title: An overview of reasons for the placement and replacement of restorations.
abstract: OBJECTIVE
  Surveys on reasons for the placement and replacement of restorations have been conducted in various countries. The purpose of this paper is to bring together and review the data of 10 such surveys with similar methodology.
  
  
  METHODS
  The studies reviewed are all based on the protocol described by Mjör in 1981.
  
  
  RESULTS
  The surveys reviewed provide data on the reasons for the placement and replacement of a total of 32,777 restorations. Notwithstanding differences between countries, different groups of practitioners and minor variations in methodology, the data included in the selected surveys indicate that everyday clinical practice in Scandinavia, UK and USA during the 1980s and 1990s has involved more replacement than initial restorations, with the ratio of initial to replacement restorations ranging from 1:1.1 to 1:2.4 for amalgam and 1:1.1 to 1:3.8 for composite materials. Primary caries has been consistently found to be the principal reason for the provision of initial restorations of amalgam and composite. The principal reason for the replacement of restorations of amalgam and composite has remained secondary caries as diagnosed clinically. Material failures (marginal degradation, discoloration, bulk fracture and loss of anatomic form) accounted for the replacement of more restorations of composite than amalgam. Recent surveys have reported secondary caries as the principal cause of failure of restorations of glass-ionomer cements and related materials.
  
  
  CONCLUSIONS
  The clinical diagnoses of caries may continue to be found to account for the placement and replacement of most intracoronal restorations. Surveys of the type reviewed provide valuable insight into patterns of provision of dental care and highlight research priorities in relation to direct restorations.
authors.affiliation: Department of Restorative Dentistry, University of Manchester, USA.
authors.forename: V
authors.initials: V
authors.lastname: Deligeorgi
authors.forename: I A
authors.initials: IA
authors.lastname: Mjör
authors.forename: N H
authors.initials: NH
authors.lastname: Wilson
mesh_terms: D003188:Composite Resins; D003625:Data Collection; D003723:Dental Amalgam; D003731:Dental Caries / Q000628:therapy; D003793:Dental Restoration, Permanent / Q000706:statistics & numerical data*; D006801:Humans; D019239:Practice Patterns, Dentists'; D019233:Retreatment; D006113:United Kingdom
chemical_list: D003188:Composite Resins; D003723:Dental Amalgam