title: Meta analysis of the treatment-related factors of external apical root resorption.
abstract: OBJECTIVE
  To elucidate possible treatment-related etiological factors--such as, duration of treatment and apical displacement--for external root resorption.
  
  
  METHODS
  Meta-analysis of the available English-language literature.
  
  
  METHODS
  Papers with a sample size > 10, fixed appliances, pre- and post-operative radiographs, and apical displacement recorded were included. History of trauma, prior root resorption and endodontic treatment were excluded. Appropriateness of these selections was tested with a 'funnel plot' analysis.
  
  
  METHODS
  Correlations between root resorption, apical displacement, and treatment duration.
  
  
  RESULTS
  Mean apical root resorption was strongly correlated with total apical displacement (r = 0.822) and treatment duration (r = 0.852).
  
  
  CONCLUSIONS
  The treatment-related causes of root resorption appear to be the total distance the apex had moved and the time it took.
authors.affiliation: Department of Orthodontics, Temple University, Philadelphia, PA, USA. sgrsegal@aol.com
authors.forename: G R
authors.initials: GR
authors.lastname: Segal
authors.forename: P H
authors.initials: PH
authors.lastname: Schiffman
authors.forename: O C
authors.initials: OC
authors.lastname: Tuncay
mesh_terms: D003799:Dental Stress Analysis; D006801:Humans; D007180:Incisor; D008437:Maxilla; D012391:Root Resorption / Q000209:etiology*; D013997:Time Factors; D014087:Tooth Movement Techniques / Q000009:adverse effects*