My parents pamper my daughter a lot and keep giving her chocolates and sweets, which is not good for her teeth. How do I wean her off the habit?

I suggest that you firmly ask your parents to stop giving her sweets and let them clearly see the reason why. Reiterate to them that you want to discipline your daughter on her food preference because the consequence of this is long term. They will understand. Then start introducing fruits and vegetables and cereals. And throw all chocolates inside the house. :)