title: Stability of extraction space closure.
abstract: BACKGROUND
  The objectives of this study were to evaluate the prevalence and long-term behavior of extraction space reopening in patients with Class I malocclusion and to identify some associated factors.
  
  
  METHODS
  A sample of 43 patients met the inclusion criteria. Dental casts at the onset of treatment, after treatment, and 1 and 5 years after debonding were used. Initial and final cephalometric radiographs were used to measure the amount of incisor retraction. Cochran tests were used to compare the numbers of open and closed extraction spaces after treatment and at 1 and 5 years after debonding (P <0.05). Initial incisor crowding, amounts of anterior retraction, and angulations between the canines and the second premolars were compared between patients with and without space reopening with t tests.
  
  
  RESULTS
  Of the sample, 30.23% had extraction space reopening. The frequency of open spaces significantly increased between the final and the 1-year posttreatment dental casts and decreased between the casts at 1 and 5 years posttreatment. Patients with space reopening had less initial anterior crowding and greater amounts of mandibular incisor retraction during treatment.
  
  
  CONCLUSIONS
  There was a high prevalence of space reopening 1 year after treatment. However, these spaces tended to decrease by 5 years after treatment.
authors.affiliation: Associate professor, Department of Orthodontics, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil.
authors.forename: Daniela Gamba
authors.initials: DG
authors.lastname: Garib
authors.affiliation: Postgraduate student, Department of Orthodontics, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil. Electronic address: larissa_bressane@hotmail.com.
authors.forename: Larissa Borges
authors.initials: LB
authors.lastname: Bressane
authors.affiliation: Professor, Department of Orthodontics, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil.
authors.forename: Guilherme
authors.initials: G
authors.lastname: Janson
authors.affiliation: Private practice, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Bruno Frazão
authors.initials: BF
authors.lastname: Gribel
mesh_terms: D000293:Adolescent; D001641:Bicuspid / Q000473:pathology / Q000601:surgery; D002508:Cephalometry / Q000379:methods; D002648:Child; D003481:Cuspid / Q000473:pathology; D003724:Dental Arch / Q000473:pathology; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007180:Incisor / Q000473:pathology; D008311:Malocclusion, Angle Class I / Q000628:therapy*; D008334:Mandible / Q000473:pathology; D008437:Maxilla / Q000473:pathology; D018704:Orthodontic Retainers; D019516:Orthodontic Space Closure / Q000145:classification* / Q000706:statistics & numerical data; D014081:Tooth Extraction / Q000379:methods*; D014087:Tooth Movement Techniques / Q000379:methods; D016896:Treatment Outcome