Effect of age on the creep of a high-copper amalgam.

A previous study of the effect of final Hg content on the static creep of a single-composition high-Cu amalgam alloy showed a sudden increase or jump in creep at a specific Hg content, and the presence of the Sn-Hg phase (gamma 2) at final Hg contents subsequent to this creep jump. This observation is consistent with the less-than-optimum clinical performance reported for this alloy. A repetition of these tests conducted on test specimens 3 months and 6 months of age showed the creep jump to shift to higher Hg contents. However, even at 6 months of age, the final Hg content to be expected in clinical restorations was still positioned after the initiation of the creep jump where a small amount of gamma 2 is known to be present.