Sodium lauryl sulfate (SLS) will negatively affect fluoride in toothpastes by reducing its bioavailability, which is counterproductive for cavity prevention.
How SLS affects fluoride in toothpaste
Studies have shown that sodium lauryl sulfate in toothpaste will decrease the bioavailability of fluoride by interfering with it's deposition onto the enamel surface.
Mechanism: SLS is a surfactant/detergent which wets the surfaces of the teeth to facilitate removal of debris, food, and plaque.
Unfortunately, it indiscriminately removes all substances on the teeth including fluoride which is supposed to stay on your teeth.
It literally cleanses away everything, the bad stuff as well as the good stuff.
What it means: Fluoride toothpastes that contain sodium lauryl sulfate will have a reduced anti-cavity effect when compared to toothpastes without it.
The cleansing effect of SLS effectively lowers/reduces/decreases the anti-caries potential of your fluoridated toothpaste.
This ingredient does NOT maximize the beneficial effects of fluoride.
The main takeaway is that the surfactants work against the protective effects of fluoride.
What about other toothpaste surfactants?
SLS is the most prevalent surfactant/detergent in oral care products but some toothpastes use different ones such as cocamidopropyl betaine, cocamidopropyl hydroxysultaine, sodium cocoyl glutamate and etc. (We do have a full list of toothpaste ingredients).
These other detergents within toothpaste should theoretically elicit the same negative effect on fluoride as SLS albeit to a lesser degree.
One study found that the cocamidopropyl betaine (CAPD) had better fluoride effects when compared with sodium dodecyl sulfate.
We can attribute this difference to the potency of strength of the detergents.
SLS is much more potent than the CAPD and thus should be more detrimental to fluoride.
Overall, we would have to say that a milder detergent would be better for maximizing the effect of fluoride. Although a toothpaste without any at all would be the best.
Is SLS bad for toothpaste?
Our dentists in Long Island City are not completely opposed to toothpastes with SLS in them because they do serve a specific purpose such as for teeth whitening.
You need a strong detergent in order to remove stains from your teeth. Without it, you won't be able to whiten as well. Therefore any whitening toothpaste that is worth its salt should have SLS in it. An example would be the colgate optic white advanced toothpaste.
However, if your main focus is on preventing cavities, you may want to choose one without SLS in order to maximize the anti-caries effect. An example would be the sensodyne pronamel intensive enamel repair which is SLS-free. Although a common complaint that we get with these toothpastes is that they don't quite foam as much.
Ultimately it comes down to what you're looking to get out of your toothpaste!
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