Tooth loss usually refers to the natural loss of teeth during tooth replacement in children, in which case there is a certain pattern in the order and age of tooth loss. In the case of elderly people or those who lose teeth due to diseases or external injuries, there is no order and age rule. There are two teeth in a person’s life, including 20 milk teeth and 28-32 permanent teeth. Generally, around the age of 6, permanent teeth begin to gradually develop and erupt, and will replace milk teeth, and the phenomenon of tooth loss occurs. Usually, the order of tooth loss is also the order of eruption: 1. 6-8 years old: the central incisors (incisors) and the first molars (six-year-old teeth) begin to gradually develop and erupt, and will mostly follow the principle of first down and then up; 2. 8-9 years old: the lateral incisors and the first premolar next to the incisors begin to develop, gradually erupt and replace the original teeth; 3. 10-12 years old: the cuspids next to the lateral incisors and the second 4. 12-13 years old: the second molar will gradually erupt; 5. 18 years old: the third molar (wisdom tooth) will gradually erupt and last until about 21 years old, and some patients will not erupt for life. During the period of tooth replacement, parents should pay attention to correct the bad habits of children such as licking teeth and biting fingers, and pay attention to keep the oral hygiene to avoid bacterial growth causing dental caries and plaque. At the same time, intake of foods rich in calcium and vitamin D, such as milk, soy products, fish oil, animal liver, etc., will help the growth of teeth. In addition, elderly people and people who have oral lesions or external damage to teeth will also have the performance of tooth loss, but the order and age of tooth loss is not clear according to different factors such as personal condition and tooth stability.