Tooth decay in children can be divided into many kinds of cases. If it is only a case of anterior caries or intermediate caries, it is not necessary to do root canal treatment, and it is possible to do filling treatment directly. If pulpitis or periapical lesions occur during deep caries in children, root canal treatment is needed. However, if the inflammation of the periapical area of children’s decayed teeth is very large, and the inflammation of the periapical area can not be completely recovered through root canal treatment, or the inflammation of the periapical area can not be controlled, and the root of children’s milk teeth resorbs a large portion of the teeth, the milk teeth will need to be extracted, and the gap keeper will be needed to hold the gap after the milk teeth have been extracted. The gap is also held up by a gap retainer after extraction. Therefore, tooth decay in children should be treated in different situations, not every kind of tooth decay needs root canal treatment, and root canal treatment will not cause damage to the permanent teeth, and the following permanent teeth can still erupt normally.