This isn't an herbal topic, but didn't know what category to put it under. It is based on my personal experiences and may or may not be of use to anyone here.
I suffered from canker sores for many years until I finally "discovered" (suggested by a dental hygienist who also got them), that for me, sodium laurel sulfate was a "potentiator" of the sores.
There are two main types of canker sores (I'm not including oral lesions of herpatic origins here) Aphthous Major and Apthous minor. Most people are familiar with the minor form.. usually a small (about 1/3 of an inch or smaller) slightly irritating but minimally painful sores. The major type are a whole different ball game. They are excruciatingly painful, tend to inflame the nerves near them and also cause swollen lymph painful lymph nodes on the affected side of the mouth, chin and jaw. The swollen lymph nodes can cause severe ear aches. The pain makes it hard to talk, to eat, or sometimes to move your tongue or swallow. They can be quite large-- I would consider one a half inch as small. I've had several which have been larger than a quarter in size. At one point, I think I'd tried everything available over the counter. Doctors aren't used to seeing them and I had some pretty wacky diagnosis, as well as very expensive mistreatments. Most of my sores started with some sort of abrasion to my mouth (a scrape from a potato chip, crispy cereal was something I didn't dare eat!). Trips to the dentist were a nightmare, not immediately of
course, but within about 5 days, things would get stirred up, then it would take another three weeks for the sores to heal. These sores leave horrible scars behind.
Ok, long story short:
I quite using any toothpastes with Sodium lauryl Sulfate, now use biotene. I only use biotene mouthwash. I have a prescription on hand at all times for Triamcinolone Dental Paste (something that most doctors and dentists haven't heard of.... if I have to change providers, I get the information to them, I INSIST on having a prescription of this on hand). IF I start to get a canker sore, I use the dental paste on it. That usually stops it from developing further. Since switching away from SLS, I don't think I've had one sore that has ever been bigger than a nickel. I've not had one that lasted two full weeks.. and I'm down from a couple a year to once every four or five years! That's a significant improvement.
When I get sores, I do avoid certain foods (because they cause the sore to immediately hurt), Walnuts, avocados... etc.
I hope this helps someone!