Canker sores. Ulcers in the mouth that hurt like a mother and stick around like a mother-in-law. I used to get those bastards, like, once a month before I read about Sodium Lauryl Sulfate, SLS-free toothpaste, and Verve. So, yeah, this is something I'm telling you about because I've actually tried it, and it actually helped me. Big time.
Doctors don't know exactly what causes canker sores, but think they're related to stress, tissue injury (e.g., from braces or chewing on the inside of your mouth like I do), and / or eating a lot of citrus or acidic food (if alcohol counts, that's me too.) More recently, they've also linked canker sores to SLS, an ingredient found in most toothpastes that makes them foam in your mouth. They think SLS dries out your mouth tissue, making it more susceptible to the other potential canker instigators.
Several studies on SLS have shown that eliminating it reduces the recurrence of canker sores, possibly up to 80%.
There are a few SLS-free toothpastes out there, and they probably all work just as well as Verve. This is the only one I've tried though because it worked from day one, and basically looks, feels, and tastes like normal toothpaste in every other way, so I haven't had to test out anything else. I've been using it for about 8 months and have only gotten a canker sore once when I forget to take it on vacation. I also haven't gotten any cavities or yellow teeth from it, so I'm pretty sure all of its other ingredients are the same as your favorite Crest or Colgate.