The citric acids found in fruit drinks can be more erosive than hydrochloric or sulfuric acid. These acids found, along with the refined sugar in soda, promote tooth erosion which wears away the hard part of the teeth, or the enamel. Once tooth enamel is lost, it's gone forever.
One beverage that does not produce such irreversible results -- brewed tea.
Researchers compared green and black tea to soda and orange juice in terms of their erosive effect on human teeth. The study found that the erosive effect of tea was similar to that of water, which has no erosive effect at all.
However, stay away from prepackaged iced teas, because they contain citric acid and high amounts of sugar.