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External Resorption Radiograph — MFDS Part 1 MCQ

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ModerateRadiologyExternal Resorption RadiographMFDS Part 1

A periapical radiograph shows a cervical radiolucency associated with a maxillary incisor. Which radiographic appearance most strongly favours external cervical resorption over internal inflammatory root resorption?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: C — An irregular, mottled radiolucency affecting the external root contour, with the root canal outline still traceable

Explanation lettering: C = shown as A · A = shown as C

A is correct. External cervical resorption begins on the external root surface and commonly appears as an irregular, mottled or moth-eaten radiolucency. The root canal wall may remain traceable through or separate from the lesion until late disease. Internal inflammatory resorption instead causes smooth, symmetrical balloon-like enlargement centred on the canal, with loss of its original outline (B). Option C describes cervical burnout, a projectional artefact without true root-surface destruction. Option D is more consistent with apical periodontitis, while isolated periodontal ligament widening (E) is non-specific. External cervical resorption has variable appearances, so periapical radiographs may underestimate its extent and small-field CBCT may be appropriate if the result will affect management.

Reference: Patel S, Saberi N, Pimental T, Teng P-H. Present status and future directions: Root resorption. International Endodontic Journal. 2022;55(Suppl 4):892–921. https://pubmed.ncbi.nlm.nih.gov/35229320/