title: Efficiency of Class II subdivision malocclusion treatment with 3 and 4 premolar extractions.
abstract: BACKGROUND
  In this study, we compared the efficiency of Class II subdivision malocclusion treatment with symmetric and asymmetric extractions.
  
  
  METHODS
  A sample of 71 patients with complete Class II subdivision malocclusion was selected: group 1 consisted of 40 patients treated with 4 premolar extractions with an initial mean age of 13.37 years, and group 2 had 31 patients treated with 3 premolar extractions (2 maxillary premolars and 1 mandibular premolar on the Class I side) with an initial mean age of 14.44 years. To compare the efficiency of each treatment protocol, the initial and final occlusal results were evaluated on dental casts with the Peer Assessment Rating occlusal index, and time spent in treatment was calculated from the clinical charts. The amounts of initial and final midline deviation and improvement of midline deviation correction were also evaluated. Efficiency was calculated as the rate between occlusal improvement by the treatment time. The groups were compared with t and Mann-Whitney tests.
  
  
  RESULTS
  The results showed that group 2 had a significantly smaller final amount of midline deviation and a greater correction of midline deviation.
  
  
  CONCLUSIONS
  Treatment efficiency of type 1 Class II subdivision malocclusions with 3 or 4 premolar extractions is similar. However, treatment with 3 premolar extractions provides a better occlusal success rate.
authors: Professor and head, Department of Orthodontics, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil. Electronic address: jansong@travelnet.com.br.
authors: Guilherme
authors: G
authors: Janson
authors: Postgraduate student, Department of Orthodontics, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil.
authors: Taiana
authors: T
authors: Baldo
authors: Associate professor, Department of Orthodontics, Bauru Dental School and Hospital for Rehabilitation of Craniofacial Anomalies, University of São Paulo, Bauru, São Paulo, Brazil.
authors: Daniela
authors: D
authors: Garib
authors: Associate professor, Department of Orthodontics, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
authors: Sérgio Estelita
authors: SE
authors: Barros
authors: Postgraduate student, Department of Orthodontics, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil.
authors: Raquel
authors: R
authors: Silva Poletto
authors: Postgraduate student, Department of Orthodontics, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil.
authors: Patricia
authors: P
authors: Bittencourt Dos Santos
mesh_terms: D000293:Adolescent; D001641:Bicuspid / Q000601:surgery*; D003767:Dental Occlusion, Balanced; D005260:Female; D006801:Humans; D008297:Male; D008310:Malocclusion / Q000145:classification* / Q000601:surgery* / Q000628:therapy; D008312:Malocclusion, Angle Class II / Q000175:diagnosis* / Q000601:surgery* / Q000628:therapy; D016896:Treatment Outcome