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. Phases in Amalgam Alloys and Set Dental Amalgams
Symbols of Phases
Phases in Amalgam Alloys and Set Dental Amalgams
Formula g
Ag3Sn g1
Ag2Hg3 g2
Sn7-8Hg b
Ag4Sn (silver-rich) e
Cu3Sn h
Cu6Sn5
Silver-copper eutectic
Ag-Cu

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.

10. Ada Pertanyaan ?