Sudden and unbearable pain in the tooth should be a symptom of acute pulpitis. Pulpitis is an inflammatory lesion that occurs in the pulp tissue, which is a loose connective tissue containing mainly nerve vessels and located in the pulp chamber inside the tooth. Deep caries, wedge-shaped defects and other dental hard tissue diseases can cause pulpitis if not controlled and treated effectively in a timely manner, making it one of the most frequent and common diseases in the oral cavity. The main cause of pulp inflammation is infection, when the hard tissues of the teeth are damaged for various reasons, bacteria can invade and infect the pulp, among which caries is the most common disease that causes the loss of hard tissues of the teeth. Clinical manifestation, the main symptom of acute pulpitis is severe pain, which has typical clinical characteristics of sudden occurrence of severe pain without any external stimulation, and the pain has the process of persistence and relief, so it has the characteristics of paroxysmal attack and paroxysmal aggravation. Secondly, there is nocturnal pain, and patients often have difficulty sleeping because of toothache. Temperature stimulation can intensify the pain, which can be provoked or intensified when eating hot or cold foods, and often patients are afraid to brush their teeth with cool water. The advanced stage of pulpitis is also characterized by hot pain and cold relief, and hot stimulation can produce severe pain. This is often done by rinsing with cool water to temporarily relieve the pain. During painful episodes, most patients are unable to clearly identify the location of the affected tooth, and the pain often radiates to the upper and lower jaw teeth and head and face on the same side of the affected tooth.