title: Three-dimensional evaluation of surgically assisted implant bone-borne rapid maxillary expansion: a pilot study.
abstract: BACKGROUND
  The purpose of this study was to evaluate 3-dimensional changes in dental, alveolar, and skeletal structures caused by a bone-borne implant-supported rapid maxillary expansion device (Dresden distractor).
  
  
  METHODS
  Axial computed tomography scans of 10 patients (mean age, 25.3 years) treated with the Dresden distractor were examined. Scans were taken immediately before and 9 months after expansion. Distances in all 3 dimensions were calculated for 38 skeletal, alveolar, and dental landmarks with respect to the reference point ELSA (point equidistant to both foramina spinosa).
  
  
  RESULTS
  In the transverse dimension, a V-shaped opening of the suture was shown; the greatest amount of opening was anteriorly directed, with convergence of the suture opening in the posterior aspect of the palate. The expansion of the maxillary dental arch showed a V pattern similar to the opening of the suture. In the frontal view, expansion caused a wedge-shaped opening with its base at the central incisors and the estimated center of rotation next to the frontonasal suture. The alveolar processes tipped buccally (9.9 degrees to 13.3 degrees) as did the molars (2.5 degrees to 3.5 degrees) and the premolars (3.0 degrees to 3.9 degrees). Less tipping of teeth compared with skeletal tipping (about 6 degrees to 9 degrees less) is related to the torque effect of the fixed appliance.
  
  
  CONCLUSIONS
  The Dresden distractor is a minimally invasive bone-borne expansion appliance that protects teeth by inducing more skeletal than dental changes. This might be a precondition for stable postsurgical occlusion.
authors: Department of Orthodontics, Technical University, Dresden, Germany.
authors: Eve
authors: E
authors: Tausche
authors: Lars
authors: L
authors: Hansen
authors: Volker
authors: V
authors: Hietschold
authors: Manuel O
authors: MO
authors: Lagravère
authors: Winfried
authors: W
authors: Harzer
mesh_terms: D000293:Adolescent; D000328:Adult; D000539:Alveolar Process / Q000033:anatomy & histology; D003799:Dental Stress Analysis; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008644:Mesial Movement of Teeth; D019647:Oral Surgical Procedures / Q000379:methods*; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D016382:Orthodontic Appliance Design; D009967:Orthodontic Appliances; D010155:Palatal Expansion Technique / Q000295:instrumentation*; D021362:Palate, Hard / Q000033:anatomy & histology; D010865:Pilot Projects; D036542:Tomography, Spiral Computed