SlideShare a Scribd company logo
1 of 152
Download to read offline
Presentation by:
Dr. Piyush Verma
Dept of Pedodontics & Preventive
Dentistry
Index
 Introduction
 History
 Classification
 Indications & contraindications
 Advantages/disadvantages
 Composition of amalgam & Amalgamation reactions
 Manufacturing process
 Properties of amalgam
 Manipulation of amalgam
Index
 Mercury toxicity & various health hazards
 Recent advances
 Repair of amalgam restorations
 Clinical considerations
 Amalgam wars
 Conclusion
Introduction
 Dental amalgam is an alloy made by mixing mercury
with a silver tin alloy. Dental amalgam alloy is a silver
tin alloy to which varying amount of copper and small
amount of zinc has been added.
 According to Skinner’s, amalgam is a special type of
alloy in which one of its constituent is mercury. In
dentistry, it is common to use the term amalgam to
mean dental amalgam.
History
 Amalgam -- First used by Chinese. There is a mention
of silver mercury paste by Sukung (659AD)
in the Chinese medic
 1578-lshitichen used 100 parts if Hg, 45 parts of Ag
and 100 parts of Sn
 Liu Wen-Thai (1508) and Li Shih-Chen (1578)
discussed its formulation; 100 parts of mercury to 45
parts of silver and 900 parts of tin, trituration of these
ingredients produced a paste said to be as solid as
silver.
.
 Introduced in 1800’s in France alloy of bismuth, lead,
tin and mercury plasticized at 100ºC poured directly
into cavity
 1819, Bell advocated the use of a room temperature
mixed amalgam as a restorative material, in England
 1826, M.Traveau is credited with advocating the first
form of amalgam paste , in France.
 1833
 Crawcour brothers introduced
amalgam to US
 powdered silver coins mixed with
mercury
 expanded on setting
 1895
 To overcome expansion problems
 G.V. Black developed a formula
for modern amalgam alloy
 67% silver, 27% tin, 5% copper, 1% zinc
 Black’s formula was well accepted and not much
changed for nearly sixty years.(1890-1963)
 1946 - Skinner, added copper to the amalgam alloy
composition in a small amount. This served to
increase strength and decrease flow.

 Traditional or conventional amalgam alloys
predominated from 1900 to 1970.
 1960’s - conventional low-copper lathe-cut alloy
was introduced
 1962 - A spherical particle dental alloy was
introduced, by Demaree and Taylor
 The work of Innes and Youdeis (1963) has led to the
development of high copper alloys.
 Had longer working time, less dimensional change,
easy to finish, set faster, low residual mercury, low
creep & higher early strength
 Added spherical silver copper eutectic alloy(71.9wt%
Ag and 28.1wt%Cu)particles to lathe cut low copper
amalgam alloy particles.
 These alloys are called admixed alloys
 1971 – Johnson designed a spherical particle alloy
having the composition 64% Ag, 26% Sn and 10%
cu by weight, and exhibiting no Sn8Hg after
amalgamation.
 1973 - first single composition spherical alloy
named Tytin (Kerr) a ternary system
(silver/tin/copper) was discovered by Kamal Asgar
of the University of Michigan
 1980’s alloys similar to Dispersalloy and Tytin was
introduced
Classification (Marzouk)
I. According to number of alloy metals:
1. Binary alloys (Silver-Tin)
2. Ternary alloys (Silver-Tin-Copper)
3. Quaternary alloys (Silver-Tin-Copper-Indium).
II.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
 III. According to the shape of the powdered
particles.
 1. Spherical shape (smooth surfaced spheres).
 2. Lathe cut (Irregular ranging from spindles to
shavings).
 3. Combination of spherical and lathe cut (admixed).
 IV. According to Powder particle size.
 1. Micro cut
 2. Fine cut
 3. Coarse cut
 V. According to copper content of powder
 1. Low copper content alloy - Less than 4%
 2. High copper content alloy - more than 10%
 VI. According to addition of Nobel metals
 Platinum
 Gold
 Pallidum
 VII. 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).
 According to Presence of zinc.
 Zinc containing (more than 0.01%).
 Non zinc containing (less than 0.01%).
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
INDICATIONS OF AMALGAM
 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.
CONTRA INDICATIONS 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
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.
Advantages
 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.
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).
Composition of amalgam
Conventional Amalgam Alloys: (G.V. Black’s:
Silver- tin alloy or Low copper alloy).
 Low copper alloys are available as comminuted
particles (Lathe -cut and Pulverized) and spherical
particles.
Low copper composition:
 Silver : 63-70%
 Tin : 26-28%
 Copper : 2- 5%
 Zinc : 0-2%
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.
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.
HIGH COPPER AMALGAM ALLOY (COPPER
ENRICHED ALLOYS)
 To overcome the inferior properties of low copper
amalgam alloy -- shorter working time, more dimensional
change, difficult to finish, set late, high residual mercury,
high creep & lower early strength, low fracture resistant
 Youdelis and Innes in 1963 introduced high copper
content amalgam alloys. They increased the copper
content from earlier used 5% to 12%.
 Copper enriched alloys are of two types:
1) Admixed alloy powder.
2) Single composition alloy powder.
I. Admixed alloy powder:
 Also called as blended alloys.
 Contain 2 parts by weight of
conventional composition lathe cut
particles plus one part by weight of
spheres of a silver copper eutectic alloy.
 Made by mixing particles of silver and
tin with particles of silver and copper.
 The silver tin particle is usually formed
by the lathe cut method, whereas the
silver copper particle is usually spherical
in shape.
I. Admixed alloy powder:
Composition:
 Silver-69 %
 Copper-13 %
 Tin-17 %
 Zinc-1 %
I. Admixed alloy powder:
 Amalgam made from these powders are stronger than
amalgam made from lathe cut low copper alloys
because of strength of Ag-Cu eutectic alloy particles.
 Ag-Cu particles probably act as strong fillers
strengthening the amalgam matrix.
 Total copper content ranges from 9-20%.
II. Single composition alloy
(Unicomposition):
 It is so called as it contains
particles of same
composition.
 Usually spherical single
composition alloys are used.
 As lathe cut, high copper
alloys contain more than
23% copper.
II. Single composition alloy
(Unicomposition):
1. Ternary alloy in spherical form, silver 60%, tin 25%,
copper 15%.
2.Quaternary alloy in spheroidal form containing Silver:
59%, copper 13%, tin: 24%, indium 4%.
AMALGAMATION REACTION/ SETTING
REACTION
Low copper conventional amalgam alloy
 Dissolution and precipitation
 Hg dissolves Ag and Sn
from alloy
 Intermetallic compounds
formed
Ag3Sn + Hg  Ag3Sn + Ag2Hg3 + Sn8Hg
Ag-Sn Alloy
Ag-Sn
Alloy
Ag-Sn
Alloy
Mercury
(Hg)
Sn
Sn
Sn Ag
Hg Hg
Ag
Ag
 1 2
Low copper conventional amalgam alloy
 Gamma () = Ag3Sn
 unreacted alloy
 strongest phase and
corrodes the least
 forms 30% of volume
of set amalgam
Ag-Sn Alloy
Ag-Sn
Alloy
Ag-Sn
Alloy
Mercury
Ag
Sn
Sn
Sn Ag
Hg
Hg
Ag
Hg
Low copper conventional amalgam alloy
 Gamma 1 (1) = Ag2Hg3
 matrix for unreacted alloy
and 2nd strongest phase
 10 micron grains
binding gamma ()
 60% of volume
Ag-Sn Alloy
Ag-Sn
Alloy
Ag-Sn
Alloy
1
Low copper conventional amalgam alloy
 Gamma 2 (2) = Sn8Hg
 weakest and softest phase
 corrodes fast, voids form
 corrosion yields Hg which
reacts with more gamma ()
 10% of volume
 volume decreases with time
due to corrosion
2
Ag-Sn Alloy
Ag-Sn
Alloy
Ag-Sn
Alloy
Admixed High-Copper Alloys
Initial reaction
Ag3Sn + Ag-Cu + Hg Ag3Sn + Ag2Hg3 + Sn8Hg + Ag-Cu
Ag-Sn
Alloy
Ag-Sn
Alloy
Mercury
Ag
AgAg
Sn
Sn
Ag-Cu Alloy
Ag
HgHg
  1 2
Final reaction
Ag-Cu Alloy
1
Ag-Sn
Alloy
Ag-Sn
Alloy
2 
Sn8Hg + Ag-Cu Cu6Sn5 + Ag2Hg3 + Ag-Cu
1
Single Composition
High-Copper Alloys
Ag-Sn Alloy
Ag-Sn Alloy
Ag-Sn Alloy
1

   

Ag3Sn + Cu3Sn + Hg  Ag2Hg3 + Cu6Sn5 + Ag3Sn + Cu3Sn
1
Manufacturing Process
Lathe-cut alloys
 Ag & Sn melted together
 alloy cooled
 phases solidify
 heat treat
 400 ºC for 8 hours
 grind, then mill to 25 - 50 microns
 heat treat to release stresses of grinding
Manufacturing Process
Spherical alloys
 Atomizing process produces these
different shapes.
 First liquefying the amalgam alloy, it is
sprayed through a jet nozzle under
high pressure in a cold atmosphere.
 If particles are allowed to cool before
they contact the surface of chamber,
they are spherical in shape.
 If they are allowed to cool on contact
with the surface they are flake shaped.
PROPERTIES:
ADA specification No.1 for amalgam lists following
physical properties as a measure of quality of the
amalgam.
 Creep
 Compressive strength
 Dimensional changes
 Modulus of elasticity
Strength
Compressive strength
 Amalgam is strongest in compression and weaker in
tension and shear
 The prepared cavity design and manipulation should
allow for the restoration to receive compression forces
and minimum tension and shear forces.
 The compressive strength of a satisfactory amalgam
restoration should be atleast 310 MPa.
Compressive Strengths of Low-Copper and High
Copper Amalgam
Amalgam Compressive Strength
(MPa)
1 h 7 day
Low copper 145 343
Admix 137 431
Single
Composition
262 510
Tensile strength
 Amalgam is much weaker in tension
 Tensile strengths of amalgam are only a fraction of
their compressive strengths
 Cavity design should be constructed to reduce tensile
stresses resulting from biting forces
 High early tensile strengths are important – resist
fracture by prematurely applied biting forces
Product Tensile strength (Mpa)
15min 7 days
LOW COPPER ALLOYS
a) Lathe cut
b) spherical
3.2 51
4.7 55
HIGH COPPER ALLOYS
a) Admixed
b) Unicompositional
3.0 43
8.5 56
Tensile strengths of amalgam
The factors affecting strength of amalgam are:
1) Temperature:
 Amalgam looses 15% of its strength when its
temperature is elevated from room temperature to
mouth temperature
 looses 50% of room temperature strength when
temperature is elevated to 60OC e.g. hot coffee or
soup.
2) Trituration:
 Effect of trituration on strength depends on the type
of amalgam alloy, the trituration time and the speed of
the amalgamator.
 Either, under trituration or over-trituration decreases
the strength for both traditional and high copper
amalgams.
 More the trituration energy used, more evenly
distributed are the matrix crystals over the amalgam
mix and consequently more the strength pattern in the
restoration.
 Excess trituration after formation of matrix crystals
will create cracks in the crystals, lead to drop in
strength of set amalgam
3) Mercury Content:
 Low mercury alloy content, contain
stronger alloy particles and less of the
weaker matrix phase, therefore more
strength
 Mercury is too less -- dry, granular mix,
results in a rough, pitted surface that
invites corrosion.
 If mercury content of amalgam mix is
more than 53-55%, causes drop of
compressive strength by 50%.
4) Effect of condensation:
 For lathe-cut alloys
Greater the condensation pressure, the higher the
compressive strength
Higher condensation pressure is required to minimize
porosity and to express mercury from lathe-cut
amalgam.
 For spherical alloys
Amalgams condensed with lighter pressure produce
adequate strength.
5) Effect of Porosity:
 Can be due to
 Under trituration,
Particle shape,
Insertion of too large increments into the cavity,
Delayed insertion after trituration,
 Non-plastic mass of amalgam.
 Facilitate stress concentration, propagation of cracks,
corrosion, and fatigue failure of amalgam restoration.
6) Effect of rate hardening
 Patient may be dismissed from the dental chair within 20
min, rate of hardening of the amalgam is of considerable
interset
 At the end of 20 min, compressive strength – 6% of the 1
week strength
 ADA specification stipulates minimum compressive
strength of 80 Mpa at 1 hr
 Clinical significance -- Patient should be cautioned not
to subject the restoration for high biting force for 8 hrs
after placement– 70% of its strength is gained
Modulus of elasticity
 High copper alloys tend to be stiffer than low copper
alloys
 When rate of loading increased, values of approx 62
Gpa have been obtained
Knoop Hardness
 110 kg/mm2
DIMENSIONAL CHANGES:
 When mercury is combined with amalgam it
undergoes three distinct dimensional changes.
 Stage -1: Initial contraction, occurs for about 20
minutes after beginning of trituration. Contraction
results as the alloy particles dissolve in mercury.
Contraction, which occurs, is no greater than 4.5 µcm.
 Stage -2: Expansion- this occurs due to formation and
growth of the crystal matrix around the unconsumed
alloy particles.
 Stage -3: Limited delayed contraction.
Factors that affect the dimensional changes:
1) Particle size and shape:
 More regular the particle shape, more smoother the
surface area.
 Faster and more effectively the mercury can wet the
powder particles and faster amalgamation occurs in all
stages with no apparent expansion.
2) Mercury:
 More mercury , more will be the expansion, as more
crystals will grow.
 Low mercury: alloy ratio favors contraction
3) Manipulation:
 During trituration, if more energy is used for
manipulation, the smaller the particles will become ,
mercury will be pushed between the particles,
discouraging expansion.
 More the condensation pressure used during
condensation, closer the particles are brought
together; more mercury is expressed out of mix
inducing more contraction.
Moisture contamination (Delayed Expansion):
 Certain zinc containing low copper or high copper
amalgam alloys which get contaminated by moisture
during manipulation results in delayed expansion or
secondary expansion
 Occur 3-5 days after insertion and continues for months.
 Zinc reacts with water, forming zinc oxide and hydrogen
gases.
Complications that may result due to delayed
expansion are:
 Protrusion of the entire restoration out of the cavity.
 Increased micro leakage space around the restoration.
 Restoration perforations.
 Increased flow and creep.
 Pulpal pressure pain.
Such pain may be experienced 10-12 days after the
insertion of the restoration
Flow and Creep:
 Time dependent plastic
deformation
 When a metal is placed under
stress, it will undergo plastic
deformation.
 The high copper alloys, as
compared with conventional silver
tin alloys, usually tend to have
lower creep values.
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 act as barrier to
deformation of 1 phase.
B) Manipulations:
 Greater compressive strength will minimize creep
rates.
 Low mercury: alloy ratio, greater the condensation
pressure and time of trituration, will decrease the
creep rate.
Corrosion
Excessive corrosion can
lead to:
 Increased porosity.
 Reduced marginal integrity.
 Loss of strength.
 Release of metallic products
in to the oral environment.
Phases in decreasing order of corrosion resistance
 Ag2Hg3
 Ag3Sn,
 Ag-Cu
 Cu3Sn
 Cu6Sn5
 Sn7-8Hg.
Low copper amalgam system:-
 Most corrodible phase is tin-mercury or 2 phase.
 Neither the  nor the 1 phase is corroded as easily.
 The corrosion results in the formation of tin
oxychloride, from the tin in 2 and also liberates Hg.
Sn7-8Hg + 1/202 + H2O + Cl- Sn4 (OH) 6 Cl2 + Hg
Tin oxychloride
 Reaction of the liberated mercury with unreacted 
can produce additional l and 2 (Mercuroscopic
Expansion).
 Results in porosity and lower strength.
The high copper admixed and
unicomposition alloy :-
 Do not have any 2 phase in the final set mass
 The η phase formed has better corrosion resistance.
 However,  is the least corrosion resistant phase in high
copper amalgam
 Corrosion product CuCl2.3Cu (OH)2 has been associated
with storage of amalgams in synthetic saliva.
Cu6Sn5 + 1/202 +H2O + Cl- CuCl2.3Cu (OH)2 + SnO.
Types of Corrosion:
1) Galvanic corrosion:
Dental amalgam is in direct contact
with an adjacent metallic
restoration such as gold crown
2) Crevice Corrosion:
 Local electrochemical cells may arise
whenever a portion of amalgam is
covered by plaque on soft tissue.
 The covered area has a lower oxygen
and higher hydrogen ion
concentration making it behave
anodically and corrode.
Stress Corrosion:
 Regions within the dental
amalgam that are under stress
display a greater probability for
corrosion, thus resulting in
stress corrosion.
 For occlusal dental amalgam
greatest combination of stress
and corrosion occurs along the
margins.
MANIPULATION OF DENTAL
AMALGAM
PROPORTIONS OF ALLOY TO
MERCURY
 Correct proportioning of alloy and mercury-
essential for forming a suitable mass of amalgam
 Some alloys require mercury – alloy ratios in excess
of 1:1 (Eames technique)
 whereas others use ratios of less than 1:1 with the
percentage of mercury varying from 43% to 54%.
 Automatic mechanical
dispensers for alloy & mercury
have been used in the past
 Capsules with pre proportioned
amounts of alloy & mercury
have been substituted
Cross section sketch of a disposable capsule
containing amalgam alloy & mercury
SIZE OF MIX
 Manufacturers commonly supply capsules containing
400, 600, or 800 mg of alloy and the appropriate
amount of mercury.
 For large size cavities - capsules containing 1200 mg of
all0y are also available.
TRITURATION
 Process of mixing the amalgam alloy particles with
mercury
 Originally, the alloy and mercury were mixed, and was
triturated by hand with a mortar and pestle
 Mechanical amalgamation saves time and standardizes
the procedure.
Amalgamator
Mechanical amalgamators are available in the following
speeds:
 Low speed: 32-3400 cpm.
 Medium speed: 37-3800 cpm.
 High speed: 40-4400 cpm.
 Spherical/irregular low-copper alloys – triturated at
low speed
 High copper alloys – high speed
 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: Alloy will be hot,
hard to remove from the capsule,
shiny wet and soft.
 Under-trituration: Alloy will be
dry, dull and crumbly; will crumble
if dropped from approx 30 cm.
 Normal Mix: Shiny appearance
separates in a single mass from the
capsule.
Under-trituration
Normal Mix
Objectives of Trituration are:
 To achieve a workable mass of amalgam within a
minimum time
 To remove the oxide layer
 To pulverize pellets into particles, that can be easily
attacked by the mercury.
 To reduce particle size
 To keep the amount of 1 or 2 matrix crystal as
minimal as possible, yet evenly distributed
Mixing variables
1) Working time & dimensional change
All types of amalgam, spherical or irregular –
decreases with overtrituration
Overtrituration – slightly higher contraction for all
types of alloys
2) Compressive & tensile strength
 Irregular shaped alloys – increase by overtrituration
 Spherical alloys -- greatest at normal trituration time
3) Creep
 Overtrituration increases creep
 Undertrituration lowers it
Condensation
 Refers to the incremental placement
of the amalgam into the prepared
cavity and compression of each
increment into the others
 Amalgam should be condensed into
the cavity within 3 min after
trituration.
Aims of condensation
 Adapt amalgam to the margins, walls and line angles
of the cavity.
 Minimize voids and layering between increments
within the amalgam.
 Develop maximum physical properties.
 Remove excess mercury to leave an optimal alloy:
mercury ratio.
Purpose of Condensation
 To get a continuous homogenous mass that is well
adapted to all margins, walls and line angles.
 Best carried out using hand instruments.
Hand condenser :
 Should allows a operator to
readily grasp it & exert a force
of condensation
 Size of condenser tip &
direction & magnitude of the
force placed, depends on the
type of amalgam alloy selected
 Irregular shaped alloys –
Condensers with relatively small tip, 1 to 2 mm
High condensation forces in vertical direction
As much mercury-rich mass as possible should be
removed
 Spherical amalgam alloys
Condensers with large tips are used
Condensed in lateral direction
High copper spherical amalgams – vertical & lateral
direction condensation with vibration
 Condensation pressure – load of 15 lb is
recommended to be applied to each increment
Mechanical Condensers:
 Useful for condensing irregular shaped alloys when
high condensation forces are required
 Need was eliminated with the advent of spherical
alloys
 Tend to lead to unreliable condensation as well as
generation of heat and mercury vapor, both of which
are undesirable.
Ultrasonic Condensers:
 Not recommended
 Causes the release of considerable quantities of
mercury vapor in the dental office
SPEED OF PLACEMENT
 Once amalgam is triturated, phase formation
commences and the setting reaction is underway.
 Amalgam must be placed in a plastic state
 No amalgam should 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.
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.
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.
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.
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
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).
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
 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.
RESISTANCE & RETENTION FORMS
Primary retention form
Attained by:
 Mechanical locking of
inserted amalgam into
surface irregularities to
allow good adaptation
 Preparation of vertical
walls that converge
occlusally
Primary resistance form
 For tooth :
Maintaining as much unprepared tooth structure as
possible
Having pulpal & gingival walls perpendicular to
occlusal forces
Having rounded internal prepartaion angles
Removing unsupported & weakened tooth structure
 Placing pins into the tooth as a part of final stage of
tooth preparation
Primary resistance form
 For amalgam :
 Adequate thickness – 1.5 -2 mm in areas of occlusal
contact, 0.75 mm in axial areas
Marginal amalgam of 90 degrees or greater
Box like preparation form
 Rounded axiopulpal line angles in class II
preparations
Secondary resistance & retention
form
 When insufficient
resistance/retention forms are
present in tooth, additional
preparation is indicated
 Such features include :
 Placement of grooves, locks,
coves, pins, slots or amalgam pins
 Larger the tooth preparation,
greater the need of secondary
resistance & retention forms
BIO-COMPATIBILITY –MERCURY
TOXICITY
 Amalgams have been used for 150 years
 About 200 million amalgams are inserted each year in
the United States and Europe
 Concern -- mercury in dental amalgam may pose
threats to the health of patients, to the health of
dental care providers and to the environment.
Mercury is available in 3 forms:
 Elemental mercury (liquid or vapor).
 Inorganic compounds.
 Organic compounds.
 ELEMENTAL MERCURY
Liquid mercury:
 Absorbed relatively poorly across skin or mucosa.
Most mercury becomes charged (ionized) before it
reaches the blood.
Ionized mercury is excreted well through kidneys and
urine.
There is no known risk to patients from liquid
mercury.
 ELEMENTAL MERCURY
Mercury vapor:
Less benign -- rapidly absorbed into the blood via the
lungs , remains uncharged and therefore highly lipid
soluble, for several minutes.
Can cross the blood-brain barrier where it becomes
charged and exists in extra cellular fluid of the brain
and returns into the blood much more slowly.
 High tissue levels- can lead to impaired brain
function, insanity and death may occur at 4000 g/kg.
 Low tissue levels- can lead to restlessness, tremors,
and loss of concentration.
Inorganic compounds of mercury
 S0urce – Drinking water, food
 Amalgam contains several different inorganic mercury
compounds,
 They are of low or very low toxicity and are apparently
harmless when swallowed.
 Poorly absorbed, do not accumulate in body tissues
and are well excreted.
Organic compounds of mercury
 Source -- Drinking water, food (sea food)
 Some organic compounds of mercury are highly toxic
at low concentrations
 But none are known to form in the oral environment
through dental amalgam use.
Source g Hg vapour g inorganic Hg g methyl Hg
Atmosphere 0.12 0.038 0.034
Drinking Water --- 0.05 ---
Food & Fish 0.94 --- 3.76
Food & Non-Fish --- 20.00 ---
ESTIMATED DAILY INTAKE OF MERCURY
CONCENTRATIONS OF MERCURY
 The Occupational Safety & Health Administration
(OSHA) has set a TLV of 0.05 mg/m3 as the maximum
amount of mercury vapor allowed in the work place.
 Average Daily dose of mercury from dental amalgam
for patients with more than 12 restored surfaces has
been estimated at up to 3 g.
CONCENTRATIONS OF MERCURY
Clarkson TW (1997) --
 Lowest dose of mercury that elicits a toxic reaction –
3to7 g/kg body weight
 Paresthesia -- 500 g/kg body weight
 Ataxia -- 1000 g/kg body weight
 Joint pain -- 2000 g/kg body weight
 Hearing loss & death -- 4000 g/kg body weight
CONCENTRATIONS OF MERCURY
Mercury release has been quantified for a number of
procedures:
 Trituration: 1-2g
 Placement of amalgam restoration: 6-8 g.
 Dry polishing: 44 g.
 Wet polishing: 2-4 g.
 Amalgam removal under water spray & high
velocity suction: 15-20 g
CONCENTRATIONS OF MERCURY
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
passivating surface oxide film-although this re-forms
rapidly.
Mercury in urine
 Body cannot retain metallic mercury, but passes it
through urine
 Skare I et al (1990) –
urine mercury level peak at 2.54 g/L 4 days after
placing amalgam restorations, return to zero after 7
days
On removal of amalgam, urine mercury levels reach a
maximum value of 4g/L, return to zero after 7 days
Mercury in blood
 Maximum allowable level of mercury in blood is 3
g/L
 Chang SB et al(1992) showed that freshly placed
amalgam restorations elevated blood mercury
levels to 1 to 2 g/L
 As with urine mercury levels, there is first an
increase of around 1.5 g/L, which decreases in
about 3 days
 Ott KH et al (1996) monitored blood mercury levels for 1
year, showed that patients with amalgams had lower than
average blood mercury level (0.6 g/L ) than patients
without amalgams (0.8 g/L )
 Mackert JR et al(1997) indicated higher blood
mercury levels in dentists, stated that -
 elevated blood mercury levels may relate to mercury
spills in the office
Both blood & serum mercury levels seem to correlate
best with occupational exposure, not with number of
amalgam & length of time with amalgam in place
BIO-COMPATIBILITY –MERCURY
TOXICITY
Sensitivity to amalgam restorations
 Skin lesions being more common than oral lesions.
 An urticarial rash may appear on the face and limbs and
this may be followed by dermatitis.
 Long- term response -- oral lichen planus or lichenoid
reactions with erosive areas on the tongue or buccal
mucosa adjacent to an amalgam restoration.
BIO-COMPATIBILITY –MERCURY
TOXICITY
AMALGAM TATTOO
AMALGAM TATTOO
Possible causes are:
 Scraps of amalgam may fall into open surgical or
extraction wounds.
 Excess amalgam may be left in the tissues following
sealing the apex of a root canal with a retrograde
amalgam.
 Pieces of amalgam may be forced into the mucosa.
Sources of Mercury Exposure in
Dental Office:
 Dental amalgam raw materials being stored for use.
 Mixed but unhardened dental amalgam during
triturations, insertion and intraoral setting.
 Dental amalgam scrap that has insufficient alloy to
completely consume the mercury present.
 Dental amalgam undergoing finishing and polishing
procedure.
 Dental amalgam restoration being removed.
DENTAL MERCURY HYGIENE
Recommendations from the ADA include the following:
 The work place should be well ventilated, with fresh air
exchange and outside exhaust
 Use only precapsulated alloy, discontinue use of Bulk
mercury & bulk alloy
 Avoid the need to remove excess mercury before or
during packing by selecting an appropriate alloy:
mercury ratio
 Use an amalgamator with a completely enclosed arm.
 Mercury and unset amalgam should not be touched by
the bare hands.
 Floor coverings should be non absorbent & easy to
clean
 Spilled mercury should be cleaned up using trap
bottles, tape or freshly mixed amalgam to pick up
droplets
 Do not use a house hold vaccum cleaner to clean
spilled mercury.
 Skin accidentally contaminated by mercury should be
washed thoroughly with soap and water.
 If a mercury hygiene problem is suspected, personnel
should undergo urine analysis to detect mercury levels
 Remove professional clothing before leaving the work
place
Scrap amalgam disposal
 In a tightly closed container
 Under radiographic fixer solution
 Dispose mercury contaminated items in sealed bags
 Donot dispose mercury contaminated items in
medical waste containers or bags or along with the
waste that will be incenerated
CLINICAL TECHIQUES TO ENHANCE
MARGINAL SEAL
1) Copal resin varnish:
 Apply two thick coats to the cavity walls and margins
before placing the amalgam and it will gradually
dissolve, beginning at the cavosurface, over 2-3
months.
 As the varnish dissolves out, the gap will be filled with
corrosion products from the amalgam and dissolution
of the varnish will cease.
CLINICAL TECHIQUES TO ENHANCE
MARGINAL SEAL
2) Glass-ionomer linings
 Placed under an amalgam will seal the dentinal
tubules and release small quantities of fluoride
 Will not affect enamel margins or enhance the seal at
the margin.
CLINICAL TECHIQUES TO ENHANCE
MARGINAL SEAL
3) Oxalate solutions :
 Such as potassium oxalate, can be applied to the
cavity surface to reduce the permeability of the tubules
and possibly seal the dentine.
 The crystals this deposited will not wash out but will
allow deposition of corrosion products.
RECENT ADVANCES
1) BONDED AMALGAMS
 During the 1990’s some clinicians began to routinely
bond amalgam restorations to enamel and dentine
 After preparation of the cavity, enamel and dentine
etched using a conventional etchant, a chemically
cured resin-bonding agent applied to the walls of the
cavity.
 Amalgam is immediately condensed into the cavity
before the resin bond has cured
Advantages of Bonded-Amalgam :
 Conservation of tooth structure.
 Fracture strength was as high as for composites
 Decreased marginal leakage in class 5 restorations
compared with unbonded amalgams
 Some operators claim elimination of post-insertion
sensitivity.
 Reduces incidence of marginal fracture and recurrent
caries.
 Can be done in single sitting.
 Allows for amalgam repairs.
Disadvantages of Bonded-Amalgam :
 Clinical difficulty of application of more viscous bonding
agents
 Lightly filled resin bonding agents tend to pool at the
gingival margin resulting in a higher potential for micro
leakage.
 Carving is difficult.
 Requires practitioner to adapt to new technique.
 Increases cost of amalgam restorations.
2) Gallium alloys
 Mercury free metallic restorative materials proposed as
substitute for mercury containing amalgam are gallium
containing materials and pure silver and/or silver based
alloys
 Puttkammer (1928), suggested the use of gallium in
dental restoration
 Attempts to develop satisfactory gallium restorative
materials were unsuccessful until Smith et al in 1956,
showed that improved Pd-Ga and Ag-Ga materials has
physical and mechanical properties that were similar to or
even better than those of silver amalgam.
ADVANTAGES OF GALLIUM BASED ALLOYS:
 Rapid solidification.
 Good marginal seal by expanding on solidification.
 Heat resistant.
 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
REACTION :
Ag3Sn + Ga  Ag3Ga + Sn.
REACTION :
 After mixing, the alloy tends to adhere to the walls of
capsule, thus difficult to handle.
 Moreover, by adding few drops of alcohol, the problem
of sticking can be minimized.
Biologic considerations of Gallium based alloys :
 Surface roughness, marginal discoloration and fracture
were reported. With improvement in composition,
these defects were reduced but not eliminated
 Could not be used in larger restorations as the
considerable setting amount of expansion leads to
fracture of cusps and post operative sensitivity.
 Cleaning of instruments tips is also difficult
 Less popular because it is costlier than amalgam.
3) Fluoride releasing amalgam
 Have been shown to have anticaries properties sufficient to
inhibit the development of caries in cavity walls.
 Concentration of fluoride is sufficient to enhance
remineralization
 Tviet and Lindh (1980) -- greatest concentration of
fluoride i.e. about 4000µg/mL in enamel surfaces exposed
to fluoride-containing amalgams were found in the outer
0.05µm of the tissue.
 In dentin, the greatest concentrations, i.e. about
9000µg/ml were found at a depth of 11.5µm.
 However, this release of fluoride decreases to minor
amounts after 1 week.
 Forsten L (1976) -- fluoride released from amalgams
loaded with soluble fluoride salts was detectable
within the first month and thereafter fluoride was not
released in measurable amounts.
 Garcia Godoy et al( 1990) – fluoride release can
continue as long as 2 years (but at a much lower rate
than that for GIC).
Marginal fracture of amalgam
 Referred to as “Marginal
breakdown”, “ditching”, and
“crevice formation”.
 Regardless of the type of
amalgam, marginal fracture
increases with time
 The rate of increase is greater for
low-copper amalgams.
CLINICAL TECHNIQUES TO PREVENT
MARGINAL FRACTURE
 Excess amalgam, left lying over the occlusal or
proximal surface should be carved correctly
 The angle of the carvo-surface margin should be
greater than 70º and the cavity should be designed to
allow for this.
 On completion of packing, burnish the margins both
before and after carving to improve marginal
adaptation.
Repair Of Amalgam Restorations
 When an amalgam restoration fails, as from marginal
fracture, it is repaired
 A new mix of amalgam is condensed against the
remaining part of the existing restoration
 The strength of the bond between the new and the old
amalgam is important
Factors contributing to strength of
repair
 Presence of porosity and  phase at the junction.
 Inadequate condensation.
 Contamination of the surface of the existing amalgam.
 Corrosion & contamination from saliva.
CLINICAL CONSIDERATIONS
Marginal Adaptation And Seal :
 Lack of marginal adaptation in first few weeks
 May be associated with marginal deterioration,
accumulation of debris, recurrent caries, post-
restoration sensitivity or pulpal reactions.
CLINICAL CONSIDERATIONS
Self-Sealing :
 After 48 hours, “self sealing” occurs
 Low-copper amalgam -- seal within 2-3 months
 High-copper amalgams -- corrode less and therefore
take 10-12 months to provide a comparable seal.
Amalgam wars
 In 1845, American Society of Dental Surgeons condemned
the use of all filling material other than gold as toxic,
thereby igniting "first amalgam war'. The society went
further and requested members to sign a pledge refusing to
use amalgam.
 In mid 1920's a German dentist, Professor A. Stock started
the so called "second amalgam war". He claimed to have
evidence showing that mercury could be absorbed from
dental amalgam, which leads to serious health problems.
He also expressed concerns over health of dentists, stating
that nearly all dentists had excess mercury in their urine.
Amalgam wars
 "Third Amalgam War' began in 1980 primarily
through the seminars and writings of Dr.Huggins, a
practicing dentist in Colorado.
 He was convinced that mercury released from dental
amalgam was responsible for human diseases affecting
the cardiovascular system and nervous system
 Also stated that patients claimed recoveries from
multiple sclerosis, Alzheimer’s disease and other
diseases as a result of removing their dental amalgam
fillings.
CONCLUSION
There are certain advantages inherent with amalgam
such as technique insensitive, excellent wear
resistance, less time consuming, less expensive which
are not present in the newer materials, these factors
will continue 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.
 Craig, “Science of Dental Materials”.
 Jagannathan, K, “Cruise for Gamma 2 Free Mercury”, “Materials in
Restorative Dentistry”, MADC & H, 1998 66-69.
 John F. McCabe, Angus W.G. Walls, “Dental Amalgam”, Applied Dental
Materials, Blackwell Science, 8th Edition, 1998:157-168
 Satish Chandra, Shaleen Chandra, “Dental Amalgam”, A Text Book of
Dental materials with Multiple Choice Questions”, Jaypee Brothers; 1st
Edition 2000.
 Vimal. K. Sikri, “Silver Amalgam”, Text book of Operative Dentistry”
CBS publishers, 1st Edition 2002, 204-242.
Thank you…

More Related Content

What's hot

Heat cure acrylic
Heat cure acrylicHeat cure acrylic
Heat cure acrylicAamir Godil
 
Steps Of Cavity Preparation
Steps Of Cavity PreparationSteps Of Cavity Preparation
Steps Of Cavity PreparationAbhinav Mudaliar
 
Hand instruments in operative dentistry
Hand instruments in operative dentistryHand instruments in operative dentistry
Hand instruments in operative dentistryAbhijeet Khade
 
DENTIN BONDING AGENTS
 DENTIN BONDING AGENTS DENTIN BONDING AGENTS
DENTIN BONDING AGENTSshibil_v90
 
steps of cavity preparation for class 1
steps of cavity preparation for class 1 steps of cavity preparation for class 1
steps of cavity preparation for class 1 Parikshit Harnoor
 
Fundamentals in tooth preparation .
Fundamentals in tooth preparation .Fundamentals in tooth preparation .
Fundamentals in tooth preparation .Priyesh Kharat
 
Dental bases and liners
Dental bases and linersDental bases and liners
Dental bases and linersIAU Dent
 
Modifications of Class 2 Cavity preparations
Modifications of Class 2 Cavity preparationsModifications of Class 2 Cavity preparations
Modifications of Class 2 Cavity preparationsDr. Arpit Viradiya
 
Principles of teeth arrangement and compensatory curves
Principles of teeth arrangement and compensatory curves Principles of teeth arrangement and compensatory curves
Principles of teeth arrangement and compensatory curves Huma Javeria
 

What's hot (20)

Dental ceramics
Dental ceramicsDental ceramics
Dental ceramics
 
Heat cure acrylic
Heat cure acrylicHeat cure acrylic
Heat cure acrylic
 
Amalgam
AmalgamAmalgam
Amalgam
 
Steps Of Cavity Preparation
Steps Of Cavity PreparationSteps Of Cavity Preparation
Steps Of Cavity Preparation
 
Hand instruments in operative dentistry
Hand instruments in operative dentistryHand instruments in operative dentistry
Hand instruments in operative dentistry
 
DENTIN BONDING AGENTS
 DENTIN BONDING AGENTS DENTIN BONDING AGENTS
DENTIN BONDING AGENTS
 
Impression materials
Impression materialsImpression materials
Impression materials
 
steps of cavity preparation for class 1
steps of cavity preparation for class 1 steps of cavity preparation for class 1
steps of cavity preparation for class 1
 
Fundamentals in tooth preparation .
Fundamentals in tooth preparation .Fundamentals in tooth preparation .
Fundamentals in tooth preparation .
 
Dental bases and liners
Dental bases and linersDental bases and liners
Dental bases and liners
 
dentin bonding agents
dentin bonding agentsdentin bonding agents
dentin bonding agents
 
GIC
GICGIC
GIC
 
Dental amalgam
Dental amalgamDental amalgam
Dental amalgam
 
Wedging technique
Wedging techniqueWedging technique
Wedging technique
 
Modifications of Class 2 Cavity preparations
Modifications of Class 2 Cavity preparationsModifications of Class 2 Cavity preparations
Modifications of Class 2 Cavity preparations
 
Cavity preparation
Cavity preparationCavity preparation
Cavity preparation
 
Principles of teeth arrangement and compensatory curves
Principles of teeth arrangement and compensatory curves Principles of teeth arrangement and compensatory curves
Principles of teeth arrangement and compensatory curves
 
Acid Etching of Enamel and Bond Strength
Acid Etching of Enamel and Bond StrengthAcid Etching of Enamel and Bond Strength
Acid Etching of Enamel and Bond Strength
 
Direct filling gold
Direct filling goldDirect filling gold
Direct filling gold
 
Class i cavity preparation
Class i cavity preparationClass i cavity preparation
Class i cavity preparation
 

Viewers also liked

Manipulation of amalgam
Manipulation of amalgamManipulation of amalgam
Manipulation of amalgamRohan Vadsola
 
amalgam manipulation dental material
amalgam manipulation dental material amalgam manipulation dental material
amalgam manipulation dental material Dr-Faisal Al-Qahtani
 
bonding to tooth structure dental material
bonding to tooth structure dental materialbonding to tooth structure dental material
bonding to tooth structure dental materialDr-Faisal Al-Qahtani
 
Glass Ionomer cement & it's advancement.
Glass Ionomer cement & it's advancement.Glass Ionomer cement & it's advancement.
Glass Ionomer cement & it's advancement.Sk Aziz Ikbal
 
Behavioral Management Technique For Patient With Special Needs
Behavioral Management Technique For Patient With Special Needs Behavioral Management Technique For Patient With Special Needs
Behavioral Management Technique For Patient With Special Needs DrGhadooRa
 
Tooth examination
Tooth examinationTooth examination
Tooth examinationDrGhadooRa
 
Composi-Tight 3D™ Sectional Matrix
Composi-Tight 3D™ Sectional MatrixComposi-Tight 3D™ Sectional Matrix
Composi-Tight 3D™ Sectional MatrixDrGhadooRa
 
The anterior portion of intraoral radiographs
The anterior portion of intraoral radiographsThe anterior portion of intraoral radiographs
The anterior portion of intraoral radiographsDrGhadooRa
 
Clinical Examination Of Fixed Prosthodontics
Clinical Examination Of Fixed ProsthodonticsClinical Examination Of Fixed Prosthodontics
Clinical Examination Of Fixed ProsthodonticsDrGhadooRa
 
Mucus VS Serous
Mucus VS	SerousMucus VS	Serous
Mucus VS SerousDrGhadooRa
 
Pulp Protection
Pulp ProtectionPulp Protection
Pulp Protectionshabeel pn
 
Zones of enamel and dentin caries
Zones of enamel and dentin cariesZones of enamel and dentin caries
Zones of enamel and dentin cariesZY The Ripper
 
Resin bonded bridge: A forgotten first frontier for an aesthetically critical...
Resin bonded bridge: A forgotten first frontier for an aesthetically critical...Resin bonded bridge: A forgotten first frontier for an aesthetically critical...
Resin bonded bridge: A forgotten first frontier for an aesthetically critical...iosrjce
 
Amalgam &composite
Amalgam &compositeAmalgam &composite
Amalgam &compositeDrGhadooRa
 

Viewers also liked (20)

Manipulation of amalgam
Manipulation of amalgamManipulation of amalgam
Manipulation of amalgam
 
amalgam manipulation dental material
amalgam manipulation dental material amalgam manipulation dental material
amalgam manipulation dental material
 
bonding to tooth structure dental material
bonding to tooth structure dental materialbonding to tooth structure dental material
bonding to tooth structure dental material
 
Glass Ionomer cement & it's advancement.
Glass Ionomer cement & it's advancement.Glass Ionomer cement & it's advancement.
Glass Ionomer cement & it's advancement.
 
bonding to enamel & dentin
bonding to enamel & dentinbonding to enamel & dentin
bonding to enamel & dentin
 
Amalgam
AmalgamAmalgam
Amalgam
 
Behavioral Management Technique For Patient With Special Needs
Behavioral Management Technique For Patient With Special Needs Behavioral Management Technique For Patient With Special Needs
Behavioral Management Technique For Patient With Special Needs
 
Tooth examination
Tooth examinationTooth examination
Tooth examination
 
Composi-Tight 3D™ Sectional Matrix
Composi-Tight 3D™ Sectional MatrixComposi-Tight 3D™ Sectional Matrix
Composi-Tight 3D™ Sectional Matrix
 
The anterior portion of intraoral radiographs
The anterior portion of intraoral radiographsThe anterior portion of intraoral radiographs
The anterior portion of intraoral radiographs
 
Clinical Examination Of Fixed Prosthodontics
Clinical Examination Of Fixed ProsthodonticsClinical Examination Of Fixed Prosthodontics
Clinical Examination Of Fixed Prosthodontics
 
Mucus VS Serous
Mucus VS	SerousMucus VS	Serous
Mucus VS Serous
 
Pulp Protection
Pulp ProtectionPulp Protection
Pulp Protection
 
Zones of enamel and dentin caries
Zones of enamel and dentin cariesZones of enamel and dentin caries
Zones of enamel and dentin caries
 
Design Factors in Orthodontic Appliance
Design Factors in Orthodontic Appliance Design Factors in Orthodontic Appliance
Design Factors in Orthodontic Appliance
 
Resin bonded bridge: A forgotten first frontier for an aesthetically critical...
Resin bonded bridge: A forgotten first frontier for an aesthetically critical...Resin bonded bridge: A forgotten first frontier for an aesthetically critical...
Resin bonded bridge: A forgotten first frontier for an aesthetically critical...
 
Amalgam restoration
Amalgam restorationAmalgam restoration
Amalgam restoration
 
EEG Epilepsy
EEG EpilepsyEEG Epilepsy
EEG Epilepsy
 
Amalgam &composite
Amalgam &compositeAmalgam &composite
Amalgam &composite
 
About Pulp
About PulpAbout Pulp
About Pulp
 

Similar to Dental Amalgam

Dental Amalgam & Mercury Toxicity
Dental Amalgam & Mercury ToxicityDental Amalgam & Mercury Toxicity
Dental Amalgam & Mercury ToxicityHarshita Lath
 
Failure of amalgam
Failure of amalgamFailure of amalgam
Failure of amalgamAnoop Nair
 
Amalgam and Composite
 Amalgam and Composite  Amalgam and Composite
Amalgam and Composite CmenonMenon
 
fdocuments.in_dental-amalgam-55844f6d7eae0.ppt
fdocuments.in_dental-amalgam-55844f6d7eae0.pptfdocuments.in_dental-amalgam-55844f6d7eae0.ppt
fdocuments.in_dental-amalgam-55844f6d7eae0.pptDrHIMANSHUTIWARI1
 
DENTAL AMALGAM/prosthodontic courses
DENTAL AMALGAM/prosthodontic coursesDENTAL AMALGAM/prosthodontic courses
DENTAL AMALGAM/prosthodontic coursesIndian dental academy
 
Posterior restorations.....
Posterior restorations.....Posterior restorations.....
Posterior restorations.....Neha Bemalgi
 
dental amalgam May 2020....class 1 class 2
dental amalgam May 2020....class 1 class 2dental amalgam May 2020....class 1 class 2
dental amalgam May 2020....class 1 class 2AdwayaPingale
 
Dental Casting alloys
 Dental Casting alloys Dental Casting alloys
Dental Casting alloysNivedha Tina
 
Dental casting alloys
Dental casting alloysDental casting alloys
Dental casting alloysLama K Banna
 
Dental casting alloys in prosthodontics crown bridge and implant
Dental casting alloys in prosthodontics crown bridge and implantDental casting alloys in prosthodontics crown bridge and implant
Dental casting alloys in prosthodontics crown bridge and implantChaithanyaChaithu42
 
Cast gold Inlay restorations
Cast gold Inlay restorationsCast gold Inlay restorations
Cast gold Inlay restorationsAbhijeet Khade
 

Similar to Dental Amalgam (20)

Dental Amalgam & Mercury Toxicity
Dental Amalgam & Mercury ToxicityDental Amalgam & Mercury Toxicity
Dental Amalgam & Mercury Toxicity
 
Failure of amalgam
Failure of amalgamFailure of amalgam
Failure of amalgam
 
Amalgam and Composite
 Amalgam and Composite  Amalgam and Composite
Amalgam and Composite
 
Dental amalagam
Dental amalagamDental amalagam
Dental amalagam
 
Dental amalgams
Dental amalgamsDental amalgams
Dental amalgams
 
Amalgam
AmalgamAmalgam
Amalgam
 
Amalgam
AmalgamAmalgam
Amalgam
 
fdocuments.in_dental-amalgam-55844f6d7eae0.ppt
fdocuments.in_dental-amalgam-55844f6d7eae0.pptfdocuments.in_dental-amalgam-55844f6d7eae0.ppt
fdocuments.in_dental-amalgam-55844f6d7eae0.ppt
 
DENTAL AMALGAM/prosthodontic courses
DENTAL AMALGAM/prosthodontic coursesDENTAL AMALGAM/prosthodontic courses
DENTAL AMALGAM/prosthodontic courses
 
Posterior restorations.....
Posterior restorations.....Posterior restorations.....
Posterior restorations.....
 
dental amalgam May 2020....class 1 class 2
dental amalgam May 2020....class 1 class 2dental amalgam May 2020....class 1 class 2
dental amalgam May 2020....class 1 class 2
 
Amalgam Fillings
Amalgam FillingsAmalgam Fillings
Amalgam Fillings
 
Dental Casting alloys
 Dental Casting alloys Dental Casting alloys
Dental Casting alloys
 
Historical perspective
Historical perspectiveHistorical perspective
Historical perspective
 
Amalgam
AmalgamAmalgam
Amalgam
 
Dental casting alloys
Dental casting alloysDental casting alloys
Dental casting alloys
 
Dental casting alloys in prosthodontics crown bridge and implant
Dental casting alloys in prosthodontics crown bridge and implantDental casting alloys in prosthodontics crown bridge and implant
Dental casting alloys in prosthodontics crown bridge and implant
 
Cast gold Inlay restorations
Cast gold Inlay restorationsCast gold Inlay restorations
Cast gold Inlay restorations
 
Amalgam
AmalgamAmalgam
Amalgam
 
Non ferrous alloy
Non ferrous alloyNon ferrous alloy
Non ferrous alloy
 

More from Piyush Verma

Isolation in dentistry
Isolation in dentistryIsolation in dentistry
Isolation in dentistryPiyush Verma
 
Eruption & shedding
Eruption & sheddingEruption & shedding
Eruption & sheddingPiyush Verma
 
Growth & development of maxilla and mandible
Growth & development of maxilla and mandibleGrowth & development of maxilla and mandible
Growth & development of maxilla and mandiblePiyush Verma
 
Development of occlusion.
Development of  occlusion.Development of  occlusion.
Development of occlusion.Piyush Verma
 
Development of tooth
Development of toothDevelopment of tooth
Development of toothPiyush Verma
 

More from Piyush Verma (6)

Isolation in dentistry
Isolation in dentistryIsolation in dentistry
Isolation in dentistry
 
Eruption & shedding
Eruption & sheddingEruption & shedding
Eruption & shedding
 
Growth & development of maxilla and mandible
Growth & development of maxilla and mandibleGrowth & development of maxilla and mandible
Growth & development of maxilla and mandible
 
Development of occlusion.
Development of  occlusion.Development of  occlusion.
Development of occlusion.
 
Cephalometrics
CephalometricsCephalometrics
Cephalometrics
 
Development of tooth
Development of toothDevelopment of tooth
Development of tooth
 

Recently uploaded

Physiology of Smooth Muscles -Mechanics of contraction and relaxation
Physiology of Smooth Muscles -Mechanics of contraction and relaxationPhysiology of Smooth Muscles -Mechanics of contraction and relaxation
Physiology of Smooth Muscles -Mechanics of contraction and relaxationMedicoseAcademics
 
blood bank management system project report
blood bank management system project reportblood bank management system project report
blood bank management system project reportNARMADAPETROLEUMGAS
 
Trustworthiness of AI based predictions Aachen 2024
Trustworthiness of AI based predictions Aachen 2024Trustworthiness of AI based predictions Aachen 2024
Trustworthiness of AI based predictions Aachen 2024EwoutSteyerberg1
 
ANATOMICAL FAETURES OF BONES FOR NURSING STUDENTS .pptx
ANATOMICAL FAETURES OF BONES  FOR NURSING STUDENTS .pptxANATOMICAL FAETURES OF BONES  FOR NURSING STUDENTS .pptx
ANATOMICAL FAETURES OF BONES FOR NURSING STUDENTS .pptxWINCY THIRUMURUGAN
 
Male Infertility, Antioxidants and Beyond
Male Infertility, Antioxidants and BeyondMale Infertility, Antioxidants and Beyond
Male Infertility, Antioxidants and BeyondSujoy Dasgupta
 
SGK RỐI LOẠN TOAN KIỀM ĐHYHN RẤT HAY VÀ ĐẶC SẮC.pdf
SGK RỐI LOẠN TOAN KIỀM ĐHYHN RẤT HAY VÀ ĐẶC SẮC.pdfSGK RỐI LOẠN TOAN KIỀM ĐHYHN RẤT HAY VÀ ĐẶC SẮC.pdf
SGK RỐI LOẠN TOAN KIỀM ĐHYHN RẤT HAY VÀ ĐẶC SẮC.pdfHongBiThi1
 
"Radical excision of DIE in subferile women with deep infiltrating endometrio...
"Radical excision of DIE in subferile women with deep infiltrating endometrio..."Radical excision of DIE in subferile women with deep infiltrating endometrio...
"Radical excision of DIE in subferile women with deep infiltrating endometrio...Sujoy Dasgupta
 
Female Reproductive Physiology Before Pregnancy
Female Reproductive Physiology Before PregnancyFemale Reproductive Physiology Before Pregnancy
Female Reproductive Physiology Before PregnancyMedicoseAcademics
 
ORAL HYPOGLYCAEMIC AGENTS - PART 2.pptx
ORAL HYPOGLYCAEMIC AGENTS  - PART 2.pptxORAL HYPOGLYCAEMIC AGENTS  - PART 2.pptx
ORAL HYPOGLYCAEMIC AGENTS - PART 2.pptxNIKITA BHUTE
 
How to cure cirrhosis and chronic hepatitis naturally
How to cure cirrhosis and chronic hepatitis naturallyHow to cure cirrhosis and chronic hepatitis naturally
How to cure cirrhosis and chronic hepatitis naturallyZurück zum Ursprung
 
pA2 value, Schild plot and pD2 values- applications in pharmacology
pA2 value, Schild plot and pD2 values- applications in pharmacologypA2 value, Schild plot and pD2 values- applications in pharmacology
pA2 value, Schild plot and pD2 values- applications in pharmacologyDeepakDaniel9
 
SGK NGẠT NƯỚC ĐHYHN RẤT LÀ HAY NHA .pdf
SGK NGẠT NƯỚC ĐHYHN RẤT LÀ HAY NHA    .pdfSGK NGẠT NƯỚC ĐHYHN RẤT LÀ HAY NHA    .pdf
SGK NGẠT NƯỚC ĐHYHN RẤT LÀ HAY NHA .pdfHongBiThi1
 
Role of Soap based and synthetic or syndets bar
Role of  Soap based and synthetic or syndets barRole of  Soap based and synthetic or syndets bar
Role of Soap based and synthetic or syndets barmohitRahangdale
 
Adenomyosis or Fibroid- making right diagnosis
Adenomyosis or Fibroid- making right diagnosisAdenomyosis or Fibroid- making right diagnosis
Adenomyosis or Fibroid- making right diagnosisSujoy Dasgupta
 
CPR.nursingoutlook.pdf , Bsc nursing student
CPR.nursingoutlook.pdf , Bsc nursing studentCPR.nursingoutlook.pdf , Bsc nursing student
CPR.nursingoutlook.pdf , Bsc nursing studentsaileshpanda05
 
ayurvedic formulations herbal drug technologyppt
ayurvedic formulations herbal drug technologypptayurvedic formulations herbal drug technologyppt
ayurvedic formulations herbal drug technologypptPradnya Wadekar
 
EXERCISE PERFORMANCE.pptx, Lung function
EXERCISE PERFORMANCE.pptx, Lung functionEXERCISE PERFORMANCE.pptx, Lung function
EXERCISE PERFORMANCE.pptx, Lung functionkrishnareddy157915
 

Recently uploaded (20)

Physiology of Smooth Muscles -Mechanics of contraction and relaxation
Physiology of Smooth Muscles -Mechanics of contraction and relaxationPhysiology of Smooth Muscles -Mechanics of contraction and relaxation
Physiology of Smooth Muscles -Mechanics of contraction and relaxation
 
blood bank management system project report
blood bank management system project reportblood bank management system project report
blood bank management system project report
 
Trustworthiness of AI based predictions Aachen 2024
Trustworthiness of AI based predictions Aachen 2024Trustworthiness of AI based predictions Aachen 2024
Trustworthiness of AI based predictions Aachen 2024
 
ANATOMICAL FAETURES OF BONES FOR NURSING STUDENTS .pptx
ANATOMICAL FAETURES OF BONES  FOR NURSING STUDENTS .pptxANATOMICAL FAETURES OF BONES  FOR NURSING STUDENTS .pptx
ANATOMICAL FAETURES OF BONES FOR NURSING STUDENTS .pptx
 
Male Infertility, Antioxidants and Beyond
Male Infertility, Antioxidants and BeyondMale Infertility, Antioxidants and Beyond
Male Infertility, Antioxidants and Beyond
 
SGK RỐI LOẠN TOAN KIỀM ĐHYHN RẤT HAY VÀ ĐẶC SẮC.pdf
SGK RỐI LOẠN TOAN KIỀM ĐHYHN RẤT HAY VÀ ĐẶC SẮC.pdfSGK RỐI LOẠN TOAN KIỀM ĐHYHN RẤT HAY VÀ ĐẶC SẮC.pdf
SGK RỐI LOẠN TOAN KIỀM ĐHYHN RẤT HAY VÀ ĐẶC SẮC.pdf
 
Rheumatoid arthritis Part 1, case based approach with application of the late...
Rheumatoid arthritis Part 1, case based approach with application of the late...Rheumatoid arthritis Part 1, case based approach with application of the late...
Rheumatoid arthritis Part 1, case based approach with application of the late...
 
"Radical excision of DIE in subferile women with deep infiltrating endometrio...
"Radical excision of DIE in subferile women with deep infiltrating endometrio..."Radical excision of DIE in subferile women with deep infiltrating endometrio...
"Radical excision of DIE in subferile women with deep infiltrating endometrio...
 
Female Reproductive Physiology Before Pregnancy
Female Reproductive Physiology Before PregnancyFemale Reproductive Physiology Before Pregnancy
Female Reproductive Physiology Before Pregnancy
 
ORAL HYPOGLYCAEMIC AGENTS - PART 2.pptx
ORAL HYPOGLYCAEMIC AGENTS  - PART 2.pptxORAL HYPOGLYCAEMIC AGENTS  - PART 2.pptx
ORAL HYPOGLYCAEMIC AGENTS - PART 2.pptx
 
How to cure cirrhosis and chronic hepatitis naturally
How to cure cirrhosis and chronic hepatitis naturallyHow to cure cirrhosis and chronic hepatitis naturally
How to cure cirrhosis and chronic hepatitis naturally
 
pA2 value, Schild plot and pD2 values- applications in pharmacology
pA2 value, Schild plot and pD2 values- applications in pharmacologypA2 value, Schild plot and pD2 values- applications in pharmacology
pA2 value, Schild plot and pD2 values- applications in pharmacology
 
SGK NGẠT NƯỚC ĐHYHN RẤT LÀ HAY NHA .pdf
SGK NGẠT NƯỚC ĐHYHN RẤT LÀ HAY NHA    .pdfSGK NGẠT NƯỚC ĐHYHN RẤT LÀ HAY NHA    .pdf
SGK NGẠT NƯỚC ĐHYHN RẤT LÀ HAY NHA .pdf
 
Biologic therapy ice breaking in rheumatology, Case based approach with appli...
Biologic therapy ice breaking in rheumatology, Case based approach with appli...Biologic therapy ice breaking in rheumatology, Case based approach with appli...
Biologic therapy ice breaking in rheumatology, Case based approach with appli...
 
Role of Soap based and synthetic or syndets bar
Role of  Soap based and synthetic or syndets barRole of  Soap based and synthetic or syndets bar
Role of Soap based and synthetic or syndets bar
 
Adenomyosis or Fibroid- making right diagnosis
Adenomyosis or Fibroid- making right diagnosisAdenomyosis or Fibroid- making right diagnosis
Adenomyosis or Fibroid- making right diagnosis
 
CPR.nursingoutlook.pdf , Bsc nursing student
CPR.nursingoutlook.pdf , Bsc nursing studentCPR.nursingoutlook.pdf , Bsc nursing student
CPR.nursingoutlook.pdf , Bsc nursing student
 
ayurvedic formulations herbal drug technologyppt
ayurvedic formulations herbal drug technologypptayurvedic formulations herbal drug technologyppt
ayurvedic formulations herbal drug technologyppt
 
How to master Steroid (glucocorticoids) prescription, different scenarios, ca...
How to master Steroid (glucocorticoids) prescription, different scenarios, ca...How to master Steroid (glucocorticoids) prescription, different scenarios, ca...
How to master Steroid (glucocorticoids) prescription, different scenarios, ca...
 
EXERCISE PERFORMANCE.pptx, Lung function
EXERCISE PERFORMANCE.pptx, Lung functionEXERCISE PERFORMANCE.pptx, Lung function
EXERCISE PERFORMANCE.pptx, Lung function
 

Dental Amalgam

  • 1. Presentation by: Dr. Piyush Verma Dept of Pedodontics & Preventive Dentistry
  • 2. Index  Introduction  History  Classification  Indications & contraindications  Advantages/disadvantages  Composition of amalgam & Amalgamation reactions  Manufacturing process  Properties of amalgam  Manipulation of amalgam
  • 3. Index  Mercury toxicity & various health hazards  Recent advances  Repair of amalgam restorations  Clinical considerations  Amalgam wars  Conclusion
  • 4. Introduction  Dental amalgam is an alloy made by mixing mercury with a silver tin alloy. Dental amalgam alloy is a silver tin alloy to which varying amount of copper and small amount of zinc has been added.  According to Skinner’s, amalgam is a special type of alloy in which one of its constituent is mercury. In dentistry, it is common to use the term amalgam to mean dental amalgam.
  • 5. History  Amalgam -- First used by Chinese. There is a mention of silver mercury paste by Sukung (659AD) in the Chinese medic  1578-lshitichen used 100 parts if Hg, 45 parts of Ag and 100 parts of Sn  Liu Wen-Thai (1508) and Li Shih-Chen (1578) discussed its formulation; 100 parts of mercury to 45 parts of silver and 900 parts of tin, trituration of these ingredients produced a paste said to be as solid as silver. .
  • 6.  Introduced in 1800’s in France alloy of bismuth, lead, tin and mercury plasticized at 100ºC poured directly into cavity  1819, Bell advocated the use of a room temperature mixed amalgam as a restorative material, in England  1826, M.Traveau is credited with advocating the first form of amalgam paste , in France.
  • 7.  1833  Crawcour brothers introduced amalgam to US  powdered silver coins mixed with mercury  expanded on setting  1895  To overcome expansion problems  G.V. Black developed a formula for modern amalgam alloy  67% silver, 27% tin, 5% copper, 1% zinc
  • 8.  Black’s formula was well accepted and not much changed for nearly sixty years.(1890-1963)  1946 - Skinner, added copper to the amalgam alloy composition in a small amount. This served to increase strength and decrease flow. 
  • 9.  Traditional or conventional amalgam alloys predominated from 1900 to 1970.  1960’s - conventional low-copper lathe-cut alloy was introduced  1962 - A spherical particle dental alloy was introduced, by Demaree and Taylor
  • 10.  The work of Innes and Youdeis (1963) has led to the development of high copper alloys.  Had longer working time, less dimensional change, easy to finish, set faster, low residual mercury, low creep & higher early strength  Added spherical silver copper eutectic alloy(71.9wt% Ag and 28.1wt%Cu)particles to lathe cut low copper amalgam alloy particles.  These alloys are called admixed alloys
  • 11.  1971 – Johnson designed a spherical particle alloy having the composition 64% Ag, 26% Sn and 10% cu by weight, and exhibiting no Sn8Hg after amalgamation.  1973 - first single composition spherical alloy named Tytin (Kerr) a ternary system (silver/tin/copper) was discovered by Kamal Asgar of the University of Michigan  1980’s alloys similar to Dispersalloy and Tytin was introduced
  • 12. Classification (Marzouk) I. According to number of alloy metals: 1. Binary alloys (Silver-Tin) 2. Ternary alloys (Silver-Tin-Copper) 3. Quaternary alloys (Silver-Tin-Copper-Indium).
  • 13. II.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
  • 14.  III. According to the shape of the powdered particles.  1. Spherical shape (smooth surfaced spheres).  2. Lathe cut (Irregular ranging from spindles to shavings).  3. Combination of spherical and lathe cut (admixed).  IV. According to Powder particle size.  1. Micro cut  2. Fine cut  3. Coarse cut
  • 15.  V. According to copper content of powder  1. Low copper content alloy - Less than 4%  2. High copper content alloy - more than 10%  VI. According to addition of Nobel metals  Platinum  Gold  Pallidum
  • 16.  VII. 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).
  • 17.  According to Presence of zinc.  Zinc containing (more than 0.01%).  Non zinc containing (less than 0.01%).
  • 18. 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
  • 19. INDICATIONS OF AMALGAM  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.
  • 20. CONTRA INDICATIONS 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
  • 21. 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.
  • 22. Advantages  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.
  • 23. 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).
  • 24. Composition of amalgam Conventional Amalgam Alloys: (G.V. Black’s: Silver- tin alloy or Low copper alloy).  Low copper alloys are available as comminuted particles (Lathe -cut and Pulverized) and spherical particles. Low copper composition:  Silver : 63-70%  Tin : 26-28%  Copper : 2- 5%  Zinc : 0-2%
  • 25. 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.
  • 26. 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.
  • 27. 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.
  • 28. HIGH COPPER AMALGAM ALLOY (COPPER ENRICHED ALLOYS)  To overcome the inferior properties of low copper amalgam alloy -- shorter working time, more dimensional change, difficult to finish, set late, high residual mercury, high creep & lower early strength, low fracture resistant  Youdelis and Innes in 1963 introduced high copper content amalgam alloys. They increased the copper content from earlier used 5% to 12%.  Copper enriched alloys are of two types: 1) Admixed alloy powder. 2) Single composition alloy powder.
  • 29. I. Admixed alloy powder:  Also called as blended alloys.  Contain 2 parts by weight of conventional composition lathe cut particles plus one part by weight of spheres of a silver copper eutectic alloy.  Made by mixing particles of silver and tin with particles of silver and copper.  The silver tin particle is usually formed by the lathe cut method, whereas the silver copper particle is usually spherical in shape.
  • 30. I. Admixed alloy powder: Composition:  Silver-69 %  Copper-13 %  Tin-17 %  Zinc-1 %
  • 31. I. Admixed alloy powder:  Amalgam made from these powders are stronger than amalgam made from lathe cut low copper alloys because of strength of Ag-Cu eutectic alloy particles.  Ag-Cu particles probably act as strong fillers strengthening the amalgam matrix.  Total copper content ranges from 9-20%.
  • 32. II. Single composition alloy (Unicomposition):  It is so called as it contains particles of same composition.  Usually spherical single composition alloys are used.  As lathe cut, high copper alloys contain more than 23% copper.
  • 33. II. Single composition alloy (Unicomposition): 1. Ternary alloy in spherical form, silver 60%, tin 25%, copper 15%. 2.Quaternary alloy in spheroidal form containing Silver: 59%, copper 13%, tin: 24%, indium 4%.
  • 34. AMALGAMATION REACTION/ SETTING REACTION Low copper conventional amalgam alloy  Dissolution and precipitation  Hg dissolves Ag and Sn from alloy  Intermetallic compounds formed Ag3Sn + Hg  Ag3Sn + Ag2Hg3 + Sn8Hg Ag-Sn Alloy Ag-Sn Alloy Ag-Sn Alloy Mercury (Hg) Sn Sn Sn Ag Hg Hg Ag Ag  1 2
  • 35. Low copper conventional amalgam alloy  Gamma () = Ag3Sn  unreacted alloy  strongest phase and corrodes the least  forms 30% of volume of set amalgam Ag-Sn Alloy Ag-Sn Alloy Ag-Sn Alloy Mercury Ag Sn Sn Sn Ag Hg Hg Ag Hg
  • 36. Low copper conventional amalgam alloy  Gamma 1 (1) = Ag2Hg3  matrix for unreacted alloy and 2nd strongest phase  10 micron grains binding gamma ()  60% of volume Ag-Sn Alloy Ag-Sn Alloy Ag-Sn Alloy 1
  • 37. Low copper conventional amalgam alloy  Gamma 2 (2) = Sn8Hg  weakest and softest phase  corrodes fast, voids form  corrosion yields Hg which reacts with more gamma ()  10% of volume  volume decreases with time due to corrosion 2 Ag-Sn Alloy Ag-Sn Alloy Ag-Sn Alloy
  • 38. Admixed High-Copper Alloys Initial reaction Ag3Sn + Ag-Cu + Hg Ag3Sn + Ag2Hg3 + Sn8Hg + Ag-Cu Ag-Sn Alloy Ag-Sn Alloy Mercury Ag AgAg Sn Sn Ag-Cu Alloy Ag HgHg   1 2
  • 39. Final reaction Ag-Cu Alloy 1 Ag-Sn Alloy Ag-Sn Alloy 2  Sn8Hg + Ag-Cu Cu6Sn5 + Ag2Hg3 + Ag-Cu 1
  • 40. Single Composition High-Copper Alloys Ag-Sn Alloy Ag-Sn Alloy Ag-Sn Alloy 1       Ag3Sn + Cu3Sn + Hg  Ag2Hg3 + Cu6Sn5 + Ag3Sn + Cu3Sn 1
  • 41. Manufacturing Process Lathe-cut alloys  Ag & Sn melted together  alloy cooled  phases solidify  heat treat  400 ºC for 8 hours  grind, then mill to 25 - 50 microns  heat treat to release stresses of grinding
  • 42. Manufacturing Process Spherical alloys  Atomizing process produces these different shapes.  First liquefying the amalgam alloy, it is sprayed through a jet nozzle under high pressure in a cold atmosphere.  If particles are allowed to cool before they contact the surface of chamber, they are spherical in shape.  If they are allowed to cool on contact with the surface they are flake shaped.
  • 43. PROPERTIES: ADA specification No.1 for amalgam lists following physical properties as a measure of quality of the amalgam.  Creep  Compressive strength  Dimensional changes  Modulus of elasticity
  • 44. Strength Compressive strength  Amalgam is strongest in compression and weaker in tension and shear  The prepared cavity design and manipulation should allow for the restoration to receive compression forces and minimum tension and shear forces.  The compressive strength of a satisfactory amalgam restoration should be atleast 310 MPa.
  • 45. Compressive Strengths of Low-Copper and High Copper Amalgam Amalgam Compressive Strength (MPa) 1 h 7 day Low copper 145 343 Admix 137 431 Single Composition 262 510
  • 46. Tensile strength  Amalgam is much weaker in tension  Tensile strengths of amalgam are only a fraction of their compressive strengths  Cavity design should be constructed to reduce tensile stresses resulting from biting forces  High early tensile strengths are important – resist fracture by prematurely applied biting forces
  • 47. Product Tensile strength (Mpa) 15min 7 days LOW COPPER ALLOYS a) Lathe cut b) spherical 3.2 51 4.7 55 HIGH COPPER ALLOYS a) Admixed b) Unicompositional 3.0 43 8.5 56 Tensile strengths of amalgam
  • 48. The factors affecting strength of amalgam are: 1) Temperature:  Amalgam looses 15% of its strength when its temperature is elevated from room temperature to mouth temperature  looses 50% of room temperature strength when temperature is elevated to 60OC e.g. hot coffee or soup.
  • 49. 2) Trituration:  Effect of trituration on strength depends on the type of amalgam alloy, the trituration time and the speed of the amalgamator.  Either, under trituration or over-trituration decreases the strength for both traditional and high copper amalgams.  More the trituration energy used, more evenly distributed are the matrix crystals over the amalgam mix and consequently more the strength pattern in the restoration.  Excess trituration after formation of matrix crystals will create cracks in the crystals, lead to drop in strength of set amalgam
  • 50. 3) Mercury Content:  Low mercury alloy content, contain stronger alloy particles and less of the weaker matrix phase, therefore more strength  Mercury is too less -- dry, granular mix, results in a rough, pitted surface that invites corrosion.  If mercury content of amalgam mix is more than 53-55%, causes drop of compressive strength by 50%.
  • 51. 4) Effect of condensation:  For lathe-cut alloys Greater the condensation pressure, the higher the compressive strength Higher condensation pressure is required to minimize porosity and to express mercury from lathe-cut amalgam.  For spherical alloys Amalgams condensed with lighter pressure produce adequate strength.
  • 52. 5) Effect of Porosity:  Can be due to  Under trituration, Particle shape, Insertion of too large increments into the cavity, Delayed insertion after trituration,  Non-plastic mass of amalgam.  Facilitate stress concentration, propagation of cracks, corrosion, and fatigue failure of amalgam restoration.
  • 53. 6) Effect of rate hardening  Patient may be dismissed from the dental chair within 20 min, rate of hardening of the amalgam is of considerable interset  At the end of 20 min, compressive strength – 6% of the 1 week strength  ADA specification stipulates minimum compressive strength of 80 Mpa at 1 hr  Clinical significance -- Patient should be cautioned not to subject the restoration for high biting force for 8 hrs after placement– 70% of its strength is gained
  • 54. Modulus of elasticity  High copper alloys tend to be stiffer than low copper alloys  When rate of loading increased, values of approx 62 Gpa have been obtained
  • 56. DIMENSIONAL CHANGES:  When mercury is combined with amalgam it undergoes three distinct dimensional changes.  Stage -1: Initial contraction, occurs for about 20 minutes after beginning of trituration. Contraction results as the alloy particles dissolve in mercury. Contraction, which occurs, is no greater than 4.5 µcm.  Stage -2: Expansion- this occurs due to formation and growth of the crystal matrix around the unconsumed alloy particles.  Stage -3: Limited delayed contraction.
  • 57. Factors that affect the dimensional changes: 1) Particle size and shape:  More regular the particle shape, more smoother the surface area.  Faster and more effectively the mercury can wet the powder particles and faster amalgamation occurs in all stages with no apparent expansion. 2) Mercury:  More mercury , more will be the expansion, as more crystals will grow.  Low mercury: alloy ratio favors contraction
  • 58. 3) Manipulation:  During trituration, if more energy is used for manipulation, the smaller the particles will become , mercury will be pushed between the particles, discouraging expansion.  More the condensation pressure used during condensation, closer the particles are brought together; more mercury is expressed out of mix inducing more contraction.
  • 59. Moisture contamination (Delayed Expansion):  Certain zinc containing low copper or high copper amalgam alloys which get contaminated by moisture during manipulation results in delayed expansion or secondary expansion  Occur 3-5 days after insertion and continues for months.  Zinc reacts with water, forming zinc oxide and hydrogen gases.
  • 60. Complications that may result due to delayed expansion are:  Protrusion of the entire restoration out of the cavity.  Increased micro leakage space around the restoration.  Restoration perforations.  Increased flow and creep.  Pulpal pressure pain. Such pain may be experienced 10-12 days after the insertion of the restoration
  • 61. Flow and Creep:  Time dependent plastic deformation  When a metal is placed under stress, it will undergo plastic deformation.  The high copper alloys, as compared with conventional silver tin alloys, usually tend to have lower creep values.
  • 62. 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 act as barrier to deformation of 1 phase.
  • 63. B) Manipulations:  Greater compressive strength will minimize creep rates.  Low mercury: alloy ratio, greater the condensation pressure and time of trituration, will decrease the creep rate.
  • 64. Corrosion Excessive corrosion can lead to:  Increased porosity.  Reduced marginal integrity.  Loss of strength.  Release of metallic products in to the oral environment.
  • 65. Phases in decreasing order of corrosion resistance  Ag2Hg3  Ag3Sn,  Ag-Cu  Cu3Sn  Cu6Sn5  Sn7-8Hg.
  • 66. Low copper amalgam system:-  Most corrodible phase is tin-mercury or 2 phase.  Neither the  nor the 1 phase is corroded as easily.  The corrosion results in the formation of tin oxychloride, from the tin in 2 and also liberates Hg. Sn7-8Hg + 1/202 + H2O + Cl- Sn4 (OH) 6 Cl2 + Hg Tin oxychloride
  • 67.  Reaction of the liberated mercury with unreacted  can produce additional l and 2 (Mercuroscopic Expansion).  Results in porosity and lower strength.
  • 68. The high copper admixed and unicomposition alloy :-  Do not have any 2 phase in the final set mass  The η phase formed has better corrosion resistance.  However,  is the least corrosion resistant phase in high copper amalgam  Corrosion product CuCl2.3Cu (OH)2 has been associated with storage of amalgams in synthetic saliva. Cu6Sn5 + 1/202 +H2O + Cl- CuCl2.3Cu (OH)2 + SnO.
  • 69. Types of Corrosion: 1) Galvanic corrosion: Dental amalgam is in direct contact with an adjacent metallic restoration such as gold crown 2) Crevice Corrosion:  Local electrochemical cells may arise whenever a portion of amalgam is covered by plaque on soft tissue.  The covered area has a lower oxygen and higher hydrogen ion concentration making it behave anodically and corrode.
  • 70. Stress Corrosion:  Regions within the dental amalgam that are under stress display a greater probability for corrosion, thus resulting in stress corrosion.  For occlusal dental amalgam greatest combination of stress and corrosion occurs along the margins.
  • 72. PROPORTIONS OF ALLOY TO MERCURY  Correct proportioning of alloy and mercury- essential for forming a suitable mass of amalgam  Some alloys require mercury – alloy ratios in excess of 1:1 (Eames technique)  whereas others use ratios of less than 1:1 with the percentage of mercury varying from 43% to 54%.
  • 73.  Automatic mechanical dispensers for alloy & mercury have been used in the past  Capsules with pre proportioned amounts of alloy & mercury have been substituted
  • 74. Cross section sketch of a disposable capsule containing amalgam alloy & mercury
  • 75. SIZE OF MIX  Manufacturers commonly supply capsules containing 400, 600, or 800 mg of alloy and the appropriate amount of mercury.  For large size cavities - capsules containing 1200 mg of all0y are also available.
  • 76. TRITURATION  Process of mixing the amalgam alloy particles with mercury  Originally, the alloy and mercury were mixed, and was triturated by hand with a mortar and pestle  Mechanical amalgamation saves time and standardizes the procedure.
  • 78. Mechanical amalgamators are available in the following speeds:  Low speed: 32-3400 cpm.  Medium speed: 37-3800 cpm.  High speed: 40-4400 cpm.  Spherical/irregular low-copper alloys – triturated at low speed  High copper alloys – high speed  Time of trituration on amalgamation ranges from 3-30 seconds. Variations in 2-3 seconds can also produce a under or over mixed mass.
  • 79.  Over-trituration: Alloy will be hot, hard to remove from the capsule, shiny wet and soft.  Under-trituration: Alloy will be dry, dull and crumbly; will crumble if dropped from approx 30 cm.  Normal Mix: Shiny appearance separates in a single mass from the capsule. Under-trituration Normal Mix
  • 80. Objectives of Trituration are:  To achieve a workable mass of amalgam within a minimum time  To remove the oxide layer  To pulverize pellets into particles, that can be easily attacked by the mercury.  To reduce particle size  To keep the amount of 1 or 2 matrix crystal as minimal as possible, yet evenly distributed
  • 81. Mixing variables 1) Working time & dimensional change All types of amalgam, spherical or irregular – decreases with overtrituration Overtrituration – slightly higher contraction for all types of alloys
  • 82. 2) Compressive & tensile strength  Irregular shaped alloys – increase by overtrituration  Spherical alloys -- greatest at normal trituration time
  • 83. 3) Creep  Overtrituration increases creep  Undertrituration lowers it
  • 84. Condensation  Refers to the incremental placement of the amalgam into the prepared cavity and compression of each increment into the others  Amalgam should be condensed into the cavity within 3 min after trituration.
  • 85. Aims of condensation  Adapt amalgam to the margins, walls and line angles of the cavity.  Minimize voids and layering between increments within the amalgam.  Develop maximum physical properties.  Remove excess mercury to leave an optimal alloy: mercury ratio.
  • 86. Purpose of Condensation  To get a continuous homogenous mass that is well adapted to all margins, walls and line angles.  Best carried out using hand instruments.
  • 87. Hand condenser :  Should allows a operator to readily grasp it & exert a force of condensation  Size of condenser tip & direction & magnitude of the force placed, depends on the type of amalgam alloy selected
  • 88.  Irregular shaped alloys – Condensers with relatively small tip, 1 to 2 mm High condensation forces in vertical direction As much mercury-rich mass as possible should be removed  Spherical amalgam alloys Condensers with large tips are used Condensed in lateral direction High copper spherical amalgams – vertical & lateral direction condensation with vibration  Condensation pressure – load of 15 lb is recommended to be applied to each increment
  • 89. Mechanical Condensers:  Useful for condensing irregular shaped alloys when high condensation forces are required  Need was eliminated with the advent of spherical alloys  Tend to lead to unreliable condensation as well as generation of heat and mercury vapor, both of which are undesirable.
  • 90. Ultrasonic Condensers:  Not recommended  Causes the release of considerable quantities of mercury vapor in the dental office
  • 91. SPEED OF PLACEMENT  Once amalgam is triturated, phase formation commences and the setting reaction is underway.  Amalgam must be placed in a plastic state  No amalgam should 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.
  • 92. 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.
  • 93. 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.
  • 94. 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.
  • 95. 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.
  • 96. 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
  • 97. 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).
  • 98. 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
  • 99.  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.
  • 101. Primary retention form Attained by:  Mechanical locking of inserted amalgam into surface irregularities to allow good adaptation  Preparation of vertical walls that converge occlusally
  • 102. Primary resistance form  For tooth : Maintaining as much unprepared tooth structure as possible Having pulpal & gingival walls perpendicular to occlusal forces Having rounded internal prepartaion angles Removing unsupported & weakened tooth structure  Placing pins into the tooth as a part of final stage of tooth preparation
  • 103. Primary resistance form  For amalgam :  Adequate thickness – 1.5 -2 mm in areas of occlusal contact, 0.75 mm in axial areas Marginal amalgam of 90 degrees or greater Box like preparation form  Rounded axiopulpal line angles in class II preparations
  • 104. Secondary resistance & retention form  When insufficient resistance/retention forms are present in tooth, additional preparation is indicated  Such features include :  Placement of grooves, locks, coves, pins, slots or amalgam pins  Larger the tooth preparation, greater the need of secondary resistance & retention forms
  • 106.  Amalgams have been used for 150 years  About 200 million amalgams are inserted each year in the United States and Europe  Concern -- mercury in dental amalgam may pose threats to the health of patients, to the health of dental care providers and to the environment.
  • 107. Mercury is available in 3 forms:  Elemental mercury (liquid or vapor).  Inorganic compounds.  Organic compounds.
  • 108.  ELEMENTAL MERCURY Liquid mercury:  Absorbed relatively poorly across skin or mucosa. Most mercury becomes charged (ionized) before it reaches the blood. Ionized mercury is excreted well through kidneys and urine. There is no known risk to patients from liquid mercury.
  • 109.  ELEMENTAL MERCURY Mercury vapor: Less benign -- rapidly absorbed into the blood via the lungs , remains uncharged and therefore highly lipid soluble, for several minutes. Can cross the blood-brain barrier where it becomes charged and exists in extra cellular fluid of the brain and returns into the blood much more slowly.
  • 110.  High tissue levels- can lead to impaired brain function, insanity and death may occur at 4000 g/kg.  Low tissue levels- can lead to restlessness, tremors, and loss of concentration.
  • 111. Inorganic compounds of mercury  S0urce – Drinking water, food  Amalgam contains several different inorganic mercury compounds,  They are of low or very low toxicity and are apparently harmless when swallowed.  Poorly absorbed, do not accumulate in body tissues and are well excreted.
  • 112. Organic compounds of mercury  Source -- Drinking water, food (sea food)  Some organic compounds of mercury are highly toxic at low concentrations  But none are known to form in the oral environment through dental amalgam use.
  • 113. Source g Hg vapour g inorganic Hg g methyl Hg Atmosphere 0.12 0.038 0.034 Drinking Water --- 0.05 --- Food & Fish 0.94 --- 3.76 Food & Non-Fish --- 20.00 --- ESTIMATED DAILY INTAKE OF MERCURY
  • 114. CONCENTRATIONS OF MERCURY  The Occupational Safety & Health Administration (OSHA) has set a TLV of 0.05 mg/m3 as the maximum amount of mercury vapor allowed in the work place.  Average Daily dose of mercury from dental amalgam for patients with more than 12 restored surfaces has been estimated at up to 3 g.
  • 115. CONCENTRATIONS OF MERCURY Clarkson TW (1997) --  Lowest dose of mercury that elicits a toxic reaction – 3to7 g/kg body weight  Paresthesia -- 500 g/kg body weight  Ataxia -- 1000 g/kg body weight  Joint pain -- 2000 g/kg body weight  Hearing loss & death -- 4000 g/kg body weight
  • 116. CONCENTRATIONS OF MERCURY Mercury release has been quantified for a number of procedures:  Trituration: 1-2g  Placement of amalgam restoration: 6-8 g.  Dry polishing: 44 g.  Wet polishing: 2-4 g.  Amalgam removal under water spray & high velocity suction: 15-20 g
  • 117. CONCENTRATIONS OF MERCURY 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 passivating surface oxide film-although this re-forms rapidly.
  • 118. Mercury in urine  Body cannot retain metallic mercury, but passes it through urine  Skare I et al (1990) – urine mercury level peak at 2.54 g/L 4 days after placing amalgam restorations, return to zero after 7 days On removal of amalgam, urine mercury levels reach a maximum value of 4g/L, return to zero after 7 days
  • 119. Mercury in blood  Maximum allowable level of mercury in blood is 3 g/L  Chang SB et al(1992) showed that freshly placed amalgam restorations elevated blood mercury levels to 1 to 2 g/L  As with urine mercury levels, there is first an increase of around 1.5 g/L, which decreases in about 3 days
  • 120.  Ott KH et al (1996) monitored blood mercury levels for 1 year, showed that patients with amalgams had lower than average blood mercury level (0.6 g/L ) than patients without amalgams (0.8 g/L )  Mackert JR et al(1997) indicated higher blood mercury levels in dentists, stated that -  elevated blood mercury levels may relate to mercury spills in the office Both blood & serum mercury levels seem to correlate best with occupational exposure, not with number of amalgam & length of time with amalgam in place
  • 121. BIO-COMPATIBILITY –MERCURY TOXICITY Sensitivity to amalgam restorations  Skin lesions being more common than oral lesions.  An urticarial rash may appear on the face and limbs and this may be followed by dermatitis.  Long- term response -- oral lichen planus or lichenoid reactions with erosive areas on the tongue or buccal mucosa adjacent to an amalgam restoration.
  • 123. AMALGAM TATTOO Possible causes are:  Scraps of amalgam may fall into open surgical or extraction wounds.  Excess amalgam may be left in the tissues following sealing the apex of a root canal with a retrograde amalgam.  Pieces of amalgam may be forced into the mucosa.
  • 124. Sources of Mercury Exposure in Dental Office:  Dental amalgam raw materials being stored for use.  Mixed but unhardened dental amalgam during triturations, insertion and intraoral setting.  Dental amalgam scrap that has insufficient alloy to completely consume the mercury present.  Dental amalgam undergoing finishing and polishing procedure.  Dental amalgam restoration being removed.
  • 125. DENTAL MERCURY HYGIENE Recommendations from the ADA include the following:  The work place should be well ventilated, with fresh air exchange and outside exhaust  Use only precapsulated alloy, discontinue use of Bulk mercury & bulk alloy  Avoid the need to remove excess mercury before or during packing by selecting an appropriate alloy: mercury ratio  Use an amalgamator with a completely enclosed arm.
  • 126.  Mercury and unset amalgam should not be touched by the bare hands.  Floor coverings should be non absorbent & easy to clean  Spilled mercury should be cleaned up using trap bottles, tape or freshly mixed amalgam to pick up droplets  Do not use a house hold vaccum cleaner to clean spilled mercury.  Skin accidentally contaminated by mercury should be washed thoroughly with soap and water.
  • 127.  If a mercury hygiene problem is suspected, personnel should undergo urine analysis to detect mercury levels  Remove professional clothing before leaving the work place
  • 128. Scrap amalgam disposal  In a tightly closed container  Under radiographic fixer solution  Dispose mercury contaminated items in sealed bags  Donot dispose mercury contaminated items in medical waste containers or bags or along with the waste that will be incenerated
  • 129. CLINICAL TECHIQUES TO ENHANCE MARGINAL SEAL 1) Copal resin varnish:  Apply two thick coats to the cavity walls and margins before placing the amalgam and it will gradually dissolve, beginning at the cavosurface, over 2-3 months.  As the varnish dissolves out, the gap will be filled with corrosion products from the amalgam and dissolution of the varnish will cease.
  • 130. CLINICAL TECHIQUES TO ENHANCE MARGINAL SEAL 2) Glass-ionomer linings  Placed under an amalgam will seal the dentinal tubules and release small quantities of fluoride  Will not affect enamel margins or enhance the seal at the margin.
  • 131. CLINICAL TECHIQUES TO ENHANCE MARGINAL SEAL 3) Oxalate solutions :  Such as potassium oxalate, can be applied to the cavity surface to reduce the permeability of the tubules and possibly seal the dentine.  The crystals this deposited will not wash out but will allow deposition of corrosion products.
  • 132. RECENT ADVANCES 1) BONDED AMALGAMS  During the 1990’s some clinicians began to routinely bond amalgam restorations to enamel and dentine  After preparation of the cavity, enamel and dentine etched using a conventional etchant, a chemically cured resin-bonding agent applied to the walls of the cavity.  Amalgam is immediately condensed into the cavity before the resin bond has cured
  • 133. Advantages of Bonded-Amalgam :  Conservation of tooth structure.  Fracture strength was as high as for composites  Decreased marginal leakage in class 5 restorations compared with unbonded amalgams  Some operators claim elimination of post-insertion sensitivity.  Reduces incidence of marginal fracture and recurrent caries.  Can be done in single sitting.  Allows for amalgam repairs.
  • 134. Disadvantages of Bonded-Amalgam :  Clinical difficulty of application of more viscous bonding agents  Lightly filled resin bonding agents tend to pool at the gingival margin resulting in a higher potential for micro leakage.  Carving is difficult.  Requires practitioner to adapt to new technique.  Increases cost of amalgam restorations.
  • 135. 2) Gallium alloys  Mercury free metallic restorative materials proposed as substitute for mercury containing amalgam are gallium containing materials and pure silver and/or silver based alloys  Puttkammer (1928), suggested the use of gallium in dental restoration  Attempts to develop satisfactory gallium restorative materials were unsuccessful until Smith et al in 1956, showed that improved Pd-Ga and Ag-Ga materials has physical and mechanical properties that were similar to or even better than those of silver amalgam.
  • 136. ADVANTAGES OF GALLIUM BASED ALLOYS:  Rapid solidification.  Good marginal seal by expanding on solidification.  Heat resistant.  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
  • 137. REACTION : Ag3Sn + Ga  Ag3Ga + Sn.
  • 138. REACTION :  After mixing, the alloy tends to adhere to the walls of capsule, thus difficult to handle.  Moreover, by adding few drops of alcohol, the problem of sticking can be minimized.
  • 139. Biologic considerations of Gallium based alloys :  Surface roughness, marginal discoloration and fracture were reported. With improvement in composition, these defects were reduced but not eliminated  Could not be used in larger restorations as the considerable setting amount of expansion leads to fracture of cusps and post operative sensitivity.  Cleaning of instruments tips is also difficult  Less popular because it is costlier than amalgam.
  • 140. 3) Fluoride releasing amalgam  Have been shown to have anticaries properties sufficient to inhibit the development of caries in cavity walls.  Concentration of fluoride is sufficient to enhance remineralization  Tviet and Lindh (1980) -- greatest concentration of fluoride i.e. about 4000µg/mL in enamel surfaces exposed to fluoride-containing amalgams were found in the outer 0.05µm of the tissue.
  • 141.  In dentin, the greatest concentrations, i.e. about 9000µg/ml were found at a depth of 11.5µm.  However, this release of fluoride decreases to minor amounts after 1 week.  Forsten L (1976) -- fluoride released from amalgams loaded with soluble fluoride salts was detectable within the first month and thereafter fluoride was not released in measurable amounts.  Garcia Godoy et al( 1990) – fluoride release can continue as long as 2 years (but at a much lower rate than that for GIC).
  • 142. Marginal fracture of amalgam  Referred to as “Marginal breakdown”, “ditching”, and “crevice formation”.  Regardless of the type of amalgam, marginal fracture increases with time  The rate of increase is greater for low-copper amalgams.
  • 143. CLINICAL TECHNIQUES TO PREVENT MARGINAL FRACTURE  Excess amalgam, left lying over the occlusal or proximal surface should be carved correctly  The angle of the carvo-surface margin should be greater than 70º and the cavity should be designed to allow for this.  On completion of packing, burnish the margins both before and after carving to improve marginal adaptation.
  • 144. Repair Of Amalgam Restorations  When an amalgam restoration fails, as from marginal fracture, it is repaired  A new mix of amalgam is condensed against the remaining part of the existing restoration  The strength of the bond between the new and the old amalgam is important
  • 145. Factors contributing to strength of repair  Presence of porosity and  phase at the junction.  Inadequate condensation.  Contamination of the surface of the existing amalgam.  Corrosion & contamination from saliva.
  • 146. CLINICAL CONSIDERATIONS Marginal Adaptation And Seal :  Lack of marginal adaptation in first few weeks  May be associated with marginal deterioration, accumulation of debris, recurrent caries, post- restoration sensitivity or pulpal reactions.
  • 147. CLINICAL CONSIDERATIONS Self-Sealing :  After 48 hours, “self sealing” occurs  Low-copper amalgam -- seal within 2-3 months  High-copper amalgams -- corrode less and therefore take 10-12 months to provide a comparable seal.
  • 148. Amalgam wars  In 1845, American Society of Dental Surgeons condemned the use of all filling material other than gold as toxic, thereby igniting "first amalgam war'. The society went further and requested members to sign a pledge refusing to use amalgam.  In mid 1920's a German dentist, Professor A. Stock started the so called "second amalgam war". He claimed to have evidence showing that mercury could be absorbed from dental amalgam, which leads to serious health problems. He also expressed concerns over health of dentists, stating that nearly all dentists had excess mercury in their urine.
  • 149. Amalgam wars  "Third Amalgam War' began in 1980 primarily through the seminars and writings of Dr.Huggins, a practicing dentist in Colorado.  He was convinced that mercury released from dental amalgam was responsible for human diseases affecting the cardiovascular system and nervous system  Also stated that patients claimed recoveries from multiple sclerosis, Alzheimer’s disease and other diseases as a result of removing their dental amalgam fillings.
  • 150. CONCLUSION There are certain advantages inherent with amalgam such as technique insensitive, excellent wear resistance, less time consuming, less expensive which are not present in the newer materials, these factors will continue to make amalgam the material of choice for many more years to come.
  • 151. 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.  Craig, “Science of Dental Materials”.  Jagannathan, K, “Cruise for Gamma 2 Free Mercury”, “Materials in Restorative Dentistry”, MADC & H, 1998 66-69.  John F. McCabe, Angus W.G. Walls, “Dental Amalgam”, Applied Dental Materials, Blackwell Science, 8th Edition, 1998:157-168  Satish Chandra, Shaleen Chandra, “Dental Amalgam”, A Text Book of Dental materials with Multiple Choice Questions”, Jaypee Brothers; 1st Edition 2000.  Vimal. K. Sikri, “Silver Amalgam”, Text book of Operative Dentistry” CBS publishers, 1st Edition 2002, 204-242.