Some people are reluctant to get a filling because they have experienced pain in their teeth after having a filling. After going to the hospital for treatment of a dental problem, sometimes toothache occurs again, probably in the following cases. If you understand the reasons, you will know the countermeasures, and you do not need to avoid seeking treatment because you are worried about the pain after filling. 1.Deactivation of the pulp (commonly known as nerve killing) is required for treatment, and toothache may occur on the day or the next day after sealing the inactivation drug because of the effect of the drug, but the pain will not be very intense and will not last for a long time. 2.The pain of hot and cold irritation may appear for a short time because of the process of preparing the cavity or the stimulation of the pulp by the disinfection medicine. 3.The cavity is deeper and the cushion material used is too thin to isolate the cold and hot stimulation conducted by the silver amalgam, and the symptoms of cold and hot stimulation pain will appear. It is necessary to thicken the cushion material and then make filling. The cause of irritation pain or spontaneous pain after filling in the near future may be caused by some chemicals in the filling material that irritate the pulp or apical tissue, or may be caused by incomplete pulp inactivation. The cause of pain in the distant future is often secondary caries complicated by pulpitis, and pulp appeasement should be performed depending on the case. When the caries of the tooth has not yet reached the pulp tissue, but has approached the pulp cavity, and when removing the decayed tissue, the affected tooth is extremely sensitive, sometimes accompanied by mild pain; or in daily life, only when encountering cold, hot, sour, sweet and other stimuli, the tooth appears pain. “Soothing treatment” means treatment that is done to relieve and eliminate these symptoms without damaging the pulp tissue. If there is a recent painful bite, most likely the filling material is too high and the bite is caused by early contact. It can return to normal after a few days of conditioning. In conclusion, except for the temporary toothache (such as pulp inactivation) that the doctor clearly tells the patient may occur, all other cases of toothache that occur after filling should be seen in the hospital so that the cause can be identified and treated in time.