Failure Risk of Composite Resin and Amalgam Restorations: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis were conducted to compare the failure risk between amalgam and composite resin materials in permanent posterior teeth.

Study eligibility requirements included clinical trials and observational studies with at least 12 months of follow-up. English-language studies from 1990 onwards were the only studies included. This review follows the Cochrane Handbook for Systematic Reviews of Interventions and the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Our search strategy included using the following databases: PubMed, Cochrane, and Google Scholar. The primary outcome was restoration failures, defined as restoration replacements, tooth and restoration fractures, secondary caries, postoperative sensitivity, and toothaches. We conducted a random-effects meta-analysis to determine the risk ratio (RR) of the included studies, and publication bias was assessed. The Cochrane Risk of Bias tool was employed to evaluate the quality of the clinical trials, while the Newcastle-Ottawa scale was used to assess the quality of other studies.

The results were derived from 13 studies. The failure proportion for amalgam ranged from 0% to 50.0%, while that of composite resin restorations ranged from 0% to 62.7%. The meta-analysis did not find any statistically significant difference in failure risk between amalgam and composite resin restorations (RR: 0.96, 95% confidence intervals: 0.68-1.34). The Egger's test results did not show any significant evidence of publication bias in the meta-analysis (P > .05).

This review did not reveal any statistically significant difference in the RR between composite resin and amalgam restorations. However, in their analyses, the 13 studies used varying definitions of failure and did not account for some important factors that might have influenced restoration failures. Future reviews need to account for other influential variables that contributed to restoration failures.