The causes of yellow teeth after tooth replacement in children include the following: 1, physiological phenomenon: the newly erupted permanent teeth enamel transparent, dentin color is yellow, and chalky milk teeth exist color differences, is a normal phenomenon. 2, poor oral hygiene: children poor oral hygiene cleaning, can not brush and rinse in a timely manner, a large amount of food residues and soft scale adhering to the tooth surface, so that the tooth surface yellow. 3, disease: suffering from dental fluorosis or 4, enamel surface defect: when the child suffers from enamel hypoplasia or poor mineralization, the enamel surface forms a substantial defect, which is easy to deposit exogenous pigment and soft scale, causing yellow teeth, and the defect needs to be repaired in time.