title: Amalgam or composite fillings--which material lasts longer?
abstract: METHODS
  Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase and LILACS. Hand searched relevant journals and attempted contact with authors of unpublished studies and manufacturers.
  
  
  METHODS
  Randomised controlled trials comparing dental resin composites with dental amalgams in permanent posterior teeth with a minimum follow up of three years were eligible.
  
  
  METHODS
  Data were extracted independently by a minimum of two review authors using specially designed data extraction forms. Risk of bias was assessed using the Cochrane risk of bias tool. Relative risks and 95% CIs were extracted for dichotomous data and mean difference (MD) or standardised mean difference (SMD) for continuous data. Relative risk was combined in a meta-analysis.
  
  
  RESULTS
  Seven studies were included. Two were parallel and five split-mouth design. Data from 871 participants were available from the two parallel studies but several of the split-mouth studies did not report the number of participants. All studies were considered at high risk of bias. Only data from the two parallel studies were included in the primary meta-analysis. Failure rates in these studies were recorded for between five and seven years. The risk ratio of failure for composite versus amalgam was 1.89 with 95% CI of 1.52-2.35. The increased failure was primarily due to caries rather than fracture.
  
  
  CONCLUSIONS
  There is low-quality evidence to suggest that resin composites lead to higher failure rates and risk of secondary caries than amalgam restorations.
authors: Department of Adult Oral Health, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, and Department of Primary Care Health Sciences, University of Oxford, Oxford, UK.
authors: Dominic
authors: D
authors: Hurst
mesh_terms: D000180:Acrylic Resins / Q000627:therapeutic use*; D003188:Composite Resins / Q000627:therapeutic use*; D003723:Dental Amalgam / Q000627:therapeutic use*; D003731:Dental Caries / Q000628:therapy*; D003793:Dental Restoration, Permanent / Q000379:methods*; D019229:Dentition, Permanent; D006801:Humans; D011140:Polyurethanes / Q000627:therapeutic use*
chemical_list: D000180:Acrylic Resins; D003188:Composite Resins; D011140:Polyurethanes; D003723:Dental Amalgam