Is linear distance measured by panoramic radiography reliable?

Objectives To re-examine the reliability of distance measurements on clinical panoramic radiographs by comparing them with computed tomography (CT) images, from which the most accurate distance measurement is possible . Methods Twenty pairs of images from patients examined both with panoramic radiography and CT for dental implant treatment planning in the premolar and molar regions of the mandible were used. The vertical linear distance between the alveolar crest and the closest mandibular canal was measured by three experienced oral radiologists on both images. The distances measured on panoramic radiographs were corrected for the magnification factor at the focal plane. Double-oblique cross-sectional images were used for CT. Pearson’s correlation coefficient was calculated between distances obtained from both images. The paired t test was performed for statistical comparison. Error levels with the panoramic radiograph versus the CT image were also calculated. Results Pearson’s correlation coefficient showed a significant strong linear correlation ( R = 0.90; p