Our kids got a bottle for as long as they wanted. Our pediatric dentist knew too. No big issue.
As long as they do not hold the bottle in their mouth while they're sleeping they are fine.
Bottles do not cause tooth rot. Dripping milk on their teeth all night while sleeping does. When they drink a bottle then put it down they are perfectly fine.
Think about it. If we all ran around brushing our teeth after we have a sip of coffee or pop, all day long...., or after we take a bite of anything we'd all be brushing our teeth all day long.
Our saliva has numerous jobs. One of them is to rinse our mouth. The saliva takes the particles and such away.
If saliva didn't work we'd all have mouths full of rotted teeth. But we don't and we don't brush all day. That's because we don't keep drinks and food constantly in our mouths all day. We eat and drink then saliva takes over.
We brush to get food particles deep between our teeth and to freshen our breath.
If your child is taking this bottle and then putting it down she's fine. Our pediatric dentist agreed with me when we talked.
I told him I'd rather have our kiddos take the bottle as long as they needed to suck instead of finding out that their thumb is a nice thing that fits in their mouth great AND it can't be taken away.
So you have to consider what benefit she's getting.
The biggest thing with me is this.
People who breast feed get to nurse as long as they want. They're told the longer the better, that kids who nurse longer are fine. They, for the most part, do not wean their baby off the breast the day they turn 1 then put them on a sippy cup with full vitamin D milk. Nursing mom's integrate other nutrition in their kiddo's diet but they continue to nurse.
So nursing mom's are allowed to nurse as long as they want and they are applauded for doing it.
Moms who give their kiddos bottles are ridiculed and told they need to wean them at age 1 and if they continue past that it's horrid. What hypocrites~
I think she should have a bottle until you are ready for her to stop. It's absolutely no different than letting her have a glass of milk with a snack at bedtime.