Casting alloys / dentistry website

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  • Casting alloys / dentistry website

    1. 1. DENTAL CASTINGDENTAL CASTING ALLOYS.ALLOYS. INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.comwww.indiandentalacademy.com
    2. 2. • CLASSIFICATION.CLASSIFICATION. • DIFFERENT CONSTITUENTSDIFFERENT CONSTITUENTS &THEIR ROLE&THEIR ROLE • DIFFERENT ALLOY SYSTEMSDIFFERENT ALLOY SYSTEMS THEIRTHEIR ADVANTAGES &ADVANTAGES &www.indiandentalacademy.comwww.indiandentalacademy.com
    3. 3. •ALLOY:-ALLOY:- A MIXTURE OF TWO OR MOREA MIXTURE OF TWO OR MORE METALS OR METALLOIDS THAT AREMETALS OR METALLOIDS THAT ARE MUTUALLY SOLUBLE IN MOLTEN STATE.MUTUALLY SOLUBLE IN MOLTEN STATE. •CASTING:-CASTING:- SOMETHNG THAT HAS BEENSOMETHNG THAT HAS BEEN CAST IN A MOLD; AN OBJECT FORMED BYCAST IN A MOLD; AN OBJECT FORMED BY THE SOLIDIFICATION OF A FLUID THAT HASTHE SOLIDIFICATION OF A FLUID THAT HAS BEEN POURED OR INJECTED INTO MOLD.BEEN POURED OR INJECTED INTO MOLD. • OROR •THE ACT OF FORMING AN OBJECT IN ATHE ACT OF FORMING AN OBJECT IN A MOLD.MOLD. www.indiandentalacademy.comwww.indiandentalacademy.com
    4. 4. Requirements of the alloys:-Requirements of the alloys:- 1.A casting alloy must be able to produce1.A casting alloy must be able to produce surface oxides for chemical bonding withsurface oxides for chemical bonding with dental porcelain.dental porcelain. 2.A casting alloy should be formulated so its2.A casting alloy should be formulated so its coefficient of thermal expansion is slightlycoefficient of thermal expansion is slightly greater than that of the porcelain veneer togreater than that of the porcelain veneer to maintain the metal porcelain attachment.maintain the metal porcelain attachment. www.indiandentalacademy.comwww.indiandentalacademy.com
    5. 5. The alloy must have melting rangeThe alloy must have melting range considerably higher than the fusing range ofconsiderably higher than the fusing range of the dental porcelain fired on to it.the dental porcelain fired on to it. The alloy must not under go distortion at theThe alloy must not under go distortion at the the firing temperatures of the porcelain.the firing temperatures of the porcelain. The first four requirements must be balancedThe first four requirements must be balanced with technicians need for ease of handling.with technicians need for ease of handling. A casting alloy should be biocompatible.A casting alloy should be biocompatible. www.indiandentalacademy.comwww.indiandentalacademy.com
    6. 6. CLASSIFICATION OF THE DENTALCLASSIFICATION OF THE DENTAL CASTING ALLOYSCASTING ALLOYS THEY ARE CLASSIFIED BASED ON :-THEY ARE CLASSIFIED BASED ON :- 1.ALLOY CLASSIFICATION BASED ON1.ALLOY CLASSIFICATION BASED ON FUNCTION.FUNCTION. 2.ALLOY CLASSIFICATION BASED ON COLOR2.ALLOY CLASSIFICATION BASED ON COLOR &COMPOSITION.&COMPOSITION. 3.THE ADA CLASSIFICATION FOR CAST ALLOYS.3.THE ADA CLASSIFICATION FOR CAST ALLOYS. 4.AN ALTERNATIVE CLASSIFICATION SYSTEM4.AN ALTERNATIVE CLASSIFICATION SYSTEM FOR METAL CERAMIC ALLOYS.FOR METAL CERAMIC ALLOYS. www.indiandentalacademy.comwww.indiandentalacademy.com
    7. 7. CLASSIFICATION BASED ONCLASSIFICATION BASED ON FUNCTIONFUNCTION One of the oldest & simplest methods used toOne of the oldest & simplest methods used to categorize casting alloys was devised by thecategorize casting alloys was devised by the NATIONAL BUREAU OF STANDARDS INNATIONAL BUREAU OF STANDARDS IN 19321932.. The gold based crown & bridge metals of thatThe gold based crown & bridge metals of that time were organized according to function intotime were organized according to function into only four categories & describedonly four categories & described type1,2,3,or4alloystype1,2,3,or4alloys Alloys in each classification or type wereAlloys in each classification or type were arranged based on their gold &platinum grouparranged based on their gold &platinum groupwww.indiandentalacademy.comwww.indiandentalacademy.com
    8. 8. • TYPE –1– SOFT.--- USED FOR THETYPE –1– SOFT.--- USED FOR THE SMALL INLAYSSMALL INLAYS • • TYPE –2– MEDIUM.--- USED FORE THETYPE –2– MEDIUM.--- USED FORE THE THREE QUTER CROWN,THIN BACKINGS.THREE QUTER CROWN,THIN BACKINGS. • TYPE –3– HARD.--- USED FOR THE FULLTYPE –3– HARD.--- USED FOR THE FULL CROWNS, ABUTMENTS & PONTICS.CROWNS, ABUTMENTS & PONTICS. • TYPE –4—EXTRA HARD---DENTURE BASETYPE –4—EXTRA HARD---DENTURE BASE BARS,PARTIAL DENTURE FRAMEBARS,PARTIAL DENTURE FRAME WORK, LONG SPAN FIXED PARTIALWORK, LONG SPAN FIXED PARTIAL www.indiandentalacademy.comwww.indiandentalacademy.com
    9. 9. ALLOY CALSSIFICATION BASEDALLOY CALSSIFICATION BASED ON COLOR &COMPOSITIONON COLOR &COMPOSITION A second method of classification is toA second method of classification is to describe alloys according to their color &describe alloys according to their color & principal element.principal element. 1.YELLOW GOLDS:- yellow color,greater than1.YELLOW GOLDS:- yellow color,greater than 60% of the gold content.60% of the gold content. 2.WHITE GOLDS:-white color but more than2.WHITE GOLDS:-white color but more than 50%of the gold content.50%of the gold content. 3.LOW GOLDS:-usually yellow colored with3.LOW GOLDS:-usually yellow colored with less than 60%of the gold.less than 60%of the gold. www.indiandentalacademy.comwww.indiandentalacademy.com
    10. 10. HIGH PALLADIUM:-white colored ,withHIGH PALLADIUM:-white colored ,with palladium the major component.also containspalladium the major component.also contains small amount of gold &copper,cobalt.small amount of gold &copper,cobalt. SILVER- PALLADIUM:-white coloredSILVER- PALLADIUM:-white colored predominantly silver with substantial amountspredominantly silver with substantial amounts of the palladium to provide nobility &to helpof the palladium to provide nobility &to help control tarnish.control tarnish. PALLADIUM- SILVER :-white colored withPALLADIUM- SILVER :-white colored with palladium the major component ,pluspalladium the major component ,plus substantial component of silver.substantial component of silver.www.indiandentalacademy.comwww.indiandentalacademy.com
    11. 11. ADA CLASSIFICATIONADA CLASSIFICATION In 1984 ADA prepared a new classificationIn 1984 ADA prepared a new classification for cast alloys.for cast alloys. The system was devised for the identificationThe system was devised for the identification in dental procedure codes,where the intrinsicin dental procedure codes,where the intrinsic value of the metals in the castings providedvalue of the metals in the castings provided to patient would influence the amount ofto patient would influence the amount of reimbursement from insurance carriers.reimbursement from insurance carriers. This system of the classification was notThis system of the classification was not intended to indicate usage or performanceintended to indicate usage or performance levels.levels. www.indiandentalacademy.comwww.indiandentalacademy.com
    12. 12. ADA CLASSIFICATIONADA CLASSIFICATION • HIGH NOBLE:CONTAINS 40% GOLD,60%HIGH NOBLE:CONTAINS 40% GOLD,60% OF THE NOBLE METALS.(Au-Ir-Os-Pt-Ru)OF THE NOBLE METALS.(Au-Ir-Os-Pt-Ru) • NOBLE METAL:CONTAINS 25% OF THENOBLE METAL:CONTAINS 25% OF THE NOBLE METAL ELEMENTS.NOBLE METAL ELEMENTS. • PREDOMINANTLY BASEPREDOMINANTLY BASE METAL:CONTAINS LESS THAN 25% OFMETAL:CONTAINS LESS THAN 25% OF THE NOBLE METAL ELEMENTS.THE NOBLE METAL ELEMENTS. www.indiandentalacademy.comwww.indiandentalacademy.com
    13. 13. AN ALTERNATIVEAN ALTERNATIVE CLASSIFICATON SYSTEMCLASSIFICATON SYSTEM With this method the alloys are classifiedWith this method the alloys are classified based on composition & level of thebased on composition & level of the constituent of the major content.constituent of the major content. The alloys are first divided into two groups,The alloys are first divided into two groups, 1.Noble metal1.Noble metal 2.Non noble metals.2.Non noble metals. Each system further divided into constituentEach system further divided into constituent groups.groups. www.indiandentalacademy.comwww.indiandentalacademy.com
    14. 14. ADA CLASSIFICATIONADA CLASSIFICATION • In 1984 ADA given classification of alloysIn 1984 ADA given classification of alloys that are used for the metal ceramicthat are used for the metal ceramic restorations.restorations. • They are classified as,They are classified as, • High noble.High noble. • Noble.Noble. • Predominantly base metal.Predominantly base metal. www.indiandentalacademy.comwww.indiandentalacademy.com
    15. 15. HIGH NOBLE METALHIGH NOBLE METAL ALLOYS.ALLOYS. www.indiandentalacademy.comwww.indiandentalacademy.com
    16. 16. HIGH NOBLE ALLOYHIGH NOBLE ALLOY SYSTEMS.SYSTEMS. • Au-Pt-Pd.Au-Pt-Pd. • Au-Pd-Ag.Au-Pd-Ag. • Au-Pd.Au-Pd. www.indiandentalacademy.comwww.indiandentalacademy.com
    17. 17. DIFFERENT ALLOYDIFFERENT ALLOY SYSTEMS THEIRSYSTEMS THEIR ADVANTAGESADVANTAGES &DISADVANTAGES&DISADVANTAGES www.indiandentalacademy.comwww.indiandentalacademy.com
    18. 18. Au-Pt-PdAu-Pt-Pd www.indiandentalacademy.comwww.indiandentalacademy.com
    19. 19. COMPOSITION:-COMPOSITION:- Gold:75%-88%Gold:75%-88% Platinum:-8%Platinum:-8% Palladium:-11%Palladium:-11% Silver:-5%Silver:-5% Trace elements of indium,iron,&tin areTrace elements of indium,iron,&tin are used for the porcelain bonding.used for the porcelain bonding. www.indiandentalacademy.comwww.indiandentalacademy.com
    20. 20. PALLADIUM:- •Palladium added to increase the corrosion, strength,hardness,tarnish resistance of the gold based alloys. •It increases the melting temperature. •Improves the sag resistance. •PLATINUM:-It increases the strength,hardness,of the gold based alloys. •It improves the corrosion,tarnish &sag resistance. •It improves the density of the gold non gold based alloys. www.indiandentalacademy.comwww.indiandentalacademy.com
    21. 21. •SILVER:- •It lowers the melting range,improves the fluidity,&helps to control the CTE. •It has high affinity for the oxygen, which can lead to the porosity&gassing of the casting. •It is not universally regarded as noble in the oral cavity. www.indiandentalacademy.comwww.indiandentalacademy.com
    22. 22. Au-Pt-PdAu-Pt-Pd • ADVANTAGESADVANTAGES • EXCELLENTEXCELLENT CASTABILITY&PORCCASTABILITY&PORC ELAIN BONDINGELAIN BONDING • EASY TO ADJUSTEASY TO ADJUST &FINISH&FINISH • TARNISH&CORROSITARNISH&CORROSI ON RESISTANCEON RESISTANCE • BIOCOMPATIBLEBIOCOMPATIBLE • NOT TECHNIQUENOT TECHNIQUE SENSITIVESENSITIVE • DISADVANTAGESDISADVANTAGES • Poor sagPoor sag resistanceresistance • Low hardnessLow hardness • Low densityLow density • High costHigh cost www.indiandentalacademy.comwww.indiandentalacademy.com
    23. 23. •GOLD:-it provides the high levels of the tarnish &corrosion. •It increases melting range. •It improves the wettability,burnishability &increases the density. www.indiandentalacademy.comwww.indiandentalacademy.com
    24. 24. Au-Pd-AgAu-Pd-Ag Composition:-Composition:- Gold:39%-53%Gold:39%-53% Palladium:25%-35%Palladium:25%-35% Silver:12%-22%Silver:12%-22% www.indiandentalacademy.comwww.indiandentalacademy.com
    25. 25. • AdvantagesAdvantages • Less expensiveLess expensive • Improved rigidity&sagImproved rigidity&sag resistanceresistance • High nobility levelHigh nobility level • DisadvantagesDisadvantages • Silver content createsSilver content creates potential for porcelainpotential for porcelain discoloration.discoloration. • High costHigh cost • High CTEHigh CTE • Tarnish &corrosionTarnish &corrosion resistanceresistance www.indiandentalacademy.comwww.indiandentalacademy.com
    26. 26. GOLD-PALLADIUM ALLOY SYSTEMSGOLD-PALLADIUM ALLOY SYSTEMS Gold:44%-55%Gold:44%-55% Palladium:35%-45%Palladium:35%-45% Gallium:5%Gallium:5% Indium & tin:8%-12%Indium & tin:8%-12% www.indiandentalacademy.comwww.indiandentalacademy.com
    27. 27. • Excellent castabilityExcellent castability • Good bond strengthGood bond strength • Corrosion & tarnishCorrosion & tarnish • Improved hardness &Improved hardness & strengthstrength • Low density.Low density. • DisadvantagesDisadvantages • Not thermallyNot thermally compatible withcompatible with expansionexpansion • High costHigh cost AdvantagesAdvantages www.indiandentalacademy.comwww.indiandentalacademy.com
    28. 28. NOBLE ALLOY SYSTEMSNOBLE ALLOY SYSTEMS www.indiandentalacademy.comwww.indiandentalacademy.com
    29. 29. • Pd-Au.Pd-Au. • Pd-Au-Ag.Pd-Au-Ag. • Pd-Ag.Pd-Ag. • Pd-Cu.Pd-Cu. • Pd-Co.Pd-Co. • Pd-Ga-AgPd-Ga-Ag www.indiandentalacademy.comwww.indiandentalacademy.com
    30. 30. PALLADIUM – SILVER ALLOY SYSTEMPALLADIUM – SILVER ALLOY SYSTEM Composition:Composition: Palladium:55%-60%Palladium:55%-60% Silver:28%-30%Silver:28%-30% Indium & tin are used.Indium & tin are used. www.indiandentalacademy.comwww.indiandentalacademy.com
    31. 31. • PALLADIUM:-- palladium is added toPALLADIUM:-- palladium is added to increase the strength, hardness,increase the strength, hardness, corrosion&tarnish resistance.corrosion&tarnish resistance. • It elevates the alloy’s melting temperature.It elevates the alloy’s melting temperature. • It improves the sag resistance.It improves the sag resistance. • Palladium possess the a high affinity for thePalladium possess the a high affinity for the hydrogen,oxygen& carbon.hydrogen,oxygen& carbon. • It lowers the density of the gold basedIt lowers the density of the gold based alloys.alloys. www.indiandentalacademy.comwww.indiandentalacademy.com
    32. 32. • TIN:-TIN:- • Tin is the hardening agent that acts as aTin is the hardening agent that acts as a lower melting range of the of an alloy.lower melting range of the of an alloy. • It also assists in oxide layer production forIt also assists in oxide layer production for the porcelain bonding in gold based &the porcelain bonding in gold based & palladium based alloys.palladium based alloys. • Tin is the one of the key trace elements forTin is the one of the key trace elements for the oxidation of the palladium silver alloys.the oxidation of the palladium silver alloys. www.indiandentalacademy.comwww.indiandentalacademy.com
    33. 33. • AdvantagesAdvantages • Low cost & densityLow cost & density • Good castability &Good castability & porcelain bondingporcelain bonding • Low hardnessLow hardness • Excellent sag ,tarnishExcellent sag ,tarnish & corrosion& corrosion resistanceresistance • Suitable for long spanSuitable for long span fpd’sfpd’s • DisadvantagesDisadvantages • DiscolorationDiscoloration • Pd-Ag prone toPd-Ag prone to absorb gasesabsorb gases • High CTEHigh CTE • May form internalMay form internal oxides.oxides. • Should not be cast inShould not be cast in carbon cruciblecarbon crucible www.indiandentalacademy.comwww.indiandentalacademy.com
    34. 34. PALLADIUM-COBALTPALLADIUM-COBALT • composition:composition: • palladium78%-88%.palladium78%-88%. • cobalt 4%-10%cobalt 4%-10% • • trace elements oftrace elements of gallium,indium are used.gallium,indium are used. www.indiandentalacademy.comwww.indiandentalacademy.com
    35. 35. • Cobalt is used for alternative of the nickelCobalt is used for alternative of the nickel based alloys, but the cobalt based alloysbased alloys, but the cobalt based alloys are difficult to process.]are difficult to process.] • Cobalt is added to in palladium alloys toCobalt is added to in palladium alloys to increase the CTE,& acts as a strengthener.increase the CTE,& acts as a strengthener. www.indiandentalacademy.comwww.indiandentalacademy.com
    36. 36. • Advantages.Advantages. • Low costLow cost • Good sag resistanceGood sag resistance • GoodGood castability,polishabiliycastability,polishabiliy • Easier to solderEasier to solder • DisadvantagesDisadvantages • Compatible with highCompatible with high expansion porcelains.expansion porcelains. • Produce aProduce a thick,dark.oxide coloredthick,dark.oxide colored layer may cause bluinglayer may cause bluing of the porcelain.of the porcelain. • More prone to gasMore prone to gas absorption.absorption. www.indiandentalacademy.comwww.indiandentalacademy.com
    37. 37. PALLADIUM-COPPERPALLADIUM-COPPER • palladium 70-80%palladium 70-80% • copper 9-15%copper 9-15% • gold 1-2%gold 1-2% • platinum 1-2%platinum 1-2% www.indiandentalacademy.comwww.indiandentalacademy.com
    38. 38. • COPPER:-COPPER:- • Copper serves as hardening agent.Copper serves as hardening agent. • Lowers the melting range of alloy.Lowers the melting range of alloy. • It helps to form an oxide layer for porcelainIt helps to form an oxide layer for porcelain bonding.bonding. • It lowers the density.It lowers the density. www.indiandentalacademy.comwww.indiandentalacademy.com
    39. 39. • Advantages.Advantages. • Good castability.Good castability. • Low cost than gold.Low cost than gold. • Good tarnish andGood tarnish and corrosion resistant.corrosion resistant. • Compatible withCompatible with dental porcelains.dental porcelains. • Produce dark,thick oxideProduce dark,thick oxide layer.layer. • May discolor someMay discolor some porcelains.porcelains. • Should not be cast in theShould not be cast in the carbon crucibles.carbon crucibles. • Absorbs gases.Absorbs gases. • Suitable for the long spanSuitable for the long span bridges.bridges. • Difficult to polish.Difficult to polish. • High hardnessHigh hardness www.indiandentalacademy.comwww.indiandentalacademy.com
    40. 40. Pg-Ag-AuPg-Ag-Au • composition:composition: • palladium 75-86%palladium 75-86% • silver 1-7%silver 1-7% • gold less than 1%gold less than 1% • Trace amounts of indium & gallium areTrace amounts of indium & gallium are found.found. www.indiandentalacademy.comwww.indiandentalacademy.com
    41. 41. • AdvantagesAdvantages • Low costLow cost • Low densityLow density • Improved sagImproved sag resistance.resistance. • Light colored oxideLight colored oxide layer.layer. • Relatively new alloyRelatively new alloy group no data ongroup no data on long termlong term performances.performances. • Prone to gaseousProne to gaseous absorption.absorption. • Should not be castShould not be cast in carbon crucibles.in carbon crucibles. www.indiandentalacademy.comwww.indiandentalacademy.com
    42. 42. • INDIUM:-INDIUM:- • Lowers the melting range of the alloy.Lowers the melting range of the alloy. • It improves the fluidity.It improves the fluidity. • It has strengthening effect.It has strengthening effect. • It is added to non gold based alloys to formIt is added to non gold based alloys to form an oxide layer.an oxide layer. • It enhances the tarnish & corrosiveIt enhances the tarnish & corrosive resistance.resistance. www.indiandentalacademy.comwww.indiandentalacademy.com
    43. 43. • GALLIUM:GALLIUM: • It is added to the silver free porcelains toIt is added to the silver free porcelains to compensate for the decreased CTEcompensate for the decreased CTE created by silver removal.created by silver removal. www.indiandentalacademy.comwww.indiandentalacademy.com
    44. 44. PREDOMINANTLY BASEPREDOMINANTLY BASE METAL ALLOYSMETAL ALLOYS www.indiandentalacademy.comwww.indiandentalacademy.com
    45. 45. • Ni-Cr-Mo-BeNi-Cr-Mo-Be • Ni-Cr-MoNi-Cr-Mo • Co-Cr-MoCo-Cr-Mo www.indiandentalacademy.comwww.indiandentalacademy.com
    46. 46. NICKEL-CHROMIUM-MOLYBDENUM-NICKEL-CHROMIUM-MOLYBDENUM- BERYLLIUM ALLOYSBERYLLIUM ALLOYS COMPOSITION:COMPOSITION: Nickel:62%-82%Nickel:62%-82% Chromium:11-20%Chromium:11-20% Beryllium:2%Beryllium:2% www.indiandentalacademy.comwww.indiandentalacademy.com
    47. 47. •NICKEL:-it is base for the porcelain alloys. •Its CTE similar to the gold •It provides resistance to corrosion. Lowers the melting temperature of the nickel based alloys. It improves the castability,improves polish ability. Helps to control the oxide layer formation BERYLLIUM:- www.indiandentalacademy.comwww.indiandentalacademy.com
    48. 48. • Aluminum:-lowers the melting range of theAluminum:-lowers the melting range of the nickel based alloys.nickel based alloys. • It acts as a hardening agent.It acts as a hardening agent. • It influences the oxide layer formation.It influences the oxide layer formation. • With cobalt chromium alloys used for theWith cobalt chromium alloys used for the metal ceramic restoration, aluminum is themetal ceramic restoration, aluminum is the on of the element that is etched from theon of the element that is etched from the alloy surface to create micro mechanicalalloy surface to create micro mechanical retention for resin bonded retainers.retention for resin bonded retainers. www.indiandentalacademy.comwww.indiandentalacademy.com
    49. 49. • IRON:-IRON:- • Iron is added to some gold based porcelainIron is added to some gold based porcelain for hardening & oxide production.for hardening & oxide production. SILICON:- •Silicon primarily as an oxide scavenger. •It also act as a hardening agent. www.indiandentalacademy.comwww.indiandentalacademy.com
    50. 50. • AdvantagesAdvantages • Low costLow cost • Low densityLow density • High resistanceHigh resistance • It can produce thinIt can produce thin castingscastings • Poor thermal conductorPoor thermal conductor • Can be etched.Can be etched. • DisadvantagesDisadvantages • Cannot be used with NiCannot be used with Ni sensitive patientssensitive patients • Beryllium may be toxic toBeryllium may be toxic to the technician & patientsthe technician & patients • Bond failure may occurBond failure may occur • High hardnessHigh hardness • Difficult to solderDifficult to solder • Difficult to cut throughDifficult to cut through cemented castingscemented castings www.indiandentalacademy.comwww.indiandentalacademy.com
    51. 51. NICKEL-CHROMIUM ALLOYSNICKEL-CHROMIUM ALLOYS Composition:Composition: Nickel :62%-77%Nickel :62%-77% Chromium :-11%-22%Chromium :-11%-22% www.indiandentalacademy.comwww.indiandentalacademy.com
    52. 52. •Chromium is a solid solution hardening agent that contributes to corrosion resistance. CHROMIUM:- www.indiandentalacademy.comwww.indiandentalacademy.com
    53. 53. BORON:- Boron is a de oxidizer. It reduces the surface tension there by increases the castability. Reduce the ductility & increase the hardness. www.indiandentalacademy.comwww.indiandentalacademy.com
    54. 54. • Do not containDo not contain berylliumberyllium • Low costLow cost • Low density meansLow density means more castings permore castings per ounce.ounce. • DisadvantagesDisadvantages • Cannot be use withCannot be use with nickel sensitivenickel sensitive patientspatients • Produce more oxidesProduce more oxides than Ni-Cr-Be alloys.than Ni-Cr-Be alloys. • May not cast as wellMay not cast as well as Ni-Cr-Be alloysas Ni-Cr-Be alloys www.indiandentalacademy.comwww.indiandentalacademy.com
    55. 55. COBALT – CHROMIUM ALLOYSCOBALT – CHROMIUM ALLOYS Composition:Composition: Cobalt:53%-68%Cobalt:53%-68% Chromium:25%-34%Chromium:25%-34% Trace elements of molybdenumTrace elements of molybdenum ruthenium are added.ruthenium are added. www.indiandentalacademy.comwww.indiandentalacademy.com
    56. 56. CHROMIUM:-CHROMIUM:- • Chromium is a solid solution hardening agentChromium is a solid solution hardening agent that contributes to corrosion resistance.that contributes to corrosion resistance. • COBALT:-used as alternative to the nickelCOBALT:-used as alternative to the nickel based alloys.based alloys. • Cobalt included in the high palladium alloysCobalt included in the high palladium alloys to increase the CTE.to increase the CTE. • It also acts a strengthener.It also acts a strengthener. www.indiandentalacademy.comwww.indiandentalacademy.com
    57. 57. • Molybdenum improves corrosionMolybdenum improves corrosion resistance,influences the oxide layer,helpfulresistance,influences the oxide layer,helpful in adjusting CTE in nickel based alloys.in adjusting CTE in nickel based alloys. www.indiandentalacademy.comwww.indiandentalacademy.com
    58. 58. • RUTHENIUM:RUTHENIUM: • It acts as a grain refiner.It acts as a grain refiner. • It improves the tarnish resistance.It improves the tarnish resistance. www.indiandentalacademy.comwww.indiandentalacademy.com
    59. 59. • ADVANTAGESADVANTAGES • DO NOT CONTAINDO NOT CONTAIN NICKELNICKEL • DO NOT CONTAINDO NOT CONTAIN BERYLLIUMBERYLLIUM • POOR THERMALPOOR THERMAL CONDUCTORSCONDUCTORS • LOW DENSITYLOW DENSITY • LOW COSTLOW COST • DISADVANTAGESDISADVANTAGES • MORE DIFFICULT TOMORE DIFFICULT TO PROCESS THAN NIPROCESS THAN NI BASE ALLOYSBASE ALLOYS • HIGH HARDNESSHIGH HARDNESS • OXIDE MORE THANOXIDE MORE THAN BOTH NI BASEDBOTH NI BASED ALLOYSALLOYS • NO INFORMATIONNO INFORMATION ON LONG TERMON LONG TERM CLINICAL STUDIES.CLINICAL STUDIES. www.indiandentalacademy.comwww.indiandentalacademy.com
    60. 60. SOLDERING.SOLDERING. www.indiandentalacademy.comwww.indiandentalacademy.com
    61. 61. • SOLDERING:-A group of process that joinSOLDERING:-A group of process that join metal by heating them to a suitablemetal by heating them to a suitable temperature below the solidus of thetemperature below the solidus of the substrate metals & applying a filler metalsubstrate metals & applying a filler metal having liquidus not exceeding 450 degreehaving liquidus not exceeding 450 degree centigrade that melts and flows by capillarycentigrade that melts and flows by capillary attraction between the parts with outattraction between the parts with out appreciably affecting the dimension of joinedappreciably affecting the dimension of joined structure.structure. • In dentistry,many metals are joined byIn dentistry,many metals are joined by brazing,although,the term soldering is used.brazing,although,the term soldering is used.www.indiandentalacademy.comwww.indiandentalacademy.com
    62. 62. • BRAZING:The process of joining metalsBRAZING:The process of joining metals above 450 degree centigrade.above 450 degree centigrade. • WELDING:-The joining of two or more metalWELDING:-The joining of two or more metal pieces by applying heat, pressure,or bothpieces by applying heat, pressure,or both with or without filler material, to producewith or without filler material, to produce localized union across the interface throughlocalized union across the interface through fusion or diffusion.fusion or diffusion. • SOLDERING FLUX: A material used toSOLDERING FLUX: A material used to prevent the formation of,or to dissolve &prevent the formation of,or to dissolve & facilitate removal of,oxides & otherfacilitate removal of,oxides & other undesirable substances that may reduce theundesirable substances that may reduce thewww.indiandentalacademy.comwww.indiandentalacademy.com
    63. 63. SOLDERING OF FIXEDSOLDERING OF FIXED PARTIAL DENTURES.PARTIAL DENTURES. www.indiandentalacademy.comwww.indiandentalacademy.com
    64. 64. PHYSICAL REQUIREMENTS OFPHYSICAL REQUIREMENTS OF SOLDER MATERIALSSOLDER MATERIALS • Resistance to tarnish & corrosion.Resistance to tarnish & corrosion. • Fusion temperature 90-180 degreeFusion temperature 90-180 degree Fahrenheit below the parts to be joined.Fahrenheit below the parts to be joined. • Free flowing when melted.Free flowing when melted. • Resistance to pitting.Resistance to pitting. • At least as strong as the parts to be joined.At least as strong as the parts to be joined. • Color compatible with the parts to be joined.Color compatible with the parts to be joined. www.indiandentalacademy.comwww.indiandentalacademy.com
    65. 65. SOLDERING FLUXESSOLDERING FLUXES • Flux is Latin word means flow.Dental do notFlux is Latin word means flow.Dental do not flow or wet the metallic surfaces that have anflow or wet the metallic surfaces that have an oxide layer.The flux aid in the removal of theoxide layer.The flux aid in the removal of the oxide layer so as to increase the flow of theoxide layer so as to increase the flow of the molten solder.molten solder. • In addition the flux also dissolves theIn addition the flux also dissolves the impurities,prevents the oxidation of theimpurities,prevents the oxidation of the metals.metals. • Fluxes used commonly are:Fluxes used commonly are: • Borax glass– 55%.Borax glass– 55%. • Boric acid --35%Boric acid --35% • Silica-- 10%.Silica-- 10%.www.indiandentalacademy.comwww.indiandentalacademy.com
    66. 66. • ANTI FLUXANTI FLUX • Anti flux is a material that is used to confineAnti flux is a material that is used to confine the flow of the molten solder over the metalsthe flow of the molten solder over the metals being joined.being joined. • The commonly used anti fluxes are pencilThe commonly used anti fluxes are pencil markings, graphite lines, iron rouge.markings, graphite lines, iron rouge. www.indiandentalacademy.comwww.indiandentalacademy.com
    67. 67. Fundamental considerationsFundamental considerations • Position accurately the uncontaminated partsPosition accurately the uncontaminated parts to be joined.to be joined. • Determine the solder gaps and configuration.Determine the solder gaps and configuration. • Place the flux and solder within the jointPlace the flux and solder within the joint space.space. • Heat the parent metal and solder until theHeat the parent metal and solder until the solder flows, filling the joint space.solder flows, filling the joint space. • Remove the heat as soon as possible.Remove the heat as soon as possible. • Inspect the connection and correct fInspect the connection and correct f necessary.necessary. • Gap to be maintained is 0.3mm.Gap to be maintained is 0.3mm.www.indiandentalacademy.comwww.indiandentalacademy.com
    68. 68. • ARMAMENTAIRUMARMAMENTAIRUM • Plaster bowl & spatulaPlaster bowl & spatula • Impression plaster.Impression plaster. • Bite registration paste.Bite registration paste. • Index tray or tongue blade.Index tray or tongue blade. • Petrolatum.Petrolatum. • Laboratory knife with no.25 blade.Laboratory knife with no.25 blade. • PKT waxing instrument no 1& 2.PKT waxing instrument no 1& 2. • Straight hand piece.Straight hand piece. • Soldering investment.Soldering investment. • Vibrator.Vibrator. www.indiandentalacademy.comwww.indiandentalacademy.com
    69. 69. • Fisher burner &Fisher burner & matches.matches. • Tripod screen.Tripod screen. • SolderSolder • Blow pipe.Blow pipe. • Tooth brush.Tooth brush. www.indiandentalacademy.comwww.indiandentalacademy.com
    70. 70. • Remove the provisional restoration from theRemove the provisional restoration from the patient’s mouth make certain that there arepatient’s mouth make certain that there are no temporary cement left on the toothno temporary cement left on the tooth preparation.preparation. • Try in the single retainer first and thenTry in the single retainer first and then retainer pontic combination, verify theretainer pontic combination, verify the marginal fitmarginal fit • Adjust the occlusion, do not polish theAdjust the occlusion, do not polish the casting at this stage.because polishing rougecasting at this stage.because polishing rouge is iron-di- oxide, a specific anti flux for www.indiandentalacademy.comwww.indiandentalacademy.com
    71. 71. • Mix a small amount ofMix a small amount of fast settingfast setting impression plaster &impression plaster & place it on plasticplace it on plastic index tray orindex tray or thoroughly wet tonguethoroughly wet tongue depressor.depressor. www.indiandentalacademy.comwww.indiandentalacademy.com
    72. 72. 1.1. Place the tray inPlace the tray in the mouth overthe mouth over thethe castings.oncecastings.once the plaster set,the plaster set, remove theremove the template andtemplate and check for thecheck for the accuracyaccuracy www.indiandentalacademy.comwww.indiandentalacademy.com
    73. 73. • Trim the excessTrim the excess plaster so that afterplaster so that after seating the template,seating the template, it is possible to coverit is possible to cover their margins withtheir margins with solderingsoldering investment.lute theinvestment.lute the castings with thecastings with the sticky wax.sticky wax. www.indiandentalacademy.comwww.indiandentalacademy.com
    74. 74. www.indiandentalacademy.comwww.indiandentalacademy.com
    75. 75. • A strip of boxing waxA strip of boxing wax 2.5mm thick wide2.5mm thick wide wrapped around thewrapped around the index.index. www.indiandentalacademy.comwww.indiandentalacademy.com
    76. 76. www.indiandentalacademy.comwww.indiandentalacademy.com
    77. 77. • Mix the solderingMix the soldering investment accordinginvestment according to the manufacturerto the manufacturer instructions.completelinstructions.completel y fill the interior of they fill the interior of the retainer castings.retainer castings. Care to avoid buryingCare to avoid burying the prosthesis in thethe prosthesis in the investment.investment. www.indiandentalacademy.comwww.indiandentalacademy.com
    78. 78. • Remove the plasterRemove the plaster template & trim thetemplate & trim the investment so, thatinvestment so, that soldering modelsoldering model allows the readyallows the ready access of heat to theaccess of heat to the joint area.joint area. www.indiandentalacademy.comwww.indiandentalacademy.com
    79. 79. • Heat the solderingHeat the soldering model sufficiently tomodel sufficiently to vaporize waxvaporize wax remaining in the joint.remaining in the joint. www.indiandentalacademy.comwww.indiandentalacademy.com
    80. 80. • While the joint is stillWhile the joint is still warm coat the solderwarm coat the solder with flux and placewith flux and place the solder in thethe solder in the place.place. www.indiandentalacademy.comwww.indiandentalacademy.com
    81. 81. • Reheat the soldering model until the solderReheat the soldering model until the solder flows.flows. • Remove the flame, apply bluish flame inRemove the flame, apply bluish flame in circular manner around the solder model.circular manner around the solder model. • As the solder is about to flow; it slumps andAs the solder is about to flow; it slumps and loses rectangular definition.loses rectangular definition. • Use only reducing portions of the flame,Use only reducing portions of the flame, characterized by shiny areas on the metalcharacterized by shiny areas on the metal directly under the flame.directly under the flame. • Allow the prosthesis for the bench cool toAllow the prosthesis for the bench cool to heat treat the metals properly.heat treat the metals properly. • Try the assembled prosthesis in the mouthTry the assembled prosthesis in the mouth after finishing & polishing.after finishing & polishing.www.indiandentalacademy.comwww.indiandentalacademy.com
    82. 82. POST VENERINGPOST VENERING SOLDERINGSOLDERING www.indiandentalacademy.comwww.indiandentalacademy.com
    83. 83. • Try in the units in the mouth & makeTry in the units in the mouth & make necessary adjustments.necessary adjustments. • Remove the FPD from the mouth,cut theRemove the FPD from the mouth,cut the joint using disk.joint using disk. • A soldering index is made with the quickA soldering index is made with the quick setting plaster.setting plaster. www.indiandentalacademy.comwww.indiandentalacademy.com
    84. 84. • Making the plasterMaking the plaster index.index. www.indiandentalacademy.comwww.indiandentalacademy.com
    85. 85. www.indiandentalacademy.comwww.indiandentalacademy.com
    86. 86. • Cyanoacrylate liquidCyanoacrylate liquid resin is squeezedresin is squeezed onto the joint space.onto the joint space. www.indiandentalacademy.comwww.indiandentalacademy.com
    87. 87. • To preventTo prevent investment forminvestment form contaminating thecontaminating the ceramic place 1.0mmceramic place 1.0mm thick ivory wax overthick ivory wax over gingival one half togingival one half to 2/32/3rdrd of the facialof the facial surfaces of thesurfaces of the retainer and pontic.retainer and pontic. www.indiandentalacademy.comwww.indiandentalacademy.com
    88. 88. • Mix a small amount ofMix a small amount of the solderingthe soldering investment andinvestment and carefully vibrate intocarefully vibrate into the crowns.the crowns. www.indiandentalacademy.comwww.indiandentalacademy.com
    89. 89. • Soldering investmentSoldering investment is placed over the flatis placed over the flat surface.surface. www.indiandentalacademy.comwww.indiandentalacademy.com
    90. 90. • Put the FPD into thePut the FPD into the investment.investment. www.indiandentalacademy.comwww.indiandentalacademy.com
    91. 91. • Investment is pushedInvestment is pushed over the lingualover the lingual surfaces of the FPDsurfaces of the FPD www.indiandentalacademy.comwww.indiandentalacademy.com
    92. 92. • The investment isThe investment is trimmed leavingtrimmed leaving 3.0mm around the3.0mm around the castings. The entirecastings. The entire block is beveled.block is beveled. www.indiandentalacademy.comwww.indiandentalacademy.com
    93. 93. • A V shaped notchA V shaped notch is placed over theis placed over the lingual surface.lingual surface. www.indiandentalacademy.comwww.indiandentalacademy.com
    94. 94. • The wax layerThe wax layer separates theseparates the investment andinvestment and porcelain.porcelain. www.indiandentalacademy.comwww.indiandentalacademy.com
    95. 95. • After the waxAfter the wax removal, a spaceremoval, a space between porcelainbetween porcelain and investmentand investment protects the porcelain.protects the porcelain. www.indiandentalacademy.comwww.indiandentalacademy.com
    96. 96. MECHANISM OFMECHANISM OF PORCELAIN –METALPORCELAIN –METAL ATTACHMENTATTACHMENT • Four theoriesFour theories have been proposedhave been proposed to explain the processes that lead toto explain the processes that lead to porcelain-to-metal bonding:porcelain-to-metal bonding: • 1. Van der waals forces.1. Van der waals forces. • 2. Mechanical retention.2. Mechanical retention. • 3. Compression bonding.3. Compression bonding. • 4. Direct chemical bonding.4. Direct chemical bonding. www.indiandentalacademy.comwww.indiandentalacademy.com
    97. 97. VAN DER WAALS FORCES.VAN DER WAALS FORCES. 1. The attraction between charged atoms that1. The attraction between charged atoms that are in intimate contact yet do not actuallyare in intimate contact yet do not actually exchange electrons is derived from van derexchange electrons is derived from van der waals forces.waals forces. 2. These secondary forces are generated more2. These secondary forces are generated more by a physical attraction between chargedby a physical attraction between charged particles than by an actual sharing or exchangeparticles than by an actual sharing or exchange of electrons in primary(chemical) bonding.of electrons in primary(chemical) bonding. 3. Van der waals forces are generally weak,3. Van der waals forces are generally weak, because nearly all the positive and negativebecause nearly all the positive and negative charges present in these atoms are satisfied incharges present in these atoms are satisfied in a single molecule.a single molecule. www.indiandentalacademy.comwww.indiandentalacademy.com
    98. 98. 4. It is also believed that bonding entails4. It is also believed that bonding entails some measure of true adhesion based onsome measure of true adhesion based on the extent to which the metal substructurethe extent to which the metal substructure is wetted by the softened dental porcelain.is wetted by the softened dental porcelain. 5. The better the wetting of the metal5. The better the wetting of the metal surface, greater the vanderwaal’s forces.surface, greater the vanderwaal’s forces. 6. Furthermore, porcelain’s adhesion to6. Furthermore, porcelain’s adhesion to metal can be diminished or enhanced bymetal can be diminished or enhanced by alterations in the surfacealterations in the surface characters(texture) of the porcelain-characters(texture) of the porcelain- bearing surface on the substructure.bearing surface on the substructure. www.indiandentalacademy.comwww.indiandentalacademy.com
    99. 99. 7. A rough, contaminated metal surface7. A rough, contaminated metal surface will inhibit wetting and reduce thewill inhibit wetting and reduce the vanderwaals bond strength. On the othervanderwaals bond strength. On the other hand, a slightly textured surface, createdhand, a slightly textured surface, created by finishing with uncontaminatedby finishing with uncontaminated aluminum oxide abrasives and followedaluminum oxide abrasives and followed by air abrasion(blasting) with 50 micronsby air abrasion(blasting) with 50 microns aluminium oxide, reportedly will promotealuminium oxide, reportedly will promote wetting by the liquid porcelain.wetting by the liquid porcelain. 8. Improved wetting is then accompanied8. Improved wetting is then accompanied by an increase in adhesion throughby an increase in adhesion through vanderwaals forces.vanderwaals forces. www.indiandentalacademy.comwww.indiandentalacademy.com
    100. 100. MECHANICAL RETENTION:MECHANICAL RETENTION: • 1. The porcelain-bearing area of a metal1. The porcelain-bearing area of a metal casting contains many microscopiccasting contains many microscopic irregularities into which opaque porcelainirregularities into which opaque porcelain may flow when fired.may flow when fired. • 2. Air abrading the metal with aluminum2. Air abrading the metal with aluminum oxide is believed to enhance mechanicaloxide is believed to enhance mechanical retention further by eliminating surfaceretention further by eliminating surface irregularities ( stress concentrations) whileirregularities ( stress concentrations) while increasing the overall surface areaincreasing the overall surface area available for bonding.available for bonding. www.indiandentalacademy.comwww.indiandentalacademy.com
    101. 101. 3. Despite it’s presence, mechanical3. Despite it’s presence, mechanical retention’s contribution to bonding mayretention’s contribution to bonding may be relatively limited.be relatively limited. 4. Dental porcelain does not require a4. Dental porcelain does not require a roughened area to bond to metal. In factroughened area to bond to metal. In fact porcelain will fuse to a well polishedporcelain will fuse to a well polished surface, but some surface roughness issurface, but some surface roughness is effective in increasing bonding forces.effective in increasing bonding forces. www.indiandentalacademy.comwww.indiandentalacademy.com
    102. 102. COMPRESSION BONDINGCOMPRESSION BONDING • Dental porcelain is strongest underDental porcelain is strongest under compression and weakest under tension.compression and weakest under tension. • Hence , if the coefficient of thermalHence , if the coefficient of thermal expansion of the metal substructure isexpansion of the metal substructure is greater than that of the porcelain placedgreater than that of the porcelain placed over it, the porcelain should be placedover it, the porcelain should be placed under compression on cooling.under compression on cooling. • 1. When cooling a restoration with a1. When cooling a restoration with a full-porcelain veneer, the metal contractsfull-porcelain veneer, the metal contracts faster than the porcelain but is resistedfaster than the porcelain but is resisted by the porcelain’s lower coefficient ofby the porcelain’s lower coefficient of thermal expansion.thermal expansion. www.indiandentalacademy.comwww.indiandentalacademy.com
    103. 103. • 2. This difference in contraction rates2. This difference in contraction rates creates tensile forces on the metal andcreates tensile forces on the metal and corresponding compressive forces on thecorresponding compressive forces on the porcelain. Without the wraparound effectporcelain. Without the wraparound effect created in a full porcelain restoration,created in a full porcelain restoration, there is less likelihood this compressionthere is less likelihood this compression bonding will develop fully.bonding will develop fully. www.indiandentalacademy.comwww.indiandentalacademy.com
    104. 104. THERMAL EXPANSIONTHERMAL EXPANSION • Generally substances increase in theGenerally substances increase in the length and volume when they are heated.length and volume when they are heated. This phenomenon is called as thermalThis phenomenon is called as thermal expansion.expansion. • The specific rate of change in length of aThe specific rate of change in length of a particular substance per unit change inparticular substance per unit change in temperature is called coefficient of lineartemperature is called coefficient of linear expansion.expansion. • The rate of change in volume is calledThe rate of change in volume is called coefficient of cubical expansion.coefficient of cubical expansion. • These may generally be called coefficientThese may generally be called coefficient of thermal expansion or simply thermalof thermal expansion or simply thermal expansion.expansion.www.indiandentalacademy.comwww.indiandentalacademy.com
    105. 105. RELATION BETWEEN METALRELATION BETWEEN METAL AND PORCELAINAND PORCELAIN • When porcelain is fused to metal, threeWhen porcelain is fused to metal, three possible relations can exist in thermalpossible relations can exist in thermal expansion:expansion: • 1. Thermal expansion (or contraction)1. Thermal expansion (or contraction) is greater in porcelain than in metal.is greater in porcelain than in metal. • 2. Thermal expansion (or contraction)2. Thermal expansion (or contraction) is equal between metal and porcelain.is equal between metal and porcelain. • 3. Thermal expansion (or contraction)3. Thermal expansion (or contraction) is greater in metal than in porcelain.is greater in metal than in porcelain. www.indiandentalacademy.comwww.indiandentalacademy.com
    106. 106. THERMAL EXPANSION ISTHERMAL EXPANSION IS GREATERGREATER ININ PORCELAIN THANPORCELAIN THAN IN METAL.IN METAL. • Greater thermal expansion in porcelainGreater thermal expansion in porcelain means that during the time after porcelainmeans that during the time after porcelain has lost thermoplastic fluidity in thehas lost thermoplastic fluidity in the course of cooling, but after melting ofcourse of cooling, but after melting of porcelain at high temperature, porcelain isporcelain at high temperature, porcelain is apt to contract to be smaller and shorterapt to contract to be smaller and shorter than metal until it reaches roomthan metal until it reaches room temperature.temperature. • Therefore, assuming that they areTherefore, assuming that they are separated, there will be a difference inseparated, there will be a difference in length between them.length between them.www.indiandentalacademy.comwww.indiandentalacademy.com
    107. 107. • Hence porcelain becomes shorter afterHence porcelain becomes shorter after cooling although they had the samecooling although they had the same length before heating.length before heating. • In the ceramo-metallic system, porcelainIn the ceramo-metallic system, porcelain side is subjected to tensile stress whileside is subjected to tensile stress while the metal side is subjected tothe metal side is subjected to compressive stress as they are fusedcompressive stress as they are fused together. As a result, the porcelain, whichtogether. As a result, the porcelain, which is very weak against tensile stress, willis very weak against tensile stress, will crack immediately.crack immediately. www.indiandentalacademy.comwww.indiandentalacademy.com
    108. 108. THERMAL EXPANSION IS EQUALTHERMAL EXPANSION IS EQUAL BETWEEN METAL ANDBETWEEN METAL AND PORCELAINPORCELAIN • As metal and porcelain expand orAs metal and porcelain expand or contract at the same rate, there will be nocontract at the same rate, there will be no difference in dimensions between them atdifference in dimensions between them at all.all. • As a result, porcelain receives no stressAs a result, porcelain receives no stress from metal and thus cracking does notfrom metal and thus cracking does not occur in the stable porcelain unless undueoccur in the stable porcelain unless undue external force is applied.external force is applied. • It is very difficult, however, to obtain theIt is very difficult, however, to obtain the identical curves for coefficient of thermalidentical curves for coefficient of thermal expansion between porcelain and metal,expansion between porcelain and metal, and under ordinary conditions there is aand under ordinary conditions there is awww.indiandentalacademy.comwww.indiandentalacademy.com
    109. 109. THERMAL EXPANSION ISTHERMAL EXPANSION IS GREATER IN METAL THAN INGREATER IN METAL THAN IN PORCELAIN.PORCELAIN. • In general, this thermal expansionIn general, this thermal expansion relationship exists between metal andrelationship exists between metal and porcelain in the dental metal-ceramicporcelain in the dental metal-ceramic system.system. • The objective of such a relationship is toThe objective of such a relationship is to obtain the most stable assembly afterobtain the most stable assembly after firing.firing. • Fractures do not usually occur sinceFractures do not usually occur since porcelain has very high compressionporcelain has very high compression strength, although the porcelain side isstrength, although the porcelain side is subjected to compressive stress as thesubjected to compressive stress as the metal contracts more than porcelainmetal contracts more than porcelain www.indiandentalacademy.comwww.indiandentalacademy.com
    110. 110. • However, this does not mean thatHowever, this does not mean that cracking will never occur.cracking will never occur. • If there is a significant difference inIf there is a significant difference in thermal expansion between metal andthermal expansion between metal and porcelain, a shearing force acts on theirporcelain, a shearing force acts on their interface, and if stress is sufficiently great,interface, and if stress is sufficiently great, cracking, or fracture may occur.cracking, or fracture may occur. www.indiandentalacademy.comwww.indiandentalacademy.com
    111. 111. CHEMICAL BONDINGCHEMICAL BONDING • The single most significant mechanism ofThe single most significant mechanism of porcelain-metal attachment is a chemicalporcelain-metal attachment is a chemical bond between dental porcelain and thebond between dental porcelain and the oxides on the surface of the metaloxides on the surface of the metal substructure.substructure. • There are those who believe that twoThere are those who believe that two mechanisms might exist within themechanisms might exist within the chemical (or molecular) bonding theory.chemical (or molecular) bonding theory. • According to one hypothesis,the oxideAccording to one hypothesis,the oxide layer is permanently bonded to the metallayer is permanently bonded to the metal substructure on one side while the dentalsubstructure on one side while the dental porcelain remains on the other.porcelain remains on the other.www.indiandentalacademy.comwww.indiandentalacademy.com
    112. 112. • The oxide layer itself is sandwiched inThe oxide layer itself is sandwiched in between the metal substructure and thebetween the metal substructure and the opaque porcelain.opaque porcelain. • This sandwich theory is undesirable inThis sandwich theory is undesirable in that a thick oxide layer might exist thatthat a thick oxide layer might exist that would weaken the attachment of metal towould weaken the attachment of metal to porcelain.porcelain. • The second, and more likely, theoryThe second, and more likely, theory suggests that the surface oxidessuggests that the surface oxides dissolve, or are dissolved by the opaquedissolve, or are dissolved by the opaque porcelain layer.porcelain layer. • The porcelain is then brought into atomicThe porcelain is then brought into atomic contact with the metal surface forcontact with the metal surface for enhanced wetting and direct chemicalenhanced wetting and direct chemical bonding so metal and porcelain sharewww.indiandentalacademy.comwww.indiandentalacademy.com
    113. 113. • From a chemical standpoint, bothFrom a chemical standpoint, both covalent and ionic bonds are thought tocovalent and ionic bonds are thought to form but only a monomolecular( single)form but only a monomolecular( single) layer of oxides is believed to belayer of oxides is believed to be required for chemical bonding to occur.required for chemical bonding to occur. www.indiandentalacademy.comwww.indiandentalacademy.com
    114. 114. PORCELAIN METAL BONDPORCELAIN METAL BOND FAILURESFAILURES • Metal ceramic alloys, whether noble or baseMetal ceramic alloys, whether noble or base metals, all oxidize differently because ofmetals, all oxidize differently because of variations in their composition.variations in their composition. • If the oxidation process is not performedIf the oxidation process is not performed properly,the subsequent porcelain-metalproperly,the subsequent porcelain-metal bond may be weak. The consequences ofbond may be weak. The consequences of bond failure,be the failure immediate orbond failure,be the failure immediate or delayed,obviously costly.delayed,obviously costly. www.indiandentalacademy.comwww.indiandentalacademy.com
    115. 115. PORCELAIN DELAMINATIONPORCELAIN DELAMINATION • With base metal alloys, the separation ofWith base metal alloys, the separation of porcelain veneer from the metal subporcelain veneer from the metal sub structure can be more a loss of thestructure can be more a loss of the attachment of the oxide layer that is eitherattachment of the oxide layer that is either too thick or is poorly adherent to the metaltoo thick or is poorly adherent to the metal sub structure.sub structure. • The porcelain and oxide film retain theirThe porcelain and oxide film retain their bond yet become detached or delaminatedbond yet become detached or delaminated at the porcelain-metal junction.at the porcelain-metal junction. • Over oxidation is the particular problem withOver oxidation is the particular problem with heavily oxidizing base metalsheavily oxidizing base metals www.indiandentalacademy.comwww.indiandentalacademy.com
    116. 116. • In some instance bond failure may not beIn some instance bond failure may not be due to chemical bond failure.in contrarary,itdue to chemical bond failure.in contrarary,it may be due to too thick of the oxide layer ormay be due to too thick of the oxide layer or poor adherence of the oxide layer to thepoor adherence of the oxide layer to the metal structure.metal structure. • Excessive absorption of the oxides byExcessive absorption of the oxides by porcelains can lower the coefficient ofporcelains can lower the coefficient of thermal expansion.thermal expansion. www.indiandentalacademy.comwww.indiandentalacademy.com
    117. 117. INCOMPITENT MATERIALSINCOMPITENT MATERIALS • Bond failure may occur due to physicalBond failure may occur due to physical incompatibility between porcelain and metal.incompatibility between porcelain and metal. • The difference in the coefficient of thermalThe difference in the coefficient of thermal expansion of porcelain and the metal mayexpansion of porcelain and the metal may contribute to the failure of the bonding.contribute to the failure of the bonding. www.indiandentalacademy.comwww.indiandentalacademy.com
    118. 118. OVER OXIDATION/UNDEROVER OXIDATION/UNDER OXIDATIONOXIDATION • The oxidation procedure varies for alloys ofThe oxidation procedure varies for alloys of different compositions.so the process it selfdifferent compositions.so the process it self should not be taken for granted.should not be taken for granted. • No one technique can be used for everyNo one technique can be used for every type of metal ceramic alloy.type of metal ceramic alloy. • Careful processing followed by anCareful processing followed by an assessment of post oxidation appearance ofassessment of post oxidation appearance of each casting will ensure that the procedureeach casting will ensure that the procedure was accomplished correctly.was accomplished correctly. www.indiandentalacademy.comwww.indiandentalacademy.com
    119. 119. • Over oxidation or under oxidation should beOver oxidation or under oxidation should be reprocessed accordingly until uniform oxidereprocessed accordingly until uniform oxide of desired color and thickness recommendedof desired color and thickness recommended for the alloy involved.for the alloy involved. www.indiandentalacademy.comwww.indiandentalacademy.com
    120. 120. CONTAMINATIONCONTAMINATION • That that are demonstrated some form ofThat that are demonstrated some form of contamination may not have to be remade.contamination may not have to be remade. • Simple finishing, a substructure’s porcelainSimple finishing, a substructure’s porcelain bearing area may be all that is necessarybearing area may be all that is necessary when surface de bonding becomeswhen surface de bonding becomes evident.evident. www.indiandentalacademy.comwww.indiandentalacademy.com
    121. 121. POCELAIN APPLICATIONPOCELAIN APPLICATION METHODSMETHODS • INSTRUMENTS AND EQIUPMENTS:INSTRUMENTS AND EQIUPMENTS: • BrushesBrushes • Carving instrumentsCarving instruments • SpatulaSpatula • Razor knifesRazor knifes • HemostatHemostat • Condensation mallet or instrument.Condensation mallet or instrument. • Glass or ceramic mixing slabGlass or ceramic mixing slab www.indiandentalacademy.comwww.indiandentalacademy.com
    122. 122. PORCELAIN FURNACEPORCELAIN FURNACE • Three types of the furnaces are available:Three types of the furnaces are available: • Manual.Manual. • Automatic.Automatic. • Programmable.Programmable. • There certain futures common to all types of theThere certain futures common to all types of the furnaces.furnaces. • For example all low fusing porcelain are fired underFor example all low fusing porcelain are fired under vacuum rather than in atmospheric pressure.so, allvacuum rather than in atmospheric pressure.so, all furnaces are equipped so the firing chamber orfurnaces are equipped so the firing chamber or muffle can be sealed and, with the aid of amuffle can be sealed and, with the aid of a pump,establish & maintain a vacuum during firing.pump,establish & maintain a vacuum during firing. www.indiandentalacademy.comwww.indiandentalacademy.com
    123. 123. • In the event the vacuum does not reach anIn the event the vacuum does not reach an adequate level, or if the firing chamber doesadequate level, or if the firing chamber does not properly seal, resulting in a loss ofnot properly seal, resulting in a loss of vacuum during the firing cycle, the quality ofvacuum during the firing cycle, the quality of the fired porcelain will be compromised.the fired porcelain will be compromised. • There will be significant loss of theThere will be significant loss of the translucency,translucency, And vitality in the fired porcelain.And vitality in the fired porcelain. A porcelain furnace should have an adjustableA porcelain furnace should have an adjustable rate of climb from the low entry temperaturerate of climb from the low entry temperature up to high firing temperature.up to high firing temperature. www.indiandentalacademy.comwww.indiandentalacademy.com
    124. 124. • Most furnaces can also be set to hold the work at aMost furnaces can also be set to hold the work at a temperature for a a specified length of time astemperature for a a specified length of time as determined by case by case.determined by case by case. • There two basic categories depending on theThere two basic categories depending on the manner of entry into the muffle.manner of entry into the muffle. • Form front to backForm front to back • Front loading furnaces.Front loading furnaces. • The front loading furnaces hotter near back of theThe front loading furnaces hotter near back of the muffle and cooler near door.muffle and cooler near door. • Those sub structures oxidized in the rear mostThose sub structures oxidized in the rear most portion of the muffle will have a significantly heavierportion of the muffle will have a significantly heavier oxide layeroxide layer www.indiandentalacademy.comwww.indiandentalacademy.com
    125. 125. • Furnaces in the second category have aFurnaces in the second category have a vertical entry in to the muffle. With thevertical entry in to the muffle. With the vertical loading design,the muffle flat formvertical loading design,the muffle flat form with the restoration in the center is raised upwith the restoration in the center is raised up to furnace muffle.to furnace muffle. • The vertical loading design reportedlyThe vertical loading design reportedly provides a more uniform temperatureprovides a more uniform temperature distribution throughout the muffle and allowsdistribution throughout the muffle and allows the work to be completely surrounded by thethe work to be completely surrounded by the heating elements.heating elements. www.indiandentalacademy.comwww.indiandentalacademy.com
    126. 126. PORCELAIN CONDENSATIONPORCELAIN CONDENSATION • Capillary action.Capillary action. • Vibration.Vibration. • Spatulation.Spatulation. • Whipping.Whipping. • Dry powder addition.Dry powder addition.www.indiandentalacademy.comwww.indiandentalacademy.com
    127. 127. CAPILLARY ACTIONCAPILLARY ACTION • The technique of bottling a wet build up withThe technique of bottling a wet build up with absorbent paper uses surface tension to withabsorbent paper uses surface tension to with draw liquid and packs the porcelains particledraw liquid and packs the porcelains particle together.together. • Capillary action or surface tension aloneCapillary action or surface tension alone does not remove all available liquid.does not remove all available liquid. • The cyclic action of vibration,or whippingThe cyclic action of vibration,or whipping followed by bottling is repeated until freefollowed by bottling is repeated until free liquid can no longer be forced to the surfaceliquid can no longer be forced to the surface of porcelain.of porcelain. • Usually delicate touch require to initiate thisUsually delicate touch require to initiate this mechanism.mechanism. www.indiandentalacademy.comwww.indiandentalacademy.com
    128. 128. • An overly aggressive technique couldAn overly aggressive technique could dislodge the porcelain buildup formdislodge the porcelain buildup form underlying metal sub structure.underlying metal sub structure. www.indiandentalacademy.comwww.indiandentalacademy.com
    129. 129. VIBRATIONVIBRATION • The easiest and simplest form of vibrationThe easiest and simplest form of vibration created by passing serrated instrument overcreated by passing serrated instrument over the neck of the hemostat.the neck of the hemostat. • If the restoration is left on the cast,the entireIf the restoration is left on the cast,the entire cast can be tapped or vibrated.cast can be tapped or vibrated. • Whether the restoration is vibrated onWhether the restoration is vibrated on hemostat or on cast the end result ofhemostat or on cast the end result of vibration will be to force the excess water tovibration will be to force the excess water to the porcelain surface.the porcelain surface. • At this point, with the help of tissue paperAt this point, with the help of tissue paper the surface liquid is removed.the surface liquid is removed.www.indiandentalacademy.comwww.indiandentalacademy.com
    130. 130. • There several devices to provideThere several devices to provide mechanical vibration such as, vibratingmechanical vibration such as, vibrating brushes, spatulas,and ultrasonicbrushes, spatulas,and ultrasonic condensers.condensers. • Surface tension is the force that causes allSurface tension is the force that causes all liquids to contract to their smallest possibleliquids to contract to their smallest possible surface area.surface area. • This property accounts for theThis property accounts for the transformation of the water droplets in to thetransformation of the water droplets in to the spherical mass.spherical mass. • In a wet bulk of porcelain, this force helps toIn a wet bulk of porcelain, this force helps to pack the porcelain more tightly whenpack the porcelain more tightly when www.indiandentalacademy.comwww.indiandentalacademy.com
    131. 131. SPATULATIONSPATULATION • With this form of condensation,a spatula orWith this form of condensation,a spatula or porcelain carver is used to apply,rub theporcelain carver is used to apply,rub the porcelain buildup to force the liquid to theporcelain buildup to force the liquid to the surface.surface. • This technique brings with it a greaterThis technique brings with it a greater likelihood of porcelain dislodgement,likelihood of porcelain dislodgement, particularly if too much pressure is usedparticularly if too much pressure is used especially with initial build up.especially with initial build up. www.indiandentalacademy.comwww.indiandentalacademy.com
    132. 132. WHIPPINGWHIPPING • This method actually be nothing more thanThis method actually be nothing more than variation of vibration technique.variation of vibration technique. • As the porcelain built up, a no. 10 sableAs the porcelain built up, a no. 10 sable brush is rapidly moved over the porcelainbrush is rapidly moved over the porcelain surface with a whipping motion.the whippingsurface with a whipping motion.the whipping action brings the liquid to the out sideaction brings the liquid to the out side surface of the bottling.surface of the bottling. www.indiandentalacademy.comwww.indiandentalacademy.com
    133. 133. DRY POWDWER ADDITIONDRY POWDWER ADDITION:: • This method is less widely used.This method is less widely used. • This technique also referred as brushThis technique also referred as brush application method.application method. • Dry porcelain powder sprayed over the wetDry porcelain powder sprayed over the wet porcelain surface.porcelain surface. • This uses the existing liquid to moisten theThis uses the existing liquid to moisten the powder addition.powder addition. www.indiandentalacademy.comwww.indiandentalacademy.com
    134. 134. POCELAIN APPLICATIONPOCELAIN APPLICATION METHODS.METHODS. www.indiandentalacademy.comwww.indiandentalacademy.com
    135. 135. OPAQUE PORCELIANOPAQUE PORCELIAN APPLICATION.APPLICATION. www.indiandentalacademy.comwww.indiandentalacademy.com
    136. 136. GLASS ROD TECHNIQUEGLASS ROD TECHNIQUE • First, lightly wet theFirst, lightly wet the oxidized metal metaloxidized metal metal substructure to be veneered with distilledsubstructure to be veneered with distilled water and gently vibrate the casting forwater and gently vibrate the casting for thorough wetting.thorough wetting. www.indiandentalacademy.comwww.indiandentalacademy.com
    137. 137. • Use point end ofUse point end of glass rod to apply theglass rod to apply the opaqueopaque porcelain.begin theporcelain.begin the opaquing mostopaquing most convex portion of theconvex portion of the metal.metal. www.indiandentalacademy.comwww.indiandentalacademy.com
    138. 138. • Move the opaqueMove the opaque towards the porcelaintowards the porcelain metal junction frommetal junction from one inter proximalone inter proximal area to to other &area to to other & cover the incisal area.cover the incisal area. www.indiandentalacademy.comwww.indiandentalacademy.com
    139. 139. • Lightly tap theLightly tap the hemostat with metalhemostat with metal instrument toinstrument to condense the opaquecondense the opaque porcelain and excessporcelain and excess opaquing liquid willopaquing liquid will raise to the surface.raise to the surface. www.indiandentalacademy.comwww.indiandentalacademy.com
    140. 140. • Place the edge ofPlace the edge of tissue,against the antissue,against the an edge of the moistedge of the moist opaque porcelain.holdopaque porcelain.hold the tissue in placethe tissue in place until the liquid isuntil the liquid is absorbed and takesabsorbed and takes on a dull appearance.on a dull appearance. www.indiandentalacademy.comwww.indiandentalacademy.com
    141. 141. • Blend the opaque atBlend the opaque at the porcelain metalthe porcelain metal junction to establish ajunction to establish a gradual transitiongradual transition from opaque tofrom opaque to external surface.external surface. www.indiandentalacademy.comwww.indiandentalacademy.com
    142. 142. BRUSH TECHNIQUEBRUSH TECHNIQUE • Opaque can also beOpaque can also be applied with theapplied with the brush.load the brushbrush.load the brush tip with opaquetip with opaque porcelain and carry itporcelain and carry it to the coping.to the coping. www.indiandentalacademy.comwww.indiandentalacademy.com
    143. 143. • Application of theApplication of the opaque twice is alsoopaque twice is also recommended.initiallyrecommended.initially thin layer of thethin layer of the opaque and completeopaque and complete masking is followed.masking is followed. www.indiandentalacademy.comwww.indiandentalacademy.com
    144. 144. DENTIN APPLICATIONDENTIN APPLICATION METHOD.METHOD. www.indiandentalacademy.comwww.indiandentalacademy.com
    145. 145. • Carefully return theCarefully return the cleaned,opaquedcleaned,opaqued coping to the mastercoping to the master cast.place foldedcast.place folded tissue or bottlingtissue or bottling paper on the lingualpaper on the lingual side of theside of the restoration.restoration. www.indiandentalacademy.comwww.indiandentalacademy.com
    146. 146. • To minimize theTo minimize the potential for entrappingpotential for entrapping air in the porcelain,air in the porcelain, move the tip of themove the tip of the pointed brush throughpointed brush through the mixed dentinthe mixed dentin porcelain.remove theporcelain.remove the brush with dentinbrush with dentin porcelain captured onporcelain captured on the brush tip.the brush tip. www.indiandentalacademy.comwww.indiandentalacademy.com
    147. 147. • Apply the porcelain toApply the porcelain to the most convex areathe most convex area on the restoration.on the restoration. www.indiandentalacademy.comwww.indiandentalacademy.com
    148. 148. • Gently push theGently push the porcelain to theporcelain to the intrproximal,incisalintrproximal,incisal areas.areas. www.indiandentalacademy.comwww.indiandentalacademy.com
    149. 149. • Move the porcelainMove the porcelain down to the incisaldown to the incisal edge and lightly blotedge and lightly blot the build up tothe build up to condense thecondense the porcelain on theporcelain on the substructure.substructure. www.indiandentalacademy.comwww.indiandentalacademy.com
    150. 150. • To create the mesial-To create the mesial- facial line angle,wipefacial line angle,wipe the brush to dry itthe brush to dry it slightly and reduceslightly and reduce the pointing thenthe pointing then lightly move from thelightly move from the mesial gingival areamesial gingival area to mesial-incisal area.to mesial-incisal area. www.indiandentalacademy.comwww.indiandentalacademy.com
    151. 151. • Point the brush andPoint the brush and add additional dentinadd additional dentin porcelain to lingualporcelain to lingual aspect of the incisalaspect of the incisal edge.smooth andedge.smooth and condense the incisalcondense the incisal edge from the lingualedge from the lingual and facial aspects.and facial aspects. www.indiandentalacademy.comwww.indiandentalacademy.com
    152. 152. www.indiandentalacademy.comwww.indiandentalacademy.com
    153. 153. www.indiandentalacademy.comwww.indiandentalacademy.com
    154. 154. • Use a razor knife toUse a razor knife to cut back the incisalcut back the incisal edge from betweenedge from between 1.0to1.5mm1.0to1.5mm www.indiandentalacademy.comwww.indiandentalacademy.com
    155. 155. • Remove dentinRemove dentin porcelain at theporcelain at the mesial inter proximalmesial inter proximal line angle.extend theline angle.extend the cut to the junction ofcut to the junction of the middle andthe middle and gingival 1/3gingival 1/3rdrd forfor younger patients.younger patients. www.indiandentalacademy.comwww.indiandentalacademy.com
    156. 156. • At the distalAt the distal intrproximal lineintrproximal line angle,make a cutangle,make a cut form the incisal edgeform the incisal edge towards the gingivaltowards the gingival 1/31/3rdrd as far as requiredas far as required for the esthetics.for the esthetics. www.indiandentalacademy.comwww.indiandentalacademy.com
    157. 157. • Examine theExamine the restoration from anrestoration from an incisal view forincisal view for symmetry andsymmetry and adequacy of the cutadequacy of the cut back.back. www.indiandentalacademy.comwww.indiandentalacademy.com
    158. 158. ENAMEL APPLIACTIONENAMEL APPLIACTION METHODS.METHODS. www.indiandentalacademy.comwww.indiandentalacademy.com
    159. 159. • With pointedWith pointed brush,apply enamelbrush,apply enamel porcelain to oneporcelain to one corner of cutback.corner of cutback. www.indiandentalacademy.comwww.indiandentalacademy.com
    160. 160. • Add more enamelAdd more enamel porcelain and move itporcelain and move it across the facialacross the facial surface in the incisalsurface in the incisal one third.one third. www.indiandentalacademy.comwww.indiandentalacademy.com
    161. 161. • Blend the enamelBlend the enamel porcelain at theporcelain at the junction of middle andjunction of middle and gingival 1/3gingival 1/3rdrd &begin&begin to establish the incisalto establish the incisal edge & condense theedge & condense the porcelain by blottingporcelain by blotting periodically.periodically. www.indiandentalacademy.comwww.indiandentalacademy.com
    162. 162. • Blend the enamelBlend the enamel porcelain into gingivalporcelain into gingival 1/31/3rdrd on the facialon the facial surface.Recreate thesurface.Recreate the interproximal contoursinterproximal contours and line angles.and line angles. www.indiandentalacademy.comwww.indiandentalacademy.com
    163. 163. • Shape the mesial-Shape the mesial- incisal corner asincisal corner as required for eachrequired for each case.examine thecase.examine the build up form incisalbuild up form incisal view&evaluate theview&evaluate the overall shape .overall shape . www.indiandentalacademy.comwww.indiandentalacademy.com
    164. 164. ALTERNATIVE BUILD UPALTERNATIVE BUILD UP TECHNIQUE.TECHNIQUE. www.indiandentalacademy.comwww.indiandentalacademy.com
    165. 165. • Apply the opaque toApply the opaque to mask the underlyingmask the underlying metal.metal. www.indiandentalacademy.comwww.indiandentalacademy.com
    166. 166. • Complete & smoothComplete & smooth the dentin buildup.the dentin buildup. www.indiandentalacademy.comwww.indiandentalacademy.com
    167. 167. • Create threeCreate three developmental lobesdevelopmental lobes with the pointedwith the pointed brush.brush. www.indiandentalacademy.comwww.indiandentalacademy.com
    168. 168. • Invert the cast &Invert the cast & place translucentplace translucent porcelain in the twoporcelain in the two developmentaldevelopmental groove.apply enamelgroove.apply enamel porcelain to the interporcelain to the inter proximal areas.proximal areas. www.indiandentalacademy.comwww.indiandentalacademy.com
    169. 169. • Continue this processContinue this process until the entire crownuntil the entire crown is built to full contour.is built to full contour. www.indiandentalacademy.comwww.indiandentalacademy.com
    170. 170. • Finally, use theFinally, use the whipping brush towhipping brush to gently smooth thegently smooth the entire porcelain buildentire porcelain build up.up. www.indiandentalacademy.comwww.indiandentalacademy.com
    171. 171. • Once the porcelainOnce the porcelain has been fired,youhas been fired,you should be able toshould be able to observeobserve demonstrabledemonstrable mamelons in themamelons in the restoration.restoration. www.indiandentalacademy.comwww.indiandentalacademy.com
    172. 172. PORCELAIN APLICATIONPORCELAIN APLICATION FORFOR FIXED PARTIAL DENTURE.FIXED PARTIAL DENTURE. www.indiandentalacademy.comwww.indiandentalacademy.com
    173. 173. • Apply and condenseApply and condense opaqueopaque porcelain.Cover anyporcelain.Cover any gray areas,and firegray areas,and fire the prosthesis.the prosthesis. www.indiandentalacademy.comwww.indiandentalacademy.com
    174. 174. • Return the opaquedReturn the opaqued FPD to the masterFPD to the master cast with a piece ofcast with a piece of tissue paper cut totissue paper cut to cover the entire ponticcover the entire pontic area.area. www.indiandentalacademy.comwww.indiandentalacademy.com
    175. 175. • Add a small portion ofAdd a small portion of dentin porcelain to thedentin porcelain to the under side of theunder side of the pontic on the FPDpontic on the FPD frame work.frame work. www.indiandentalacademy.comwww.indiandentalacademy.com
    176. 176. • Return the frame workReturn the frame work to the master cast andto the master cast and gently rock it back andgently rock it back and forth until it seatsforth until it seats completely.Remove thecompletely.Remove the frame work and inspectframe work and inspect the tissue side of thethe tissue side of the pontic.this area shouldpontic.this area should cover completely withcover completely with porcelain and wellporcelain and well condensed.condensed. www.indiandentalacademy.comwww.indiandentalacademy.com
    177. 177. • Place the frame workPlace the frame work back on the masterback on the master cast and apply dentincast and apply dentin porcelain or add andporcelain or add and condense opacouscondense opacous dentin to the cervicaldentin to the cervical areas of the threeareas of the three components.components. www.indiandentalacademy.comwww.indiandentalacademy.com
    178. 178. • Complete the dentinComplete the dentin build up.build up. www.indiandentalacademy.comwww.indiandentalacademy.com
    179. 179. • Create theCreate the developmentaldevelopmental lobes.Use thin razorlobes.Use thin razor knife to cut throughknife to cut through inter proximal areasinter proximal areas and individualize theand individualize the teeth.teeth. www.indiandentalacademy.comwww.indiandentalacademy.com
    180. 180. • Add enamelAdd enamel veneering material.veneering material. www.indiandentalacademy.comwww.indiandentalacademy.com
    181. 181. • Condense theCondense the porcelain build up.porcelain build up. www.indiandentalacademy.comwww.indiandentalacademy.com
    182. 182. • Measure the mesial-Measure the mesial- distal width of eachdistal width of each tooth with atooth with a BBoleyoley gauge.compare thatgauge.compare that measurement withmeasurement with porcelain build up.porcelain build up. www.indiandentalacademy.comwww.indiandentalacademy.com
    183. 183. • Use a knife or otherUse a knife or other instrument to makeinstrument to make any necessaryany necessary adjustments in theadjustments in the mesial-distal width.mesial-distal width. www.indiandentalacademy.comwww.indiandentalacademy.com
    184. 184. • Facial view of theFacial view of the build up.build up. www.indiandentalacademy.comwww.indiandentalacademy.com
    185. 185. • Lingual view of theLingual view of the build up.build up. www.indiandentalacademy.comwww.indiandentalacademy.com
    186. 186. • Three unit FPD afterThree unit FPD after firing.firing. www.indiandentalacademy.comwww.indiandentalacademy.com
    187. 187. FIRING PROCEDURES.FIRING PROCEDURES. • The large bulk of the build up will requireThe large bulk of the build up will require more time to dry and pre heat than themore time to dry and pre heat than the opaque porcelain.opaque porcelain. • Put the restoration on saggar tray place it onPut the restoration on saggar tray place it on the muffle stand of the furnace.the muffle stand of the furnace. • Properly matured porcelain have a slightlyProperly matured porcelain have a slightly orange peel appearance when firedorange peel appearance when fired correctly.correctly. • Do not under fire the porcelain.porcelain thatDo not under fire the porcelain.porcelain that has not matured properly has no shine tohas not matured properly has no shine to the surface & internally has cloudythe surface & internally has cloudywww.indiandentalacademy.comwww.indiandentalacademy.com
    188. 188. • Restorations that are under fired porcelainRestorations that are under fired porcelain often have to be stripped form metal andoften have to be stripped form metal and rebuilt.rebuilt. • Over fired porcelains appears to be glazedOver fired porcelains appears to be glazed and the surface has little or none of theand the surface has little or none of the pebbly appearance.pebbly appearance. • The firing temperature is usually lowered 10The firing temperature is usually lowered 10 degrees with each correction firing, so thatdegrees with each correction firing, so that initial build up does not get affected.initial build up does not get affected. www.indiandentalacademy.comwww.indiandentalacademy.com
    189. 189. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.comwww.indiandentalacademy.com

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