If the teeth are easily painful when eating sweets, there are mainly the following reasons: 1.Dental caries, dental caries is caused by bacteria causing certain erosion on the surface of the teeth, and cavities appear, at this time once eating sweets, it may stimulate the inner layer of dentin or stimulate the dental nerve, this situation needs to be treated for dental caries. 2.It may be caused by tooth sensitivity, in this case it is due to The tooth enamel on the surface of the tooth is worn or eroded, so that the dentin reacts to the cold, hot, sour and sweet stimulation with sourness and pain. 3. Inflammation such as pulpitis and periodontitis may occur, and the stimulation of sweet food makes the inflammation more serious and causes pain.