Longevity of Amalgam Versus Composite Resin Restorations in Permanent Posterior Teeth: A Systematic Review

The present systematic review aims to compare the longevity of amalgam and composite resin restorations in adult human posterior permanent teeth, evaluating clinical performance, survival rates, failure causes, and influencing factors. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a comprehensive search was conducted in PubMed, Scopus, Web of Science, and other databases. Studies were included if they assessed the longevity of amalgam and composite resin restorations in adult posterior teeth with at least one year of follow-up. The Newcastle-Ottawa Scale (NOS) and Cochrane Risk of Bias (ROB) tool were used for the assessment of risk of bias. Eight studies (2003-2023) met the inclusion criteria, comprising randomized clinical trials, prospective, retrospective, and cross-sectional studies. Amalgam restorations exhibited superior longevity, with median survival times exceeding 16 years, compared to 11 years for composite restorations. Secondary caries was the most common cause of composite failure, whereas fracture was the primary reason for amalgam replacement. Patient factors, including oral hygiene and bruxism, significantly influenced restoration longevity. Amalgam restorations demonstrate greater durability than composite resins in posterior teeth. However, aesthetic preferences and advancements in composite materials continue to drive their usage. Future research should focus on improving composite longevity to provide viable alternatives to amalgam.