You might be surprised that a dentist deals with sensitive teeth. I’ve had them for decades.
The Sensodyne formulas I used did help, but I don’t use them anymore.
Sensodyne has become shorthand for sensitivity toothpaste, and its classic formulas work by calming the nerve. But sensitivity is a signal that the softer layer under your enamel is exposed. Calming the nerve is like pulling the battery out of a smoke alarm. The noise stops, but the fire is still burning.
I’d rather put the fire out. I switched to a nano-hydroxyapatite toothpaste, which helps seal the exposed spots that let cold reach the nerve. For me, relief came faster and lasted longer. Then I find out what started the fire, so it doesn’t start again.
Why do teeth get sensitive?
That ache from cold water means dentin, the layer under your enamel, is exposed. Dentin is filled with microscopic tubules that run toward the nerve. Cold, heat, or sugar moves the fluid inside those tubules, and the nerve registers that movement as sharp pain.
Five causes account for most exposed dentin:
- Aggressive brushing
- Worn toothbrush bristles
- Gum recession
- Acidic drinks
- Grinding or clenching
Aggressive brushing is the easiest cause to check and fix. Look at your toothbrush: if the bristles are splayed after three weeks, you’re pressing too hard. Switch to a soft or extra-soft brush and use small, gentle circles at the gumline.
Worn bristles do damage even with a light touch. Once they fray, their tips turn sharp and scrape the gumline. Replacing the head every four weeks keeps them soft.
Recession shows up at the gumline. An exposed root is darker than the enamel above it and is often notched where the tooth meets the gum. Gentler brushing protects it, and so does cleaning between your teeth every night, since gum inflammation is the other major driver of recession.
Acidic drinks like sparkling water, soda, kombucha, wine, and anything with apple cider vinegar pull minerals out of enamel each time they wash over your teeth. Drinking them less often cuts the number of acid exposures.
Grinding is harder to catch because it happens during sleep. It’s often linked to sleep-disordered breathing, so if you snore, wake up tired, or wake with a dry mouth, get your breathing evaluated.
At your next dental visit, ask three questions:
- Is the dentin exposed by recession or by wear? The answer tells you whether to focus on your gums or your enamel.
- What do you think is causing it? Brushing technique, diet, and grinding each call for a different fix.
- Do you see signs of grinding? Your dentist can spot wear patterns you can’t see in a mirror.
Pain that lingers after the cold is gone, or pain when you bite down, is a different problem. Either one can signal a cavity or a cracked tooth, so see your dentist promptly.
Finding and fixing the cause takes time. In the meantime, you still want the pain to stop.
How does Sensodyne work?
Sensitivity toothpastes take one of two approaches: calm the nerve or seal the tubules. Sensodyne uses both, depending on the formula, so the tube you pick matters.
The classic formulas, like Sensodyne Fresh Mint, use 5 percent potassium nitrate. Potassium builds up around the nerve and makes it less likely to fire. That’s the smoke alarm battery.
Rapid Relief, Sensitivity & Gum, and the U.S. version of Repair & Protect use stannous fluoride instead. Stannous fluoride forms a layer over exposed dentin that seals the tubules.
Sealing makes more sense to me, but stannous fluoride comes with trade-offs. For decades it stained teeth, left a metallic taste, and broke down in the tube. Newer stabilized formulas have reduced those problems. Nano-hydroxyapatite seals the tubules too, and it does so without fluoride.
Is hydroxyapatite good for sensitive teeth?
Nano-hydroxyapatite is biomimetic: it’s designed to closely match hydroxyapatite, the mineral that makes up about 97 percent of your enamel and roughly 70 percent of your dentin. That close match lets it supply mineral to replace what acid dissolves away.
At tens of nanometers across, nano-hydroxyapatite is small enough to enter exposed tubules and bond to the dentin, sealing them so cold can’t reach the nerve. It also bonds to enamel in the microscopic gaps acid leaves behind, which is the remineralizing job fluoride does in a regular toothpaste.
The clinical evidence supports it. A 2023 meta-analysis of 44 clinical trials found hydroxyapatite reduced sensitivity 23 percent more than fluoride, a statistically significant difference. Against the desensitizing ingredients in sensitivity toothpastes, it performed at least as well, with a slight edge that wasn’t statistically significant. Two of the three authors work for a company that makes hydroxyapatite toothpaste, which you should know when reading the results.
Those trials measure how much sensitivity drops. If you live with sensitive teeth, two other questions matter as much: how soon relief comes, and what happens when you stop.
How fast does sensitivity toothpaste work?
Potassium nitrate is the slowest. Potassium has to build up around the nerve, so full relief typically takes two to four weeks of twice-daily brushing. That matches what I lived with: Sensodyne helped, but meaningful relief took about two weeks.
Sealing ingredients can work faster because they act directly on the exposed dentin. Sensodyne says Rapid Relief starts working within three days of twice-daily brushing. Nano-hydroxyapatite can start sooner. In one small trial, a 1 percent nano-hydroxyapatite toothpaste measurably reduced sensitivity five minutes after a single application, and relief kept improving over four weeks.
What happens after you stop is where the research is thinnest, because few studies follow people once they put the tube down. Potassium nitrate works only as long as potassium keeps reaching the nerve. When I stopped using Sensodyne, my sensitivity could come back within days or weeks, and I’d have to build the benefit up again. A seal on the dentin can outlast your last brushing, but acid and brushing wear it down, and research hasn’t established how long it holds in a real mouth.
My switch to nano-hydroxyapatite went differently. I noticed improvement within days, and the relief seemed to last. Over the years, I’ve heard the same from many thousands of people. Some tell me their relief held for months, or longer, after they stopped. Those are personal accounts, not a clinical finding, and they can’t predict how long relief will last for any one person.
The rest of the tube matters too. Every Sensodyne formula contains fluoride, and several also contain sodium saccharin. Over time, I became more interested in fluoride-free options and more concerned about how some conventional toothpaste ingredients might affect the oral microbiome. A nano-hydroxyapatite toothpaste can cover sensitivity and remineralization without fluoride or foaming agents.
If you want relief that comes on quickly and holds, nano-hydroxyapatite is what I’d choose.
Why don’t more dentists recommend hydroxyapatite toothpaste?
The main reason is regulatory. In the U.S., the Food and Drug Administration (FDA) reserves cavity-prevention claims for fluoride toothpastes, so a nano-hydroxyapatite toothpaste is sold as a cosmetic and can’t print “anticavity” on the tube. That keeps it out of most mainstream brands. Japan took a different path: there, hydroxyapatite toothpaste is recognized as an anticavity product and has been a mainstream choice for decades.
Training plays a role too. Dental schools still teach fluoride as the standard, so many dentists stay with what they know. None of that changes what nano-hydroxyapatite does on your teeth.
What are the downsides of hydroxyapatite toothpaste?
The biggest one is that quality varies. Particle size, shape, and purity matter as much as the percentage on the label. The particles have to be small enough to bond to your teeth, and more isn’t automatically better: too much nano-hydroxyapatite can clump, which reduces how well it bonds.
Shape matters for safety. Europe’s Scientific Committee on Consumer Safety (SCCS) has evaluated nano-hydroxyapatite made of uncoated, rod-shaped particles and considers it safe in toothpaste. Its opinions don’t cover needle-shaped particles. To my knowledge, the only supplier whose nano-hydroxyapatite matches what the SCCS evaluated is Fluidinova, a European manufacturer that sells it as nanoXIM.
So I look for Fluidinova’s nano-hydroxyapatite at 2 to 5 percent. Most labels list only “hydroxyapatite,” so check the brand’s website, or email the company and ask who supplies its nano-hydroxyapatite and at what concentration.
Abrasiveness matters too, whatever toothpaste you use. Exposed dentin wears faster than enamel. Look up your toothpaste’s RDA (Relative Dentin Abrasivity) score. Under 50 is considered very low.
When a tooth needs more
A tooth that stays sensitive, even with the right toothpaste, needs a more concentrated dose of nano-hydroxyapatite. A varnish provides that. It’s a leave-on treatment originally formulated for dentists to apply in the office, and it stays on the teeth longer than toothpaste, which gives the nano-hydroxyapatite more time to seal exposed dentin.
I apply it in trays and wear them for an hour. First I brush, floss, and scrape my tongue, so the varnish reaches clean tooth surfaces. I notice less sensitivity over time, and sometimes after a single use.
Varnish supplements daily toothpaste rather than replacing it. You use it daily until the sensitivity resolves, then a few times a week to maintain the results. I apply it a few nights a week, and any time my teeth start to feel sensitive. It helps most on exposed roots. Without enamel to protect them, roots are softer and decay faster, so the varnish strengthens them as the sensitivity fades.
The toothpaste and the varnish I use are both Fygg’s. Fygg is my company, and I formulated them for exactly this job. The toothpaste uses Fluidinova’s nano-hydroxyapatite at 3.1 percent.
If you’ve used Sensodyne, nano-hydroxyapatite, or both, hit reply and tell me how fast relief came and whether it lasted when you stopped.
You’ve got this,
Mark
P.S. If one tooth has been sensitive for weeks, book a dental visit. Toothpaste and varnish can relieve the pain, but only finding the cause protects the tooth.
P.P.S. If you’re wondering what my oral care routine looks like, here it is: This toothpaste, this mouthwash alternative , this tongue scraper , this throat spray , these enzymes with meals, this Vitamin D3/K2, this CoQ10, this magnesium , this zinc , and these electrolytes.
Citations:
Anand, S., Rejula, F., Sam Joseph, V.G., Christaline, R., Nair, M.G., & Dinakaran, S. (2017). “Comparative Evaluation of Effect of Nano-hydroxyapatite and 8% Arginine Containing Toothpastes in Managing Dentin Hypersensitivity: Double Blind Randomized Clinical Trial.” Acta Medica (Hradec Králové), 60(3), 114–119. https://doi.org/10.14712/18059694.2018.3
Limeback, H., Enax, J., & Meyer, F. (2023). “Clinical evidence of biomimetic hydroxyapatite in oral care products for reducing dentin hypersensitivity: an updated systematic review and meta-analysis.” Biomimetics, 8(1), 23. https://doi.org/10.3390/biomimetics8010023
“Effect of desensitizing toothpastes on dentine hypersensitivity: A systematic review and meta-analysis.” (2018). Journal of Dentistry, 75, 12–21. https://doi.org/10.1016/j.jdent.2018.05.012
Dentalcare.com. “Dentinal Hypersensitivity: A Review: Over-the-Counter Products.” Course CE200. https://www.dentalcare.com/en-us/ce-courses/ce200/over-the-counter-products
Seong, J., Newcombe, R.G., Foskett, H.L., Davies, M., & West, N.X. (2021). “A randomised controlled trial to compare the efficacy of an aluminium lactate/potassium nitrate/hydroxylapatite toothpaste with a control toothpaste for the prevention of dentine hypersensitivity.” Journal of Dentistry, 108, 103619. https://doi.org/10.1016/j.jdent.2021.103619
Sharma, S., Shetty, N.J., & Uppoor, A. (2012). “Evaluation of the clinical efficacy of potassium nitrate desensitizing mouthwash and a toothpaste in the treatment of dentinal hypersensitivity.” Journal of Clinical and Experimental Dentistry. https://doi.org/10.4317/jced.50665
Scientific Committee on Consumer Safety (2023). “Opinion on Hydroxyapatite (nano).” SCCS/1648/22. https://health.ec.europa.eu/publications/hydroxyapatite-nano-0_et
Sensodyne. “What are the active ingredients in Sensodyne toothpaste?” https://www.sensodyne.com/en-us/about-sensodyne/ingredients/
Things I would NEVER let my kids do