The loss of milk teeth is related to the state of root resorption, which is usually loose for about three months. However, it varies from person to person. During the period of replacement of milk and permanent teeth in children, the roots of milk teeth are compressed and absorbed by the inherited permanent teeth below, and the milk teeth are loosened and fall out in about three months. The loosening of milk teeth during tooth replacement does not last forever, but is sometimes loose and sometimes strong. When the permanent teeth erupt, there is a resting period, when the lower permanent teeth press the root of the milk teeth to absorb the upward eruption, the milk teeth are loose, when the permanent teeth erupt, the degree of looseness of the milk teeth decreases, you can eat more hard food to accelerate the root resorption, the milk teeth can be lost as soon as possible. The loosening of milk teeth is generally about three months time, permanent teeth eruption of milk teeth did not fall out of the need for timely extraction.