title: Influence of Invisalign treatment with interproximal enamel reduction (IER) on bone volume for adult crowding: a retrospective three-dimensional cone beam computed tomography study.
abstract: BACKGROUND
  The aim of this study was to use three-dimensional datasets to identify associations between treatment for adult crowding using Invisalign and interproximal enamel reduction (IER) and changes in the bone volume.
  
  
  METHODS
  A total of 60 digital cone beam computed tomography (CBCT) scans from 30 patients (28 women, two men; 30 CBCTs pretreatment, 30 posttreatment) were examined retrospectively in order to record bone volume three-dimensionally before and after treatment. The patients' average age was 36.03 ± 9.7 years. The data were collected and analyzed using the computer programs Mimics 15.0 and OsiriX. Differences in bone between T0 and T1 were analyzed with IBM SPSS 21.0 using the Wilcoxon test for paired samples.
  
  
  RESULTS
  Analysis of the orovestibular bone volume showed highly significant changes (bone change P <0.001) only in the mandible where more expansion of the dental arch was carried out using proclination or protrusion. The bone lamella was thinner buccally and thicker lingually. In general, bone increases in the oral direction were slightly greater than bone losses in the vestibular direction. No significant changes were detected in the maxilla (bone change P = 0.13). Significant vertical bone loss in the bone height was detected in both the maxilla and the mandible. The largest bone loss was observed in the vestibular direction in the mandible, at a high level of significance (P <0.001).
  
  
  CONCLUSIONS
  Particularly in the mandible, therapeutic reduction of the vertical and sagittal bone volume shows that caution should be used in the treatment of tertiary crowding with proclination and expansion. The cortical walls appear to represent the limits for orthodontic tooth movement, at least in adult female patients.
authors: Department of Orthodontics, University Hospital Giessen and Marburg, Campus Marburg, Georg-Voigt-Strasse 3, Marburg, 35039, Germany. hellak@med.uni-marburg.de.|Abt. für Kieferorthopädie, UKGM Standort Marburg, Georg-Voigt-Strasse 3, 35039, Marburg, Germany. hellak@med.uni-marburg.de.
authors: Andreas
authors: A
authors: Hellak
authors: Department of Orthodontics, University Hospital Giessen and Marburg, Campus Marburg, Georg-Voigt-Strasse 3, Marburg, 35039, Germany.
authors: Nicola
authors: N
authors: Schmidt
authors: Department of Orthodontics, University Hospital Giessen and Marburg, Campus Marburg, Georg-Voigt-Strasse 3, Marburg, 35039, Germany.
authors: Michael
authors: M
authors: Schauseil
authors: Department of Orthodontics, University Hospital Giessen and Marburg, Campus Marburg, Georg-Voigt-Strasse 3, Marburg, 35039, Germany.
authors: Steffen
authors: S
authors: Stein
authors: Private practice, Wiesbaden, Germany.
authors: Thomas
authors: T
authors: Drechsler
authors: Department of Orthodontics, University Hospital Giessen and Marburg, Campus Marburg, Georg-Voigt-Strasse 3, Marburg, 35039, Germany.
authors: Heike Maria
authors: HM
authors: Korbmacher-Steiner
mesh_terms: D000328:Adult; D000539:Alveolar Process; D002508:Cephalometry; D054893:Cone-Beam Computed Tomography; D003743:Dental Enamel; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D008334:Mandible; D008437:Maxilla; D009967:Orthodontic Appliances; D012189:Retrospective Studies; D014087:Tooth Movement Techniques
keywords: Adult crowding; Bone quantity; CBCT; Interproximal enamel reduction (IER); Invisalign; Landmarks; Recessions