Extraoral imaging: OPG, cephalometric radiography
Oral Medicine and Radiology · Dental (BDS)
Study notes
A student measures root length on an OPG. Why is this unreliable? Panoramic magnification (1.2-1.3x) varies by position and the image layer is thick - fine measurements need IOPA/CBCT. Students learn modality honesty: OPG surveys (impactions, asymmetry, gross pathology), cephalometrics standardize (reproducible orthodontic measurements), neither replaces intraoral detail - the right image for the question.
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