I was in Los Angeles last week visiting one of my daughters, and she took me to Erewhon. (Happily, for the record.)
If you’ve never been, Erewhon is the grocery store where a smoothie costs $22 and the parking lot looks like a Tesla dealership. When in Rome, right?
So, of course, I end up in the toothpaste aisle, and what I saw was pretty exciting. Nano-hydroxyapatite was everywhere. Brand after brand, all featuring nHAP—the calcium mineral that makes up 97% of your enamel.
Ten years ago, you couldn’t find this stuff outside of Japan. Now it dominates the toothpaste aisle at the most talked-about grocery store in LA. That’s real progress!
For years, I told patients who asked me about toothpaste that everything on the market was a compromise. Boka was the best option available for a while—and I used to recommend them. They got nHAP into people’s hands when nobody else was doing it.
A woman next to me in the aisle picked up a tube of Boka and said, “Do you know anything about these?”
I told her I might know a thing or two.
We got to talking. She’d heard about nHAP from a podcast. She was choosing a toothpaste based on the one ingredient she’d heard of, but neglecting to consider everything else on the label.
I picked up the tube of Boka she was holding and flipped it around…
Various essential oils: peppermint, spearmint, wintergreen, anise, plus cardamom oil, and menthol. Seven ingredients with broad-spectrum antimicrobial activity, doing the same thing: killing bacteria.
Sodium Lauroyl Sarcosinate, which is a misleading one. The front of the tube advertises “SLS Free” but what they did was swap SLS for a surfactant cousin. Different chemical name, same category of ingredient, same foaming-and-stripping effect on the cells the bacteria in your mouth depend on. It’s a softer version, but it’s still a surfactant! “SLS Free” has become a marketing phrase. It’s not the same as surfactant-free.
She said, “Aren’t essential oils natural?”
Natural, maybe. Microbiome-destructive, definitely.
Here’s the thing about “natural.” A small bottle of tea tree oil is the concentrated extract of pounds of leaves. Nobody is putting that much tea tree into their mouth by chewing leaves in real life. Concentrate any plant compound enough and it stops behaving like a plant and can behave like a drug.
I started flipping every tube on that shelf. All the same story…
Essential oils in every single one. Some had four. One had nine, including tea tree oil, one of the most potent broad-spectrum antimicrobials in nature. These are small companies doing good work getting nHAP into people’s hands. But they’re loading their formulas with ingredients that don’t discriminate in the bacteria that they kill and suppress.
Here’s what I think is actually happening. Toothpaste is regulated as a cosmetic in the U.S. (even though it really shouldn’t be). So these brands are borrowing from the skincare playbook. Chamomile. Lavender. Exotic botanicals. “Elevated” ingredients that signal sophistication and justify premium pricing.
It’s cosmetic mimicry. And it works, because we’ve been trained to read toothpaste labels the way we read skincare labels. But having chamomile in your toothpaste isn’t the upgrade the label wants you to think it is.
Here’s what I told her…
There is no remineralization without the oral microbiome.
Your teeth cannot heal without the bacteria in your mouth.
Damage the microbiome, and remineralization slows or even stops.
The “good guys” aka the commensal, or beneficial, bacteria in your mouth—species like S. sanguinis, S. salivarius, S. oralis—are part of a microbial community that produces nitric oxide, which supports cardiovascular health. They communicate with your gut and your brain through what researchers now call the oral-gut-brain axis. They keep bad breath in check. They stabilize your saliva chemistry so calcium and phosphate can redeposit onto weakened enamel.
When your toothpaste wipes them out, you’re not just risking your teeth. You’re knocking out bacteria that keep your entire body healthy.
It’s like watering a garden while pouring salt on the soil.
A 2021 study published in Antibiotics tested essential oils — including thyme and oregano — against both cavity-causing species like Streptococcus mutans and beneficial commensals like Streptococcus sanguinis. The essential oils killed both. The researchers put it plainly: these effects on commensal bacteria “can raise concerns,” because eradicating them means “an imbalance can occur leading to infection or oral disease, turning our solution into a problem.”
I don’t blame these companies. Essential oils taste good and give toothpaste that tingly clean feeling. For a long time, we didn’t understand the oral microbiome well enough to know this was a problem. But now we do.
At this point, my new friend in the toothpaste aisle asked another question: “OK, so I need nHAP without the essential oils. But isn’t 10% the concentration to look for? Isn’t more better?”
Great question. And the answer surprised her.
That 10% number traces back to a single 2009 study out of China. The “nano” particles they tested were 500 to 2,000 nanometers, which, by today’s standards, aren’t nano at all.
They’re micro-particles. Ten to forty times larger than what nano actually means now.
Of course you needed 10% of that. You need a lot of gravel to fill a hairline crack. But engineer a fine-grain sand that fits the crack exactly, and you need far less.
But efficacy isn’t the only question worth asking about a toothpaste. And this is where we dentists tend to get narrow-minded…
We tend focus on what’s happening to tooth structure. Does this rebuild enamel? Does it whiten teeth?
But a toothpaste ingredient doesn’t stay on your teeth. It touches your gums. It gets absorbed through the thin tissue of your mouth. It ends up swallowed accidentally. It ends up in your gut. The right question isn’t just “does it work on my teeth?” It’s also “is it safe for my whole body?”
That’s where the SCCS comes in…
The Scientific Committee on Consumer Safety is the European Union’s independent scientific panel for evaluating ingredients in personal care products. They require manufacturers to submit their data. They run their own reviews. They look at cell-level effects, inflammation, absorption, what happens when a particle crosses into the bloodstream, what happens when something accumulates in organs. Then they publish a formal opinion, and the EU uses that opinion to decide what’s legal to sell. If only the FDA were so thorough, but I digress!
In June of 2025, the SCCS published their most recent opinion on nano-hydroxyapatite. And they were specific. Rod-shaped particles. Uncoated. Unmodified. Certain aspect ratios. Not needle-shaped, which they explicitly flagged as potentially harmful. Particles meeting those exact specs, and only those specs, they considered safe.
Here’s the line from their opinion: “Any uptake of hydroxyapatite (nano) by buccal mucosa is considered negligible, and the epithelial cells with internalised particles will be shed out over time.”
In plain English: these specific particles don’t accumulate in your body. Cells that happen to pick one up get shed naturally, the way cells in your mouth already do.
That is a huge deal. And it only applies to the specific form of nano-HAP the SCCS evaluated.
The nano-HAP we use in Fygg is called nanoXIM, made by a Portuguese company called Fluidinova. The particles are about 30 nanometers long and 15 nanometers wide. Rod-shaped. Uncoated. Exactly what the SCCS approved for whole-body safety.
The research we invested in…
Full disclosure: I’m a co-founder of Fygg. You know that. One of the things I insisted on from the beginning was that we actually invest in independent research…not to prove we’re right, but to find out if we are. Any brand that asks for your trust should be willing to put their formula under a microscope in public.
So Fygg invested in a peer-reviewed study at Dr. Bennett Amaechi’s lab at UT Health San Antonio—one of the top remineralization researchers in the world. We asked a specific question: how does our formula compare against every other major nano-HAP toothpaste, and against fluoride toothpastes, in head-to-head remineralization?
Every product in the study produced significant remineralization—consistent with the broader literature showing that both nHAP and fluoride can rebuild enamel.
And against prescription-strength fluoride (ClinPro 5000) and standard fluoride (Crest), Fygg performed comparably.
A well-formulated nHAP toothpaste can match what fluoride does.
Here’s what’s telling about the spread. Fygg and Boka both use nanoXIM—the same SCCS-grade nano-hydroxyapatite. And yet Fygg significantly outperformed Boka. Two formulas using the same active ingredient shouldn’t produce nearly-double results. Something else in the formulas separated them.
The formulas stuffed with essential oils, surfactants, and botanicals performed worse. The formula that left all of that out—the one designed to nourish the oral microbiome—performed nearly twice as well. An in vitro study can’t tell us exactly why. But whether those ingredients are interfering with the chemistry in the dish, or damaging the microbiome in a real mouth, or both, the result is the same. They get in the way.
What I told her to look for…
She was right to be in that aisle. But before she grabbed a tube, I gave her three things to check:
1. Count the essential oils and the botanicals. Tea tree, eucalyptus, thyme, wintergreen, peppermint, spearmint, anise—broad-spectrum antimicrobials. They kill the good bacteria along with the bad. Fruit and flower extracts—chamomile, aloe, mango—are cosmetic mimicry and potential oral microbiome disruptors.
2. Look for SCCS-grade nanoXIM—not just any “nHAP.” The grade and particle spec matter more than the percentage. A label that just says “nHAP” tells you nothing about what version is in the tube, or whether anyone has ever evaluated it for whole-body safety.
3. Read past “SLS Free.” Sodium Lauroyl Sarcosinate is a cousin of SLS. Cocamidopropyl Betaine is another. They’re all surfactants, and they all do the same work to the cells in your mouth. “SLS Free” isn’t the same as surfactant-free.
This is why I co-founded Fygg, a formula that treats the oral microbiome as a partner in remineralization, not collateral damage. And then we invested in the research to verify it actually does what we designed it to do.
I hope this was helpful. Hit reply if you have any questions or suggestions for what you’d like me to write about next.
Keep reading those labels,
Mark
P.S. If you’ve already made the switch to nHAP, good for you. You’re ahead of 95% of people. Now flip that tube around and read the rest of the label. That’s where the real difference is hiding.
Further Reading & Citations
Aires, A., Barreto, A.S., & Semedo-Lemsaddek, T. (2021). “Antimicrobial Effects of Essential Oils on Oral Microbiota Biofilms: The Toothbrush In Vitro Model.” Antibiotics, 10(1), 21.
Amaechi, B.T., Tan, A.I., Noureldin, A.A.K., Kanthaiah, K., Holladay, E., Obiefuna, A.C., & Vijayaraghavan, M. (2025). “In vitro evaluation of the ability of nanohydroxyapatite toothpastes to enhance remineralization of enamel caries lesion.” Journal of Dentistry, 161, 106006.