Failure at the Margin of Amalgams as Affected by Cavity Width, Tooth Position, and Alloy Selection

The effects of alloy, cavity width, and tooth position on failure rate at the margins of 429 two-year-old Class II amalgams were analyzed. Interpretation of the results from a factorial design indicated that: (1) There were significant differences among alloys; (2) conservative preparations exhibit less breakdown than wider preparations; and (3) there was less failure in lower premolars than in other posterior teeth.