Nicolau Syndrome after Endodontic Treatment: A Case Report

Calcium hydroxide has been used successfully in root canal therapy for many years. However, it can cause serious damage if it is inadvertently displaced into surrounding vital structures, resulting in thrombosis if displaced into blood vessels, damaging connective tissue, and causing skin necrosis. These adverse reactions are known as Nicolau syndrome (NS) or embolia cutis medicamentosa. Very few case reports have been published about these adverse effects of injecting calcium hydroxide beyond the apex during root canal therapy. A 16-year-old female patient was referred to the endodontic department of Hamad Dental Center for assessment after treatment by the maxillofacial surgery department for swelling and tissue necrosis that occurred after endodontic treatment in another clinic. When the patient initially attended the maxillofacial surgery department, she presented with swelling on the left side in the region of the maxillary left first permanent molar. On examination, there was a change in the color of the skin of the left cheek in that area along with some reported paralysis of the left side of her lips. Analgesics and antibiotics had already been prescribed at the referring clinic. Two weeks later, the patient developed a necrotic patch of skin on the same area. Subsequent evaluation at the endodontic department of Hamad Dental Center led to a diagnosis of NS. NS is a very rare iatrogenic condition. Displacing calcium hydroxide beyond the apex might increase the chance of NS. Clinicians should avoid overinstrumentation and forced injection of calcium hydroxide to prevent NS.