There are several possible reasons for sour teeth: 1.Caries on the teeth, caries will lead to dentin defects, dentin tubules exposed in the mouth, when eating hot, cold, sour and sweet food will induce the symptoms of dentin allergy, causing sour teeth. 2.Cryptic fracture on the tooth surface, if the fracture is deep, has reached the dentin, will also appear the symptoms of dentin allergy, causing sour teeth. 3, suffering from periodontal disease, periodontal disease patients will have varying degrees of alveolar bone resorption, resulting in gingival atrophy, tooth root exposure, when the root is exposed in the mouth, it will cause teeth sore, soft feeling. 4, teeth feel sore may also be caused by excessive wear of the tooth surface, excessive wear will make the hard tissue of the tooth increasingly thin, thus inducing the dentin Allergy, causing sore teeth.