Ceramic gold alloys seminar - American Prosthodontic Society

Transcripción

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
Dr. Jose "Paco" Cortes-Botello
1
Overview.
•
•
•
•
•
•
•
Introduction.
History.
Physical properties.
Chemical properties.
Classification.
Literature Review.
Summary.
2
Introduction.
3
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.
4
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.
5
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.
6
History.
7
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.
8
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
History.
• Au 1969 $35/oz, 1980 $800/oz, November 2005 $495/oz *
• Pd 1980 $150/oz, 2000 $1000/oz, November 2005 $267/oz *
$1,200
$1,000
$800
Au
$600
Pd
$400
$200
$0
1969
1980
2000
2005
*www.kitco.com
10
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
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.
12
13
•
N = kg (m/s²)
•
Pa = N/m² = kg (m/s²) / m²
•
Kg/mm²
– A newton is the amount of force required to accelerate a mass of one kilogram at a rate of
one meter per second squared.
– A pascal is the unit of pressure = one Newton per square metre.
– 1 megapascal (MPa) = 1 000 000 Pa = 1 N/mm²
– Unit of Vickers's Hardness.
14
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 (%)
Elongation
Yield strength
Wataha, JPD 2002;87:4, 351-363.
15
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
16
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
M-90 $58,000
* NEWAGE, INC.
* www.hardnesstesters.com
Dr. Jose "Paco" Cortes-BotelloWataha,
JPD 2002;87:4, 351-363.
17
Hardness.
•
•
Diamond is a transparent crystal of pure carbon consisting of tetrahedrally bonded
carbon atoms.
Aggregated diamond nanorods (Natalia Dubrovinskaia, at the University of
Bayreuth, Germany in 2005).
Carat
Cost per carat
Total cost US$
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
Unit cell of a diamond
1 carat = 200mg
18
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.
High noble alloy, etched (100x)
Grain size = 10µm
Wataha, JPD 2002;87:4, 351-363.
19
Phase structure or microstructure.
• Single Phase.
• Multiple Phase.
Homogeneous.
Elements soluble.
Au, Pd, Cu.
Less corrosion.
Easier to manipulate.
Heterogeneous.
Not completely soluble.
Au, Pt.
Higher corrosion.
Can be etched.
1000 x
Wataha, JPD 2002;87:4, 351-363.
20
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
Chemical Properties.
22
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.
23
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.
Wataha, JPD 2002;87:4, 351-363.
24
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.6
• If P CTE <<<< A CTE, MC bonding will fail as a result of compressive stress.
Wataha, JPD 2002;87:4, 351-363.
25
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.
Wataha, JPD 2002;87:4, 351-363.
26
Classification.
27
ADA Classification, 1984.
•
• Composition.
• Hardness
• Yield strength
• Elongation
• Amount of Au and noble
metals.
• Corrosion.
CLASS
Composition wt %.
ADA
Hardness
Clinical use
Yield
strength
Elongation
High Noble
Au >40%
Noble metal >60%
I
Soft
Inlay
<140 MPa
18%
II
Medium
Inlay, onlay
140 - 200
18%
Noble
Noble metal >25%
III
Hard
Full crown, short
FPD
201 - 340
12%
Base-metal
Noble metal < 25%
IV
Extra Hard
Long FPD RPD
framework
>340
10%
Wataha, JPD 2002;87:4, 351-363.
28
High noble.
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
• 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.
29
Noble.
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
•
•
•
•
Harder alloys.
Higher strength.
Thicker oxide layer.
Lower cost.
•
•
•
Multiple phase.
Higher corrosion, Cu, Ag.
Manipulation is difficult.
Wataha, JPD 2002;87:4, 351-363.
30
Base-metal alloys.
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
• 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.
31
Purpose
Disadvantages
Au
Nobility
Hardness
Pd
Nobility, Higher MR, Hardness
Oxide, grayness.
Ag
Increases solubility of elements (single phase) Thick oxide, greening.
Hardness
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
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.
33
Literature review.
34
Corrosion.
35
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.
36
Materials and methods.
•
•
•
•
Scanning Electronic Microscopy (SEM)
Element analysis
Immersion test
Cell culture test (mice fibroblasts)
32mm
10mm
1.5mm
x9
x9
{
a) *Preoxidize.
b) -0.1mm.
c) -0.2mm.
*preoxidize 1010ºC, 5min.
37
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
38
SEM and element analysis.
Option (Cu)
• As casting.
IS85
• No visible oxidation.
200 x
• After preoxidation.
26 x
b
200 x
4000 x
Syverud et al. Dental
Materials 2001;17:7-13.
39
Cytotoxicity.
40
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.
41
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
• 10 Disk specimens (1.2 x 0.13 cm), 2 groups:
• As cast.
• Heat treated, firing cycle
– Vita porcelain
Alloy
Liberty
Composition
Pd 76%, Cu, Ga
Freedom Plus Pd 78%, Cu, Ga
• 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.
Legacy
Pd 85%, Ga
Olympia
Au 52%, Pd 38.5%
Sun et al. JPD 2002;87:1, 86-93.
43
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.
Sun et al. JPD 2002;87:1, 86-93.
44
Results.
Sun et al. JPD 2002;87:1, 86-93.
45
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.
Sun et al. JPD 2002;87:1, 86-93.
46
Recasting alloys.
47
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
•
•
•
•
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.
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
49
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.
50
Element release in parts per billion.
Alloy
Ni
Remanium
Ni, Cr
New.
50% R
100% R
132
206
218
Wiron 99
Ni, Cr
New.
50% R
100% R
214
246
264
Wirobond C
Co, Cr
New.
50% R
100% R
CB Soft
New.
50% R
100% R
Ni, Cr, Cu
Thermobond
Cu, Al, Fe
New.
50% R
100% R
Cr
Co
Cu
Al
Fe
56
74
193
22
1520
6560
21
61
54
13
60
28
28
109
269
323
546
435
471
501
Mo
21
116
15
433
539
602
7457
10,650
17,848
51
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.
52
Marginal accuracy.
53
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.
Dr. Jose "Paco"Christensen.
Cortes-Botello
JPD 1966;16:2, 297-305.54
Wilhelm Conrad Roentgen, 1895.
First X-ray, 1896.
Michael Pu, 1896.
E. Haschek, 1896.
Dr. Jose "Paco"www.xray.hmc.psu.edu/rci/ss1/ss1_2.html
Cortes-Botello
55
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.
2.
3.
4.
Margins completely covered
Margins clinically acceptable, may need burnishing.
Questionable margins, may not be closed.
Clinically unacceptable.
56
Results.
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.
Nitkin and Asgar. JADA 1976;93, 622-629.
57
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
Semiprecious vs nonprecious alloys.
• In vitro study.
• Marginal accuracy
• Clinical 18 month follow up study.
•
•
•
•
Gingival Irritation
Tooth sensitivity
Tarnish and corrosion
Abrasion
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%
Landesman et al. JPD 1981;46:2, 161-166.
59
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.
Inlay
Crown
Die
Die
High Au alloy x 60
Pd-Ag alloy x 60
60
Clinical study.
• Evaluation at 3, 6, 12 and 18 months.
• Index range = 1 - 4
Alloy
Gingival
Irritation
Sensitivity
Abrasion
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
Corrosion
Tarnish
2
6
6
1
28%
85%
85%
14%
Table shows number of restorations and percentage free of defects.
Mixed
Rank
4
61
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.
62
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.
63
Results.
Hi Temp (immersed in 100ºF water)
Neoloy (bench cure)
100
100
90
90
80
80
70
70
60
Adequate
50
40
60
% 50
Adequate
Undersized.
40
Undersized.
Oversized
30
Oversized
30
20
20
10
0
10
A
0
A
B
C
D
E
B
C
D
E
F
Alloy
F
Ceramigold 2 (immersed in 100ºF water)
Base metal alloys A, B, C, D, E.
100
90
(Biobond, Ceramalloy II, Unibond,
Biocast, Neobond II)
80
70
60
Adequate
50
Undersized.
40
Oversized
30
High noble gold alloy F. (Olympia).
20
10
0
A
B
C
D
E
F
64
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.
65
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.
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%
Tjan et al. JPD 1991;66:157-164.
66
• 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.
4 layers of die spacer
Video microscope, Digimatic micrometers.
1 µm resolution.
Tjan et al. JPD 1991;66:157-164.
67
Results.
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.
140
120
100
80
µm
M.G.
60
V.D.
40
20
0
Au
Au, Pd
Pd
Cu
Ni, Cr
Ag
Alloy
Tjan et al. JPD 1991;66:157-164.
68
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
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
• 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.
Ayad, JPD 2002; 87:2,162-6.
71
• 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.
Ayad, JPD 2002; 87:2,162-6.
72
Results.
• Marginal discrepancy.
– Less 25 µm for all groups.
– Significant difference
between 3 groups.
• Composition analysis.
– Au decreased significantly in
recast metal.
– Pd increased.
Ayad, JPD 2002; 87:2,162-6.
73
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.
Ayad, JPD 2002; 87:2,162-6.
74
75
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
Alloy
Composition
Olympia
Au 52%, Pd 38%, In, Ga
JPW
Au 49%, Pd 31%, Ag 14%
Neydium
Au 49%, Pd 31%, Ag 14%
Instron Machine.
Strain Gauge Extensometer.
Vickers Metallograph.
Spectrophotometry.
76
Results.
Neydium
Property
JPW
Olympia
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
199
218
187
214
213
225
Hardness DPN
* Values x 1000 PSI
77
Results.
Neydium
Au 49%, Pd 31%, Ag 14%
JPW
Au 49%, Pd 31%, Ag 14%
Olympia
Au 52%, Pd 38%, In, Ga
78
Results.
Au 49%, Pd 31%, Ag 14%
A
Au 49%, Pd 31%, Ag 14%
B
Au 52%, Pd 38%, In, Ga
C
Heat treatment.
5 min at 1800 ºF
Magnification 450 X
79
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.
80
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
• 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)
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%
82
Results.
Vickers Hardness.
Alloy.
Manufacturer Information.
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
• Tested as cast and after firing
cycle:
•
•
•
•
1 oxidation.
1 opaque.
2 body.
1 glaze.
83
SEM Results.
• As Cast.
After Firing Cycle.
• Freedom
• Pd, Cu, Ga
• Legacy
• Pd , Ga, Ag
» Ru
84
SEM Results.
• As Cast.
After Firing Cycle.
• Accu-Star
• Pd, Ag, Ga
• Super-Star
• Pd, Ag
85
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.
86
Investments.
87
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
• 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.
89
Results.
52%
38%
25%
48%
•
1 die of each group was internally adjusted as a pilot study. All measurements
ranged between 15-30 µm.
90
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.
91
Temperature and distortion.
92
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
Material and methods.
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
94
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.
95
Results.
Marginal opening = d1 – d2.
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
ALLOY
Results in µm.
96
Results.
• Vertical gap in µm after complete heat treatment.
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
128*
84*
Superstar
38
87*
Olympia
24
52*
Jelenko No. 1
*values greater than the 40µm
97
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.
98
Solders.
99
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
• 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.
6 mm
3 mm
14mm
0.25 mm
101
Results.
• Percentage of fracture and
discolor for specimens.
Au-Pd
• Tensile strength.
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%
102
Results.
•
Au-Pd Infrared “free defect”.
Au-Pd Torched “porosity”.
Magnification 10X
.
Cr-Co Torched “porosity”.
Cr-Co Torched “adhesive” and cohesive
fracture.
103
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.
104
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
Alloy and final color.
106
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)
Alloy
Composition
Thermabond
Ni, Cr
Wirobond
Co, Cr
Cerapal-2
Pd, Cu
V-Delta
Au, Pd.
Spectrophotometer: Datacolor Spectraflash 600
Kourtis et al. JPD 2004;92:5, 477-485.
107
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
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
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.
110
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.
CR 400 Chroma Meter, Konica.
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%
Stavridakis et al. JPD 2004;92:2, 170-8.
111
Results.
Acceptability intraorally = 2.8 – 3.7 ΔE CIELAB units.
Acceptability ideal conditions = 1.0 ΔE CIELAB units.
112
Results.
greenish
darker
113
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.
114
Titanium.
115
Marginal fit comparison Au and Ti alloys.
• Titanium:
Biocompatibility.
Corrosion resistance.
Low density. (weight)
Low cost.
•
•
•
•
Special machines ($).
High fusion temperature.
Low detail reproducing capacity.
Difficult to manipulate.
• To compare the marginal fit, between implant frameworks made of Au
and Ti alloys, before and after electroerosion.
Sartori et al. JPD 2004;92:2,132-8.
116
• 3 unit FPD frameworks were fabricated (n=10).
Ti alloy.
Au alloy.
– Induction melting and
centrifugal, Neutrodyn.
– Gold cylinders.
–
–
–
–
Electric arc melting, Argon atm.
Injection metal with vacuum pressure.
MR = 1668ºC.
Plastic cylinders.
3 mm
3.75 mm
10 mm
Master Screw, Brazil.
117
• 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.
118
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
Results in µm
Au, opposite, before electroerosion.
Au, opposite, after electroerosion.
119
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.
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
Alloy
Results in µm
120
Conclusions.
Criteria for alloy selection.
1.
2.
3.
4.
5.
6.
Know and understand alloy composition (allergies).
Single phase.
Avoid selection based on color.
Keep track of the alloys used, name and manufacturer.
Long-term clinical performance, and long term costs of restorations
over short term costs.
Clinical situations: esthetics, occlusion, space, curvature, length.
121
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.
122
THANK YOU
123

Ceramic gold alloys seminar - American Prosthodontic Society

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