We’ve all heard it from as far back as we can remember: Soda is bad for our teeth. Dentists, parents, teachers, even Sesame Street and Mister Rogers made sure we knew all about tooth decay. Yet 48 percent of Americans drink an average of 2.6 glasses of soda a day. That’s 45 gallons of pop a year just eating away at our pearly whites.

So we’ve already established that we’re basically poor listeners when it comes to protecting our tooth enamel. But maybe we just don’t understand what makes it so bad. Did you know that diet soda is just as bad for your teeth as its classic compadre? And even fruit juices — while healthier overall—can harm our teeth if we don’t properly manage our tooth care. Why? Because sugar isn’t a smile’s greatest enemy, acid is. And diet sodas, as well as some fruit juices, can have just as much acidity as some regular sodas.

When it comes to liquids, the lower the pH, the higher the acidity. Plain ol’ natural water is the best for your teeth with a completely neutral pH level of 7. But everything else — even milk — has acid to some level. Milk’s pH is just slightly lower than water at 6.5, and black coffee slightly lower than that at 6.3. Acid begins to dissolve tooth enamel at a pH of 5.5. And the safest of the major soda brands — Dr. Pepper — comes in at a pH of just 3.4.

Soda acidity just continues to get higher, with Sprite at 3.3 and Mountain Dew at 3.2. Coke and Pepsi disturbingly have the same pH at vinegar, a highly acidic 2.5.

Still, there a few techniques that might save you from mouth rot. Obviously, reducing the number of acidic drinks you consume will do the trick. But if you’ve just got to have that can of Coke to make it through the day, use a straw and place it toward the back of your mouth to keep more of the liquid from immersing your teeth. Don’t swish acidic drinks. And once you’ve finished your acidic drink, wait as long as reasonably possible before brushing your teeth — brushing too soon will actually erode your enamel faster. Now, why didn’t Mister Rogers ever tell us that?