Once you eat sweet, teeth appear more sensitive sore phenomenon, mainly caused by the following reasons: 1, dentin allergy. Dentin allergy occurs in patients whose enamel is severely worn out and dentin is exposed, at this time, whether it is cold, hot, sour or sweet, it will play a certain stimulating effect on the pulp after eating, resulting in tooth sensitivity. It is the performance of middle caries. Once the caries is not treated by filling as early as possible, the bacteria will gradually invade the tooth body and some irritating symptoms of the pulp will appear. The pain of cold, hot, sour and sweet stimulation is one of the manifestations, and it is necessary to go to dentistry for filling treatment in time. 3.The gum recession and root exposure caused by periodontitis should be removed in time, and the root desensitization treatment should be carried out.