All types of milk can cause cavities if they are inappropriately consumed. For example, cavities on the upper front teeth can develop if a baby with teeth is put to bed at night with a bottle of milk. However, plain cow's milk typically does not cause cavities if it is given in a cup with meals.

Can milk rot your teeth?

Milk, despite helping your teeth stay strong, contains lactose, which is sugar. It is still broken down by bacteria in the same way that it breaks down fructose and glucose. As the sugar is broken down, acid is produced that causes your teeth to decay.

Does milk before bed rot your teeth?

Lactose is sugar, and sugar should be avoided before sleeping. Milk that lingers on your teeth can cause damage. Without brushing your teeth after drinking milk (especially at night before sleeping), the sugar in milk will stay on your teeth. This will lead to cavities and decay.