title: Class II subdivision malocclusion types and evaluation of their asymmetries.
abstract: BACKGROUND
  The primary objective of this study was to determine, by means of frontal photographic evaluation, the distribution of the 2 main types of Class II subdivision malocclusions. The secondary objective was to compare the dentoskeletal asymmetries in these 2 types with a group of normal-occlusion subjects by using submentovertex and posteroanterior radiographs.
  
  
  METHODS
  The experimental group included 44 untreated Class II subdivision malocclusion subjects with a mean age of 15.3 years. The control group included 30 subjects with normal occlusions with a mean age of 22.4 years. All had full complements of permanent teeth up to the first molars and had not received orthodontic treatment. Type 1 Class II subdivision malocclusion is coincidence of the maxillary dental midline with the facial midline and deviation of the mandibular midline. Type 2 has the opposite characteristics. The frontal photographs were evaluated subjectively by 2 examiners. In the submentovertex and posteroanterior radiographs, symmetry was assessed by measuring the relative difference in the spatial positions of dentoskeletal landmarks between the right and left sides. Independent t tests were used to compare the dentoskeletal asymmetries of types 1 and 2 with the normal-occlusion group.
  
  
  CONCLUSIONS
  The results showed that 61.36% had type 1, 18.18% had type 2 Class II subdivision malocclusion, and 20.45% had mixed characteristics. The predominant asymmetric dentoalveolar characteristics of both types of Class II subdivision malocclusions were evident when individually compared with a normal-occlusion control group. There was a tendency for the type 1 subjects to have greater mandibular asymmetry than type 2, as compared with the control group.
authors.affiliation: Department of Orthodontics, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil. jansong@travelnet.com.br
authors.forename: Guilherme
authors.initials: G
authors.lastname: Janson
authors.forename: Karina Jerônimo Rodrigues Santiago
authors.initials: KJ
authors.lastname: de Lima
authors.forename: Donald G
authors.initials: DG
authors.lastname: Woodside
authors.forename: Angelos
authors.initials: A
authors.lastname: Metaxas
authors.forename: Marcos Roberto
authors.initials: MR
authors.lastname: de Freitas
authors.forename: José Fernando Castanha
authors.initials: JF
authors.lastname: Henriques
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002508:Cephalometry / Q000706:statistics & numerical data; D002648:Child; D005146:Facial Asymmetry / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008312:Malocclusion, Angle Class II / Q000145:classification* / Q000473:pathology*; D023861:Photography, Dental; D011861:Radiography, Dental