Mental Foramen Mimicking Pathology — ORE Part 1 MCQ

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EasyRadiology & ImagingMental Foramen Mimicking PathologyORE Part 1

A 35-year-old patient has no pain, swelling or tenderness to percussion. A periapical radiograph shows a well-defined radiolucency close to the apex of the lower right second premolar. The tooth has a large amalgam restoration but gives normal responses to cold testing and EPT. What is the most likely diagnosis?

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Correct answer: A — Mental foramen

The radiolucency is most likely the mental foramen. This normal anatomical landmark is commonly projected close to the mandibular second-premolar apex on periapical radiographs, so it can simulate apical disease. The normal cold and EPT responses, together with absence of symptoms and percussion tenderness, make an endodontic periapical lesion unlikely. A periapical granuloma, radicular cyst and periapical abscess are consequences of pulpal infection and would not fit a normally responsive, asymptomatic tooth. A lateral periodontal cyst may occur adjacent to a vital tooth, but it is an uncommon developmental lesion on the lateral root surface and does not explain the characteristic second-premolar apical projection as well as the mental foramen.

Reference: Phillips JL, Weller RN, Kulild JC. The mental foramen: 2. Radiographic position in relation to the mandibular second premolar. Journal of Endodontics. 1992. https://pubmed.ncbi.nlm.nih.gov/17209776/