The difference between permanent teeth and milk teeth is mainly reflected in the number, color, eruption time, morphology and other aspects. 1. Number: the number of milk teeth is generally 20, and the number of permanent teeth is generally 28 to 32. 2. Color: milky white for milky teeth and yellowish for permanent teeth, and the luster of permanent teeth is better than milky teeth. 3. Eruption time: All milk teeth erupt around the age of 3 and begin to fall out at the age of 5-7, while permanent teeth begin to erupt at the age of 5-7, and they will not be replaced after eruption. 4. Morphology: Generally speaking, the roots of milk teeth are shorter, the roots of permanent teeth are longer than those of milk teeth, and the crowns of milk teeth are usually smaller than those of inherited permanent teeth, with the exception of the second molar. Permanent and milk teeth are generally easy to distinguish from each other, but the first permanent molar that erupts at the beginning of tooth replacement is often mistaken for a milk tooth because it has no counterpart to the milk tooth and there is no corresponding lost milk tooth prior to eruption.