The causes of pain after caries filling are mainly divided into pulpal pain and periodontal pain: 1. Pulpal pain: it is manifested as excitation pain, and external cold, hot, sour and sweet stimulation can cause pain. The common reason is the physical stimulation to the pulp during the grinding process; the cavity is deeper when the resin filling is carried out, there is no cushion or the cushion material is not selected properly, or the operation is not proper. Pulpal pain is also manifested as pain when contacting with the opposing teeth, this is usually the case for teeth filled with silver amalgam, the opposing teeth are usually metal material, when the upper and lower teeth are in contact, electric current is generated, thus causing pain; the third manifestation of pulpal pain is mainly spontaneous pain, it can be manifested as paroxysmal pain, not sure which tooth, hot and cold temperature stimulation can also induce or aggravate the pain, this situation is generally considered to have This condition is generally considered to have the possibility of pulpitis. The reason of recent emergence is mainly because of the wrong diagnosis, chronic pulpitis is diagnosed as caries; the reason of distant emergence is one is the chronic stimulation of filling material to the pulp, and then there is a secondary caries or more caries tissue left at the bottom of the cavity, the lesion continues to develop and involves the pulp; 2, periodontal pain: the first one is occlusal pain, the occlusal pain is generally too high filling material; the second one is spontaneous pain. This pain is usually persistent, can be localized, has no relationship with temperature stimulation, and can be aggravated when chewing. The reason is usually the poor recovery of the contact point of the filling material, which causes food embedding and gum inflammation; the second is the formation of overhang of the filling material near the gum, which leads to plaque accumulation and pressure on the gum, which can also cause gum inflammation; and then the operation process damages the gum and even the periodontal membrane.