title: Long-term stability of Class II malocclusion treated with 2- and 4-premolar extraction protocols.
abstract: BACKGROUND
  The objective of this study was to cephalometrically compare the stability of complete Class II malocclusion treatment with 2 or 4 premolar extractions after a mean period of 9.35 years.
  
  
  METHODS
  A sample of 57 records from patients with complete Class II malocclusion was selected and divided into 2 groups. Group 1 consisted of 30 patients with an initial mean age of 12.87 years treated with extraction of 2 maxillary premolars. Group 2 consisted of 27 patients with an initial mean age of 13.72 years treated with extraction of 4 premolars. T tests were used to compare the groups' initial cephalometric characteristics and posttreatment changes. Pearson correlation coefficients were calculated to determine the correlation between treatment and posttreatment dental-relationship changes.
  
  
  RESULTS
  During the posttreatment period, both groups had similar behavior, except that group 1 had a statistically greater maxillary forward displacement and a greater increase in the apical-base relationship than group 2. On the other hand, group 2 had a statistically greater molar-relationship relapse toward Class II. There were significant positive correlations between the amounts of treatment and posttreatment dentoalveolar-relationship changes.
  
  
  CONCLUSIONS
  Treatment of complete Class II malocclusions with 2 maxillary premolar extractions or 4 premolar extractions had similar long-term posttreatment stability.
authors: Department of Orthodontics, Bauru Dental School, University of São Paulo, Bauru, SP, Brazil. jansong@travelnet.com.br
authors: Guilherme
authors: G
authors: Janson
authors: Vladimir
authors: V
authors: Leon-Salazar
authors: Ruben
authors: R
authors: Leon-Salazar
authors: Marcos
authors: M
authors: Janson
authors: Marcos Roberto
authors: MR
authors: de Freitas
mesh_terms: D000293:Adolescent; D001641:Bicuspid / Q000601:surgery; D002508:Cephalometry / Q000706:statistics & numerical data; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008312:Malocclusion, Angle Class II / Q000628:therapy*; D009971:Orthodontics, Corrective / Q000379:methods*; D012008:Recurrence; D012189:Retrospective Studies; D014081:Tooth Extraction; D055815:Young Adult