YSK that SLS, an ingredient added to most commercial toothpastes, can cause mouth sores ( askthedentist.com )
I learned about this many years ago and the difference after I started using only SLS-free toothpaste was night and day. I used to get canker sores (mouth ulcers) any time I would bite the inside of my cheek, hit my gums with the hard parts of my toothbrush, etc., and this completely stopped a while after I switched to SLS-free....
