I used to have a lot of trouble with mouth ulcers (you guys probably call them 'canker sores'), this was an ongoing issue for 10 years or more. Anytime I bit my lip or cheek, or even just a minor abrasion to the lining of my mouth, and I would be guaranteed to get a mouth ulcer. Tried the usual antibacterial type remedies such as topical peroxide, iodine, bicarb, salt, rinsing with alcohol. That stuff didn't work for me though.
In the end my ulcers turned out to be caused by a virus (maybe a strain of HSV), and a potent anti viral called BHT worked for me - from what I read it only works for lipid-coated viruses (fortunately the majority of viruses are lipid coated!). I took about 500mg of BHT twice a day and that fixed it. And by fixed I mean I'm practically cured, as I don't need to take a maintenance dose of BHT to keep the ulcers away. 500mg worked, but maybe 250mg would be fine too, but I know that taking 1000mg in one dose was too much for me to handle as I would get some pains in my tummy (possibly liver struggling to metabolise it).. that only lasted an hour or so.
-- Update :: I posted the following on EarthClinic.com --
BHT is what worked for me. I tried the usual antibacterial modes (iodine, salt, baking soda) and nothing would help one little bit. Any time my mouth had a little scratch it would inevitably result in a mouth ulcer that would take weeks to heal (you guys call them 'canker sores').
I eventually tried BHT thinking it might help some other immune problems (I have an inflammatory autoimmune disease). Well, only one thing changed noticeably - no more mouth ulcers. Ever since trying BHT I have been clear of this issue, and it has been a stark change. Now if I bite my lip there is no problem, yet before I would be absolutely guaranteed to have a very nasty canker sore.
Now I can't guarantee this will help anyone else, I never expected that my mouth ulcers could be caused by a virus!! (ehh sorry I mean 'canker sores) But there you go.. learned something new. I suspect the majority of folk are still caused by bacteria, but hey if iodine, ACV, baking soda and salt don't help then maybe you should try this!
You can read more about BHT here: http://www.projectwellbeing.com/wp-content/uploads/2011/02/BHTbook-StevenWmFowkes-100903.pdf
Most important - make sure it is food grade.