title: Rotation of the upper first molar in Class I, II, and III patients.
abstract: OBJECTIVE
  The aim of this study was to evaluate the mean rotation of the upper first molar (U1(st) M) in cast models from nontreated patients presenting: Class I, skeletal Class II, dental Class II, and skeletal Class III, comparing with Class I orthodontically treated patients.
  
  
  METHODS
  One hundred cast models were evaluated with five groups, composed of nontreated Class I (n = 20), dental Class II (n = 20), skeletal Class II (n = 20), skeletal Class III (n = 20), and treated Class I (n = 20). Measurements were taken from photocopies of the upper arches. The angle formed between a line crossing the mesiopalatal and the distal-buccalcusps of the U1(st) M and a line traced on mid palatal junction were measured in all samples.
  
  
  RESULTS
  One-way variance analysis showed that dental Class II group presented great mean rotation of the 1(st) molar (x = 78.95°, SD = 6.19) (P < 0.05), and in 85% of the patients from this group this angle was higher than 73°.
  
  
  CONCLUSIONS
  The skeletal Class II and skeletal Class III groups showed similar mean position of the 1(st) molar, presenting rotation in approximately 50% of the patients. It can be concluded that upper molar rotation occurs mainly in dental Class II patients and shows higher mesial rotation angle.
authors.affiliation: Private Office, Campo Erê, SC, Brazil.
authors.forename: Cristiane de Oliveira
authors.initials: CO
authors.lastname: Viganó
authors.affiliation: Private Office, Cidade Gaúcha, PR, Brazil.
authors.forename: Viviane Ekerman
authors.initials: VE
authors.lastname: da Rocha
authors.affiliation: Private Office, Lagarto, SE, Brazil.
authors.forename: Laerte Ribeiro Menezes
authors.initials: LRM
authors.lastname: Junior
authors.affiliation: Department of Dentistry, Federal University of Sergipe, Lagarto, SE, Brazil.
authors.forename: Luiz Renato
authors.initials: LR
authors.lastname: Paranhos
authors.affiliation: Department of Orthodontics, State University of Maringá, Maringá, PR, Brazil.
authors.forename: Adilson Luiz
authors.initials: AL
authors.lastname: Ramos
keywords: Angle Class II; malocclusion; molar; rotation