Tooth decay is also known as dental caries, 4-year-old children with caries can have fillings or root canal treatment, or can be extracted directly if it is more serious. The occurrence of dental caries is usually related to poor oral environment, infection, decreased immunity, etc., or the child often eats foods containing more sugar and does not pay attention to cleaning, so that the residual sugar is decomposed by bacteria, producing a large amount of lactic acid, which causes damage to the teeth, causing dental caries. If the child’s tooth decay is shallow, the decayed portion can be removed and the missing portion can be completely filled with dental filling material. If the caries is more severe and there is significant toothache as well as symptoms of pulpitis, root canal treatment will be necessary. If the tooth is severely decayed and has no value for retention, it can also be directly extracted to wait for the subsequent eruption of permanent teeth. It is recommended to bring your child to the hospital for examination and standardized treatment according to your child’s specific situation.