title: Mandibular anterior bony support and incisor crowding: Is there a relationship?
abstract: BACKGROUND
  The aim of this study was to test the null hypothesis that increased irregularity of the mandibular incisors is associated with a reduction in the alveolar support on cone-beam computed tomographic sections.
  
  
  METHODS
  From a sample of 1100 digital volumetric tomographs, 125 tomographs of subjects with Class I malocclusion (mean age, 21.6 ± 4.8 years) were selected for this study. An irregularity index was used to categorize these tomographs as having mild, moderate, or severe crowding. All tomographs were taken by using an iCAT (Imaging Sciences International, Hatfield, Pa) imaging device. The following parameters were measured on the sections corresponding to the 4 mandibular incisors with the iCAT software: height, thickness, and area of the entire symphysis; height, thickness, and area of the cancellous bone of the symphysis; and distance between the vestibular and lingual cortices. For the statistical evaluation, independent samples t test, analysis of variance, and the Tukey HSD test were used at an alpha level 0.05. The Pearson correlation coefficient and a simple linear regression were calculated to determine the relationship between mandibular anterior bony support and incisor crowding.
  
  
  RESULTS
  Almost all mandibular anterior bone measurements were greater in the male subjects than in the female subjects (height of the mandibular symphysis, P <0.001; cancellous bone height, P <0.001). Female subjects with mild crowding had higher values for cancellous bone height (P = 0.025) and vestibular cancellous bone thickness (P = 0.004) than did those with severe crowding. However, no differences were detected in the male subjects. Additionally, significant correlations were determined between incisor crowding and thickness of the mandibular symphysis, cancellous bone thickness, and the vestibular part of cancellous bone thickness in female subjects.
  
  
  CONCLUSIONS
  Significant relationships were found between the measures of mandibular incisor crowding and basal bone dimensions in female subjects. Except for the vestibular part of cancellous bone thickness, all mandibular incisor bone measurements were greater in the male subjects than in the female subjects.
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, Izmir Katip Celebi University, Izmir, Turkey. tancanuysal@yahoo.com
authors.forename: Tancan
authors.initials: T
authors.lastname: Uysal
authors.forename: Ahmet
authors.initials: A
authors.lastname: Yagci
authors.forename: Torun
authors.initials: T
authors.lastname: Ozer
authors.forename: Ilknur
authors.initials: I
authors.lastname: Veli
authors.forename: Ahmet
authors.initials: A
authors.lastname: Ozturk
mesh_terms: D000293:Adolescent; D000328:Adult; D016301:Alveolar Bone Loss / Q000150:complications* / Q000000981:diagnostic imaging; D000704:Analysis of Variance; D015519:Bone Density; D002508:Cephalometry; D002680:Chin / Q000473:pathology; D054893:Cone-Beam Computed Tomography; D005260:Female; D006801:Humans; D007180:Incisor / Q000473:pathology*; D016014:Linear Models; D008297:Male; D008311:Malocclusion, Angle Class I / Q000209:etiology* / Q000473:pathology*; D008336:Mandibular Diseases / Q000150:complications* / Q000000981:diagnostic imaging; D012737:Sex Factors; D018709:Statistics, Nonparametric; D055815:Young Adult