Canker Sores....cause and treatment???

Hi to anyone that may have the answers. My husband seems to get quite a few canker sores and I'm not quite sure why. I told him that I would go into research mode and try to figure out why he is getting them and perhaps a natural solution that he can try. They are painful and I'm sure, unnecessary. I sure hope that someone knows about this. I did a google search and the only thing I can come up with as a cause is toothpaste. I shall certainly look into all this . Thanks so much for any insights. Tweet