The anesthetic strength usually wears off in 2 to 4 hours after tooth extraction. Commonly used anesthetics for tooth extraction are lidocaine and ativan. Lidocaine is mostly used for nerve block anesthesia, and the maintenance time of anesthesia is around 2 hours. Articaine is mostly used for local infiltration anesthesia, and the numbing time is around 4 hours. If adrenaline is added to the anesthetic it will double the duration of the anesthetic. If the tooth has chronic inflammation such as red, swollen and pus-filled gums, or if the patient is mentally stressed and under the influence of alcohol, the absorption of anesthesia will be affected and the effect will be poorer. Therefore, the anesthetic strength after tooth extraction usually disappears after 2~4 hours, during this period try to avoid eating too hot food, so as not to burn the soft tissue mucosa of the oral cavity.