The effect of setting time on the clinical performance of a high-copper amalgam alloy.

The purpose of this clinical study was to evaluate the factor of the setting rate/Eames working time on fracture at the margins of amalgams. One batch of a high-copper amalgam was modified to obtain two setting rates, one fast and one slow setting. Two dentists originally placed 134 amalgam restorations in 23 patients. Both dentists used a rubber dam throughout the restorative procedure and prepared cavities as conservatively as possible. The amalgams were condensed by hand and carved with sharp instruments. At 1 year 124 restorations and at 2 years 115 restorations were evaluated for fracture at the margins. Results indicated that there was no significant clinical difference between a slow- and fast-setting alloy, nor was there a difference between the operators.