The cause of toothache is usually due to pulpitis and apical infection. Causes of pulpitis: i. Bacterial factors. 1, due to infection of the teeth, including caries, wedge-shaped defects, severe abrasion, cryptic cracks, etc. 2, periodontal infections. 3, infections of blood origin. Second, physical factors, including acute trauma, chronic occlusal trauma, temperature stimulation, and current action. Third, chemical factors, mainly from the sterilization drugs in the cavity, filling of the filling. Causes of apical inflammation: First, the development of pulpitis to the advanced stage, the pulp tissue or all of the necrosis after the pain. Second, the tooth is hit by violent external force. Medical infection during treatment.