There are certain differences between milk teeth and permanent teeth, which can be identified from several aspects such as the number of teeth, color, time of appearance, and morphology. 1, number: the number of milk teeth is generally 20, and the number of permanent teeth is generally 28-32; 2, color: because the outermost layer of teeth is enamel, the enamel layer of permanent teeth is better mineralized, and the yellow color of tooth essence will come out, while the mineralization of milk teeth is poorer and covers the color of tooth essence. Therefore, milk teeth are generally milky white, permanent teeth are generally yellowish, and the glossiness of permanent teeth is better than milk teeth; 3, emergence time: all milk teeth erupt at the age of about 3 years, and begin to fall out at the age of 5-7 years, and completely fall off at the age of about 12 years. Permanent teeth begin to erupt at the age of 5-7, so teeth that erupt after the age of 5 are usually not milk teeth, and permanent teeth will not be replaced after they have fully erupted; 4. Form: If parents cannot distinguish with the naked eye, they can go to the hospital or dental clinic to take X-rays for accurate identification. The roots of the milk teeth are shorter, the roots of the permanent teeth are longer than the milk teeth, and the crowns of the milk teeth are usually smaller than the inherited permanent teeth, except for the second milk molar.