How Does Sensitive Toothpaste Desensitize Teeth

There is an entire aisle of toothpastes at the pharmacy with a dizzying array of variety. So, what exactly makes a toothpaste desensitizing and how does brushing with it alleviate sensitivity?

You’re at the right place because we’re going to break it all down for you including how sensitive toothpaste works. Before we start, it helps to understand the mechanism with how teeth feel sensitivity because the toothpastes work to block that process.

How do teeth feel sensitive?

Absent of any tooth decay or infection, teeth can be sensitive from unclogged dentinal tubules. The mechanism for why we feel discomfort can be explained by Branstrom’s theory of dentinal hypersensitivity.

The theory states that receptors can elicit pain signals when they sense fluid movement within dentinal tubules. Different stimuli will either pull fluids away from the nerve or push it towards the pulp.

• Away from the pulp – Cooling, drying, evaporation, and hypertonic solutions
• Towards the pulp – Heating and probing

Under normal circumstances, the fluid movements are minimized due to the presence of smear plugs. These plugs naturally occlude the dentinal tubules, thus effectively minimizing stimuli from interacting with the fluids inside. Smear plugs serve as our body’s natural barrier against outside elements, protecting our quality of life.

However those who experience chronic teeth sensitivity will often have missing smear plugs or enlarged dentinal orifices. In other words all stimuli will trigger an exaggerated response.

Other reasons for teeth to be sensitive

The scenario above describes individuals who experience symptoms from gum recession or otherwise healthy teeth.

Although there are other ways for teeth to feel symptomatic.

• Tooth decay. Cavities are literal holes and having them in your teeth mean that you have a hole in your tooth. This hole is an open passage for all stimuli to enter, thus will be uncomfortable.
• Infection. The most common reason for hot and cold sensitivity is if the nerve is unhealthy. Extreme pain from temperature usually indicates a root canal is needed.
• Defective restorations. A cracked filling or broken one will leave your tooth exposed. Exposed tooth structure that is not covered nor protected can be prone to sensitivity.
• Fractured teeth. A broken tooth is certainly unhealthy and if sensitivity is all that you’re feeling, you should consider yourself lucky. Excruciating pain is actually the norm!

If your teeth are sensitive from any of the above conditions, brushing with anti-sensitivity toothpaste won’t help at all. All of these require treatment from a dental professional such as cavity fillings, root canals, extractions, and etc.

Please schedule a consultation with your dentist as promptly as possible.

How does sensitive toothpaste work?

What separates sensitive toothpaste from whitening ones is the inclusion of desensitizing agents in their formulation. Sensitive toothpastes work because they contain desensitizing agents. That singular ingredient is what makes it an anti-sensitivity toothpaste. Without it, it would just be any regular old toothpaste.

Different types of desensitizing agents in toothpaste:

• Potassium Nitrate
• Stannous Fluoride
• Nano-hydroxyapatite
• Strontium chloride
• Arginine

It is important to understand the differences between all of these desensitizers because they can work differently. If one doesn’t give you the relief that you’re looking for you may want to try a different one.

Without further ado, let’s dive into all of these different types of desensitizing agents in your toothpaste and how they work.

Potassium Nitrate

Potassium nitrate (KNO₃) otherwise known as saltpeter renders the tooth nerve unexcitable when it builds up to a sufficient concentration.

Examples of KNO₃ toothpastes:

• Sensodyne pronamel
• Colgate sensitive original
• Hello sensitivity relief

Potassium nitrate works by flooding the tooth nerve with potassium ions. The overabundance of potassium reverses the concentration gradient, thus preventing an action potential from firing. The ultimate result is no sensitivity signal gets sent from your nerve.

The key point we wish to emphasize is that the desensitizing effect occurs only when there is a sufficient concentration of potassium. You have to continually brush with this toothpaste for it to slowly build up the concentration. According to the makers of Sensodyne, it takes about two weeks for the effects to show.

Mechanism for action potential generation

Under normal circumstances, there is a natural concentration gradient of potassium and sodium. All molecules move down the gradient from a higher concentration towards a lower one. It never moves in the reverse direction.

Upon a stimulus, the sodium rushes into the cell which depolarizes the cell. Then potassium rushes outside and it repolarizes the cell. Effectively an action potential is generated, which means the sensitivity signal gets sent to our brain.

What potassium nitrate does is reverse the gradient by making the extracellular concentration of potassium higher than intracellularly. This prevents the cell from repolarizing since the potassium can’t flow out. Thus, the nerve cell is unable to complete all of the required steps to make you feel uncomfortable.

Stannous fluoride

Stannous fluoride (SnF₂) occludes patent dentinal tubules thus effectively preventing stimuli from interacting with the fluids.

Examples of SnF₂ toothpastes:

• Colgate total
• Crest pro-health
• Sensodyne rapid relief

Essentially stannous fluoride works by recreating the missing smear plugs and reclog all of the open tubules. With the orifices closed and blocked off, less of the stimuli will be able to interact with the components within the tubules.

Basically the tooth nerve will be shielded from all external stimuli. It is akin to having a protective barrier that shields you.

Mechanism for SnF₂ tubule occlusion

Stannous fluoride is a form of fluoride that is stabilized by Tin (Sn). The desensitizing effect is actually purely derived from the tin and not from fluoride. Are you surprised?

A study from the Journal of the American Dental Association, found that stannous fluoride toothpaste significantly reduced hypersensitivity after 8 weeks.

•  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%.

In summary, the newly created smear plugs were a tin mixture composed of zinc, phosphate and silicon. This metallic complex possesses the ability to occlude the tubules.

In case you were curious, we’ve written an article comparing stannous fluoride vs potassium nitrate. Which one is superior in providing sensitivity relief? Read to find out more.

Nano-hydroxyapatite

Nanohydroxyapatite (nHap) will desensitize teeth by occluding open dentinal tubules, which makes it work in a similar way to stannous fluoride.

Examples of nHap toothpaste:

• Davids sensitive & whitening toothpaste
• Risewell mineral toothpaste
• Dr Jen super paste

Essentially nano-hydroxyapatite toothpastes work by directly clogging all of the orifices of open dentinal tubules. By occluding the orifices it prevents external stimuli from interacting with the tubular components. Since there is no interaction, no nerve signals are fired.

Studies have shown that it is effective enough to reduce teeth sensitivity after whitening sessions. We all know that the teeth become extremely sensitive after bleaching and if it works for that it will work for your everyday symptoms.

Mechanism for hydroxyapatite tubule occlusion

The nano-hydroxyapatite is a smaller version of the very same tooth mineral that your enamel is made of, hence the “nano” in front of the name. Since they’re identitcal substances, the nHap simply inserts itself into all of the tubules’ orifices.

Therefore instead of having smear plugs, the hydroxyapatite will serve as a replacement. This is even better because its similar to having extra enamel.

The tubular occlusion from nHap is even more effective than stannous fluoride because it can continue to form an additional layer over the entire enamel surface. This extra protective barrier further shields the tooth from sensitivity.

Another difference between hydroxyapatite and SnF₂ is that the Tin needs to form a complex in order to plug the tubules. The nHap can directly insert itself without the need of other substances in the mouth.

Strontium chloride

Strontium chloride is yet another dentinal occlusion desensitizing agent. Studies have shown it to be effective in reducing sensitivity.

We would love to give you examples of brands that use strontium chloride but unfortunately we couldn’t really find any. As far as we know, there is no toothpaste that is available in the United States that has it in its formulation.

Historically, it was present in the original Sensodyne toothpaste back in 1961. However according to the timeline on their website, strontium chloride seems to have been mostly replaced by potassium nitrate by the 1980s.

We browsed through every product offering from Sensodyne but to no avail. There isn’t a single product line that still uses strontium chloride.

We are unsure why it was discontinued because the studies did show that it was effective in reducing sensitivity. Perhaps the potassium nitrate was just a superior product?

Arginine

Arginine based toothpastes will reduce teeth sensitivity by occluding open dentinal tubules. Therefore it works in a similar manner as stannous fluoride, nanohydroxyapatite, and strontium chloride.

The only toothpaste that we are aware of that uses arginine is Colgate pro-relief but they call it Pro-Argin. This toothpaste is actually NOT available in the United States. It is currently only available for purchase overseas such as in Europe and Asia. Historically, it used to be available in the US but for some reason they ceased distribution here.

We’ve inquired with Colgate before and they didn’t give us a reply. They merely said that they’ll pass on the message that we liked their product. We use to recommend it because it worked really well in reducing sensitivity so we’re not sure why distribution stopped.

Can you use this type of toothpaste everyday?

Sensitive toothpaste is meant to be used every single day for the rest of your life.

Brush teeth thoroughly for at least 1 minute twice a day (morning and evening), and not more than 3 times a day, or as recommended by a dentist or doctor. Make sure to brush all sensitive areas of the teeth. Minimize swallowing. Spit out after brushing.

Sensodyne Instructions

The reason is because brushing with it does not permanently cure teeth sensitivity. The toothpaste can only help you manage the symptoms. According to Sensodyne, once you stop using it the effects will cease and the sensitivity will return.

We are unsure about why Sensodyne is even stating that you should brush for at least 1 minute. The general consensus is to brush for at least 2 minutes twice a day and that is according to the ADA.

Should you rinse after using sensitivity toothpaste?

You can rinse afterwards if you want to because you want to minimize the chances of you swallowing it. The label specifically say you should call for medical help or poison control if you swallow it! In order to decrease the chances of that happening, it is typically better to rinse out after you finish brushing.

With that being said, if you only spit out and you don’t rinse, it actually allows the toothpaste to be more effective. The reason is because the toothpaste desensitizing effect works topically. That means the longer it stays in contact with your teeth the more effective it’ll be.

That is actually a tip for increasing the efficacy of the desensitizing effect. Often times if you think the sensitive toothpaste isn’t working, it is probably because you haven’t left it on your teeth for long enough.

How long does it take for tooth sensitivity toothpaste to work?

Depending on which desensitizing agent is in the particular sensitive toothpaste that you’re using, the relief may be immediate or it could take 2 weeks. On average these toothpastes take 1-14 days for it to starting alleviating the symptoms.

• Potassium nitrate – Studies have shown that it may take up to 2 weeks for you to see results. The symptoms continued to improve up to the 12 week mark.
• Stannous fluoride – Studies have shown that a desensitizing effect was present after a single day of use.
• Nano-hydroxyapatite – Studies have shown that symptoms were reduced after using for a day.

Based on the data above, the tubular occlusion desensitizers such as stannous fluoride and nanohydroxyapatite can work as fast as 1 day. The nerve desensitizer, potassium nitrate will take longer to work because it may take about 2 weeks for it to show an effect.

Nonetheless, that is just the time it takes for the toothpastes to start working.

Takeaway

Depending on the desensitizing agent in the sensitive toothpaste, the mechanism via how it works will be different. Basically these toothpastes can be divided into two categories. They either reduce sensitivity by tubular occlusion or desensitizing the nerve. Both of them will work but perhaps one works better for you than the other.

It is important for you to know exactly how your toothpaste works because if your product is not working, you should try the other one. Therefore you should read the label carefully to know exactly how it works!