Ceramic gold alloys seminar - American Prosthodontic Society...• (1) An object at or near finished...

Ceramic gold alloys seminar

Presented by,

Jose “Paco” Cortes-Botello, D.D.S.

University of Texas Health Science Center San Antonio

Assistant Professor

American Prosthodontic Society Membership Committee Chair and Executive Council

1 Dr. Jose "Paco" Cortes-Botello

Overview.

• Introduction. • History. • Physical properties. • Chemical properties. • Classification. • Literature Review. • Summary.


Introduction.


Metallurgy.

• Science and technology of metals and alloys. • Process metallurgy: extraction and refining. • Physical metallurgy: physical properties. • Mechanical metallurgy: with the response of metals to applied

forces.


Alloy.

• Metallic material formed by the combination of 2 or more metals; or 1 or more metals with a nonmetal.

• Au and Pd are soluble in each other. • Cu and Ag are not.

Wataha, JPD 2002;87:4, 351-363.


Why alloys?

• Enhance: – Physical properties. – Chemical properties. – Biological properties.

• Steel: is an alloy of carbon in iron. • Stainless steel: steel plus chromium and nickel.

Wataha, JPD 2002;87:4, 351-363.


History.


History.

• Before 1975, 3 distinct alloy groups. • Alloys for full-cast restorations. • Alloys for metal-ceramic restorations. • Alloys for removable partial denture frameworks.

Wataha, JPD 2002;87:4, 351-363. Eastman Dental Dispensary Building, 1950.


History.

Alloys for metal-ceramic restorations. • Require melting ranges (MR) that could stand porcelain application.

(870ºC-1370ºC) • Higher content of Pd MR. • Ag was avoided greening porcelain.

Alloys for RPD frameworks. • Added 0.5-1% C to increase hardness and strength.

• Formation of carbides.

Wataha, JPD 2002;87:4, 351-363. 9 Dr. Jose "Paco" Cortes-Botello

History.

• Au 1969 $35/oz, 1980 $800/oz, November 2005 $495/oz * • Pd 1980 $150/oz, 2000 $1000/oz, November 2005 $267/oz *

$0

$200

$400

$600

$800

$1,000

$1,200

1969 1980 2000 2005

AuPd

*www.kitco.com 10 Dr. Jose "Paco" Cortes-Botello

Precious or Noble?

• Precious refers to specific group of 8 elements: Au, Ag, Pt, Pd, Rh, Ru, Ir, Os.

• Noble refers to zero based electrode, elements below hydrogen. Includes all the precious metals.

Goldfogel and Nielsen. JPD 1982;48:3, 340-343. 11 Dr. Jose "Paco" Cortes-Botello

Precious or Noble?

• Nobility is the free energy of chemical reactions corrosion.

• Inertness is referred to the tendency of the metals not to form oxides of sulfides.

• Passivity, “partially nobility” is the inertness provided by a thin oxide or sulfide tenacious, transparent and completely insoluble layer in the surface of the metal.

Goldfogel and Nielsen. JPD 1982;48:3, 340-343.


Physical properties.



• N = kg (m/s²) – A newton is the amount of force required to accelerate a mass of one kilogram at a rate of

one meter per second squared.

• Pa = N/m² = kg (m/s²) / m² – A pascal is the unit of pressure = one Newton per square metre. – 1 megapascal (MPa) = 1 000 000 Pa = 1 N/mm²

• Kg/mm²

– Unit of Vickers's Hardness.


Yield strength.

• The stress required to permanently deform an alloy a standard amount (0.2%); to go from elastic to plastic deformation. (MPa)

• Elongation: the amount of permanent deformation an alloy can endure before tensile fracture. Stiffness or rigidity (%)

Wataha, JPD 2002;87:4, 351-363.

Yield strength Elongation


Elastic modulus.

• Young's modulus, modulus of elasticity or tensile modulus. • Is a measure of the stiffness of a given material, defined as the limit for

elastic deformation. (MPa)

Elastic Modulus


Hardness.

• Resistance to wear. Vickers hardness. (kg/mm²) • Must be enough to resist occlusal forces but not excessive to wear

opposing teeth. • Enamel hardness = 340 kg/mm²

Wataha, JPD 2002;87:4, 351-363.

M-90 $58,000 * NEWAGE, INC.

* www.hardnesstesters.com 17 Dr. Jose "Paco" Cortes-Botello

http://www.hardnesstesters.com/mt90-microhardness-tester.htm

Hardness.

• Diamond is a transparent crystal of pure carbon consisting of tetrahedrally bonded carbon atoms.

• Aggregated diamond nanorods (Natalia Dubrovinskaia, at the University of

Bayreuth, Germany in 2005).

Unit cell of a diamond

Carat Cost per carat Total cost US$ 0.5 (50 points) $3000 $1500 1.0 $6500 $6500 1.5 $8500 $12,750 2.0 $13,000 $26,000 3.0 $17,000 $51,000 5.0 $23,000 $115,000

1 carat = 200mg


http://en.wikipedia.org/wiki/Image:Diamond_Cubic-F_lattice_animation.gif

Grain size.

• Molten alloy cools forming microscopic crystals (grains) and spaces between them called grain boundaries.

• Smaller the grain, higher tensile strength. • Grain size does not affect hardness. • Iridium 50ppm to refine Au. • Ruthenium 0.5% to refine Pd.

• Optimal Grain size 30µm.

Wataha, JPD 2002;87:4, 351-363.

High noble alloy, etched (100x) Grain size = 10µm


Phase structure or microstructure.

• Single Phase. Homogeneous. Elements soluble. Au, Pd, Cu. Less corrosion. Easier to manipulate.

• Multiple Phase. Heterogeneous. Not completely soluble. Au, Pt. Higher corrosion. Can be etched.

Wataha, JPD 2002;87:4, 351-363.

1000 x


Malleability.

• The property of a metal to be deformed by compression loads without cracking or rupturing. Material will be suitable for forging or rolling into thin sheet.

Brown and Curtis. Dent Mat 1992, 325-328. 21 Dr. Jose "Paco" Cortes-Botello

Chemical Properties.


Corrosion. • Deterioration of the properties in a material due to reactions with its

environment. (release elements). • Compromise physical properties. (strength and esthetics) • Biological irritation. (Biocompatibility)

• Multiple phase alloys and non-noble elements risk. • Noble elements: Au, Pt, Pd, Ir, Rh, Os, Ru.

Wataha, JPD 2002;87:4, 351-363.


Oxidation.

• High Au alloys have thinner, light color oxide.

• Ag, Ni, Co alloys have thicker, darker oxide. • Thicker opaque layer, lower value in porcelain. • Thicker oxide Higher risk MC bonding failure. • Stress from occlusal loads oxide layer.

• Recasting Au alloys, the oxide-forming elements are depleted from 1st

casting and produce inadequate oxide layer.


Coefficient of thermal expansion. (CTE) • The ratio of change in length, area, or volume per degree to the

corresponding value at a standard temperature.

• P contracts , tensile stress. • P contracts , compressive stress. • P CTE < A CTE 0.5 x 10ˉ / ºC.

• If P CTE <<<< A CTE, MC bonding will fail as a result of compressive stress.

Wataha, JPD 2002;87:4, 351-363.

6


Melting range. • The range of temperature (T) between:

• Solidus T: lower T at which melting begins. • Liquidus T: higher T at which entire alloy is melted.

• Porcelain must sinters 50 ºC < alloy’s solidus T. • Solder must have liquidus T 50ºC < alloy’s solidus T.


http://www.nodaya-net.com/interior/melting-a.jpg

Classification.


ADA Classification, 1984.

• Composition. • Amount of Au and noble

metals. • Corrosion.

• Physical properties. • Hardness • Yield strength • Elongation

Wataha, JPD 2002;87:4, 351-363.

CLASS Composition wt %.

High Noble Au >40% Noble metal >60%

Noble Noble metal >25%

Base-metal Noble metal < 25%

ADA Hardness Clinical use Yield strength

Elongation

I Soft Inlay <140 MPa 18%

II Medium Inlay, onlay 140 - 200 18%

III Hard Full crown, short FPD

201 - 340 12%

IV Extra Hard Long FPD RPD framework

>340 10%


High noble.

• Single phase (low corrosion). • Favorable manipulation (cut, finish and polish). • Light color oxide, easier to mask.

• Low strength. • Higher Cost.

Wataha, JPD 2002;87:4, 351-363.

Subclass Clinical use Vickers hardness Kg/mm²

Yield Strength MPa

Au 85%, Pt Full cast, MC. 165 580

Au 52%, Pd, In, Ga

Full cast, MC 280 385

Au 72%, Cu, Ag Full cast. 210 450


Noble.

• Harder alloys. • Higher strength. • Thicker oxide layer. • Lower cost.

• Multiple phase. • Higher corrosion, Cu, Ag. • Manipulation is difficult.

Subclass. Use Vickers hardness Kg/mm²

Yield Strength, MPa

Au, Pd, Cu, Ag Full cast. 250 690

Pd, Cu, Ga Full cast, MC, long span FPD.

280 580

Pd, Ag Full cast, MC. 275 620

Wataha, JPD 2002;87:4, 351-363.


Base-metal alloys.

• Hardest alloys. • Higher yield strength. • Lowest cost.

• Multiple phase, higher corrosion. • Highest melting ranges. (margin) • Very difficult manipulation.

Wataha, JPD 2002;87:4, 351-363.

Subclass Use Vickers hardness Kg/mm²

Yield Strength, MPa

Ni, Cr, Be, C MC, RPD. 350 825

Ni, Cr Full cast, MC, RPD.

350 310

Co, Cr RPD 390 310

Ti MC, RPD. 400


Purpose Disadvantages Au Nobility Hardness Pd Nobility, Higher MR, Hardness Oxide, grayness. Ag Increases solubility of elements (single phase)

Hardness Thick oxide, greening.

Cu Increases strength Low solubility (multiple phase) Co Increases strength Low solubility Ga Oxide for porcelain bonding Low solubility In Oxide for porcelain bonding Low solubility Ni Hardness Carcinogenic, allergenic Cr Strength, hardness. Extremely reactive, oxides. Be Reduce MR Corrosion, carcinogenic Ru Refiner 0.5% High MP 2310 ºC Ir Refiner 50 ppm High MP 2410 ºC Zn Increase hardness Multiple phase

Brown and Curtis. Dent Mat 1992, 325-328. 32 Dr. Jose "Paco" Cortes-Botello

Casting.

• (1) An object at or near finished shape obtained by solidification of a substance in a mold.

• (2) Pouring molten metal into a mold to produce an object of desired shape.


Literature review.


Corrosion.


Corrosion of Pd alloys.

• Corrosion resistance. • Effect of preoxidation on their corrosion resistance. • Cytotoxicity. • Biocompatibility. • Element analysis.

Syverud et al. Dental Materials 2001;17:7-13.


Materials and methods.

• Scanning Electronic Microscopy (SEM) • Element analysis • Immersion test • Cell culture test (mice fibroblasts)


x 9 x 9

10mm

32mm

1.5mm

a) *Preoxidize. b) -0.1mm. c) -0.2mm. {

*preoxidize 1010ºC, 5min.


Corrosion.

• Immersion Test: • Solution Lactic Acid and NaCl 0.1mM. • 7 days at 37ºC.

• Ph = 2.3

• Ph = 7

Results are presented in µg/cm²


SEM and element analysis.

• As casting.

• No visible oxidation.

• After preoxidation.


Option (Cu) IS85

200 x

200 x 4000 x

26 x b


Cytotoxicity.



Conclusions.

• Manufacturer's information is accurate. • Specimens from both alloys, with oxide films from preoxidation,

significantly released more ions. • Pd-Cu alloy (Option) showed higher oxidation and corrosion. • Pd Cu (1:2) was the most toxic combination. • Cu was most toxic element and released element.



Corrosion behavior of Pd and Au alloys.

• Pd alloys have been used as an alternative to Au alloys because of their physical properties and lower cost.

• Concerns about Pd corrosion remains.

• Purpose: • To measure the corrosion resistance of Pd alloys. • To compare their corrosion behavior with Au alloys.

Sun et al. JPD 2002;87:1, 86-93. 42 Dr. Jose "Paco" Cortes-Botello


• 10 Disk specimens (1.2 x 0.13 cm), 2 groups: • As cast. • Heat treated, firing cycle

– Vita porcelain

• Tested under 5 different solutions: • 0.9% NaCl (human body fluid) • 0.09% NaCl (human saliva) • Fusayama solution (artificial saliva) • N2-deaerated 0.09% NaCl. • N2-deaarated Fusayama solution.

Sun et al. JPD 2002;87:1, 86-93.

Alloy Composition Liberty Pd 76%, Cu, Ga Freedom Plus Pd 78%, Cu, Ga Legacy Pd 85%, Ga Olympia Au 52%, Pd 38.5%


Results.

• The open circuit potential (OCP) and polarization resistance (PR) were designated as the corrosion resistance.

• The great similarity in corrosion behavior for the high Pd and Au-Pd alloys was attributed to their predominant Pd content.


Results.


Conclusions.

• In vitro, corrosion resistance of the 3 high Pd alloys in simulated body fluid and oral environments were comparable to Au-Pd alloy.

• There were no significant differences among the 4 Heat Treated alloys tested in oral environments.

• 3 High Pd alloys showed passivity through a surface oxide film formation in simulated body fluids and oral environments. Corrosion occurred by dissolution of less noble elements.


Recasting alloys.


Effect of recasting on the cytotoxicity.

• Recasting common practice in many laboratories to reduce costs. • Ni-Cr and Co-Cr alloys have been used as a substitute for noble and high

noble alloys.

• To determine if recasting of base metal alloys: • Affect their cytotoxicity. • Affect their element release.

Hiyasat and Darmani. JPD 2005;93:2, 158-163. 48 Dr. Jose "Paco" Cortes-Botello


• Cell culture cytotoxicity. • Spectrophotometry to measure element release. • 5 base metal alloys. • 12 Disk specimens per alloy (3 x 5mm) divided in 3 groups.

• 100% New Metal. • 50% Recast. • 100% Recast.

Hiyasat and Darmani. JPD 2005;93:2, 158-163.

Alloy Composition Remanium CS Ni 61%, Cr 26%, Mo Wiron 99 Ni 65%, Cr 23%, Mo Wirobond C Co 65%, Cr 26%, Mo CB Soft Ni 72%, Cr, Cu Thermobond Cu 87%, Al, Fe


Results.

• Cytotoxicity: mouse fibroblasts were incubated with specimens for 3 days, 37ºC.

• Cell activity = SDH formation.


Alloy Comp.

Remanium CS Ni, Cr, Mo Wiron 99 Ni, Cr, Mo Wirobond C Co, Cr, Mo CB Soft Ni, Cr, Cu Thermobond Cu , Al, Fe

Cr, Mo Oxide. Less corrosion by passivation.


Element release in parts per billion.


Alloy Ni Cr Co Cu Mo Al Fe Remanium Ni, Cr

New. 50% R 100% R

132 206 218

13 60

21 61 54

Wiron 99 Ni, Cr

New. 50% R 100% R

214 246 264

28 28 109

Wirobond C Co, Cr

New. 50% R 100% R

269 323 546

21 116 15

CB Soft Ni, Cr, Cu

New. 50% R 100% R

435 471 501

433 539 602

Thermobond Cu, Al, Fe

New. 50% R 100% R

7457 10,650 17,848

56 74 193

22 1520 6560


Conclusions.

• Recasting of alloys at 50% and 100% as previously cast metal significantly increased cytotoxicity of base metal alloys tested.

• Element release increased proportionally with the percentage of recast alloy.

• Cu was the most cytotoxic and the most affected by recasting.

• Cr was not released in detectable amounts.

Hiyasat and Darmani. JPD 2005;93:2, 158-163. 52 Dr. Jose "Paco" Cortes-Botello

Marginal accuracy.


Christensen. JPD 1966;16:2, 297-305.

Marginal fit of gold inlay castings.

• 10 gold inlays mounted with contact points. • Clinically evaluated inlays by sight, explorer and roentgenograms by 10

faculty of University of Washington. • Least acceptable margin = 39 µm. • Gingival margins accepted = 119 µm. • Margins visually accessible were rejected = 26 µm. • Gold margins may be closed up to 2 µm.


www.xray.hmc.psu.edu/rci/ss1/ss1_2.html

Wilhelm Conrad Roentgen, 1895.

First X-ray, 1896. E. Haschek, 1896. Michael Pu, 1896.


Evaluation of alternative alloys.

• To evaluate the marginal fit of castings made of alternative alloys. • 9 alloys: 2 full crowns and 2 ¾ crowns per alloy, shoulder preparation. • Evaluated by 10 faculty of the University of Michigan.

1. Margins completely covered 2. Margins clinically acceptable, may need burnishing. 3. Questionable margins, may not be closed. 4. Clinically unacceptable.


Results.

Nitkin and Asgar. JADA 1976;93, 622-629.

Alloy Composition Total rating Rank

B-2 Au, High noble 58 1

Forticast Au 50%, Pd, Ag 59 2

Paliney CB Au 15%, Pd 20% 80 3

Alborium Au 15%, Pd 20% 100 4

Albacast 27% Pd, Ag 104 5

Aurolite CB 27% Pd, Ag 112 6

Howmedica Ni-Cr 128 7

Jelenko Exp Ni-Cr 124 8

• 40 = perfect score. •160 = worst.


Conclusions.

• Castings from type III gold alloy showed the best marginal accuracy. There was no significant difference with Au 50% gold alloy castings.

• Castings from Ni-Cr alloys were tight on dies and presented the highest marginal discrepancies. Margins were usually incomplete.

• Savings on lower cost alloy will be offset by the extra labor in grinding and adjusting alloys.

Nitkin and Asgar. JADA 1976;93, 622-629. 58 Dr. Jose "Paco" Cortes-Botello

Semiprecious vs nonprecious alloys.

• In vitro study. • Marginal accuracy

• Clinical 18 month follow up study.

• Gingival Irritation • Tooth sensitivity • Tarnish and corrosion • Abrasion

Landesman et al. JPD 1981;46:2, 161-166.

Alloy Comp Harmony Au 74%, Ag 12%, Cu 9%

Minigold Au 40%, Ag 47%, Cu 8%

WLW Pd 25%, Ag 71%

Litecast Ni 63%, Cr 20%, Co 15%


In vitro study.

• 2 Inlays, 2 onlays and 2 crowns for each alloy. • Visually inspected 25 X binocular and SEM. • No significant differences in marginal accuracy.

Landesman et al. JPD 1981;46:2, 161-166. High Au alloy x 60

Inlay

Die

Crown

Die

Pd-Ag alloy x 60


Clinical study.

• Evaluation at 3, 6, 12 and 18 months. • Index range = 1 - 4

Alloy Gingival

Irritation Sensitivity Abrasion Corrosion

Tarnish Mixed Rank

Harmony n=37

18 48%

37 100%

36 97%

29 78%

1.5

Minigold n=18

6 33%

18 100%

18 100%

12 67%

1.75

WLW n=22

11 50%

20 90%

20 90%

6 27%

2.5

Litecast n=7

2 28%

6 85%

6 85%

1 14%

4

Landesman et al. JPD 1981;46:2, 161-166. Table shows number of restorations and percentage free of defects.


Conclusions.

• No significant differences were found in marginal fit among the tested alloys in the in vitro study.

• High noble alloy (Au 74%, Ag 12%, Cu 9%) showed significant less corrosion and tarnish.

• No significant differences were found among the 4 alloys regarding gingival irritation, abrasion or sensitivity.

Landesman et al. JPD 1981;46:2, 161-166.


Marginal fit of base metal alloys.

• 3 different investments. • 5 base metal alloys. 1 gold alloy (control). • Full crown: tapered 10º and beveled shoulder. • 90 specimens; 5 castings per alloy and investment. • Evaluated with microscope at X3 magnification.

• Oversized. • Adequate. • Undersized.

Vermilyea et al. JPD 1983;50:5,651-4.


Results.

0102030405060708090

100

%

A B C D E F

Alloy

AdequateUndersized.Oversized

0

10

20

30

40

50

60

70

80

90

100

A B C D E F


0

10

20

30

40

50

60

70

80

90

100

A B C D E F


Base metal alloys A, B, C, D, E. (Biobond, Ceramalloy II, Unibond,

Biocast, Neobond II)

High noble gold alloy F. (Olympia).

Ceramigold 2 (immersed in 100ºF water)

Neoloy (bench cure) Hi Temp (immersed in 100ºF water)



Conclusions.

• Significant differences in marginal fit between the control alloy and the 5 base metal alloys.

• Marginal adaptation of base metal alloys was poor due to undersized castings.

• Investment manufacturer’s instructions will require alterations to enhance the fit of base metal castings.



Marginal accuracy of dental alloys.

• In vitro study: • To measure and compare marginal accuracy of complete metal

crowns before and after cementation. • To measure cement interface.

Tjan et al. JPD 1991;66:157-164.

ALLOY COMPOSITION

Harmony Au 74%, Ag 12%, Cu 9%

W-3 Au 49%, Pd 40%

Spirit II Plus Au 2%, Pd 80%

Duracast Cu 80%, Al 12%, Fe, Ni

Will Ceram Litecast Ni 65%, Cr 15%, Mo 14%

Elektra Pd 25%, Ag 59%, Cu 15%


Materials and methods. • 10 crowns, 5º taper, flat occlusal surface and chamfer margin. • Marginal discrepancy (MD) measured at 12 points, before and after

cemented with Zinc-phosphate cement. • 2 specimens (highest and lowest MD) from each alloy were embedded and

sectioned to measure the thickness of the cement.

Tjan et al. JPD 1991;66:157-164. 1 µm resolution.

4 layers of die spacer

Video microscope, Digimatic micrometers.


Results.

0

20

40

60

80

100

120

140

Au Au, Pd Pd Cu Ni, Cr Ag

Alloy

M.G.V.D.

Tjan et al. JPD 1991;66:157-164.

ALLOY COMPOSITION Marginal Gap b.c. Vertical discrepancy a.c.

Cement Thickness

Harmony Au 74%, Ag, Cu 9.7 11.6 22

W-3 Au 49%, Pd 40% 43 33 100

Spirit II Pd 80%, Au 45.8 6.6 45.5

Duracast Cu 80%, Al, Fe, Ni 45.2 60 145.5

Litecast Ni 65%, Cr 15%, 121.1 75 221.5

Elektra Pd 25%, Ag 59% 22.2 8 34.5

Results in µm.

µm


Conclusions.

• Type III gold alloy consistently produced most accurate marginal fit. • Ag-Pd alloy produced the closest marginal fit to gold alloy. • Ni-Cr alloy produced the poorest margins. • Dimensions of the internal relief achieved by die spacer were inconsistent

and unpredictable.

Tjan et al. JPD 1991;66:157-164. 69 Dr. Jose "Paco" Cortes-Botello

Marginal accuracy of new and recast alloys.

• Many dental laboratories combine new metal with previously cast metal in ranges that vary from 100% new metal to 50%/50%.

• Marginal accuracy is crucial for restoration success and longevity.

• Purpose: to study the compositional stability and marginal accuracy of type III gold alloy.

Ayad, JPD 2002; 87:2,162-6. 70 Dr. Jose "Paco" Cortes-Botello


• 60 cylindrical wax patterns, no spacer. • Type III alloy. Au 74%, Pd 4%, Ag 11.5%, 9.5% Cu

• Group A. 100% new metal. • Group B. 50% new + 50% recast metal. • Group C. 100% recast metal.

• Microscope x100.

• X ray energy-dispersive spectroscopy.



• 4 pairs index indentations equal distances around circumference. • Indentation position (IP1) was determined. (98N) • After adjustment, castings were cemented (98N) with Panavia and

indentation position was again determined (IP2). • Marginal discrepancy = IP1 - IP2.

• Specimens were removed, cleaned, embedded in acrylic resin and axial

cut for elemental analysis.


Results.

• Marginal discrepancy. – Less 25 µm for all groups. – Significant difference

between 3 groups.

• Composition analysis. – Au decreased significantly in

recast metal. – Pd increased.


Conclusions.

• For gold alloy type III tested, composition of Au significantly reduces with recasting of alloy.

• Marginal opening for all castings was less than 25µm.

• Lowest marginal discrepancy was obtained with 100% new metal.

• No clinically differences could be detected on the margins among the 3 groups.


Properties of Au-Pd alloys.

• 6 crown specimens were tested as cast and 6 heat treatment. • Tensile strength

• 12 discs (13mm x 3mm) • Hardness • Yield strength • Elastic limit • Elongation

• Instron Machine. • Strain Gauge Extensometer. • Vickers Metallograph. • Spectrophotometry.


Alloy Composition Olympia Au 52%, Pd 38%, In, Ga

JPW Au 49%, Pd 31%, Ag 14%

Neydium Au 49%, Pd 31%, Ag 14%


Results.


Neydium JPW Olympia

Property As cast Heat tx As cast Heat Tx As cast Heat Tx

Tensile strength * 86 97 85 100 109 115

Yield strength * 61 71 56 77 73 79

Elastic limit * 46 57 44 58 65 69

Elongation % 6 8 7 6 13 20

Hardness DPN 199 218 187 214 213 225

* Values x 1000 PSI


Results.


Neydium Au 49%, Pd 31%, Ag 14%

JPW Au 49%, Pd 31%, Ag 14%

Olympia Au 52%, Pd 38%, In, Ga



Results.

Au 49%, Pd 31%, Ag 14% A

Au 49%, Pd 31%, Ag 14% B

Au 52%, Pd 38%, In, Ga C

Heat treatment.

Magnification 450 X

5 min at 1800 ºF


Conclusions

• Hardness, tensile and yield strength of the Au-Pd alloy and Au-Pd-Ag alloys were comparable.

• 3 alloys presented homogenized structures due to their similar grain size and configuration.

• Values for Au-Pd alloy were significantly higher.

• Alloys with Ag were affected by increase temperature.

Vermilyea et al. JPD 1980;44:3,294-9. 80 Dr. Jose "Paco" Cortes-Botello

Microstructure and hardness of Pd alloys.

• Pd alloys have good mechanical properties and lower cost than Au alloys.

• Pd-Ga alloys are hard alloys difficult to manipulate by technicians and dentists.

• Purpose: Compare the Vickers hardness and microstructure of 4 palladium based alloys for metal ceramic restorations.

Vermilyea et al. J of Prosthodontics, 1996;5:4, 288-294. 81 Dr. Jose "Paco" Cortes-Botello


• 20 central incisor copings were cast for each alloy. • Microstructure: Scanning Electron Microscope (SEM). • Vickers hardness: M-400 Loading Machine:

• 1-kg/30s load (ADA Specification no. 5)

Vermilyea et al. J of Prosthodontics, 1996;5:4, 288-294.

Alloy. Composition. Freedom Pd 76%, Cu 10% Ga 7%, In 7% Legacy XT Pd 75%, Ga 6%, Ag 10%, In 6%

Accu-Star Pd 75%, Ag 6% Ga 6%, In 6%

Super-Star Pd 60%, Ag 28%, In 6%


Results.

• Tested as cast and after firing cycle:

• 1 oxidation. • 1 opaque. • 2 body. • 1 glaze.


Vickers Hardness. Manufacturer Information. Alloy. As cast. After Heat Tx. Vickers H. Yield strength Pd, Cu, Ga 345 332 360 779 Pd , Ga, Ag 249 230 240 483 Pd, Ag, Ga 261 240 260 517 Pd, Ag 263 219 280 655


SEM Results.

• Freedom • Pd, Cu, Ga

• Legacy • Pd , Ga, Ag

» Ru

• As Cast.


After Firing Cycle.


SEM Results.

• Accu-Star • Pd, Ag, Ga

• Super-Star • Pd, Ag

• As Cast.


After Firing Cycle.


Conclusions.

• After Porcelain Firing Cycle, differences in hardness were statistically significant (4%-8%) for Pd-Ga alloys. This differences have no clinical significance.

• However a 13% decrease in the hardness of the Pd-Ag alloy (Super Star) might be of clinical importance.

• Considerable homogenization of the as cast microstructure of the 4 alloys occurred with heat treatment.

Vermilyea et al. J of Prosthodontics, 1996;5:4, 288-294. 86 Dr. Jose "Paco" Cortes-Botello

Investments.


Casting ringless vs ring investment system.

• Marginal accuracy is essential for longevity: • Less plaque accumulation. • Less leakage. • Improves esthetics.

• Accuracy is affected:

• Preparation • Impression • Waxing • Casting process

Lombardas et al. JPD 2000;84:1, 25-31. 88 Dr. Jose "Paco" Cortes-Botello


• Metal die; 30 copings, high Pd alloy (Argedent 52SF): • 2.5 cm Ring, Whip Mix Hi Temp w/ Bego liner. • 3.0 cm “Ringless”, Bego Belavest. • 2.5 cm Ring, Bego Belavest.

• Gap measured at 4 points w/optical microscope by a “blind” operator.


Results.

Lombardas et al. JPD 2000;84:1, 25-31.

52% 38%

48%

25%

• 1 die of each group was internally adjusted as a pilot study. All measurements ranged between 15-30 µm.


Conclusions.

• Ringless group’s vertical margin discrepancies significantly lower than that for the 2 ring groups.

• Metal ring restricts setting and thermal expansion of the investment, which is necessary to compensate metal shrinkage due to solidification.

• Ringless technique is clinically acceptable. • Ring techniques are well documented and should not be abandoned.

Lombardas et al. JPD 2000;84:1, 25-31. 91 Dr. Jose "Paco" Cortes-Botello

Temperature and distortion.


Temperature distortion in high Pd alloys.

• Multiple variables affect the marginal fit of a cast preventing it to fit accurately, leading to bacterial plaque accumulation, caries, and gingival inflammation.

• Evaluate the distortion produced by simulated porcelain firings in 9 Pd

alloys. • Measure overall distortion. • Which part of the heat treatment produces more distortion. • Effect of an occlusal mesiodistal transverse groove in cast.

Papazoglou et al. JPD 2001;85:2,133-140. 93 Dr. Jose "Paco" Cortes-Botello

Material and methods.

Papazoglou et al. JPD 2001;85:2,133-140.

ALLOY COMPOSITION

Option Pd 78%, Cu, Ga, Au

Spartan Plus Pd 79%, Cu, Ga, Au

Liberty Pd 76%, Cu, Ga, Sn, Au

Freedom Plus Pd 78%, Cu, Ga, In, Au

Protocol Pd 75%, Ga, In, Ag, Au

Legacy XT Pd 75%, Ga, In, Ag, Au

Jelenko No. 1 Pd 78%, Ga, In, Sn, Ag

Superstar Pd 60%, Ag, In, Sn

Olympia Au 51%, Pd 38%, Ga, In




5 copings for each alloy. 0.5mm thickness. 1 mm wide margin.

Measures at 4 points at:

As cast. Oxidized, 650 ºC to 1030 ºC. 2nd opaque from 600 ºC to 990 ºC. 2nd dentin from 600 ºC to 930 ºC.

Marginal opening = d1 – d2.


Results.


ALLOY Oxidized 2nd Opaque 2nd Dentin

Option -8 -4 -3

Spartan Plus -5 -3 -1

Liberty -4 6 16

Freedom Plus -7 -5 -2

Protocol -5 -7 -8

Legacy XT -4 -3 -2

Jelenko No. 1 -15 -13 -12

Superstar -19 -11 -12

Olympia -7 -24 -7

Marginal opening = d1 – d2.

Results in µm.


Results. • Vertical gap in µm after complete heat treatment.

*values greater than the 40µm


ALLOY Vertical gap. Mesiodistal.

Vertical gap. Buccolingual.

Option 0 21 Spartan Plus 25 6 Liberty 0 0 Freedom Plus 29 13 Protocol 0 55* Legacy XT 6 12 Jelenko No. 1 128* 84* Superstar 38 87* Olympia 24 52*


Conclusions.

• Most of the selected high Pd alloys presented distortions not significantly different than those form the control Au-Pd alloy.

• Greatest distortion occurred during oxidation heating cycle.

• Mesiodistal groove did not prevent distortion for the 9 alloys.

• Distortion values were low and there are several laboratory techniques to counteract it.

Papazoglou et al. JPD 2001;85:2,133-140. 98 Dr. Jose "Paco" Cortes-Botello

Solders.


Infrared vs torch-soldering.

• Purpose of the study is to compare solder joints: • Bond strength. • Discoloration. • Fracture models.

• 2 alloys: Olympia Au 52%, Pd 39%. Genesis Co 53%, Cr 27%. • Solder: Olympia Pre-solder Au 70%, Pd 10%, Ag 18%.

Dominici et al. J of Prostho 1995;4:2, 101-110. 100 Dr. Jose "Paco" Cortes-Botello


• 10 pair of specimens for each alloy and solder method. • Soldered and re-soldered with the other method.

• Torch Solder: 12 mm Length O2 flame at pressure of 34.5 MPa. • Infrared Soldering: Ney Infrared 1000 W Tungsten filament quartz lamp.

Dominici et al. J of Prostho 1995;4:2, 101-110.

14mm

6 mm

0.25 mm

3 mm


Results.

• Percentage of fracture and discolor for specimens.

• Tensile strength.

Dominici et al. J of Prostho 1995;4:2, 101-110.

Au-Pd Co-Cr Torch Infrared Torch Infrared

Cohesive Frac. 61% 79% 47% 18%

No Discolor 39% 11% 18% 18% Discolor 1/3 28% 68% 70% 82% Discolor 2/3 33% 21% 12% 0 Voids, porosity 89% 32% 82% 12%


Results. • Au-Pd Infrared “free defect”.

Au-Pd Torched “porosity”.

Cr-Co Torched “porosity”.

Cr-Co Torched “adhesive” and cohesive fracture.

Magnification 10X. 103 Dr. Jose "Paco" Cortes-Botello

Conclusions.

• There were no significant differences between bond strength of Au-Pd and Co-Cr alloys when both had infrared heated joints or torch heated joints.

• Entirely cohesive fractures were observed more frequently for Au-Pd

specimens. • Infrared solder joints, for both alloys, showed significantly less porosity,

voids and inclusions than torched heated joints, at 40 x magnification.

Dominici et al. J of Prostho 1995;4:2, 101-110. 104 Dr. Jose "Paco" Cortes-Botello

Solder between precious and nonprecious.

• Photomicrographic evaluation of solder joints between precious and nonprecious alloys.

• Solder joints between gold alloys and nonprecious metals. (Solder mr = 1370 ºF)

• A chemical and physical union between solder and gold alloy.

• Interface between the solder and nonprecious alloy lacked of chemical and physical union.

Walters. JPD 1976;35:689-692. 105 Dr. Jose "Paco" Cortes-Botello

Alloy and final color.


Spectrophotometric evaluation of alloys.

• Purpose: To evaluate the influence of 4 types of alloys and 2 porcelains on the final color.

• 2 Porcelains: Vita Omega and Dentsply Ceramco. • 10 specimens (10 x 1mm) per alloy:

• 2 opaque layers A3. (0.2mm) • 2 dentin layers A3. (1.0mm)

Kourtis et al. JPD 2004;92:5, 477-485.

Alloy Composition Thermabond Ni, Cr Wirobond Co, Cr Cerapal-2 Pd, Cu V-Delta Au, Pd.

Spectrophotometer: Datacolor Spectraflash 600


CIE Lab color system.

• Color difference ΔE > 3.7 visually unacceptable difference. • L* = lightness (value). • a* = red-green axis.

• b* = yellow-blue axis.

Kourtis et al. JPD 2004;92:5, 477-485. 108 Dr. Jose "Paco" Cortes-Botello

Results.

• Vita Porcelain showed highest L* values for all alloys. • Ceramco porcelain showed higher a* values. • Au-Pd and Co-Cr, higher L* with both porcelains. • Au-Pd with Vita porcelain showed higher b*.

Kourtis et al. JPD 2004;92:5, 477-485. 109 Dr. Jose "Paco" Cortes-Botello

Conclusions. • Type of alloy influenced the final color of the restorations.

• Vita porcelain showed the highest L* values for all alloys.

• Au-Pd and Co-Cr showed significant higher L* values. (brighter)

• For all the alloys tested, Ceramco Porcelain was found to be more red.

(higher a*)

• Au-Pd and Pd-Cu were founded to be more yellow (higher b*) with both porcelains.

Kourtis et al. JPD 2004;92:5, 477-485.


High Pd alloys effect on final color. • In vitro study to evaluate the final color difference of 9 high Pd alloys. • 6 disk specimens (16mm x 1mm) per alloy. • 2 groups:

– Opaque porcelain (0.1mm) – Opaque porcelain (0.1mm) + Dentin porcelain (0.9mm)

• Shade B1 Vita.

Stavridakis et al. JPD 2004;92:2, 170-8.

Alloy Composition

Spartan Plus Pd 79%, Ga, Cu

Liberty Pd 76%, Ga, Cu

Freedom Plus Pd 78%, Ga, Cu

Legacy Pd 85%, Ga

IS 85 Pd 82%, Ga

Protocol Pd 75%, Ga

Legacy XT Pd 75%, Ga

Jelenko No. 1 Pd 78%, Ga

Super Star Pd 60%, Ag

Olympia Au 52%, Pd 39%

CR 400 Chroma Meter, Konica. 111 Dr. Jose "Paco" Cortes-Botello

Results.


Acceptability intraorally = 2.8 – 3.7 ΔE CIELAB units. Acceptability ideal conditions = 1.0 ΔE CIELAB units.


Results.


darker greenish


Conclusions. • Pd-Cu-Ga alloys did not reliable reproduce the final color after firing cycle.

Darker, greener and less yellow. • Opaque porcelain. (2.8 – 3.7 ΔE CIELAB units) • Dentin porcelain. ( > 1 ΔE CIELAB units)

• Pd-Ag alloy, after firing cycle, showed Lighter, color differences after glaze cycle > 1 ΔE CIELAB units.

• Color differences for all other Pd-Ga alloys and Au-Pd were not significant < 1 ΔE CIELAB units.

Stavridakis et al. JPD 2004;92:2, 170-8. 114 Dr. Jose "Paco" Cortes-Botello

Titanium.


Marginal fit comparison Au and Ti alloys.

• Titanium:

• To compare the marginal fit, between implant frameworks made of Au and Ti alloys, before and after electroerosion.

• Special machines ($). • High fusion temperature. • Low detail reproducing capacity. • Difficult to manipulate.

Biocompatibility. Corrosion resistance. Physical properties. Low density. (weight) Low cost.

Sartori et al. JPD 2004;92:2,132-8. 116 Dr. Jose "Paco" Cortes-Botello

Materials and methods. • 3 unit FPD frameworks were fabricated (n=10).

Sartori et al. JPD 2004;92:2,132-8.

Au alloy. – Induction melting and

centrifugal, Neutrodyn. – Gold cylinders.

Ti alloy. – Electric arc melting, Argon atm. – Injection metal with vacuum pressure. – MR = 1668ºC. – Plastic cylinders.

Master Screw, Brazil.

3.75 mm

3 mm

10 mm



• 12 measures per implant: B, L, D, M. • Passive fit, 1 screw tightened.

– Tightened side. – Opposite side.

• Both screws were tightened to 10 N. • Electroerosion, Electric Discharge TMT.

Sartori et al. JPD 2004;92:2,132-8. 118 Dr. Jose "Paco" Cortes-Botello

Results.


Before Electroerosion After Electroerosion

Alloy. Opposite Tightened Both Opposite Tightened Both

Au 69 ± 25 12.8 ± 1.4 12.6 ± 3 35.7±8.2 8.3 ± 4.2 5.4 ± 2.3

Ti 94 ± 40 29.6 ± 4.4 30.1 ± 6 45.7±4.7 17 ± 5.3 16 ± 5.5

Au, opposite, before electroerosion. Au, opposite, after electroerosion.

Results in µm


Conclusions.

• Electroerosion procedure significantly reduced marginal gap for both alloys in all conditions.

• Comparison between both alloys after electroerosion did not show significantly differences for the opposite side.

• Au alloy showed the shortest marginal gaps in all conditions.


Alloy Opposite Tightened Both

Au before electroerosion 69 ± 25 12.8 ± 1.4 12.6 ± 3

Ti after electroerosion 45.7±4.7 17 ± 5.3 16 ± 5.5

Results in µm


Conclusions.

Criteria for alloy selection.

1. Know and understand alloy composition (allergies). 2. Single phase. 3. Avoid selection based on color. 4. Keep track of the alloys used, name and manufacturer. 5. Long-term clinical performance, and long term costs of restorations

over short term costs. 6. Clinical situations: esthetics, occlusion, space, curvature, length.


Conclusions.

Use reliable, clinically proven products. Companies research and manufacture alloys. Tested alloys for element release and corrosion. Dental laboratory.

As Prosthodontists, we are responsible for the safety and success or

failure of our restorations.


THANK YOU


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