There's toothpaste out there claiming to contain liquid calcium. Which either a truly dangerous thing to have in your toothpaste, or a bald-faced lie.

That, I rather suspect, would be advertising being Bad Science - and actually means that they've got some form of squidgy calcium /compound/ in there, rather than the raw element. However.....

instant-mouth-ulcer-forming bicarbonate of soda

*blinks* This would be the same sodium bicarb popularly used as a raising agent in traditional baking? Admittedly it's usually gone through some chemical changes by the time it hits the mouth, but it's hardly what I'd view as a noxious chemical - practically, I've heard of undercooking causing rather more stomach upsets from the raw eggs, than the bicarb causing ulcers...

I went so far as to google briefly, in case I was being utterly insane here - and while I know google can be wrong, there was source after source actually listing sodium bicarb (either in connection, or actually applied direct as powder) in connection with mouth ulcers as a traditional remedy to soothe them, not a cause!

So, still confused...Source?