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IMPRESSION TECHNIQUESIMPRESSION TECHNIQUES
FOR REMOVABLE PARTIALFOR REMOVABLE PARTIAL
DENTURE PROSTHESISDENTURE PROSTHESIS
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
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CONTENTSCONTENTS
• INTRODUCTIONINTRODUCTION
• DEFINITIONDEFINITION
• IMPRESSION TRAYSIMPRESSION TRAYS
• CLASSIFICATION OF IMPRESSION TECHNIQUESCLASSIFICATION OF IMPRESSION TECHNIQUES
• DIFFERENT FUNCTIONAL IMPRESSION PROCEDURESDIFFERENT FUNCTIONAL IMPRESSION PROCEDURES
• TECHNIQUES OF POURING THE ALTERED CASTTECHNIQUES OF POURING THE ALTERED CAST
• REVIEW OF LITERATUREREVIEW OF LITERATURE
• CONCLUSIONCONCLUSION
• BIBLIOGRAPHYBIBLIOGRAPHY
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ImpressionImpression
A negative likeness or copy in reverse of the surfaceA negative likeness or copy in reverse of the surface
of an object ; an imprint of teeth and adjacentof an object ; an imprint of teeth and adjacent
structures for use in dentistry.structures for use in dentistry.
GPT – 8GPT – 8
Partial denture impressionPartial denture impression
A negative likeness of a part or all of a partiallyA negative likeness of a part or all of a partially
edentulous archedentulous arch -- GPT – 8GPT – 8
Definitions
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An impression of partially edentulous archAn impression of partially edentulous arch
must record accurately the teeth inmust record accurately the teeth in anatomic formanatomic form
and surrounding tissues in aand surrounding tissues in a functional formfunctional form
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A receptacleA receptacle in to which suitable impression material isin to which suitable impression material is
placed to make negative likenessplaced to make negative likeness (or)(or) A device that is used toA device that is used to
carry, confine and control impression material while makingcarry, confine and control impression material while making
an impression.an impression.
Impression traysImpression trays
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Impression traysImpression trays can be classified broadly in to stock trays andcan be classified broadly in to stock trays and
custom trayscustom trays
Stock TraysStock Trays
Stock trays for partially edentulousStock trays for partially edentulous
patients may bepatients may be perforatedperforated to retainto retain
the impression material or they maythe impression material or they may
be constructed with abe constructed with a rimlockrimlock forfor
this purpose.this purpose.
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Another type of stock tray designed for theAnother type of stock tray designed for the
reversible type of hydrocolloid isreversible type of hydrocolloid is water cooled trayswater cooled trays. It. It
contains tubes through which water can be circulated forcontains tubes through which water can be circulated for
purpose of cooling the tray.purpose of cooling the tray.
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When stock tray is used 0.25 inch of impressionWhen stock tray is used 0.25 inch of impression
material is mandatory otherwise custom tray should be usedmaterial is mandatory otherwise custom tray should be used
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a. The peripheral borders may not bea. The peripheral borders may not be accuratelyaccurately recorded.recorded.
b. Considerablyb. Considerably more bulkiermore bulkier than a custom tray.than a custom tray.
Disadvantages: stock traysDisadvantages: stock trays
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a. Peripheral borders can bea. Peripheral borders can be preciselyprecisely
recorded in the impressionrecorded in the impression
b.b. ThicknessThickness of impression materialof impression material
can be controlled.can be controlled.
c.c. Custom trays are sometimes neededCustom trays are sometimes needed
for mouths that arefor mouths that are abnormally orabnormally or
of unusualof unusual configuration.configuration.
Custom impression trays:Custom impression trays:
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Impression
Materials
Non-elastic
Elastic
Aqueous
Hydrocolloids
Non-aqueous
Elastomers
Polysulfide
Silicones
Polyether
Condensation
Addition
Agar (reversible)
Alginate (irreversible)
Plaster
Compound
ZnO - Eugenol
Waxes
O’Brien Dental Materials & their Selection 1997
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Removable partial denture impression need to record theRemovable partial denture impression need to record the
teeth that are irregular in contour as well as varying in theirteeth that are irregular in contour as well as varying in their
vertical relations to occlusal plane.vertical relations to occlusal plane.
The chosen impression material must be capable of recordingThe chosen impression material must be capable of recording
the tissue contours as accurately as possible without distortion,the tissue contours as accurately as possible without distortion,
which occurs as impression is withdrawn.which occurs as impression is withdrawn.
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EdeEdentulous ridges will notntulous ridges will not
contribute to support of partialcontribute to support of partial
denture, because teeth absorbdenture, because teeth absorb
these forces before the forces arethese forces before the forces are
transmitted to the residual ridgetransmitted to the residual ridge
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Since the denture base does not contribute to support ofSince the denture base does not contribute to support of
the partial denture & the underlying mucosa and bone are notthe partial denture & the underlying mucosa and bone are not
subjected to functional forces, a tooth-supported removablesubjected to functional forces, a tooth-supported removable
partial denture can be constructed on a master cast made frompartial denture can be constructed on a master cast made from
a single, pressure-free impression that records the teeth & thea single, pressure-free impression that records the teeth & the
residual ridge in their anatomic formresidual ridge in their anatomic form
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when the design of a Removable partial denturewhen the design of a Removable partial denture
includes unilateral or bilateral distal extension denture base,includes unilateral or bilateral distal extension denture base,
no single impression procedure can record both the anatomicno single impression procedure can record both the anatomic
form of the teeth and the functional form of the residual ridge.form of the teeth and the functional form of the residual ridge.
Therefore some secondary or corrected impression methodTherefore some secondary or corrected impression method
must be needed.must be needed.
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• Steiger and Boitel (1959), the resiliency of the tissue fittingSteiger and Boitel (1959), the resiliency of the tissue fitting
surface of the denture base ranges from 0.4 to 2.0 mm,surface of the denture base ranges from 0.4 to 2.0 mm,
compared with the resiliency of 0.l mm for healthy periodontalcompared with the resiliency of 0.l mm for healthy periodontal
tissues.tissues.
• Tissue resiliency is therefore four to twenty times more thanTissue resiliency is therefore four to twenty times more than
the axial displace ability of the abutment tooth (Steiger andthe axial displace ability of the abutment tooth (Steiger and
Boitel, 1959).Boitel, 1959).
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The problem of achieving successful function of aThe problem of achieving successful function of a
Removable partial denture is equilibrating this resiliencyRemovable partial denture is equilibrating this resiliency
differential between the relatively non-resilient periodontaldifferential between the relatively non-resilient periodontal
ligament of the abutment tooth and the more resilient mucosaligament of the abutment tooth and the more resilient mucosa
covering the residual ridge.covering the residual ridge.
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The impression of residual ridge mustThe impression of residual ridge must
1.1. Record and relate the tissues under uniform loadingRecord and relate the tissues under uniform loading
2.2. Distribute the load over as large area as possibleDistribute the load over as large area as possible
3.3. Accurately delineate the peripheral extent of denture baseAccurately delineate the peripheral extent of denture base
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Factors influencing support of the distalFactors influencing support of the distal
extension baseextension base
• Quality of soft tissue covering edentulous ridgeQuality of soft tissue covering edentulous ridge
• Type of bone in the denture bearing areaType of bone in the denture bearing area
• Design of the prosthesisDesign of the prosthesis
• Amount of tissue coverage of denture baseAmount of tissue coverage of denture base
• Anatomy of the denture bearing areaAnatomy of the denture bearing area
• Fit of denture baseFit of denture base
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Objectives of dual impressionObjectives of dual impression
1) It records and relates the supporting tissues under uniform1) It records and relates the supporting tissues under uniform
loading.loading.
2) It distributes the load over as large area as possible.2) It distributes the load over as large area as possible.
3) Accurately delineate the peripheral extent of the denture base3) Accurately delineate the peripheral extent of the denture base
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Indications of dual impression technique.Indications of dual impression technique.
1.1. the distal extension ridge.the distal extension ridge.
2.2. long span anterior edentulous ridge normally including atlong span anterior edentulous ridge normally including at
least all the 6 anterior teeth.least all the 6 anterior teeth.
3.3. increased resiliency of the mucosaincreased resiliency of the mucosa
Test for determining the need for dual impression technique
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Impression techniquesImpression techniques
• Physiologic impression techniquePhysiologic impression technique
- McLean and Hindels method- McLean and Hindels method
- The functional relining method- The functional relining method
- The fluid wax method- The fluid wax method
• Selected pressure techniqueSelected pressure technique
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1.The Physiologic Or Functional Impression Technique:1.The Physiologic Or Functional Impression Technique:
This technique records the ridge position by placingThis technique records the ridge position by placing
an occlusal load on the impression tray as the impression isan occlusal load on the impression tray as the impression is
being made.being made.
 these techniques produced a generalized displacement of thethese techniques produced a generalized displacement of the
mucosa to a greater or lesser degree.mucosa to a greater or lesser degree.
 This displacement was intended to record the tissue in theThis displacement was intended to record the tissue in the
configuration it would assume when occlusal loading wasconfiguration it would assume when occlusal loading was
applied to a partial denture in function.applied to a partial denture in function.
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MCLEAN'S IMPRESSION TECHNIQUE:MCLEAN'S IMPRESSION TECHNIQUE:
They realized the need of recording the tissues of theThey realized the need of recording the tissues of the
residual ridge that would eventually support a distal extensionresidual ridge that would eventually support a distal extension
denture base in the functional, or supporting form and thendenture base in the functional, or supporting form and then
relating this functional impression to the remainder of the archrelating this functional impression to the remainder of the arch
by means of a second impression.by means of a second impression.
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DisadvantageDisadvantage
The greatest weakness of this technique was that fingerThe greatest weakness of this technique was that finger
pressure could not produce the same functional displacementpressure could not produce the same functional displacement
of the tissue that biting force produced.of the tissue that biting force produced.
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Hindel's modification ofHindel's modification of
Mcleans Technique:Mcleans Technique:
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DisadvantagesDisadvantages
a) If the action of the retentive clasps of the partial denturea) If the action of the retentive clasps of the partial denture isis
sufficient tosufficient to maintainmaintain the denture base in relation to the softthe denture base in relation to the soft
tissuestissues inin the displaced or functional form, interruption ofthe displaced or functional form, interruption of
blood circulation would ensure with possible adverse softblood circulation would ensure with possible adverse soft
tissue reactions and resorption of the underlying bone.tissue reactions and resorption of the underlying bone.
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b) If the action of the retentive clasps was not sufficient tob) If the action of the retentive clasps was not sufficient to
maintain that functional relationship of the denture base tomaintain that functional relationship of the denture base to
the soft tissue, the denture base will be occlusally positionedthe soft tissue, the denture base will be occlusally positioned
when the soft tissues are at rest.when the soft tissues are at rest.
this results in premature contact of the artificial teeth, whichthis results in premature contact of the artificial teeth, which
may be objectionable to many patients.may be objectionable to many patients.
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Functional Relining MethodFunctional Relining Method
• It consists of adding a new surface to the inner or tissue side ofIt consists of adding a new surface to the inner or tissue side of
the denture base.the denture base.
• The procedure may be accomplished before the insertion ofThe procedure may be accomplished before the insertion of
the partial denture, or it may be done later if the denture basethe partial denture, or it may be done later if the denture base
no longer fits the ridge adequately because of bone resorptionno longer fits the ridge adequately because of bone resorption
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procedureprocedure
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• During border molding the patient must maintain the mouth inDuring border molding the patient must maintain the mouth in
a partially open position while the border molding anda partially open position while the border molding and
impression are being accomplished because:impression are being accomplished because:
1. The border tissues, cheek, and tongue are thus best controlled .1. The border tissues, cheek, and tongue are thus best controlled .
2. The relationship between the partial denture framework and2. The relationship between the partial denture framework and
the teeth must be observed.the teeth must be observed.
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Making the final impressionMaking the final impression
1)Usually free flowing ZnO eugenol paste is used1)Usually free flowing ZnO eugenol paste is used
2)If undercuts are present on the ridge,light bodied2)If undercuts are present on the ridge,light bodied
polysulphide or silicone rubber may be usedpolysulphide or silicone rubber may be used
Functional reline method has the advantage that theFunctional reline method has the advantage that the
amount of soft tissue displacement can be controlled byamount of soft tissue displacement can be controlled by
amount of relief given to modeling plastic before makingamount of relief given to modeling plastic before making
final impression. Greater the relief,less will be the tissuefinal impression. Greater the relief,less will be the tissue
displacementdisplacement
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DisadvantageDisadvantage
1.1. The main problems that arise are caused by failure toThe main problems that arise are caused by failure to
maintain the correct relationship between the framework andmaintain the correct relationship between the framework and
the abutment.the abutment.
2.2. Failure to achieve accurate occlusal contact followingFailure to achieve accurate occlusal contact following
reline procedure.reline procedure.
3.3. As in all other reline procedures occlusal discrepancies mustAs in all other reline procedures occlusal discrepancies must
be correctedbe corrected
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Fluid Wax Functional ImpressionFluid Wax Functional Impression
TheThe objectivesobjectives of the technique are:-of the technique are:-
1.1. To obtain maximum extension of the peripheral borders of theTo obtain maximum extension of the peripheral borders of the
denture base while not interfering with the function ofdenture base while not interfering with the function of
movable border tissues.movable border tissues.
2.2. To record the stress-bearing areas of the ridge in theirTo record the stress-bearing areas of the ridge in their
functional form.functional form.
3.3. To record non-pressure-bearing areas in their anatomic form.To record non-pressure-bearing areas in their anatomic form.
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The term fluid wax is used to denote waxes that areThe term fluid wax is used to denote waxes that are
firm at room temperature and have the ability to flow at mouthfirm at room temperature and have the ability to flow at mouth
temperature.temperature.
• The most frequently used fluid waxes:The most frequently used fluid waxes:
Iowa WaxIowa Wax , developed by, developed by Dr. SmithDr. Smith
Korrecta WaxKorrecta Wax No.4, developed byNo.4, developed by Dr.O.CDr.O.C andand S.G.S.G.
ApplegateApplegate
• Korrecta Wax No.4 is slightly more fluid than Iowa Wax.Korrecta Wax No.4 is slightly more fluid than Iowa Wax.
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• The key to the use of fluid wax lies in two areas:The key to the use of fluid wax lies in two areas:
-- spacespace
- time- time
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• The borders must be short of all movable tissues, but not moreThe borders must be short of all movable tissues, but not more
than 2 mm short because the fluid wax does not have sufficientthan 2 mm short because the fluid wax does not have sufficient
strength to support itself beyond that distance.strength to support itself beyond that distance.
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Each time the tray is introduced into the mouth, it must remain inEach time the tray is introduced into the mouth, it must remain in
place 5 to 7 minutes.place 5 to 7 minutes.
- To allow the wax to flow and- To allow the wax to flow and
- To prevent buildup of pressure under the tray with- To prevent buildup of pressure under the tray with
resulting distortion or displacement of the tissue.resulting distortion or displacement of the tissue.
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procedureprocedure
1.1. Try in of frame work doneTry in of frame work done
2.2. Spacer adopted with use of base plate wax on castSpacer adopted with use of base plate wax on cast
3.3. Auto polymerising resin adapted and contoured over frameAuto polymerising resin adapted and contoured over frame
workwork
4.4. Excess material removedExcess material removed
5.5. Relief holes prepared along the crest of ridgeRelief holes prepared along the crest of ridge
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• the fluid wax taken from a water bath maintained at 51˚c tothe fluid wax taken from a water bath maintained at 51˚c to
54°C (125˚ to 130˚ F)54°C (125˚ to 130˚ F)
• At this temperature the wax becomes fluid.At this temperature the wax becomes fluid.
• The wax is painted on the tissue side of the impression trayThe wax is painted on the tissue side of the impression tray
with a brush.with a brush.
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• The impression surface which contacts the tissue will beThe impression surface which contacts the tissue will be
glossy and the surface which does not come in contact withglossy and the surface which does not come in contact with
the tissue will be dullthe tissue will be dull
• Wax is added on the dull surface and the impression is placedWax is added on the dull surface and the impression is placed
back for 5 min in the mouth .back for 5 min in the mouth .
• Procedure is repeated till the impression is completed.Procedure is repeated till the impression is completed.
The finished impression must be handled carefully, and theThe finished impression must be handled carefully, and the
new cast poured as soon as possible because the wax is fragilenew cast poured as soon as possible because the wax is fragile
and subject to distortion.and subject to distortion.
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• The fluid wax impression is made with the open mouthThe fluid wax impression is made with the open mouth
technique so that there is less danger of over-displacement oftechnique so that there is less danger of over-displacement of
ridge tissue by occlusal or vertical forces.ridge tissue by occlusal or vertical forces.
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DisadvantagesDisadvantages
• The procedure is time consuming.The procedure is time consuming.
• If the time periods are not followed accurately, thanIf the time periods are not followed accurately, than
impression with excessive tissue displacement will result.impression with excessive tissue displacement will result.
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Selected pressure impression techniqueSelected pressure impression technique
TheThe objectivesobjectives of the technique are:-of the technique are:-
1.1. the equalization of support between the abutment teeth and thethe equalization of support between the abutment teeth and the
soft tissuesoft tissue
2.2. To direct more force to those portions of the ridge which isTo direct more force to those portions of the ridge which is
able to absorb the stress without adverse response.able to absorb the stress without adverse response.
3.3. Protect the areas of the ridge which is least able to absorbProtect the areas of the ridge which is least able to absorb
force.force.
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Areas where relief is provided will be least displacedAreas where relief is provided will be least displaced
as the impression is recorded . In those areas of the tray whereas the impression is recorded . In those areas of the tray where
relief is not provided greater displacement of the underlyingrelief is not provided greater displacement of the underlying
mucosa will occurmucosa will occur
Mandibular Arch Posterior regionMandibular Arch Posterior region
1) Crest of Arch1) Crest of Arch
2)Buccal Shelf2)Buccal Shelf
3)Lingual slope – Principally resists horizontal or rotational3)Lingual slope – Principally resists horizontal or rotational
forces.forces.
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• The end result of this selected pressure impression is that theThe end result of this selected pressure impression is that the
denture base made impression will be closely adapted to anddenture base made impression will be closely adapted to and
in firm contact with the tissue covering the buccal shelf area ofin firm contact with the tissue covering the buccal shelf area of
the edentulous ridge.the edentulous ridge.
• The ridge crest on the other hand is lightly adapted to theThe ridge crest on the other hand is lightly adapted to the
tissue and the effects of occlusal loading will be less in thistissue and the effects of occlusal loading will be less in this
area.area.
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Techniques for pouring the corrected castTechniques for pouring the corrected cast
impressionimpression
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Procedure
1.1. Impression is received in the laboratory. Remove excess
impression material from the framework in areas that contact the
teeth.
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2. Trim the master cast so that the functional impression can be
poured in correct relationship to the remaining teeth.
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3. Seat the framework on the cast, and inspect it for contact
between the functional impression and the cast. If contact is
present, the cast must be trimmed until clearance is present.
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4. Cut retention grooves into the areas of the cast that will be
corrected when the functional impression is poured
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5. Adapt and seal beading wax 2 to 3 mm above the borders of
the functional impression
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6. Seat the framework on the cast, and secure it in position with
sticky wax
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7.7. Seal the leading edge of the impression to the cast to prevent
dental stone from flowing onto the teeth when the cast is
poured.
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8. Use strips of base plate wax to complete the boxing of the
impression on the buccal and lingual aspects
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9. A tight seal of beading and boxing wax is critical in this pouring
method and is difficult to attain. Test the completeness of the seal
by pouring clear slurry water into the boxed impression. A
difficult area to seal is the relief area under the major connector.
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10. Place the cast and impression in clear slurry water to soak for 4
to 5 minutes in preparation for pouring the corrected cast.
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11. Measure and mix the improved dental stone. Pour the boxed
impression by adding small increments of stone and using light
vibration. Sufficient stone must be used to support the heel of the
cast.
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12. Remove the boxing and luting materials from the corrected
cast. Shape the cast on a model trimmer.
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13. Soften the impression material in warm water, and remove13. Soften the impression material in warm water, and remove
the framework and impression tray from the corrected cast.the framework and impression tray from the corrected cast.
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14. Burn the impression tray off the framework and place it on
the cast. Smooth the land area of the cast, and the corrected
cast procedures is complete.
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Altered cast techniqueAltered cast technique
• Master cast must beMaster cast must be
modified in preparation formodified in preparation for
altered cast procedure.altered cast procedure.
Broken line indicatesBroken line indicates
proposed cast modificationsproposed cast modifications
for bilateral altered castfor bilateral altered cast
procedureprocedure
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• Master cast afterMaster cast after
modification, Dovetailsmodification, Dovetails
have been prepared tohave been prepared to
permit mechanicalpermit mechanical
interlocking of castinterlocking of cast
segmentssegments
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• Framework seated onFramework seated on
modified master cast andmodified master cast and
affixed using modellingaffixed using modelling
plastic to minimizeplastic to minimize
displacement and distortiondisplacement and distortion
Assembly is inverted inAssembly is inverted in
preparation for rimming andpreparation for rimming and
boxing proceduresboxing procedures
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• Utility wax is used to rimUtility wax is used to rim
the impression.it is locatedthe impression.it is located
2-3 mm from impression2-3 mm from impression
and 3-4mm peripherally.and 3-4mm peripherally.
Boxing wax added to form aBoxing wax added to form a
watertight vertical wall .watertight vertical wall .
Freshly mixed dental stoneFreshly mixed dental stone
is then introducedis then introduced
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• After the stone has gainedAfter the stone has gained
sufficient strength ,thesufficient strength ,the
corrected cast is recoveredcorrected cast is recovered
and trimmedand trimmed
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Review of literatureReview of literature
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The altered cast impression technique revisitedThe altered cast impression technique revisited
JADA, vol. 130, october 1999; 14;77JADA, vol. 130, october 1999; 14;77
Preoperative figure displaying
knife-edge residual ridge with
moderate-to-severe resorption.
final impression made in a border
molded acrylic resin tray that has
been attached to the latticework of
the cast framework.
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Complete seating of the framework
on the cast is essential before it is
fixed in place with sticky wax.
Note the placement of saw cuts and
retention slots
Before being poured, the final
impression is beaded and boxed
in the usual manner
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The final working altered cast.
Occlusal view of a well-fitting,
properly adapted removable
partial denture.
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Although there is some clinical evidence that the alteredAlthough there is some clinical evidence that the altered
cast impression procedure decreases the load on thecast impression procedure decreases the load on the
abutments. The altered cast impression procedure does notabutments. The altered cast impression procedure does not
offer significant advantages over the one piece castoffer significant advantages over the one piece cast
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SINGLE- TRAY DUAL- IMPRESSION TECHNIQUE FORSINGLE- TRAY DUAL- IMPRESSION TECHNIQUE FOR
DISTAL EXTENSION PARTIAL DENTURESDISTAL EXTENSION PARTIAL DENTURES
JOSEPH A. R- JPD 1970(24,1,41-46)JOSEPH A. R- JPD 1970(24,1,41-46)
• This technique is basedThis technique is based
philosophically onphilosophically on
Hindel’s loadHindel’s load
distribution principledistribution principle
• Records the ridgesRecords the ridges
dynamically anddynamically and
remaining teethremaining teeth
staticallystatically
• This techniqueThis technique
produces less bulkyproduces less bulky
final impressionfinal impression
www.indiandentalacademy.comwww.indiandentalacademy.com
conclusionconclusion
““ Good technique pays off ” is not merely a motto to hang on a
wall but these are words of wisdom. Good technique will
indeed result in better treatment and improved patient care.
www.indiandentalacademy.comwww.indiandentalacademy.com
BIBLIOGRAPHYBIBLIOGRAPHY
1. Glossary of Prosthodontic Terms -8 th Edn, 2005.1. Glossary of Prosthodontic Terms -8 th Edn, 2005.
2. Stewart, Rudd, Kuebker : Clinical Removable Partial2. Stewart, Rudd, Kuebker : Clinical Removable Partial
Prosthodontics.Prosthodontics.
3. Kenneth D Rudd, Morrow: Dental Lab, Procedure for3. Kenneth D Rudd, Morrow: Dental Lab, Procedure for
Removable Partial Dentures.Removable Partial Dentures.
4. McCracken’s : Removable Partial Prosthodontics -4. McCracken’s : Removable Partial Prosthodontics -
11 edition11 edition
www.indiandentalacademy.comwww.indiandentalacademy.com
5. J c davenport ; A colour atlas of removable partial dentures.5. J c davenport ; A colour atlas of removable partial dentures.
6. James s brudwik : Advanced removable partial denture6. James s brudwik : Advanced removable partial denture
7. John Osborne : partial dentures, iv edition7. John Osborne : partial dentures, iv edition
www.indiandentalacademy.comwww.indiandentalacademy.com
8. The altered cast impression technique revisited
JADA, vol. 130, october 1999; 14;77
9. An altered cast procedure to improve tissue support for
removable partial dentures
jpd 1994(15), 4, 672- 678
10.single- tray dual- impression technique for distal
extension partial dentures.
Journal of prosthet dent 1970(24,1,41-46)
11. Selective pressure single impression technique for
removable partial denture
Journal of prosthet dent 1998 ; 80; 2; 259
www.indiandentalacademy.comwww.indiandentalacademy.com
www.indiandentalacademy.comwww.indiandentalacademy.com

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Impression techniques for rpd raju/ oral surgery courses

  • 1. IMPRESSION TECHNIQUESIMPRESSION TECHNIQUES FOR REMOVABLE PARTIALFOR REMOVABLE PARTIAL DENTURE PROSTHESISDENTURE PROSTHESIS INDIAN DENTAL ACADEMY Leader in continuing Dental Education www.indiandentalacademy.comwww.indiandentalacademy.com
  • 2. CONTENTSCONTENTS • INTRODUCTIONINTRODUCTION • DEFINITIONDEFINITION • IMPRESSION TRAYSIMPRESSION TRAYS • CLASSIFICATION OF IMPRESSION TECHNIQUESCLASSIFICATION OF IMPRESSION TECHNIQUES • DIFFERENT FUNCTIONAL IMPRESSION PROCEDURESDIFFERENT FUNCTIONAL IMPRESSION PROCEDURES • TECHNIQUES OF POURING THE ALTERED CASTTECHNIQUES OF POURING THE ALTERED CAST • REVIEW OF LITERATUREREVIEW OF LITERATURE • CONCLUSIONCONCLUSION • BIBLIOGRAPHYBIBLIOGRAPHY www.indiandentalacademy.comwww.indiandentalacademy.com
  • 3. ImpressionImpression A negative likeness or copy in reverse of the surfaceA negative likeness or copy in reverse of the surface of an object ; an imprint of teeth and adjacentof an object ; an imprint of teeth and adjacent structures for use in dentistry.structures for use in dentistry. GPT – 8GPT – 8 Partial denture impressionPartial denture impression A negative likeness of a part or all of a partiallyA negative likeness of a part or all of a partially edentulous archedentulous arch -- GPT – 8GPT – 8 Definitions www.indiandentalacademy.comwww.indiandentalacademy.com
  • 4. An impression of partially edentulous archAn impression of partially edentulous arch must record accurately the teeth inmust record accurately the teeth in anatomic formanatomic form and surrounding tissues in aand surrounding tissues in a functional formfunctional form www.indiandentalacademy.comwww.indiandentalacademy.com
  • 5. A receptacleA receptacle in to which suitable impression material isin to which suitable impression material is placed to make negative likenessplaced to make negative likeness (or)(or) A device that is used toA device that is used to carry, confine and control impression material while makingcarry, confine and control impression material while making an impression.an impression. Impression traysImpression trays www.indiandentalacademy.comwww.indiandentalacademy.com
  • 7. Impression traysImpression trays can be classified broadly in to stock trays andcan be classified broadly in to stock trays and custom trayscustom trays Stock TraysStock Trays Stock trays for partially edentulousStock trays for partially edentulous patients may bepatients may be perforatedperforated to retainto retain the impression material or they maythe impression material or they may be constructed with abe constructed with a rimlockrimlock forfor this purpose.this purpose. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 8. Another type of stock tray designed for theAnother type of stock tray designed for the reversible type of hydrocolloid isreversible type of hydrocolloid is water cooled trayswater cooled trays. It. It contains tubes through which water can be circulated forcontains tubes through which water can be circulated for purpose of cooling the tray.purpose of cooling the tray. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 9. When stock tray is used 0.25 inch of impressionWhen stock tray is used 0.25 inch of impression material is mandatory otherwise custom tray should be usedmaterial is mandatory otherwise custom tray should be used www.indiandentalacademy.comwww.indiandentalacademy.com
  • 10. a. The peripheral borders may not bea. The peripheral borders may not be accuratelyaccurately recorded.recorded. b. Considerablyb. Considerably more bulkiermore bulkier than a custom tray.than a custom tray. Disadvantages: stock traysDisadvantages: stock trays www.indiandentalacademy.comwww.indiandentalacademy.com
  • 11. a. Peripheral borders can bea. Peripheral borders can be preciselyprecisely recorded in the impressionrecorded in the impression b.b. ThicknessThickness of impression materialof impression material can be controlled.can be controlled. c.c. Custom trays are sometimes neededCustom trays are sometimes needed for mouths that arefor mouths that are abnormally orabnormally or of unusualof unusual configuration.configuration. Custom impression trays:Custom impression trays: www.indiandentalacademy.comwww.indiandentalacademy.com
  • 13. Removable partial denture impression need to record theRemovable partial denture impression need to record the teeth that are irregular in contour as well as varying in theirteeth that are irregular in contour as well as varying in their vertical relations to occlusal plane.vertical relations to occlusal plane. The chosen impression material must be capable of recordingThe chosen impression material must be capable of recording the tissue contours as accurately as possible without distortion,the tissue contours as accurately as possible without distortion, which occurs as impression is withdrawn.which occurs as impression is withdrawn. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 14. EdeEdentulous ridges will notntulous ridges will not contribute to support of partialcontribute to support of partial denture, because teeth absorbdenture, because teeth absorb these forces before the forces arethese forces before the forces are transmitted to the residual ridgetransmitted to the residual ridge www.indiandentalacademy.comwww.indiandentalacademy.com
  • 15. Since the denture base does not contribute to support ofSince the denture base does not contribute to support of the partial denture & the underlying mucosa and bone are notthe partial denture & the underlying mucosa and bone are not subjected to functional forces, a tooth-supported removablesubjected to functional forces, a tooth-supported removable partial denture can be constructed on a master cast made frompartial denture can be constructed on a master cast made from a single, pressure-free impression that records the teeth & thea single, pressure-free impression that records the teeth & the residual ridge in their anatomic formresidual ridge in their anatomic form www.indiandentalacademy.comwww.indiandentalacademy.com
  • 16. when the design of a Removable partial denturewhen the design of a Removable partial denture includes unilateral or bilateral distal extension denture base,includes unilateral or bilateral distal extension denture base, no single impression procedure can record both the anatomicno single impression procedure can record both the anatomic form of the teeth and the functional form of the residual ridge.form of the teeth and the functional form of the residual ridge. Therefore some secondary or corrected impression methodTherefore some secondary or corrected impression method must be needed.must be needed. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 17. • Steiger and Boitel (1959), the resiliency of the tissue fittingSteiger and Boitel (1959), the resiliency of the tissue fitting surface of the denture base ranges from 0.4 to 2.0 mm,surface of the denture base ranges from 0.4 to 2.0 mm, compared with the resiliency of 0.l mm for healthy periodontalcompared with the resiliency of 0.l mm for healthy periodontal tissues.tissues. • Tissue resiliency is therefore four to twenty times more thanTissue resiliency is therefore four to twenty times more than the axial displace ability of the abutment tooth (Steiger andthe axial displace ability of the abutment tooth (Steiger and Boitel, 1959).Boitel, 1959). www.indiandentalacademy.comwww.indiandentalacademy.com
  • 18. The problem of achieving successful function of aThe problem of achieving successful function of a Removable partial denture is equilibrating this resiliencyRemovable partial denture is equilibrating this resiliency differential between the relatively non-resilient periodontaldifferential between the relatively non-resilient periodontal ligament of the abutment tooth and the more resilient mucosaligament of the abutment tooth and the more resilient mucosa covering the residual ridge.covering the residual ridge. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 19. The impression of residual ridge mustThe impression of residual ridge must 1.1. Record and relate the tissues under uniform loadingRecord and relate the tissues under uniform loading 2.2. Distribute the load over as large area as possibleDistribute the load over as large area as possible 3.3. Accurately delineate the peripheral extent of denture baseAccurately delineate the peripheral extent of denture base www.indiandentalacademy.comwww.indiandentalacademy.com
  • 20. Factors influencing support of the distalFactors influencing support of the distal extension baseextension base • Quality of soft tissue covering edentulous ridgeQuality of soft tissue covering edentulous ridge • Type of bone in the denture bearing areaType of bone in the denture bearing area • Design of the prosthesisDesign of the prosthesis • Amount of tissue coverage of denture baseAmount of tissue coverage of denture base • Anatomy of the denture bearing areaAnatomy of the denture bearing area • Fit of denture baseFit of denture base www.indiandentalacademy.comwww.indiandentalacademy.com
  • 21. Objectives of dual impressionObjectives of dual impression 1) It records and relates the supporting tissues under uniform1) It records and relates the supporting tissues under uniform loading.loading. 2) It distributes the load over as large area as possible.2) It distributes the load over as large area as possible. 3) Accurately delineate the peripheral extent of the denture base3) Accurately delineate the peripheral extent of the denture base www.indiandentalacademy.comwww.indiandentalacademy.com
  • 22. Indications of dual impression technique.Indications of dual impression technique. 1.1. the distal extension ridge.the distal extension ridge. 2.2. long span anterior edentulous ridge normally including atlong span anterior edentulous ridge normally including at least all the 6 anterior teeth.least all the 6 anterior teeth. 3.3. increased resiliency of the mucosaincreased resiliency of the mucosa Test for determining the need for dual impression technique www.indiandentalacademy.comwww.indiandentalacademy.com
  • 23. Impression techniquesImpression techniques • Physiologic impression techniquePhysiologic impression technique - McLean and Hindels method- McLean and Hindels method - The functional relining method- The functional relining method - The fluid wax method- The fluid wax method • Selected pressure techniqueSelected pressure technique www.indiandentalacademy.comwww.indiandentalacademy.com
  • 24. 1.The Physiologic Or Functional Impression Technique:1.The Physiologic Or Functional Impression Technique: This technique records the ridge position by placingThis technique records the ridge position by placing an occlusal load on the impression tray as the impression isan occlusal load on the impression tray as the impression is being made.being made.  these techniques produced a generalized displacement of thethese techniques produced a generalized displacement of the mucosa to a greater or lesser degree.mucosa to a greater or lesser degree.  This displacement was intended to record the tissue in theThis displacement was intended to record the tissue in the configuration it would assume when occlusal loading wasconfiguration it would assume when occlusal loading was applied to a partial denture in function.applied to a partial denture in function. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 25. MCLEAN'S IMPRESSION TECHNIQUE:MCLEAN'S IMPRESSION TECHNIQUE: They realized the need of recording the tissues of theThey realized the need of recording the tissues of the residual ridge that would eventually support a distal extensionresidual ridge that would eventually support a distal extension denture base in the functional, or supporting form and thendenture base in the functional, or supporting form and then relating this functional impression to the remainder of the archrelating this functional impression to the remainder of the arch by means of a second impression.by means of a second impression. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 27. DisadvantageDisadvantage The greatest weakness of this technique was that fingerThe greatest weakness of this technique was that finger pressure could not produce the same functional displacementpressure could not produce the same functional displacement of the tissue that biting force produced.of the tissue that biting force produced. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 28. Hindel's modification ofHindel's modification of Mcleans Technique:Mcleans Technique: www.indiandentalacademy.comwww.indiandentalacademy.com
  • 29. DisadvantagesDisadvantages a) If the action of the retentive clasps of the partial denturea) If the action of the retentive clasps of the partial denture isis sufficient tosufficient to maintainmaintain the denture base in relation to the softthe denture base in relation to the soft tissuestissues inin the displaced or functional form, interruption ofthe displaced or functional form, interruption of blood circulation would ensure with possible adverse softblood circulation would ensure with possible adverse soft tissue reactions and resorption of the underlying bone.tissue reactions and resorption of the underlying bone. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 30. b) If the action of the retentive clasps was not sufficient tob) If the action of the retentive clasps was not sufficient to maintain that functional relationship of the denture base tomaintain that functional relationship of the denture base to the soft tissue, the denture base will be occlusally positionedthe soft tissue, the denture base will be occlusally positioned when the soft tissues are at rest.when the soft tissues are at rest. this results in premature contact of the artificial teeth, whichthis results in premature contact of the artificial teeth, which may be objectionable to many patients.may be objectionable to many patients. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 31. Functional Relining MethodFunctional Relining Method • It consists of adding a new surface to the inner or tissue side ofIt consists of adding a new surface to the inner or tissue side of the denture base.the denture base. • The procedure may be accomplished before the insertion ofThe procedure may be accomplished before the insertion of the partial denture, or it may be done later if the denture basethe partial denture, or it may be done later if the denture base no longer fits the ridge adequately because of bone resorptionno longer fits the ridge adequately because of bone resorption www.indiandentalacademy.comwww.indiandentalacademy.com
  • 34. • During border molding the patient must maintain the mouth inDuring border molding the patient must maintain the mouth in a partially open position while the border molding anda partially open position while the border molding and impression are being accomplished because:impression are being accomplished because: 1. The border tissues, cheek, and tongue are thus best controlled .1. The border tissues, cheek, and tongue are thus best controlled . 2. The relationship between the partial denture framework and2. The relationship between the partial denture framework and the teeth must be observed.the teeth must be observed. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 35. Making the final impressionMaking the final impression 1)Usually free flowing ZnO eugenol paste is used1)Usually free flowing ZnO eugenol paste is used 2)If undercuts are present on the ridge,light bodied2)If undercuts are present on the ridge,light bodied polysulphide or silicone rubber may be usedpolysulphide or silicone rubber may be used Functional reline method has the advantage that theFunctional reline method has the advantage that the amount of soft tissue displacement can be controlled byamount of soft tissue displacement can be controlled by amount of relief given to modeling plastic before makingamount of relief given to modeling plastic before making final impression. Greater the relief,less will be the tissuefinal impression. Greater the relief,less will be the tissue displacementdisplacement www.indiandentalacademy.comwww.indiandentalacademy.com
  • 36. DisadvantageDisadvantage 1.1. The main problems that arise are caused by failure toThe main problems that arise are caused by failure to maintain the correct relationship between the framework andmaintain the correct relationship between the framework and the abutment.the abutment. 2.2. Failure to achieve accurate occlusal contact followingFailure to achieve accurate occlusal contact following reline procedure.reline procedure. 3.3. As in all other reline procedures occlusal discrepancies mustAs in all other reline procedures occlusal discrepancies must be correctedbe corrected www.indiandentalacademy.comwww.indiandentalacademy.com
  • 37. Fluid Wax Functional ImpressionFluid Wax Functional Impression TheThe objectivesobjectives of the technique are:-of the technique are:- 1.1. To obtain maximum extension of the peripheral borders of theTo obtain maximum extension of the peripheral borders of the denture base while not interfering with the function ofdenture base while not interfering with the function of movable border tissues.movable border tissues. 2.2. To record the stress-bearing areas of the ridge in theirTo record the stress-bearing areas of the ridge in their functional form.functional form. 3.3. To record non-pressure-bearing areas in their anatomic form.To record non-pressure-bearing areas in their anatomic form. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 38. The term fluid wax is used to denote waxes that areThe term fluid wax is used to denote waxes that are firm at room temperature and have the ability to flow at mouthfirm at room temperature and have the ability to flow at mouth temperature.temperature. • The most frequently used fluid waxes:The most frequently used fluid waxes: Iowa WaxIowa Wax , developed by, developed by Dr. SmithDr. Smith Korrecta WaxKorrecta Wax No.4, developed byNo.4, developed by Dr.O.CDr.O.C andand S.G.S.G. ApplegateApplegate • Korrecta Wax No.4 is slightly more fluid than Iowa Wax.Korrecta Wax No.4 is slightly more fluid than Iowa Wax. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 39. • The key to the use of fluid wax lies in two areas:The key to the use of fluid wax lies in two areas: -- spacespace - time- time www.indiandentalacademy.comwww.indiandentalacademy.com
  • 40. • The borders must be short of all movable tissues, but not moreThe borders must be short of all movable tissues, but not more than 2 mm short because the fluid wax does not have sufficientthan 2 mm short because the fluid wax does not have sufficient strength to support itself beyond that distance.strength to support itself beyond that distance. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 41. Each time the tray is introduced into the mouth, it must remain inEach time the tray is introduced into the mouth, it must remain in place 5 to 7 minutes.place 5 to 7 minutes. - To allow the wax to flow and- To allow the wax to flow and - To prevent buildup of pressure under the tray with- To prevent buildup of pressure under the tray with resulting distortion or displacement of the tissue.resulting distortion or displacement of the tissue. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 42. procedureprocedure 1.1. Try in of frame work doneTry in of frame work done 2.2. Spacer adopted with use of base plate wax on castSpacer adopted with use of base plate wax on cast 3.3. Auto polymerising resin adapted and contoured over frameAuto polymerising resin adapted and contoured over frame workwork 4.4. Excess material removedExcess material removed 5.5. Relief holes prepared along the crest of ridgeRelief holes prepared along the crest of ridge www.indiandentalacademy.comwww.indiandentalacademy.com
  • 43. • the fluid wax taken from a water bath maintained at 51˚c tothe fluid wax taken from a water bath maintained at 51˚c to 54°C (125˚ to 130˚ F)54°C (125˚ to 130˚ F) • At this temperature the wax becomes fluid.At this temperature the wax becomes fluid. • The wax is painted on the tissue side of the impression trayThe wax is painted on the tissue side of the impression tray with a brush.with a brush. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 45. • The impression surface which contacts the tissue will beThe impression surface which contacts the tissue will be glossy and the surface which does not come in contact withglossy and the surface which does not come in contact with the tissue will be dullthe tissue will be dull • Wax is added on the dull surface and the impression is placedWax is added on the dull surface and the impression is placed back for 5 min in the mouth .back for 5 min in the mouth . • Procedure is repeated till the impression is completed.Procedure is repeated till the impression is completed. The finished impression must be handled carefully, and theThe finished impression must be handled carefully, and the new cast poured as soon as possible because the wax is fragilenew cast poured as soon as possible because the wax is fragile and subject to distortion.and subject to distortion. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 46. • The fluid wax impression is made with the open mouthThe fluid wax impression is made with the open mouth technique so that there is less danger of over-displacement oftechnique so that there is less danger of over-displacement of ridge tissue by occlusal or vertical forces.ridge tissue by occlusal or vertical forces. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 47. DisadvantagesDisadvantages • The procedure is time consuming.The procedure is time consuming. • If the time periods are not followed accurately, thanIf the time periods are not followed accurately, than impression with excessive tissue displacement will result.impression with excessive tissue displacement will result. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 48. Selected pressure impression techniqueSelected pressure impression technique TheThe objectivesobjectives of the technique are:-of the technique are:- 1.1. the equalization of support between the abutment teeth and thethe equalization of support between the abutment teeth and the soft tissuesoft tissue 2.2. To direct more force to those portions of the ridge which isTo direct more force to those portions of the ridge which is able to absorb the stress without adverse response.able to absorb the stress without adverse response. 3.3. Protect the areas of the ridge which is least able to absorbProtect the areas of the ridge which is least able to absorb force.force. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 50. Areas where relief is provided will be least displacedAreas where relief is provided will be least displaced as the impression is recorded . In those areas of the tray whereas the impression is recorded . In those areas of the tray where relief is not provided greater displacement of the underlyingrelief is not provided greater displacement of the underlying mucosa will occurmucosa will occur Mandibular Arch Posterior regionMandibular Arch Posterior region 1) Crest of Arch1) Crest of Arch 2)Buccal Shelf2)Buccal Shelf 3)Lingual slope – Principally resists horizontal or rotational3)Lingual slope – Principally resists horizontal or rotational forces.forces. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 51. • The end result of this selected pressure impression is that theThe end result of this selected pressure impression is that the denture base made impression will be closely adapted to anddenture base made impression will be closely adapted to and in firm contact with the tissue covering the buccal shelf area ofin firm contact with the tissue covering the buccal shelf area of the edentulous ridge.the edentulous ridge. • The ridge crest on the other hand is lightly adapted to theThe ridge crest on the other hand is lightly adapted to the tissue and the effects of occlusal loading will be less in thistissue and the effects of occlusal loading will be less in this area.area. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 52. Techniques for pouring the corrected castTechniques for pouring the corrected cast impressionimpression www.indiandentalacademy.comwww.indiandentalacademy.com
  • 53. Procedure 1.1. Impression is received in the laboratory. Remove excess impression material from the framework in areas that contact the teeth. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 54. 2. Trim the master cast so that the functional impression can be poured in correct relationship to the remaining teeth. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 55. 3. Seat the framework on the cast, and inspect it for contact between the functional impression and the cast. If contact is present, the cast must be trimmed until clearance is present. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 56. 4. Cut retention grooves into the areas of the cast that will be corrected when the functional impression is poured www.indiandentalacademy.comwww.indiandentalacademy.com
  • 57. 5. Adapt and seal beading wax 2 to 3 mm above the borders of the functional impression www.indiandentalacademy.comwww.indiandentalacademy.com
  • 58. 6. Seat the framework on the cast, and secure it in position with sticky wax www.indiandentalacademy.comwww.indiandentalacademy.com
  • 59. 7.7. Seal the leading edge of the impression to the cast to prevent dental stone from flowing onto the teeth when the cast is poured. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 60. 8. Use strips of base plate wax to complete the boxing of the impression on the buccal and lingual aspects www.indiandentalacademy.comwww.indiandentalacademy.com
  • 61. 9. A tight seal of beading and boxing wax is critical in this pouring method and is difficult to attain. Test the completeness of the seal by pouring clear slurry water into the boxed impression. A difficult area to seal is the relief area under the major connector. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 62. 10. Place the cast and impression in clear slurry water to soak for 4 to 5 minutes in preparation for pouring the corrected cast. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 63. 11. Measure and mix the improved dental stone. Pour the boxed impression by adding small increments of stone and using light vibration. Sufficient stone must be used to support the heel of the cast. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 64. 12. Remove the boxing and luting materials from the corrected cast. Shape the cast on a model trimmer. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 65. 13. Soften the impression material in warm water, and remove13. Soften the impression material in warm water, and remove the framework and impression tray from the corrected cast.the framework and impression tray from the corrected cast. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 66. 14. Burn the impression tray off the framework and place it on the cast. Smooth the land area of the cast, and the corrected cast procedures is complete. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 67. Altered cast techniqueAltered cast technique • Master cast must beMaster cast must be modified in preparation formodified in preparation for altered cast procedure.altered cast procedure. Broken line indicatesBroken line indicates proposed cast modificationsproposed cast modifications for bilateral altered castfor bilateral altered cast procedureprocedure www.indiandentalacademy.comwww.indiandentalacademy.com
  • 68. • Master cast afterMaster cast after modification, Dovetailsmodification, Dovetails have been prepared tohave been prepared to permit mechanicalpermit mechanical interlocking of castinterlocking of cast segmentssegments www.indiandentalacademy.comwww.indiandentalacademy.com
  • 69. • Framework seated onFramework seated on modified master cast andmodified master cast and affixed using modellingaffixed using modelling plastic to minimizeplastic to minimize displacement and distortiondisplacement and distortion Assembly is inverted inAssembly is inverted in preparation for rimming andpreparation for rimming and boxing proceduresboxing procedures www.indiandentalacademy.comwww.indiandentalacademy.com
  • 70. • Utility wax is used to rimUtility wax is used to rim the impression.it is locatedthe impression.it is located 2-3 mm from impression2-3 mm from impression and 3-4mm peripherally.and 3-4mm peripherally. Boxing wax added to form aBoxing wax added to form a watertight vertical wall .watertight vertical wall . Freshly mixed dental stoneFreshly mixed dental stone is then introducedis then introduced www.indiandentalacademy.comwww.indiandentalacademy.com
  • 71. • After the stone has gainedAfter the stone has gained sufficient strength ,thesufficient strength ,the corrected cast is recoveredcorrected cast is recovered and trimmedand trimmed www.indiandentalacademy.comwww.indiandentalacademy.com
  • 72. Review of literatureReview of literature www.indiandentalacademy.comwww.indiandentalacademy.com
  • 73. The altered cast impression technique revisitedThe altered cast impression technique revisited JADA, vol. 130, october 1999; 14;77JADA, vol. 130, october 1999; 14;77 Preoperative figure displaying knife-edge residual ridge with moderate-to-severe resorption. final impression made in a border molded acrylic resin tray that has been attached to the latticework of the cast framework. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 74. Complete seating of the framework on the cast is essential before it is fixed in place with sticky wax. Note the placement of saw cuts and retention slots Before being poured, the final impression is beaded and boxed in the usual manner www.indiandentalacademy.comwww.indiandentalacademy.com
  • 75. The final working altered cast. Occlusal view of a well-fitting, properly adapted removable partial denture. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 76. Although there is some clinical evidence that the alteredAlthough there is some clinical evidence that the altered cast impression procedure decreases the load on thecast impression procedure decreases the load on the abutments. The altered cast impression procedure does notabutments. The altered cast impression procedure does not offer significant advantages over the one piece castoffer significant advantages over the one piece cast www.indiandentalacademy.comwww.indiandentalacademy.com
  • 77. SINGLE- TRAY DUAL- IMPRESSION TECHNIQUE FORSINGLE- TRAY DUAL- IMPRESSION TECHNIQUE FOR DISTAL EXTENSION PARTIAL DENTURESDISTAL EXTENSION PARTIAL DENTURES JOSEPH A. R- JPD 1970(24,1,41-46)JOSEPH A. R- JPD 1970(24,1,41-46) • This technique is basedThis technique is based philosophically onphilosophically on Hindel’s loadHindel’s load distribution principledistribution principle • Records the ridgesRecords the ridges dynamically anddynamically and remaining teethremaining teeth staticallystatically • This techniqueThis technique produces less bulkyproduces less bulky final impressionfinal impression www.indiandentalacademy.comwww.indiandentalacademy.com
  • 78. conclusionconclusion ““ Good technique pays off ” is not merely a motto to hang on a wall but these are words of wisdom. Good technique will indeed result in better treatment and improved patient care. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 79. BIBLIOGRAPHYBIBLIOGRAPHY 1. Glossary of Prosthodontic Terms -8 th Edn, 2005.1. Glossary of Prosthodontic Terms -8 th Edn, 2005. 2. Stewart, Rudd, Kuebker : Clinical Removable Partial2. Stewart, Rudd, Kuebker : Clinical Removable Partial Prosthodontics.Prosthodontics. 3. Kenneth D Rudd, Morrow: Dental Lab, Procedure for3. Kenneth D Rudd, Morrow: Dental Lab, Procedure for Removable Partial Dentures.Removable Partial Dentures. 4. McCracken’s : Removable Partial Prosthodontics -4. McCracken’s : Removable Partial Prosthodontics - 11 edition11 edition www.indiandentalacademy.comwww.indiandentalacademy.com
  • 80. 5. J c davenport ; A colour atlas of removable partial dentures.5. J c davenport ; A colour atlas of removable partial dentures. 6. James s brudwik : Advanced removable partial denture6. James s brudwik : Advanced removable partial denture 7. John Osborne : partial dentures, iv edition7. John Osborne : partial dentures, iv edition www.indiandentalacademy.comwww.indiandentalacademy.com
  • 81. 8. The altered cast impression technique revisited JADA, vol. 130, october 1999; 14;77 9. An altered cast procedure to improve tissue support for removable partial dentures jpd 1994(15), 4, 672- 678 10.single- tray dual- impression technique for distal extension partial dentures. Journal of prosthet dent 1970(24,1,41-46) 11. Selective pressure single impression technique for removable partial denture Journal of prosthet dent 1998 ; 80; 2; 259 www.indiandentalacademy.comwww.indiandentalacademy.com