For the vast majority of the populace, fluoride is simply just fluoride to them. However there are actually different types of fluoride that are present in toothpastes.
- Stannous fluoride
- Sodium fluoride
- Sodium monofluorophosphate
- Amine fluoride (available in swiss toothpaste Elmex but not in the US)
We are making a clear distinction among the different types because some of them can be used to treat sensitivity. For instance, toothpaste with stannous fluoride has a sensitivity reducing effect when used daily twice a day.
Are you curious as to why it can alleviate discomfort while the more common sodium fluoride is unable to? Well that is because fluoride can do much more than just fight tooth decay. So are you ready to learn about its anti-sensitivity property?
Is stannous fluoride good for sensitive teeth?
Yes, stannous fluoride is good for treating sensitive teeth because it reduces symptoms by occluding the open dentinal tubules.
A study from the Journal of the American Dental Association, found that a stannous fluoride toothpaste significantly reduced dentinal hypersensitivity after 8 weeks when compared to a placebo.
- The tubules were occluded with a deposit consisting of tin, zinc, phosphate, and silicon.
- Stannous fluoride occluded 82% of the open tubules vs the placebo’s 35%.
- There were improvements in tactile dentinal hypersensitivity scores of 27.8% and 42.0% and in air blast hypersensitivity scores of 21.4% and 32.3%, respectively, relative to the control toothpaste.
In other words there were statistically significant differences in all measures of sensitivity from using it. Basically it works in minimizing and preventing teeth sensitivity after 8 weeks of use.
Examples of stannous fluoride toothpastes:
- Crest pro health bacteria shield and gum
- Colgate total mint gum health
- Sensodyne sensitivity and gums
Side effects
Stannous fluoride may be effective as an anti-sensitivity dentifrice but it is not without any downsides. An unfortunate side effect of using the stannous version of fluoride is that it can potentially stain your teeth.
Despite it being patented in 1953 and being the first fluoridated toothpaste to gain the seal of acceptance by the ADA (american dental association), the teeth staining side effect could not be ignored.
One of the earliest studies that noticed this adverse effect was in a 1982 study in the European Journal of Oral Sciences. A yellow-golden stain was found on the teeth of the experimental rabbits that used stannous fluoride.
- The Tin (Sn) of stannous fluoride (SnF2) was interacting with the sulfhydryl groups to form stannic sulfide, which caused the staining.
- The sulfur in our mouth comes from the resident bacteria. After all it is due to the volatile sulfur compounds (VLCs) that cause bad breath.
All of this may sound disheartening but the good news is that there has been advancement in recent technology. According to a study in the Journal of the American Dental Association, the newer stannous fluoride toothpastes have reduced teeth staining compared to the prior iterations.
However, you should be cognizant that they used the word “reduced” and not “eliminated”. That implies that it still does stain but just not as bad as before. This is an improvement and we should all be grateful for it! Perhaps in the future they will completely get rid of the yellowing.
How does stannous fluoride reduce sensitivity?
The stannous version of fluoride occludes open dentinal tubules, which blocks the sequence of pain generation from the tooth nerve. This is different from how potassium nitrate in Sensodyne works, which interferes with the depolarization of the nerve.
Open dentinal tubules lead to sensitivity
Under normal circumstances, dentinal tubules should be closed because smear plugs clog up all of the openings. However under acidic conditions or patients with chronic sensitivity, the smear plugs may be missing.
The open dentinal tubules may result in teeth sensitivity due to changes in fluide movements within the tubules. According to the hydrodynamic theory of dentinal sensitivity, your tooth has receptors that can sense these fluid movements. A pain signal is generated when it senses the fluids being pulled towards or away from the tooth.
When all of the orifices of the tubules are closed, the tooth isn’t exposed to any stimuli and thus no fluid movement occurs. Wide open ones however can affect the fluids within the tubules.
Occluding tubules decrease teeth sensitivity
Literally blocking off the orifices of the tubules by occluding them will decrease teeth sensitivity. It acts as a physical barrier that prevents stimuli from affecting the tooth.
Studies have shown that brushing with stannous fluoride will rapidly recreate this smear layer that plugs all of the openings. The tin in SnF2 interacts with other molecules to form a deposit of zinc, phosphate, and silicon which plugs up the orifices.
An additional effect of this stannous fluoride created plug is that this new smear layer is more acid resistant. It will prevent softening and exposure of the dentinal tubules. In other words, this new layer is better than before.
Stannous fluoride vs sodium fluoride for sensitivity
In toothpaste form, stannous fluoride is superior to sodium fluoride in treating sensitivity. In fact, the sodium version of fluoride isn’t even known for reducing hypersensitivity at all. If it was, all sodium fluoride toothpastes would have “sensitive” on the label but it doesn’t.
In a randomized control trial, a 0.454% stannous fluoride toothpaste was compared to a sodium fluoride one. The results were that the stannous version of fluoride provided a clinically and statistically significant reduction in sensitivity.
- Another study found similar results as well in reduction of symptoms.
If you wanted further evidence of its efficacy, look no further than a study from the Journal of Clinical Dentistry. They found that stannous fluoride reduced thermal sensitivity by 68% and tactile sensitivity by 184% when compared to a NaF/Triclosan toothpaste.
Overall it appears that sodium fluoride is inferior to stannous at least in terms of being an anti-sensitivity agent.
Exception
Despite sodium fluoride not being effective at combating dentinal sensitivity in toothpaste, the varnish version of it tells a different story.
Fluoride varnish is basically a highly concentrated 5% sodium fluoride that is typically applied in-office at the dentist. This is in comparison to the vast majority of toothpastes which only contain 0.25% of it.
Studies have shown that fluoride varnish can provide anti-sensitivity effects that last up to 28 weeks. It does so by forming a calcium fluoride layer which plugs up all of the open dentinal tubules, which is a similar mechanism to stannous fluoride.
In case you were wondering why the varnish works in ameliorating sensitive teeth but the toothpaste version doesn’t is all due to the concentration. Apparently it requires close to 10,000 ppm of sodium fluoride for the calcium layer to form.
Potassium nitrate vs stannous fluoride for sensitivity
Both potassium nitrate and stannous fluoride have been proven to be effective for reducing teeth sensitivity. Studies have typically shown them to be somewhat equivalent in effectiveness. At least according to the studies that we can find, there isn’t one that is particularly “superior” over the other.
Aside from their efficacy, the major difference between them is in how they prevent and minimize hypersensitivity.
- Potassium nitrate does not occlude tubules but will desensitize the nerve directly from firing pain signals.
- Stannous fluoride directly occludes the tubules but does not desensitize the nerve directly.
Potassium nitrate (KNO3) contains a lot of potassium, which is used during the depolarization of generating an action potential in the nerve. The molecules move from an area of high concentration to low concentration when the nerve is stimulated.
- The sodium flows from outside the cell to inside the cell.
- Then the potassium flows from inside the cell to outside the cell.
Since the potassium nitrate supplies an overabundance of potassium to the outside of the cell, it prevents the normal sequence of events from occurring. The potassium is unable to flow out of the cell and thus the pain signal is prevented from firing.
In summary, their mechanism for desensitizing may differ but their efficacy have been shown to be equivalent. Feel free to give both products a try and see which one works better for you.
Additional read: Stannous fluoride vs Potassium nitrate
Takeaway
Stannous fluoride is good for sensitive teeth because it is effective as an anti-sensitivity agent. In addition to preventing tooth decay, it also possesses the ability to occlude open dentinal tubules and that is how it alleviates discomfort.
However for the desensitizing effect, you should expect to use it continuously long term. You must brush with it twice a day for two minutes each. If you stop using it, you will lose the desensitizing effect.
The reason is because as you eat acidic foods, they will eventually wear through the new smear plugs that are created by the toothpaste. You have to keep using it to replenish the clogging effect. It is almost like a life-time sentence but if you have sensitive teeth, you’ve just gotta do it!