Dental amalgam

DR MEENAL ATHARKAR
MDS
DEPT OF ENDODONTICS AND
CONSERVATIVE DENTISTRY

CONTENTS
 Introduction
 Historical Highlights
 Definitions
 Classifications Classifications
 Manufacturing
 Composition
 Amalgamation Reaction
 Indication
 Contraindication

 Advantages
 Disadvantages
 Cavity Preparation for Amalgam Restoration
 Technical Considerations
 Repair of amalgam Restorations
 Failure of amalgam restorations
 Recent Developments In Dental Amalgam
 Mercury Management In Dental Office
 Mercury Toxicity
 Summary
 Conclusion
 References

Introduction
Silver amalgam, undoubtedly is the most
commonly & widely used restorative material.
It has withstood all challenges of time & still
being used widely inspite of advent of various
other restorative materials.

 American National Standards Institute
(ANSI)/American Dental Association(ADA)
Specification No. 1 requires that amalgam
alloys contain predominantly silver & tin.
 The designation united states pharmacopoeia
ensures mercury of satisfactory purity with no
surface contamination & less than 0.02%
nonvolatile residue. The requirement is
encompassed in ANSI/ADA specification No. 6
for dental mercury.

KEY TERMS
 Alloy: A crystalline substance with metallic properties
that is composed of two or more chemical elements,
at least one of which is a metal.
 Metal: An element or alloy whose atomic structure Metal: An element or alloy whose atomic structure
readily loses electron to form positively charged ions,
and which exhibits metallic bonding, opacity and good
light reflectance from a polished surface.
 Amalgam: It is an alloy that contains mercury as one
of its constituents.

 Dental Amalgam: An alloy of mercury, silver, copper,
and tin, which may also contain palladium, zinc, and
other elements to improve handling characteristics &
clinical performance.
 Dental Amalgam Alloy: 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
 Amalgamation: The process of mixing liquid mercury
with one or more metals or alloys to form an amalgam.

 Creep: The time dependent strain or deformation
that is produced by a stress.
 Trituration: In general this is 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 mercuryof mixing the amalgam alloy particles with mercury
 Condensation: special instruments are used to
force the plastic mass into the prepared cavity.
 Eames technique: mercury:alloy ratio is 1:1

Historical Highlights
 Dental amalgam is one of the oldest filling materials
in use today. Its origin can be traced back to the
second century A.D. in China were silver amalgam
was developed for filling teeth more than a 100 years
before dentists in the west. Silver paste is mentionedbefore dentists in the west. Silver paste is mentioned
in the material medica of Sukung (AD 659).
 In 1603 Tobias Dorn Kreilius described how to make
an early type of amalgam by using copper sulphide
that had been dissolved with acids, adding some
mercury and then brought to a boil to make a liquid
that was then poured into the tooth.

 The next attempt was in France were D’Arcet’s
Mineral Cement ( 8 parts of bismuth, 5 parts of lead
, 3 parts of tin & 1 part of mercury) was introduced,
the only problem with this product was, that it too
had to be boiled at 1000 C and then poured onto the
tooth.
 In 1818 Regnart suggested the method of lowering
the fusion temperature of D’Arcet’s Mineral Cement
to 680 C by increasing the concentration of mercury.
By inventing this mixture Louis Regnart has been
donned the “Father of Amalgam”.

 In 1826, Auguste Taveau of Paris used a “silver
paste” made from filing of 5 silver coin mixed
with mercury. The silver coins also contained
tin and a small amount of copper, which gave
the mixture more plasticity and a quicker
setting time.setting time.

In 1833, two of the Crawcour brothers invaded the
United States with a cheap coin silver amalgam they
called “royal mineral succedaneum”
Their dentistry was painless since they merely sloped
and thumbed a soft plastic mix of their impure material
into cavities without removing the decay.

 Later, the fillings began to fall out, discolor the
teeth, and cause tooth fracture because of the
cheap amalgam’s expansion.
 Amalgam now had a bad reputation, despite
the fact that if used properly, it would later
prove to be an excellent restorative material

First Amalgam War:
In 1841, the American Society of Dental
Surgeons, appointed a committee to study the
amalgam problem which reported that all filling
materials, in which mercury was an ingredient,
were “hurtful both to the teeth and every part
of the mouth.

 In 1844, the society’s members were warned
that they were to sign a pledge never to use
amalgam or they would risk being expelled
from the membership.
 Townsend reported in 1855 that two amalgam
fillings he had inserted in 1834 were still “as
good as when filled” and he even gave his
personal directions for preparing the
amalgam, known as “Townsend’s Amalgam.”

In 1855, Dr. J. Foster Flagg, began testing
different amalgam formulas for posterior
restorations and added combinations of other
metals, e.g. copper, zinc, antimony, gold,
cadmium, and platinum.
In 1881, he published his book, Plastic and
Plastic Fillings, as amalgam fillings were then
popularly referred to as “plastic fillings.”

 In 1874, E.A. Bogue, stated that :-
“It will be seen that, if almost any amalgam“It will be seen that, if almost any amalgam
is used intelligently, teeth can be filled so
as not only to preserve them, but to do so
without danger to the general health, from
any element of the filling, unless it be
copper.”

 In the late 1870s, a new trend called the “new
departure” came into popularity, which signified
“total abstinence from the use of gold.”
 The “new departure” considered gold the “worst
material” and amalgam an “excellent filling
material.”

 In 1883, Dr. Alton H. Thompson stated
that “Amalgam saves more teeth than
gold, and is more generally useful.”
 Despite the research on amalgam, it was Despite the research on amalgam, it was
not until 1895 that Dr. Greene V. Black
laid the foundation for a “scientifically
balanced alloy.”

 His formula of silver and tin would “neither
shrink nor expand in setting” at ordinary room
temperature, and did not discolor.
 He also found that copper (as much as 5
percent) was beneficial.

 In 1899, a homeopathic physician stated that
the mercury in the amalgam used in filling
teeth had a deleterious action upon the
system,
 However many dentists challenged this. They
felt that amalgam made a good restorative
material from which “no mercury can be
removed so long as it remains in the mouth.”

 In 1908, Dr. E. Bumgardner stated,
 “I think that amalgam is the best filling
material in the world for the place in which itmaterial in the world for the place in which it
should be put: In a cavity that is properly
selected and properly prepared, when the
amalgam is properly mixed with a proper
alloy, and properly inserted, you have the
best filling material in the world.”

Second Amalgam War:
 In 1924, Alfred Stock, German professor of
chemistry became poisoned with mercury in his 25
years of laboratory research & published papers
on the dangers of mercury in dentistry.
 In rebuttal, Dr. F. Flury stated that mercury
poisoning was not possible with the “complex
mixtures” currently used

 In 1969, Frykholm et al. first reported a link
between amalgam and lichen planus.
 Wright, in 1971, reported a case of a positive
mercury allergy in a 9-year-old girl & when
the fillings were removed and the problem
resolved

Third Amalgam War:
 In 1981, a neurobiologist, Mats Hansen, at the
Institute of Zoo physiology at the University in
Lind, Sweden, sent a letter to the National
Board of Health of Sweden demanding an
unprejudiced evaluation of the hazards ofunprejudiced evaluation of the hazards of
dental amalgam.
 He found that the blood mercury
concentrations were positively correlated with
the number and surface area of amalgam
restorations and were significantly lower in the
group without dental fillings.

 In 1983, Haikel and his group found that mercury
vapor was released “during insertion, condensation,
carving, and removal of amalgam.”
 On December 16, 1990, CBS-TV's The "60 Minutes"
broadcast, narrated by veteran reporter Morley Safer,
was intended to alarm—to persuade its audience that
the mercury in dental fillings is a poison.

 To the contrary, said the ADA, "scientific evidence
suggests mercury amalgam is safe to use.“
 The ADA attacked CBS in the January 7, 1991
edition of its newspaper for "the irresponsible
ways in which viewers were led to the conclusion
that amalgam fillings are unsafe.“that amalgam fillings are unsafe.“
 The ADA newspaper published statements by Dr.
Harold Loe, director of National Institute of Dental
Research, criticizing CBS for having "an obvious
bias" against amalgams.

 In 1991, the ADA stated that there was “no reason
to remove amalgam restorations from a patient or
prohibit the use of dental amalgam in restorative
dentistry except in those cases of proved
sensitivity of the patient to mercury.”
 Dentists all over the country received information
packets from the ADA, including copies of the
ADA newspaper. The ADA also promoted its
message in a two-minutes video news release
sent to 700 TV stations

 Despite this statement, the Swedish
government in 1995 banned the use of
amalgam in all public health clinics for
children, and recommended that it not be
used in adults after 1997.

 In 1996, at a symposium held by the
International Association for Dental Research
concluded that :-
“exposure to amalgam fillings does not cause“exposure to amalgam fillings does not cause
serious health risks to large numbers of
individuals in the general population and,
consequently, removal of intact amalgam fillings
is not indicated.”

 In 1998, The ADA Council recommended
recycling scrap amalgam according to state and
federal laws, disposing of mercury-contaminated
items in sealed bags, and removing professional
clothing before leaving the workplace
In 2002 Gottwald and associates, concluded that In 2002 Gottwald and associates, concluded that
“the theory that amalgam-related complaints are
often an expression of underlying psychic
problems seems to be more reasonable than the
theory of mercury intoxication or the theory of an
amalgam allergy.”

 In 2003,the national Institutes of Health, U.S.
Public Health Service, Food and Drug
Administration, Centers for Disease Control and
Prevention and World Health Organization have
all stated that “dental amalgam is a safe
restorative material.”
 In May 2005, the ADA endorsed amalgam as
being safe for pregnant women

Classification of dental
amalgam alloy
Based on no. of alloy metalBased on no. of alloy metal
 Binary alloy
 Tertiary alloy
 Quaternary alloy

According to the shape of the particles
 Irregular
 Spherical
 spheroidal

According to copper content
 Low copper alloys
 High copper alloys

According to Zinc content
 Zinc containing alloys
 Zinc free alloys

According to whether the alloy is unimixed or
admixed
 Unicompositional alloy
 Admixed alloy

According to Powder particle size.
 1. Micro cut
 2. Fine cut
 3. Coarse cut

According to presence of noble metal
 Nobel metal alloy
 Non nobel metal alloy

According to compositional changes of
succeeding generations of amalgam.
 First generation amalgam was that of G. V
Black i.e. 3 parts silver one part tin (peritectic
alloy).
 Second generation amalgam alloys - 3 parts Second generation amalgam alloys - 3 parts
silver, 1 part tin, 4% copper to decrease the
plasticity and to increase the hardness and
strength. 1 % zinc, acts as a oxygen scavenger
and to decrease the brittleness.
 Third generation: First generation + Spherical
amalgam – copper eutectic alloy.

 Fourth generation: Adding copper upto 29%
to original silver and tin powder to form
ternary alloy. So that tin is bounded to
copper.
 Fifth generation. Quaternary alloy i.e. Silver,
tin, copper and indium.
 Sixth generation (consisting eutectic alloy).
The alloying of palladium (10%), silver (62%)
and copper (28%), to form a eutectic al1oy,
which is lathe-cut and blended into a first,
second or third generation amalgam in a ratio
of 1:2.

Manufacturing of alloy powder
Lathe cut alloy powder
 To produce lathe-cut alloys, the metal
ingredients are heated until melted, theningredients are heated until melted, then
poured into a mold to form an ingot.
 The ingot is cooled relatively slowly.

 After the ingot is completely cooled, it is
heated for various periods of time (often 6 to
8 hours) at 4000 C to produce a more
homogeneous distribution of Ag3Sn.
 The ingot is then reduced to filings by being The ingot is then reduced to filings by being
cut on a lathe and ball milled.
 The particles are typically 60 to 120 μm in
length, 10 to 70 μm in width, and 10 to 35μm
in thickness.

Aging:
 In general, freshly cut alloys amalgamate and
set more promptly than aged particles, and
some aging of the alloy is desirable to improve
the shelf life of the product.
 The aging is related to relief of stress in the
particles produced during the cutting of the
ingot.

 The alloy particles are aged by subjecting
them to a controlled temperature of 60 to 1000
C for 1 to 6 hours.
 Irregularly shaped high-copper particles are
made by spraying the molten alloy into water
under high pressure.

Spherical alloy powder:
 Spherical particles of low- or high-copper alloys
are produced when all the desired elements
are melted together.are melted together.
 The liquid alloy is then sprayed, under high
pressure of an inert gas, through a fine crack in
a crucible into a large chamber

 Depending on the difference in surface
energy of the molten alloy and the gas used
in the spraying process, the shape of the
sprayed particles may be spherical or
somewhat irregular.
 The size of the spheres varies from 2 to 43
μm.

 Functions of each component
SILVER:-
 Major element.
 Whitens alloy.
 Decreases creep. Decreases creep.
 Increases strength.
 Increases expansion on setting.
 Increases tarnishing resistance in resulting
amalgam.

TIN:-
 Controls the reaction between ag & hg.
 Reduces strength & hardness.
 Reduces resistance to tarnish & corrosion.
 Increases the setting time
COPPER:-
 Increases hardness & strength.
 Increses setting expansion.
 Reduce tarnish & corrosion.
 Decreses creep

ZINC:-
 Small amount –not affect setting reaction
properties of amalgam.
 Act as a scavenger deoxidiser.
 Without zn alloys are more brittle & amalgam Without zn alloys are more brittle & amalgam
formed less plastic.
 Causes delayed expansion , if contaminated with
moisture during manipulation.
 Beneficial effect on corrosion & marginal
integration.

PLATINUM:-
 Hardens the alloy & increases the resistance to
corrosion.
PALLADIUM:-
 Hardens the alloy.
 Whitens the alloy.

Amalgamation Reaction
For low copper alloy
Ag3Sn + Hg Ag2Hg3 + Sn8Hg + Ag3SnAg3Sn + Hg Ag2Hg3 + Sn8Hg + Ag3Sn
(  ) (1) ( 2) ()
54%-56% 11-13% 27-35%

Note: The properties of the hardened amalgam depends upon the proportion of each of
the reaction phases. If more unconsumed GAMMA phase is present , the stronger the
amalgam. The GAMMA-2 phase is the weakest component &is least stable to corrosion
process.

For high copper alloy
 Admixed alloy powder
1. Ag3Sn + AgCu + Hg Ag2Hg3 + Sn8Hg + Ag3Sn + AgCu
   
3 2 3 8 3
( ) (1 ) (2 ) ( )
2. Sn8Hg + AgCu Cu6Sn5 + Ag2Hg3 + Ag3Sn
(2) ( ) (1 ) ( )

 For unicomposition alloy:
AgSnCu + Hg Cu Sn + Ag Hg + AgSnCuAgSnCu + Hg Cu6Sn5 + Ag2Hg3 + AgSnCu
( +  ) (  ) (1 )


Asgar et al. J Dent Res 60(2):149-153, February 1981

 In high-copper alloys, there may be residual
gamma 2 phase, of less than 1%.( Acc. To
craig)
 Hypothesis has also been proposed, that the Hypothesis has also been proposed, that the
released mercury may partly react with Ag3Sn,
to produce Sn7Hg. (Jaro pleva. Journal of
orthomolecular medicine. 4(3): 1989)

GAMMA PHASE
This is the silver alloy phase. This is
the STRONGEST phase and has
the least corrosion.
GAMMA-1 PHASE
This consists of mercury reacting
with the silver. It is also strong and
corrosion resistant, although not as
resistant as the Gamma Phase.
This consists of the reaction with
PHASES INVOLVE IN THE SETTING OF DENTAL AMALGAM
GAMMA-2 PHASE
This consists of the reaction with
mercury and tin. This is the
WEAKEST phase and corrodes
readily. This phase is eliminated
with high copper alloys.
Eta phase
It copper-tin phase, whose crystals
interlock to prevent slippage and
dislocations at the grain boundaries
of gamma-1 particles which is a
major cause of creep in amalgam.

Properties of amalgam
1. Dimensional changes:-
An amalgam can expand or contract dependingAn amalgam can expand or contract depending
upon its usage.
Dimensional change can be minimized by proper us
age of alloy and mercury

Expansion that occurs due to reaction of Hg with alloy
components is termed primary
expansion or mercuroscopic expansion.
Expansion that occurs after 1 to 7 days due to
moisture contamination during trituration or
condensation before the amalgam mass is set, is
termed secondary expansion or delayed
expansion.

 There is an initial volumetric contraction due to
reduction in total volume of alloying elements.
 But as crystallization of various phases occurs, the
impinging of crystals against each other results in
expansion.

 Release of mercury from γ2 phase during
corrosion results in additional crystallization of
phases on reaction with unreacted γ phase,
causing further expansion.
 This is also termed mercuroscopic expansion.

Factors affecting dimensional changes are:
a) Components: Increased γ phase increased
expansion; Increased traces of Tin, decreased
expansion.
b) Particle size: Decreased size, there is contraction
initially (due to increased surface area/ unit volume
and increased dissolution of Hg) but later
expansion (due to outward thrust of forming
crystals).

C) Particle shape: Smoother shape (as in spherical
type) there is better wetting with Hg causing in faster
amalgamation resulting in contraction.
d) Hg/Alloy Ratio: Increased Hg/Alloy ratio
Increased expansion (mercuroscopic)Increased expansion (mercuroscopic)
e) Condensation: Increased condensation pressure
causes closer contact of Hg with alloy particles and
squeezing of excess Hg from the mix resulting in
contraction.

f) Trituration: Rapid trituration and longer
trituration within limits results in contraction
because of Faster amalgamation which leads to:
Decrease in particle size Decrease in particle size
 Pushing of Hg between particles
 Prevention of outward growth of
crystals

 G) Moisture contamination: Alloys containing
Zn, if contaminated with moisture before
amalgam is set, may evince delayed (or)
secondary expansion. This is due to release of
H2 gas within the restoration creating an internal
pressure of nearly 2,000 psi. Since the gas
cannot escape out, it causes expansion of thecannot escape out, it causes expansion of the
restoration. The gas is formed as follows:
Zn + H2O ZnO + H2

Effects of dimensional change
Expansion >> 4%
 Pressure on pulp pain
 High point occlusal interference pain High point occlusal interference pain
 Pressure on cavity walls tooth
fracture pain
 Expansion over the cavity margins fracture
of the restoration ("ditched amalgam")

Contraction >> than 50µ/cm
 microleakage
 secondary caries

2) Strength:
Amalgam is weaker in tension than in compression
& is a brittle material & may sometime require
reinforcement of pins embedded in dentine.reinforcement of pins embedded in dentine.

Type of amalgam
alloy
Compressive
strength (1hr)
Compressive
strength (7 days)
Tensile strength
( 7 days )
Low copper
amalgam
145 MPa 300 MPa 60 MPa
High copper admix
alloy
High copper
unicompositional

Factors affecting strength of dental amalgam:
a) Particle size: Decreased size results in increased
strength (due to increased surface area / unit
volume)
a) Particle shape: Regular uniform shape result
increased strength (due to more wettability, more
coherent mass, less interrupted coherent
interphases)

c) Microstructure of Amalgam:
 Increased γ and γ1 phases there is increased
strength
 presence of η phase there is increased strength (due presence of η phase there is increased strength (due
to prevention of grain boundary sliding)
 Increased γ2 phase, there is decreased strength

d) Porosities and voids in amalgam: Decreased
strength. Formed due to:
 Decreased trituration
 Decreased condensation pressure
Insertion of too large increments Insertion of too large increments
 Delayed insertion after trituration
 Too less Hg (amalgam non-plastic)
 Miscalculation of powder particle diameter to
occupy available spaces

e) Hg/Alloy ratio: Increased Hg/Alloy ratio,
decreased strength, because increased Hg results
in
 Decreased unreacted γ phase
 Increased γ phase Increased γ2 phase
 Increased residual Hg (weakest phase) within
amalgam

f) Trituration
 Increased trituration within limits increases strength (due to
increased coherence of matrix crystals).
 Increased trituration beyond limits decreases strength ( due to
cracking of formed crystals decreasing coherence).
g) Condensation Pressureg) Condensation Pressure
Increased pressure results in increased strength (due to removal
of excess Hg within amalgam resulting in less residual Hg)

h) Temperature
Amalgam loses 15% of its strength when its
temperature is increased from room temperature to
mouth temperature. It loses 50% of its strength when
temperature is elevated beyond 60°C (as in
overzealous polishing).
i) Corrosion activity:
Decreased corrosion activity results in increased
adhesive integrity and therefore increased strength.

3) Creep
It is defined as a time dependent plastic
deformation under constant stress occuring in
crystalline material.
According to ADA specification no 1 creep should
be below 3%.

creep%
Low copper alloy
• Fine cut
• spherical
02.6
0.8-1.5• spherical 0.8-1.5
High copper alloy
• Admix
• unicompositional
0.44
0.05-0.09

Factors influencing creep:
a. Phases of amalgam restorations
Creep rates increases with larger 1 volume fraction and
decreases with larger 1 grain sizes. 2 is associated with
high creep rates. In absence of 2, low creep rates in
single composition alloy may be due to  phase which

single composition alloy may be due to  phase which
act as barrier to deformation of 1 phase.
b. Manipulations:
Low mercury: alloy ratio, greater the condensation
pressure and time of trituration will decrease the creep
rate.

4. Corrosion:
 The general corrosion is the destructive
attack of a metal by chemical or
electrochemical reaction with its environment.electrochemical reaction with its environment.
Excessive corrosions can lead to increased
porosity, reduced marginal integrity, loss of
strength and the release of metallic products
into the oral environment.

a) Chemical Corrosion: Occurs most notably on the
occlusal surface and produces a black amalgam silver
tarnish film. Corrosion products are mainly oxides and
chlorides of tin.
b) Electrochemical corrosion: Is an important
mechanism of amalgam corrosion and occurs, whenever
chemically different sites act as anode or cathode. This
requires the sites to be connected by an electric circuit in
presence of an electrolyte (saliva). The anode corrodes,
producing soluble and insoluble reaction products.

Corrosion of various phases:
- Ag3Sn(). …..Least corrodable.
- Ag3Hg3 ( 1)
-Ag3Cu2(eutectic).
-Cu3Sn( ).
-Cu6Sn5( ).
-Sn8Hg (2).…….Most corrodable-Sn8Hg (2).…….Most corrodable

Excessive corrosion can lead to:
 Increased porosity.
 Reduced marginal integrity.
 Loss of strength.
 Release of metallic products in to the oral
environment.environment.

Indications
 In stress-bearing areas and in small-to-moderate
sized cavities in the posterior teeth.sized cavities in the posterior teeth.
 As a foundation for cast-metal, metal-ceramic
and ceramic restorations.
 When moisture control is problematic with
patients.

 Post endodontic access filling & core.
 When cost is an overriding patient concern.

Contraindications
 Esthetics is important, such as in the anterior
teeth and in lingual endodontic access
restorations of the anterior teeth.
 Patients have a history of allergy to mercury or
other amalgam components.
 A large restoration is needed and the cost of
other restorative materials is not a significant
factor in the treatment decision.

Advantages
 It is durable.
 Least technique sensitive of all restorative materials.
 Applicable to a broad range of clinical situations.
 It has good long-term clinical performance.
 Ease of manipulation by dentist.

 Corrosion products seal the tooth restoration
interface and prevent bacterial leakage.
 Long lasting if placed under ideal conditions.
 Very economical.
 Self sealing

Disadvantages
 Some destruction of sound tooth tissue.
 Poor esthetic qualities.
 Galvanic response potential exists.
 Local allergic potential.
 Concern about possible mercury toxicity that
affects the CNS, kidneys and stomach.

Cavity Preparation For Amalgam
Restorations
Steps in cavity preparationSteps in cavity preparation
a) Initial Cavity Preparation
b) Final Cavity Preparation

 Initial Cavity Preparation
1. Outline form & initial depth
2. Primary Resistance form
3. Primary Retention form
4. Convenience form

 Final Cavity Preparation
1. Removal of any remaining defective Enamel
or Dentin on Pulpal floor
2. Pulp protection
Finishing External Walls3. Finishing External Walls
4. Final Cleaning & Inspection

 Step 1: Outline Form and Initial Depth.
 Definition. Establishing the outline form means:
 (1) placing the preparation margins in the
positions they will occupy in the final
preparation, except for finishing enamel wallspreparation, except for finishing enamel walls
and margins, and (2) preparing an initial depth
of 0.2 to 0.8 mm pulpally of the DEJ position or
normal root-surface position.

CORRECT OUTLINE FORMCORRECT OUTLINE FORM
99

 Features for outline form
 preserving cuspal strength,
 preserving marginal ridge strength,
 minimizing faciolingual extensions,
 connecting two close (less than 0.5 mm connecting two close (less than 0.5 mm
apart) faults or tooth preparations,
 restricting the depth of the preparation into
dentin to a maximum of 0.2 mm for pit-and-
fissure caries and 0.2 to 0.8 mm for the axial
wall of smooth surface caries

Marginal ridge walls should be 1/2 distance fromMarginal ridge walls should be 1/2 distance from
mesial and distal pit to the crest of each marginalmesial and distal pit to the crest of each marginal
ridge.ridge.

 Step 2: Primary Resistance Form
 Definition. Primary resistance form may be
defined as that shape and placement of the
preparation walls that best enable both the
restoration and the tooth to withstand, withoutrestoration and the tooth to withstand, without
fracture, masticatory forces delivered
principally in the long axis of the tooth.

Features
 1. Relatively flat floors
 2. Box shape
 3. Inclusion of weakened tooth structure
 4. Preservation of cusps and marginal ridges
 5. Rounded internal line angles
 6. Adequate thickness of restorative material

•Pulpal Floor mesio-distally is flat and
perpendicular to the long axis of the tooth

Diverge slightly pulpo-
occlusally mesial and
distal wall extensions
protects mesial and distal
surfaces from being
undermineddistal wall extensions
(60).
undermined
106

 Step 3: Primary Retention Form.
 Definition. Primary retention form is that
shape or form of the conventional
preparation that resists displacement or
removal of the restoration from tipping orremoval of the restoration from tipping or
lifting forces

Features
1. Occlusal convergence of the preparation
wall. In class I preparation the facial &
lingual wall should converge occlusally
while in class II preparations the facial &
lingual wall of the proximal should alsolingual wall of the proximal should also
converge in an occlusal direction.
2. Occlusal dovetail prevents tipping of the
restoration by occlusal force.

 Step 4: Convenience Form.
 Convenience form is that shape or form of
the preparation that provides for adequate
observation, accessibility, and ease of
operation in preparing and restoring the tooth.operation in preparing and restoring the tooth.

Convenience form is provided by:-
Providing sufficient width for the cavity
preparation so as to allow proper access for
instrumentation.

Step 5: Removal of Any Remaining Enamel
Pit or Fissure, Infected Dentin, and/or Old
Restorative Material, if Indicated
 Definition. Removal of any remaining
enamel pit or fissure, infected dentin, and/orenamel pit or fissure, infected dentin, and/or
old restorative material is the elimination of
any infected carious tooth structure or faulty
restorative material left in the tooth after
initial tooth preparation.

 Techniques.
When a pulpal or axial wall has been established at
the proper initial tooth preparation position and a
small amount of infected carious material remains,
only this material should be removed, leaving a
rounded, concave area in the wall. The level orrounded, concave area in the wall. The level or
position of the wall peripheral to the caries removal
depression should not be altered
In case of deep dentinal caries indirect pulp capping
procedure must be attempted.

 Step 6: Pulp Protection, if Indicated.
The reason for using traditional liners or bases
is to eitheris to either
protect the pulp or to aid pulpal recovery or both

In Case of shallow preparations where the pulpal
floor is 1.5 to 2 mm in depth , use of cavity
varnish is adequate.
In case of moderate depth, a suitable base
should be applied on the pulpal floor to protect
the pulp.the pulp.
In deep cavity preparations, a calcium hydroxide
liner covered by base is necessary to protect the
pulp

 Step 7: Finishing the external wall:
Definition. Finishing the preparation walls is the
further development, when indicated, of a
specific cavosurface design and degree of
smoothness or roughness that produces thesmoothness or roughness that produces the
maximum effectiveness of the restorative
material being used

The objectives of finishing the prepared walls are to:
 (1) create the best marginal seal possible
between the restorative material and the tooth
structure,
 (2) afford a smooth marginal junction,
 (3) provide maximum strength of both the tooth
and the restorative material at and near the
margin.

 No occlusal cavosurface bevel is indicated
for amalgam.
 A butt joint between the amalgam and the
tooth creates the strongest margin for the
amalgam restoration.
tooth creates the strongest margin for the
amalgam restoration.
 Since the enamel rods in the gingival seat
are directed apically the gingival
cavosurface margins has to be beveled in
order to remove any unsupported enamel.

 Step 8: Final cleaning and inspection of
the cavity preparation:
Finally clean the preparation of any debris by
rinsing the cavity with air water spray. Clean therinsing the cavity with air water spray. Clean the
cavity preparation with a moist cotton pellet.

Manipulation and Technical Consideration of
Dental Amalgam:
 Selection of Alloy:
The selection of an alloy involves a number ofThe selection of an alloy involves a number of
factors including particle size, particle shape,
and composition, particularly as it relates to the
elimination of the 2 phase and the presence or
absence of zinc.

 It is estimated that over 90% of the dental amalgam
currently placed are high copper alloys. The majority
of these alloys are spherical unicompositional or
admixed types being selected.
 Another criteria depend on the presence or absence
of zinc. If an alloy contains more than 0.01% zincof zinc. If an alloy contains more than 0.01% zinc
such material will show excessive corrosion and
expansion in moisture contamination. Alloy not
containing zinc, will be less plastic, less workable and
more susceptible to oxidation.

Mercury: Alloy Ratio:
There are two Hg concentration techniques:
 1. High mercury technique.
 2. Minimal mercury technique (Eames
technique).

High Mercury Technique:
 In this, the initial amalgam mix contains little
more mercury than needed for the powder
(52-53% Hg) producing a very plastic mix.
 Because of deleterious effect of high mercury
content on physical and mechanical
properties of amalgam, it is not used these
days.

 Special indications may be pin amalgam
restoration or very large restoration where
more wetting of amalgam is required. But with
advent of amalgam bond, this can be
eliminated.

Minimal Mercury Technique:
 In 1959, W. Eames was the first to promote low
mercury: alloy ratio (mercury: alloy ratio is 1:1).
This method reduces the mercury content up to
43% for high copper single composition alloys43% for high copper single composition alloys
compared to 55% for lathe cut low copper alloys.
The excellence of clinical restoration placed by this
technique depends on proper manipulation including
propositioning of mercury and alloy.

Trituration:
 In general, trituration means 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.
 Originally, the alloy and mercury were mixed, and
was triturated by hand with a mortar and pestle.
Now a days, mechanical amalgamation saves time
and standardizes the procedure.

HAND TRITURATION MECHANICAL
TRITURATION
 Mix variable
 Trituration time more
 Excess mercury to be
removed by squeezing
 Mix uniform
 Less
 No need to squeeze
since proportion of
mercury and alloy is
proportioned by the
 Spillage and waste of
material
 Untidy
 Risk of environmental
mercury contamination
proportioned by the
manufacturer
 Material conserved
 Tidy
 Reduced risk

Objectives of Trituration are:
 1) To provide proper amalgamation of the mercury
and alloy and to achieve a workable mass of
amalgam within a minimum time, leaving sufficient
time for its insertion into a cavity preparation and
carving to the predetermined tooth anatomy.
 2) To remove the oxide layer, as alloy particles are
coated with a film of oxide, which is difficult for the
penetration of mercury. The oxide layer is
removed by abrasion when the alloy particle and
mercury are triturated.

 3) To pulverize pellets into particles, that can be
easily attacked by the mercury.
 4) To reduce particle size so as to increase the
surface area of the alloy particle per unit
volume, leading to a faster and more complete
amalgamation.amalgamation.
 5) To keep the amount of 1 or 2 matrix crystal
as minimal as possible, yet evenly distributed
throughout the mass for proper binding and
consistent, adequate strength.

 Time of trituration on amalgamation ranges
from 3-30 seconds. Variations in 2-3 seconds
can also produce a under or over mixed
mass.

 Over-trituration:
1. Alloy will be hot, hard to remove from the
capsule & too plastic to manipulate.
2. reduce plasticity,
3. Shorten working time
4. Increase final contraction.

 Under-trituration: Alloy will be dry, dull and
crumbly
Reduced tritutation may result in:
1. Incomplete wetting of the surfaces of the alloy
particles by mercury.
2. A weak interface between the matrix
(gamma1) and the particles.
2. A weak interface between the matrix
(gamma1) and the particles.
3. Lower strength.
4. Increased porosity.
5. A rougher surface.
6. Increased corrosion.
7. Loss of surface finish.

 Normal Mix:
1. Shiny appearance separates in a single mass
from the capsule.
2. It has the best compressive & tensile
strength.strength.
3. Carved surface retained its lusture after
polishing

 Mulling Operations:
Mulling is actually a continuation of trituration.
Mulling is mainly done to improve the
homogeneity of the mass and to assure ahomogeneity of the mass and to assure a
consistent mix with improved texture.

It can be done in two ways.
 Mix is place in a dry piece of rubber dam and
vigorously rubbed between the first finger and
the thumb. This process should not exceed 2-5
seconds.
 After trituration, pestle can be removed from
the capsule and the mix is triturated at a low
speed for 2-3 seconds. This process also
allows cleaning of capsule.

Significance of mulling
-to remove residual mercury content because
I. Residual mercury increase by 1% leads to decrease in
strength by 1%strength by 1%
II. If residual mercury is more then 55%wt the hardening
expansion is increased
III. Creep rate is increased

 CONDENSATION:
The condensation of the amalgam mass into the
tooth cavity is one of the most important steps in
the operation of forming an amalgam restoration.

 The objectives of condensation are:
 To squeeze the unreacted mercury out of the
increments during building up the restoration,
thereby preventing entrapment of mercury.
 To bring the strongest phases of amalgam close
together, thereby increasing the final strength of the
restoration.restoration.
 To adapt the plastic amalgam mix to cavity walls
and margins, thereby increasing retention and
minimizing microleakage.
 To reduce the number of voids, and keep matrix
crystals continuous.

 When to condense?
 Mass should be condensed as early as
possible after trituration
 If the time lapse between trituration and
condensation is more than 3 to 4 mins the
mix should be discarded because the
partially hardened mass is difficult to
condense properlycondense properly
 Types of condensation
1. Hand condensation
2. Mechanical condensation
3. Ultrasonic condensation

Manual Condensation:
 The mixed material is packed in increments. Each
increments is carried to, the prepared cavity by
means of a amalgam carrier.
 Once inserted, it should be condensed
immediately with sufficient pressure approx. 4 to 8
 Once inserted, it should be condensed
immediately with sufficient pressure approx. 4 to 8
pounds.
 Condensation is started at the center, and the
condenser point is stepped little by little towards
the cavity wall.

Placement
Place the amalgam into the cavity in relatively
small increments and condense using:
 Lathe-cut alloy: Small condenser.
 Blended alloy: Small condenser.
 Spherical alloy: Large condenser.

METHOD OF HAND CONDENSING
1. The shape of face of condenser should be
selected so as to fit in the outline form of the
cavity
2. Small increments one at time are added2. Small increments one at time are added
3. Cavity is slightly overfilled
4. The direction of force is as much as possible
perpendicular to walls and floor of the preparation

5.Condensation pressure of 4 to 8lb
6.The condensation should preferably start from the centre
7.In class 2 cavity the condensation is done from the cervical area
8.factors regulating the pressure, direction of condensation and the
size of increments used .
Pressure=force/area of cross sectionPressure=force/area of cross section
Thus increasing the area of condensation decreases the amount of
pressure acting on the bottom of condenser
9.If the force of condensation is increased unduly the mass of
amalgam under the condenser goes along the instrument rather
than being condensed

Mechanical Condensation:
 Mechanical condensers are more useful and
more popular for condensing lathe cut alloys,
when high condensation forces are required.
With the development of spherical alloy, the
need for mechanical condenser wasneed for mechanical condenser was
eliminated.
 Ultrasonic condensers are not recommended
because during condensation they increase
the mercury vapour level to value above the
safety standards for mercury in dental office.

Precarve Burnishing:
 Immediately after discarding the blotting mix, a
large rounded burnisher is used in light strokes
from amalgam surface to tooth surface onfrom amalgam surface to tooth surface on
occlusal portion. Inaccessible areas, such as
proximal positions of the restoration should be
similarly burnished using beaver tail burnisher

This process has four objectives.
1. It is continuation of condensation, in that it will
further reduce the size and number of voids on
the critical surface and marginal area of the
amalgam.
2. It brings any excess mercury to the surface, to2. It brings any excess mercury to the surface, to
be discarded during carving.
3. It will adapt the amalgam further to cavosurface
anatomy.
4. It conditions the surface amalgam to the carving
procedure.

Carving:
 Carving is the anatomical sculpturing of the
amalgam material.
 Carving is begun soon after the condensation.
But, the amalgam should be hard enough to offer
resistance to carving instrument. A scarping or
"ringing" (amalgam crying) should he heard. If
carving is started too soon, amalgam will pull
away from margins.

 Post carve burnishing
It is done to remove scratches, irregularities on
the amalgam surface, facilitating easier and
efficient finishing and polishing. The combination
of frictional heat and pressure with theseof frictional heat and pressure with these
materials achieve the desired results.

Objectives:
1. To produce a restoration with no underhangs i.e. all
marginal details of the cavity preparation are
completely covered with amalgam without any
shouldering or shelving of tooth structure.
2. To produce a restoration with the proper2. To produce a restoration with the proper
physiological contours.
3. To produce a restoration with minimal flash.
4. To produce a restoration with functional non-
interfering occlusal anatomy.

5. To produce a restoration with adequate,
compatible marginal ridges.
6. To produce a restoration with proper size,
location, extend and interrelationship of contact
areas.
To produce a restoration with physiological7. To produce a restoration with physiological
compatible embrasures.
8. To produce a restoration not interfering in any
way with the integrity of the periodontium. Thus,
enhancing its health.

Finishing and Polishing:
 Finishing can be defined as the process,
which continues the carving objectives,
removes flash and overhangs and correctsremoves flash and overhangs and corrects
minimal enamel underhangs.
 Polishing is the process which creates a
corrosion resistant layer by removing scratches
and irregularities from the surface.

 Usually, 24 hours should pass after amalgam
insertion before any finishing and polishing
commences.
 This can be done using descending grade
abrasive, eg. rubber mounted stone or rubberabrasive, eg. rubber mounted stone or rubber
cups. For final finishing i.e. obtaining, a metallic
lusture, is always done with a polishing agent
(precipitated chalk, tin or zinc oxide).

RECENT ADVANCES IN DENTAL AMALGAM:
BONDED AMALGAM RESTORATION:
Despite all the advantages, amalgam has its own
limitations as a restorative material such that it lacks
adhesion to the tooth structure and thereby requires
considerable removal of more intact tooth structure to
provide long term retention.provide long term retention.
To combat the limitations, adhesive systems
designed to bond amalgam to enamel and dentin
have been introduced in an effort to compensate for
the disadvantages.

The advantages of adhesive amalgam restoration over
non-adhesive treatment alternatives are :
1. It is a treatment option for extensively carious posterior
teeth, with a lower cost than either cast metal
restoration or metal-ceramic crowns.
2. It allows use of amalgam in teeth with low gingivo-
occlusal height which is not possible in conventional
amalgam, amalgam with pins, inlays, onlays, complete
cast crown restoration.cast crown restoration.
3. It permits more conservative cavity preparations, as it
does not require additional retention in form of groove,
pins etc.
4. It can eliminate use of retention pins and inherent risk
involved with it such as periodontal perforation, pulp
exposure, stress patterns, cracking, crazing etc.

5. It reduces marginal leakage to minimal.
6. It reinforces the tooth structure weakened by
caries and cavity preparation, which is not with pin
amalgam.
7. It reduces incidence of post-operative sensitivity
commonly observed with amalgam restorations.commonly observed with amalgam restorations.
8. It reduces incidence of marginal fracture and
recurrent caries. It allows biologic sealing of P-D
complex by formation of hybrid layer.
9. It can be done in single sitting.
10. It allows for amalgam repairs.

Chemical composition:
 Amalgam bond plus:
 Activator/Conditioner: 10% citric acid, 3% ferric
chloride.
 Adhesive: HEMA (Hydroxyethyl methacrylate).
 Catalyst: TBB(Tri-N-Butyl-Borane oxide).
 Base: 4META(4-Methacryloxyethyl trimellitate
anhydride).

TECHNIQUE:
 After proper isolating and anesthesia, all carious
tooth structure is removed.
 Surface is etched with 10% phosphoric acid gel.
Then washed for 15 seconds and dried with air jet.
After drying, conditioned enamel has dull white
appearance.appearance.
 Three coats of primer A and primer B are applied till
shiny aspect caused by hydrophilic resin
incorporated in primers is obtained.
 The dentin-enamel bonding agent is applied with
brush and freshly triturated amalgam is condensed
into cavity before the auto curing bonding agent is
polymerized.

LIMITATIONS OF BONDED AMALGAM:
 a) Time consuming and may be technique
sensitive due to bonding agents used.
b) Requires practitioner to adapt to new b) Requires practitioner to adapt to new
technique.
 c) Increases cost of amalgam restorations.

 GALLIUM ALLOYS:
Recent controversy surrounding mercury has
renewed interest in developing a mercury free
restorative material with physical properties
comparable to dental amalgam.
Mercury free metallic restorative materials
proposed as substitute for mercury containing
amalgam are gallium containing materials and
pure silver and/or silver based alloys.

ADVANTAGES OF GALLIUM BASED ALLOYS:
 Rapid solidification.
 Good marginal seal by expanding on
solidification.
 Heat resistant.
 The compressive and tensile strength increases The compressive and tensile strength increases
with time comparable with silver amalgam
 Creep value are as low as 0.09%
 It sets early so polishing can be carried out the
same day
 They expand after setting therefore provides
better marginal seal

Composition:
Alloy:
 Silver (Ag) 60%
 Tin (Sn) 25%
 Copper (Cu) 13%
 Palladium (Pd) 20% Palladium (Pd) 20%
Liquid:
 Gallium (Ga) 62%
 Iridium (Ir) 25%
 Tin (Sn) 25%

Limitations:
1. In early gallium alloys, surface roughness, marginal
discoloration and fracture were reported. With
improvement in composition, these defects were
reduced but not eliminated
2. The gallium alloys could not be used in larger
restorations as the considerable setting amount ofrestorations as the considerable setting amount of
expansion leads to fracture of cusps and post
operative sensitivity.
3. The cleaning of instruments tips is also difficult
4. It is also less popular because it is costlier than
amalgam.

Mercury Free Direct Filling Amalgam Alloys:
 These are amalgam substitutes developed by the
American Dental Association at the National Institute Of
Standard And Technology (ADA-NIST) .
 They use a silver-coated silver tin alloy particles that
can be cold welded by compaction to form a restoration.can be cold welded by compaction to form a restoration.
 A fluoroboric acid solution is used to keep the surface
of the alloy particles clean.
 These alloys can be condensed into the prepared cavity
similar to the compaction of direct gold.

Drawbacks:
 The material hardens and become brittle during
compaction.
It exhibits internal voids and poor adaptation. It exhibits internal voids and poor adaptation.

Silver Alloy Admix Glass Ionomer Cement:
 This consists of physically blending silver alloy
powder with the glass powder in the ratio of 1:7
and mixing it with glass ionomer liquid.and mixing it with glass ionomer liquid.
 This simple blending of alloy & glass powder
increases the strength & abrasion resistance of
the cement to some extent.

 Restorative reinforced GICs have a number of
clinical uses such as for bases, restorations (class
V, minimal class II. e.g. tunnel preparation and
primary teeth), sealants, repairs of castings and
temporary or emergency procedures.
 However, the more common use of these cements However, the more common use of these cements
is probably for core buildups where moderate
strength and cariostatic effects are required. The
tensile strength of these cements is not high,
therefore, they still require considerable support
from remaining tooth structure.

FAILURES OF DENTAL AMALGAM
“Clinical failure” is the point at which a restoration
is no longer serviceable or when the restorationis no longer serviceable or when the restoration
poses several risks if it is not replaced.

 Signs of Failure Of Amalgam Restoration:
Fracture lines Marginal Ditching
Proximal overhangs

Recurrent caries Amalgam Blue &
Amalgam Fracture

 Voids
 Improper proximal contacts

 Mercury Toxicity:
 Like all other materials, mercury has the
potential for being hazardous, if not used
properly.
 Though mercury present in amalgam always
been under controversy, the contribution of
mercury to overall body burden has been
relatively low.

Forms of mercury:
 Mercury is available in 3 forms
1. Elemental mercury (liquid or vapour)
2. Inorganic compound
Organic compound3. Organic compound

 Elemental mercury is most volatile of the three and
mercury vapor in air is most predominant form of
elemental mercury. It is rapidly absorbed into blood
via lungs. It can cross the blood brain barrier .
 Inorganic compound of mercury
 Source of this is drinking water and food. They are
poorly absorbed and do not accumulate into bodypoorly absorbed and do not accumulate into body
tissue and well excreted
 Organic compound of mercury
 Source – drinking water and food (particularly sea
food)
 Some organic compounds (methyl mercury) are
highty toxic at low concentrations.

 The normal daily intake of mercury is 15 g from
food, 1 g from air ad 0.4 g from water.
 The maximum allowable level of mercury in the
blood is 3 g/L.
 Naleway C. et al (1991) investigated the average Naleway C. et al (1991) investigated the average
mercury levels among dentist in 1980 – 19.5
g/L, 1986 – 6.7 g/L, 1991 – 4.9 g/L. He
concluded, the mercury levels decreased due to
mercury hygiene techniques.

Mercury released in dental office is in forms of
mercury vapors. Mercury vapors are released
during all procedures such as mixing, setting,
polishing and removal, mercury vapors has also
been reported to be released during mastication
or drinking of hot beverages.or drinking of hot beverages.

The release of mercury is:
 Greater for low-copper amalgams, because of
corrosion related loss of tin and increased
porosity.
 Greater from Unpolished surfaces
 Increased by tooth brushing, which removes a Increased by tooth brushing, which removes a
passivating surface oxide film-although this re-
forms rapidly.

Concentration of Mercury:
 The occupational safety and health
administration has set a threshold limitadministration has set a threshold limit
value (TLV) of 0.05 mg/m3 as maximum
amount of mercury vapour allowed in
the work place.

Sources of Mercury Exposure in Dental Office:

Mercury Management:
 Symptoms: Know the potential hazards and
symptoms of mercury exposure such as
development of sensitivity and neuropathy.
 Hazards: Know the potential source of mercury
vapours such as (a) Spills, (b) dispensers, (c)
Polishing amalgam, (d) Removing amalgam.Polishing amalgam, (d) Removing amalgam.
 Ventilation: Provide sufficient ventilation by
ensuring that the airflow is reasonably high and
that fresh air is brought into the office in path
from waiting room, through the outer office and
expelled to the outer building area without
contaminating other building areas.

 Monitor office: Monitor the mercury vapour level
in the office periodically (this may be done using
dosimeter badges) as recommended by OSHA.
 Monitor personnel: By periodic urine analysis
(the average mercury level in urine is 6.1 g/L for
dental office personnel.
 Mercury spills: On the floor covering can be
decontaminated by replacing them. There is no
effective treatment for removing liquid mercury
from carpet.
 Pre-capsulated alloy: Use pre-capsulated alloy to
eliminate possibility of bulk spills.

 Amalgamator cover: Use amalgamator fitted
with cover to stop aerosol produced during
trituration.
 Handling care: use care by avoiding contact
with mercury or freshly mixed amalgam,with mercury or freshly mixed amalgam,
 Evacuation system: Use high volume
evacuation, when finishing and removing
amalgam. Use rubber dam

 Recycling: Scrap dental amalgam should be
col1ected and stored under water, glycerin or
spent x-ray fixer in a tightly capped jar. Spent x-ray
fixer has an advantage of controlling mercury
because it is a source of both silver and sulfide
ions for reaction to solid product.
 Contaminated items: Dispose of mercury Contaminated items: Dispose of mercury
contaminated items in sealed bags according to
applicable regulations.
 Clothing: Wear professional clothing only in the
dental operatory.

CONCLUSION
 Dental amalgam has been used in dentistry
for over 170 years. From the conventional
composition of dental amalgam which wascomposition of dental amalgam which was
proposed by Dr. G. V. Black to the new
generation adhesive, amalgam has come a
long way with the advent of adhesive
materials, which actually bonds amalgam to
the tooth structure, the protocol for placement
of amalgam restoration has changed.

 There are certain advantages inherent with
amalgam such as technique insensitive,
excellent wear resistance, less time
consuming, long life which are not present in
the newer materials, these factors will
continue to make amalgam the material ofcontinue to make amalgam the material of
choice for many more years to come.

 REFERENCES:
 Stephen. C. Boyne, Duane. F. Taylor, “Dental materials”, The
Art and Science of operative Dentistry, Mosby 3rd Edition
1997:219-235.
 Kenneth J Anusavice, D.M.D., PhD., “Philip’s Science of
Dental materials”, W.B. Saunders Company, 10th Edition
1996: 361-410.
 M.A. Marzouk D.D.S. M.S.D. et al, “Operative Dentistry
Modern theory and Practice”, IEA inc 1997:105-120.Modern theory and Practice”, IEA inc 1997:105-120.
 Craig, “Science of Dental Materials”.
 Vimal. K. Sikri, “Silver Amalgam”, Text book of Operative
Dentistry” CBS publishers, 1st Edition 2002, 204-242.

Dental amalgam

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