1. KOMPOSISI AMALGAM Endanus Harijanto

2. 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”

3. 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

4. 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 after setting • Low creep and lower early-compressive strengths, but higher final strengths

5. Composition

6. Lathe-cut v.s. Spherical Irregular or Lathe-cut Spherical

7. Symbols of Phases

8. Silver-Tin (Ag-Sn) System (1) • Most commercial alloys fall within the limited composition range of B to C. • (b + g) and g • If Sn > 26.8 wt%  g + Sn-rich phase is formed.  Sn-Hg phase (g2) in the final product which lacks corrosion resistance and is the weakest component.

9. Silver-Tin (Ag-Sn) System (2) • 4 wt% to 5 wt% Cu is substituted for Ag. • Hardens and strengthens the Ag-Sn alloy • Zinc = Deoxidizer: a scavenger (O2) during melting  formation of oxides • Can cause an abnormal expansion if the amalgam is condensed in the presence of moisture.

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