On a periapical radiograph, a dark line following the external surface of the root in a J-shape is most consistent with:

Correct answer: C. Vertical root fracture

• A. Hypercementosis appears as increased radio-opacity (not radiolucency) at the root apex due to excessive cementum deposition.
• B. A periapical cyst or PA lesion is typically round/oval at the apex — not a J-shape along the lateral root.
• C. Correct. A J-shaped or halo-shaped radiolucency along the lateral and apical surface of the root is the classic radiographic presentation of a vertical root fracture. The fracture allows bacteria to enter, creating lateral bone loss in a J or halo pattern.
• D. External resorption appears as irregular shortening of the root — not a J-shaped radiolucency along the root.