In a small case study published in General Dentistry, Mohamed Bassiouny, DMD, PhD, professor of restorative dentistry at Temple University’s School of Dentistry, examined the teeth of a meth user, crack cocaine addict, and diet soda junkie. All three were longtime abusers—the diet soda drinker imbibed two liters a day for three to five years—and none visited a dentist regularly.  After a thorough examination of all three mouths, Dr. Bassiouny could hardly tell them apart. “The damage done to the hard dental tissue was almost identical,” he said. Dental erosion, or the dissolving of enamel, is the underlying issue here, thanks to all that acid. (Tooth decay is different: it leads to cavities, or little holes in the teeth.) Acid is a major cause of dental erosion, and since citric acid is in most fizzy drinks, regular pop isn’t exempt either. It’s hard to imagine chugging a two-liter bottle of pop a day, but it might take a lot less than that to experience dental erosion, according to a European study Dr. Bassiouny cited. “They actually said if you drink more than four 12-ounce cans a week, you enter into the zone of high risk for dental erosion,” he said. Our national average is 11-12 cans a week. Here’s the really scary part: you can have dental erosion—without getting to the meth mouth point—and not even know it. “It can be so small, it can be hidden,” Dr. Bassiouny said. “It’s sometimes mistaken as toothbrush abrasion.”  Moderating your soda habit is key, but pop is just one of the many acidic offenders in our modern diet. Check out the 25 Foods Dentists Won’t Eat for a not-so-toothsome menu.