Examine the mixed-dentition panoramic radiograph. In the region of the permanent first molar, a tooth is present in the arch with primary-molar crown morphology while a fully formed permanent tooth lies unerupted beneath it. What is the correct interpretation?

Correct answer: A. An impacted permanent first molar with the primary second molar retained above it

• A. CORRECT. The interpretive key is CROWN MORPHOLOGY, not simply counting teeth. The tooth visible in the arch has the bulbous crown and divergent roots of a PRIMARY molar; the fully formed tooth trapped beneath it is the PERMANENT FIRST MOLAR, impacted. Impaction of a permanent first molar is uncommon but well recognised, arising from ectopic eruption, an arch-length deficiency or a physical obstruction, and it warrants prompt referral because the tooth is a critical occlusal keystone.
• B. Dilaceration is an abrupt bend in the root or crown of a single tooth. The tooth here is normally formed and simply fails to erupt.
• C. The supernumerary trap is precisely what this image is designed to catch. A rapid count suggests an extra tooth, but a supernumerary would show ATYPICAL morphology — conical, tuberculate or diminutive. Here both teeth have normal morphology for their own series.
• D. The tooth in question is in the MOLAR region; a retained primary canine sits in the canine region and has a single tapered root.

Note: ⚑ The contributor labelled this 'ojo de águila' — eagle eye. On any mixed-dentition panoramic, read the CROWNS before you count: primary molars are bulbous with a marked cervical constriction and widely divergent roots; permanent molars have a larger, less constricted crown. Ignore the incidental impacted upper anterior in this comparison film — it was not part of the exam item.