Cephalometric evaluation of posteroanterior projection of reconstructed three-dimensional Cone beam computed tomography, two-dimensional conventional radiography, and direct measurements

• PA image from 2D conventional radiograph is comparable with PA image derived from 3D CBCT.
• PA image from 2D conventional radiograph is also comparable with direct measurements.
• PA image from 2D conventional radiograph is reliable for use in frontal cephalometric analysis.
• The majority of the frontal cephalometric measurements are clinically significant within 0.5 mm.

IntroductionThe purpose of this study is to assess the reliability of 2D postero-anterior (PA) projection derived from 3D Cone Beam Computed Tomography (3D) in comparison with conventional 2D PA cephalometric radiographs as well as to direct measurements.Material and MethodsFull head CBCT and 2D Postero-Anterior (PA) Cephalograms were obtained on 23 dry skulls with intact skeletal structures. Subsequently, another set of 2D PA cephalometric radiographs were generated from the CBCT images. Landmarks have been identified for each postero-anterior projection. Linear measurements (15 horizontal and 3 vertical) derived from Ricketts frontal cephalometric analysis were compared for the 2D radiographs, 3D CBCT, and direct measurements.ResultsOnly one cephalometric measurement (ZAR-ZAL) indicated clinically and statistically significant mean difference when comparing 2D vs 3D and 3D vs direct measurements.ConclusionThe study found linear postero-anterior cephalometric measurements of 2D conventional cephalometric radiographs (2D) to be reliable when compared to CBCT derived images (3D) and direct measurements.