The etiology of missing teeth is similar to the etiology of missing teeth, as follows: 1, each person will experience tooth decay from childhood, is one of the important reasons for missing teeth or missing teeth; 2, periodontitis: periodontitis is very common in the country, especially in urban and rural areas, and even the countryside than the city is more prevalent, due to the general population of the maintenance of oral hygiene, i.e., brushing, for the maintenance of oral health can not be enough to pay attention to, resulting in Inflammation of the gums around the teeth, or even cause bone resorption around the teeth, resulting in loosening, shifting, or even loss of teeth. Often patients’ teeth look good, but one by one fall off, just like the soil erosion on the mountain, the trees will fall off the same reason; 3, young patients often appear trauma, especially children about 10 years old, strong ability to act, but relatively weak sense of security, there will be trauma after the teeth knocked loose, knocked off, as well as fall off, belongs to the most common reasons; 4, hospitals will be common reasons The most common reason is that the teeth will be removed together with the tumor tissue due to tumor.