Drinking milk at night may cause dental caries or malocclusion, it is recommended to clean the mouth with finger cots after eating and drinking as well as to use the correct way of breastfeeding to minimize the damage to the teeth. 1. Tooth decay: breast milk or milk powder contains sugar, after drinking milk at night do not clean the teeth in time, bacteria will use sugar to cause damage to the teeth, so that tooth decay, it is recommended that after eating and drinking with finger cots gently clean the teeth teeth to reduce food residues. 2. Malocclusion: In the process of feeding, there is often a poor breastfeeding posture, resulting in the process of breastfeeding the lower jaw forward, long-term this way of drinking milk will lead to the teeth of the anticlinal, so in the process of feeding, you need to ensure that the correct breastfeeding posture. If the teeth are already malformed or decayed, you need to go to the hospital immediately to avoid aggravation of the symptoms.