Is apple juice bad for your teeth? Well.. Apples are great for your teeth, why would apple juice be bad? That's logical, but..
Apple juice contains many sugars and acids. Apples do too, but when you eat an apple, the water and fibers inside of it wash away the acid and sugars. Juice doesn't have fibers or water, it can weaken and erode the enamel.
It has been found that orange juice decreases hardness and increases roughness of enamel... Enamel hardness was decreased by 84 percent. That's right. It was literally washed away.
It is important to understand that there are a lot of acids in fruit juices, sodas, energy and sport drinks. It is very important on how the drink is drunk, if you slowly sip it through 20 minutes, you are way more likely to have tooth erosion, than someone who drinks it in a few minutes.
Just a small sip leaves your teeth getting attacked by sugars and acids for twenty minutes.