As a childcare worker, we are not allowed to let children fall to sleep with milk or anything other than water on their teeth. It is a reccomendation by dental associations. We give children their milk before bed and then they rinse their mouths with water then spit it out before laying down to sleep. It can be difficult to get children into this habbit after being in the habbit of drinking from a bottle and going to sleep with it in their mouth, but I have seen children with black teeth, decay and even teeth pulled out because they were so ridden with decay. My nephew is one. He had about 5 teeth pulled out when he was only 3yrs old (after having horrible decayse for 2ish yrs before that) because of having milk in a bottle to sleep with.

There are several reasons toddlers and young children shouldn't have milk before bed- milk is quite high in sugar, dental caries (tooth decay) can occur.
When a child drinks lying down, milk can flow through to the ear cavity, which can cause ear infections.
It has been proven that milk is bad for teeth when a child sleeps through the night with it on their teeth and formula is also not good. Usually milk caries can result from bottle-feeding children with formula, milk, cordial or fruit juice.
Once the first teeth begin to show, never allow your baby to fall asleep on the bottle. Gently extract them just as they begin to drift off and it is clear they are no longer feeding.

Helle,
Breastfeeding can protect teeth. Breast-feeding has only a very small risk of producing caries and that the benefits of extended breastfeeding (beyond 12 months) outweigh the low risk. But it is still a good idea not to let bubs fall asleep on the breast. While BM has healing properties, it also still has alot of sugar, and carries risks of damaging teeth.


This info is coming from a professional place. From a mummy place, I know how hard it is to not let children fall asleep on breast or bottle. Both of my children have gone to sleep on breast or bottle until they were about 18mths. Luckily for me they then weaned themselves from falling asleep that way naturally.
Good luck.