DENTAL AMALGAM/prosthodontic courses

DENTAL AMALGAM
www.indiandentalacademy.com
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education

Contents
• Introduction
• History
• Classification
• Generations
• Types
• Amalgamation
• Advantages &disadvantages
• Setting reactions
• Properties
• Manipulation
• Condensation & mulling
• Mercury toxicity
• Failures
• Bonded amalgam
• Amalgam waste management
• Recent advances
• Conclusion

INTRODUCTION
Amalgam” derived from Greek word
“Emolient” which means paste.
Amalgam is an alloy of 2 or more metals
in which one of the constituents is essentially
Hg.
Dental amalgam is an alloy of Hg, Ag, Cu
& Sn which may contain Zn, Pd & other
elements to improve handling characteristics &
clinical performance. (Kenneth. J. Anusavice)

Indian Dental academy
• www.indiandentalacademy.com
• Leader continuing dental education
• Offer both online and offline dental courses

History of Dental Amalgam
-1819 - first dental amalgam introduced by Bell of
England and known as Bells putty and later used by
Taveau in Paris in 1826.
-1833 - Craw Cour brothers claimed a new material for
filling teeth in USA.
- A crude amalgam named Royal mineral succedaneum
was prepared from shavings of silver cut from coins
and mixed with enough mercury to make sloppy paste.

-1841 - Amalgam war initiated - there was very strong
opposition to the use of amalgam by the better
practitioners, which finally resulted in a crusade against its
use.
-Dr. Chapin Harris reported many cases of systemic effects
and even death resulting from the presence of mercury in
the amalgam
- Other claims that use of amalgam produced depression,
nervousness, indigestion, ptyalism, paralysis and death.
- 1843 - a resolution was passed by the American society
of dental surgeons declaring the use of amalgam as
malpractice.

-1845 – amalgam pledge adopted by this organization not
to use amalgam.
-1861 – first research program in amalgam was conducted
by John Tomes
-1871 – Charles Tomes measured shrinkage and expansion
by specific gravity tests.
-1896 G.V Black presented his classic work of systematic
cavity preparation and appropriate manipulation of
amalgam.

-Blacks amalgam was mixture of 72.5% silver and 27.5%
tin amalgamated with mercury. This formula significantly
improved dimensional stability of amalgam.
-In early 1900’s ‘copper amalgam’ was used and attempts
were made to increase strength of amalgams by increasing
copper content of the traditional amalgam alloy.
-1920 second amalgam war
-1959 Eame’s introduced minimal mercury technique with
reduced mercury alloy ratios.
- 1986 led to development of high copper amalgams with
composition Ag – 41 – 70%, Sn 15-30% Cu-12-28%.

CLASSIFICATION OF DENTAL AMALGAMS
I. According to number of alloyed metals
(a) Binary alloys (Eg:-Ag-Sn)
(b) Ternary alloys (Eg:- Ag-Sn-Cu)
(c) quaternary alloys (eg:- Ag-Sn-Cu, indium).
II. According to the shape of the powdered particles:-
Spherical (smooth surfaced spheres)
Lathecut (irregular shapes ranging)
Spheroidal (Spherical with irregular surfaces)

III. According to powder’s particles size
Microcut
Finecut
Coarse cut
IV According to the copper content of the powder:-
Low Cu – 6% or less
High Cu – 12% Cu
V. According to zinc content
1. Zinc containing amalgam > 0.01vol%
2. Zinc free alloys <0.01vol%

VI.
Ist
generation amalgam: studied recommended by G.V.
Black popular for more than 80 yrs. It consists basic
3 part Ag, 1 part Sn.
II nd
generation amalgam : Addition of Cu & Zn gave rise
to newer II generation. Cu - ↓ plasticity,↑ hardness
strength of alloy, Zn – dexodizer, ↓ brittle ness.
IIIrd
generation amalgam :- The admixture of spherical
Ag3
Cu eutectic alloy to original alloy powder creates a
valuable final product. This Ag – eutectic containing alloy
may be classified as III gen. Amalgam.

IV Generation amalgam :- The alloying of Cu to Ag and
Sn in 14 to 28% forms a ternary alloy in which most of Sn
is firmly bounded to Cu.
V Generation amalgam:- Alloying of Ag, Cu, Sn & In
together, creating true quaternary alloy in which almost of
Sn is available to react with Hg when mixed with powder.
VI Generation amalgam:- Alloying of Pd (10%), Ag
(62%), (Cu 28%), to form a eutectic alloy which is lathe
cut is blended into I, II or III generation amalgam in ratio
of 1:2, the set amalgam exhibits highest nobility of any
previous amalgam.

Low Cu alloy High Cu alloy
Admixed Single composition
Ag-65% 65-70% 60%
Sn-29% 17% 27%
Cu-2-5% 9-20% 13-30%
Zn-0.2% 1-2% 0-2%
COMPOSITION

Metallurgical phases and properties
The setting reactions of alloys for dental amalgam
with Hg are usually described metallurgical phases
involved. They do
γ- Ag3 Sn γ1
- Ag2
H3
γ2 –
Sn8
Hg
(Epsilon) – Cu3
Sn
η - (eta phase) Cu6
Sn5
Ag-Cu-eutectic
- Ag3
Sn phase is the strongest phase and should occupy
maximum available space in volume of restoration
- Sn-Hg phase lacks corrosion resistance and is weakest
components of dental amalgam.
- Amalgams of Sn rich alloys display less expansion thanwww.indiandentalacademy.com

-Ag-Sn alloys are brittle and difficult to comminute
uniformly unless a small amount of Cu is substituted for
Ag.
-An increase in cu content hardens and strengthens the Ag-
Sn alloy.
-The use of zinc in an amalgam alloy is a controversy. 1st
alloys with out Zn are more - brittle and their amalgams
tend to be less plastic during condensation carving
- The function of Zn in amalgam is a deoxidizer. Acts as a
scavenger during melting, uniting with oxygen to
minimize formation of other oxides.
- www.indiandentalacademy.com

It has some beneficial effects of early corrosion and
marginal integrity.
- Zn even in small amounts without proper isolation
causes abnormal expansion of amalgam over time due
to incorporation of H2
O into amalgam during
condensation or trituration.
- Small amounts of In or Pd have been included in
some commercial systems.

Metallurgical Properties
Silver:-
- It Unites with Hg in definite atomic proportions.
- It tarnishes from action of sulphides in mouth.
- It expands.
- It retards setting of mass
- Increases edge strength.
- Decreases flow
- Amalgamates slowly and with difficulty.

Tin:-
- It unites readily with Hg.
- It retards setting
- Increases flow
- Imports plasticity to mass.
- It shrinks.
- Decreases edge strength.
- Tarnishes readily from action of sulfides in mouth

Copper :-
- Increases strength
- Hastens setting
- Shows not appreciable expansion or contraction.
- Lessens flow.
Zinc :-
- Unites easily with Hg in definite atomic proportions
- It expands
- Improves the color of mass
- It imparts plasticity
- Diminishes edge strength.
- Increases flow
Mercury :-
Hg is liquid at room temperature its freezing
point is - 39°C.

MANUFACTURE OF AMALGAM
Lathe cut powder:
Done by grinding the ingot of alloy
by placing in a milling machine. The
filings are irregular in shape. It is
available as regular cut, fine cut and
microfine cut versions.

Homogenizing anneal
• Rapid cooling in got - cores structure contains
non homogenous grains.
• Homogenizing heat treatment - reestablishing
equilibrium phase relationship.
• Ingot –oven- heated at a temp below solidus.
• Time of heat treatment varies but 24 hrs at
selected temp is not unusual.

Spherical powder:
Done by melting together the desired elements.
Liquid metal is atomized into fine spherical droplets of
metal
- The powder produced is heat treated (Annealed) to
relieve the stress induced.
- Each particle has regular spherical shape.
- The average particle size of modern powder ranges
between 15 – 35 µm.

LATHE CUT ALLOYS SPHERICAL ALLOYS
 Alloy particles have
irregular shapes ranging from
spindles to shavings.
 Manufactured by milling
or lathe cutting a cast ingot of
an amalgam alloy.
 Requires more Hg for
mixing & have poor
properties.
 Mix is less plastic requires
heavy condensation pressure.
 Spherical smooth surface
 Manufactured by a process
called atomization
 Requires less Hg & have
better properties.
 Mix is more plastic and is
not sensitive condensation
pressures.

CLINICAL SIGNIFICANCE OF PARTICLE SIZE:
1. During carving, larger particles may be pulled out of
the matrix producing a rough surface, which is susceptible
to corrosion.
2. Amalgam made from lathe cut powders of admixed
powders tend to resist condensation better than amalgam
made entirely of spherical powders.

3. Spherical powder are extremely plastic and
require less Hg than lathe cut alloys. Because
spherical alloys have a smaller surface area per
volume than do the lathe cut alloys. Thus, the set
amalgam has low Hg content and better physical
properties.

TYPES OF AMALGAM RESTORATIONS
Low Cu amalgams:- These were prominent before early
1960s because of γ2
phase formed, the material was subject to
corrosion. This led to the development of high Cu amalgam.
High Cu amalgams :- It Cu content is 12% to 30%
designates as high Cu amalgams.
The adv. is that Cu reacts with Sn and inhibit the
formation of more corrosive (γ2
) phase within the amalgam
mass. This reduction of corrosion products reduces the
formation of a corrosion layer at amalgam tooth interface.
They are of 2 types spherical amalgam admixed and single
composition alloys. Advantage of spherical amalgam is high
early strength suited for very large amalgam restorations like
complex restorations.www.indiandentalacademy.com

ADMIXED HIGH Cu AMALGAM
SINGLE COMPOSITION HIGH
Cu AMALGAM
 3rd
generation alloy powder
particles contain 1 part of spherical
Ag – Cu eutectic alloy to 2 parts of
lathe cut low copper amalgam alloys
 Cu : 9-20%
 Contains high residual Hg content.
 Working time is longer and sets
slow
 Requires high condensation
pressures

Less early strength
 Creep is higher due to high residual
Hg content.
 Difficult to finish.
 4th
generation ternary alloy in which
copper is added up to 29% and Ag –
Cu is firmly bound to tin.
 Cu : 13-30%
 Low residual Hg content.
 Working time is less and sets faster.
 Requires low condensation
pressure.
 High early strength.
 Creep is low due to low residual Hg
content.
 Easy to finish.

Uses of Amalgam
1. Class I,II, & V restorations
2. Replacing lost walls.
3. As a retrograde filling material.
4. Sometimes in class VI restorations
5. Amalgam Core build up
6. complex amalgam restorations.
7. For preparation of dies.

Advantages:-
1. High compressive strength
2. Excellent wear resistance.
3. Insolubility of fluids in mouth
4. Adaptability to cavity walls.
5. Minimal post operative sensitivity.
6. Has well developed sealing ability and marginal
leakage is decreased with age.
7. Adequate resistance to fracture.
8. Economical

Disadvantages
1. Non insulating & high conductivity
2. Non esthetic
3. Initial marginal leakage.
4. Lack of edge strength when built to thin edges.
5. Tendency to molecular change that is flow,
expansion and shrinkage.
6. May produce galvanism
7. Delayed expansion and resultant pulpitis
8. Hg toxicity.
9. Tensile strength is very less.
10. Long term amalgam restorations can discolour
the tooth structure.www.indiandentalacademy.com

• Low Cu alloys when Hg contacts
surface of Ag – Sn alloy particles
amalgamation results.
• When powder is triturated, Sn &
Ag in outer portion of particles
dissolve into Hg and Hg dissolves
into powder particles.
• When solubility in Hg exceeded
than crystals of 2 binary metallic
compounds Precipitate into Hg.
• - γ1
(Ag2
Hg3
) precipitates first
and then γ2
(Sn7
Hg) phase.
• - Because the solubility of Ag
in Hg is much lower than that of
tin.
• - Ag solubility in Hg : 0.035 wt
%.

- Sn solubility in Hg : 0.6 wt %.
- Immediately after trituration, alloy powder co-exist with
liquid Hg giving plastic consistency. γ1 &
γ2
crystals grow as Hg
dissolves the alloy particles.
- As Hg disappears amalgam hardens and alloy particles are
surrounded and bound together by sold γ1,
γ2
crystals.
Setting reaction:-
Alloy particles
(β+γ) + Hg→ γ1
+ γ2
+ unconsumed alloy particle.
Voids are formed during r1
& r2
crystal growth.
γ2
– least stable & corrosive
γ – more stable

High Cu alloys
• They have improved
mechanical properties
corrosion characteristics,
better marginal integrity
and improved
performance in clinical
trials. 2 types of high Cu
alloys are

Admixed alloys
• Admixed alloys:- In
1963, Innes & Youdelis
added Ag–cu eutectic
alloy particles to
lathecut low cu
amalgam.

These alloys do stronger than amalgam made to lathe cut,
low Cu powder. They contain usually 30wt% to 55wt%
spherical high Cu powder.
• Total Cu content – 9 to 20Wt%
Setting reaction
• (β +γ ) + Ag-Cu eutectic +Hg → γ1
+n+unconsumed
alloys of both types of particles.
∀ γ 2
phase is eliminated in this reaction.
• Single composition alloys:- Each particle of these alloy
powder has same chemical composition so called single
composition major components do Ag, Cu & Sn.
• Setting reaction:- Ag Sn Cu alloy particles + Hg → γ1
+n+ unconsumed alloy particles.

Behavior of Amalgam
• Dimensional stability:- Ideally, an amalgam
should set with no change in dimensions then
remain stable for life of restoration.
• Dimensional change:- Amalgam can expand or
contract depending on its manipulation
dimensional change contract, Ideally dimensional
change should be small. Severe contraction leads
to micro leakage, plaque & secondary caries.
• Excessive expansion produce pressure on pulp
causing post operative sensitivity, protrusion of
rest.

• Mercuroscopic Expansion
• Proposed by JORGENSEN
• Extrusion at margins is promoted by
electrochemical corrosion during which
mercury from sn- hg rereacts with ag-sn
particles and produce further expansion .
• Due to occlusal stress from opponent
tooth causes local fractures.

Factors affecting dimensional change
1. Composition of the alloy
2. Percentage of Hg used in amalgamation
and manipulation by dentist.
3. Particle size
4. Particle shape
5. Trituration

Secondary expansion:
The primary contaminant affecting
dimensional stability is moisture, especially Zn
containing amalgam.
Zn+H2
O→ Zn + H2
(gas).
If Zn containing low Cu or high Cu amalgam
is contaminated by moisture during condensation or
trituration a large expansion occurs which starts after
3-5 days and continue for months, reaching values
greater then 400µm. www.indiandentalacademy.com

STRENGTH
It depends on composition of alloy, method of
manufacture and manner of mixing and packing. Set
amalgam has weak tensile and very high compressive
strength.
Factors affecting strength:-
Trituration, Hg, condensation, porosity effect of
amalgam hardening rate.
Transverse strength: Since amalgam are brittle
materials, they can with stand little deformation during
transverse strength.

Amalgam
Compressive strength
(MPa) Tensile
strength - 24
Hr (MPa)
1 Hr 7 days
Low copper
145 343 60
Admix
137 431 48
Single
composition
262 510 64
STRENGTH

• Flow & creep property of Amalgam
Creep:
Time dependent plastic deformation produced
under a stress or load. Creep is measured after setting
of amalgam. Higher the creep greater the marginal
deterioration.
Low Cu – Creep 2%
Admix – 0.4%
Single comp – 0.13%.
The creep of amalgam may be a causative factor in
reducing microleakage where the amalgam restoration
is confined to a finite space (oper dent 2006)

Flow:-
It is relative ability to plastically
deform when heated slightly above mouth
temp. Flow is measured during setting of an
amalgam and reflects the change in
dimensions of amalgam under load.

Tarnish & Corrosion:-
Tarnishing simply involves the lose of lusture
from the surface of a metal or alloy due to the formation
of surface coating. Amalgam readily tarnishes due to the
formation of a sulphide layer on the surface.
Corrosion is defined as
electrochemical destruction of a metal by reaction with its
environment.
Chemical Corrosion:-
Occurs more on occlusal surface & produces a
black Ag sulphide tarnish film.

Electrochemical corrosion :- It has potential to occur
anywhere or within the set amalgam.
Galvanic corrosion:- It amalgam is in direct contact
with an adjacent metallic restoration such as gold
crown, the amalgam is the anode in circuit results in
galvanism.
Stress corrosion:- Regions within an amalgam that are
under stress also display a greater propensity for
corrosion.
CREVICE COROSSION

Manipulation of amalgam
Factors under the control of manufacturers:
- Choice and purity of constituents of alloy.
- Preparation of constituents
- Method of melting, casting, cooling, cutting &
annealing all of which regulate expansion,
shrinkage, stability of form, crushing and
other strengths.

Factors under the control of dentist :-
- Correct amalgamation and trituration.
- Careful adaptation of matrix band
- Thorough condensation
- Free from moisture contamination during do
trituration and condensation.
- Removal of excess Hg during condensation.
- Proper removal of matrix and wedge.
- Carving to contour anatomical form.
- Polishing

Hg / Alloy Ratio:-
• A popular technique known as
Eame’s technique in which the
initial amalgam mix contains
equal amounts of mercury and
powder alloy. Powder liquid
ratio is 1:1.
• Some alloys are now available
in self activating capsules,
which automatically release Hg
into alloy chamber during first
few oscillations of
amalgamators.

PROPORTIONING:
• Amount of alloy and Hg to use
• Signifies parts by weight of Hg and alloy
• Mix of amalgam with Hg/alloy ratio 6:5
contains 54.5% Hg
• Recommended ratio for lathecut alloy—1:1
• Recommended amount of Hg for spherical
alloys –42%
• Hg is measured by volume

• It is carried out by
mechanical
amalgamator.
• An amalgamator at
3300 rpm may produce
upto 100 – 300
alternations.
• The objective is to
completely wet the
entire surface of alloy
particles with the
mercury to bring
homogeneous mass.

Over trituration results
-Mix too wet and plastic.
-Working time reduced and sets rapidly.
-Shiny wet and soft.
-Strength decreases
-Higher contraction of amalgam
-Increased Creep.

Undertrituration
- Mix will be rough and grainy consistency.
-IT is better to slightly over triturate than to
undertriturate an amalgam.
- Extended trituration may reduce plasticity, shorten
working time, and ↑final contraction.
-Reduced trituration results incomplete wetting of
surface of alloy particles by Hg have less strength ↑
porosity, rougher surface and ↑ corrosion and loss
of surface finish.

Carving ,Finishing&Polishing
• Prevents over hanging restoration at
proximal surface .
• If carving too deep at marginal areas -
Fracture.
• Carving process in direction parallel or
slightly towards the margin of tooth.

Continuation of trituration, it is done to improve
homogenicity of mix.
 After mechanical trituration, the mix
triturated in the pestle free capsule for additional 2-
3 seconds.
 Mulling also ensures cleaning of capsule
walls of the reminants of the amalgam mix, there by
delivering the mix in a single coherent consistent
mass.
MULLING

Forms of Hg:
Available in 3 forms
1. Elemental Hg (Liquid or Vapour)
2. Inorganic compounds.
3. organic compounds (Ethyl & Methyl mercury)
Organic compounds –Most toxic
Inorganic compounds-Least toxic

Sources of Hg:
Exposure to Hg can occur from different sources
such as atmosphere, drinking H2
O, food, fish.
WHO has estimated that eating sea food once a
week raises urine Hg levels to 5-20 µg/L, i.e., 2-8 times
the level of exposure from amalgam.

Sources of Hg Contamination:
1. Mercury spills
2. Expulsion of excess Hg from amalgam
3. Leakage from dispensers.
4. Improper storage of scrap amalgam
5. Amalgam condensation with ultrasonic
condensers.
6. Vapour exposure during removal or placement,finishing
or polishing of restorations

Mercury toxicity and its management
-Mercury from amalgam is released in 2 forms ie
Hg vapours and Hg ions.
-Hg ions (Hg++) are released due to corrosion. The
absorption of mercuric ions form G1 tract is minute
it has very little toxic effect.
-Hg ++ plays a role in allergic reactions.
-Hg vapours is carried to lungs from intra oral air
where it is rapidly absorbed into blood stream.
- Allergic reactions to Hg causes itching,
dermatitis, urticaria, erythema, odema, itching
occurring in face, neck, limbs.www.indiandentalacademy.com

Systemic toxic effects
-Early symptoms of Hg toxicity include anxiety,
nervousness, mild tremors in hand and depression,swollen
gums.
- High con. of Hg in blood and urine causes blurred
vision, headaches, irritability, fatigue, depression, redness
of eyes, profuse salivation, Insomnia and irritability.

Environmental hazards
Minimata disease
• Tragedy of minamata BAY in 1950.
• Symptoms of Hg poisoning during this incident
were-
 Ataxic gait
 Convulsions
 Numbness in mouth & limbs
 Difficulty in speaking

Mercury hygiene:
1. Store Hg in unbreakable tightly sealed containers.
2. Use tightly closed capsules during amalgamation.
3. Work in well ventilated areas.
4. Avoid carpeting dental operatories.
5. Avoid heating Hg / amalgam
6. Use water spray & suction for dental amalgam
restorations.
7. Not to use ultrasonic amalgam condensers.
8. Periodically determine Hg vapour levels.
OSHA (Occupational Safety and Health
Administration) has set a threshold limit value of
0.05 mg / m3
as the maximum amount of Hg vapour
allowed in a work place.www.indiandentalacademy.com

• Failures of restorations
Tarnish and corrosion
Delayed expansion
Marginal ditching
Amalgam blues
Amalgam tatoo

AMALGAM WASTE MANAGEMENT
All excess Hg, including waste, disposable capsules
and amalgam removed during condensation should be
collected and stored in well sealed containers.
Amalgam scrap should be stored under water that
contains sodium thiosulphate (photo graphic fixer).
Amalgam scrap and materials contaminated with
Hg should not be incinerated or subjected to heat
sterilization.

Newer & potentially effective waste water
treatment systems involve such as blue green algae
racks in small tank that actively concentrate Hg
waste.
Glycerin can also be used for storage with inch of
glycerin for each inch of waste amalgam to limit
vaporization of free Hg.

RECENT ADVANCES
New amalgam alloys:-
Because of concern about Hg toxicity new composition
of amalgam are been promoted as restorative material.
Gallium alloys has be suggested by PuttKanner in 1928.
Gallium melts at 28°C can be used to produce liquid
alloys at room temperature by addition of small amounts of
the elements such as In.
In this case Ga – In has been substituted for Hg in
amalgam
Recent Ga alloys contain – Ag-60% Sn – 25% Cu –
13% Pd – 20%
Liquid : Ga – 62%, In – 25%,Bismuth-0.5%

Setting reaction
Ag Sn + Ga – Ag Ga + Sn
Hardness – 128 KHN
C.S- 47.1 Mpa (7days ) (Jw, summit Op
20:241:1995)
T.S – 74.5 Mpa (7 days)

Advantages:-
1. Sets early so polishing can be carried out on
the same day.
2. They expand after mixing so better
marginal seal.
3. Negligible creep value.
4. Adequate compressive strength so given in
stress bearing areas.
5. It has good wear resistance.

Disadvantages:-
- The material is more technique sensitive because
of its sensitivity to moisture.
- The surface at Ga alloy restorations was rough,
with some tarnish present in many cases.
- Compared with high Cu amalgam, the gallium
alloy demonstrated significantly greater
expansion.
- Cleaning instrument tips is difficult and time
consuming
- Expensive
Contraindications: Not used in larger restorations as
expansion leads to fracture at weakened cusps leading
to postoperative sensitivity.www.indiandentalacademy.com

BONDED AMALGAMS
-During 1990’s some clinicians began to routinely bond
amalgam restorations to both enamel and dentine.
-After cavity preparation, the enamel & dentine can be
etched using a conventional etchant and a chemically
cured resin bonding agent 4 META (4 – Methacryloxy
ethyl trimellitate anhydride) applied to walls at cavity.
Thickness of bonding agent is 15-50µm.
-Amalgam is immediately condensed into the cavity
before the resin bond has cured with the intention to
adapt the resin to the walls and develop a mechanical
interlock between resin and the amalgam phase.www.indiandentalacademy.com

Advantages
- conservation of tooth – less need to prepare specific
retentive elements in the cavity design.
- Retention of complex restorations may be enhanced
overall.
- Resistance to cusp fracture.
- Elimination of post operative sensitivity.
Higher the thickness layer the higher bond
strength of amalgam to tooth structure
(operative dentistry 2005)

Disadvantages
-Difficulty in applying more viscous bonding agents.
-Lightly filled resin bonding agents with a high thermal
coefficient of expansion tend to pool at the gingival
margin resulting micro-leakage.
- Excess resin bond and amalgam at the margins of
cavity during condensation and make carving difficult.

Fluoride containing Dental amalgam
The recognition of anticariogenic property of si
cements stimulated interest in addition of Fl to amalgam
alloys.
In 1970s Fl amalgam introduced warren alloy, rata
alloy F.
Disadvantages:- ↓ compressive strength.
Corrosion resistance affected.
- Forsten said although there is initial high release and
uptake of Fl from amalgam but after, one Wk negligible.

consolidated amalgam-mercury free
amalgam- which have similar handling
properties of direct gold

References
Text book of dental materials –Anusavice
Operative dentistry-Sturdevant
Operative dentistry –marzouk
-Summit
Dental Materials - craig
journals
Operative dentistry 2005(30-2,228-233)
Operative dentistry 2006(31-2,161-164)

THANK YOU

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