title: Cross-sectional radiographic survey of amalgam and resin-based composite posterior restorations.
abstract: OBJECTIVE
  To compare the failure rate of posterior interproximal amalgam restorations to resin-based composite restorations in a random young adult population.
  
  
  METHODS
  Bilateral bitewing radiographs of 459 young adults were screened. A total of 14,140 interproximal surfaces were examined, recorded, and statistically analyzed. Rate of failure was determined by the number of restorations with radiographic evidence of secondary caries and/or overhanging margins.
  
  
  RESULTS
  Of the 650 restored interproximal surfaces (5% of all clearly demarcated interproximal surfaces), 86 (13%) demonstrated distinct interproximal secondary caries and 22 (3%) had overhanging margins. Of the 557 amalgam and 93 resin-based composite interproximal restorations, secondary caries were shown in 46 (8%) and 40 (43%), respectively, and overhanging margins in 21 (4%) and only 1 (1%), respectively. Generally, when secondary caries and overhanging margins were considered, the failure rate of amalgam and resin-based composite interproximal restorations was 12% and 44%, respectively.
  
  
  CONCLUSIONS
  Higher failure rates were observed in resin-based composite restorations than in amalgam restorations. Secondary caries was the main reason for failure. Overhanging margins were not a primary factor in restoration failure. The vast use of posterior interproximal resin-based composite restorations should be reconsidered, and their limited long-term performance should be kept in mind.
authors.affiliation: Department of Oral Rehabilitation, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel-Aviv University, Tel-Aviv, Israel. liranl@post.tau.ac.il <liranl@post.tau.ac.il>
authors.forename: Liran
authors.initials: L
authors.lastname: Levin
authors.forename: Marius
authors.initials: M
authors.lastname: Coval
authors.forename: Selly B
authors.initials: SB
authors.lastname: Geiger
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000293:Adolescent; D000328:Adult; D003188:Composite Resins / Q000737:chemistry*; D003430:Cross-Sectional Studies; D003723:Dental Amalgam / Q000737:chemistry*; D003731:Dental Caries / Q000000981:diagnostic imaging; D018772:Dental Marginal Adaptation; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent; D006801:Humans; D016015:Logistic Models; D016017:Odds Ratio; D011140:Polyurethanes / Q000737:chemistry*; D011859:Radiography
chemical_list: D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D011140:Polyurethanes; D003723:Dental Amalgam