Marginal failure of amalgam. Effect of alloy selection and bite forces.

Four amalgam alloys were used in a two and a half year study. 163 class II restorations were made and the marginal breakdown was studied. The biting forces of the patients were estimated and divided in three groups. The result indicated that the conventional amalgam showed more breakdowns than the high copper amalgams. Among these a dispersed and a ternary amalgam had least marginal failures. The amount of defects tended to be correlated to the biting force for the conventional and the dispersed amalgam.