There is a relationship between dental growth and bone, but the growth of teeth and bone is not exactly parallel because the embryonic origin is not identical. At birth, the milk teeth are already ossified, and the milk tooth spores are hidden in the jawbone and covered by the gums; the ossification of permanent teeth begins in the neonatal period, and the third permanent molars are ossified by 18 to 24 months of age. There are two sets of teeth in a person’s life: the milk teeth (20) and the permanent teeth (32). Milk teeth start to erupt 4 to 10 months after birth, and those that do not erupt after 12 months are delayed. The order of milk teeth eruption is generally lower jaw before upper jaw, from front to back, and the milk teeth are all erupted at the age of about 2.5 years. The first permanent tooth (first permanent molar, after the second molar) erupts around 6 years old; the milk teeth are replaced by the same permanent teeth one by one between 6 and 12 years old, with the 1st and 2nd bicuspids replacing the 1st and 2nd molars, which is a mixed dental period; the second permanent molar erupts at 12 years old; the third permanent molar (wisdom tooth) erupts at 17 to 18 years old. The third permanent molar (wisdom tooth) erupts at the age of 17 to 18, and there are also people who do not erupt the third permanent molar throughout their life. Teething is a physiological phenomenon, and individual infants may have low fever, increased salivation, salivation and sleep disturbance, irritability and other symptoms during teething. Healthy tooth growth is associated with nutrients such as protein, calcium, phosphorus, fluoride, vitamins C and D, and thyroid hormones. Chewing of food facilitates tooth growth. Diseases such as ectodermal dysplasia and hypothyroidism are seen in abnormal tooth growth.