title: Precise screw positioning at the mandibular angle: computer assisted versus template coded.
abstract: BACKGROUND
  Buried intraoral devices for distraction osteogenesis in mandibular deformities have numerous advantages, but success depends on the precise positioning of these devices. Although most centers nowadays use template-guided techniques for precise positioning, computer navigation has been described as a promising technique. Surgical navigation during device placement could become a viable method because it affords certainty in defining a device position.
  
  
  METHODS
  A clinical situation was simulated by means of mounting a mandible model inside a phantom head. Screws were positioned according to a preoperative plan through transoral and transbuccal approaches, with both template-coded and freehand computer navigation.
  
  
  RESULTS
  With template-coded navigation, the medium deviation from the planned position was 0.63 mm (range, 0.00-1.24 mm). With commercial freehand surgical computer navigation, the medium deviation was significantly higher at 0.98 mm (range, 0.00-3.13 mm).
  
  
  CONCLUSIONS
  Computer-assisted surgery can provide a high level of accuracy in the region of the mandibular angle where precision is crucial for buried intraoral distraction devices. However, template-coded guidance does provide a significantly higher level of accuracy and therefore represents the gold standard.
authors.affiliation: Clinic for Cranio-Maxillofacial and Oral Surgery, University Hospital of Zurich, Zürich, Switzerland. t.luebbers@gmail.com
authors.forename: Heinz-Theo
authors.initials: HT
authors.lastname: Lübbers
authors.forename: Astrid
authors.initials: A
authors.lastname: Kruse
authors.forename: Peter
authors.initials: P
authors.lastname: Messmer
authors.forename: Klaus Wilhelm
authors.initials: KW
authors.lastname: Grätz
authors.forename: Joachim Anton
authors.initials: JA
authors.lastname: Obwegeser
authors.forename: Felix
authors.initials: F
authors.lastname: Matthews
mesh_terms: D001863:Bone Screws; D006801:Humans; D008334:Mandible / Q000601:surgery*; D008953:Models, Anatomic; D019857:Osteogenesis, Distraction / Q000295:instrumentation*; D025321:Surgery, Computer-Assisted / Q000379:methods*