title: Overjet correction and space closure mechanisms for Class II treatment by extracting the maxillary first molars.
abstract: OBJECTIVE
  To analyze the mechanism of overjet correction and space closure when treating Class II Division 1 patients by extracting the maxillary first molars.
  
  
  METHODS
  A total of 100 prospective, consecutively treated Class II Division 1 patients (45 female, 55 male; 10.5-17.2 years old). Standardized lateral cephalograms prior to and after treatment were evaluated via a modified sagittal occlusion analysis (SO analysis).
  
  
  RESULTS
  The mean degree of overjet correction was 5.2 mm (95% CI = 4.8-5.6 mm) and was on average achieved by means of 1.7 mm skeletal and 3.5 mm dental changes. The relationship between the premolars improved by 4.8 mm toward a Class I relationship, facilitated by 1.7 mm skeletal and 3.1 mm dental changes. The 11.3 mm space closure in the maxillary first-molar extraction area resulted from distalization of the second premolars (1.4 mm) and a mesialization of the second molars (9.9 mm).
  
  
  CONCLUSIONS
  Overjet correction was essentially achieved by a retrusion of the upper incisors, as well as by ventral growth of the lower jaw and protrusion of the lower incisors. Space closure was only partly achieved by distalization of the premolars.
authors: Department of Orthodontics and Oral Biology, Radboud University Nijmegen, Medical Center, Nijmegen, The Netherlands.
authors: Johan W
authors: JW
authors: Booij
authors: Juliane
authors: J
authors: Goeke
authors: Ewald M
authors: EM
authors: Bronkhorst
authors: Hans
authors: H
authors: Pancherz
authors: Sabine
authors: S
authors: Ruf
authors: Christos
authors: C
authors: Katsaros
mesh_terms: D000293:Adolescent; D002648:Child; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D008297:Male; D008312:Malocclusion, Angle Class II / Q000150:complications* / Q000628:therapy*; D008963:Molar / Q000601:surgery*; D009971:Orthodontics, Corrective; D057887:Overbite / Q000150:complications* / Q000628:therapy*; D014081:Tooth Extraction / Q000379:methods*; D016896:Treatment Outcome