Effect of axial plane deviation on cross-sectional height in reformatted computed tomography of the mandible.
OBJECTIVE
To assess the effect of angular deviation on the measured height of the mandible in reformatted cross-sectional CT scans.


METHODS
Reformatted cross-sectional CT scans were obtained from three dried mandibles, at three angulations, in a special holding and positioning device for perpendicular measurements. The radiographic lengths of 321 measurements were compared with the actual bone length.


RESULTS
The mean difference between actual bone length and image length, with transaxial planes parallel to the lower border, was 0% (s.d. 3.6). Deviations of 10 degrees and 20 degrees from the lower border of the mandible resulted in a mean error of 1% (s.d. 4.5) and 2.8% (s.d. 8.0) respectively. When the angulation between the deviated transaxial plane and the lower border was greater than 10 degrees, the maximum error was about +/- 30%.


CONCLUSIONS
The use of different transaxial planes along the mandible may result, in a small proportion of cases, in discrepancies in height when measured from the cross-sectional images obtained. This may lead to incorrect interpretation of the depth of bone available for implants.
Kohavi
D
D
Department of Prosthodontics, Hebrew University-Hadassah School of Dental Medicine, Jerusalem, Israel.
Bar-Ziv
J
J
Marmary
Y
Y
D003758:Dental Implantation, Endosseous; D003951:Diagnostic Errors; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008334:Mandible / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed