1.Eating slowly, containing food without swallowing, playing while eating, still drinking milk and drinks from bottles after 1 year old, always have the habit of drinking milk before going to bed or in the middle of the night, and fall asleep with milk bottles in their mouths. 2.Like to eat cookies, bread and other foods that stick to the teeth easily, and frequently drink various drinks such as carbonic acid. 3, very frequent eating, the mouth has not been able to maintain oral hygiene, oral bacteria will continue to break down the food acid production, resulting in tooth demineralization “worm teeth”. 4, brush teeth is not serious. Every side of the teeth should be brushed, do not miss the surface of the teeth, upper and lower molar occlusal contact surface, prone to “worm teeth”, parents should assist in guiding children to brush their teeth and check, and gradually transition children to brush their own teeth. It is not easy to brush the uneven teeth. 5, poor general health, low resistance, dental development defects