If the tooth is cracked after root canal treatment, it is necessary to choose different ways of filling and extraction according to the degree of cracking for symptomatic treatment. 1. If only the crown is cracked and the cracked area is small, the crown of the cracked part can be removed, and according to the condition of the remaining crowns, filling materials can be applied to fill in the treatment for the time being, and the adult patients can also choose porcelain crowns for repairing, in order to restore the shape and function, and to prevent the tooth from cracking or falling off. 2. If the degree of cleavage is large and has reached the subgingival level or even the root of the tooth is cracked, the root canal treated tooth will need to be extracted. After the alveolar bone is stabilized, a denture will be used to restore the tooth’s function; 3. If one of the roots of a multi-rooted tooth is split, a hemisection can be considered, i.e., removing the diseased portion of the tooth and restoring the other half for restorative treatment. Due to the lack of nutrient supply from the pulp, the tooth becomes fragile after root canal treatment and is prone to splintering when encountering greater chewing force. Avoid eating too hard food and seek medical attention if you experience pain.