A Quiet Change in Your Toothpaste, Reviewed
Several years ago, major dental manufacturers started to switch the active ingredient found in many toothpastes from sodium fluoride to stannous fluoride... However, because these are two different chemicals, there are differences in how they affect your overall oral health.
Literature Sources
1) "Effect of sodium, amine and stannous fluoride at the same concentration and different pH on in vitro erosion" (2009) by Annette Wiegand and others. Link to Article.
2) "Efficacy of sodium and stannous fluoride mouthrinses when used before single and multiple erosive challenges" (2016) by S O'Toole and others. Link to Article.
3) "Stannous Fluoride Preventive Effect on Enamel Erosion: An In Vitro Study" (2020) by Alessandra Lucchese and others. Link to Article.
Several years ago, major dental manufacturers started to switch the active ingredient found in many toothpastes from sodium fluoride to stannous fluoride. There wasn't a big marketing push to broadcast the differences between these two chemical compounds as they both contain fluoride, a well-known element for reducing and preventing tooth decay. However, because these are two different chemicals, there are differences in how they affect your overall oral health.
Researchers in study #1 decided to compare the protective effects of sodium fluoride against stannous fluoride in an in-vitro experiment. They first obtained cow teeth (enamel of teeth) and divided them into multiple groups. One group was coated with sodium fluoride, another with stannous fluoride, and a control group without fluoride. They then put the teeth into an artificial mouth and doused them for 90 seconds with hydrochloric acid six times a day for 3 days to trigger enamel degradation. At the end of the experiment, the researchers compared enamel loss of the experimental groups to the control group and noticed that only stannous fluoride had a statistically significant improvement in enamel loss compared to the control group (no fluoride). The sodium fluoride-treated group trended to improvements in erosion but was still statistically comparable to the group without any fluoride.
This outcome is similar to another study (#2) that looked at the effects of stannous fluoride and sodium fluoride on human teeth in an in-vitro experiment. Teeth were either dipped in a stannous fluoride solution, sodium fluoride solution, or water for 1 minute then dipped in a citric acid solution for 10 minutes. This cycle was repeated 4 more times. Researchers noted that after the first cycle, teeth in both experimental groups showed protective effects against the acid compared to the water control group; however, after all five cycles were completed, the tooth erosion in the sodium fluoride-treated teeth was statistically similar to that of the untreated water group. Only the stannous fluoride-treated group continued to offer protection against the acid.
That phenomenon was also noticed in study #3. In that experiment, researchers divided teeth from humans into experimental and control groups. They further divided the experimental group into one treated with stannous fluoride and another treated with sodium fluoride. The teeth were again divided into smaller subgroups and paired with teeth from the control group then dipped in various acids (citric acid, hydrochloric acid, lactic acid) per group for 5 minutes.
Afterward, researchers analyzed the structure of the teeth using a scanning electron microscope. They noticed that teeth from the control group suffered from more demineralization compared to teeth in both experimental groups. The sodium fluoride group showed areas protected from demineralization in all acid subgroups and the stannous fluoride group showed areas of acid-resistant deposits on the teeth in the lactic acid subgroup. The researchers believe that stannous fluoride works by building a resistive metallic layer of stannous fluorophosphate on teeth that protects them against successive acid exposures. Sodium fluoride, on the other hand, is best suited for one-time acid exposures.
What Does This Mean For Me?
With the prevalence of stannous fluoride-containing toothpaste growing, it may be more difficult to find toothpaste with sodium fluoride. Based on public research, stannous fluoride seems to offer better long-term protection against dental cavities when compared to sodium fluoride. Unfortunately, the major concern with using stannous fluoride on teeth is the risk of tooth staining. Sodium fluoride does not have the same staining risk. The stains themselves are not permanent and can be removed by a dental hygienist. Also, there are newer toothpaste formulations of compounds containing stannous fluoride that are designed to decrease the chance of staining.
Many people are unaware of the ingredients inside common products that they use and do not notice when manufacturers change core ingredients, especially when the exterior branding remains unchanged. It is important to read the ingredients on the back of the box to determine if what you buy is what you expect to buy.
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