Refractory apical periodontitis associated with a calculus-like deposit at the root apex

In this case report, we describe a refractory case in which a calculus-like deposit was found at the apical root surfaces of two adjacent teeth. This case involved a 45-year-old male with a sinus tract at the labial mucosa of the maxillary left central incisor, which did not heal after conventional root canal treatment of the maxillary left lateral incisor. Periradicular radiolucencies and unusual radio-opacities were noted on the root surfaces of the vital maxillary left central incisor and prior endodontically treated lateral incisor. Subsequent surgery found calculus-like particles at the root surface of both teeth. A pathology examination revealed calculus-like particles scattered in the granulomatous tissue. A test cavity confirmed pulp necrosis of the maxillary central incisor, and endodontic treatment was performed 1 year after surgery. At the 20-month recall, the size of the periapical radiolucency had decreased. The presence of calculus-like particles at the root surfaces was noted and may have possibly contributed towards the etiology of root canal treatment failure.