Creep versus marginal fracture of amalgam restorations.

In the literature there is controversy over the existence of a correlation between creep and marginal deterioration of amalgam restorations. It was the aim of this study to re-investigate this correlation. In five clinical trials, 2068 amalgam restorations were made of six conventional alloys and ten high copper systems. The results show a correlation between creep and marginal fracture in the conventional, low copper amalgams. No correlation could be found for the group of high copper, non-gamma-2, amalgams. It is emphasized that dental practitioners should not buy their amalgam alloy on the basis of creep data, because wrong decisions might be taken. Evidence from a controlled clinical study is a more reliable criterion.