Might Mean: You’re suffering from acid reflux -- a condition in which stomach acid splashes back up into the esophagus and, in some cases, all the way to the mouth, causing heartburn and a sour taste. Typical triggers include spicy foods and heavy lifting, as well as lying down immediately after meals. “Over time, this acid can erode tooth enamel giving your teeth an opaque cast,” explains Cleveland-area dentist Matthew Messina. To nix reflux, reduce your intake of acidic foods like citrus fruits and sodas and avoid eating two hours before bed, suggests Russell Maier, M.D., a family physician in Yakima, Wash. To tweak your teeth, speak with your dentist, says Messina. He or she can easily apply some bonded composite (tooth-colored filling material) to transform teeth back to their original appearance.