II-IMKG_Kuliah 1amalgam 0809_7 Juni 2011

7/30/2019 II-IMKG_Kuliah 1amalgam 0809_7 Juni 2011

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Dental Amalgam

Pustaka :

Anusavice : Phillps Science of Dental materials

Combe E.C. : Notes on Dental Materials

Endanus Harijanto


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Definitions (1)

Amalgam = an alloy of mercury and one

or more other metals

Dental amalgam is produced by mixingliquid mercury with solid particles of an

alloy of silver, tin, copper, and

sometimes zinc, palladium, indium andselenium.


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Definitions (2)

Trituration

Amalgam alloy is mixed with mercury.

Amalgamation Process

Mercury dissolves the surface of alloy particles

a composite plastic mass (some new phasesform).

Setting and hardening occur as the liquid

mercury is consumed in the formation of new

solid phases.


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Bahan / Isi Amalgam

Bahan Dasar Silver

Tin

Copper

Mercury

Bahan lain Zinc

Indium

Palladium

Endanus Harijanto


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Bahan Dasar (1)

Silver (Ag)

increases strength

increases expansion

Tin (Sn)

decreases expansion

decreased strength

increases setting time


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Bahan Dasar (2) Copper (Cu)

ties up tin

reducing gamma-2 formation

increases strength

reduces tarnish and corrosion

reduces creep


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Bahan Dasar (3)

Mercury (Hg) activates reaction

only pure metal that is liquidat room temperature


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Bahan Dasar (4)

Cairan logam merkuri berwarna putih keperak-perakan

Bentuk logam valensi 0

Formula umum senyawa valensi 2 HgX2 Senyawa merkuro Hg2X2


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Bahan Dasar (5)

Merkuri berbahaya terhadap kesehatan ok: Senyawa merkuri dapat membentuk ikatan dengan ligan

organik

Ikatan kuat jika ligannya kelompok Metil (CH3)

Ikatan tidak begitu stabil jika ligannya kelompok Etil

(CH2CH3) Ikatan tidak stabil jika radikalnya berisi > 2 atom C mis:

fenilmerkuri khlorida (C6H5-Hg-Cl)


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Bahan Lain (6)

Zinc (Zn) used in manufacturing

decreases oxidation of other elements

provides better clinical performance less marginal breakdown

Osborne JW Am J Dent 1992

causes delayed expansion with low Cu alloys if contaminated with moisture during condensation

Phillips RW JADA 1954

H2O + Zn ZnO + H2


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Bahan Lain

Indium (In)

decreases surface tension

reduces amount of mercury necessary reduces emitted mercury vapor

reduces creep and marginal breakdown

increases strength

must be used in admixed alloys


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Bahan Lain

Palladium (Pd)

reduced corrosion

greater luster


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KOMPOSISI AMALGAM

Endanus Harijanto


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Amalgam Alloy Composition

ANSI/ADA Spec. #1 (ISO 1559)

requires that amalgam alloys be

predominantly silver (Ag) and tin (Sn). containing Zn > 0.01%Zinc Containing containing Zn < 0.01%nonzinc


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Classification

Low-copper (Conventional) amalgam alloy(at least 65 wt% Ag, 29 wt% Sn, < 6 wt% Cu)

lathe-cut (irregular) powder or spherical particles or mixed

Ag-Sn High-copper amalgam alloy

(6-60 wt% Cu)

(1) Admixed (Ag-Sn + Ag-Cu)

A mixture of irregular and spherical particles of different or

same composition (2) Unicomposition or Single composition (Ag-Sn-Cu)

All spherical particles


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Classification

Admixed amalgams containing 10%

to 15% indium (In) in the mercury

Newly developed

Decreases the amount of Hg needed

decreases the Hg vapor during and aftersetting

Low creep and lower early-compressive

strengths, but higher final strengths


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Lathe-cut v.s. Spherical

Irregular or Lathe-cut Spherical


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spherical alloysrequire less mercury

smaller surface area easier to wet40 to 45% Hg

admixed alloysrequire more mercury

lathe-cut particles more difficult to wet

45 to 50% Hg

Lathe-cut v.s. Spherical

II-IMKG_Kuliah 1amalgam 0809_7 Juni 2011

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