Milk teeth are more prone to caries than permanent teeth, which is related to the anatomy and morphology of milk teeth, tissue structure, degree of mineralization and the environment in which they are located and other factors. 1, the anatomical form of milk teeth and tissue structure characteristics of the factors of milk teeth fossil fissure point gap complex and irregular morphology and teeth in the physiological gap is easy to retain food, it is not easy to clean; milk teeth two neighboring teeth for the surface contact, than permanent teeth point contact self-cleaning effect is poor. Milk teeth body is small and thin, poor calcification, low hardness, weak acid resistance. 2, children’s habits factors Children eat more often, less food fiber, soft, sticky, sugary, easy to stay on the tooth surface fermentation acid; children’s oral self-cleaning and cleaning role is relatively poor, due to the children’s long sleep, oral activities, salivary secretion, self-cleaning role is poor; age, gargling, brushing the teeth of the cleaning role is poor. 3, early detection, early treatment difficulties Mammillary caries more self-conscious symptoms are not obvious, therefore, often appear obvious symptoms before going to the hospital.