Nicolau Syndrome with Severe Facial Ischemic Necrosis after Endodontic Treatment: A Case Report.

Nicolau syndrome (NS) is a rare complication resulting from intramuscular injections. It is characterized by severe pain at the injection site and the development of purplish discoloration. Only a limited number of case reports have been published documenting the adverse effects associated with the injection of calcium hydroxide (CH) beyond the apex during endodontic treatment. Here, we present the case of a 16-year-old female with NS after the injection of CH during the root canal treatment. The radiography examination revealed distal occlusion of the right maxillary and facial arteries. This caused a substantial area of skin necrosis to develop on the patient's face, resulting in permanent scarring. NS is associated with the displacement of CH beyond the apex. To minimize the risk of NS, dentists should exercise caution by avoiding forced injection of CH during treatment, particularly when the root canal is actively bleeding.