This is a case where, based on the X ray image of a “J” type lesion, and on a deep narrow periodontal probing, one could easily think of a cracked tooth. The microscope showed us otherwise. No crack could be found under microscope observation. As shown on those VRFs, slow but complete periradicular tissues regeneration followed root canal retreatment (which implied a few calcium hydroxyde dressings replacements). This J shaped radiolucency was in fact a narrow desmodontal sinus tract.