Sudden pain in the tooth is usually a typical symptom of acute pulpitis, and it is recommended that the tooth be seen immediately in a hospital for endodontic treatment. Currently, the most effective treatment for pulpitis is endodontic treatment. Through effective root canal treatment, the infected material and inflammation in the pulp cavity and periapical area can be removed, and when the inflammation is eliminated, the affected tooth will no longer hurt. The root canal should be permanently filled to isolate external stimuli and eliminate reinfection. Acute pulpitis is usually caused by tooth decay, and the extent of decay is so large that it has reached the pulp, resulting in inflammation of the pulp tissue and thus causing toothache.