title: A retrospective clinical study on longevity of posterior composite and amalgam restorations.
abstract: OBJECTIVE
  The purpose of this study was to evaluate retrospectively the longevity of class I and II amalgam and composite resin restorations placed in a general practice.
  
  
  METHODS
  Patient records of a general practice were used for collecting the data for this study. From the files longevity and reasons for failure of 2867 class I and II amalgam and composite resin restorations placed in 621 patients by two operators between 1990 and 1997 were recorded in 2002.
  
  
  RESULTS
  912 amalgam restorations (502 by operator 1 and 410 by operator 2) and 1955 posterior composite resin restorations (1470 by operator 1 and 485 by operator 2) were placed. One hundred and eighty-two amalgam and 259 posterior composite resin restorations failed during the observation period. The main reasons for failure of the restorations were caries (34%), endodontic treatment (12%) and fracture of the tooth (13%). Life tables calculated from the data reveal a survival for composite resin of 91.7% at 5 years and 82.2% at 10 years. For amalgam the survival is 89.6% at 5 years and 79.2% at 10 years. Cox-regression analysis resulted in a significant effect of the amount of restored surfaces on the survival of the restorations. No significant effect of operator, material as well as combination of material and operator was found.
  
  
  CONCLUSIONS
  In the investigated general practice, two dentists obtained comparable longevity for amalgam and composite resin restorations.
authors.affiliation: Department of Cariology and Endodontology, Radboud University Medical Centre Nijmegen, PO Box 9101, NL 6500 HB Nymegen, The Netherlands. n.opdam@dent.umcn.nl
authors.forename: Niek J M
authors.initials: NJ
authors.lastname: Opdam
authors.forename: Ewald M
authors.initials: EM
authors.lastname: Bronkhorst
authors.forename: Joost M
authors.initials: JM
authors.lastname: Roeters
authors.forename: Bas A C
authors.initials: BA
authors.lastname: Loomans
mesh_terms: D000134:Acid Etching, Dental; D003188:Composite Resins / Q000737:chemistry*; D003723:Dental Amalgam / Q000737:chemistry*; D003731:Dental Caries / Q000150:complications; D003736:Dental Cavity Lining; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000145:classification / Q000592:standards / Q000706:statistics & numerical data; D005260:Female; D005500:Follow-Up Studies; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D015993:Life Tables; D008297:Male; D008689:Methacrylates / Q000737:chemistry; D010756:Phosphoric Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D012189:Retrospective Studies; D012390:Root Canal Therapy; D016019:Survival Analysis; D014082:Tooth Fractures / Q000150:complications
chemical_list: C084544:Clearfil Linerbond System; D003188:Composite Resins; D005899:Glass Ionomer Cements; D008689:Methacrylates; D010756:Phosphoric Acids; D019279:Resin Cements; D003723:Dental Amalgam; C030242:phosphoric acid