Too much milk in toddlers can cause tooth decay eventually especially if the toddler drinks most of their milk from a baby bottle.
However as long as you make sure the toddler brushes his or her teeth daily then it shouldn't be a problem and the milk will be good for the toddlers bones.
So the toddler will have stronger bones when growing and be healthier overall when drinking a lot of milk.
Toddlers should drink a few bottles of milk per day along with other liquids but if you allow the toddler to take a bottle of milk to bed then it could lead to tooth decay if the toddler falls asleep with the bottle and milk in their mouth.
The same goes for juices and other sugary drinks in a bottle or sippy cup.
The toddler shouldn't go to bed with a bottle or sippy cup.