title: Reproducibility of 3 different tracing methods based on cone beam computed tomography in determining the anatomical position of the mandibular canal.
abstract: OBJECTIVE
  To investigate the reproducibility of 3 different tracing methods to determine a reliable method to define the proper anatomical position of the mandibular canal based on cone beam computed tomography (CBCT) data.
  
  
  METHODS
  Five dentate and 5 edentate patients were selected at random from the CBCT database. Two independent observers traced both the left and the right mandibular canal using 3-dimensional image-based planning software (Procera System NobelGuide; Nobel Biocare, Göteborg, Sweden). All mandibular canals were traced using 3 different methods. Method I was based on coronal views, also known as cross-sections. Panorama-like reconstructions were the starting point for method II. The third method combined methods I and II.
  
  
  RESULTS
  With respect to interobserver reliability, no significant difference (P = .34) for the various methods was observed. The reproducibility was better in edentate than in dentate jaws (P = .0015). The difference between 2 tracings was the lowest for the combined method: within a range of 1.3 mm in 95% of the course of the canal. The most obvious deviations were mainly seen in the anterior part of the canal.
  
  
  CONCLUSIONS
  The best reproducible method for mandibular canal tracing is the combined method III. Between observers, still a mean 95th percentile deviation threshold of 1.3 mm (SD 0.384) is noted, indicating that a safety zone of 1.7 mm should be respected. When planning surgery on CBCT-based data, surgeons should be aware of the obvious deviations located in the region of the anterior loop of the canal.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Radboud University Nijmegen, Medical Centre, Nijmegen, The Netherlands.
authors.forename: Niek L
authors.initials: NL
authors.lastname: Gerlach
authors.forename: Gert J
authors.initials: GJ
authors.lastname: Meijer
authors.forename: Thomas J J
authors.initials: TJ
authors.lastname: Maal
authors.forename: Jan
authors.initials: J
authors.lastname: Mulder
authors.forename: Frits A
authors.initials: FA
authors.lastname: Rangel
authors.forename: Wilfred A
authors.initials: WA
authors.lastname: Borstlap
authors.forename: Stefaan J
authors.initials: SJ
authors.lastname: Bergé
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002508:Cephalometry / Q000379:methods; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007575:Jaw, Edentulous / Q000000981:diagnostic imaging; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging / Q000294:innervation; D008340:Mandibular Nerve / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D008875:Middle Aged; D015588:Observer Variation; D011862:Radiography, Panoramic / Q000379:methods; D011873:Radiology Information Systems; D015203:Reproducibility of Results; D012984:Software; D055815:Young Adult