The view that “milk teeth have to be replaced sooner or later, and there is no need to treat caries” is extremely wrong. The caries of milk teeth has adverse effects on children’s oral cavity and organism. (A) Local influence 1.Impact on chewing function Caries causes tooth defect, secondary pulp disease, periapical disease, and finally leads to residual crown, residual root and tooth loss of milk teeth, and reduces or loses chewing function. 2.Impact on permanent teeth and permanent tooth series. The caries of milk teeth deteriorates the oral hygiene and makes the newly erupted permanent teeth occur; the further development of milk teeth caries, followed by periapical periodontitis, can cause the incomplete development of enamel of inherited permanent teeth, and also lead to the destruction of local alveolar bone, the abnormal resorption of milk teeth and the retention of residual roots, which makes the inherited permanent teeth erupt too early or too late, and affects the order and position of permanent teeth eruption. If the crown is damaged due to caries, the proximal and distal mesial diameters are reduced, or if the gap occupied by the inherited permanent teeth is reduced due to early loss of the baby teeth, the permanent teeth will have abnormal position when they erupt due to insufficient gap, resulting in malocclusion. 3, damage to oral mucosa soft tissues The crown, root and root tip of milk teeth can be exposed to pierce the oral mucosa and form ulcers. (2) Systemic effects 1.Most of the milk teeth with caries and crown collapse, the chewing function will be reduced, and the food will not be cut and ground sufficiently, which will increase the gastrointestinal burden and affect the nutritional intake of children; children are in the vigorous period of growth and development, so the growth and development of jaw and face and the whole body will be affected. 2.The chronic periapical inflammation transformed from caries can become focal tooth to cause focal infection in other tissues of the body, and the diseases related to focal tooth include hypothermia, rheumatoid arthritis, arachnoiditis, nephritis, etc. 3, early childhood is the period of children learning language, the chipping and early loss of milk teeth will affect the normal pronunciation, affect the beauty, will cause inferiority psychology to children and affect normal communication. It is suggested that children with tooth decay should be treated as soon as possible.