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Impression materials /certified fixed orthodontic courses by Indian dental academy

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  • Impression Materialswww.indiandentalacademy.com

    www.indiandentalacademy.com*

  • www.indiandentalacademy.comINDIAN DENTAL ACADEMYLeader in continuing dental educationwww.indiandentalacademy.com

    www.indiandentalacademy.com

  • Impression MaterialsNon-elasticElasticAqueous HydrocolloidsNon-aqueous ElastomersCondensationAdditionAgar (reversible)Alginate (irreversible)OBrien Dental Materials & their Selection 1997www.indiandentalacademy.com

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  • OBrien Dental Materials & their Selection 1997www.indiandentalacademy.com

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  • Impression MaterialsNon-elasticElasticAqueous hydrocolloidsAgarAlginateNon-aqueous elastomersPolysulfideSiliconesCondensationAdditionPolyether

    www.indiandentalacademy.com

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  • IndicationsDiagnostic castspreliminaryopposing Indirect reconstructionfixedremovableBite registration

    Giordano Gen Dent 2000www.indiandentalacademy.com

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  • Elastomeric Impression MaterialsViscoelasticphysical properties varyrate of loadingRapidly removedecreases permanent deformationchains recoil from a recoverable distanceincreases tear strength

    Phillips Science of Dental Materials 1996www.indiandentalacademy.com

    www.indiandentalacademy.com*

  • Aqueous HydrocolloidsColloidal suspensionschains align to form fibrilstraps water in intersticesTwo formssolviscous liquidgelelastic solidPlaced intra-orally as solconverts to gelthermal or chemical process

    Phillips Science of Dental Materials 1996www.indiandentalacademy.com

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  • Aqueous HydrocolloidsSemi-permeable membranespoor dimensional stabilityEvaporationSyneresisfibril cross linking continuescontracts with timeexudes waterImbibitionwater absorptionswells

    Phillips Science of Dental Materials 1996www.indiandentalacademy.com

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  • Reversible Hydrocolloid (Agar)Indicationscrown and bridgehigh accuracyExampleSlate Hydrocolloid (Van R)

    www.indiandentalacademy.com

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  • CompositionAgarcomplex polysaccharideseaweedgelling agentBoraxstrength

    Potassium sulfateimproves gypsum surfaceWater (85%)

    OBrien Dental Materials & their Selection 1997www.indiandentalacademy.com

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  • ManipulationGel in tubessyringe and tray material

    www.indiandentalacademy.com

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  • Manipulation3 chamber conditioning unit(1) liquefy at 100C for 10 minutesconverts gel to sol(2) store at 65Cplace in tray(3) temper at 46C for 3 minutesseat traycool with water at 13C for 3 minutesconverts sol to gel

    OBrien Dental Materials & their Selection 1997www.indiandentalacademy.com

    www.indiandentalacademy.com*

  • AdvantagesDimensionally accurateHydrophilicdisplace moisture, blood, fluidsInexpensiveafter initial equipmentNo custom tray or adhesivesPleasantNo mixing required

    Phillips Science of Dental Materials 1996www.indiandentalacademy.com

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  • DisadvantagesInitial expensespecial equipmentMaterial prepared in advancedTears easilyDimensionally unstableimmediate poursingle castDifficult to disinfect

    Phillips Science of Dental Materials 1996www.indiandentalacademy.com

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  • Irreversible Hydrocolloid (Alginate)Most widely used impression material Indicationsstudy modelsremovable fixed partial denturesframeworkExamplesJeltrate (Dentsply/Caulk)Coe Alginate (GC America)

    Phillips Science of Dental Materials 1996www.indiandentalacademy.com

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  • CompositionSodium alginatesalt of alginic acidmucous extraction of seaweed (algae)Calcium sulfatereactor

    Sodium phosphateretarderFillerPotassium fluorideimproves gypsum surface

    OBrien Dental Materials & their Selection 1997www.indiandentalacademy.com

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  • ManipulationWeigh powderPowder added to waterrubber bowlvacuum mixerMixed for 45 sec to 1 minPlace trayRemove 2 to 3 minutes after gelation (loss of tackiness)

    Caswell JADA 1986www.indiandentalacademy.com

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  • AdvantagesInexpensiveEasy to useHydrophilicdisplace moisture, blood, fluidsStock trays

    Phillips Science of Dental Materials 1996www.indiandentalacademy.com

    www.indiandentalacademy.com*

  • DisadvantagesTears easilyDimensionally unstableimmediate pour single castLower detail reproductionunacceptable for fixed prosHigh permanent deformationDifficult to disinfect

    Phillips Science of Dental Materials 1996www.indiandentalacademy.com

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  • Non-Aqueous ElastomersSynthetic rubbersmimic natural rubberscarce during World War IILarge polymerssome chain lengtheningprimarily cross-linking Viscosity classeslow, medium, high, puttymonophasic

    Phillips Science of Dental Materials 1996www.indiandentalacademy.com

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  • OBrien Dental Materials & their Selection 1997www.indiandentalacademy.com

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  • PolysulfideFirst dental elastomersIndicationscomplete dentureremovable fixed partial denturetissuecrown and bridgeExamplesPermlastic (Kerr)Omni-Flex (GC America)

    www.indiandentalacademy.com

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  • CompositionBasepolysulfide polymersfillersplasticizersCatalystlead dioxide (or copper)fillersBy-productwater

    Phillips Science of Dental Materials 1996www.indiandentalacademy.com

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  • --SH HS---------------------SHHS-- S H

    O = Pb = OHS

    -S-S---------------S-S- S S

    + 3PbO + H2OPolysulfide ReactionOBrien Dental Materials & their Selection 1997www.indiandentalacademy.com

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  • ManipulationAdhesive to trayUniform layer custom trayEqual lengths of pastesMix thoroughlywithin one minuteSetting time 8 12 minutesPour within 1 hour

    www.indiandentalacademy.com

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  • AdvantagesLower costcompared to silicones and polyethersLong working timeHigh tear strengthHigh flexibilityGood detail reproduction

    Phillips Science of Dental Materials 1996www.indiandentalacademy.com

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  • DisadvantagesPoor dimensional stabilitywater by-productpour within one hoursingle pourCustom traysMessypaste-paste mixbad odormay stain clothingLong setting time

    Phillips Science of Dental Materials 1996www.indiandentalacademy.com

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  • Condensation SiliconeIndicationscomplete denturescrown and bridgeExamplesSpeedex (Coltene/Whaledent)Primasil (TISS Dental)

    www.indiandentalacademy.com

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  • CompositionBasepoly(dimethylsiloxane)tetraethylorthosilicatefillerCatalystmetal organic esterBy-productethyl alcohol

    Phillips 1996Phillips Science of Dental Materials 1996www.indiandentalacademy.com

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  • Condensation Silicone Reactionmetal organic ester ethanolPhillips Science of Dental Materials 1996www.indiandentalacademy.com

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  • ManipulationMix thoroughlypaste - pastepaste - liquidPutty-wash techniquereduces effect of polymerization shrinkagestock trayputty placedthin plastic sheet spacerpreliminary impressionintraoral custom trayinject wash material

    www.indiandentalacademy.com

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  • AdvantagesBetter elastic propertiesClean, pleasantStock trayputty-washGood working and setting time

    Phillips Science of Dental Materials 1996www.indiandentalacademy.com

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  • Disadvantages

    Poor dimensional stabilityhigh shrinkagepolymerizationevaporation of ethanol pour immediatelywithin 30 minutesHydrophobicpoor wettability

    Phillips Science of Dental Materials 1996www.indiandentalacademy.com

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  • Addition SiliconesAKA: Vinyl polysiloxaneIndicationscrown and bridgedenturebite registrationExamplesExtrude (Kerr)Express (3M/ESPE)Aquasil (Dentsply Caulk)Genie (Sultan Chemists)Virtual (Ivoclar Vivadent)

    Click here for DIS evaluations of VPS impression materialswww.indiandentalacademy.com

    www.indiandentalacademy.com*

  • CompositionImprovement over condensation siliconesno by-productFirst pastevinyl poly(dimethylsiloxane)prepolymerSecond pastesiloxane prepolymerCatalystchloroplatinic acid

    Phillips 1996Phillips Science of Dental Materials 1996www.indiandentalacademy.com

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  • Chloroplatinic Acid Catalyst

    Addition Silicone ReactionPhillips Science of Dental Materials 1996www.indiandentalacademy.com

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  • ManipulationAdhesive to tray Double mixcustom trayheavy-bodylight-body to prepPutty-washstock tray

    Craig Adv Dent Res 1988www.indiandentalacademy.com

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  • AdvantagesHighly accurateHigh dimensional stabilitypour up to one weekStock or custom traysMultiple castsEasy to mixPleasant odor

    Phillips Science of Dental Materials 1996www.indiandentalacademy.com

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  • DisadvantagesExpensiveSulfur inhibits set latex glovesferric and Al sulfateretraction solutionPumice teeth beforeimpressingShort working timeLower tear strengthPossible hydrogen gas releasebubbles on diepalladium added to absorb

    Manikos Aust Dent J 1998www.indianden

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