title: Factors related to alveolar bone thickness during upper incisor retraction.
abstract: OBJECTIVE
  To investigate the factors related to changes in alveolar bone thickness during upper incisor retraction.
  
  
  METHODS
  The subjects consisted of 23 ongoing orthodontic patients (mean age 20.4 ± 2.7 years) whose upper incisors were bound for retraction. Changes in alveolar bone thickness in the retracted area were assessed using preretraction (T0) and postretraction (T1) cone-beam computed tomography images. Labial bone thickness (LBT), palatal bone thickness (PBT), and total bone thickness (TBT) were assessed at the crestal, midroot, and apical levels of the retracted incisors. Paired t-tests were used to compare T0 and T1 bone thickness measurements. Spearman's rank correlation analysis was performed to determine the relationship of changes in alveolar bone thickness with the rate of tooth movement, change in inclination, initial alveolar bone thickness, and the extent of intrusion.
  
  
  RESULTS
  As the upper incisors were retracted, the LBT at the crestal level and TBT at the apical level significantly increased (P < .005). Changes in alveolar bone thickness were significantly associated with the rate of tooth movement, change in inclination, and extent of intrusion (P < .05) but not initial alveolar bone thickness (P > .05).
  
  
  CONCLUSIONS
  Rate of tooth movement, change in inclination, and extent of intrusion are significant factors that may influence alveolar bone thickness during upper incisor retraction. These factors must be carefully monitored to avoid the undesirable thickening of alveolar bone.
authors.affiliation: Orthodontic Section, Department of Preventive Dentistry, Faculty of Dentistry, Prince of Songkla University, Hat Yai, Songkhla, Thailand.
authors.forename: Nuengrutai
authors.initials: N
authors.lastname: Yodthong
authors.forename: Chairat
authors.initials: C
authors.lastname: Charoemratrote
authors.forename: Chidchanok
authors.initials: C
authors.lastname: Leethanakul
mesh_terms: D000293:Adolescent; D000328:Adult; D000539:Alveolar Process / Q000000981:diagnostic imaging / Q000502:physiology*; D016723:Bone Remodeling / Q000502:physiology*; D002508:Cephalometry / Q000379:methods; D054893:Cone-Beam Computed Tomography; D005260:Female; D006801:Humans; D007180:Incisor / Q000000981:diagnostic imaging; D008297:Male; D008437:Maxilla / Q000000981:diagnostic imaging*; D009967:Orthodontic Appliances; D014087:Tooth Movement Techniques / Q000009:adverse effects* / Q000379:methods