title: An evaluation of face-bow transfer for the planning of orthognathic surgery.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the error magnitude in the clinical application of face-bow devices. Technical and methodologic inaccuracies, as well as deviations from reference planes, were determined.
  
  
  METHODS
  The presented method is part of a 3-dimensional virtual planning procedure for orthognathic surgery and included 15 patients with dentoskeletal deformities. Cone beam computed tomography datasets obtained from patients with a referenced face-bow plane and a centric registration splint were matched with cone beam computed tomography datasets of the registered plaster model of the maxilla mounted in an articulator. To assess potential sources of methodologic errors, angulations were measured between the virtual face-bow plane and the horizontal cross bar of the virtual articulator. To evaluate the reproducibility of the anatomic reference plane, angulations between the Frankfort plane and the horizontal cross bar of the articulator were measured. Statistical significance was set at P < .05 and tested by univariate analysis of variance.
  
  
  RESULTS
  Technical and methodologic errors showed a mean deviation of 3.5°, with a median of 3.6° and SD of 2.7°. The values did not reach statistical significance (P = .1). However, there was a significant error (P < .05) in determining the position of the anatomic reference plane by face-bow transfer. The mean deviation was 7.7° (values ranged between 1.2° and 18.9°), with a median of 6.7° and SD of 5.3°.
  
  
  CONCLUSIONS
  In this study the traditional use of face-bow devices showed inaccuracies in model mounting as well as in assignment of anatomic reference planes. Three-dimensional virtual computer-assisted planning seems to be more accurate than conventional methods.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Hannover Medical University, Hannover, Germany. c.zizelmann@gmx.de
authors.forename: Christoph
authors.initials: C
authors.lastname: Zizelmann
authors.forename: Beat
authors.initials: B
authors.lastname: Hammer
authors.forename: Nils-Claudius
authors.initials: NC
authors.lastname: Gellrich
authors.forename: Rainer
authors.initials: R
authors.lastname: Schwestka-Polly
authors.forename: Majeed
authors.initials: M
authors.lastname: Rana
authors.forename: Peter
authors.initials: P
authors.lastname: Bucher
mesh_terms: D059925:Anatomic Landmarks / Q000473:pathology; D054893:Cone-Beam Computed Tomography / Q000706:statistics & numerical data; D019465:Craniofacial Abnormalities / Q000473:pathology / Q000601:surgery; D003725:Dental Articulators / Q000706:statistics & numerical data; D003768:Dental Occlusion, Centric; D057918:Fiducial Markers; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000706:statistics & numerical data; D021621:Imaging, Three-Dimensional / Q000706:statistics & numerical data; D007574:Jaw Relation Record / Q000295:instrumentation / Q000379:methods*; D008437:Maxilla / Q000473:pathology; D003765:Models, Dental; D056948:Orthognathic Surgical Procedures / Q000706:statistics & numerical data*; D010347:Patient Care Planning / Q000706:statistics & numerical data*; D012016:Reference Values; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012984:Software; D025321:Surgery, Computer-Assisted / Q000706:statistics & numerical data*; D014584:User-Computer Interface