When caries appears in three-year-old baby, clinically it can be divided into shallow caries, medium caries and deep caries according to the depth of destruction, which needs to be treated by doctor as soon as possible and cannot be treated at home by oneself. 1.Shallow caries and medium caries: usually use special chemical or dental drill to remove the decayed tissue of the tooth, clean and disinfect the cavity, then choose suitable material to fill it to prevent the caries from continuing to aggravate; 2.Deep caries: the caries is close to the pulp, which needs to remove The carious tissue, do the appeasement treatment or root canal treatment according to the situation. After the root canal treatment, you can choose the preformed crown or fill the tooth with special material to repair the tooth. If the root of the affected tooth has been exposed or only the residual root is left, extraction should be done and a gap retainer needs to be made after the extraction of the back tooth. Parents should pay attention to their baby’s oral hygiene in general, teach them to brush their teeth correctly and develop good oral habits. Take your baby for regular dental check-ups, preferably once every six months to check the oral condition.