Amalgam

From WikiDent

Contents 1 Benefits 2 Definitions 3 Composition 4 Commercial Dental Alloys

Benefits

Inexpensive Simple technique Over a century of historical record Fewer allergies than resin composite

Definitions

Lathe Cut

• lathe cut alloys require more mercury (45-50%)

Sperical

• spherical alloys require less mercury (40-45%)

Admixed High Copper

Composition

• Silver (Ag)
  • increases strength
  • increases expansion

• Mercury (Hg)
  • activates reaction
  • only pure metal that is liquid �at room temperature
• Copper (Cu)
  • ties up tin
    • reducing gamma-2 formation
  • increases strength
  • reduces tarnish and corrosion
  • reduces creep
    • reduces marginal deterioration

• Tin (Sn)
  • decreases expansion
  • decreased strength
  • increases setting time
• Minor Metals
  • Indium (In)
    • decreases surface tension
    • reduces amount of mercury necessary
    • reduces emitted mercury vapor
    • reduces creep and marginal breakdown
    • increases strength
  • Palladium (Pd)
    • reduced corrosion
    • greater luster
  • Zinc (Zn)
    • less marginal breakdown
    • causes delayed expansion with low Cu alloys if contaminated with moisture during condensation

Amalgam is composied of a silver-mercury matrix containing filler particles of silver-tin Filler

• Gamma (bricks) - Ag₃Sn called gamma

Matrix

• Gamma 1 (cement) - Ag₂Hg₃
• Gamma 2 (voids) - Sn₈Hg

Commercial Dental Alloys

• Dispersalloy (1960)
  • Admixed high copper alloy
• Tytin (1970)
  • Spherical
• Valiant PhD
  • Contains Palladium for high polish