AMALGAM AMALGAM RESTORATIONSRESTORATIONS

))11( ( DEFINITION OF DENTAL DEFINITION OF DENTAL AMALGAMAMALGAM

It is the combination of dental amalgam alloy It is the combination of dental amalgam alloy composed of silver, tin and copper with composed of silver, tin and copper with

mercury (sometimes it contains zincmercury (sometimes it contains zinc(.(.

DEFINITION OF AMALGAMATION DEFINITION OF AMALGAMATION PROCESSPROCESS

It is the process of alloying of mercury being in It is the process of alloying of mercury being in liquid state to Ag-Sn metal alloy being in the liquid state to Ag-Sn metal alloy being in the

solid statesolid state. .

))II( TYPES OF AMALGAMII( TYPES OF AMALGAM 11( ( According to copper contentAccording to copper content::

11-- Conventional amalgam (Cu is less than 6%Conventional amalgam (Cu is less than 6%(( 22-- High copper amalgam (Non-∂ 2 amalgam( (Cu is High copper amalgam (Non-∂ 2 amalgam( (Cu is

more than 6%more than 6%(.(.

22( ( According to Zinc contentAccording to Zinc content:: 11- - Zinc containing amalgamZinc containing amalgam..

22-- Zink- free amalgamZink- free amalgam..When zinc comes in contact with moisture (saliva( When zinc comes in contact with moisture (saliva( delayed 2delayed 2ndryndry expansion will occur expansion will occur..

Zn + HZn + H22O ZnO + HO ZnO + H22

CLINICAL EFFECT OF CLINICAL EFFECT OF MOISTUREMOISTURE

11- - Secondary delayed expansionSecondary delayed expansion..

22-- Delayed painDelayed pain..

33-- Overhanging marginsOverhanging margins..

44-- Recurrence of decayRecurrence of decay..

55-- Weak & corrodible amalgamWeak & corrodible amalgam. .

ACCORDING TO PARTICLES SHAPEACCORDING TO PARTICLES SHAPE

11-- Lathe – cut alloy particles [Irregular Lathe – cut alloy particles [Irregular shape needles shape needles[.[.

22- - Spherical alloy particles. [Particles Spherical alloy particles. [Particles are rounded or spherical in shape are rounded or spherical in shape[[

33- - Admixed alloy particlesAdmixed alloy particles..

Lath-cutLath-cut

Spherical all0ySpherical all0y

Admixed alloyAdmixed alloy

))11( ( IN CASE OF THE LATHE-CUT TYPE: IN CASE OF THE LATHE-CUT TYPE: METHOD OF MANUFACTURINGMETHOD OF MANUFACTURING::

All the alloy ingredients are melted All the alloy ingredients are melted forming an ingot (cast( then after cooling forming an ingot (cast( then after cooling & solidification, we subject the ingot to a & solidification, we subject the ingot to a milling machine & so, we get fillings, milling machine & so, we get fillings,

needle shaped typeneedle shaped type..

))22( ( IN CASE OF THE SPHERICAL IN CASE OF THE SPHERICAL ALLOY PARTICLES: METHOD OF ALLOY PARTICLES: METHOD OF

MANUFACTURINGMANUFACTURING::

Pour the melted ingot into an inert gas Pour the melted ingot into an inert gas

chamber (Nchamber (N22 gas( [no O gas( [no O22 to prevent the to prevent the

oxidation[ by spraying [Atomization[ when oxidation[ by spraying [Atomization[ when they are sprayed by inert gas upon they are sprayed by inert gas upon solidification, they will solidify in the form of solidification, they will solidify in the form of

spheresspheres..

))33( ( IN CASE OF THE ADMIXED TYPEIN CASE OF THE ADMIXED TYPE::

They manufacture lathe-cut alone They manufacture lathe-cut alone & spherical alone & then they are & spherical alone & then they are mixed togethermixed together..

))44( ( ACCORDING TO PARTICLE SIZEACCORDING TO PARTICLE SIZE::

11-- Micro-cut alloy particleMicro-cut alloy particle..

22-- Fine-cut alloy particleFine-cut alloy particle..

33-- Coarse-cut alloy particleCoarse-cut alloy particle..

The best form is theThe best form is the Fine-cutFine-cut . .

SHERICAL AMALGAM ALLOY SHERICAL AMALGAM ALLOY PARTICLES CHARACTARISTICSPARTICLES CHARACTARISTICS::

11-- Zinc content not requiredZinc content not required..

22-- Less amount of Hg is neededLess amount of Hg is needed..

33- - Amalgamates more easilyAmalgamates more easily..

44-- Less technique sensitive (advLess technique sensitive (adv.(..(.

55-- Increased early compressive strengthIncreased early compressive strength..

66-- Easier to condense, carve & polishEasier to condense, carve & polish..

MICRO-CUT AMALGAM ALLOY PARTICLESMICRO-CUT AMALGAM ALLOY PARTICLES

less than 10 micronsless than 10 microns

* * CHARACTARISTICSCHARACTARISTICS : :

-- Greater amount of Hg required (Greater S.A: Greater amount of Hg required (Greater S.A: Surface appear granular Surface appear granular( .( .

-- Less plastic massLess plastic mass..

-- Decreased compressive strengthDecreased compressive strength. .

FINE-CUT AMALGAM ALLOYFINE-CUT AMALGAM ALLOY

particles [10-30 micronsparticles [10-30 microns[[

* * CHARACTARISTICSCHARACTARISTICS : :

- - Improved adaptationImproved adaptation..

- - Smoother surface textureSmoother surface texture..

- - Easier carving & polishingEasier carving & polishing..

- - Increased compressive strengthIncreased compressive strength..

COARSE-CUT AMALGAM ALLOY PARTICLESCOARSE-CUT AMALGAM ALLOY PARTICLES

[ [Greater than 30 micronsGreater than 30 microns[.[.

* * CHARACTARISTICSCHARACTARISTICS : :

- - Less amount of Hg required (adv but as Less amount of Hg required (adv but as particles are rough & large less adaptation particles are rough & large less adaptation((

- - Rough surface textureRough surface texture..

- - Decreased adaptation to cavity wallsDecreased adaptation to cavity walls..

- - Increased compressive strengthIncreased compressive strength. .

]]III] COMPOSITION OF AMALGAM ALLOYIII] COMPOSITION OF AMALGAM ALLOY

11-- Conventional alloy (TraditionalConventional alloy (Traditional(.(.

22-- High-Cu alloy (non-High-Cu alloy (non-σσ 2 amalgam 2 amalgam((

))11(*(*COMPOSITION OF CONVENTIONAL COMPOSITION OF CONVENTIONAL SILVER/ TIN AMALGAM ALLOYSILVER/ TIN AMALGAM ALLOY::

** SilverSilver : not less than: not less than 65% by wt 65% by wt..

** Tin Tin : not less than: not less than 25% by wt 25% by wt..

** CopperCopper: : not more thannot more than 6% by wt 6% by wt..

** ZincZinc : : not more thannot more than 2% by wt 2% by wt..

** SilverSilver : : It is the main ingredient of amalgam It is the main ingredient of amalgam used toused to::

- - strength & hardness of amalgamstrength & hardness of amalgam..

- - flowflow..

- - Some expansionSome expansion..

* * Tin:Tin: tin is introduced to give tin is introduced to give plasticity of mass as tin has a great affinity to Hg plasticity of mass as tin has a great affinity to Hg so. It is attracted to Hg & so it gives plasticity to so. It is attracted to Hg & so it gives plasticity to mass allows amalgamation process to take place mass allows amalgamation process to take place easilyeasily

** StrengthStrength

* * FlowFlow

* * Cause contractionCause contraction

**Copper: )like AgCopper: )like Ag((

** strengthstrength

* * flowflow

** produces expansionproduces expansion

** Improves setting characteristicsImproves setting characteristics..

* * ZincZinc:: Acts as a scavenger or deoxidizer duringActs as a scavenger or deoxidizer during

manufacturingmanufacturing..

It prevents the formation of oxides on It prevents the formation of oxides on Cu, Ag & Sn Cu, Ag & Sn..

Disadv.:Disadv.: if amalgam is applied below free if amalgam is applied below free gum margin , moisture contamination will gum margin , moisture contamination will cause excessive delayed secondary cause excessive delayed secondary expansion ( 3-5 days after placement of expansion ( 3-5 days after placement of

restorationrestoration(.(.

* * Reaction of conventional amalgamReaction of conventional amalgam:: It is a crystallization reactionIt is a crystallization reaction::

AgAg33 + Hg Ag + Hg Ag22HgHg33 + Sn + Sn77Hg + AgHg + Ag33SnSn..

σσ + Hg + Hg σσ11 + + σσ 22 + unreacted + unreacted σσ

intermediate weakest strongestintermediate weakest strongest

strength phase phasestrength phase phase

- - The strongest phase is The strongest phase is σσ , it gives , it gives very strong amalgam restoration very strong amalgam restoration followed by followed by σσ11then the weakest phase then the weakest phase

is is σσ22 which is susceptible to which is susceptible to

corrosioncorrosion..

- - We have to eliminate Sn-Hg phase We have to eliminate Sn-Hg phase as much as possible to avoid weak as much as possible to avoid weak amalgam restorationamalgam restoration..

))22( ( COMPOSITION OF HIGH COPPER COMPOSITION OF HIGH COPPER AMALGAM ALLOYAMALGAM ALLOY::

** Silver Silver : not less than 40% : not less than 40%

** TinTin : not less than 25% : not less than 25%

* * CopperCopper : 10 – 30% : 10 – 30%

** Zinc Zinc : 0-2% : 0-2%

- - We cannot remove tin from the ingredients We cannot remove tin from the ingredients otherwise amalgam will be granular otherwise amalgam will be granular..

- - The increase in the % of copper is on the The increase in the % of copper is on the expense of Ag expense of Ag..

** ** CHARACTARISTICS OF HIGH CHARACTARISTICS OF HIGH COPPER AMALGAMCOPPER AMALGAM::

))11(( Higher early compressive strengthHigher early compressive strength..

))22(( Increased corrosion resistanceIncreased corrosion resistance..

))33(( Improved marginal integrityImproved marginal integrity

))44(( Lower creep valueLower creep value

** ** TYPES OF HIGH COPPER TYPES OF HIGH COPPER AMALGAMAMALGAM::

))11(( Admixed ( Lathe cut + SphericalAdmixed ( Lathe cut + Spherical((

))22(( Single composition (Spherical or Single composition (Spherical or Lathe –cut Lathe –cut((

))11( ( Admixed high copper amalgamAdmixed high copper amalgam::

* * CompositionComposition:: 10-20%10-20% coppercopper

-- it is called Admixed type because some it is called Admixed type because some particles are spherical & some are lathe- particles are spherical & some are lathe- cut cut..

- - 2/32/3 lathe-cutlathe-cut..

- - 1/31/3 spherical Ag-Cu (eutectic phasespherical Ag-Cu (eutectic phase(.(.

* * ReactionReaction : Mercury will penetrate bet. The : Mercury will penetrate bet. The particles particles

** AgAg33Sn (Sn (σσ ( + Hg Ag ( + Hg Ag22HgHg33((σσ11 ( + ( +

Sn Sn77Hg (Hg (σσ22 ( + Ag ( + Ag33Sn (Sn (σσ (. (.

** SnSn77Hg (Hg (σσ22 ( + AgCu Ag ( + AgCu Ag22HgHg33 ( (σσ11 ( + ( +

Cu6Sn5(ECu6Sn5(E((

** σσ22 in the 1 in the 1stst reaction would be attacked by AgCu reaction would be attacked by AgCu

of the eutectic of the eutectic..

** Cu has a very great affinity to Sn so, it forms a Cu has a very great affinity to Sn so, it forms a

compound called Cu compound called Cu66SnSn55..

- - The aim of this reaction is: How to get rid of The aim of this reaction is: How to get rid of

AgAg33Sn but at the same time presence of Sn is Sn but at the same time presence of Sn is

v.imp as it has more affinity to Cu than Hg so, it v.imp as it has more affinity to Cu than Hg so, it will react with Cu & form E formwill react with Cu & form E form..

* * σσ2 phase is eliminated & the net result is2 phase is eliminated & the net result is::

σσ 11 + + σσ 1 1 σσ E E

Resultant is CuResultant is Cu66SnSn55 phase phase..

))22( ( Single Single COMPOSITION COMPOSITION high copper high copper amalgamamalgam ::

* * COMPOSITIONCOMPOSITION : :

13-30%13-30% coppercopper.. - - Ternary Ag-Sn-CuTernary Ag-Sn-Cu..

- - Indium or palladium 10% ( to creep & corrosion Indium or palladium 10% ( to creep & corrosion resistanceresistance((

- - it is made of one type only of alloy lathe cut or it is made of one type only of alloy lathe cut or spherical not a mixture spherical not a mixture..

- - Each alloy particle contains Ag-Sn-Cu whether itEach alloy particle contains Ag-Sn-Cu whether it.. spherical or lathe – cut this is called ternary spherical or lathe – cut this is called ternary

alloy alloy.. - - Indium corrosion resistanceIndium corrosion resistance..

* * ReactionReaction : : Ag- Sn Cu + Hg AgAg- Sn Cu + Hg Ag22HgHg33((σσ(+Cu(+Cu66SnSn55(E(E(.(.

- - Sn has more affinity to Cu than Hg So, we have Sn has more affinity to Cu than Hg So, we have no no σσ22 phase no SnHg phase as it will not leave phase no SnHg phase as it will not leave

Cu& bond with Hg Cu& bond with Hg..

))IV( PROPERTIES OF AMALGAM IV( PROPERTIES OF AMALGAM RESTORATIONRESTORATION::

AdvantagesAdvantages::

) )11(( Adequate compressive strengthAdequate compressive strength..

))22(( High abrasion resistanceHigh abrasion resistance..

))33(( Insolubility in oral fluidsInsolubility in oral fluids..

) )44(( Adaptability to cavity wallsAdaptability to cavity walls..

) )55(( Convenience of manipulationConvenience of manipulation..

) )66(( Biocompatibility with oral & dental tissuesBiocompatibility with oral & dental tissues..

DisadvantagesDisadvantages:: ]]11[[ Dimensional changesDimensional changes..

]]22[[ Creep or flow tendencyCreep or flow tendency.. ]]33[[ Inadequate tensile strengthInadequate tensile strength..

]]44[[ Low edge strengthLow edge strength.. ] ]55[[ Thermal conductivityThermal conductivity . .

]]66[[ GalvanismGalvanism.. ]]77[[ Tarnish & corrosionTarnish & corrosion..

] ]88[[ Inharmonious colorInharmonious color..If it is properly manipulated we can If it is properly manipulated we can overcome some if not all of these dis-advovercome some if not all of these dis-adv. .

]]11[ [ Dimensional changesDimensional changes::

- - Regarding the dimensional changes amalgam Regarding the dimensional changes amalgam undergoes .3 stagesundergoes .3 stages::

a( First stagesa( First stages:: When Hg is added to the alloy powder & after When Hg is added to the alloy powder & after

trituration by 10 min. Amalgam undergoes slight trituration by 10 min. Amalgam undergoes slight contraction due to the penetration of Hg into the contraction due to the penetration of Hg into the alloy particlesalloy particles..

b( Second stageb( Second stage:: After 10 min. of triturition & till the first 8 hours, After 10 min. of triturition & till the first 8 hours,

there will be sever expansion due to the formation of there will be sever expansion due to the formation of

σσ1 1 phase or silver – mercury phasephase or silver – mercury phase..

c( Third stagec( Third stage:: After 24 hours there will be very slight contraction After 24 hours there will be very slight contraction

as a result of the setting of amalgam mass, all the as a result of the setting of amalgam mass, all the phases of amalgam approach each otherphases of amalgam approach each other. .

]]22[ [ Creep or flow tendencyCreep or flow tendency::

Deformation of amalgam under loadDeformation of amalgam under load..

** CreepCreep: : Deformation of amalgam restoration Deformation of amalgam restoration under load after it has completely under load after it has completely set set..

** FlowFlow: : Deformation of amalgam restoration Deformation of amalgam restoration under load before it has set under load before it has set..

DisadvantagesDisadvantages::

11-- Flattening of contact areaFlattening of contact area..

22-- Over hangingOver hanging..

33- - Protrusion of restorationProtrusion of restoration..

]]33[ [ Inadequate tensile strengthInadequate tensile strength::

- - Amalgam can fracture at the isthmus Amalgam can fracture at the isthmus (junction bet. Occlusal & proximal (junction bet. Occlusal & proximal parts( due to its low tensile strength parts( due to its low tensile strength under tension loadunder tension load..

]]44[ [ Low edge strengthLow edge strength::

- - The low edge strength is responsible for the The low edge strength is responsible for the fracture at the margins fracture at the margins..

((11( ( Amalgam ditch can occur I.e. v-shaped Amalgam ditch can occur I.e. v-shaped groove that occurs as a result of fracture of the groove that occurs as a result of fracture of the margins of amalgam between amalgam & margins of amalgam between amalgam & cavity walls at the cavosurface margincavity walls at the cavosurface margin..

To prevent this, the cavosurface angle must be To prevent this, the cavosurface angle must be 9090oo to increase the bulk of amalgam at this area to increase the bulk of amalgam at this area

] ]55[ [ Thermal conductivityThermal conductivity: :

Amalgam can transmit thermal impulses to the Amalgam can transmit thermal impulses to the pulp & this can be overcome by putting pulp & this can be overcome by putting

cementcement..

-- In deep cavities we put a liner to protect In deep cavities we put a liner to protect pulp from Thermal conductivity pulp from Thermal conductivity..

-- In shallow cavities there is enough In shallow cavities there is enough dentin to protect pulp dentin to protect pulp..

]]66[ [ GalvanismGalvanism

- - If we have two dissimilar metals on the same If we have two dissimilar metals on the same side ex: amalgam & the other is gold, saliva acts as side ex: amalgam & the other is gold, saliva acts as the electrolyte, amalgam acts as a node & gold the electrolyte, amalgam acts as a node & gold acts as cathode so, when they come in contact acts as cathode so, when they come in contact ions are transmitted from amalgam to gold & ions are transmitted from amalgam to gold & this causes pain. As an electric current will passthis causes pain. As an electric current will pass..

- - This is associated with corrosion & it is called This is associated with corrosion & it is called galvanic corrosiongalvanic corrosion . .

]]77[ [ Tarnish & corrosionTarnish & corrosion

TarnishTarnish**It is an oxide film that causes discoloration It is an oxide film that causes discoloration

(blackening(blackening(.(.

corrosioncorrosion * * It is the disintegration of the outer surfaceIt is the disintegration of the outer surface. .

* * IndicationsIndications:: - - Class IClass I

- - Class IIClass II

- - Class vClass v

- - and distal cavities of canine in class IIIand distal cavities of canine in class III..

* * Contra IndicationContra Indication:: - - Anterior cavitiesAnterior cavities . .

- - In the presence of other metallic In the presence of other metallic restorationrestoration..

To avoid galvanismTo avoid galvanism..

]]VI[ Clinical application of VI[ Clinical application of amalgam restorationamalgam restoration

]]11[[ Cavity preparation & pulp protectionCavity preparation & pulp protection..

]]22[[ Matrix & wedge applicationMatrix & wedge application..

] ]33[[ Alloy selection & proportioningAlloy selection & proportioning . .

]]44[[ Triturition & condensationTriturition & condensation..

]]55[[ carving & burnishingcarving & burnishing..

] ]66[[ Wedge & matrix removalWedge & matrix removal..

] ]77[[ Finishing & polishingFinishing & polishing..

ManipulationManipulation

The ratio )or the alloy / mercury ratioThe ratio )or the alloy / mercury ratio(:(:

The amount of mercury needed is to coat all the The amount of mercury needed is to coat all the particles to produce homogeneous coherent particles to produce homogeneous coherent

mass of amalgammass of amalgam..

11-- Ratio 1:1 or 5:5 techniqueRatio 1:1 or 5:5 technique..

22-- Ratio 5:8 techniqueRatio 5:8 technique..

* * The ratio is by weight and not by volumeThe ratio is by weight and not by volume..

Excess mercury leads toExcess mercury leads to : :

11- - strengthstrength..

22- - Flow and creepFlow and creep..

33- - ExpansionExpansion..

44- - Tarnish and corrosionsTarnish and corrosions..

Less mercury leads toLess mercury leads to : : 11-- non-coherentnon-coherent..

22-- WeakWeak..

33-- Less resistance to tarnish and corrosionLess resistance to tarnish and corrosion.. N.B:N.B: Each in Hg by 15% results in 1.5% excess in the Each in Hg by 15% results in 1.5% excess in the final restorationfinal restoration..

Methods of proportioningMethods of proportioning:: 11-- Simple weighing balanceSimple weighing balance . .

22-- Tablets or pellets where amount of Hg Tablets or pellets where amount of Hg is measured according to the manufacture is measured according to the manufacture by a mechanical dispenser by a mechanical dispenser..

33-- Automatic mechanical dispenserAutomatic mechanical dispenser..

Dispenser should beDispenser should be

11(( clean and dryclean and dry..

22(( Vertical to obtain proper measurementVertical to obtain proper measurement. .

33(( Half filledHalf filled..

DisadvantagesDisadvantages::a)a) Some alloys can cling to the wall Some alloys can cling to the wall of the dispenser of the dispenser..

b)b) Each dispenser is for one type of Each dispenser is for one type of alloy l.e. can’t be used universally alloy l.e. can’t be used universally for all types of alloys for all types of alloys

44-- Preproportioning capsulesPreproportioning capsules (the best (the best method) proper alloy and Hg ratio is done by method) proper alloy and Hg ratio is done by manufacturing and are put in a capsulemanufacturing and are put in a capsule..

A disc or membrane separates Hg and alloy to prevent A disc or membrane separates Hg and alloy to prevent premature amalgamationpremature amalgamation..

Activation is done before trituration. This is done by Activation is done before trituration. This is done by removal of the membrane, and provide contact removal of the membrane, and provide contact between alloy and Hgbetween alloy and Hg..

This could be done byThis could be done by - Pressure- Pressure..

- - Twisting cover of capsuleTwisting cover of capsule

55-- Self-activated capsulesSelf-activated capsules:: The process of amalgamation activates the capsuleThe process of amalgamation activates the capsule

Advantages of proportioning capsuleAdvantages of proportioning capsule:: 11-- More convenientMore convenient..

22-- Proper Hg alloy ratio variables of dentists are Proper Hg alloy ratio variables of dentists are eliminated eliminated..

33-- Prevent spill of Hg preventing Hg hazardsPrevent spill of Hg preventing Hg hazards..

II- TriturationII- Trituration:: ** DefinitionDefinition::

It is the process by which the alloy and mercury It is the process by which the alloy and mercury are amalgamated together intoare amalgamated together into::

-- CoherentCoherent..

- - HomogeneousHomogeneous..

-- SmoothSmooth..

- - Plastic mass of amalgamPlastic mass of amalgam. .

* * Methods of triturationMethods of trituration::

a.a. Manual trituration using Mortar and PestleManual trituration using Mortar and Pestle..

b.b. Mechanically using electric amalgamatorMechanically using electric amalgamator..

AA.. Hand trituration Hand trituration::

i-i- Glass mortar and pestle are usedGlass mortar and pestle are used..

ii-ii-Should be cleaned to prevent contaminationShould be cleaned to prevent contamination..

iii-iii-The face of the Pestle must have the same shapeThe face of the Pestle must have the same shape as the surface of the mortar for effective triturationas the surface of the mortar for effective trituration..

iv-iv- Both Mortar and Pestle should present an even rough Both Mortar and Pestle should present an even rough working surface for effective trituration working surface for effective trituration..

v- v- The trituration process must be standardized by rate, time The trituration process must be standardized by rate, time and pressure and pressure..

e.g:e.g: 2kg or 4 kg is 1 min. In 60 revolution2kg or 4 kg is 1 min. In 60 revolution..

Aims of triturationAims of trituration.. a.a. To rub off the oxide layer on the alloy To rub off the oxide layer on the alloy

particles particles..

b.b. For further reduction of the size of the For further reduction of the size of the alloy particles alloy particles..

c.c. To bring the mercury into contact with To bring the mercury into contact with the alloy particles to start the reaction the alloy particles to start the reaction..

* * Properly triturated amalgam will appearProperly triturated amalgam will appear::

A.A. HomogeneousHomogeneous..

B.B. SmoothSmooth..

C.C. Climb along the side of the mortar and Climb along the side of the mortar and form a curl at its top form a curl at its top..

* * Under triturated leads toUnder triturated leads to::

A.A. WeakWeak..

B.B. Non-homogeneousNon-homogeneous..

C.C. Excess mercuryExcess mercury..

D.D. Appear dullAppear dull..

E.E. Non-coherentNon-coherent..

F.F. Undergo more expansionUndergo more expansion..

G.G. More tarnish and corrosionMore tarnish and corrosion..

Over triturated leads toOver triturated leads to::

A.A. Sets fasterSets faster..

B.B. Greater one hour strengthGreater one hour strength..

C.C. Smooth surfaceSmooth surface..

D.D. Less flowLess flow..

E.E. More tarnish and corrosion resistanceMore tarnish and corrosion resistance..

F.F. The only disadvantages is that it may The only disadvantages is that it may undergo contraction farther than expansion undergo contraction farther than expansion..

B. Mechanical TriturationB. Mechanical Trituration::. . This methodThis method::

11-- Saves timeSaves time..

22- - Gives better standardization, for the triturated Gives better standardization, for the triturated amalgam amalgam. .

* * Mulling of amalgamMulling of amalgam:: It is a process of mulling the properly triturated It is a process of mulling the properly triturated

amalgam for few sec. In a piece of rubber to amalgam for few sec. In a piece of rubber to acquire a max. degree of plasticityacquire a max. degree of plasticity..

II. CondensationII. Condensation:: * * DefinitionDefinition::

It is the process of packing of the properly triturated It is the process of packing of the properly triturated amalgam in the prepared cavityamalgam in the prepared cavity..

**AimsAims:: 11.. The adaptation of amalgam to cavity walls and The adaptation of amalgam to cavity walls and

margins margins..

22.. The adaptation between successive layer of The adaptation between successive layer of amalgam amalgam . .

33.. Express excess mercury and density of the alloyExpress excess mercury and density of the alloy..

44. . The compressive strength of amalgamThe compressive strength of amalgam..

* * Requirements for proper condensationRequirements for proper condensation::

11.. Only fresh mixes should be used. (Mixes more Only fresh mixes should be used. (Mixes more than 3.5min. Should be discarded, this is to than 3.5min. Should be discarded, this is to avoid layering of amalgam avoid layering of amalgam..

22.. We must use successive increments for effective We must use successive increments for effective condensation condensation..

33.. Great condensation pressure is required, Great condensation pressure is required, directed, towards cavity wall, and margins directed, towards cavity wall, and margins..

44.. Each condensed layer must be properly stable Each condensed layer must be properly stable other wise weak amalgam will result other wise weak amalgam will result..

55-- A proper sized and designed condenser must be A proper sized and designed condenser must be used used::

i.i. It should be small enough to exert great pressure, It should be small enough to exert great pressure, but not too small to cause holes in the amalgam but not too small to cause holes in the amalgam..

iiii. . It should be properly angulated to reach all areas of It should be properly angulated to reach all areas of the cavity the cavity..

iii.iii. The face of the condensed must be either flat, The face of the condensed must be either flat, smooth or serrated smooth or serrated..

66- - Condensation should be completed under clean Condensation should be completed under clean dry condition dry condition..

* * Condensation techniqueCondensation technique::

11- - By hand condensation and it should be as followsBy hand condensation and it should be as follows..

a.a. The restoration is built from small successive increment The restoration is built from small successive increment. .

b.b. In case of compound cavities, the box should be filled first In case of compound cavities, the box should be filled first to the level of pulpal floor, then the occlusal to the level of pulpal floor, then the occlusal..

c.c. Small piece of amalgam is carried by amalgam carrier and Small piece of amalgam is carried by amalgam carrier and forced into the cavity forced into the cavity..

d.d. The first layer is condensed with great force using small The first layer is condensed with great force using small condenser from the center of the cavity to cavity condenser from the center of the cavity to cavity

margins margins. .

e-e- The mercury rich amalgam on the surface is The mercury rich amalgam on the surface is removed with spoon excavator removed with spoon excavator. .

f-f- The process is repeated until the cavity is The process is repeated until the cavity is completely filled completely filled..g- g- A final dry piece is condensed to over fill the A final dry piece is condensed to over fill the cavity and over come the excess mercury of cavity and over come the excess mercury of the last layer and then this layer is removed the last layer and then this layer is removed leaving the surface of amalgam with no leaving the surface of amalgam with no excess mercuryexcess mercury..

22- - Mechanical condensation: by Mechanical condensation: by ultrasonic deviceultrasonic device

* * Advantages of mechanical condensationAdvantages of mechanical condensation:: 11- - It is more standardizedIt is more standardized . .

22- - Less fatigue to the operatorLess fatigue to the operator..

33- - It produces homogenous amalgamIt produces homogenous amalgam..

44- - More strength property for the final amalgamMore strength property for the final amalgam..

55- - Less flowLess flow..

66- - More stabilityMore stability..

77- - Less expansionLess expansion..

Carving of AmalgamCarving of Amalgam::

11- - We use suitable amalgam carverWe use suitable amalgam carver..

22- - Amalgam must not be carved unless it Amalgam must not be carved unless it becomes hard enough to resist carving becomes hard enough to resist carving

instrument ( for about 3.5 min instrument ( for about 3.5 min(. (.

33- - Sharp instrument must be used for carving, Sharp instrument must be used for carving, to not disturb the matrix to not disturb the matrix. .

44- - Avoid carving towards cavity margins to Avoid carving towards cavity margins to avoid under filling and expression of avoid under filling and expression of excess mercury towards the margin excess mercury towards the margin..

Excess Hg at the margins may causeExcess Hg at the margins may cause::

a- Marginal disintegrationa- Marginal disintegration . .

b- Marginal leakageb- Marginal leakage..

c- Tarnish and corrosionc- Tarnish and corrosion..

55- - In compound cavities, the occlusal portion In compound cavities, the occlusal portion is carved 1 is carved 1 stst before removal of matrix before removal of matrix..

66- - After carving of the occlusal portion , the After carving of the occlusal portion , the matrix holder is unscrewed and band is matrix holder is unscrewed and band is removed either buccally or lingually. removed either buccally or lingually. Avoid its removal occlusally to avoid Avoid its removal occlusally to avoid fracture of the margins fracture of the margins..

77- - The proximal contour is carved and then The proximal contour is carved and then contact is checked by using dental floss contact is checked by using dental floss

silk silk. .

Double burnishing techniqueDouble burnishing techniqueMeans the amalgam is pre and post carving Means the amalgam is pre and post carving burnishedburnished

Pre carving burnishingPre carving burnishingUsing large sized burnisher with heavy Using large sized burnisher with heavy pressurepressure

Benefits of precarving Benefits of precarving burnishingburnishingA-Increase adaptation of amalgam to cavity A-Increase adaptation of amalgam to cavity walls and margins walls and margins

B-Bring the mercury to the surfaceB-Bring the mercury to the surface

C- More cohesive amalgamC- More cohesive amalgam

D-Continue the process of condensationD-Continue the process of condensation

Post carving burnishingPost carving burnishingSmall sized burnisher with gentle strokes Small sized burnisher with gentle strokes just to smoothen the amalgamjust to smoothen the amalgam

Finishing and polishing of AmalgamFinishing and polishing of Amalgam::

It should be done to give a luster-like smooth surface It should be done to give a luster-like smooth surface after at least 24 hrs after at least 24 hrs..

* * Finishing and polishing is achieved by usingFinishing and polishing is achieved by using::

11- - Rotating finishing instruments which includeRotating finishing instruments which include::

a- Finishing stones as carburundum green stones in a- Finishing stones as carburundum green stones in form of : coarseform of : coarse..

mediummedium

finefine

they are used to correct surface discrepanciesthey are used to correct surface discrepancies..

b- b- InterproximalInterproximal finishing instruments finishing instruments asas::

i- i- finishing strips in form of : coarsefinishing strips in form of : coarse..

mediummedium

finefine

ii- Abrasive discsii- Abrasive discs..

they are used to correct over hangs and give they are used to correct over hangs and give smooth interproximalsmooth interproximal surfacesurface..

c- Finishing burs12 flutedc- Finishing burs12 fluted..

22- - Rotating polishingRotating polishing instruments instruments includeinclude::

a- Rubber cups in form of coarse, medium or a- Rubber cups in form of coarse, medium or fine applied with polishing paste at low speedfine applied with polishing paste at low speed..

b- Rotating soft brush applied with polishing b- Rotating soft brush applied with polishing pastepaste . .

* * If amalgam restoration is not finished If amalgam restoration is not finished and polished, then the surface remains and polished, then the surface remains rough leads torough leads to::

a- a- Surface porositiesSurface porosities..

b- Food and plaque accumulationb- Food and plaque accumulation..

c- Tarnish and corrosionc- Tarnish and corrosion..

d- Concentration of stressesd- Concentration of stresses..

ADVANTAGESADVANTAGES::

11- - High compressive strength properties High compressive strength properties (45000PSI (45000PSI(.(.

22- - Low coefficient of thermal expansionLow coefficient of thermal expansion..

33- - Indestructibility in oral fluidIndestructibility in oral fluid..

44- - Easy of manipulationEasy of manipulation..

55- - It is capable to take and maintain a good It is capable to take and maintain a good polish polish..

DISADVANTAGESDISADVANTAGES::

11- - Low tensile strengthLow tensile strength..

22- - Bad esthetics due to unnatural color and the Bad esthetics due to unnatural color and the tendency for corrosion tendency for corrosion..

33- - High thermal conductivityHigh thermal conductivity..

44- - Slight changes in dimension during settingSlight changes in dimension during setting..

THANK THANK YOUYOU