A 13-year-old has retained deciduous teeth and unerupted mandibular first premolars. Which radiograph best determines the cause of non-eruption (3-D localization)?

Correct answer: B. Cone-beam computed tomography (CBCT)

• A. A PA gives only a 2-D view, insufficient for full 3-D localization of impactions/obstructions.
• B. Correct. CBCT provides 3-D imaging to localize the unerupted teeth and identify obstructions (e.g., supernumeraries, odontomas).
• C. MRI is poor for mineralized dental hard tissue and not the imaging of choice for eruption assessment.