The eight-year-old tooth is caved in, need to take pictures to check the damage to the tooth, if it can be root canal treatment, first root canal treatment after pile core crown restoration, if can not be retained, need to be extracted. 1. Root canal treatment. Root canal treatment can be carried out if the tooth has not penetrated through the pulp chamber and if the tooth has value for preservation, followed by crown restoration. 2. Extraction. If the tooth is decayed and most of the tooth tissue is missing, the internal pulp cavity is decayed to the bottom of the pulp chamber, and the inflammation of the tooth is so severe that the tooth cannot be preserved through root canal treatment, the tooth needs to be extracted and then prosthetic restoration is carried out. Eight-year-old tooth decayed empty, it is recommended to promptly go to the hospital to check the specific degree of tooth decay, according to the situation targeted treatment.