title: Three-dimensional computed tomography comparison of the maxillary palatal vault between patients with rapid palatal expansion and orthodontically treated controls.
abstract: BACKGROUND
  The aim of this study was to use cone-beam computed tomography to compare changes of skeletal and dental structures of the maxillary palatal vault in a group of growing patients treated for posterior crossbite before and after rapid palatal expansion (RPE) with changes over time in a control group.
  
  
  METHODS
  The sample for this retrospective study included 19 patients treated with a hyrax palatal expander at a graduate orthodontic clinic and 19 control subjects who received no RPE. Beginning and progress cone-beam computed tomography scans of all patients were analyzed to measure the anatomic volume, width, height, and anteroposterior dimensions of the palatal region.
  
  
  RESULTS
  Progress scans (after RPE treatment for cases) showed, the mean percentages of change in palatal volume were 10.8% in the controls and 21.7% in the RPE group (P = 0.038); however, there were no statistically significant differences in palatal volume at baseline or at progress scan between the RPE patients and controls. Absolute first molar-to-molar width changes at progress scan were 0.57 mm in the controls and 3.27 mm in the RPE group (P = 0.022). Absolute canine-to-canine width changes at progress scan were 0.45 mm in the controls and 2.79 mm in the RPE group (P = 0.007). There were significant differences in percentage and absolute changes in maxillary width measured from molar to molar and canine to canine between RPE group and controls, but no significant differences in maxillary vault height or anteroposterior dimension changes.
  
  
  CONCLUSIONS
  At progress scan, canine-to-canine width, first molar-to-molar width, and anteroposterior length of the palatal maxillary volume in the RPE group approached the measurements of the controls. Palatal volumes (at baseline and progress scan) were not statistically significantly different between the groups.
authors.affiliation: Resident, Department of Orthodontics, School of Dentistry, University of Southern California, Los Angeles, Calif.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Gohl
authors.affiliation: Lecturer, School of Dentistry, University of Southern California, Los Angeles, Calif.
authors.forename: Manuel
authors.initials: M
authors.lastname: Nguyen
authors.affiliation: Clinical assistant professor, Division of Craniofacial Sciences and Therapeutics, School of Dentistry, University of Southern California, Los Angeles, Calif. Electronic address: renciso@usc.edu.
authors.forename: Reyes
authors.initials: R
authors.lastname: Enciso
mesh_terms: D000293:Adolescent; D002648:Child; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D008310:Malocclusion / Q000628:therapy; D008437:Maxilla / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D009971:Orthodontics, Corrective; D010155:Palatal Expansion Technique / Q000295:instrumentation; D021362:Palate, Hard / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D018709:Statistics, Nonparametric