Is it true that a baby's teeth decay if they fall asleep with a bottle?

Yes, it is true. Nursing bottle caries is decay that spreads quickly from the upper front teeth because of the habit of falling asleep with a bottle, and it can appear even around a baby's first birthday. Saliva flow drops during sleep, so the sugar in the milk stays on the teeth much longer. To prevent it, 1) wipe the teeth with damp gauze or an infant toothbrush after feeding, and 2) start reducing night feeds around the first birthday. However, if you see a white band or brown spots on the front teeth, that is already an early cavity, so come in right away.