Vertical root fracture — classic "J-shaped" radiolucency enveloping the root.

A vertical root fracture often follows endodontic treatment and post placement. Hallmarks: isolated narrow deep pocket, sinus tract often near the mid-root, and a "J-shaped" or halo radiolucency that wraps from the apex along the lateral root surface. Definitive diagnosis often requires surgical flap exposure or CBCT. Prognosis is poor — extraction is usually indicated.