Everyone knows soda rots your teeth. I mean, isn't it true that if you leave a tooth in a glass of soda for a couple days, it will begin to soften and disintegrate?
Actually, that's an urban legend. The next time your kids lose a tooth, try it for yourself and you'll see the tooth remains intact.
Though soda contains citric and phosphoric acids, so do plenty of other foods and beverages. Grapefruit juice, for example, is even more acidic than Coke. Usually, though, your saliva can neutralize these acids without a problem, plus your teeth get extra protection from their enamel coating.
This evidence would lead us to believe we can drink all the soda we want!
However, if you nurse a soda all day long, or drink it when you're dehydrated and your mouth is dry, you might run into problems in the long term. If your mouth is healthy, the thing you need to be concerned about isn't acid so much as sugar. Bacteria that live in the mouth ingest the sugar the soda leaves behind and produce acids that eventually destroy tooth enamel and lead to tooth decay.