S.W.
There is no deadline for transitioning away from a bottle. And drinking from a bottle does not hurt their teeth. Putting them down to sleep with a bottle in their mouth hurts their teeth because the milk pools around the teeth and stays there. Just as constantly drinking from a sippy cup can hurt their teeth.
My daughter hated sippy cups - the only way she would drink from them is if we took out the valve (you have to suck really hard to get anything out of most of them). At 14 months, she learned how to drink out of a regular glass. All the kids in her daycare class did (at 14-16 months old) and hardly ever spilled. So we used bottles for milk, and regular cups at mealtime.
When I was a child, sippy cups didn't exist, they are a fairly recent invention, and they are not necessary.