Radiology · single question
On a lateral cephalometric radiograph, what does the antero-posterior (AP) measurement assess?
Show answer and explanation
Correct answer: B. Sagittal (antero-posterior) skeletal jaw relationship (Class I/II/III)
Antero-posterior cephalometric measurements (ANB angle, Wits appraisal, A-P line, nasion perpendicular) assess the sagittal skeletal jaw relationship — whether the patient has a Class I, II, or III skeletal pattern. ANB is the most commonly used AP measurement on dental board exams.
- A. ❌ Mandibular plane angle is a VERTICAL measurement — not AP.
- B. ✅ AP measurements assess the sagittal skeletal jaw relationship (Class I: ANB 0–4°, Class II: ANB >4°, Class III: ANB <0°).
- C. ❌ Incisor inclination is assessed by separate angular measurements (U1 to NA, L1 to NB), not the AP measurement.
- D. ❌ Soft tissue lip position is assessed by the E-line and H-angle — separate from AP jaw measurements.