Sodium hypochlorite accident in mandibular premolar associated with a sinus tract

Abstract Sodium hypochlorite (NaOCl) is a widely used endodontic irrigant; however, accidental extrusion beyond the apical foramen can result in severe soft tissue injury. This report describes a NaOCl accident in a 32-year-old medically fit male who was referred for completion of root canal treatment of the right mandibular first premolar associated with a chronic sinus tract. The patient’s chief concern was a persistent sinus tract and discharge despite previous treatment. Clinical examination and tracing of the sinus tract through a periapical radiograph confirmed a chronic apical abscess in a tooth with previously initiated therapy. During irrigation with 5.25% NaOCl through a side-vented needle under rubber dam isolation, the patient experienced immediate pain and bleeding, consistent with NaOCl extrusion. A cone beam computed tomography scan confirmed intact root anatomy with no apical perforation. Prompt management included cessation of NaOCl irrigation, copious saline irrigation, incision and drainage, calcium hydroxide placement, and close follow-up. Subsequent visits demonstrated complete healing of the sinus tract, and the tooth was obturated and restored. Six-year follow-up showed a functional, asymptomatic tooth with radiographic evidence of complete periapical healing. This case emphasizes the importance of early recognition, appropriate management, and preventive strategies for NaOCl accidents, particularly in teeth with sinus tracts and complex anatomy.