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 removing toxic substances from the body, when such treatment is performed solely at the recommendation or suggestion of the dentist, is improper and unethical". Under the comments of the American Dental Association before the FDA's Dental Products Panel of the Medical Devices Advisory Committee, the ADA supports the 2009 FDA ruling on dental amalgam. ADA states that "dental amalgam has an established record of safety and effectiveness, which the scientific community has extensively reviewed and affirmed." The ADA also supports the 2017 EPA wastewater regulation and is providing information and assistance to its members in implementation of amalgam separators. The