Teeth will be painful when eating cold and also when eating hot. This may be due to the fact that the enamel on the surface of the teeth is worn and the dentin is exposed, and the teeth are more sensitive to cold, hot, sour and sweet stimuli, so there will be toothache when eating cold and also when eating hot. In this case, you can use some desensitizing toothpaste everyday, if the tooth sensitivity is more serious, you should go to hospital for desensitizing treatment. Another reason may be that the tooth decay has been more serious, and the tooth pulp is exposed, so when it encounters stimulation, it will produce toothache. In this case, it is necessary to go to the dental institution for treatment of tooth decay or filling, and root canal treatment is possible. If the tooth pulp is inflamed and the surrounding nerve has been infected, it is also necessary to go to the hospital for root canal treatment to solve the pain caused by pulpitis.