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
Dental amalgam controversy years. All available world-wide research indicates that amalgam is not harmful to health... No Government or reputable scientific, medical or dental body anywhere in the world accepts, on any published evidence, that dental amalgam is a hazard to health." The Irish Dental Association provides additional detail in a published patient information letter. France has publicly recognized the safety and effectiveness of amalgam restorations. A position paper on the Association Dentaire Française website states that amalgam restorations have proven to have no biological or toxic effect. They also mention that no serious pathological fact has ever been observed and no general