When the tooth enamel is exposed due to decay, trauma, wear and tear, it will lead to soreness when the tooth encounters cold, hot, sour, sweet and other exogenous stimuli. There are several reasons for sour teeth: 1.Dentin allergy, due to wear and tear of enamel, trauma leading to dentin exposure, it will lead to sore teeth after eating cold, hot, sour and sweet food. 2.After the destruction of dentin layer by tooth decay, it will lead to different degrees of soreness, and further destruction will eventually develop to pulpitis, which will lead to more severe pain. 3.Wedge-shaped defect, due to tooth brushing or biting stress The wedge-shaped defect in the neck of the tooth caused by brushing or biting stress will also cause tooth pain. 4.Cryptoclastic tooth, when there is a hidden crack on the tooth surface, various cold, hot, sour and sweet stimuli will spread to the dentin layer through the crack and cause tooth pain.