title: Comparison of occlusal contact areas of class I and class II molar relationships at finishing using three-dimensional digital models.
abstract: OBJECTIVE
  This study compared occlusal contact areas of ideally planned set-up and accomplished final models against the initial in class I and II molar relationships at finishing.
  
  
  METHODS
  Evaluations were performed for 41 post-orthodontic treatment cases, of which 22 were clinically diagnosed as class I and the remainder were diagnosed as full cusp class II. Class I cases had four first premolars extracted, while class II cases had maxillary first premolars extracted. Occlusal contact areas were measured using a three-dimensional scanner and RapidForm 2004. Independent t-tests were used to validate comparison values between class I and II finishings. Repeated measures analysis of variance was used to compare initial, set up, and final models.
  
  
  RESULTS
  Molars from cases in the class I finishing for the set-up model showed significantly greater contact areas than those from class II finishing (p < 0.05). The final model class I finishing showed significantly larger contact areas for the second molars (p < 0.05). The first molars of the class I finishing for the final model showed a tendency to have larger contact areas than those of class II finishing, although the difference was not statistically significant (p = 0.078).
  
  
  CONCLUSIONS
  In set-up models, posterior occlusal contact was better in class I than in class II finishing. In final models, class I finishing tended to have larger occlusal contact areas than class II finishing.
authors.affiliation: Department of Dentistry, Graduate School of Medicine, Ewha Womans University, Seoul, Korea.
authors.forename: Hyejoon
authors.initials: H
authors.lastname: Lee
authors.affiliation: Department of Dentistry, Graduate School of Medicine, Ewha Womans University, Seoul, Korea.
authors.forename: Minji
authors.initials: M
authors.lastname: Kim
authors.affiliation: Department of Dentistry, Graduate School of Medicine, Ewha Womans University, Seoul, Korea.
authors.forename: Youn-Sic
authors.initials: YS
authors.lastname: Chun
keywords: Contact area; Molar; Occlusion; Orthodontic treatment; Tooth movement