Cola dissolves enamel, and fruit juice did more of it in the same test
Over seven days of soaking, Coca-Cola took 7.5mg off enamel specimens and Coca-Cola Light 5.2mg, below the other eight drinks tested, fruit juices among them.
What the study found
Cola erodes enamel, and ranked least erosive of ten drinks tested
Over seven days of soaking, Coca-Cola took 7.5mg off enamel specimens and Coca-Cola Light 5.2mg — and both still came out below the other eight drinks in that test, fruit juices and Sprite among them. A separate lab test put Gatorade and Red Bull above either cola.
The caveat · Soaked a day or a week, no saliva
Both tests soaked teeth in the drink for a day or a week at a stretch, with no saliva rinsing between sips. In one of them the damage did not track a drink's measured acidity at all, so phosphoric acid's own share never separates from the rest of cola. The seven-day test used bovine enamel, a stand-in for human enamel rather than the thing itself. Twelve of the nineteen studies in the review are lab work too.