Figure 1 Initial and final radiographs taken by the referring dentist: A Radiograph; c) Final radiograph with temporary restoration.

Radiological and clinical evaluations indicated pulp necrosis along with chronic apical periodontitis. The patient reported painful sensitivity to touch and percussion, as well as spontaneous pain. Given the discharge from both sides of the teeth, vertical root fracture (VRF) and bilateral maxillary sinus tracts were considered in the differential diagnosis, with differing prognoses for each condition. Sinus tract tracing was not possible, as the tract had closed due to the patient’s prior antibiotic use, which began two weeks before her evaluation. These antibiotics had been prescribed by the referring dentist following initial Root Canal Therapy (RCT) (Figure 1C). However, probing depth assessment revealed no J-shaped lesion, making VRF less likely. Due to this and the patient’s financial limitations, CT imaging was not pursued.

The patient underwent a single-visit root canal retreatment as the first-line approach for a potentially savable tooth. The procedure began with the administration of local anesthesia using 2% lidocaine and epinephrine 1:100,000 (Daroupakhsh, Tehran, Iran). The temporary restoration was carefully removed using a high-speed diamond round bur number 2 (Jota AG, Rüthi, Switzerland) and a continuous water spray. The entire process was performed under rubber dam isolation and with a dental operating microscope (Zumax Medical Co., Suzhou New District, China) to ensure precision and safety. To prepare the root canals, gutta-percha was removed with chloroform (Morvabon, Tehran, Iran), gates glidden drills (number 1, 2, 3), and M3 retreatment rotary files (UDG, Changzhou, China). The working length of the canals was determined using an electronic apex locator (Dempex, DEM Ltd., England) and verified through radiography (Figure 2A). Root canals were prepared using a crown-down technique with M3 rotary files (UDG, Changzhou, China) up to size 25 .04, except for the MB2 canal, which was shaped to a smaller size (size 20 .04). The MB2 canal was found and classified as type 2, merging with MB1 in its coronal part. Extensive irrigation and passive ultrasonic activation of sodium hypochlorite and normal saline alternately were performed during canal instrumentation. After confirming the cone fit through radiography (Figure 2B), the canals were dried using sterile paper points (META, South Korea) and obturated with gutta-percha (META, South Korea) and a bioceramic sealer (NeoSEALER Flo, Avalon Biomed, Houston, TX, USA) using a warm vertical technique with FastFill warm obturator (Fast Fill Obturation System, Eighteeth, china) (Figure 2C) <Figure 2>.