Three and a half year old baby toothache, you can carry out oral examination, shooting whole mouth surface tomography respectively treatment, specific treatment is as follows: 1, remove stagnant food: if the adjacent relationship of the milk teeth is poor, often embedded food debris, you can eat less coarse fiber food, brush your teeth in time after the meal, the application of flossing, rinsing, etc. to remove the stagnant food, to alleviate the stimulation of the gingival papillae. 2, filling: if the milk teeth to form a deeper caries, pain when cold and hot stimulation. If there is pain in cold or hot stimulation, you can scrape off large pieces of decayed material, prepare cavity shape and fill it with glass ionomer cementum, etc. 3.Repair: If pulpitis or apical periapical inflammation occurs in milk teeth, you can grind open the pulp cavity under local anesthesia, remove the pulp, and then use 3% hydrogen peroxide solution to rinse the root canal, close the canal cavity and then use silver amalgam to repair the defects, etc. 4.Wear a gap keeper: When the milk teeth form residual roots and crowns, and are infected, causing swelling and pain, you can use flossing to remove trapped food to reduce the stimulation of the gingival papillae. When infection, swelling and pain are caused, the gap retainer can be worn after extraction.