The oral cavity is rich in blood flow, which can cause excessive bleeding. Excessive bleeding in oral cavity is rare, but if the cause of the bleeding is not found, the patient's life may be at risk. Therefore, in the case of excessive bleeding, the dentist should consider the cause and provide appropriate first treatment. Hydrofluoric acid is widely used as a material for pre-treatment of ceramics before oral restoration for prosthetics and conservative dentistry. Since hydrofluoric acid is very reactive, when it comes into contact with tissues, even very diluted 0.1% hydrofluoric acid can cause very painful 2-3 degree burns, which heal very slowly. Negative reactions and even deaths of hydrofluoric acid have been reported in other fields, but there are very few case reports of complications related to hydrofluoric acid in the dental field. In this article, we report a case of excessive gingival bleeding after restorative treatment and discuss the effects of hydrofluoric acid on oral soft tissues and blood vessels and its prevention

• 유태민(단국대학교 치과대학 통합치의학 교실) | Tae Min You (Department of Advanced General Dentistry, School of Dentistry, Dankook University) Correspondence