title: Tooth size and arch dimension in uncrowded versus crowded Class I malocclusions.
abstract: OBJECTIVE
  The purpose of this investigation was to examine the extent to which arch dimension or tooth size contributes to dental crowding.
  
  
  METHODS
  Two groups of dental casts were selected. Each group consisted of 30 pairs of dental casts including equal male and female samples. The first group had Class I malocclusions without crowding or spacing. The second group exhibited Class I malocclusions with severe dental crowding (> a 5 mm space deficiency). The following parameters were measured and used to compare the two groups: individual and collective mesiodistal tooth diameters, dental arch length, as well as buccal and lingual dental arch widths in the canine and molar regions. To compare the two groups the Student's t-test with 95% confidence interval was used.
  
  
  RESULTS
  Statistically significant differences in both tooth diameters and transverse arch dimensions were found between the two groups. The crowded group was found to have a significantly smaller maxillary arch width and larger tooth size when compared with the uncrowded group.
  
  
  CONCLUSIONS
  The results of this study suggest under equal conditions (a Class I skeletal relationship) tooth size has a greater role in developing dental crowding.
authors.affiliation: Department of Orthodontics, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran. poustimaryam@yahoo.com
authors.forename: Maryam
authors.initials: M
authors.lastname: Poosti
authors.forename: Tahereh
authors.initials: T
authors.lastname: Jalali
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D003724:Dental Arch / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D008297:Male; D008311:Malocclusion, Angle Class I / Q000473:pathology*; D003765:Models, Dental; D009811:Odontometry; D014070:Tooth / Q000033:anatomy & histology*