Desensitizing Toothpastes – Stannous Fluoride vs Potassium Nitrate

Stannous fluoride and potassium nitrate are two common desensitizing agents used in toothpastes. They are effective in reducing dentinal hypersensitivity but the mechanism by how they do it differ.

Are you curious as to how to works and which one would be better for you?

We’re going to do a deep dive into the mechanism for how both of these sensitive toothpastes work along with any additional effects they may have. Then we’ll get you our opinion as to which one is more effective!

Stannous fluoride vs Potassium nitrate for desensitizing teeth

Both of these desensitizers are commonly found in sensitive toothpastes but they work differently. Sensodyne actually uses both but only one or the other in their products. They never use both together so it is always either or.

The mechanism via how they stop sensitivity is also different:

• Stannous fluoride desensitizes your teeth by occluding open dentinal tubules.
• Potassium nitrate desensitizes your teeth by rendering the nerve unexcitable.

Knowing which anti-sensitivity agent you’re using is important because some individuals may find that a particular one works best for them. Therefore you shouldn’t think that all “sensitive” toothpastes are the same because they’re not. It may be worthwhile to explore the different desensitizers to find the optimal dentifrice that works for you.

How does stannous fluoride desensitize teeth?

Stannous fluoride reduces sensitivity by occluding open dentinal tubules. Typically having open dentinal tubules are more sensitive than having them closed.

Under normal circumstances, individuals with no sensitivity will have the vast majority of their tubules closed off. They are usually blocked or clogged with smear plugs.

The smear plugs prevent stimulus from interacting with the fluids inside of the dentinal tubules. Essentially what happens is that the nerve endings are unable to detect stimuli since there is barrier between them.

Individuals with a lot of sensitivity will often be missing smear plugs or have enlarged ones. Having the dentinal tubules wide open means that stimuli can directly enter and cause havoc. In other words, the nerve endings are open to experiencing all stimuli that it gets exposed to.

How stannous fluoride desensitizes the teeth is by plugging all of the tubules and thus protects the tooth from stimuli. This happens by brushing with it on a daily basis twice a day and it recreates the smear layer. This new smear layer is formed from the tin in SnF₂ which interacts with other molecules to form a deposit of zinc, phosphate, and silicon.

Summary: People with sensitivity often have missing smear plugs so their dentinal tubules are open to stimulation. The stannous in fluoride will interact with other molecules to form a deposit that acts as a new smear plug. Essentially it creates a physical barrier against stimuli.

Is stannous fluoride harmful?

The only major adverse effect from stannous fluoride is its potential to stain teeth.

• A study in 1982 first reported a yellow-golden stain on teeth from using stannous fluoride.
• The FDA also lists teeth staining as a potential side effect.

The staining occurs when the stannous reacts with sulfhydryl groups in the mouth to form stannic sulfides. The sulfur in the mouth comes from the bacteria which naturally inhabit the oral cavity.

Nonetheless this adverse effect is merely cosmetic and is not harmful to your body. Although there has been recent advances in new technology where toothpaste makers have reduced the staining from stannous fluoride.

How does potassium nitrate desensitize teeth?

Potassium nitrate reduces sensitivity by rendering the tooth nerve unexcitable. Studies have found that there was a rapid relief of sensitivity after 2 weeks of use. Symptoms continued to further improve with continued use over 12 weeks.

The mechanism with how potassium nitrate (KNO₃) works is by supplying an overabundance of potassium ions (K⁺) to the nerve. This excessive amount of potassium interferes with the natural concentration gradient of K⁺ around the nerve endings.

Under normal circumstances there is more potassium inside the cell than outside. When a stimulus occurs, molecules flow from an area of high concentration towards a low one.

Since the potassium nitrate toothpaste provides an excessive amount of potassium, it reverses the natural concentration gradient. It effectively prevents the K+ from flowing outwards since there is too much of it now. The end result is the nerve being rendered unable to general an action potential thus no sensitivity will be felt.

Is potassium nitrate harmful in toothpaste?

Potassium nitrate is commonly found in many toothpastes that are used for sensitive teeth. According to Crest, numerous regulatory boards consider its use to be safe and effective for decreasing sensitivity. The FDA first approved its use for toothpastes back in 1991. At the time, it was the only approved desensitizer for teeth.

In case you were worried, brushing with it does not permanently leave it inside of your tooth. The ingredient will naturally dissipate over time because for you to sustain the desensitizing effect you need to continue using it. That is the only way to maintain the concentration needed for sensitivity reduction.

According to Sensodyne, the sensitivity may return once you stop using the product.

Potassium nitrate vs Stannous fluoride – other effects

Unfortunately potassium nitrate is used purely for tooth desensitization. It has no other effects aside from alleviating discomfort from sensitivity.

Stannous fluoride on the other hand does have anti-plaque and cavity prevention.

• It does contain fluoride and we all know that fluoride fights cavities!
• Studies have shown that stannous fluoride can reduce dental calculus build-up, dental plaque, gingivitis, stain and halitosis.

In fact there has even been research that stannous fluoride was superior to sodium fluoride in terms of gingivitis, plaque, and gingival bleeding reduction.

Ultimately potassium nitrate has only one effect while the stannous fluoride has multiple.

Which is better stannous fluoride or potassium nitrate?

In terms of desensitizing teeth, both products are equally effective in alleviating symptoms. Although in terms of cavity prevention and plaque inhibition, stannous fluoride comes out ahead. The reason is due to the fact that potassium nitrate only desensitizes and does nothing else for your teeth.

Both potassium nitrate and stannous fluoride are effective in reducing dentinal hypersensitivity. Studies have shown that they do work and that the results were comparable.

• Stannous fluoride reduced sensitivity by 87% and 85%
• Potassium nitrate reduced sensitivity by 84% and 79%

Unfortunately there are no additional effects from using KNO₃ so we’ll have to say that stannous fluoride is better.

Although the vast majority of potassium nitrate toothpastes do tend to have sodium fluoride within it. This equalizes the cavity prevention aspect for both toothpastes.

However studies have shown that stannous fluoride is superior to sodium fluoride in gum health. There was often a greater reduction in periodontal symptoms with stannous over sodium fluoride.

Is there a toothpaste with both stannous fluoride and potassium nitrate?

To our knowledge, there isn’t any toothpaste that contains both stannous fluoride and potassium nitrate together. From our previous research in our other article about how Sensodyne works, we discovered that some of their products only used one or the other. However they never combined both of the desensitizing agents together.

There was absolutely no mention on Sensodyne’s website as to WHY both desensitizing agents couldn’t be used together. They desensitize the teeth via completely different mechanisms so they shouldn’t interfere with one another. Google search yielded no relevant results either.

We came to an inconclusive conjecture that the two substances were probably incompatible or that they’re not stable together. Maybe the toothpaste falls apart or they inactivate one another.

Stannous nitrate is a novelty explosive

After another round of deeper research, we came across some information from Sciencemadness which suggested that stannous nitrate was an “obscure novelty explosive”.

Basic stannous nitrate, with the formula Sn3(OH)4(NO3)2, is a white crystalline substance which is slowly oxidized upon exposure to air, and partially decomposes in pH nuetral water. It is a high explosive, detonating when strongly rubbed, hit with a hammer, or heated above 100 °C. Thermal decomposition proceeds at 125 °C, resulting in formation of SnO2, nitric oxide, and water.

The salt may result when elemental tin (Sn) foil (not common aluminum foil) is reacted with a solution of copper nitrate to form a precipitate that is a sensitive explosive when dried. When detonated with heat or friction, it gives off sparks. It can also be made by using cold, very dilute nitric acid to dissolve tin, then adding some sodium carbonate (baking soda might work instead), but not enough sodium carbonate to cause to cause the expected precipitation of stannous (tin II) carbonate.

Solutions of tin(II) sulfate can be formed by reaction of copper(II) sulfate with metallic tin. The tin(II) sulfate then reacts with sodium carbonate to form tin(II) carbonate (ammonia could probably be used instead, I do not think ammonia solubilizes tin precipitates like it does with some other transition metals). The SnCO3 precipitates out as a solid from the solution. The solid tin carbonate, SnCO3, reacts with dilute nitric acid to form solutions of Sn(NO3)2, which are reasonably stable. However, attempting to evaporate the solutions to dryness results in decomposition, which can in some instances be violent. The decomposition products are mainly SnO2, nitrous oxide, and hydroxylamine, with other oxides of nitrogen also produced.

– Andershoveland

The explanation above does seem reasonable in that it combined the stannous from stannous fluoride with the nitrate from potassium nitrate. The end result is stannous nitrate which can be combustible.

We tried to find further evidence in support of it but it really is quite difficult to come across information about it at all.

Stannous fluoride (SN₂) is basically tin fluoride so stannous is just another name for tin. According to the NJ health website, tin is listed as “not compatible” with nitrates. In a MSDS, tin does have a specialty fire hazard remark when reacted with nitrates.

In conclusion there is no toothpaste with both stannous fluoride and potassium nitrate because the formation of stannous nitrate is a potential combustible. After all, don’t forget that potassium nitrate is used to make gunpowder and it is also known as saltpeter.

Summary

Stannous fluoride and potassium nitrate are both effective at reducing teeth sensitivity but they do so via different mechanisms. The amount of sensitivity relief does not appear to be statistically significant from one another so you may feel free to use either.

However where potassium nitrate loses out is in the fact that it only desensitizes with no other effects. The stannous fluoride does have the edge in that it can reduce cavities as well as plaque and tartar build up.