Amalgam (dentistry) packs the plastic mass, before it sets, into the cavity. The amalgam expands ≈0.1% over 6–8 hours on setting. The final structure is a metal matrix composite, where γ, η and γ phases, are a matrix for unreacted original alloy, minus the fast-reacting β-phase and excess Sn. Amalgam is a mixture of two or more metals (alloy) with mercury which has been purified first by distillation to remove impurities. Currently, major components of the alloy are silver tin and copper. The composition of the alloy powder is controlled by ISO standard for dental amalgam alloy (ISO 1559) to control the
Amalgam (dentistry) properties of amalgam. Creep or plastic deformation happens when subjected to intra-oral stresses such as chewing or grinding. Creep causes the amalgam to flow and protrudes from the margin of the cavity forming unsupported edges. ‘Ditch’ is formed around the margins of the amalgam restoration and make it prone to fracture. The γ2 phase of amalgam is primarily responsible for high values of creep. Corrosion occurs when an electrolytic cells of anode and cathode set up in the presence of electrolytes. The multiphase structure of dental amalgam can contribute as an anode or cathode with saliva as electrolytes. Corrosion may