Here’s a serious medical subject that clearly needs more funding. Foods that rip up your mouth. Swiss cheese for example. It tastes so good that I can’t resist throwing several slices on my ham sandwich, even as I know that in 10 minutes the roof of my mouth will be burning and itching. The same with salt and vinegar pototo chips. These are sooooo good I can’t quit eating them even knowing the price. It might be a genetic allergy, my dad suffers from the same thing. It’s not a general mouth weakness type problem, because I love hot peppers, and used to eat habaneros(until my stomach decided this was not a good thing), without mouth problems. Anybody know what causes roof-of-mouth irritation, and how to prevent it, or toughen up my mouth against it?
Dentures 
In the vast pantheon of Foods Which Cause Actual Physical Damage to Mouths, the ruler is the notorious Captain Crunch.
If only it didn’t taste so good. Mmmm… crunchberries.
Adding to MrVisible’s list: pineapple and kiwi. I have to ration myself when I eat either or my mouth burns for the entire day after I pig out.
I don’t know what causes, but can guess certain acids in the food(s) cause the problem, but how to prevent it, I don’t know. I wonder if the old poison trick will work. Slowly ingest more and more until it doesn’t bother you anymore 
Those two do it for me too - both highly acidic. I don’t think the old poison trick works - I was fine with both until I started eating them regularly. Now my mouth itches and my throat starts to swell 
Regarding cheese:
and kiwis:
Damn. There goes my planned career change.
For some reason, a lot of people I know will mysteriously develop one or more canker sores on their tongue or inside their cheek after eating pineapple, but only fresh pineapple.
My guess is that, in addition to the acidity, fresh pineapple contains some kind of enzyme which affects the lining of the mouth. Since pineapple is heated during the canning process, the enzymes are destroyed.
Anyway, besides Cap’n Crunch, Fruit Loops and Apple Jacks always tear up the roof of my mouth. Not nearly as bad as that curtain rod did when I was 4, though.
**Sir Doris- **do fresh cherries make your mouth itch as well? I get the mouth itchies from fresh pineapple, fresh cherries, and brazil nuts. Cooked pineapple and cherries have no effect, but cherry flavored bazooka joe bubble gum does. Rather odd, that.
**Wonko ** - I haven’t noticed a problem with fresh cherries, but I don’t get them very often, they have a fairly short season over here. I guess I’ll be able to find out in a month or so. I get it with grapes, sometimes (but not wine, so that’s ok!).
I had a look through a few of the allergy sites, the advice being to avoid any troublesome food for a while, then try again. Unless you have a severe allergy, of course. They basically say that if you continue to eat the stuff you’ll make the allergy worse. It makes sense to me - the problems surfaced when I was on a big health kick focussing on kiwi, pineapple and various “exotic” fruits.
As with you, cooked fruit is no problem, nor, I find is juice (presumably this is also heat treated).
Ah well, looks like I’m forced to eat ice cream
Don’t get me started on ice cream!