Background: The authors conducted a prospective cohort clinical study to investigate the effectiveness of alternative treatments to the replacement of defective amalgam restorations.
Methods: Fifty patients aged 21 through 77 years (mean age, 56 years) with 113 defective amalgam restorations that were diagnosed during treatment planning participated in the study. The authors assigned each tooth to one of five treatment groups: repair with amalgam (n = 20), sealing of defective margins (n = 23), refinishing (n = 23), replacement (n = 22) or no treatment (n = 25). The replacement and no-treatment groups served as comparison groups, and the authors assigned 47 teeth randomly to these groups. Two clinicians examined the restorations before and after the assigned treatment and at subsequent recall visits by using modified U.S. Public Health Service criteria including marginal adaptation, anatomic form, occlusal and proximal contact, postoperative sensitivity and secondary caries.
Results: The clinicians examined 94 restorations (83 percent) at the one-year recall visit, 74 (65 percent) at the two-year recall visit and 54 (48 percent) at the seven-year recall visit. They observed most of the downgraded and failed restorations after the first two years of clinical service.
Conclusions: The study results show that some degree of degradation occurred in all treatment groups, including the replacement group, at the seven-year recall examination, with no significant failure rate. The results support the repair of defective amalgam restorations as an alternative to replacement. Furthermore, the study findings show that in future controlled clinical trials, all teeth may receive random assignment.
Clinical implications: The study findings support repair rather than replacement of amalgam restorations with localized defects. Randomized controlled trials are needed to confirm these findings.