Recurrent episodes of neuritis, i.e. pulpitis, may be due to the persistence of pathogenic factors, commonly microbiologic factors, physical and chemical factors and immunologic factors. 1. Microbial factors: the main pathogenic factors. When the integrity of tooth enamel or dentin is damaged due to deep caries, trauma, etc., it can be infected through the exposed dentin tubules or blood-borne pathways to cause pulpitis. 2. Physical factors: including acute and chronic trauma caused by damage to the apical blood vessels, excessive temperature stimulation, adjacent teeth of dissimilar metal restorations, etc. resulting in damage to the pulp. 3. Chemical factors: filling and restorative materials, acid etching agents, etc. have a certain degree of irritation, which can cause the occurrence of pulpitis. 4. Immune factors: antigenic substances in the dental pulp can induce immune reaction and cause damage to the pulp. If there is any discomfort, it is recommended to consult a doctor in time for diagnosis and treatment.