Introduction
Amalgam is a material used for dental restorations for more than 170 years. The name is refered to a chemicalphysical process, through which is done a mixing of metals in different physical states and the product then passes to a crystalline phase. Usually in our daily work, we hear about Silver alloy amalgam, thinking it is referred to the metal in the major amount in the powder, but in fact, the metal in the major amount in full mixture is Hg. For the first time Amalgam alloy was used from peoples in Latin America. In 1816, it was used from August Traveau, while England it was used first from Bell. Black, in 1896 used the first recipe for dental amalgam alloy. There are included these elements: Hg (mercury) – 52% of all the mixture. The rest was compound from: Ag (silver) – 68.5% Sn (tin) – 25.5% Cu (copper) – 5% Zn (zinc) – 1% Essentially, the amalgam alloy preparation predicts a mixture of a liquid substance with a solid one, the latter is compound from little particles of many elements. The percentage of these elements changes according to the type of the alloy used. And according to these percentages, are done many classifications : the classic amalgam alloy, amalgam without gamma-2 phase, amalgam with high copper, etc. the higher percentage of copper, provides to the alloy a higher mechanical properties and resistance to corrosion.