Subcutaneous facial emphysema is an uncommon but potentially alarming complication of dental procedures, resulting from the forced introduction of air into soft tissue spaces. This case report describes the occurrence of subcutaneous emphysema secondary to accidental perforation during root canal preparation for post and core restoration of the maxillary right central incisor in a 20-year-old female patient (ASA I). The patient initially presented for prosthodontic rehabilitation following previous endodontic treatment and was diagnosed with a structurally compromised tooth associated with persistent periapical radiolucency.

During post space preparation, an intraoperative radiograph revealed deviation of the canal path, likely due to bur misdirection. Following the use of an air syringe to clear the operative field, rapid onset of intraoral swelling was observed, which progressed within seconds to marked extraoral facial swelling involving the right midface. Clinical findings were consistent with subcutaneous emphysema.

A diagnosis of subcutaneous facial emphysema secondary to accidental perforation and pressurized air insufflation was established. The patient was managed conservatively with immediate cessation of air-driven instruments, close observation, analgesics, and prophylactic antibiotics. No surgical intervention was required. Although the swelling initially extended to the circumorbital region, gradual spontaneous resolution was observed, with complete recovery achieved within five days.

The patient’s recovery was uneventful, with no residual complications at follow-up. This case highlights the importance of early recognition, avoidance of pressurized air in compromised sites, and prompt conservative management to ensure favorable outcomes in such rare but distressing iatrogenic complications.