Sensodyne is the go to toothpaste if you have sensitive teeth because as the name implies, it works for sensitivity. Sensodyne works by incorporating anti-sensitivity agents within their toothpaste to desensitize all of your teeth.

According to Sensodyne, the desensitization occurs by utilizing either potassium nitrate or stannous fluoride. Both of them will work by making your teeth less sensitive but they accomplish it in different ways.

However, what we want to bring your attention to is that their toothpastes will use only one or the other for desensitization. That means you will not find a product that contains both potassium nitrate and stannous fluoride. It will be either or only.

Sensodyne toothpastes contain stannous fluoride or potassium nitrate as anti-sensitivity agents that work by either creating a barrier over sensitive areas or by soothing the nerves inside your tooth. Sensodyne products contain fluoride, which helps fight against cavities, so you can maintain healthy teeth, every day.
Source

As long as you understand that, we will dive further into explaining how each of those two ingredients make your teeth less sensitive.

Table of Contents

How potassium nitrate desensitizes your teeth

It is not completely clear how potassium nitrate desensitizes your teeth but there are currently two theories on how it works. However, we believe that it is still the initial theory that is the most plausible.

Initial theory

The initial theory was that potassium nitrate prevented the nerve endings of the tooth from firing signals when exposed to stimuli.

It diffuses through the dentinal tubules to reach the nerve endings.
It supplies a large concentration of potassium ions to the extracellular matrix.
This new concentration gradient prevents the depolarization and repolarization of the nerve action potential from generating.

crest depolarization repolarization — Credit: Crest

Essentially molecules will diffuse from an area of high concentration to an area of low concentration. This is what is meant by diffusing across the concentration gradient.

The potassium nitrate supplies an over abundance of K+ and therefore disrupts the nerve from firing properly. This was the accepted theory for a long time. Quite a few research studies were supporting this because they couldn’t find evidence of potassium nitrate occluding the dentinal tubules.

Additional research saying that there were no tubule occluding effects.

New theory

There has been new studies which have been released which are suggesting that potassium nitrate can partially occlude the dentinal tubules. What that means is that in addition to preventing the nerves from firing, the physical blockage of the tubules will prevent stimuli from reaching the nerve.

Basically our teeth have pores which are normally occluded by smear plugs. That prevents stimuli from irritating our nerves. For patients experiencing a lot of sensitivity, those smear plugs may not be present, thus leaving the tubules wide open to stimulation.

What the potassium nitrate does is supposed to mimic what the plugs do and block off the tubules. According to one study, the it was able to partially occlude the dentinal tubules. Various other studies have also found evidence of it occluding them as well.

Why the second theory may not be as plausible

According to a study in the Compendium of Continuing Education in Dentistry, the potassium nitrate does not occlude tubules. The compared the patency or how open the tubules were for potassium nitrate toothpastes and potassium nitrate alone.

The toothpaste did form a residue layer while the potassium nitrate alone did not. Their theory was that, the residue layer was actually a result of the inactive ingredients such as the abrasives within the toothpaste which are occluding the tubules.

This study found that silica, which abrades stains were also responsible for occluding the tubules after brushing.
This study found that fume silica was even more effect than regular silica in tubular occlusion.

Taking into all of this evidence, we would have to say that the studies which did show occlusion or partial occlusion of tubules with potassium nitrate did not test it by itself. They always tested the tubules with a toothpaste containing potassium nitrate. The occlusions that they’re most likely seeing are due to the abrasives within the toothpaste and not from potassium nitrate itself.

Does it work?

Yes potassium nitrate does effectively desensitize your teeth so it definitely does work. In fact, there has been a study from the Journal of the American Dental Association from as early as 1974 which demonstrated the efficacy of potassium nitrate.

More recent studies have also showed it to be effective at desensitizing.

The researchers tested different concentrations of potassium nitrate from 1% all the way to 15%. What they found was that as they increased the concentration the desensitizing effect increased as well.

As a perk, they also discovered that it did not discolor the teeth. It was also not harmful to the gums nor the mouth. Overall it was considered very safe to use.

Studies have shown that there is no adverse effect on the pulp despite being able to diffuse to the nerve endings.

How stannous fluoride desensitizes your teeth

Stannous fluoride desensitizes your teeth by physically occluding the tubules that lead to the nerve. It does so by forming a tin-rich deposit over the surface of the tooth and consequently blocking off all the tubules.

You read that correctly, it occludes via a tin-rich deposit. It is precisely the same tin that you are thinking of because the molecular formula for stannous fluoride is actually SnF₂ which means it has one tin and two fluoride ions.

A study in the Journal of the American Dental Association (JADA) confirmed those findings. They found that stannous fluoride toothpastes effectively occluded the dentinal tubules with a deposit consisting of tin, zinc, phosphate, and silicon.

This may have been a surprise to you because you probably thought the fluoride was solely for preventing tooth decay. However, stannous fluoride has been proven to have the ability to desensitize your teeth.

Although you should be aware that there are multiple forms of fluoride that can come in toothpaste.

Stannous fluoride
Sodium fluoride
Sodium monofluorophosphate

Is it effective?

Stannous fluoride has been proven to be able to desensitize teeth. The first study found that a gel containing 0.4% SnF₂ did reduce sensitize albeit gradually over time. It required approximately consistent use over the course of 2-4 weeks to see any effects.

The JADA study found that a 0.454% stannous fluoride effectively coated dentin surfaces and occluded patent dentin tubules. It did take about 8 weeks for the desensitization to achieve a full effect.

However there is one particular downside to stannous fluoride and that it has the potential to cause teeth staining. Recent advances in abrasive systems within toothpaste have managed to reduce the stianing potential but the risk is still present.

Which one is more effective for sensitive teeth?

The effectiveness of both desensitizing agents were comparable according to the few studies that we found. A study in the Journal of Clinical Dentistry compared 7.5% calcium sodium phosphosilicate (NovaMin), 5% potassium nitrate, and 0.4% stannous fluoride.

After 12 weeks: the dentifrice containing NovaMin reduced sensitivity 87% and 91%, stannous fluoride gel 87% and 85%, and potassium nitrate dentifrice 84% and 79%.
All three were effective in reducing dentinal hypersensitivity.
The Novamin appears to have been the most effective.
Stannous fluoride seems to be slightly more effective than potassium nitrate.

However we would say that the results weren’t different by a wide margin. They were all still relatively comparable and definitely effective.

Comment: What we find incredibly interesting is that there are no products which utilize both potassium nitrate and stannous fluoride. All of the studies and tests compared them individually. Even sensodyne which is known for their products containing potassium nitrate, only used either or in their desensitizing toothpastes.

This leads us to believe that there may be a compatibility or stability issue when trying to formulate a toothpaste with both ingredients. Due to that you may have to just choose one over the other.

Takeaway

Surprisingly, sensodyne doesn’t solely use potassium nitrate as their desensitizing agent in their toothpastes. Some of their products have it while others utilize stannous fluoride.

It has been proven that both of these ingredients work in desensitizing your teeth. The stannous fluoride does so by occluding the dentinal tubules thus preventing stimuli from reaching the nerve. The potassium nitrate will prevent the tooth nerve from firing signals by making it unexcitable.

It is unclear which one is superior but both seem to work in reducing sensitivity. Our recommendation is to give both of them a try. Use one for 3 months and then switch to the other one for another 3 months. Depending on which one works better for you, we would stick with that one!

What is important is that, the Sensodyne Pronamel is a part of our armamentarium on how to stop sensitive teeth pain immediately. In other words, you should use it if you have sensitive teeth.

Last but not least, we just want to point out that ALL sensodyne products contain fluoride. Therefore if you were looking for a fluoride-free version of it, you may need to check out a different brand.

How Does Sensodyne Work?