title: Efficiency of class I and class II malocclusion treatment with four premolar extractions.
abstract: Four premolar extractions is a successful protocol to treat Class I malocclusion, but it is a less efficient way when compared with other Class II treatment protocols.
  
  
  OBJECTIVE
  The objective of this study was to evaluate the influence of anteroposterior discrepancy on the success of four premolar extractions protocol. For that, treatment efficiency of Class I and complete Class II malocclusions, treated with four premolar extractions were compared.
  
  
  METHODS
  A sample of 107 records from 75 Class I (mean age of 13.98 years--group 1) and 32 Class II (mean age of 13.19 years--group 2) malocclusion patients treated with four premolar extractions was selected. The initial and final occlusal status of each patient was evaluated on dental casts with the PAR index. The treatment time was calculated based on the clinical charts, and the treatment efficiency was obtained by the ratio between the percentage of PAR reduction and treatment time. The PAR index and its components, the treatment time and the treatment efficiency of the groups were statistically compared with t tests and Mann-Whitney U-test.
  
  
  RESULTS
  The Class II malocclusion patients had a greater final PAR index than Class I malocclusion patients, and similar duration (Class I - 28.95 mo. and Class II - 28.10 mo.) and treatment efficiency.
  
  
  CONCLUSIONS
  The treatment of the complete Class II malocclusion with four premolar extractions presented worse occlusal results than Class I malocclusion owing to incomplete molar relationship correction.
authors.forename: Guilherme
authors.initials: G
authors.lastname: Janson
authors.forename: Alexandre
authors.initials: A
authors.lastname: Nakamura
authors.forename: Sérgio Estelita
authors.initials: SE
authors.lastname: Barros
authors.forename: Roberto
authors.initials: R
authors.lastname: Bombonatti
authors.forename: Kelly
authors.initials: K
authors.lastname: Chiqueto
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001641:Bicuspid / Q000601:surgery*; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008311:Malocclusion, Angle Class I / Q000628:therapy*; D008312:Malocclusion, Angle Class II / Q000628:therapy*; D012044:Regression Analysis; D012189:Retrospective Studies; D012690:Serial Extraction / Q000379:methods*; D012720:Severity of Illness Index; D012737:Sex Factors; D018709:Statistics, Nonparametric; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult