6. INTRODUCTION
• Dental amalgam is a metal like restorative
material composed of a mixture of silver-tin-
copper alloy and mercury.
• Amalgam has been the primary restorative
material for around 150 years.
• ORIGIN OF AMALGAM can be traced back to
659 AD in CHINA.
• FATHER OF AMALGAM-REGNART
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7. Why Amalgam?
• Inexpensive
• Ease of use
• Proven track record
– >150 years
• Familiarity
• Resin-free
– less allergies than composite
8-Jun-16 7
8. DEFINITION
• Amalgam technically means an alloy of
mercury with any other metal.
• Dental amalgam is an alloy made by
mixing mercury with a silver-tin dental
amalgam alloy.
8-Jun-16 8
9. TERMINOLOGY DEFINITION
Amalgam Amalgam is an alloy which has mercury as
one of its components
– Marzouk (1997)
Dental Amalgam An alloy of mercury, silver, copper, tin,
which may also contain palladium, zinc,
and other elements to improve handling
characteristics and clinical performance
– Anusavice (2003)
Dental Amalgam
Alloy /
Alloy for Dental
Amalgam
An alloy of silver, copper, tin, and other
elements that is formulated and processed
in the form of powder particles or as a
compressed pellet
– Anusavice (2003)
8-Jun-16 9
10. TERMINOLOGY DEFINITION
Amalgamation The process of mixing liquid mercury with
one or more metals or alloys to form an
amalgam. – Anusavice (2003)
Trituration The process of grinding powder, especially
within a liquid. In dentistry, the term is used
to describe the process of mixing the
amalgam alloy particles with mercury in an
amalgamator. – Anusavice (2003)
8-Jun-16 10
12. YEAR EVENTS
1819 First dental silver amalgam is supposed to
have been introduced into England by Bell –
“Bell’s Putty”
1833 Introduced to the North American continent by
Cawcour brothers termed as “Royal Mineral
Succedaneum”.
1843 Resolution passed by the American Society
of Dental Surgeons (the first organised Dental
Society in the U.S.A declaring the use of
amalgam a “Malpractice”.
Thus the Amalgam War began
1845 “Amalgam Pledge” was adopted by the
society.8-Jun-16 12
13. YEAR EVENTS
1850 Pledge was rescinded officially ending the
amalgam war.
1861 First research programme was conducted by
John Tomes ( Trans.Odontol.Soc. G.B.,Vol III)
Who measured shrinkage of a number of
amalgams
1871 Charles Tomes measured shrinkage &
expansions by specific gravity tests.
1874 Thomas B.Hitchcock (Trans.N.Y.Odontol.Soc)
did some important work in measuring more
accurately by means of a micrometer
changes of amalgam form8-Jun-16 13
14. True amalgam science began with the
investigations by G.V.Black during 1890,s.
1895
G.V. Black
developed formula
for modern amalgam
alloy
• 67% silver, 27% tin,
5% copper, 1% zinc
overcame expansion
problems
8-Jun-16 14
15. YEAR EVENTS
1896 Classic work of G.V.Black that a more
systematic study was made of the properties
& manner of manipulation of silver amalgam
and its relation to cavity preparation.
Many of G.V.Black’s techniques for
amalgam restorations are generally accepted
today.
New methods are often described as
variations or modifications of those used by
Black.
8-Jun-16 15
16. YEAR EVENTS
1930 A.D.A research organisation conducted a
survey and showed that only a few of the
proprietary amalgam alloys on the market &
tested by the National Bureau of Standards
were reliable.
A.D.A specification No. 1 for Alloy.
A.D.A specification No. 6 for Mercury.
1934 &
1960
Revision of this specification
8-Jun-16 16
17. YEAR EVENTS
1970 Inclusion of a diametral tensile strength as
an indication of the rate of hardening of the
amalgam as distinct from a compressive
strength test.
Adjustments in the setting change & flow
requirements that are due to changes in test
procedures.
Change from hand trituration to mechanical
trituration
1957 &
1961
British Standards Institution provided a
specification number currently under review
8-Jun-16 17
18. CONSTITUENTS IN AMALGAM
• Basic
– Silver
– Tin
– Copper
– Mercury
• Other
– Zinc
– Indium
– Palladium
8-Jun-16 18
20. Basic Constituents
• Copper (Cu)
– ties up tin
• reducing gamma-2
formation
– increases strength
– reduces tarnish and
corrosion
– reduces creep
• reduces marginal
deterioration
Phillip’s Science of Dental Materials 2003
8-Jun-16 20
21. Basic Constituents
• Mercury (Hg)
– activates reaction
– only pure metal that is liquid
at room temperature
– spherical alloys
• require less mercury
– smaller surface area easier to wet
» 40 to 45% Hg
– admixed alloys
• require more mercury
– lathe-cut particles more difficult to wet
» 45 to 50% Hg
Phillip’s Science of Dental Materials 2003
8-Jun-16 21
22. Other Constituents
• Zinc (Zn)
– used in manufacturing
• decreases oxidation of other elements
– sacrificial anode
– provides better clinical performance
• less marginal breakdown
– causes delayed expansion with low Cu alloys
• if contaminated with moisture during condensation
Phillip’s Science of Dental Materials 2003
H2O + Zn ZnO + H2
8-Jun-16 22
23. Other Constituents
• Indium (In)
– decreases surface tension
• reduces amount of mercury necessary
• reduces emitted mercury vapor
– reduces creep and marginal breakdown
– increases strength
– must be used in admixed alloys
– example
• Indisperse (Indisperse Distributing Company)
– 5% indium
8-Jun-16 23
26. ACC. TO STURDEVANT’s
1) BASED ON COPER CONTENT
CONVENTIONAL OR LOW COPPER ALLOY
HIGH COPPER ALLOY
HIGH COPPER ADMIXED ALLOY
HIGH COPPER UNICOMPOSITIONAL ALLOY
2) BASED ON AMALGAM ALLOY PARTICLE GEOMETRY &
SIZE
1) LATHE CUT ALLOY
-REGULAR-CUT
-FINE-CUT
-MICROFINE-CUT
2) SPHERICAL ALLOY
3)ADMIXED ALLOY
8-Jun-16 26
27. 3) ACCORDING TO ZINC CONTENT
1)ZINC CONTAINING ALLOYS
2)ZINC FREE ALLOYS
4)NEW AMALGAM ALLOYS
8-Jun-16 27
28. CLASSIFICATION
(MARZOUK)
1) ACCORDING TO NO. OF ALLOY METALS
I. BINARY ALLOYS(SILVER-TIN)
II. TERNARY ALLOYS(SILVER-TIN-COPPER)
III. QUATERNARY ALLOYS(SILVER-TIN-
COPPER-INDIUM)
2) ACCORDING TO THE SHAPE OF
POWDER PARTICLES
SPHERICAL
LATHE CUT
ADMIXED
8-Jun-16 28
29. Particle Shape
• Lathe cut
– low Cu
• New True
Dentalloy
– high Cu
• ANA 2000
• Admixture
– high Cu
• Dispersalloy, Valiant
PhD
• Spherical
– low Cu
• Cavex SF
– high Cu
• Tytin, Valiant
8-Jun-16 29
34. • Acc. To ADA specification no. 1 requires
that the amalgam alloys contain
predominantly silver and tin.
• Unspecified amounts of other elements
like copper, zinc, gold and mercury are
allowed in concentrations less than the
silver or tin content.
8-Jun-16 34
35. LOW COPPER ALLOYS
ACCORDING TO STURDEVANT AND ANUSAVICE-
SILVER 65%- 70%
TIN 25%-30%
COPPER 4%-5%
ZINC 1%
ACCORDING TO COMBE-
SILVER 65-74%
TIN 25-27%
COPPER 0-6%
ZINC 0-2%
8-Jun-16 35
36. HIGH COPPER AMALGAM ALLOY-
1.ADMIXED ALLOY
POWDER
ACCORDING TO
STURDEVANT-
SILVER 60%
TIN 27%
COPPER 13%
ZINC 0%
ACCORDING TO COMBE-
SILVER 69%
TIN 17%
COPPER 13%
ZINC 1%
2.SINGLE COMPOSITION
ALLOY-
SILVER 60%
TIN 25%
COPPER 15%
8-Jun-16 36
38. Method of Adding Copper
• Single Composition Lathe-Cut (SCL)
• Single Composition Spherical (SCS)
• Admixture: Lathe-cut + Spherical Eutectic (ALE)
• Admixture: Lathe-cut + Single Composition
Spherical (ALSCS)
8-Jun-16 38
39. • Also available these days are; PRE
AMALGAMATED ALLOYS
• In this the surface of alloy particles have
been introduced to mercury by
manufacturer.
Contain upto 35% Hg.
8-Jun-16 39
45. NUMBER OF ATOMSSTOICHIOMETRI
C FORMULA
PHASES
Ag-CuSilver-
Copper
Eutectic
Cu6Sn5
Copper-Tin
phase
(Eta)
Cu3Sn
Copper-Tin
phase
(Epsilon)
8-Jun-16 45
46. SCHEMATICs OF SETTING
Rxn
• Before Rxn; Alloy
Particles are
dispersed in Mercury
• After Rxn; Residual
alloy particles are
embeded in a matrix of
Crystalline reaction
products
8-Jun-16 46
47. Basic Composition
• A silver-mercury matrix containing filler
particles of silver-tin
• Filler (bricks):
– Ag3Sn called gamma
• can be in various shapes
– irregular (lathe-cut), spherical,
or a combination
• Matrix:
– Ag2Hg3 called gamma 1
• cement
– Sn8Hg called gamma 2
• voids
Phillip’s Science of Dental Materials 2003
8-Jun-16 47
55. Compressive Strength:
High Copper amalgam > low copper amalgam
Tensile Strength: Its is important for Fracture
Resistance ; High Copper amalgam< low copper
amalgam
FACTORS AFFECTING STRENGTH
TRITURATION
MERCURY CONTENT
EFFECT OF CONDENSATION
EFFECT OF POROSITY
EFFECT OF AMALGAM HARDENING RATE
8-Jun-16 55
56. DIMENSIONAL CHANGES-
When mercury is combined with amalgam it
undergoes three distinct dimensional changes
STAGE 1-INITIAL CONTRACTION
Lasts for about 20 mins
Contraction which occurs is not > 4.5µm/cm
STAGE 2-EXPANSION
STAGE 3-LIMITED DELAYED CONTRACTION
EXPANSION IS MORE FOR LOW COPPER THAN
HIGH COPPER ALLOYS.8-Jun-16 56
57. FACTORS THAT AFFECT THE
DIMENSIONAL CHANGES-
1.Particle size & shape
2.Mercury
3.Manipulation
4.Moisture contamination- this type of
expansion can reach values greater
than 400µm.
8-Jun-16 57
59. FLOW AND CREEP
WHEN A METAL IS PLACED UNDER STRESS,IT
WILL UNDERGO PLASTIC DEFORMATION.THIS
CHARACTERISTIC IS REFERRED AS FLOW OR
CREEP.
FLOW IS MEASURED DURING SETTING OF
AMALGAM
CREEP IS MEASURED AFTER AMALGAM SETTING.
- IT IS DEFINED AS INCREMENTAL
DEFORMATION.
- VARY FROM 0.1% TO 4%
8-Jun-16 59
60. HIGH COPPER ALLOYS HAVE LOWER CREEP
VALUES THAN CONVENTIONAL LOW
COPPER ALLOYS.
FACTORS INFLUENCING CREEP
1.Phases of amalgam restorations
2.Manipulation
8-Jun-16 60
62. TARNISH AND CORROSION-
TARNISH:Is a surface discolouration on a
metal or even a slight loss or alteration of
the surface finish or luster.
CORROSION:It is the destructive attack of a
metal by chemical or electrochemical
reaction with its environment.
8-Jun-16 62
63. TYPES OF CORROSION-
1.Chemical corrosion
2. Electrochemical corrosion
a)Galvanic corrosion
b)Crevice corrosion
C) Stress corrosion
8-Jun-16 63
64. Other Physical Properties
1. Thermal conductivity =
2. Electrical conductivity =
3. Coefficient of thermal expansion =
4. Radiopacity =
5. Color =
[>2 mm Aluminum]
[Lustrous, shiny, white]
25 ppm/ºC
[High]
[High]
66. Biological Properties
Mercury Toxicity:Transient : intraoral release (<35 mg/m3)
Mercury Hypersensitivity:Low level allergic reaction
Estimated to be < 1 / 100,000,000
Amalgam Tatoo:
Can occur during amalgam removal if no rubber dam
Embedded amalgam particles corrode and locally discolor gum
No known adverse reactions
67. FACTORS AFFECTING THE
QUALITY OF AMALGAM
1) Factors governed by the dentist:
a) Selection of an alloy.
b) Mercury alloy ratio.
c) Trituration process.
d) Condensation technique.
e) Marginal integrity.
f) Anatomical characteristics.
g) Final finish.
68. 2) Factors governed by the manufacturer :
a) Composition of the alloy.
b) Heat treatment of the alloy.
c) Size, shape and method of production
of the alloy particles.
d) Surface treatment of the alloy particles.
e) The form in which the alloy is supplied.
69. INDICATIONS
1. Moderate to large class I and class II
restorations.
2. Temporary caries control restorations for those
teeth that are badly broken down and require
subsequent evaluation of pulpal health before
definitive restoration.
3. Foundations for badly broken down teeth that
will require increased retention and resistance
form in anticipation of the subsequent placement
of a crown or a metallic onlay.
70. CONTRAINDICATIONS
1. Class III and class V restorations in
aesthetically critical areas.
2. Small to moderate restorations in
posterior teeth.
3. In Patients who are allergic to the alloy
components.
71. ADVANTAGES
1. Ease of use.
2. High compressive strength.
3. Excellent wear resistance.
4. Favorable long term clinical results.
5. Low cost than fot composites
75. Handling Characteristics
• Spherical
– advantages
• easier to condense
– around pins
• hardens rapidly
• smoother polish
– disadvantages
• difficult to achieve tight contacts
• higher tendency for overhangs
Phillip’s Science of Dental Materials 2003
76. Handling Characteristics
• Admixed
– advantages
• easy to achieve tight contacts
• good polish
– disadvantages
• hardens slowly
– lower early strength
77. Overview of Manipulation
Selection / Proportioning / Amalgamation / Manipulation / Polishing
Placement and
Condensation
Carving Burnishing Polishing
Onset of
MIXING
Onset of
WORKING
Onset of
SETTING
End of
SETTING
24 hours
TIME
80. Trituration
• Mixing time
– refer to manufacturer
recommendations
• Overtrituration
– “hot” mix
• sticks to capsule
– decreases working / setting time
– slight increase in setting contraction
• Undertrituration
– grainy, crumbly mix
Phillip’s Science of Dental Materials 2003
81. Mulling-It is actually a continuation of
trituration.
o Improves homogenicity of the mass and
texture.
o Done for 2-5 sec.
Consistency of mix-
Normal mix Undertriturated
grainy mix
83. Condensation
• Forces
– lathe-cut alloys
• small condensers
• high force
– spherical alloys
• large condensers
• less sensitive to amount of force
• vertical / lateral with vibratory motion
– admixture alloys
• intermediate handling between lathe-cut and spherical
84. CONDENSATION PRESSURE
• Forces as high as 66.7N are
recommended.
• Average forces exerted by the
practitioners range between 13.3 to 17.8N.
• To ensure maximum density and
adaptation to the cavity walls, the
condensation forces should be as great as
the alloy will allow, consistent with the
patient comfort.
8-Jun-16 84
85. Carving-It is the anatomical sculpturing
of the amalgam material.
o A scraping or ringing sound should be
heard while carving.
90. 6) Incorrect proximal contacts
7) Recurrent caries
8)Amalgam blues
9) Voids
10) Poor occlusal contacts
11) Bulk fracture of the tooth or
amalgam
91. CAUSES OF FAILURE
1) IMPROPER CASE SELECTION
2) IMPROPER CAVITY PREPARATION-
a) Inadequate extensions /Overextended cavity
preparation
b) Shallow cavity /Deep cavity preparation
c) Curve pulpal floor
d) Wide isthmus /Narrow isthmus
e) Sharp axiopulpal line angle
f) Lack of butt joint
g) Lack of occlusal convergence
h) Improper convenience form
92. 3) FAULTY SELECTION AND MANIPULATION OF
AMALGAM-
a) Selection of the alloy and mercury
b) Improper trituration
c) Improper condensation
d) Contamination
e) Over & under carving
f) Improper finishing
4) ERRORS IN MATRICING PROCEDURES AND
RESTORATION-
a) Unstable matrix
b) Poor contour
c) Absence of wedges
d) Premature matrix removal
8-Jun-16
92
94. Hg Facts & Uses
• Quick silver
• 13.6 times the weight of water
• Evaporates at room temperature
• Amalgam
• Many Industrial uses
95. MERCURY TOXICITY
Hg (Vapor)= odorless, colorless gas
Hg (Liquid)= penetrating liquid
Vapor Limits (TLV) =
0.05 mg/m3 = 50 mg/m3 = 5 ppb
Vapor Toxicity Calculations:
Sensitivity Calculations:
ADA 1 / 100,000,000
UNC 1 / 180,000,000
Occupational safety & health administration has set a
Threshold Limit Value(TLV) of 0.01mg/cu.mm as
maximum amount of mercury in the work place.
Lowest level of total blood mercury at which earliest non
specific symptoms occur is 35ng/ml
96. SOURCES OF MERCURY EXPOSURE IN
DENTAL OFFICE-
1) Amalgam raw materials
2) Mixed but unset amalgam
3) Dental amalgam scrap
4) During finishing and polishing
of amalgam.
5) During removal of old amalgam
restorations
97. MEASURES TO REDUCE MERCURY
EXPOSURE IN THE DENTAL CLINIC-
1. Storage of mercury
2. Care During trituration of amalgam
3. Care During insertion of amalgam
4. Disposal of amalgam scrap
5. During polishing of amalgam
6. During removal of old amalgam restorations
7. Care of contaminated instruments
8. Check mercury vapour levels periodically
9. Awareness of mercury toxicity
98.
99. ALLERGY
• Allergic responses are marked by itching,
rashes, sneezing, difficulty in breathing,
swelling or other symptoms like contact
dermatitis.
• These reactions are experienced by less than
1 % of the treated population.
• When such a reaction has been documented
by a dermatologist or an allergist, an
alternative material must be used unless the
reaction is self limiting.
101. NEWER TRENDS
• Because of a concern about the possible toxicity of
mercury in amalgams, a number of materials have
been developed.
1)Mercury-free direct –filling alloy:
– ADA-NIST (National Institute on Standards and
Technology) Patented this alloy
– Silver coated Silver-Tin particles that can be self-welded
by compaction (hand-consolidated)
2)Transitional approaches/Low Mercury Amalgams:
– Redesigning amalgam to have much less initial mercury
– Alloy particles pack together well
– Reduce mercury for mixing to the 15%-25% range
102. • PRIMM - Poly Rigid Inorganic Matrix Material -
Porous Ceramic fibers. Condensable, curable,
carvable, polishable. "White amalgam" .
3) GALLIUM BASED ALLOYS-
• First suggested by Puttkamer in 1928.
• Satisfactory gallium restorations were
developed by Smith & Others in 1956.
• Small amounts of indium &/or tin added to
gallium produces liquid alloy at room
temperature.
8-Jun-16 102
103. • Gallium melts at 28 degree Celsius and can be
used to produce liquid alloys at room
temperature by the addition of small amounts of
other elements such as indium.
• Gallium alloys are made with silver tin particles
in gallium- indium.
– PROPERTIES:
• Wettability
• Sets in reasonable time and possesses strength
• Diametrical stability & corrosion resistance equal to
or greater than silver amalgam
8-Jun-16 103
Restoration done with gallium alloys-
105. Advantages-
1. Compressive strength
similar to high copper
amalgams.
2. Biocompatibility
3. Good adaptation &
reduced marginal
leakage.
4. Low vapour pressure
than mercury
5. Creep values as low as
0.09%
6. sets early
Disadvantages-
1. Poor corrosion
resistance-
Corrosion poducts-
Ga2O3 & SnO2
2. Post operative sensitivity
3. Whitening of margins of
restoration-
Due to crystallization of
gallium oxy hydroxide
GaO(OH)
4. Stickiness
5. High cost
105
107. Studies of biocompatibility & cytotoxicity by
Eakle et al in 1992 & Psarras et al in 1992
have shown it is not significantly different
from amalgams and composite resins.
108. 4) INDIUM IN MERCURY-
10-15% Indium in admixed alloys reduces
the mercury needed for mixing.
Powell et al in 1989 first reported that the
addition of pure indium powder to a high
copper amalgam alloy decreases mercury
vaporization.
This type of amalgam is currently marketed
by INDISPERSE(Indisperse Inc,Canada)
8-Jun-16 108
109. 5) BONDED AMALGAM RESTORATIONS:
– Silver does not adhere properly to cavity walls
– Adhesive systems designed to bond amalgam to
enamel & dentin
– Improve adhesion, strengthen remaining tooth
structure, decreases the need for removal of
health tooth structure
– Pioneers were Sun Medical (Superbond),
Kurrary (Panavia)
– Superbond was based on 4-META/MMA resins
– Panavia was based on Bis GMAphosphonated
ester
110. • Later dentin bonding agents have also
been a subject of bonding amalgam to
dentin
• Various Agents are
– Amalgam Bond with HPA ( Parkell)
– All Bond 2 (Bisco)
– Optibond 2 (Kerr)
– Panavia 21(Kuraray)
– Clearfil Linear Bond 2 (Kuraray)
– Scothbond MP (3M)
111. • INDICATIONS:
– Auxillary retention
– Extensively carious posterior teeth
– Teeth with low Gingival-Occlusal height
– Temporary restorations
– Amalgam Sealants
• ADVANTAGE:
– More conservative
– Reinforces tooth structure
– Eliminates the use of pins
– Decreases the incidence of marginal fracture
– Provides a bond at the tooth restoration interface
112. – Biologic sealing of the pulpo-dentinal complex
– Appointment time
– Cost effective
• DISADVANTAGE:
– Technique sensitive
– Time to adapt to the new technique
– Clinical performance are not documented
– No sustained effects of amalgam bonding
when subjected to thermocycling
– Hydrolytic stability of the bond is questionable
114. • "...amalgam bonding is an adjunct to and
not a substitute for mechanical retentive
form. The main advantage of conventional
amalgam adhesives seems to be their
ability to seal the tooth restorative
interface, preventing microleakage into the
dental tubules and pulp and reducing post-
operative sensitivity.
- Cobb, et al, Am J Dent, Oct 1999
8-Jun-16 114
115. 6) FLUORIDATED AMALGAM-
Stannous Fluoride is added
Exact mechanism of fluoride uptake is not
known.
In vitro studies have shown reduction in
mechanical properties.
8-Jun-16 115
116.
117.
118. CONCLUSION
• Amalgam is a very good restorative material.
• While there are some concerns about its
use, it is a safe and effective direct
restorative material.
• A successful amalgam restoration is still
relatively easy to accomplish, and adherence
to tooth preparation and material handling
requirements will still result in a successful
restoration.
