title: Factors affecting buccal bone changes of maxillary posterior teeth after rapid maxillary expansion.
abstract: BACKGROUND
  The purpose of this study was to use cone-beam computed tomography (CBCT) images to determine the factors that might affect buccal bone changes of maxillary posterior teeth after rapid maxillary expansion (RME).
  
  
  METHODS
  Thirty consecutive patients (17 boys, 13 girls; mean age, 13.8 +/- 1.7 years) who required RME as part of their orthodontic treatment and had the pre-RME (T1) and post-RME (T2) CBCT images available were included in the study. The T1 and T2 measurements of interdental distance, interdental angle (IA), buccal bone thickness (BBT), and buccal marginal bone levels (BMBL) of the first premolar (P1), the second premolar (P2), and the first molar (M1) were compared with the Friedman and the Wilcoxon signed rank tests. To determine which variables were associated with the changes in IA, BBT, and BMBL, the Spearman rank correlation analysis was performed (alpha = .05).
  
  
  CONCLUSIONS
  The results suggest that buccal crown tipping, and reduction of BBT and BMBL of the maxillary posterior teeth are the expected immediate effects of RME. There were no significant differences in dental expansion among P1, P2, and M1 (P >.05). P2 had clinically more buccal crown tipping (P = .116) but statistically less reduction in BBT and BMBL (P <.0001 and P = .001) than P1 and M1. Buccal bone changes and dental tipping on P2 were not affected by any other variables. Factors that showed significant correlation to buccal bone changes and dental tipping on P1 and M1 were age, appliance expansion, initial buccal bone thickness, and differential expansion (P <.05), but rate of expansion and retention time had no significant association (P >.05).
authors.affiliation: Department of Orthodontics, School of Dentistry, Loma Linda University, Loma Linda, Calif 92354, USA. rungkit@msn.com
authors.forename: Kitichai
authors.initials: K
authors.lastname: Rungcharassaeng
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Caruso
authors.forename: Joseph Y K
authors.initials: JY
authors.lastname: Kan
authors.forename: Jay
authors.initials: J
authors.lastname: Kim
authors.forename: Guy
authors.initials: G
authors.lastname: Taylor
mesh_terms: D000293:Adolescent; D000367:Age Factors; D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging / Q000209:etiology*; D001641:Bicuspid / Q000503:physiopathology; D015519:Bone Density; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008437:Maxilla / Q000000981:diagnostic imaging / Q000503:physiopathology; D008439:Maxillary Diseases / Q000000981:diagnostic imaging / Q000209:etiology; D008963:Molar / Q000503:physiopathology; D009967:Orthodontic Appliances / Q000009:adverse effects; D010155:Palatal Expansion Technique / Q000009:adverse effects* / Q000295:instrumentation; D011861:Radiography, Dental / Q000379:methods; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods; D019228:Tooth Crown / Q000503:physiopathology