title: Mesial rotation of upper first molars in Class II division 1 malocclusion in the mixed dentition: a controlled blind study.
abstract: OBJECTIVE
  To compare the amount of upper molar rotation in subjects with Class II Division 1 malocclusion and subjects with normal occlusion in the intermediate and late mixed dentition phases.
  
  
  METHODS
  Dental cast measurements were performed in a sample of 120 Class II Division 1 subjects (CL2 group, 67 females and 53 males, mean age 9.4±1.1 years), and in a sample of 58 Class I subjects (CL1 group, 34 females and 24 males, mean age 9.7±1.2 years). Independent sample t tests were used for statistical comparisons (P<.05).
  
  
  RESULTS
  The amount of upper molar rotation was significantly greater in CL2 group when compared with CL1 group as assessed by both the mesial and buccal molar cusp angles. No differences were found with regard to upper or lower arch depths, or upper intercanine width. CL2 group showed a significant deficiency in upper intermolar width along with a significant posterior transverse interarch discrepancy when compared with CL1 group.
  
  
  CONCLUSIONS
  Subjects with Class II malocclusion in the mixed dentition present with mesial upper molar rotation in about 84% of the cases. The correction of molar rotation may provide between 1 and 2mm of gain in arch perimeter and of improvement in molar relationships per side in 5 out 6 Class II patients.
authors.affiliation: Department of Orthodontics, The University of Florence, Italy.
authors.forename: Veronica
authors.initials: V
authors.lastname: Giuntini
authors.forename: Tiziano
authors.initials: T
authors.lastname: Baccetti
authors.forename: Efisio
authors.initials: E
authors.lastname: Defraia
authors.forename: Paola
authors.initials: P
authors.lastname: Cozza
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Franchi
mesh_terms: D002648:Child; D003818:Dentition, Mixed; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008312:Malocclusion, Angle Class II / Q000150:complications*; D008437:Maxilla; D008644:Mesial Movement of Teeth / Q000150:complications*; D008963:Molar / Q000503:physiopathology*; D009811:Odontometry; D014087:Tooth Movement Techniques / Q000379:methods*