A 4-year-old child with toothache and tooth decay may be caused by caries, pulpitis, apical periodontitis and other diseases, which can be treated with filling therapy, root canal therapy and other treatment methods. 1. caries: for caries caused by 4-year-old children with toothache tooth rot. It is necessary to seek medical attention to remove the rotten tooth tissue and carry out caries filling surgery. 2. Pulpitis: pulpitis can also lead to 4-year-old children with toothache and tooth decay phenomenon is mainly taken to surgical treatment, mainly direct pulp capping, root canal treatment and other surgical methods, but the specific surgical methods should be determined by the actual situation. 3. apical periodontitis: for apical periodontitis caused by 4-year-old children with toothache and tooth rot, parents can take the child to the hospital, take surgical treatment, such as root canal treatment. When 4-year-old children have symptoms of toothache and tooth decay, it is recommended to seek timely medical treatment to avoid affecting the chewing function and permanent teeth replacement. Usually pay more attention to eat less sweets and brush their teeth on time.