title: Skeletal and dental changes after rapid maxillary expansion: a computed tomography study.
abstract: OBJECTIVE
  To investigate the skeletal and dental changes induced by rapid maxillary expansion, using computed tomography (CT) scans and three-dimensional (3-D) reconstructed images.
  
  
  METHODS
  Twenty patients (Mean age: 12.3 +/- 1.9 years) who required rapid maxillary expansion as a part of their comprehensive orthodontic treatment underwent pretreatment (T1) and post-treatment (T2) CT scans. The T2--T1 differences between selected skeletal and dental measurements on the coronal CT and 3-D volumetric images were compared using the Wilcoxon signed ranks test.
  
  
  RESULTS
  At T2 the Maxillary alveolar width (4.5 +/- 3.5 mm) was greater than the Maxillary base width (1.7 +/- 0.9 mm). The greatest transverse dental change was in the Intermolar width (6.3 +/- 2.1 mm and 2.7 +/- 1.9 mm at the crown and the apex, respectively). On the 3-D volume, significant increases occurred in the Bicondylar width (1.2 +/- 1.3 mm), Bimaxillo-mandibular width (2.1 +/- 2.3 mm) and the Maxillary width (2.5 +/- 1.6 mm). The greatest change in the dental measurements was in the Maxillary first molar width (6.4 +/- 0.1 mm). The Maxillary central incisor angle decreased significantly (-7.9 +/- 8.4 mm), indicating an increase in the distance between the apices of the central incisors.
  
  
  CONCLUSIONS
  Volumetric 3-D CT scanning provides a useful method for assessing skeletal and dental changes after rapid maxillary expansion. Although significant increases occurred in most skeletal and dental measures, it appears that dental tipping explains most of the expansion.
authors.affiliation: Department of Orthodontics, Al-Azhar University Faculty of Dental Medicine, Cairo, Egypt. aghoneim@iupui.edu
authors.forename: Ahmed
authors.initials: A
authors.lastname: Ghoneima
authors.forename: Ezzat
authors.initials: E
authors.lastname: Abdel-Fattah
authors.forename: Francisco
authors.initials: F
authors.lastname: Eraso
authors.forename: David
authors.initials: D
authors.lastname: Fardo
authors.forename: Katherine
authors.initials: K
authors.lastname: Kula
authors.forename: James
authors.initials: J
authors.lastname: Hartsfield
mesh_terms: D000293:Adolescent; D000539:Alveolar Process / Q000000981:diagnostic imaging; D001641:Bicuspid / Q000000981:diagnostic imaging; D002508:Cephalometry / Q000379:methods; D002648:Child; D003481:Cuspid / Q000000981:diagnostic imaging; D003724:Dental Arch / Q000000981:diagnostic imaging; D005147:Facial Bones / Q000000981:diagnostic imaging*; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D007180:Incisor / Q000000981:diagnostic imaging; D008310:Malocclusion / Q000000981:diagnostic imaging / Q000628:therapy; D008334:Mandible / Q000000981:diagnostic imaging; D008335:Mandibular Condyle / Q000000981:diagnostic imaging; D008437:Maxilla / Q000000981:diagnostic imaging; D008963:Molar / Q000000981:diagnostic imaging; D016382:Orthodontic Appliance Design; D010155:Palatal Expansion Technique / Q000295:instrumentation; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014070:Tooth / Q000000981:diagnostic imaging*; D019227:Tooth Apex / Q000000981:diagnostic imaging; D019228:Tooth Crown / Q000000981:diagnostic imaging