheet of wax and push the cervical aspect of
the restorations through it, and seal it along the axialthe restorations through it, and seal it along the axial
wall with a warm instrument.wall with a warm instrument.
 Fill the castings with soldering investment and blotFill the castings with soldering investment and blot
excess water from the investment forming it into aexcess water from the investment forming it into a
patty on a slab or tile.patty on a slab or tile.
 Seat the restorations on the patty.Seat the restorations on the patty.

COMPARISON OF ACCURACY OFCOMPARISON OF ACCURACY OF
SOLDERING INDICES FOR FIXEDSOLDERING INDICES FOR FIXED
PROSTHESESPROSTHESES
Moon PC Eshleman JR, et al., (1978),Moon PC Eshleman JR, et al., (1978),
Conducted a study to compare the accuracy of impressionConducted a study to compare the accuracy of impression
plaster with cold-curing acrylic resin indices in the transfer ofplaster with cold-curing acrylic resin indices in the transfer of
crowns from their abutment dies in preparation for the solderingcrowns from their abutment dies in preparation for the soldering
of fixed partial dentures.of fixed partial dentures.
Indices were made according to the methods described byIndices were made according to the methods described by
stackhouse and Patterson for plaster and acrylic resin indices,stackhouse and Patterson for plaster and acrylic resin indices,
respectively.respectively.
Tow variations in the technique of fabricating plaster indicesTow variations in the technique of fabricating plaster indices
were studied i e. plaster-removal and plaster-non-removal .were studied i e. plaster-removal and plaster-non-removal .
Tow sets of acrylic resin indices were made with Duralay resinTow sets of acrylic resin indices were made with Duralay resin
using 3mm and 6mm thickness.using 3mm and 6mm thickness.

The following variables were studied.The following variables were studied.
1)1) Removal versus non-removal of the castings from theRemoval versus non-removal of the castings from the
plaster indexplaster index
2)2) The thickness of the acrylic resin indexing material.The thickness of the acrylic resin indexing material.
3)3) The length of time elapsed after the index was made untilThe length of time elapsed after the index was made until
investing for soldering. Time intervals of hour and 24 hoursinvesting for soldering. Time intervals of hour and 24 hours
were used, and acrylic resin thickness of 3 mm and 6 mmwere used, and acrylic resin thickness of 3 mm and 6 mm
were evaluated.were evaluated.
AND THEY END WITH THE CONCLUSIONS THATAND THEY END WITH THE CONCLUSIONS THAT ::
1)1) The accuracy of plaster indices not vary significantly from 1The accuracy of plaster indices not vary significantly from 1
to 24 hours.to 24 hours.
2)2) The most accurate results are obtained with plaster indicesThe most accurate results are obtained with plaster indices
if the casings are not separated from the plaster beforeif the casings are not separated from the plaster before
stabilization with sticky wax.stabilization with sticky wax.
3)3) A Duralay soldering index 3 mm in thickness is significantlyA Duralay soldering index 3 mm in thickness is significantly
more accurate than one 6 mm in thickness.more accurate than one 6 mm in thickness.

A SOLDERING INDEX MADE WITH 4 META ADHESIVEA SOLDERING INDEX MADE WITH 4 META ADHESIVE
RESINRESIN
Jeffrey C., Thomass L., et al., (1994)Jeffrey C., Thomass L., et al., (1994)
 Discussed that soldering indexes are most oftenDiscussed that soldering indexes are most often
made of fast setting impression plaster ormade of fast setting impression plaster or
autopolymerizing resin. Lack of adhesiveautopolymerizing resin. Lack of adhesive
bonding between these materials and thebonding between these materials and the
castings requires the use of a bulky index tocastings requires the use of a bulky index to
support the fixed partial denture components.support the fixed partial denture components.
The advent of adhesive resins improves theThe advent of adhesive resins improves the
quality of the index and simplifies the procedure.quality of the index and simplifies the procedure.
This procedure is accurate, simple, and timeThis procedure is accurate, simple, and time
saving. It can be used isnide or outside thesaving. It can be used isnide or outside the
mouth, in prosthodontic or implant dentistry.mouth, in prosthodontic or implant dentistry.

WAX REMOVAL, AND PREHEATINGWAX REMOVAL, AND PREHEATING ::
If a plaster or zinc oxide eugenol index was used, remove itIf a plaster or zinc oxide eugenol index was used, remove it
after the investment has fully set. The wax can be removed usingafter the investment has fully set. The wax can be removed using
boiling water and the joint space should be free of investment.boiling water and the joint space should be free of investment.
In the joint space, flow a little flux while the soldering block is still warmIn the joint space, flow a little flux while the soldering block is still warm
from the wax removal so that it will prevent small particless falling intofrom the wax removal so that it will prevent small particless falling into
the gap.the gap.
WAX REMOVAL
APPLICATION OF FLUX
AND ANTILFLUX

Then pre heat the investment in a burnout furnace.Then pre heat the investment in a burnout furnace.
650°C (for low heat soldering)650°C (for low heat soldering)
850° C (for post ceramic soldering)850° C (for post ceramic soldering)
Acrylic resin indexes are removed by heating slowly to 300° CAcrylic resin indexes are removed by heating slowly to 300° C
at which time most of the resin will have burned away.at which time most of the resin will have burned away.
Heat the block to 650°C until all traces of wax and resinHeat the block to 650°C until all traces of wax and resin
have vaporized and then transfer it to the soldering stand.have vaporized and then transfer it to the soldering stand.

SOLDERING TECHIQUESOLDERING TECHIQUE ::
Once the metal casting are ready for soldering, depending on theOnce the metal casting are ready for soldering, depending on the
situation, and type of restoration, we have to decide, what type ofsituation, and type of restoration, we have to decide, what type of
soldering has to be done.soldering has to be done.
 Preceramic SolderingPreceramic Soldering ::
Here the soldering is done before ceramic application, with aHere the soldering is done before ceramic application, with a
high fusing solder.high fusing solder.
Advantage :Advantage :
 Allows the connected prosthesis to be tried in theAllows the connected prosthesis to be tried in the
mouth in the unglazed state and any adjustmentsmouth in the unglazed state and any adjustments
made in the procelain.made in the procelain.
Disadvantages :Disadvantages :
 When porcelain has to be applied to a longerWhen porcelain has to be applied to a longer
structures which if not supported will deform or sagstructures which if not supported will deform or sag
especially with the high gold alloys.especially with the high gold alloys.
 Difficult to contour the proximal embrasures.Difficult to contour the proximal embrasures.
 Volatalization of base metal solder occurs due to overVolatalization of base metal solder occurs due to over
heating, this will lead to microporosity or pitting.heating, this will lead to microporosity or pitting.
 The melting range is very narrow between silver andThe melting range is very narrow between silver and
copper is not added, if they are added, they discolorcopper is not added, if they are added, they discolor
porcelain on contact.porcelain on contact.

Post Ceramic SolderingPost Ceramic Soldering ::
 Necessary when regular gold and metal ceramic unitsNecessary when regular gold and metal ceramic units
are being combined in fixed partial denture. A postare being combined in fixed partial denture. A post
soldered connector can be made to look more naturalsoldered connector can be made to look more natural
since it is close after the proximal surface is shaped.since it is close after the proximal surface is shaped.
 Sagging will not be a problem.Sagging will not be a problem.
 Can be performed in a porcelain furnace or with gas-airCan be performed in a porcelain furnace or with gas-air
torch.torch.

POST-CERAMIC SOLDERING OFPOST-CERAMIC SOLDERING OF
VARIOUS ALLOYSVARIOUS ALLOYS
Sloan RM, Reisbick MH, and Preston JD.(1982)Sloan RM, Reisbick MH, and Preston JD.(1982)
Studied precious, semiprecious, and base metals and reportedStudied precious, semiprecious, and base metals and reported
joint strengths apparently satisfactory for intraoral use and alsojoint strengths apparently satisfactory for intraoral use and also
evaluated the criterion of one such solder joint that wasevaluated the criterion of one such solder joint that was
apparently satisfactory and they end up with the conclusion that.apparently satisfactory and they end up with the conclusion that.
1. Base metal alloys can be soldered to precious and semiprecious1. Base metal alloys can be soldered to precious and semiprecious
alloys using a post-ceramic gold soldering technique.alloys using a post-ceramic gold soldering technique.
2. Tensile strengths of the solder joints with the base metal alloys2. Tensile strengths of the solder joints with the base metal alloys
are comparable to the precious and semiprecious metals.are comparable to the precious and semiprecious metals.
3. Not all fiuxes are able to control the oxides formed by the base3. Not all fiuxes are able to control the oxides formed by the base
metal used.metal used.

SOLDERING PORECELAIN-FUSED-TO-METAL FIXEDSOLDERING PORECELAIN-FUSED-TO-METAL FIXED
PARTIAL DENTURESPARTIAL DENTURES
Hubert TC, James SB, (1973)Hubert TC, James SB, (1973)
Described a technique for soldering the segments of aDescribed a technique for soldering the segments of a
porcelain-fused-to-metal fixed partial denture that hasporcelain-fused-to-metal fixed partial denture that has
been sectioned after its initial fabrication.been sectioned after its initial fabrication.
ProcedureProcedure
1.1. Position the segments of the prosthesis in the mouth inPosition the segments of the prosthesis in the mouth in
the desired position using sticky wax in the connectorthe desired position using sticky wax in the connector
areas to stabilize the pontic span.areas to stabilize the pontic span.
2.2. Make a lingual or occlusal plaster index.Make a lingual or occlusal plaster index.
Fixed partial denture that has pontic area
Sectioned from its retainers.
Plaster indexwww.indiandentalacademy.comwww.indiandentalacademy.com

Remove the segments of the fixed partial denture from the index.Remove the segments of the fixed partial denture from the index.
Make two holes in the metal portion of the pontic adjacent to the areas to beMake two holes in the metal portion of the pontic adjacent to the areas to be
soldered with a No. ½ round bur. These holes should be 1.5 to 2 mm deep,soldered with a No. ½ round bur. These holes should be 1.5 to 2 mm deep,
slightly diveregnt, and placed as far gingivally as possible.slightly diveregnt, and placed as far gingivally as possible.
Form a staple that will insert into the preparedForm a staple that will insert into the prepared
holes using a precious-metal wire with aholes using a precious-metal wire with a
high melting temperature. The wire may nothigh melting temperature. The wire may not
fit tightly, but this causes no problem sincefit tightly, but this causes no problem since
the pontic will be stabilized with investmentthe pontic will be stabilized with investment
against its metal lingual section.against its metal lingual section.
Reposition all segments of the prosthesis in theReposition all segments of the prosthesis in the
plaster index. It may be necessary to trim awayplaster index. It may be necessary to trim away
portions of the plaster that interfere with the wireportions of the plaster that interfere with the wire
staple.staple.

5.5. Cover the porcelain, and fill the connector areas to beCover the porcelain, and fill the connector areas to be
soldered with a soft wax.soldered with a soft wax.
6.6. Invest the prosthesis in a refractory soldering investment,Invest the prosthesis in a refractory soldering investment,
and allow it to harden.and allow it to harden.
7.7. Remove the wax with hot water. This will leave spacesRemove the wax with hot water. This will leave spaces
around the porcelain veneer and the connector area to bearound the porcelain veneer and the connector area to be
soldered.soldered.
8.8. Place a very small amount of flux in the area to be solderedPlace a very small amount of flux in the area to be soldered
and around the area where the wire staple enters the ponticand around the area where the wire staple enters the pontic
span.span. www.indiandentalacademy.comwww.indiandentalacademy.com

11.11. Solder the connector areas and the junction of the wireSolder the connector areas and the junction of the wire
staple and pontic span with 650 fine-gold solder using astaple and pontic span with 650 fine-gold solder using a
gas-driven air torch or a porcelain furance. If the torchgas-driven air torch or a porcelain furance. If the torch
method of soldering is used, the prosthesis and refractorymethod of soldering is used, the prosthesis and refractory
investment should be carefully preheated in a furnace.investment should be carefully preheated in a furnace.
12.12. Slowly cool the prosthesis, remove the investment, andSlowly cool the prosthesis, remove the investment, and
clean it with a pickling solution.clean it with a pickling solution.

THE EFFECTS OF PREWETTING ONTHE EFFECTS OF PREWETTING ON
POSTSOLDERING OF BASE METALPOSTSOLDERING OF BASE METAL
ALLOYSALLOYS
Richard L B (1985)Richard L B (1985) Conducted a study to determine if strongConducted a study to determine if strong
predictable, oxide-free joints could be obtained when postpredictable, oxide-free joints could be obtained when post
soldering a base metal alloy and they end up with thesoldering a base metal alloy and they end up with the
conclusion that prewetting the surface of a base metal alloyconclusion that prewetting the surface of a base metal alloy
with solder prior to low temperature soldering producedwith solder prior to low temperature soldering produced
strong, predictable, oxide-free joints similar to precious metalstrong, predictable, oxide-free joints similar to precious metal
joints. The positive results were obtained whether the prewetjoints. The positive results were obtained whether the prewet
base metal was soldered to other prewet base metal or tobase metal was soldered to other prewet base metal or to
precious metals. Soldered combinations of non-prewet baseprecious metals. Soldered combinations of non-prewet base
metal showed lower strength, less predictability, and moremetal showed lower strength, less predictability, and more
oxide formation than the prewet counterparts.oxide formation than the prewet counterparts.

ACCURACY OF ONE-PIECE CASTINGS,ACCURACY OF ONE-PIECE CASTINGS,
PRECERAMIC AND POSTCERAMICPRECERAMIC AND POSTCERAMIC
SOLDERINGSOLDERING
Ziebert GJ, Hurtado A, et al., (1986)Ziebert GJ, Hurtado A, et al., (1986)
Conducted a study to compare the relative accuracy of theConducted a study to compare the relative accuracy of the
multiunit cast fixed partial dentures of varying lengths from themultiunit cast fixed partial dentures of varying lengths from the
study by Schiffleger et al. with those assembled by pre-andstudy by Schiffleger et al. with those assembled by pre-and
postceramic soldering.postceramic soldering.
Fifteen multiunit FPDs were cast in one piece ceramic alloy.Fifteen multiunit FPDs were cast in one piece ceramic alloy.
Five castings each consisted of three units, four units, and fiveFive castings each consisted of three units, four units, and five
units.units.
More 15 castings were sectioned through the connector areaMore 15 castings were sectioned through the connector area
each castings of three units, four units.each castings of three units, four units.
And it was concluded that .And it was concluded that .
1. Both preceramic and postceramic soldering adversely affected1. Both preceramic and postceramic soldering adversely affected
the marginal fit of the FPDs as demonstrated by the fact thatthe marginal fit of the FPDs as demonstrated by the fact that
the seating ability of the castings decreased as the span of thethe seating ability of the castings decreased as the span of the
prosthesis increased.prosthesis increased.www.indiandentalacademy.comwww.indiandentalacademy.com

2.2. Both preceramic and postcreamic soldering were equallyBoth preceramic and postcreamic soldering were equally
accurate.accurate.
3.3. The marginal fit of the three-unit FPDs cast as one piece wasThe marginal fit of the three-unit FPDs cast as one piece was
comparable with those assembled by preceramic andcomparable with those assembled by preceramic and
postcreamic sodlering.postcreamic sodlering.
4.4. The four-and five-unit FPDs that were assembled byThe four-and five-unit FPDs that were assembled by
preceramic and postecramic soldering fit significantly better atpreceramic and postecramic soldering fit significantly better at
the margins than those cast in one piece.the margins than those cast in one piece.

Oven soldering or Furnace Soldering :Oven soldering or Furnace Soldering :
 It is performed under vaccum or in air ; A piece of solder isIt is performed under vaccum or in air ; A piece of solder is
placed at the joint space and the casting and solder areplaced at the joint space and the casting and solder are
heated simultaneously.heated simultaneously.
 Less porosity resulted when castings were brought toLess porosity resulted when castings were brought to
soldering temperature before solder is applied.soldering temperature before solder is applied.
 This method does not allow movement of solder fusion.This method does not allow movement of solder fusion.
 The longer the solder remains molten, the more it willThe longer the solder remains molten, the more it will
dissolve the parent metal and thus weakens the joint.dissolve the parent metal and thus weakens the joint.
 Another technique is when horizontal muffle is used, thenAnother technique is when horizontal muffle is used, then
soldering assembly is heated above fusion point of solder,soldering assembly is heated above fusion point of solder,
muffle donor is opened and solder is fed into space.muffle donor is opened and solder is fed into space.

IV. TORCH SOLDERING :IV. TORCH SOLDERING :
 When torch is used to melt solder, metal ceramicWhen torch is used to melt solder, metal ceramic
restoration is preheated in the oven to avoidrestoration is preheated in the oven to avoid
cracking the porcelain.cracking the porcelain.
 Reducing zone of flame is used to prevent oxidationReducing zone of flame is used to prevent oxidation
of joint surfaces.of joint surfaces.
 The flame is kept moving to prevent uncover heatThe flame is kept moving to prevent uncover heat
distribution.distribution.
 During this procedure the flow of solder is controllableDuring this procedure the flow of solder is controllable
and used when connector has not been welland used when connector has not been well
designed in wax.designed in wax.

PROCEDUREPROCEDURE ::
 Transfer the assembly to a soldering stand with aTransfer the assembly to a soldering stand with a
Bunsen flame underneath and place a piece of solderBunsen flame underneath and place a piece of solder
above the gap. Adjust the gas air torch to give aabove the gap. Adjust the gas air torch to give a
sharp blue flame.sharp blue flame.
 The flame is directed at the lingual aspect of the blockThe flame is directed at the lingual aspect of the block
rather than at the casting.rather than at the casting.
 Heat evenly and slowly, moving the tip of the flameHeat evenly and slowly, moving the tip of the flame
consistently between in post ceramic applicationconsistently between in post ceramic application
soldering, because porcelain may easily crack.soldering, because porcelain may easily crack.

When the metal glows brightly, the solder will melt and flow into theWhen the metal glows brightly, the solder will melt and flow into the
joint space.joint space.
 Quickly move the frame to the facial, when the solderQuickly move the frame to the facial, when the solder
"spins" in the joint, remove the flame."spins" in the joint, remove the flame.
 Extinguish the flame and let the soldered prosthesisExtinguish the flame and let the soldered prosthesis
cool for 4-5 minutes before quenching.cool for 4-5 minutes before quenching.
Earlier quenching may lead to distortion where asEarlier quenching may lead to distortion where as
prolonged bench cooling increases the brittleness ofprolonged bench cooling increases the brittleness of
the joint.the joint.

TORCH VERSUS OVEN PRECERAMIC SOLDERING OFTORCH VERSUS OVEN PRECERAMIC SOLDERING OF
A NICKEL CHROMIUM ALLOYA NICKEL CHROMIUM ALLOY
John A Sobieralski., Thomas J. Prihoda et al.,John A Sobieralski., Thomas J. Prihoda et al.,
(1990)(1990)
 Compared the tensile strength of base metal solderCompared the tensile strength of base metal solder
joints presoldered with a gas oxygen torch to that ofjoints presoldered with a gas oxygen torch to that of
joints presoldered in a procelain oven under vacuum andjoints presoldered in a procelain oven under vacuum and
concluded that a strong consistent, void free preceramicconcluded that a strong consistent, void free preceramic
solder joint was produced between a nickel chromiumsolder joint was produced between a nickel chromium
base and gold solder by both torch and ovenbase and gold solder by both torch and oven
presoldering techniques; however, preceramic solderingpresoldering techniques; however, preceramic soldering
with a torch tended to result in a stronger bond.with a torch tended to result in a stronger bond.

INFRA RED SOLDERINGINFRA RED SOLDERING ::
This can be used for low fusing connector as well as for preceramicThis can be used for low fusing connector as well as for preceramic
soldered joints. Good accuracy is possible with the system andsoldered joints. Good accuracy is possible with the system and
joints have similar strength to conventional soldering.joints have similar strength to conventional soldering.
 Invest the assembly in the customary manner using appropriateInvest the assembly in the customary manner using appropriate
material.material.
 After wax elimination, position the assembly in the heat focus ofAfter wax elimination, position the assembly in the heat focus of
the soldering machine.the soldering machine.
A pointer is used to ensure proper positioning of the connector areaA pointer is used to ensure proper positioning of the connector area
relative to the heat source. The connectors area is fluxed and the solder isrelative to the heat source. The connectors area is fluxed and the solder is
positioned as described for oven soldering.positioned as described for oven soldering. Eye should be protected formEye should be protected form
injury. Once the complete connection has formed after the fusing point ofinjury. Once the complete connection has formed after the fusing point of
the solder is reached, the heat source is shut off and the assembly isthe solder is reached, the heat source is shut off and the assembly is
removed from the soldering platform.removed from the soldering platform.

 A study done byA study done by Gerard, Leon and MartinGerard, Leon and Martin on the fiton the fit
of fixed partial dentures joined by Infra red solderingof fixed partial dentures joined by Infra red soldering
(Publsih in JPD, 1992: Vol 68).(Publsih in JPD, 1992: Vol 68).
 Here the study was compared with one piece fixedHere the study was compared with one piece fixed
partial denture castings and individually cast crowns;partial denture castings and individually cast crowns;
and joined by infra red soldering.and joined by infra red soldering.
 Casting were seated on their respective dies, embededCasting were seated on their respective dies, embeded
in epoxy resin and sectioned.in epoxy resin and sectioned.
 Gap distance were measured at specified marginalGap distance were measured at specified marginal
sites and results showed that fit of infrared soldering.sites and results showed that fit of infrared soldering.
Fixed partial denture were significantly better than oneFixed partial denture were significantly better than one
piece casting.piece casting.
 The gap openings measured in all castings are withinThe gap openings measured in all castings are within
the range of clinical acceptability.the range of clinical acceptability.

FATIGUE LIFE OF PRECERAMIC SOLDERED ANDFATIGUE LIFE OF PRECERAMIC SOLDERED AND
POSTCERAMIC SOLDERED JOINTSPOSTCERAMIC SOLDERED JOINTS
Timothy J Butson et al., (1993)Timothy J Butson et al., (1993)
 Investigated the fatigue life (ie, the number of cycles of a givenInvestigated the fatigue life (ie, the number of cycles of a given
stress that can be sustained by a sample prior to catastrophicstress that can be sustained by a sample prior to catastrophic
failure) of metal ceramic soldering. One metal ceramic alloy wasfailure) of metal ceramic soldering. One metal ceramic alloy was
joined using four postceramic solders and one preceramic solder.joined using four postceramic solders and one preceramic solder.
All specimens received appropriate heat treatment simulatingAll specimens received appropriate heat treatment simulating
ceramic application although no porcelain was applied. Fiveceramic application although no porcelain was applied. Five
specimens were fabricated for each solder type, and a 35,000 psispecimens were fabricated for each solder type, and a 35,000 psi
(241.4 Mpa) fatigue stress was applied to each solder joint during(241.4 Mpa) fatigue stress was applied to each solder joint during
specimen testing. The test variable was the number of stress cyclesspecimen testing. The test variable was the number of stress cycles
required to fail each specimen. The postceramic solders exhibitedrequired to fail each specimen. The postceramic solders exhibited
significantly higher fatigue lives than did the preceramic solder.significantly higher fatigue lives than did the preceramic solder.
Scanning electron microscope analysis showed that the preceramicScanning electron microscope analysis showed that the preceramic
solder not only exhibited a larger grain size, but also showedsolder not only exhibited a larger grain size, but also showed
micropores between these grains.micropores between these grains.

THE FIT OF FIXED PARTIAL DENTURESTHE FIT OF FIXED PARTIAL DENTURES
JOINED BY INFRARED SOLDERINGJOINED BY INFRARED SOLDERING
Gerard Byrne, Leno W. Laub, (1992)Gerard Byrne, Leno W. Laub, (1992)
This study determined the accuracy of fit of three-unit fixed partialThis study determined the accuracy of fit of three-unit fixed partial
dentures joined by an infrared soldering technique compared withdentures joined by an infrared soldering technique compared with
one-piece fixed partial denture castings and individually castone-piece fixed partial denture castings and individually cast
crowns. Wax patterns of prepared Ivories teeth, maxillary leftcrowns. Wax patterns of prepared Ivories teeth, maxillary left
central incisor and maxillary left canine, were injection molded; acentral incisor and maxillary left canine, were injection molded; a
plastic rod was used as a pontic. One group of patterns was castplastic rod was used as a pontic. One group of patterns was cast
as one-piece dentures; the other group was sectioned in theas one-piece dentures; the other group was sectioned in the
connector area, cast individually, and then joined by infraredconnector area, cast individually, and then joined by infrared
soldering. Castings were seated on their respective dies,soldering. Castings were seated on their respective dies,
embedded in epoxy resin, and specified marginal sites measuredembedded in epoxy resin, and specified marginal sites measured
with a profile projector. Results showed that the fit of infrared-with a profile projector. Results showed that the fit of infrared-
soldered fixed partial dentures was significantly better than of one-soldered fixed partial dentures was significantly better than of one-
piece castings and was comparable with the fit of single crowns.piece castings and was comparable with the fit of single crowns.
The gap openings measured in all castings were within the rangeThe gap openings measured in all castings were within the range
of clinical acceptability.of clinical acceptability.

THE SEATING OF ONE-PIECE ANDTHE SEATING OF ONE-PIECE AND
SOLDERED FIXED PARTIALSOLDERED FIXED PARTIAL
DENTURESDENTURES
Anthony GG, and Stephen FR. (1989)Anthony GG, and Stephen FR. (1989)This laboratory study compared the seating of one-piece castingsThis laboratory study compared the seating of one-piece castings
with that of soldered fixed partial dentures. Two investmentswith that of soldered fixed partial dentures. Two investments
were investigated, five American Dental Association type III andwere investigated, five American Dental Association type III and
five metal ceramic alloy, fixed partial dentures were made by usingfive metal ceramic alloy, fixed partial dentures were made by using
the conventional indirect technique. The investing and castingthe conventional indirect technique. The investing and casting
protocol was designed to produce an ideal fit of the individualprotocol was designed to produce an ideal fit of the individual
complete crown abutments, not the fixed partial denture.complete crown abutments, not the fixed partial denture.
Independent seating of each retainer provided a baselineIndependent seating of each retainer provided a baseline
measurement for complete seating and was compared with fixedmeasurement for complete seating and was compared with fixed
partial denture seating. Fixed partial dentures were then sectionedpartial denture seating. Fixed partial dentures were then sectioned
and reassembled by soldering twice, using a low-and high-and reassembled by soldering twice, using a low-and high-
expansion investment. Marginal discrepancies with one-pieceexpansion investment. Marginal discrepancies with one-piece
casing and lower (0.6%) thermal-expansion soldering werecasing and lower (0.6%) thermal-expansion soldering were
clinically unacceptable. A clinically acceptable fit was obtainedclinically unacceptable. A clinically acceptable fit was obtained
with the higher (1%) thermal-expansion soldering investment.with the higher (1%) thermal-expansion soldering investment.www.indiandentalacademy.comwww.indiandentalacademy.com

CAST CONNECTORS : ANCAST CONNECTORS : AN
ALTERNATIVE TO SOLDERING BASEALTERNATIVE TO SOLDERING BASE
METAL ALLOYSMETAL ALLOYS
Fehling AW,Sansom BP, Meiser ET, (1986)Fehling AW,Sansom BP, Meiser ET, (1986)
Describes a solder less technique for correcting an unstable baseDescribes a solder less technique for correcting an unstable base
metal fixed partial denture framework. The technique ismetal fixed partial denture framework. The technique is
expedient, requires only a conventional armamentarium, andexpedient, requires only a conventional armamentarium, and
produces consistent results.produces consistent results.
TechniqueTechnique ::
Unstable fixed partial denture at
Try in stage.

Diagonally sectioned metal substructure.
Sectioned area enlarged for mechanical retention
Joining stabilized parts of substructure with
Autopolymerizing resin.
Verifying stability intraorally after acrylic resin
joint has set

Acrylic resin joint sprued
With wax.
Mechanically joined substructure after recovery
From investment.oxide appears as thin line at
Framework and connector interface.
Joined substructure rechecked for stability .
Oxide layer is invisible after finishing.

1.1. A soldering index made with 4-meta adhesive resin. J. Prosthet DentA soldering index made with 4-meta adhesive resin. J. Prosthet Dent
1994; 72 : 430-2.1994; 72 : 430-2.
2.2. Fatigue life of preceramic sodlered and postceramic soldered joints.Fatigue life of preceramic sodlered and postceramic soldered joints.
Int J Prosthodont 1993; 6 : 468-474.Int J Prosthodont 1993; 6 : 468-474.
3.3. Torch versus oven preceramic soldering of a nickel chromium alloy.Torch versus oven preceramic soldering of a nickel chromium alloy.
Quintessence Int 1993; 21 : 753-757.Quintessence Int 1993; 21 : 753-757.
4.4. An alternative orientation of nonrigid connectors in fixed partialAn alternative orientation of nonrigid connectors in fixed partial
dentures. J. Prosthet Dent 1992; 68 : 236-8.dentures. J. Prosthet Dent 1992; 68 : 236-8.
5.5. Post ceramic soldering of various alloys. J Prosthet Dent 1982; 48 :Post ceramic soldering of various alloys. J Prosthet Dent 1982; 48 :
686-689.686-689.
6.6. Efficient soldering index materials for fixed partial dentures andEfficient soldering index materials for fixed partial dentures and
implant substructures. J Prosthet Dent 1995; 73: 424-7.implant substructures. J Prosthet Dent 1995; 73: 424-7.
7.7. A locking rod and tube connector. J. Prosthet Dent 1993; 49 : 647-A locking rod and tube connector. J. Prosthet Dent 1993; 49 : 647-
651.651.
REFERENCESREFERENCES

8.8. The seating of one piece and soldered fixed partial dentures.The seating of one piece and soldered fixed partial dentures.
J Prosthet Dent 1989; 62: 292-7.J Prosthet Dent 1989; 62: 292-7.
9.9. Use of the split pontic nonrigid connector with the titlted molarUse of the split pontic nonrigid connector with the titlted molar
abutment. J. Prosthet Dent 1986; 36: 249-251.abutment. J. Prosthet Dent 1986; 36: 249-251.
10.10. The fit of fixed partial dentures joined by infrared soldering. JThe fit of fixed partial dentures joined by infrared soldering. J
Prosthet Dent 1992; 68: 591-6.Prosthet Dent 1992; 68: 591-6.
11.11. Cast connectors : An alternative to soldering base metalCast connectors : An alternative to soldering base metal
alloys. J. Prosthet Dent 1986; 55: 195-197.alloys. J. Prosthet Dent 1986; 55: 195-197.
12.12. Accuracy of one piece castings, preceramic and postceramicAccuracy of one piece castings, preceramic and postceramic
soldering. J. Prosthet Dent. 1986; 55: 312-317.soldering. J. Prosthet Dent. 1986; 55: 312-317.
13.13. The effects of prewetting on postsoldering of base metalThe effects of prewetting on postsoldering of base metal
alloys. J. Prosthet Dent. 1985; 54: 355-358.alloys. J. Prosthet Dent. 1985; 54: 355-358.
14.14. Soldering porcelain fused to metal fixed partial dentures. J.Soldering porcelain fused to metal fixed partial dentures. J.
Prosthet Dent. 1973; 30: 918-921.Prosthet Dent. 1973; 30: 918-921.
15.15. Comparison of accuracy of soldering indices for fixedComparison of accuracy of soldering indices for fixed
prostheses. J. Prosthet. Dent. 1978; 40: 35-38.prostheses. J. Prosthet. Dent. 1978; 40: 35-38.
16.16. Contemporary Fixed Prosthodontics . Rosensite 1Contemporary Fixed Prosthodontics . Rosensite 1stst
EditionEdition

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