As a trained Health Visitor here in the UK I just wanted to say that we encourage mothers not to allow the child to do this with a bottle or for that matter when BF (if the child is demand bf and doing it constantly). I completely understand the argument for comfort, but when the child has teeth, having milk sitting against them for prolonged periods of time is incredibly bad for them and is probably the worse thing you can do to them. Teeth are only able to withstand three attacks of sugar a day, hence our three meals a day. We teach that if you are going to give your child anything sweet (chocolate, fizzy drinks etc) that you do it all in one hit, not in dribs and drabs throughout the day. Milk (breast and formula) is very high in sugar and is just as bad as juice/fizzy drinks on the teeth. Yes sucking is a response a child does for comfort but the best thing is either a dummy (pacifier) or a thumb (preferbly their own

). Yes there are problems associated with both of these particularly when they get older, but trust me, milk for prolonged periods of time against the teeth is much, much worse. When the child has a full set of teeth, we normally recommend milk be taken with meals, but if it is for comfort before bed ( I would never deny my own son this comfort) then teeth need to be cleaned afterwards (same in the morning).
Sorry to harp on about this, but I have seen what milk can do when demanded and it is not pleasant. Black rotten teeth is embarresing for the child (can lead to low self esteem) and can lead to needing an extraction. Incidently first teeth are very important partly for speech development (not an expert in that area) and also to "show" the second teeth the way to go to become straight.
It really is not a bad thing for a child to realise that it is not always going to get what it is demanding, particularly when it comes to milk. We don't always get what we want in life and there are plenty of healthy alternatives if the child is hungry, which actualy would benefit the child a lot more eg fruit, nuts, seeds etc, (sorry I am being rather general here, I know there are inviduals who have to be careful here).
Breast/bottle feeding should be acceptable anyplace/anywhere, especially if that is the baby's main source of nutrition. Also wanted to mention that just like there is plenty of evidence found into the benefits of prolonged bf, there is plenty of evidence found into the disadvantages of prolonged bf, or perhaps a better way to say it, the benefits into not prolonging bf. What I am saying is that you have to weigh arguments up and work out what is best for you. I will say on a personal note though, we are not animals and neither are we living in a aboriginal tribe, so those arguments are slightly weak. I do however respect everyones choices and just wish I could have bf my son longer then the three months I was able to achieve. I remember when I decided to stop bf (for a multitude of reasons) it was so hard. Everytime I dropped a feed it was like loosing a very close tie. The last one I dropped was just horrible so I can understand why prolonged bf happens.