The foul odor of blood clot after tooth extraction may be due to the occurrence of dry socket, and the treatment is to isolate the external stimulus after thorough debridement, as follows. 1. After conduction block anesthesia is applied to the extraction area, the alveolar fossa is thoroughly debrided in a painless manner. Cotton balls with 3% hydrogen peroxide solution are repeatedly wiped to remove decayed necrotic material until the cotton balls are clean and odorless alveolar fossa is clean, and a spatula can be used when there are large pieces of decayed necrotic material. 2. Rinse the alveolar socket with saline, then use iodoform gauze to tightly fill in the extraction wound, and suture both sides of the gums to isolate the external stimulation of the alveolar socket. If you have symptoms of dry socket, we recommend that you go to the hospital for early treatment.