Possible causes of toothache include dentin hypersensitivity, caries, pulpitis, apical periodontitis, wisdom tooth pericoronitis, etc., as follows. 1. Dentin hypersensitivity: Exposure of dentin due to gingival recession, wedge-shaped defects, etc. may cause dentin hypersensitivity, resulting in pain when the teeth are subjected to hot, cold or mechanical stimulation. 2. Caries: When deep caries occurs, the cavity is close to the pulp, and cold water or food entering the cavity will cause pain in the affected tooth. 3. Pulpitis, periapical inflammation: when inflammation occurs in the pulp of the affected teeth will appear pain symptoms, in the acute stage of inflammation for spontaneous pain, night pain, in the chronic stage of inflammation is usually a paroxysmal dull pain. If pulpitis is not treated, it may develop into apical periapical inflammation, which will cause occlusal pain. 4. Wisdom tooth pericoronitis: when the wisdom tooth eruption is incomplete, producing blind pockets, poor oral hygiene and the proliferation of pathogenic bacteria and other factors, it may lead to the production of wisdom tooth pericoronitis, the typical symptoms of toothache, difficulty in opening, and so on. There may be other reasons for toothache, so it is recommended to go to the hospital in time to receive regular treatment as soon as possible.