The most common cause of long milk tooth roots is ectopic eruption of permanent teeth and non-resorption of milk tooth roots. When children’s teeth are replaced, the permanent teeth erupt and the milk teeth are lost. If in the process of eruption, the permanent teeth deviate from the normal eruption path, or during the replacement of teeth, the milk teeth do not get enough chewing stimulation, there will be the phenomenon of milk teeth roots are not absorbed, the milk teeth roots will be very long, and the teeth can not fall off by themselves, and they need to be extracted in time. Therefore, during the period of children’s teeth replacement more chewing hard things, such as apples corn, etc., to accelerate the absorption of the roots of the milk teeth. If the permanent teeth have already erupted and the milk teeth have not fallen out, they need to be extracted in time to avoid situations such as uneven teeth.