Dr R V SUBRAMANYAM’S DENTAL MATERIALS LECTURE NOTES
Classification of Amalgam Alloys
Amalgam: Alloy of mercury with one or more metals.
Amalgam alloy: Alloy which combines with mercury to form amalgam.
Dental amalgam alloy: Alloy that is combined with mercury to form amalgam used for dental
Amalgamation: Setting reaction of amalgam alloy with mercury.
Trituration: The act of mixing amalgam alloy with mercury.
Condensation: The process of placing the plastic amalgam mass into the tooth cavity and
applying forces on it to adapt amalgam to the cavity walls.
Burnishing: The act of smoothening the surface and margins of amalgam after condensation.
Amalgam was first used by the Chinese. There is a mention of
Silver-Mercury paste by Su Kung (A.D. 659) in the Chinese
1578: Li Shihchen used 100 parts of Hg, 45 parts of Ag and 900
parts of Sn.
1826: Introduction of Silver-Mercury paste (pate-d'argent) by
Peter O. Taveau of Paris, France.
1833: Introduction of Silver-Mercury paste in the USA by
1870: Elisha Townsend & J.F.Flagg improvised amalgam alloy
1895: G.V.Black improvised composition of dental amalgam alloy
which was in use for many years. (Ag 67%; Sn 27%; Cu 5%; Zn
1900: Introduction of Copper amalgam.
1963: Introduction of Admixed amalgam alloy by Innes and Youdelis
A. According to content
Silver Amalgam: Silver more than 65%.
Copper Amalgam: 70% Hg and 30% Cu.
Preamalgamated alloys: Contain less than 3% of Hg.
Noble metal amalgam alloys: Contain Au and/or Pd.
B. According to presence or absence of Zinc
Zinc-containing alloys: More than 0.01% Zn.
Zinc-free alloys: Less than 0.01% Zn.
C. According to Copper content
Low Copper alloys (2-4% Cu)
High copper alloys (13-30% Cu) Admixed alloy ( 1/3rd
Low Cu + 2/3rd Ag-Cu eutectic)
Unicompositional or Single compositional alloy
D. According to number of metals in the alloy
Binary alloy: Ag; Sn
Silver coins which were powdered and