Three-year clinical comparison of three amalgam alloy types emphasizing an appraisal of the evaluation methods used

Five different evaluation techniques were used to measure the marginal breakdown of three-year-old amalgam restorations. The most useful method appeared to be one in which photographs of all restorations were ranked in descending order starting with the restoration that had the least marginal breakdown and ending with the restoration that had the greatest deterioration. Three different alloys were evaluated and the results confirm those of previous studies; the alloy having the lowest creep was superior whereas restorations placed with the alloy having the highest creep displayed the greatest marginal breakdown.