Early strength and adaptability of amalgam in relation to coherence time.

The minimum mixing time required to give a coherent mix of a dental amalgam ("coherence time") was determined for eleven representative materials using two different amalgamators. The effect of mixing these amalgams at various multiples of their coherence time on early compressive strength and adaptability was determined. It was found that the two amalgamators gave different coherence time values for the alloys, but that the strength data for any given alloy was similar for a given multiple of coherence time. Longer mixing tended to yield amalgams of greater early strength, but reduced the adaptability of the mixed material.