Nowadays, children's food is more and more exquisite, and a large number of dairy products, bread and puffed food make children's taste less and less effective. At the same time, children are more and more lazy to taste hard things, which makes the children's teeth and muscles inside and outside the mouth not get proper exercise, resulting in muscle weakness and atrophy, and then the jaw bone can not develop well, and the number of teeth has not decreased. So now the incidence of malocclusion in children is getting higher and higher. On the other hand, fine food is also convenient to cause tooth decay and tooth defects, leading to premature loss of primary teeth, resulting in insufficient eruption space for permanent teeth, thus forming teeth with uneven arrangement.