title: Assessing bone volume for orthodontic miniplate fixation below the maxillary frontal process.
abstract: OBJECTIVE
  The maxillary bone below the frontal process is used for orthodontic anchorage; indications have included skeletally anchored protraction of the maxilla for treating Class III malocclusions or the intrusion of teeth in patients with a deep bite. This study was conducted to assess the condition of bone before cortically implanting miniplates in that area of the maxilla.
  
  
  METHODS
  A total of 51 thin-sliced computed tomography scans of 51 fully-dentate adult patients (mean age 24.0 ± 8.1 years; 27 men and 24 women) obtained prior to third-molar osteotomy were evaluated. Study parameters included total bone thickness, thickness of the facial cortical plate, and width of the nasal maxillary buttress. All these parameters were measured at different vertical levels.
  
  
  RESULTS
  The bone volume adjacent to the piriform aperture was most pronounced at the basal level and decreased progressively toward more cranial levels. The basal bone structure had a mean total thickness of 7.8 mm, facial cortical plate thickness of 1.9 mm, and nasal maxillary buttress width of 9.2 mm. At 16 mm cranial to the aperture base, these values fell to 5.6 mm, 1.3 mm, and 5.8 mm, respectively.
  
  
  CONCLUSIONS
  These bone measurements suggest that screws 7 mm in length can be inserted at the base level of the piriform aperture and screws 5 mm long at the cranial end of the bone.
authors.affiliation: Department of Orthodontics, Dentofacial Orthopedics and Pedodontics, Charité - University Medicine Berlin, Assmannshauser Str. 4-6, 14197, Berlin, Germany, thomas-michael.praeger@charite.de.
authors.forename: T M
authors.initials: TM
authors.lastname: Präger
authors.forename: H G
authors.initials: HG
authors.lastname: Brochhagen
authors.forename: R
authors.initials: R
authors.lastname: Mischkowski
authors.forename: P-G
authors.initials: PG
authors.lastname: Jost-Brinkmann
authors.forename: R
authors.initials: R
authors.lastname: Müller-Hartwich
mesh_terms: D000328:Adult; D001860:Bone Plates; D001863:Bone Screws; D003757:Dental Implantation / Q000379:methods*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D008313:Malocclusion, Angle Class III / Q000000981:diagnostic imaging* / Q000628:therapy*; D008437:Maxilla / Q000000981:diagnostic imaging* / Q000601:surgery; D008875:Middle Aged; D008904:Miniaturization; D009929:Organ Size; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation* / Q000379:methods; D011859:Radiography; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D053441:Suture Anchors; D055815:Young Adult