Tooth pain in three-year-old babies, in most cases, is due to caries produced by the child’s milk teeth, which needs to be treated in a professional oral health care institution, preferably one with children’s dentistry. First, the depth of caries should be checked, and then the high-speed turbo drill of dentistry should be applied to remove the caries cleanly, and the caries should be repaired by applying a special filling material. If the caries has not reached the pulp, the treatment is completed. If the caries has already invaded the pulp of the milk tooth, further root canal treatment of the milk tooth is required to remove the top of the pulp chamber of the milk tooth, extract the pulp of the milk tooth, and then finish the treatment of the milk tooth by applying the root canal treatment of the milk tooth.