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) by using database in the Cochrane Library where randomized controlled trials of few studies comparing dental resin composite with dental amalgams in permanent posterior teeth were compared. This review supports the fact that amalgam restorations are particularly useful and successful in parts of the world where amalgam is still the material of choice to restore posterior teeth with proximal caries. Though, there is insufficient evidence to support or refute any adverse effects amalgam may have on patients, new research is unlikely to change opinion on its safety and due to the decision for a global phase-down of amalgam (Minamata Convention