Clinical behaviour of high-copper amalgams with time, site, size and class of cavity preparation.

In this study 767 amalgam restorations placed in the posterior permanent teeth of 122 patients were evaluated at 6-monthly intervals up to 2 years. Six commercially available high-copper alloy amalgams were assessed for surface roughness, surface tarnish, marginal staining and marginal fracture and the results were related to product, restoration age, restoration cavity class type, restoration size (normal or large Class II preparations) and tooth type (premolar or permanent molar). Dispersalloy (Johnson and Johnson, East Windsor, USA) gave restorations which were overall superior for the clinical characteristics examined. Large restorations on the occlusal surfaces of molar teeth showed more signs of deterioration over the study than did other restoration types. However, all restorations remained clinically satisfactory throughout the study.