title: The accuracy of CBCT in measuring jaws bone density.
abstract: BACKGROUND
  The cone-beam computerized tomography (CBCT) has become widely used for oral and maxillofacial imaging, providing a good spatial resolution, gray density range, and contrast, as well as a good pixel/noise ratio. In the CBCT the dimensional accuracy is also comparable with Computer Tomography (CT), but in contrast to the CT, the gray density values of the CBCT images (voxel value [VV]) are not absolute.
  
  
  OBJECTIVE
  The aim of the study was to evaluate if there is a statistically significant difference in bone density values, defined as gray density values (VV), using two different CBCT exposure radiation (8 mAs or 15 mAs).
  
  
  METHODS
  10 dry mandibles were CBCT scanned using two different exposure radiation (8 mAs or 15 mAs). Using software and a radiographic template, the CBCT-scan images were overlapped and two datasets were created, each one giving the respective gray values (VV), of the same area with the same spatial coordinates. The quantified gray density values of the planned volume were measured and expressed as VV in two different exposure radiation scans Groups (Group A: 8 mAs; Group B: 15 mAs). For the statistical analysis, t-test was used.
  
  
  RESULTS
  The differences between the CBCT gray density values (VV) of the Groups (Group A: 8 mAs; Group B: 15 mAs) were statistically significant (p <= .05).
  
  
  CONCLUSIONS
  This study demonstrated that the use of a CBCT to evaluate the bone density of jaws is not useful when the values are taken as absolute values. In spite of the lower radiation dose and costs of CBCT, this new technique does not allow an accurate assessment of bone density.
authors.affiliation: Department of Oral and Maxillofacial Sciences, Sapienza University of Rome, Italy. michele.cassetta@uniroma1.it
authors.forename: M
authors.initials: M
authors.lastname: Cassetta
authors.forename: L V
authors.initials: LV
authors.lastname: Stefanelli
authors.forename: S
authors.initials: S
authors.lastname: Di Carlo
authors.forename: G
authors.initials: G
authors.lastname: Pompa
authors.forename: E
authors.initials: E
authors.lastname: Barbato
mesh_terms: D015519:Bone Density; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D006801:Humans; D007568:Jaw / Q000000981:diagnostic imaging* / Q000502:physiology