title: [Evaluation of alveolar bone defects on anterior region in patients with bimaxillary protrusion by using cone-beam CT].
abstract: OBJECTIVE
  To investigate the alveolar bone defects of anterior alveolar bone in patients with bimaxillary protrusion by using cone-beam computed tomography (CBCT).
  
  
  METHODS
  The samples consisted of 50 patients with bimaxillary protrusion, who were assigned to the teenage group[20 cases, (13.1±1.0) years] and adult group[30 cases, (22.9±4.2) years]. The adult group included 9 hypo-divergent, 11 normo-divergent and 10 hyper-divergent patients. The images were obtained by using NewTom VG CBCT and the alveolar defects were evaluated.
  
  
  RESULTS
  The ratio of the patients had alveolar bone defects was 94.00%. Meanwhile, the defects were associated with 38.60% of all the teeth. Most defects occurred on labial alveolar bone (98.66%); fenestration was found more in the maxillary alveolar region and dehiscence occurred more in the mandible. The dehiscences (3.06%) and defects prevalence (30.13%) of the teenage group were significant lower than those of the adult group (11.73% vs. 42.46%), P<0.05; while there was no significance of the fenestrations prevalence between the two group (P>0.05). The hypo-divergent group had lower fenestrations prevalence (22.22%) than the normo-divergent (33.84%) and hyper-divergent groups (37.50%), P<0.05. The upper central incisor had the lowest alveolar bone defect prevalence.
  
  
  CONCLUSIONS
  Alveolar bone defects are common findings in patients with bimaxillary protrusion before orthodontic treatment. The prevalence of defects is affected by age and vertical-growth type.
authors.affiliation: Fifth Clinical Division, Peking University School and Hospital of Stomatology, Beijing 100020,China.
authors.forename: Lin
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing 100081, China.
authors.forename: Wei-ran
authors.initials: WR
authors.lastname: Li
mesh_terms: D000293:Adolescent; D000328:Adult; D000539:Alveolar Process / Q000000981:diagnostic imaging* / Q000473:pathology*; D054893:Cone-Beam Computed Tomography; D006801:Humans; D008310:Malocclusion / Q000175:diagnosis*; D008334:Mandible; D014070:Tooth; D055815:Young Adult