Is diet cola less bad for your teeth than regular cola?

Yes and no. : The high acidity will still erode your teeth. However there is no sugar in diet soda, so you are less likely to get cavities.

Yes: Yes, diet cola is far better for your teeth than regular cola. The cause of tooth decay is acid attaching the enamel. Sugar and other carbohydrates are consumed by plaque bacteria, the bi product of this is plaque. Plaque is very acidic and breaks down the enamel. Sugary soda is the perfect storm to assist this decay process. Diet is acidic but does not have a fermentable carbohydrate, sugar.