Longevity of low- and high-copper amalgams analyzed by preparation class, tooth site, patient age, and operator

The purpose of this study was to compare the long-term survivals of two low-copper and three high-copper amalgam alloys, and to analyze four clinical factors for their possible effects on the restoration survivals. Some 1476 polished restorations were placed in hospital patients by a large number of operators and assessed over periods of up to 10 years. There were no significant survival differences found among the high-copper alloys and one low-copper alloy, and their survivals were significantly better than for the other low-copper alloy. These results could not have been reliably predicted from the different compositions and creep values of the alloys. A significant effect on restoration survivals was also found with different operators.