Amalgam

Technical considerations of
Silver Amalgam
1
PRESENTED BY,
VISHNUJA V R NAIR
1ST YEAR MDS
DEPT OF CONSERVATIVE
DENTISTRY AND ENDODONTICS

CONTENTS
INTRODUCTION
CLASSIFICATION
COMPONENTS OF AMALGAM
BASIC SETTING REACTION
GENERAL CONSIDERATIONS FOR
AMALGAM RESTORATIONS
MANIPULATION
o SELECTION OF ALLOY
o PROPORTIONING
o TRITURITION
o CONDENSATION
o BURNISHING
o CARVING
o FINISHING
o POLISHING
INDICATIONS AND
CONTRAINDICATIONS
ADVANTAGES AND DISADVANTAGES
MODIFICATION OF AMALGAM
MERCURY MANAGEMENT
CLINICAL LONGEVITY OF AMALGAM
REVIEW OF LITERATURE
CONCLUSION
REFERENCES
2

3
INTRODUCTION
ANSI/ADA Specification No. 1
Amalgam is one of the oldest of all materials used for restoring a carious
lesion.
Dental amalgam is an alloy made by mixing mercury with silver-tin alloy
to which varying amount of copper and small amount of zinc are
added.
Louis Regnart (1818)- Father of amalgam.

CLASSIFICATION
1.According to the Number of
alloyed metals
• Binary alloy (Eg: Ag, Sn)
• Ternary alloy (Eg: Ag, Sn, Cu)
• Quaternary alloy (Eg: Ag, Sn,
Cu , In)
2.According to Shape of
powdered particles
• Spherical
• Spheroidal
• Lathe cut
4
Roberson T, Heymann HO, Swift Jr EJ. Sturdevant's art and science of operative dentistry. Elsevier Health Sciences; 2006 Apr 13.

3. According to powder particle
Size
• Microcut
• Finecut
• Coarsecut
5. According to presence or
absence of Zinc
• Zinc free  Less than .01%
• Zinc containing  More than
0.01 %
4. According to Copper contents:
• Low Copper Less than 6%
• High Copper More than 6%
6. According to whether powder
contains unmixed or admixed
alloys
• Dispersed/blended/Admixed alloys
• Unicompositional/single
compositional
5

TYPES OF DENTALAMALGAM ALLOYS
Low copper alloy
High copper alloy
a) Admixed b)Uni-compositional
Low Cu alloy (5% or less)
High Cu alloy (13%- 30%)
High compressive strength
Better marginal adaptation
Low creep(0.1%-1%)
Least stable and corrosive
High creep (1-8%)
6

Elements Increases Decreases
Silver (Ag) Whitens the alloy, Strength, Setting
expansion, Resistance to tarnish.
Flow and Creep
Tin (Su) Creep, Rate of Amalgamation, corrosion ,
contraction
Strength, Hardness, speed
of setting
Copper (Cu) Strength, Hardness,
Setting expansion, tarnish
Creep
Zinc (Zn) Act as a plasticizer, Delayed expansion,
corrosion.
Brittleness,
COMPONENTS OF ALLOY POWDER
7
Materials used in dentistry- S.Mahalaxmi

THE BASIC SETTING REACTION OF AMALGAM
Alloy Particles for Amalgam + Mercury Dental Amalgam + Nonreacted Alloy Powder
Particles
• g phase (Ag3Sn): strongest phase which occupies the maximum available space
in the volume of restoration.
• g1 phase (Ag2Hg3): noblest phase, most resistant to tarnish and corrosion.
• g2 phase (Sn7–8Hg): weakest phase, more prone to corrosion and creep.
8
LOW COPPER ALLOYS

9
Ag3sn + AgCu + Hg Ag2Hg3 + Sn8Hg + Ag3Sn + AgCu
Sn8Hg + AgCu Cu6Sn5 + Ag2Hg3 + Ag3Sn
Initial Reaction
Final Reaction
HIGH COPPER ADMIXED ALLOY
HIGH COPPER UNICOMPOSITIONAL
Ag3sn + Cu3Sn + Hg Cu6Sn5+ Ag2Hg3
Epsilon reduces creep,and prevent formation of gamma2 phase
Eta phase strengths the bond between alloy particles and gamma1 phase. It increases resistance to deformation
and resistance to tarnish and corrosion
Craig’s restorative dental materials 12th edition

GENERAL CONS
IDERATION
FOR AMALGAM
RE
STORATION
• Amalgam is effective as a direct restorative material because of its easy insertion into a
tooth preparation and, when hardened, its ability to restore the tooth to proper form and
function.
• The required tooth preparation form must allow the amalgam to
1. Possess a uniform specified minimum thickness for strength (so that it will not lex
and fracture under load)
2. Produce a 90-degree amalgam angle (butt-joint form for maximum edge thickness) at
the margin, be mechanically retained in the tooth.
3. Amalgam restorations initially leak and therefore require steps to protect from pulpal
sensitivity until self-sealing is able to occur.
10
Sturdevant Operative Dentistry 7th Edition

Technical consideration of Amalgam Restoration
 Selection of alloy
 Proportioning
 Trituration
 Mulling
 Matricing
 Condensation
 Carving
 Burnishing
 Finishing and polishing
12

SELECTION OFALLOY
Shape of
alloy
Size of
alloy
Composition of
alloy
13
Since low copper and zinc containing
alloys have the disadvantages of g2
phase and hygroscopic expansion,
they are not used nowadays.
The high copper alloys are used in
more than 90% of the cases, the
majority of which are the spherical
single compositional or admixed
types, due to their high early
strength, low creep, better marginal
adaptation, and good resistance to
corrosion.

oSmaller the particle size, higher is the strength, lesser expansion, more easily adopted
into the cavity walls and more easily polished.
oOnly finer particle-sized low copper lathe-cut alloys can be used because of improved
surface finish during carving and finishing, enhanced clinical convenience, such as the
ease of dispensing from mechanical propositioning devices.
oMoreover, lathe-cut alloys require almost 50% or more mercury to obtain adequate
plasticity during trituration; hence, its use is not recommended.
oSince spherical alloys are smoother and consist of various sizes of spheres (2–3 mm)
that allow compact packing of the particles with a low area to volume ratio, they
generally require less mercury (about 42%) for trituration.
14

• The lathe-cut and spherical alloys react differently to condensation
forces. Due to their shape, spherical alloys cannot offer much
resistance to the condensation pressure and require much
less force than lathe-cut alloys during condensation.
• Another criterion depends on the presence or absence of zinc. If
an alloy containing more than 0.01% zinc is used, it exhibits
excessive corrosion and expansion if moisture contamination
occurs.
• The alloy that does not contain zinc will be less plastic, less
workable, and more susceptible to oxidation.
15

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SHAPE OF ALLOY
Spherical alloys are preferred because it:
Gives better finish, marginal adaptation
Good strength
Requires less condensation forces
Requires less mercury (42% conc of Hg ) due to low surface area
compared to lathe cut which requires 50% or more Hg.
High Copper alloy is preferred over low Copper since :
- Less creep due to absence of gamma2 phase and better corrosion
resistance.

TYPE OF ALLOY FEATURES
Spherical alloy Tend to flow into and adapt themselves
more readily into internal cavity
walls.(class I cavity)
Admixed alloy Does not flow ahead of the condenser,
gets adapted itself to the angles and
corners within the confines of the
matrix and developing a positive
contact with the adjacent tooth.
(class I and II cavity)
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 Alloy powder & mercury
 Disposable capsules with pre proportioned alloy powder &
mercury
 Preweighted pellets or tablets & mercury in sachets.
 Self activating Capsules.
MODE OFSUPPLY
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PROPORTIONING
Manipulation
Alloy Composition
Particle Size and Shape
Heat Treatment
Condensation Technique
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PROPORTIONING OF ALLOY TO MERCURY
There are different ways of proportioning:
Weighing and triturating: this is ideal but time consuming
Volume dispensing:
Widely used-however it is difficult to dispense any powder
accurately by volume
Pre-weighed capsules of alloy powder and Mercury separated by a membrane:
Disposable capsules containing pre-proportioned amounts of mercury and alloy are
widely used. Just before the mix is triturated, the membrane is ruptured by compression
of the capsule.
Phillip’s Science of Dental Materials 11th edition

DISPOSABLE CAPSULES
- Disposable capsules
contain preproportioned
alloy particles and mercury
separated by a membrane.
Before use the membrane
is ruptured by compressing
the capsule
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Some alloys are now available in self-activating capsules, which automatically release the
mercury into the alloy chamber during the first few oscillations of the amalgamator.
Size: Capsules containing 400,600,800 or 1200 mg of the alloy and
appropriate amount of Hg according to the size of the cavity.

MERCURY / ALLOY RATIO
For conventional mercury added systems 2 techniques were used for mercury
reduction:
a) By squeezing or wringing the mixed amalgam in a squeeze cloth before insertion
into the prepared cavity.
b) Mercury rich amalgam was worked to the top during condensation of each
increment, and this excess was removed as the amalgam mix was built up to form a
restoration.
23
Marzouk

MINIMAL MERCURYTECHNIQUE
EAMES TECHNIQUE
(1959)
RECOMMENDED HG/ALLOY RATIO
1:1 25
The most obvious method for reducing the mercury content of the restoration is to reduce the
original mercury / alloy ratio. The present day alloys are designated for manipulation with
reduced mercury / alloy ratios just enough to get a coherent plastic mass.
Marzouk

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TRITURITION
Marzouk
• The purpose of trituration is to mix the amalgam alloy intimately with mercury so
as to wet the surface of the powder particles to allow the reaction between
liquid mercury and silver alloy.
• There is always an oxide layer of the alloy surface that hinders diffusion of mercury
into the alloy.
• This film must be disrupted so that a clean surface of alloy can make intimate
contact with the mercury. The oxide layer is removed by abrasion when the alloy
particles and mercury are triturated.

To achieve a
workable mass of
amalgam within a
minimum time.
To remove
oxides from the
powder particle
surface,
facilitating direct
contact between
the particles and
the mercury
To pulverize pellets
into particles that can
be easily attacked by
the mercury.
OBJECTIVES OF TRITURATION
Marzouk
27

To reduce particle
size so as to increase
the surface area of the
alloy particles per
unit volume, leading
to a faster and more
complete
amalgamation.
To keep the gamma1
matrix crystals as
minimal as possible
yet evenly distributed
throughout the mass
for proper binding
and consistent
adequate strength
To dissolve the
particles or part of
the particles of the
powder in mercury,
which is a
prerequisite for the
formation of the
matrix crystals
Marzouk
28

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HAND MIXING BY THE MORTAR AND PESTLE METHOD
In this a glass mortar of parabolic shape and a pestle is used.
The time of mixing is 30-40sec with a force of 800-900 gm being applied.
The mixed mass should be homogeneous, smooth, should not stick to walls of mortar and
pestle and should form a lump.
Factors affecting it include:
• Pressure exerted on the mix
• Number of revolutions per minute
• Inclination of the pestle relative to the mortar
• Surface roughness of both mortar and pestle

MECHANICAL TRITURATION
o Trituration of amalgam alloy and Mercury is done with a mechanical mixing device
called AMALGAMATOR-Time ranges from 3 t o 3 0 s e c o n d s .
30
o This saves time, standardizes the procedure, produces an even mix, and is
advantageous for use with a low Mercury: Alloy ratio.

31
o The main mixing mechanism of a mechanical triturator is a reciprocating arm that
holds the capsule under a protective hood. The purpose of the hood is to confine
mercury that might escape into the room or to prevent a capsule from being
accidentally ejected from the triturator during trituration.
o A modern triturator is often microprocessor controlled and contains preset trituration
programs for a number of materials. A cylindrical metal or plastic piston of smaller
diameter than the capsule is inserted into the capsule, and this serves as the pestle.
Spherical alloys often do not need a pestle.
o A triturator should be used at the speed recommended by the alloy manufacturer.
o Self-activating capsules are usually very sensitive to trituration speed.

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ADVANTAGES
1. Uniform and reproducible mix can be attained.
2. Minimal trituration time is required.
3. A greater Alloy:Mercury ratio is used for preparing the mix as they are proportioned by the
manufacturer.
4. Atmospheric mercury contamination is reduced.

For a given mercury / alloy ratio, increased trituration time and /or speed shortens the
working and setting times.
Low, medium and high speed amalgamators operate at about 3200-4400 cycles per
minute.
Coherence time:
It is defined as the minimum mixing time required for an amalgam to form a single coherent
pellet.
It has been found that the compressive strength, dimensional change and creep are
optimized if the mixing is carried out for a time of 5 times the coherence time.
33

COMPRESSIVE STRENGTH OF AMALGAM TRITURATED BY A
HIGH-SPEED AMALGAMATOR AND BY AN ULTRAHIGH-SPEED
MIXER
• Four frequently used dental amalgam alloys were selected for this study. Each of the alloys
was triturated in a high-speed amalgamator and in a ultrahigh-speed mixer with and without
a pestle in the capsule. The compressive strength of these triturated amalgam was compared.
• Alloys triturated in the high-speed amalgamator satisfactorily attained their maximum
crushing strengths when mixed according to each manufacturer's instructions for that alloy.
• At most of the times tested, alloys triturated with the ultrahigh-speed mixer with the pestle
in the capsule reached slightly higher compressive strengths than those mixed in the usual
high-speed amalgamator.
• It is concluded that the ultrahigh-speed mixer is an instrument capable of producing
satisfactory trituration of the alloys studied when compressive strengths are used as the
criterion. 34
Osborne JW, Ferguson GW, Sorensen SE, Gale EN. Compressive strength of amalgam triturated by a high-speed amalgamator and by an ultrahigh-speed mixer. The Journal of prosthetic dentistry. 1968 Jun 1;19(6):598-604.

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POTENTIAL HEALTH AND ENVIRONMENTAL ISSUES OF MERCURY-
CONTAMINATED AMALGAMATORS
The authors assessed used amalgamators and evaluated the potential mercury vapor health
risk, using established Occupational Safety and Health methods and American Conference of
Governmental Industrial Hygienists standards.
Ten of the 11 amalgamators assessed had measurable mercury vapor levels. Four
amalgamators were found to have internal static mercury vapor levels above Occupational
Safety and Health Administration ceiling limit thresholds.
Conclusion: Amalgamators may be contaminated internally with metallic mercury. Although
the authors detected mercury vapor from these units during aggressive, simulated clinical use,
dilution factors combined with room air exchange were found to keep health risks below
established federal safety thresholds.
Roberts HW, Leonard D, Osborne J. Potential health and environmental issues of mercury-contaminated amalgamators. The Journal of the American Dental Association. 2001 Jan 1;132(1):58-64.

36
MULLING
Mulling is a continuation of trituration.
 Improve the homogeneity of the mass
 To assure a consistent mix. It can be accomplished in two ways:
1. The mix is enveloped in a dry piece of rubber dam and vigorously rubbed between the
first finger and thumb; or the thumb of one hand and palm of another hand. The
process should not exceed 2 to 5 seconds.
2. After trituration the pestle can be removed from the capsule, and the mix triturated in
the pestle-free capsule for additional 2 to 3 seconds. This will also assure cleaning of
the capsule walls of remnants of the amalgam mix, thereby delivering the mix in one
single, coherent, and consistent mass.

CONSISTENCY OFMIX
37
Undertriturated Normal Overtriturated
Philips, Text book of dental materials , 12TH Edition
 Rough & grainy mix,
difficult to manipulate
 Rough surface after carving,
less resistance to tarnish &
corrosion
 Compressive & tensile
strength reduced
 Mix will harden too rapidly
& excess mercury will be left
in the restoration
• Has maximum strength.
• Appears shiny and has a
smooth surface and
consistency.
• Smooth carved surface
will retain its luster long
after polishing.
• Separates as single mass
from capsule.
• Mix will be soupy,
difficult to remove from
capsule, too plastic to
manipulate
• Working time decreased
• Creep is increased
• Increased contraction of
amalgam

CONDENSATION
38
Phillip’s Science of Dental Materials
11th edition
o The goal of condensation is to compact the alloy into the prepared cavity so that the
greatest possible density is attained, with sufficient mercury present to ensure continuity
of the matrix phase (Ag2Hg3) between the remaining alloy particles.
o This results from a reduction of excess mercury and porosity within the set amalgam.
o After the mixture is made, the increments of alloy should be carried to, and inserted in, the
prepared cavity by means of instruments such as small forceps or an amalgam carrier
designed for this purpose.

OBJECTIVES
To reduce the
number of voids
To remove unreacted Hg out
of increments during
building up restoration
To adapt the plastic
amalgam mix to cavity
walls and margins.
39

40
oA well-condensed amalgam restoration can be achieved only if the mixture has a proper
consistency.
oA dry, grainy mix lacks a uniform distribution of mercury and plasticity, as described
previously, and a mix that is hard and hot to the touch has probably been mixed too long. In
either case, a new mix should be prepared.
oThe longer the time that elapses between mixing and condensation, the weaker the amalgam
will be. Condensation of partially set material fractures and breaks up the matrix that has
already formed.
oIn addition, when the alloy has lost a certain amount of plasticity, it is difficult to condense
without producing internal voids and layering.

41
Effect of elapsed time between trituration and condensation on the strength of the
hardened amalgam. The greater the elapsed time, the lower is the strength

42
HAND CONDENSATION
Once the increment of amalgam is inserted into the cavity, it should immediately be
condensed with sufficient pressure to remove voids and to adapt the material to the walls.
The initial condenser should be small enough to condense amalgam into the line angles.
When the first portion has been condensed, the successive portions of the divided
amalgam are added after first squeezing the excess mercury away.
Successive portions require more force to squeeze away mercury, because more free
mercury is reacting with the alloy particles.

43
Condensation is usually started at the center and then the condenser point is
stepped little by little towards the cavity walls.
Care should be taken when condensing with hand
instruments to use points that are shaped approximately to
the outline of the area being restored.
 Spheroiding’ of amalgam at the internal line angles
which result if inadequately designed instruments are
used

44
After condensation of an increment, the surface should be shiny in appearance. This
indicates that there is sufficient mercury present at the surface to diffuse into the next
increment so that each increment, as it is added, bonds to the preceding one.
This is done until the cavity is overfilled by around 1mm.Any mercury rich material at
the surface, is removed when the restoration is carved.
If the cavity is larger and extra time is required for condensation, another mix should be
made just before the original one loses its plasticity.

45
• After completely filling the cavity, an over dried amalgam mix is condensed
heavily over the restoration using the largest condensers possible for the involved
tooth. This mix is called the blotting mix.
This serves to :
• Blot excess mercury from the critical marginal and surface area of the
restoration and
• To adapt amalgam more intimately to the cavosurface anatomy.

• A small condenser(0.8mm) is used at the initial stages of condensation to
pack into retentive grooves and cavo surface margins.
• Medium sized condensers should be used to pack the bulk of the restoration.
• Large size is used for the last portion of the occlusal surface.
46

MECHANICAL CONDENSORS
ULTRASONIC CONDENSORS
•Not recommended because of increased mercury
levels in dental office.
• Use rapid vibration
• Used where high condensation forces
are required.
47

48
Mechanical Condensation:
-Condensation of the amalgam is performed by an automatic device.
-Useful for irregular shaped alloys when high force is used.
- two types: Mallet type and vibrating type.
Advantages are:
a) less energy is needed than for hand condensation.
b) operation may cause less fatigue to the dentist.
Dentatus amalgam condenser (vibrating type)

CONDENSATION PRESSURE
o The area of the condenser tip and the force exerted on it by the
operator govern the condensation pressure (force per unit area). When
a given force is applied, the smaller the condenser, the greater is the
pressure exerted on the amalgam.
o If the condenser point is too large, the operator cannot generate
sufficient pressure to condense the amalgam adequately and force it
into retentive areas.
o Studies have shown that force in the range of 13.3-17.8 N(3-4 lb) represent the
average force employed.
49

THE INFLUENCE OF PRECONDENSATION MERCURY CONTENT
AND MULLING ON THE TRANSVERSE STRENGTH OF
AMALGAMS CONDENSED AFTER A DELAY
• The purpose of this study was to investigate the influence of changing initial mercury
content on the final strength of amalgams and the effect of transverse strength of mulling
the amalgam when the condensation was delayed for five minutes.
• The five minutes delay of the condensation reduced the strength of the amalgams by 1 to
42% depending on the brand of alloy and inital mercury content. Increasing the inital
mercury content reduced the effect of the delay on the final strength. The mulling of the
amalgam mix also decreased the effect of the delay.
• It was concluded that a moderate excess of initial mercury gives the dentist a longer
condensing time thus allowing him to perform the condensing procedure with care.
50
Forsten L. The Influence of Precondensation Mercury Content and Mulling on the Transverse Strength of Amalgams Condensed After a Delay. Acta Odontologica Scandinavica. 1972 Jan 1;30(4):453-61.

PRE CARVE BURNISHING
51
Materials used in dentistry – S Mahalaxmi
o Burnishing is defined as the plastic deformation of a surface due to
rubbing/sliding contact with another object. In dental restorations, burnishing is
done to improve the surface characteristics of a restoration.
o Immediately after condensation, a large, round burnisher is used in light strokes
from the restoration toward the cavosurface margin. This is known as pre-
carve burnishing. It is considered to be a continuation of the condensation
procedure. Beaver tail burnisher is used in inaccessible areas such as proximal
surfaces of the restoration.

52
THE OBJECTIVES OF PRE-CARVE BURNISHING
1. To improve the marginal adaptation of the amalgam
2. To further reduce the size and number of voids present on the surface of the
restoration
3. To bring any further excess mercury to the surface, which can be removed during
carving
4. To condition the amalgam surface to the carving procedure
Materials used in dentistry – S Mahalaxmi

53
o After the amalgam has been condensed into the prepared cavity, it is carved to
reproduce the proper tooth anatomy.
o The objective of carving is to simulate the anatomy rather than to reproduce extremely
fine details. If the carving is too deep, the bulk of amalgam may become too thin and it
may fracture under direct occlusal loading.
CARVING

To produce a restoration with no underhangs, ie., all
marginal details of the cavity preparation are completely
covered with amalgam.
To produce a restoration with the proper physiological
contours.
.
To produce a restoration with functional, non
interfering Occlusal anatomy.
54
To produce a restoration with minimal flash
Silver Amalgam in Clinical Practice: by I.D.Gainsford
OBJECTIVES

57
To produce a restoration with adequate, compatible
marginal ridges.
To produce a restoration with the proper size, location,
extent and interrelationship of contact areas.
.
To produce a restoration not interfering in any way
with the integrity of the periodontium, enhancing its
health and amenable for plaque control.
To produce a restoration with physiological
compatible embrasures.

58
A scraping or ringing sound should be heard when it is carved(amalgam cry).
After carving, the outline of the amalgam margin should reflect the contour and location of the
prepared cavosurface margin.
An amalgam restoration that is more than minimally overcarved (a submarginal defect >
0.2mm) should be replaced.

To remove scratches and
irregularities on the amalgam surface
POST CARVE BURNISHING
60
Final smoothening can be concluded by rubbing the surface
with a moist cotton pellet or by lightly smoothing the surface
with a rubber polishing cup and an extremely fine polishing
or prophylaxis paste
Burnishing of the occlusal anatomy can be
accomplished with a ball burnisher with gentle
strokes from the amalgam to the tooth surface.
After carving is completed the surface of the restoration should be smoothened. This may be
accomplished by burnishing the surface and margins of the restoration lightly to produce a
smooth and satin appearance.

61
• Clinical data on performance of restorations support the desirability of burnishing the fast
setting, high-copper systems. Burnishing slow-setting alloys can damage the margins of
the restoration.
Undue pressure should not be exerted in burnishing and heat generation should be
avoided. Temperatures above 60°C (140°F) cause a significant release of mercury.

oRegardless of alloy, trituration method or condensation technique, the carved surface of
the filling is rough, or covered with scratches, pits, and irregularities, which can result in
concentration cell corrosion over time.
oThe smooth surface on the restorations is produced by the final finishing procedure.
oThe final finishing of the restoration should be delayed until the amalgam develops
sufficient strength to resist the pressure of polishing.
oGenerally, the recommendation is to wait for at least 24 h or until the next appointment.
62

63
Influence of burnishing on amalgam adaptation to cavity walls
CONCLUSIONS
 By comparing the two images, it can be seen that the burnished amalgam has better
adaptation than the unburnished amalgam. This study indicated that burnishing during
condensation improves amalgam adaptation.
 High-copper alloys provided better adaptation than the conventional fine cut alloy.
Spherical high-copper alloy tested better than conventional high-copper alloy.
 Three alloys were used in the study (New True Dentalloy, a conventional fine cut alloy,
Novaloy, a conventional high-copper alloy and Sybraloy, a spherical high-copper alloy).
The alloy was triturated for 10 seconds in a mechanical amalgamator with the use of a
plastic capsule and metal pestle.
 The amalgam condensation was made by two methods: with burnishing and without
burnishing. Black and white photographs of each specimen at a magnification of X500
were made
Lovadino JR, Ruhnke LA, Consani S. Influence of burnishing on amalgam adaptation to cavity walls. J Prosthet Dent. 1987 Sep 1;58(3):284.

64
FINISHING AND POLISHING
Finishing: Removes the surface irregularities
Polishing: The process that removes the scratches & irregularities from the surface of the
restoration leaving a smooth , highly glazed surface that is corrosion resistant.
Finishing and polishing are necessary to:
1.Complete the carving
2.Refine the anatomy, contours and marginal integrity.
3.Enhance the surface texture of the restoration.
Final finishing is done to remove superficial scratches, pits & irregularities. This in turn
minimizes corrosion & prevents adherence of plaque.

Removal of gross overhangs and
flashes
Finishing Burs
Removal of unwanted shiny
contacts
• Finer finishing
burs and disc
Removal of Superficial
scratches and irregularities
Finer Rubber
cups
FINISHING
65

Finishing strips for
proximal surfaces
POLISHING
• Rubber cup
with flour of
pumice
66

67
• The area may be further smoothened using light pressure with a suitably shaped
round finishing bur. This bur removes the scratches from the green or white
stone.
• Polishing is initiated with coarse abrasive rubber point at slow speed and an
air water spray.
• Final polishing may be accomplished by using a rubber cup with a flour of
pumice or tin oxide followed by a high luster agent like precipitated chalk.
• Additional finishing and polishing procedures are not attempted within 24
hours of insertion because crystallization is incomplete.

ADVANTAGES
Ease of handling
High compressive strength
Excellent wear resistance
Favourable long term clinical results
Optimal dimensional changes
Sealing ability improves with age by
formation of corrosion products at tooth
amalgam interface.
Relatively not technique sensitive
DISADVANTAGES
Non esthetic
Less conservative in removal of tooth
structure
More difficult tooth preparation
Initial marginal leakage
Does not bond to the tooth structure
Amalgam is a good thermal conductor-thus
base is required.
Less tensile strength
Galvanic currents produced in certain cases.
68
ADVANTAGES AND DISADVANTAGES OF
SILVER AMALGAM

INDICATIONS AND CONTRAINDICATIONS
OF AMALGAM RESTORATIONS
INDICATIONS
1. For permanently restoring class I,
II, and V restorations (where
esthetics is not a concern)
2. Core build-up material
3. Complex amalgam restorations
4. For preparation of dyes
5. As a retrograde filling material
(not used nowadays)
6. Post endodontic access filling
CONTRAINDICATIONS
1. Anterior teeth where aesthetics is
prime concern
2. Aesthetically prominent areas of
posterior teeth.
3. Small to Moderate class I and II
restoration that can be well isolated.
4. Small class IV defects.
69

70
MERCURY MANAGEMENT
Crucial that the alloying reaction of mercury with the Ag-Sn alloy is complete. after
completion only extremely minute levels of mercury can be released.
Mackert et al and Mandel scientifically refuted the problems caused by mercury
hypersensitivity. It is a mild reaction and not life threatening.
In 1991,the National institute of health-National institute for dental research, the FDA
and several scientists and clinicians concluded that there was no basis for claims that
amalgam was a significant health hazard.

71
Historically the source of mercury contamination was spillage of liquid mercury as it
was dispensed in bottles which was transferred to dispensers and then to individual
capsules for mixing.
Mishandling at any stage could result in splashing of mercury and its scattering
widely as small droplets.
Current use of encapsulated amalgam has eliminated most chances of spillage.
The critical time is when the metallic mercury is in the vapors form, it can be inhaled
and absorbed through the alveoli in the lungs at 80% efficiency. Thus inhalation is
the major route of entry in the human body.

72
MERCURY THERMOMETER POTRAYING DIFFERENT LEVELS OF MERCURY TOXICITY –
ASSESSED BY URINARY MERCURY CONCENTRATION
(as micrograms of mercury per gram of creatinine)
Materials used in dentistry S.Mahalaxmi

73
Mercurialism (Hydragyrism):
If exposed to above threshold values of mercury vapour for a long time, this may be
seen. Features include:
Drowsiness, headache, loss of concentration, tremors in hands, lips, tongue, kidney
failure, stomatitis, gingivitis and increased salivation, ulcerations and even
loosening of teeth. (Shaefer)
Amalgam illness – term given to the condition, usually self reported, that is
attributed patients to mercury vapour intake from their existing amalgam
restorations.
symptoms- fatigue, difficulty in concentrating, muscular pain and immunologic
disorders.
Bates MN. Dental amalgam fillings: An under-investigated source of mercury exposure. 2019.

74
In the dental office, the sources of mercury exposure related to amalgam include:
(1)Amalgam raw materials being stored for use
(2)Mixed but unhardened amalgam during trituration, insertion and intraoral hardening.
(3)Amalgam scrap that has insufficient alloy to consume the mercury present completely.
(4)Amalgam undergoing finishing and polishing operations.
(5)Amalgam restorations being removed.

75
During triturition, small local spills are best collected with a vacuum aspirator.
When small droplets of mercury rich material contaminate the floor coverings, the
only practical approach to decontaminate the area is to replace the coverings. There
is no effective treatment for removing liquid mercury from carpeting.
Mouth masks do not filter mercury vapour from air. Routine exposures are monitored
with exposure badges(dosimeters).
During intraoral condensation some mercury vapour is released. To control this a
rubber dam and high volume evacuation should be used.

76
Scrap amalgam from condensation procedures should be collected and stored under
water, glycerin or spent x-ray filter(source of sulfide and silver ions for it to react and
form a solid product) in a tightly capped jar.
Melting of the Ag-Hg phase also occurs during amalgam removal since the surface
temperature increases several hundred degrees when the high speed bur contacts the tooth
structure. Thus mercury is vaporized. Rubber dam, high volume evacuation and water
cooling is used to control the situation.

77
ADA RECOMMENDATIONS FOR DENTAL MERCURY HYGEINE
1) Train all personnel regarding mercury handling and hazards.
2) Make them aware of the potential sources of mercury vapour in the operatory.
3) Work in well ventilated spaces with an exhaust.
4) Monitor the dental operatory atmosphere for mercury vapour. Current limit for mercury
vapour is 50 microgram/m3 in any 8 hr work shift over a 40 hr week.
5) Floor covering should be non absorbent, seamless and easy to clean.
6) Use precapsulated alloys.
7) Use amalgamator with completely enclosed arm.
8) Avoid skin contact with mercury or freshly prepared amalgam.
9) Re-cap single use capsules after use if possible.
Sturdevant; 5th Edition

78
10) Use high volume evacuation while finishing or removing amalgam.
11) Salvage and store all scrap amalgam.
12) Dispose amalgam scrap and mercury contaminated items as per applicable
regulations.
13) Clean up spilled mercury using trap bottles, tape or freshly mixed amalgam.
14) Remove professional clothing before leaving the workplace.
Sturdevant; 5th Edition

CLINICAL LONGEVITY
79
Corbin SB, Kohn WG. The benefits and risks of dental amalgam: current findings reviewed. Journal of the American Dental Association (1939). 1994 Apr 1;125(4):381-8.

80
CLINICAL LONGEVITY
Silver amalgam continues to be the most widely used permanent restorative
material for posterior teeth. However, the clinical success of amalgam
restoration depends upon the proper cavity design and correct manipulation of
the alloy.
It is determined by monitoring many restorations through a longitudinal clinical
research study or a cross sectional clinical study.
Clinical failure is the point at which the restoration was no longer serviceable or at
which time the restoration poses other severe risks if it is not replaced.
The average replacement age of conventional low Copper amalgam in clinical practice
is 5-8 yrs. High Cu amalgams have a highest survival rate of 85%.
Advances in operative dentistry; by – Narin, Jean

81
Amalgam restoration related failures include:
1.Bulk fracture of the restoration.
2.Corossion and excessive marginal fracture.
3.Sensitivity or pain.
4.Secondary caries.
5.Fracture of tooth structure forming the restorative tooth preparation wall.
• Annual failure rates range between 0% to 7% for Non gamma-2 and gamma-2
containing alloys with observation periods of upto 20 years.
• Clinical diagnosis of secondary caries was recorded to be the main reason for
the failure of amalgam restorations.
Advances in operative dentistry; by – Narin, Jean

82
REPAIR
A failing amalgam restoration should be repaired rather than replaced. Every time an
amalgam restoration is replaced, the cavity outline is increased by at least 0.5mm
leading to larger restoration and weaker tooth.
For repairing, new amalgam is condensed to the already failing material. The bond
between the old and new amalgam is the main source of structural weakness of the
repaired restoration.
Factors such as contamination with saliva and oxidization of the fractured surface of
the old amalgam restoration prevent an effective bond between the old and new
amalgam.
Jorgensen and Saito(1968) were able to obtain an increased bond strength by rubbing
the surface of the old restoration with the condenser in the presence of mercury.
However, this technique is not reliable under oral conditions.
Jessup JP, Vandewalle KS, Hermesch CB, Buikema DJ. Effects of surface treatments on amalgam repair. Operative dentistry. 1998 Jan 1;23:15-20.

Amalgam Repair: Quantitative Evaluation of Amalgam-resin and
Resin-tooth Interfaces with Different Surface Treatments
Çehreli SB, Arhun N, Celik C.
• Repairing defective amalgam restorations with resin composite offers a minimally
invasive solution compared to replacement; etch & rinse adhesive systems are suggested
to reduce microleakage.
• This in vitro study evaluated the effect of different adhesive systems and surface
treatments on the integrity of amalgam-resin and resin-tooth interface after partial
removal of pre-existing amalgam.
• All Bond 3 and XP bond (etch & rinse) produced the best results at each section. All the
materials exhibited more microleakage at the amalgam interface than the tooth interface.
Surface finishing with different burs did not statistically affect microleakage.
• Conclusion: In terms of microleakage reduction, etch & rinse adhesives may be preferred
over self-etch adhesives for amalgam repair.
Cehreli SB, Arhun N, Celik C. Amalgam repair: quantitative evaluation of amalgam-resin and resin-tooth interfaces with different surface treatments. Operative dentistry. 2010 May;35(3):337-44.
83

Gallium Alloys
• Introduced by Putt Kammer in1928
• Gallium alloys have been developed as an attempt to replace mercury in amalgam.
Indium and/or tin are incorporated to gallium to produce an alloy which is liquid at
room temperature. This alloy can be mixed and condensed similar to silver
amalgam.
Eg- Gallium Alloy GF
- Gallium Alloy GF II
- Galloy
85
ALLOY LIQUID
Silver (Ag) – 60% Gallium (Ga) - 62%
Tin (Sn) -25% Indium (In) - 25%
Copper (Cu) -13% Tin (Sn) -13%
Palladium ( Pd) - 2%
Bharti R, Wadhwani KK, Tikku AP, Chandra A. Dental amalgam: An update. Journal of conservative dentistry: JCD. 2010 Oct;13(4):204.

PROPERTIES:
Compressive strength: 350 MPa
(High Copper silver alloy – 370 MPa )
Creep - 0.09+0.03%
(High Copper silver alloy – 0.04 + 0.13%)
Tensile strength is higher.
Manipulation of these alloys are difficult. Since these alloys are sticky, their condensation
into the cavity is time consuming.
86

Drawbacks
Corrosion of gallium alloy is high.
Surface roughness, marginal discoloration and fracture were reported.
Setting expansion is very high.
(hydrophobic resin coating has to be applied above and below the
restoration)
Technique sensitive.
Expensive.
87

A comparison of the mechanical properties of a gallium-
based alloy with a spherical high-copper amalgam
The aim of the present study was to investigate how the mechanical properties of
a palladium free gallium-based alloy (Galloy) compare with a leading spherical high-
copper Amalgam (Tytin).
Conclusion: The significant reduction in the 1 h mean compressive fracture strength and
hardness identified for Galloy compared with Tytin possibly indicate a slower setting
reaction in the gallium-based alloy.
Manual condensation of the gallium-based alloy produced specimens with inferior
mechanical properties possibly due to the increased likelihood of introducing voids within
the test specimens. Previous reports indicating poor corrosion resistance and moisture
sensitivity of gallium-based alloys. 88
Shaini FJ, Fleming GJ, Shortall AC, Marquis PM. A comparison of the mechanical properties of a gallium-based alloy with a spherical high-copper amalgam. Dental Materials. 2001 Mar 1;17(2):142-8.

FLUORIDE CONTAINING AMALGAM
 Secondary caries is one of the most important cause of failure in amalgam restoration.
 The addition of fluoride to amalgam was therefore attractive way to stimulate the
anticariogenic properties of silicate cement.
 8% Stannous fluoride
Some studies also used Stannous fluoride as cavity liner below the amalgam
restorations.
89

Results / Advantages :
 Studies showed that there was reduced solubility of enamel adjacent to fluoride
containing amalgam.
 One study has shown that there was lower incidence of secondary caries around the
fluoride containing amalgam restoration.
 Exact mechanism played in fluoride uptake in the fluoride containing amalgam
restoration is unknown.
Disadvantages :
 Invitro studies have shown that there is reduction in mechanical properties such as
compressive strength and corrosion resistance when stannous fluoride is added to the
amalgam.
Burke FM, Ray NJ, McConnell RJ. Fluoride‐containing restorative materials. International dental journal. 2006 Feb;56(1):33-43.
90

INDIUM
Indium was incorporated into the amalgam structure to minimize the vaporization of
mercury from the amalgam surface.
 Powell et al in 1989 first reported that the addition of pure indium powder to a high
copper amalgam alloy decreases mercury vaporization.
Properties :
decreases surface tension
reduces amount of mercury necessary
reduces creep and marginal breakdown
increases strength
91
Powell LV, Johnson GH, Bales DJ. Effect of admixed indium on mercury vapor release from dental amalgam. Journal of dental research. 1989 Aug;68(8):1231-3.

Advantages:
 Total reduction in the amount of mercury present.
 More efficient oxidation of the surface of mercury releasing phase.
 It is good wetting agent and adapts well to tooth surface.
 higher in compressive strength by 16%, lower in creep by 40% (0.17%) and has a
lower dimensional change on setting.
92

BONDED AMALGAM RESTORATIONS
 To overcome one of the major disadvantage of silver (it does not adhere properly to
cavity walls) adhesive systems were designed to bond amalgam to enamel and dentin.
 It also improves its adhesion, inability to strengthen remaining tooth structure and the
need for removal of healthy tooth structure for gaining retention.
 The most commonly used amalgam adhesives are based on the 4 - META system.
Various Agents are
Amalgam Bond , All Bond 2, Optibond 2 ,Panavia ,Clearfil Linear Bond 2, Scothbond MP.
93
Mahler DB, Engle JH, Simms LE, Terkla LG. One-year clinical evaluation of bonded amalgam restorations. The Journal of the American Dental Association. 1996 Mar 1;127(3):345-9.

INDICATIONS
 Conservative preparations , reinforcement of remaining tooth structure, improvement of
marginal seal.
 Boned amalgam restorations are specially indicated for extensively carious posterior.
 Bonded amalgam restorations may be used as a temporary restoration, which later
can be reduced to a core under a cast crown.
 Can be used as amalgam sealants.
94

ADVANTAGE DIS ADVANTAGE
 More conservative
 Reinforces tooth structure
 Decreases the incidence of
marginal fracture
 Provides a bond at the tooth
restoration interface
 Cost effective
 Technique sensitive
 Clinical performance are not
documented
 No sustained effects of
amalgam bonding when
subjected to thermocycling
 Hydrolytic stability of the
bond is questionable
95

CONSOLIDATED SILVER ALLOY SYSTEMS
 One amalgam substitute being tested is a consolidated silver alloy system developed at
the National Institute of Standards and Technology (Eichmiller et al., 1998).
 It uses a fluoroboric acid solution to keep the surface of the silver alloy particles clean.
 The alloy, in a spherical form, is condensed into a prepared cavity in a manner similar to
that for placing compacted gold.
 One problem associated with the insertion of this material is that the alloy strain
hardens, so it is difficult to compact it adequately to eliminate internal voids and to
achieve good adaptation to the cavity without using excessive force (Berry et al., 1998).
96
Monomers M. RECENT ADVANCES AND MODIFICATIONS OF DENTAL RESTORATIVE MATERIALS-A REVIEW.

RESIN COATED AMALGAM
 To overcome the limitation of microleakage with amalgams, a coating of unfilled resin over
the restoration margins and the adjacent enamel, after etching the enamel, has been tried.
Although the resin may eventually wear away, it delays microleakage until corrosion
products begin to fill the tooth restoration interface.
 Mertz-fairhurst and others evaluated bonded and sealed composite restorations placed
directly over frank cavitated lesions extending into dentin versus sealed conservative
amalgam restorations and conventional unsealed amalgam restorations. The results indicate
that both types of sealed restorations exhibited superior clinical performance and longevity
compared with unsealed amalgam restorations over a period of 10 years.
97

99
Bernando M, Luis H, Martin MD, et al: Survival and reasons for failure of amalgam versus composite restorations placed in a randomized clinical trial. J Am Dent Assoc 138:775–783, 2007.
 The survival rate of the amalgam restorations was 94.4 percent; that of composite
restorations was 85.5 percent.
 Annual failure rates ranged from 0.16 to 2.83 percent for amalgam restorations and from
0.94 to 9.43 percent for composite restorations. Secondary caries was the main reason for
failure in both materials. Risk of secondary caries was 3.5 times greater in the composite
group.
 Amalgam restorations performed better than did composite restorations. The difference in
performance was accentuated in large restorations and in those with more than three surfaces
involved.
 Clinical Implications. Use of amalgam appears to be preferable to use of composites in
multi-surface restorations of large posterior teeth if longevity is the primary criterion in
material selection.

Amalgam restorations do not chemically bond to the cavity walls, but allow microleakage
which is gradually reduced by corrosion products.
High copper amalgam corrodes more slowly than conventional amalgam and an
intermediary sealer such as a cavity varnish is needed.
Corrosion is also dependent on individual variations of the chemical components of oral
fluids.
The ability of the amalgam to resist corrosion affects the progress of potential secondary
caries at the restoration margin.
Ben‐Amar A, Cardash HS, Judes H. The sealing of the tooth/amalgam interface by corrosion products. Journal of Oral Rehabilitation. 1995 Feb;22(2):101-4.
100

101
CONCLUSION
 Dental amalgam remains a predictable, cost-effective, and safe means for the
restoration of posterior (and some anterior) teeth that are missing various
amounts of tooth structure.
Although the use of dental amalgams is on the decline in many
countries, the basis of any restoration is the understanding of the
underlying material science. The dentist has to weigh the advantages
over the disadvantages of any material to analyze and decide how best
to use it.This holds good for silver amalgam material and restorations
as well.

REFERENCE
• Sturdevant's art & science of operative dentistry book.
• Marzouk Operative Dentistry, Modern Theory And Practice.
• Craig's Restorative Dental Materials 13th Edition
• Anusavice-K.J. Phillip’s Science Of Dental Materials – 13th Edition
• Science Of Dental MaterialsAnd ClinicalApplication- V Shama BhatAnd B T Nandish- 2nd
Edition
• Materials Used In Dentistry: S.Mahalaxmi –1st Edition
• Graham BP. Advances in Operative Dentisty: Contemporary Clinical Practice. New York
State Dental Journal. 2002 Feb 1;68(2):60.
• Mahler DB: he high-copper dental amalgam alloys. J Dent Res 76:537–541, 1997. 17.
• Suchatlampong C, Goto S, Ogura H: Early compressive strength and phase-formation of
dental amalgam. Dent Mater 14:143–151, 1995.
• Burke FM, Ray NJ, McConnell RJ. Fluoride‐containing restorative materials. International
dental journal. 2006 Feb;56(1):33-43. 102

• Bhattacharya A, Vaidya S, Tomer AK, Raina A. GIC at It’s best–A review on ceramic
reinforced GIC. International Journal of Applied Dental Sciences. 2017;3(4):405-8.
• Bernando M, Luis H, Martin MD, et al: Survival and reasons for failure of amalgam versus
composite restorations placed in a randomized clinical trial. J Am Dent Assoc 138:775–783,
2007.
• Corbin SB, Kohn WG. The benefits and risks of dental amalgam: current findings reviewed.
Journal of the American Dental Association (1939). 1994 Apr 1;125(4):381-8.
• Jessup JP, Vandewalle KS, Hermesch CB, Buikema DJ. Effects of surface treatments on
amalgam repair. Operative dentistry. 1998 Jan 1;23:15-20.
• Çehreli SB, Arhun N, Celik C. Amalgam repair: quantitative evaluation of amalgam-resin and
resin-tooth interfaces with different surface treatments. Operative dentistry. 2010
May;35(3):337-44.
• Ben‐Amar A, Cardash HS, Judes H. The sealing of the tooth/amalgam interface by corrosion
products. Journal of Oral Rehabilitation. 1995 Feb;22(2):101-4.
• Mahler DB, Engle JH, Simms LE, Terkla LG. One-year clinical evaluation of bonded
amalgam restorations. The Journal of the American Dental Association. 1996 Mar
1;127(3):345-9. 103

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