The main cause of pulpitis is bacterial infection, mostly seen in the common name of worm teeth or carious disease, through the cavity bacteria into the infection of the pulp, and periodontitis patients have deep periodontal pockets, through the infection of bacterial toxins to the apical foramen, and then retrograde infection caused by pulpitis. In addition, non-carious hard tissue diseases, including wedge defect, abrasion, and trauma, cause cracks or fissures on the hard tissues of the teeth, and then cause the route of infection, so the biggest cause is the infection factor. There are also physical stimuli, such as overheating or overcooling stimulation of deep cavities that are also very irritating to the dental pulp. Chemical irritation, such as the action of strong disinfectant drugs, is also more irritating to the pulp and sometimes more likely to cause pulp inflammation. Then there are immunological factors.