title: Accuracy of bone surface size and cortical layer thickness measurements using cone beam computerized tomography.
abstract: OBJECTIVE
  The purpose of this study was to determine the accuracy of Cone Beam Computerized Tomography (CBCT) reconstructions in displaying bone surface size and cortical layer thickness.
  
  
  METHODS
  Two fresh frozen cadaver heads were scanned using a CBCT (i-CAT(™) 3D Imaging System; Imaging Sciences International Inc.). The mandibles were sectioned and digitalized for histological evaluation. Dimensions as measured on these sections were compared with CBCT measurements of the same region with the use of 3D image-based planning software (Procera System NobelGuide(™); Nobel Biocare). To allow optimal comparison between histological and CBCT sections, reference markers were placed into the mandibles. The Student t-test was utilized to analyze the data. Differences with P-values <0.05 were considered significant.
  
  
  RESULTS
  The total height and width of the mandibular body, as measured on CBCT views, were larger compared with the histological values with a maximum difference of 0.33 mm (SD ± 0.34). Cortical thickness measurements were significantly thicker on CBCT sections (P < 0.006) with absolute differences ranging up to ±0.63 mm (SD ±0.28) and relative differences ranging up to 82.6%.
  
  
  CONCLUSIONS
  CBCT images (i-CAT 3D Imaging System), viewed on the planning software Procera System NobelGuide, tend to overestimate the anatomical truth in assessing both bone height and width; especially cortical thicknesses are depicted thicker than in reality. When using CBCT images for presurgical assessment, one should be aware of this phenomenon of exaggeration of dimensions.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: Nicolaas Lucius
authors.initials: NL
authors.lastname: Gerlach
authors.forename: Gerrit Jacobus
authors.initials: GJ
authors.lastname: Meijer
authors.forename: Wilfred Ary
authors.initials: WA
authors.lastname: Borstlap
authors.forename: Ewald Maria
authors.initials: EM
authors.lastname: Bronkhorst
authors.forename: Stefaan Jozef
authors.initials: SJ
authors.lastname: Bergé
authors.forename: Thomas Jan Jaap
authors.initials: TJ
authors.lastname: Maal
mesh_terms: D019412:Anatomy, Cross-Sectional / Q000706:statistics & numerical data; D002102:Cadaver; D002508:Cephalometry / Q000706:statistics & numerical data; D054893:Cone-Beam Computed Tomography / Q000706:statistics & numerical data*; D003724:Dental Arch / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D057918:Fiducial Markers; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000706:statistics & numerical data*; D021621:Imaging, Three-Dimensional / Q000706:statistics & numerical data; D007575:Jaw, Edentulous / Q000000981:diagnostic imaging / Q000473:pathology; D008334:Mandible / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D012016:Reference Values