Milk teeth are a major component of the chewing organ during infancy, toddlerhood and school age. During infancy and early childhood is the period of vigorous growth and development, healthy milk teeth help digestion and facilitate growth and development. The caries of milk teeth develops quickly, and the tooth body can be crumbled quickly due to the caries, and it is easy to turn into pulpitis and periapical inflammation in a short period of time. The periapical disease of milk teeth will destroy the periapical tissues and lead to the destruction and resorption of milk tooth roots, and the premature loss of milk teeth will affect the chewing function of children, and then affect the digestive function and growth and development of children. At the same time, premature loss of milk teeth is not conducive to the eruption of permanent teeth and the formation of permanent tooth rows. On the other hand, once periapical disease of milk teeth destroys the periapical tissues, it can further affect the development of the permanent tooth germ below it and make its enamel development incomplete. Untreated periapical disease in milk teeth is also often a site of infection causing systemic disease. Therefore, once a pulpal infection occurs in a baby tooth, a thorough root treatment should be done.