Enamel hypoplasia is a disease caused by an impairment in the formation of the enamel matrix, which is an abnormal development of the tooth structure. Enamel hypoplasia can be divided into genetic and environmental causes of enamel hypoplasia with local, genetic and systemic causes, such as congenital syphilis, malnutrition, infectious diseases, etc. Enamel hypoplasia is a reduction in the amount of enamel formation rather than a reduction in the quality of mineralization, and the specific etiology is as follows: 1, maternal rubella and toxemia during pregnancy, and hyperthermia during infancy, such as pneumonia, measles, scarlet fever, diphtheria, etc. can lead to occurrence; 2, malnutrition, rickets, vitamin A, vitamin C, vitamin D and calcium deficiency and immunogenetic factors; 3, periapical infection of the milk teeth The periapical infection of any milk tooth can also cause enamel hypoplasia if it involves the permanent tooth germ. The specific clinical manifestations are several: 1) color change, brown in color; 2) banding and depression; 3) parallel horizontal lines can be seen on the tooth surface; 4) incisal margins become thin; 5) apical defects or disappearance of the posterior teeth. It usually occurs symmetrically, as multiple defects, and can be classified as mild, moderate, or severe according to the course of the disease.