Enamel development is not only regulated by genes, but also serious localized oral infections or systemic diseases during the development of tooth germs can cause abnormal function of enamel-forming apparatus. I. Etiology 1. Systemic diseases of mother or baby: During pregnancy, if the pregnant woman suffers from viral infection or toxemia, it may cause enamel underdevelopment of the fetus. Pediatric herpetic diseases, such as: chickenpox, measles, etc. can also interfere with the function of enamel-forming cells, resulting in enamel development abnormalities.2, nutritional metabolism abnormalities:Vitamin D deficiency caused by rickets, dental development will also be impaired when vitamin A.C deficiency can also cause enamel hypoplasia.3, endocrine disorders enamel bio-mineralization and the collective calcium and phosphorus metabolism is indistinguishable from parathyroid adenosine on the dental The influence of parathyroid hormone on the mineralization of teeth is also great, when the secretion function is abnormal, it can also cause enamel or dentin development abnormality. Local factors during the development of tooth germ, trauma or local infection, can damage the developing tooth germ. In the periodontal infection affects the lower or adjacent permanent tooth germ, it can cause enamel underdevelopment of these permanent teeth. Second, the clinical manifestations of the enamel surface can be chalky spots, the form is basically normal, serious cases can appear point-like, line-like, band-like or depressed defects, defects often have color changes. However, the surface of the defect is generally smooth and hard. It is common in permanent teeth, and in general, systemic disorders are more likely to occur during the first year of life, when tooth replacement occurs mainly in the incisors, cuspids, and the incisal edges or cusps of the first molars. The cusps of the lateral incisors develop slightly later, and when the cusps of the lateral incisors are involved, the disorder generally occurs around the second year. Enamel development of the premolar and second molar teeth generally begins in the 3rd year of life, and thus when developmental disorders occur in the 3rd year of life, they generally do not involve the premolar and first molar teeth. Can be in the teeth of the incisal edge or cusp of the teeth such as no enamel, there can be symptoms of dentin hypersensitivity. Third, the prevention and treatment of enamel due to the developmental abnormalities caused by environmental and other factors, structural defects can occur, and such defects are irreversible. Therefore, prevention should be the mainstay to minimize the chance of infection in mothers and children. Prevent systemic infections and periapical infections of milk teeth. Dietary food containing much vitamin C such as fresh fruits and vegetables, and food containing much vitamin D such as all kinds of liver, egg yolks or all kinds of finished cod liver oil are recommended. Symptomatic treatment: hot and cold stimulation pain can be desensitized with drugs, the defect is obvious, filling surgery, anterior teeth can be used composite resin filling, veneer method or porcelain crown repair to improve the symptoms and aesthetics.