title: Stability of class II subdivision malocclusion treatment with 3 and 4 premolar extractions.
abstract: BACKGROUND
  The purpose of this study was to compare the occlusal stability of class II subdivision malocclusion treatment with 3 and 4 first premolar extractions. A sample of 156 dental casts from 52 patients with class II subdivision malocclusion was divided into two groups according to the extraction protocol. Group 1 comprised 24 patients treated with 3 premolar extractions and group 2 included 28 patients treated with 4 premolar extractions.
  
  
  METHODS
  Peer assessment rating (PAR) indexes were measured on the dental casts obtained before (T1) and after treatment (T2) and at a mean of 6.9 years after the end of treatment (T3). The groups were matching regarding sex distribution, pretreatment, posttreatment and long-term posttreatment ages, and treatment and long-term posttreatment times. They were also comparable concerning the initial malocclusion severity and the occlusal results at the end of treatment. Stability evaluation was calculated by subtracting the posttreatment from the long-term posttreatment index values (T3 - T2). T tests were used to compare the amount and percentage of long-term posttreatment changes.
  
  
  RESULTS
  There were no intergroup differences regarding the amount and percentage of long-term posttreatment changes.
  
  
  CONCLUSIONS
  Treatment of class II subdivision malocclusion with 3 and 4 premolar extractions have a similar long-term posttreatment occlusal stability.
authors.affiliation: Department of Orthodontics, Bauru Dental School, University of São Paulo, Alameda Octávio Pinheiro Brisolla 9-75, Bauru 17012-901, São Paulo , Brazil. jansong@travelnet.com.br.
authors.forename: Guilherme
authors.initials: G
authors.lastname: Janson
authors.forename: Janine
authors.initials: J
authors.lastname: Araki
authors.forename: Sérgio
authors.initials: S
authors.lastname: Estelita
authors.forename: Leonardo T
authors.initials: LT
authors.lastname: Camardella
mesh_terms: D000293:Adolescent; D000328:Adult; D001641:Bicuspid / Q000473:pathology / Q000601:surgery*; D003481:Cuspid / Q000473:pathology; D005115:Extraoral Traction Appliances; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008312:Malocclusion, Angle Class II / Q000145:classification / Q000628:therapy*; D003765:Models, Dental; D008963:Molar / Q000473:pathology; D016910:Orthodontic Brackets; D018704:Orthodontic Retainers; D009969:Orthodontic Wires; D057887:Overbite / Q000628:therapy; D012189:Retrospective Studies; D014081:Tooth Extraction / Q000295:instrumentation / Q000379:methods*; D014087:Tooth Movement Techniques / Q000295:instrumentation; D016896:Treatment Outcome; D055815:Young Adult