CERAMO-METAL ALLOYSCERAMO-METAL ALLOYS

Stephen C. BayneStephen C. Bayne

Department of Operative DentistryDepartment of Operative DentistrySchool of DentistrySchool of DentistryUniversity of North CarolinaUniversity of North CarolinaChapel Hill, NC 27599-7450Chapel Hill, NC 27599-7450

http://www.dent.unc.edu/portfolios/bayne/dental-materials/http://www.dent.unc.edu/portfolios/bayne/dental-materials/

PFM FABRICATIONPFM FABRICATION

vitrification

vitrification

PROCESSING CYCLESPROCESSING CYCLES

inve

stm

ent

TIME

all

oy

Alloy LCTE = 16-18 ppm/C

CASTCASTGOLDGOLDALLOYSALLOYS

Tm 890C

Trt

inve

stm

ent

Porcelain and Alloy LCTE = 14.4 ppm/C

CERAMOCERAMOMETALMETALALLOYSALLOYS

low

fu

sin

g p

orc

elai

n

TIME

Tm 1100-1500C

Trt

Tvitrification

Tg

ductile

brittle

residualvitrificationporosity

coolingshrinkageporosity

Opaque + 2-3 Body Layers

all

oy

HISTORICAL BACKGROUNDHISTORICAL BACKGROUNDA.A. Historical Review of Porcelain Use in DentistryHistorical Review of Porcelain Use in Dentistry::

1806- 1806- Fonzi prepared porcelain teeth with baked in Pt Fonzi prepared porcelain teeth with baked in Pt postsposts1817- 1817- Plantous introduces porcelain teeth to the USPlantous introduces porcelain teeth to the US1844- 1844- SS White begins large scale production of SS White begins large scale production of porcelain in USporcelain in US1854- 1854- Loomis patents the totally porcelain dentureLoomis patents the totally porcelain denture1884- 1884- Logan makes porcelain crown with baked Pt Logan makes porcelain crown with baked Pt metal postmetal post1889- 1889- Land develops the all porcelain jacket crownLand develops the all porcelain jacket crown1957- 1957- First P/M restorationsFirst P/M restorations1959- 1959- WeinsteinWeinstein patents the P/M process for dentistrypatents the P/M process for dentistry

B.B. Historical Review of Casting Alloys in DentistryHistorical Review of Casting Alloys in Dentistry::

1870- 1870- Cast restorations produced from gold coinsCast restorations produced from gold coins1907- 1907- TaggartTaggart introduces a inlay casting technique introduces a inlay casting technique 1940- 1940- Bronze alloys replace casting gold alloys during Bronze alloys replace casting gold alloys during the warthe war1968- 1968- US allows US allows price of goldprice of gold to fluctuate on the open to fluctuate on the open marketmarket1970- 1970- Large scale introduction of Large scale introduction of goldgold substitutesubstitute alloysalloys

MAJOR PFM ALLOY REQUIREMENTSMAJOR PFM ALLOY REQUIREMENTS1.1. PhysicalPhysical Properties: Properties:

a.a. HighHigh fusingfusing temperaturetemperature to prevent distortion in porcelain bake to prevent distortion in porcelain bakeb.b. MatchedMatched LCTELCTE of porcelain and metal of porcelain and metal

2.2. ChemicalChemical Properties: Properties:a.a. ChemicalChemical bondingbonding between porcelain and oxide layer on metal between porcelain and oxide layer on metal

b.b. Chemical Chemical corrosioncorrosion resistanceresistance (no tarnish) (no tarnish)c.c. Electrochemical corrosion resistanceElectrochemical corrosion resistanced.d. No porcelain discoloration reactionsNo porcelain discoloration reactions

3.3. MechanicalMechanical Properties: Properties:a.a. HighHigh EE (= stiffness) ( (= stiffness) (e.g.,e.g., E = 90 to 220 GPa) (Space for ceramic E = 90 to 220 GPa) (Space for ceramic

esthetics, but metal thickness for rigidity)esthetics, but metal thickness for rigidity)b.b. High Hardness (H = 125- 465 kg/mmHigh Hardness (H = 125- 465 kg/mm22))

(Need metal to be capable of being ground and polished)(Need metal to be capable of being ground and polished)

4.4. BiologicalBiological Properties: Properties:a.a. Non-toxicNon-toxicb.b. Non-irritatingNon-irritating

CLASSIFICATION OF ALLOYSCLASSIFICATION OF ALLOYS

1.1. Full Gold Crown and Bridge Alloys (Full Gold Crown and Bridge Alloys (REVIEWREVIEW of precious alloys) of precious alloys)

a.a. ADA Classification System (see phase diagrams)ADA Classification System (see phase diagrams)(1)(1) Type IType I 83% Au+ 83% Au+ (Non-heat hardenable)(Non-heat hardenable) -- inlay-- inlay(2)(2) Type IIType II 78% Au+ 78% Au+ (Non-heat hardenable)(Non-heat hardenable) -- inlay, onlay, …-- inlay, onlay, …(3)(3) Type IIIType III 78% Au+ 78% Au+ (Heat hardenable)(Heat hardenable) -- onlay, crown-- onlay, crown(4)(4) Type IVType IV 75% Au+ 75% Au+ (Heat hardenable)(Heat hardenable) -- crown, bridge-- crown, bridge

b.b. Effects of Alloys Components:Effects of Alloys Components:(1)(1) GoldGold (Au) (Au) (2)(2) CopperCopper (Cu) (Cu) (3)(3) SilverSilver (Ag) (Ag) (4)(4) Palladium Palladium (Pd) (Pd) (5)(5) Platinum Platinum (Pt) (Pt) (6)(6) Zinc Zinc (Zn) (Zn)

corrosion resistancecorrosion resistanceincreased hardnessincreased hardnesscounteracts orange color of coppercounteracts orange color of copperincreased MP and hardnessincreased MP and hardnessincreased MPincreased MPoxygen scavengeroxygen scavenger

2.2. Other Crown and Bridge Casting Alloys:Other Crown and Bridge Casting Alloys:

a.a. ADA Classification System (see phase diagrams)ADA Classification System (see phase diagrams)(1)(1) High gold alloys (IMMUNE)High gold alloys (IMMUNE)

(a)(a) Au-Pt-PdAu-Pt-Pd(b)(b) Au-Pd-AgAu-Pd-Ag

(2)(2) Low gold alloys (SEMI-IMMUNE)Low gold alloys (SEMI-IMMUNE)(3)(3) Gold-substitute alloys (PASSIVE)Gold-substitute alloys (PASSIVE)

(a)(a) Ag-Pd (85% of all PFM alloys)Ag-Pd (85% of all PFM alloys)(b)(b) Pd-XPd-X

(4)(4) Base-metal alloys (PASSIVE)Base-metal alloys (PASSIVE)(a)(a) Ni-Cr (with or without Be)Ni-Cr (with or without Be)(b)(b) Co-CrCo-Cr(c)(c) Fe-CrFe-Cr

(5)(5) Titanium alloys (PASSIVE)Titanium alloys (PASSIVE)(6)(6) Other alloys – Al Bronzes, Brasses (ACTIVE)Other alloys – Al Bronzes, Brasses (ACTIVE)

CLASSIFICATION OF ALLOYSCLASSIFICATION OF ALLOYS

CO

RR

OS

ION

CO

RR

OS

ION

TIMETIME

Act

ive

Immune

Passive

Au–Pt–Pd Ni-Cr …Au-Pd-Ag Pd-Ag Pd-X

CLASSIFICATION OF ALLOYSCLASSIFICATION OF ALLOYS2.2. Other Crown and Bridge Casting Alloys (cont):Other Crown and Bridge Casting Alloys (cont):

b.b. Effects of Alloying Components in Effects of Alloying Components in Gold AlloysGold Alloys::(1)(1) Au, Ag, Pd, PtAu, Ag, Pd, Pt (2)(2) PtPt (3)(3) PdPd (4)(4) AgAg (5)(5) Fe, In, SnFe, In, Sn (6)(6) ZnZn

c.c. Effects of Alloying Components in Effects of Alloying Components in Other AlloysOther Alloys::(1)(1) Cr, TiCr, Ti (2)(2) Ni, Co, FeNi, Co, Fe

corrosion resistanceincreased MPincreased MP and hardnesscheaperoxide formers for gold alloysoxygen scavenger

oxide formers in other alloysincreased modulus

metal oxide

opaque body

SPECIAL TERMINOLOGYSPECIAL TERMINOLOGY

1.1. Color of Alloys:Color of Alloys:a.a. White GoldWhite Gold = White color due to higher concentration of Pt or Pd. = White color due to higher concentration of Pt or Pd.b.b. Yellow GoldYellow Gold = yellow color due to presence of copper and/or gold. = yellow color due to presence of copper and/or gold.

2.2. Synonyms for Ceramic-Metal Restorations:Synonyms for Ceramic-Metal Restorations:a.a. Porcelain Fused to Metal (PFM)Porcelain Fused to Metal (PFM)b.b. Porcelain Bonded to Metal (PBM)Porcelain Bonded to Metal (PBM)c.c. Ceramo-Metal RestorationsCeramo-Metal Restorationsd.d. Porcelain-Metal Restorations (P/M)Porcelain-Metal Restorations (P/M)

PROPERTIES of Ceramo-Metal AlloysPROPERTIES of Ceramo-Metal Alloys

TTmm((°C)°C) KHN,BHNKHN,BHN

Au-Pt-PdAu-Pt-Pd 11201120 165165Au-Pd-AgAu-Pd-Ag 11801180 200200

Pd-AgPd-Ag 11001100 170170Pd-XPd-X 13401340 260260

Ni-CrNi-Cr 13201320 250-300250-300Co-CrCo-Cr - - -- - - - - -- - -Fe-CrFe-Cr - - -- - - - - -- - -

COMMERCIAL EXAMPLESCOMMERCIAL EXAMPLES

Au-Pt-PdAu-Pt-PdAu-Pd-AgAu-Pd-Ag

Pd-AgPd-AgPd-XPd-X

Ni-CrNi-CrCo-CrCo-CrFe-CrFe-Cr

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