Take this with a grain of salt because I don't have the references to give you on this but I have read that bottles can affect the development of teeth (adult as well) and jaws if given throughout the toddler years. Maybe you could ask a dentist about it. And if you decide to try and get rid of the bottle you could try why my mum did with me when I was about 3 - a MAJOR bribe. Basically I was told that getting a puppy meant I had to give my bottle up. I still remember ceremoniously handing over my bottle to the breeder! And apparently there was never another word on the topic. I know you're not supposed to bribe kids but maybe on the really big things it doesn't hurt to have a bit of a reward for giving up a much loved comfort.