Change in Compressive Strength of Amalgams by Corrosion

Conventional lathe cut amalgams showed a significant decrease in compressive strength when stored in 0.5 per cent saline solution for one week. The compressive strength increased by three-month storage in distilled water or in saline solution for all of the amalgams tested. Then the significant decrease was found in the strength of all of the conventional lathe cut amalgams and some of the conventional spherical and high-copper type ones during the three-month period from the fourth to sixth month in water and saline solution. High-copper type amalgams seemed to be the most resistant to corrosive attack in respect to the compressive strength. Exceptionally a ternary system of high-copper amalgam containing In exhibited a marked reduction in strength by placing it in the saline solution for six months. Zn free alloys were slightly insensitive to the attack of the saline solution as compared with Zn containing alloys of the same brand.