Dental amalgam is a dental filling material composed of a mixture of metals including liquid mercury and a powdered alloy of silver, tin, and copper. Approximately half of dental amalgam is mercury by weight. Mercury binds the alloy particles together to form a strong, durable filling. While dental amalgam has been used widely for over 150 years, it also has some disadvantages such as its gray color, potential toxicity from mercury, and lack of bonding to tooth structure. Liners and bases are often used under amalgam fillings to reduce post-operative sensitivity and act as a protective buffer layer.

1. DENTAL
AMALGAM

2. WHAT IS DENTAL AMALGAM?
Dental amalgam is a dental filling material used to
fill cavities caused by tooth decay. It has been used
for more than 150 years in hundreds of millions of
patients around the world.
Dental amalgam is a mixture of metals, consisting of
liquid (elemental) mercury and a powdered alloy
composed of silver, tin, and copper. Approximately
50% of dental amalgam is elemental mercury by
weight. The chemical properties of elemental
mercury allow it to react with and bind together the
silver/copper/tin alloy particles to form an amalgam.
Dental amalgam fillings are also known as “silver
fillings” because of their silver-like appearance.
Despite the name, "silver fillings" do contain
elemental mercury.

3. COMPOSITION
• Dental amalgam is produced by mixing liquid mercury with an alloy made of silver, tin, and copper
solid particles.
• Small quantities of zinc, mercury and other metals may be present in some alloys.
• This combination of solid particles is known as amalgam alloy.
• The composition of the alloy particles are controlled by the ISO Standard for dental amalgam alloy in
order to control properties of set amalgam such as corrosion and setting expansion. It is important to
differentiate between dental amalgam and the amalgam alloy that is commercially produced and
marketed as small filings, spheroid particles, or a combination of these, suitable for mixing with liquid
mercury to produce the dental amalgam.
• Amalgam is used most commonly for direct, permanent, posterior restorations and for large
foundation restorations, or cores, which are precursors to placing crowns.
• The reaction between mercury and alloy when mixed together is termed an amalgamation reaction. It
will result in the formation of a silver-grey workable mass which can be condensed into cavities. After
condensing, the dental amalgam is carved to generate the required anatomical features and then
hardens with time.
• Conventional amalgam alloy commonly consists of silver (~65% ), tin (~29%), copper (~8%) and other
trace metals; current amalgam alloy consists of silver (40%), tin (32%), copper (30%) and other metals.

4. WHY IS MERCURY USED IN DENTAL
AMALGAM?
Approximately half of a dental amalgam filling is liquid
mercury and the other half is a powdered alloy of
silver, tin, and copper. Mercury is used to bind the
alloy particles together into a strong, durable, and
solid filling. Mercury’s unique properties (it is a liquid
at room temperature and that bonds well with the
alloy powder) make it an important component of
dental amalgam that contributes to its durability.

5. PROPERTIES OF AMALGAM
• Plastic deformation (creep)
Creep or plastic deformation happens when subjected to intra-oral stresses such as
chewing or grinding. Creep causes the amalgam to flow and protrudes from the margin
of the cavity forming unsupported edges. ‘Ditch’ is formed around the margins of the
amalgam restoration after fracture due to amalgam creep at the occlusal margins. The γ2
phase of amalgam is primarily responsible for high values of creep.

6. PROPERTIES OF AMALGAM
• Corrosion
Corrosion occurs when an electrolytic cells of anode and cathode set up in the presence of electrolytes. The
multiphase structure of dental amalgam can contribute as an anode or cathode with saliva as electrolytes.
Corrosion may significantly affect the structure and mechanical properties of set dental amalgam. In
conventional amalgam, γ2 phase is the most reactive and readily forms an anode. It will break down releasing
corrosion products and mercury. Some of the mercury will combine rapidly with unreacted alloy and some will
be ingested. The chances of ditching are further increased. Copper-enriched amalgams contain little or no γ2
phase. The copper–tin phase, which replaces γ2 in these materials, is still the most corrosion-prone phase in the
amalgam. The corrosion however is still much lower than conventional amalgam.
In spite of that, it is thought that corrosion actually offers a clinical advantage. The corrosion products will
gather at the tooth-amalgam interface and fill the microgap (marginal gap) which helps to decrease
microleakage. Even so, there are no reports of increased marginal leakage for the copper-enriched amalgams
indicating that sufficient quantities of corrosion product are produced to seal the margins.
Microleakage is the leakage of minute amounts of fluids, debris, and microorganisms through the microscopic
space between a dental restoration and the adjacent surface of the cavity preparation. Microleakage can risk
recurrent caries.

7. PROPERTIES OF AMALGAM
• Strength
An amalgam restoration develops its strength slowly and may take up to 24 hours or
longer to reach a reasonably high value. At the time when the patient is dismissed from
the surgery, typically some 15–20 minutes after placing the filling, the amalgam is
relatively weak. Therefore, dentists need to instruct patients not to apply undue stress to
their freshly placed amalgam fillings.
In addition, amalgam restorations are brittle and susceptible to corrosion.

8. WHAT IS BIOACCUMULATION?
Bioaccumulation refers to the build-up or steadily increasing concentration of a
chemical in organs or tissues in the body. Mercury from dental amalgam and other
sources (e.g., fish) is bioaccumulative. Studies of healthy subjects with amalgam fillings
have shown that mercury from exposure to mercury vapor bioaccumulates in certain
tissues of the body including kidneys and brain. Studies have not shown that
bioaccumulation of mercury from dental amalgam results in damage to target organs.

9. WHY AMALGAM?
• In an age where aesthetics are becoming more vital, dental amalgam is inadequate
since it has a nontooth color. This limitation usually leads to the use of amalgam
fillings on mainly posterior teeth. However, in contrast to other direct restoration
methods, the cost of amalgam is significantly lower. This is beneficial in poorer
countries where people are likely to choose dental restorations, with costs being a
more crucial factor in aesthetics.
• Failure rates of amalgam are low; therefore they require replacement less often than
other restoration methods. The durability of amalgam ranges from “good to excellent,”
and this factor adds to the longevity of the dental restoration.

10. WHEN TO USE DENTAL AMALGAM
When placed correctly, dental amalgam has sufficient strength to withstand the high loads
generated during mastication. It is therefore chiefly indicated for:
• The restoration of Class I and Class II cavities, particularly those of moderate to large size
• Core build-ups: when the definitive restoration will be a cast restoration, such as a crown or
bridge retainer, as more tooth structure will need to be replaced and the tooth reinforced.
Dental amalgam is used mainly in the posterior sextants of the mouth because of its
unaesthetic appearance. However, as amalgam is not tooth coloured, the core material and
the tooth tissue can be easily identified, ensuring that the margins of the crown are placed
onto tooth tissue and not the core material.

11. Teeth 46 and 45 restored with
dental amalgam – note the non-
tooth coloured appearance of the
restoration.
Tooth 25 core restored with
amalgam. Note the contrast
between the amalgam core colour
and tooth, facilitating
identification of the margin of the
core and of the preparation placed
on tooth tissue.

12. CLASSIFICATION- MARZOUK
 According to number of alloy metals:
• Binary alloys (Silver-Tin)
• Ternary alloys (Silver-Tin-Copper)
• Quaternary alloys (Silver-Tin-Copper-Indium).

13. CLASSIFICATION
 According to whether the powder consist of unmixed or admixed alloys:
Certain amalgam powders are only made of one alloy.
Others have one or more alloys or metals physically added (blended) to the basic alloy. E.g. Adding
copper to a basic binary silver tin alloy.
 According to the shape of the powdered particles:
1. Spherical shape (smooth surfaced spheres).
2. 2. Lathe cut (Irregular ranging from spindles to shavings).
3. 3. Combination of spherical and lathe cut (admixed).
 According to Powder particle size:
1. Micro cut
2. 2. Fine cut
3. 3. Coarse cut

14. CLASSIFICATION
 According to copper content of powder:
1. Low copper content alloy - Less than 4%
2. 2. High copper content alloy - more than 10%
 According to addition of Nobel metals:
• Platinum
• Gold
• Pallidum
 According to Presence of zinc:
• Zinc containing (more than 0.01%).
• Non zinc containing (less than 0.01%).

15. CLASSIFICATION
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 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. Quatemary alloy i.e. Silver, tin, copper and indium.
• Sixth generation (consisting eutectic alloy).

16. INDICATIONS OF AMALGAM
Class I and class II cavities.-
moderate to large restorations.
As a core build up material.
Can be used for cuspal
restorations (with pins usually)
In combination with composite
resins for cavities in posterior
teeth. Resin veneer over
amalgam.
As a die a material.
Restorations that have heavy
occlusal contacts.
Restorations that cannot be well
isolated
In teeth that act as an abutment
for removable appliances
Class 3 in unaesthetic areas
eg.distal aspect of
canine.especially if
Preparation is extensive with
minimal facial involvement
Class 5 lesions in nonesthetic
areas especially when access is
limited and moisture control is
difficult and for areas that are
significantly deep gingivally.

17. CONTRAINDICATIONS OF AMALGAM
Anterior teeth where
esthetics is a prime concern
Esthetically prominent
areas of posterior teeth.
Small –to-moderate classes
I and II restorations that
can be well isolated.
Small class VI restorations

18. ADVANTAGES
Ease of use, Easy to
manipulate
Relatively inexpensive Excellent wear resistance
Restoration is completed
within one sitting without
requiring much chair side
time.
Well condensed and
triturated amalgam has
good compressive
strength.
Sealing ability improves
with age by formation of
corrosion products at tooth
amalgam interface.
Relatively not technique
sensitive.
Bonded amalgams have
“bonding benefits”.
Less microleakage
Slightly increased strength
of remaining tooth
structure.
Minimal postoperative
sensitivity.

19. ADVANTAGES
Disadvantages
Unnatural appearance
(non esthetic)
Tarnish and corrosion
Metallic taste and
galvanic shock
Discoloration of tooth
structure
Lack of chemical or
mechanical adhesion
to the tooth structure.
Mercury toxicity
Promotes plaque
adhesion
Delayed expansion
Weakens tooth
structure (unless
bonded).

20. ROLE OF INDIVIDUAL COMPONENT
Silver:
• Constitutes approximately 2/3rd of conventional amalgam alloy.
• Contributes to strength of finished amalgam restoration.
• Decreases flow and creep of amalgam.
• Increases expansion on setting and offers resistance to tarnish.
• To some extent it regulates the setting time.
Tin:
• Second largest component and contributes ¼th of amalgam alloy.
• Readily combines with mercury to form gama-2 phase, which is the weakest phase and
contributes to failure of amalgam restoration.
• Reduce the expansion but at the same time decreases the strength of amalgam.
• Increase the flow.
• Controls the reaction between silver and mercury.
• Tin reduces both the rate of the reaction and the expansion to optimal values.

21. ROLE OF INDIVIDUAL COMPONENT
Copper:
• Contributes mainly hardness and strength.
• Tends to decrease the flow and increases the setting expansion
Zinc:
• Acts as Scavenger of foreign substances such as oxides.
• Helps in decreasing marginal failure.
• The most serious problem with zinc is delayed expansion, because of which zinc free
alloys are preferred now a days. Indium/Palladium: They help to increase the plasticity
and the resistance to deformation.

22. STAGES AND STEPS IN CAVITY
PREPARATION
Initial cavity preparation stage:
1. Outline form and initial depth placing the cavity margin in the final
preparation form
2. 2. Primary resistance form withstand of cavity walls and restorations
occlusal forces without fracture
3. 3. Primary retention form the shape to resist displacement through
tipping and lifting forces
4. 4. Convenience form Observation, accessability, prep, restoration

23. STAGES AND STEPS IN CAVITY
PREPARATION
Final cavity preparation stage
5. Removal of carious dentin and …..
6. Pulp protection
7. Secondary resistance and retention forms
8. Finishing external walls
9. Cleaning
1.Slightly rounded configuration
2. Convergence occlusally of vestibular and oral walls
3. Gingival wall is min 1.2mm wide
4. Occlusal width and depth of the restauration 1.5-2 mm
5. Gingival extension
6. Margin of the cavity cca 90o
7. V-shaped side-fissure

24. TRITURATION
The objective of trituration is to provide proper amalgamation of the mercury and the alloy. The alloy particles are coated with
a film of oxide which is removed by abrasion when alloy particles and mercury are triturated
Hand mixing:
•A glass mortar and pestle are used.
• The mortar has its inner surface roughened to increase the friction .
• Usually a period of 25 to 45 second is sufficient for hand mixing
Mechanical trituration:
• The disposable capsule serves as a mortar and the cylindrical metal placed in the capsule serves as the pestle.
• The alloy and mercury are dispensed into the capsule ,it is secured in the machine and the machine is turned on.
• There is an automatic timer for controlling the mixing time.
Modern amalgamator has two or more operating speeds.
The mulling process generally causes the mix to cohere so that it can be readily removed from the capsule.
Spherical alloy require less amalgamation time than lathe-cut alloys, amalgamation time also depends on the quantity.
For a given alloy/mercury ratio increased trituration time and speed shortens the working and setting time. Amalgamat or

26. RESTAURATION WITH AMALGAM
Preparation
of the cavity
Isolation
Matrices and
matrix
retainer
Wedge
placement
Trituration
Insertion,
condensation
Carving,
burnishing
Finishing,
polishing

27. PLACING OF AN AMALGAM FILLING
• By amalgam gun

28. CONDENSATION
The goal of condensation is to compact
the alloy into the prepared cavity so that
the with sufficient mercury present to
ensure complete continuity of the matrix
phase between the remaining alloy
particles.
After the mix is made condensation of
the amalgam should be promplty
initiated, condensation of partially set
material probably fractures and break up
the matrix that has already formed.
Condensation should be as rapid as
possible and a fresh mix of amalgam
should be made if condensation takes
longer than 3-4 mins.
The field of operation should be dry
before application.

29. HAND CONDENSATION
Once the increment of amalgam is inserted
into the cavity preparation it should be
condensed with pressure to avoid voids
and to adapt the material to the walls, the
condenser point is forced into the
amalgam mass under hand pressure.
Condensation is started at the center and
then condenser point is stepped little by
little towards the cavity wall.
After condensation of the each increment
excess mercury should left over the first
increment so that it can bond with the next
increment.
The procedure of adding an
increment,condensing it,adding another
increment and so forth is continued until
the cavity is overfillled.
In case the cavity is large well condensed
amalgam restoration can be achieved when
the mix has proper consistency.

30. LINERS AND BASES
Dental amalgam does not by itself bond to tooth structure.
The placement of amalgam restorations can potentially cause sensitivity post-
operatively.
According to R. Weiner, a protective layer or liner should be placed prior to the
placement of amalgam to act as a buffer, helping to reduce sensitivity to the tooth.
There are different liners that can be used in dental practices today, many of which
contain zinc. Examples of lining materials include zinc oxide eugenol, zinc phosphate,
glass ionomer cement, zinc poly-carboxylate and resin.

31. SPEED OF PLACEMENT
• Once amalgam is triturated, phase formation commences and the setting reaction is
underway.
• Amalgam must be placed in a plastic state
• Amalgam should not be placed more than 3 minutes after the start of mixing.
Attempting to condense a partly set amalgam into a cavity will result in
Poor adaptation,
Reduced marginal seal and
A weak restoration.

32. BURNISHING
First Burnish (Pre-carve Burnish)
• Carried out using a large burnisher for 15 seconds
• Use light force and move from the center of the restoration outwards to the margins.
Objectives of precarve burnishing :
• Continuation of condensation, further reduce the size and number of voids on the
critical surface and marginal area of the amalgam.
• Brings any excess mercury to the surface, to be discarded during carving.
• Adapt the amalgam further to cavosurface anatomy.

33. CARVING
Using remaining enamel as a
guide, carve gently from enamel
towards the center and recreate
the lost anatomy of the tooth.
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.

34. OBJECTIVES OF CARVING
To produce :
• A restoration with no underhangs
• A restoration with the proper physiological contours.
• A restoration with minimal flash.
• A restoration with adequate, compatible marginal ridges.
• A restoration with proper size, location, extend and interrelationship of contact areas.

35. FINAL BURNISH (POST CARVE
BURNISHING)
Following carving, check the
occlusion and carry out a brief
final burnish.
Use a large burnisher at a low
load and burnish outwards
towards the margins
Improves smoothness
Heat generation should be
avoided If temp raises above 60C,
causes release of mercury
accelerates corrosion & fracture
at margins

36. FINISHING & POLISHING
Finishing can be defined as the
process, which continues the
carving objectives, removes 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.
Can be done using descending
grade abrasive, eg. rubber
mounted stone or rubber cups.
A metallic lusture, is always done
with a polishing agent
(precipitated chalk, tin or zinc
oxide).

37. OBJECTIVE OF FINISHING AND
POLISHING
Removal of superficial scratches and irregularities Advantages:
Minimizes fatigue failure of the amalgam under the cyclic loading of mastication
Minimizes concentration cell corrosion which could begin in the surface irregularities
Prevents the adherence of plaque

38. POLISHING!
Usually, 24 hours should pass after amalgam insertion before
any finishing and polishing commences.
However, some new alloys can be polished after 8-12 hours
still others require only a 30-minute wait after insertion.

39. WHAT IS GALVANIC SHOCK?
Have you ever experienced a zinging sensation in filled teeth when you bite down? If so, you may be
experiencing galvanic shock. This term refers to the electrochemical reaction between two dental
restorations made from different materials.
Why It Happens?
Galvanic shock doesn’t occur very often, these days. It usually results when people have metal fillings
done by different dentists who may have used materials that differed a bit. If these fillings came in
contact with each other, they could send a bit of a “zap” through the tooth and other soft tissues.
Most people who still suffer from this rare chemical interaction do so because they’ve got a bunch of old
fillings in their mouth. You’re not likely to start experiencing galvanic shock after a dental visit these days.
How To Avoid Galvanic Shock?
The majority of today’s fillings are made from combinations of glass and plastic, making them charge-
free, sparing you the zing of metal ones.
If you do have old metal fillings that are bothering you, dentist can swap them out for fresh white ones
with no trouble.

40. SOURCES
• https://en.wikipedia.org/wiki/Amalgam_(dentistry)#Amalgam's_setting_reaction
• https://www.fda.gov/medical-devices/dental-amalgam/about-dental-amalgam-
fillings#benefits
• https://www.sciencedirect.com/topics/materials-science/dental-amalgams
• https://pocketdentistry.com/6-dental-amalgam/
• https://ec.europa.eu/health/scientific_committees/opinions_layman/en/dental-amalgam/l-
3/2-amalgam-preparation.htm
• https://en.wikipedia.org/wiki/Dental_restoration#Amalgam
• http://www.med-college.de/en/master_program/seminarraum/print.php?id=317&lan=2

41. THANK YOU!