Changing teeth at the age of 5 and a half is not a calcium deficiency, because nowadays children are somewhat more developed and better nourished, and there is no direct relationship between whether there is a calcium deficiency and the time of tooth replacement. The development of the tooth first forms the germ, which gradually develops into a tooth and then erupts into the mouth, so it already starts to calcify when the tooth is in the germ. The tooth is already in the process of calcification during pregnancy, and the early or late eruption of the tooth replacement process is a result of various factors, and the state of development and the calcification of the tooth are two concepts. The teeth are calcified before the early eruption, the time of eruption is mainly related to the early and late development of each child, after the eruption in the environment of oral saliva, there is a long-term calcification process and the exchange process between saliva, which is relatively slow, the most important developmental stage is at the stage of the dental embryo. The eruption and mineralization of the tooth are two different stages. Tooth mineralization usually begins when the germ is formed, and eruption is mainly related to the child’s own late development.