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.
SLS is Sodium Lauryl Sulfate, by the way, and it’s a detergent. From what I understand, the only reason why it’s added to toothpaste is to make more foam when you brush. But the SLS-free toothpaste I use makes plenty of foam, so I have no idea why they add it. It’s one of those things about the modern world that makes absolutely no sense. The ads and packaging should say in big letters: “now with even more canker sores!”
Unfortunately, the vast majority of toothpastes on the market (at least in the US) have SLS. I can only seem to find SLS-free toothpaste in natural food/supplement stores. It’s extra difficult to find toothpastes that are SLS-free but that keep fluoride too. The difficulty (and price? I haven’t compared) is completely worth it to me though.
TL;DR: The SLS (Sodium Lauryl Sulfate) in most toothpastes is unnecessary and (edit: CAN cause) canker sores (painful sores in your mouth and gums). If you have this problem, you will likely benefit from SLS-free toothpaste (some still include fluoride) that you can usually find at natural food stores.
I think the article is misleading. The studies don’t seem to show that SLS causes canker sores, but if you do suffer from them, it will exacerbate them or delay their healing. The article says “studies”, while only citing one study, that actually recruited patients who already suffered from the sores. A double blinded cross-over trial concluded that “The number of ulcers and episodes did not differ significantly between SLS-A, SLS-B, and SLS-free. Only duration of ulcers and mean pain score was significantly decreased during the period using SLS-free. Although SLS-free did not reduce the number of ulcers and episodes, it affected the ulcer-healing process and reduces pain in daily lives in patients with [canker sores].” Although I don’t have access to the full version, so I can’t view the details. By the way, SLS-A was an SLS-free toothpaste spiked with 1.5% SLS, and SLS-B was a commercially available toothpaste with 1.5% SLS in it already.
You can tell that the article is trying to sensationalise something by such phrases as:
“But there’s no reason to accept a hazardous chemical in your toothpaste.” You know what else is in your toothpaste? Sodium fluoride. Which is lethal at high enough dose. It’s all about the concentration.
“It’s strong stuff — the cleaning solution I use on our garage floor is 50% SLS.” Well, yes, if you use it at concentrations ridiculously above the ones found in a toothpaste, of course it’s going to be “strong stuff”. You know what else is strong stuff? 100% acetic acid. Yet somehow, at 10% we happily consume it as vinegar. By the way, vinegar - great cleaning agent!
Don’t get me wrong, if you’re sensitive to SLS, by all means avoid it. But I’m not a fan of articles that make blanket statements about a chemical that is mostly harmful in the concentration that it’s used in hygiene products. It’s another one of those “aspartame gives you cancer” (which it doesn’t by the way).