Radicular Cyst — MFDS Part 1 MCQ

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EasyOral PathologyRadicular CystMFDS Part 1

A periapical radiograph of a heavily carious, non-vital tooth shows a round, unilocular, well-defined radiolucency centred on its root apex. What is the most likely provisional diagnosis?

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Correct answer: C — Radicular (periapical) cyst

A radicular cyst is the most likely provisional diagnosis because it is an inflammatory odontogenic cyst characteristically centred at the apex of a non-vital tooth. It develops following pulpal necrosis, with inflammatory stimulation of epithelial rests of Malassez in the periodontal ligament. A dentigerous cyst surrounds the crown of an unerupted tooth. Periapical cemento-osseous dysplasia usually affects vital teeth and often involves multiple mandibular anterior sites. Odontogenic keratocysts and ameloblastomas may be radiolucent but are not characteristically centred on the apex of a non-vital tooth. Radiographic appearances cannot prove that a periapical lesion is cystic rather than a periapical granuloma; definitive diagnosis, where tissue is removed, is histopathological.

Reference: Faculty of Dental Surgery, Royal College of Surgeons of England. Oral Medicine Clinical Syllabus, version 5, section 6.3.1: Odontogenic cysts. 2022. https://www.rcseng.ac.uk/-/media/Files/RCS/FDS/Dental-curricula/Oral-Med-Syllabus-v5_Feb2022.pdf