Underbrush gum review: what's verified, what's marketing (2026)
Two fluoride-free nano-hydroxyapatite gums. I founded Minvelle, so you know my bias upfront. Underbrush is a genuinely good product, and there are people I would send to it instead of us. Here is the comparison I would want if I were spending my own money.
Both gums are fluoride-free and built on nano-hydroxyapatite plus xylitol, and neither has a finished-product clinical trial, so the honest tiebreakers are the chew and the whitening angle. Underbrush is a firm tree-sap and resin chew, its official pages make no whitening claim, and its subscribe price is very fair. Buy it if you want a substantial, long-holding chew and do not care about brightening. Minvelle
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is a softer chew that additionally helps polish away surface stains, peroxide-free, for a whiter, glossier smile. Buy it if the coffee-teeth, whiter-smile angle is what pulled you here. Right fit for Minvelle: daily coffee and wine drinkers who also want the surface-brightening. Wrong fit: anyone expecting either gum to replace brushing or bleach deep stains.Underbrush is a fluoride-free nano-hydroxyapatite gum, and the verified part is the formula and the restraint: nano-hydroxyapatite, xylitol and a chicle, mastic and spruce gum base, no whitening claim on its official pages, the standard FDA disclaimer. What is not verified is the gum itself. Underbrush has published no clinical trial on its finished product, and neither has Minvelle, so every efficacy statement on either side rests on ingredient-level research done mostly on toothpaste and lab enamel models. That leaves two honest tiebreakers: the chew and the whitening angle. Underbrush is a firm resin chew with no brightening claim. Minvelle is a softer chew that also helps polish away surface stains, peroxide-free.
How to read this table: first column Underbrush by Nathan & Sons (US), second column Minvelle (Austria), third column whether each line is verified or a claim. "Verified" means published by the brand itself or listed on its own pages, not proven in a trial on the finished gum. Two fluoride-free nano-hydroxyapatite chewing gums, compared by the founder of Minvelle. Last reviewed: August 29, 2026. Swipe sideways on mobile.
| What's compared | Underbrush | Minvelle | Verified or claim |
|---|---|---|---|
| Active ingredients | Nano-hydroxyapatite plus xylitol, fluoride-free | Nano-hydroxyapatite plus xylitol, fluoride-free | Verified from both brands' published ingredient lists |
| The chew | Firm chicle, mastic and spruce gum base | Softer chew, Chios mastic and botanical resins | Verified, and it is a preference, not a performance gap |
| Whitening angle | No whitening claim on its official pages | Helps polish away surface stains, peroxide-free | Brand claim, surface and optical effect only, not bleaching |
| Evidence on the finished gum | No published trial on the gum | No published trial on the gum | Verified gap on both sides, all claims sit at ingredient level |
| Price | USD 29.99 one-time, USD 20.99 subscribe (nathanandsons.com) | EUR 24.99 per box of 18 pieces, one piece a day | Verified from public listings, check the current one before ordering |
| Best for | A firm, long-holding chew when brightening does not matter | Coffee and wine drinkers who want the surface brightening too | A fit judgment, not a ranking of which gum works better |
If the coffee-teeth, surface-brightening angle is why you're here, Minvelle is the pick of the two. Full comparison continues below.
Try Minvelle with code ENAMEL15 →Fluoride-free oral care stopped being niche this year. Two US states now require non-fluoridated municipal water by law, so a lot more people are typing "fluoride-free" into a search bar and finding nano-hydroxyapatite for the first time. The EU's Scientific Committee on Consumer Safety has assessed nano-hydroxyapatite as safe for oral care at the ingredient level, and hydroxyapatite toothpaste has gone mainstream in European drugstores. Underbrush and Minvelle are two of the most searched dedicated nano-hydroxyapatite gums, which is exactly why people cross-shop them in one session. If you found this page by searching Underbrush, you are in the right place.
- Glossary: five terms this comparison leans on
- Is Minvelle or Underbrush the better gum?
- How do they compare head to head?
- What do the ingredient lists actually say?
- Where does Underbrush win?
- Where does Minvelle win?
- How honest are the claims on both sides?
- How to use whichever gum you pick
- What results should you expect, and when?
- Which gum is right for you?
- What the research says about the shared active
- How I built this comparison
Glossary: five terms this comparison leans on
A synthetic form of calcium phosphate, closely analogous to the mineral your enamel is made of (enamel is roughly 97 percent mineral, mainly hydroxyapatite), at particle sizes small enough to interact with the enamel surface. The active in both gums compared here.
The redepositing of calcium and phosphate into enamel that acid has weakened. Saliva drives it naturally. A remineralization-support product aims to supply extra mineral during the recovery window after eating and drinking.
A sugar alcohol that the bacteria most linked to cavities cannot use for fuel. It is a common sweetener in sugar-free oral-care gum and is present in both Minvelle and Underbrush.
Surface (extrinsic) stains sit on the outside of the tooth: coffee, tea, red wine, tobacco. Intrinsic stains live inside the tooth structure and only bleaching or dental work touches them. When Minvelle talks about a whiter smile, it means the surface layer only.
Research on an ingredient (usually in toothpaste or lab enamel models) rather than on the finished product. Every efficacy statement both brands make sits at this level. Neither has published a trial on its actual gum.
Is Minvelle or Underbrush the better gum?
On the core mechanism they are close: both are fluoride-free gums built on nano-hydroxyapatite plus xylitol, and neither brand has published a clinical trial on its finished gum. So do not choose on "which one remineralizes more," because nobody can answer that with current evidence. Choose on the two things that actually differ: the chew, and whether you want surface brightening. Underbrush is a firm tree-sap and resin chew with no whitening claim on its pages. Minvelle is a softer chew that also helps polish away surface stains, peroxide-free, for a whiter, glossier smile. The rest of this page walks through that in detail, including where Underbrush is the better call.
How do Minvelle and Underbrush compare head to head?
Minvelle vs Underbrush head to head: first column Underbrush by Nathan & Sons (US), second column Minvelle (Austria). Both are fluoride-free nano-hydroxyapatite chewing gums; "verified" keeps the same meaning as above: published by the brand itself, not proven in a trial on the finished gum. Compiled by the founder of Minvelle, last reviewed August 22, 2026.
| Feature | Underbrush | Minvelle |
|---|---|---|
| Category | Fluoride-free nHAp gum | Fluoride-free nHAp gum |
| Primary active | Nano-hydroxyapatite | Nano-hydroxyapatite |
| Whitening / brightening | No whitening claim on official pages | Helps polish away surface stains, peroxide-free, for a whiter, glossier smile |
| Chew | Firm tree-sap and resin chew | Softer chew |
| Other ingredients | Xylitol, chicle, mastic, spruce gum | Xylitol, Chios mastic and botanical resins |
| Fluoride | Free | Free |
| Suggested use | Daily chew, see brand for count | One piece a day, 18-piece box (18-day supply) |
| Price | USD 29.99 one-time, USD 20.99 subscribe (nathanandsons.com) | EUR 24.99 per box |
| Brand | Underbrush by Nathan & Sons (US) | Minvelle (Austrian brand) |
| Claims posture | Restrained, carries the standard FDA disclaimer | Cosmetic and structure-function only, no cure language |
| Best for | People who want a firm, long-holding chew and do not care about whitening | Coffee and wine drinkers who also want surface brightening and a softer chew |
Read the table once and the pattern is clear: the two products agree on the science and diverge on feel and finish. That is normal for this category. It means the decision is less "which one remineralizes better" (unanswerable today) and more "do I want a firm chew, or a softer chew that also works on coffee stains." The next sections take those trade-offs one at a time.
What do the ingredient lists actually say?
Here is the thing most competitor comparisons get wrong: these two formulas are more alike than different. Both lead with nano-hydroxyapatite. Both use xylitol. Both build the chew on tree resins rather than a synthetic polymer base. If you were expecting me to tell you Underbrush is the cheap knockoff, I am not going to, because it is not.
Underbrush. Its ingredient page lists nano-hydroxyapatite, xylitol, chicle, mastic and spruce gum. That resin base is what gives it the firm, substantial chew, closer to chewing actual tree sap than to a supermarket stick. It is a clean, coherent formula, and I respect it.
Minvelle. Same nano-hydroxyapatite active, same xylitol, and we also use Chios mastic and a botanical resin blend. The difference you will feel is that our chew is softer, which for most people makes it easier to start on and easier to turn into a daily habit. The difference you will see is the finish: Minvelle is formulated to help polish away surface stains, peroxide-free, so it does double duty on the coffee-teeth problem. Underbrush does not claim that.
Which is right? The evidence does not crown one on remineralization, because the active is the same and neither gum has its own trial. What you are really choosing is texture and finish: a firm resin chew that stays out of the whitening lane, or a softer chew that also helps brighten the surface. Both are defensible. If you want the deeper background on how the shared active works, our remineralizing gum guide covers the ingredient science in detail.
Where does Underbrush win?
Credit where it is due, and in a few cases the credit points away from my own product. The title of this page promises honesty, so here it is.
Underbrush's chicle, mastic and spruce base gives a firm, substantial chew that a lot of people genuinely prefer. If you like a gum you can work on, that feels dense and holds up, this is a real strength and our softer chew is not for you.
Underbrush's official pages do not overreach. They make no whitening claim and they carry the standard FDA disclaimer. In a category full of "rebuild your enamel" nonsense, a brand that stays inside its evidence is worth trusting, and they do.
At USD 20.99 on subscribe-and-save, Underbrush is priced well. This is not a comparison you should decide on money, and I am not going to pretend we undercut them. Their subscribe price is good, full stop.
Underbrush is a US brand (Nathan & Sons). If buying from a domestic brand matters to you, that is a legitimate reason to go with them, and no formula argument changes it.
Where does Minvelle win?
A few cases point the other way, and they are the reason the product exists.
Helps polish away surface stains for a whiter, glossier smile. This is the clearest gap. Underbrush's pages make no whitening claim, so it is a remineralization-support gum only. Minvelle is built to do both: support enamel remineralization and help lift the surface stains coffee and wine leave behind, with no peroxide and none of the sensitivity that peroxide can cause. To be precise, this is a surface and optical effect, not bleaching.
One piece a day, chewed after your coffee. That is the whole routine. The softer chew makes it easy to reach for, and the moment right after coffee is exactly when surface stain and acid are both in play. A single 18-piece box is an 18-day run at that pace.
Approachable texture. A firm resin chew is great if you want it, but it is a commitment. Minvelle's softer chew is the one most people settle into as a daily habit, and a habit you keep beats a texture you admire and abandon.
Nano-hydroxyapatite can help relieve tooth sensitivity. This is true of the ingredient in both gums, so it is not a knockout over Underbrush. But if mild sensitivity is part of why you are shopping, it is worth knowing the active is the same one studied for that.
How honest are the claims on both sides?
This is the section most comparisons skip, because it means saying something uncomfortable: neither brand has published a clinical trial on its finished gum. Not Underbrush, not Minvelle. Every efficacy statement either company makes rests on ingredient-level research, most of it done on toothpaste and lab enamel models, not on gum.
Why does the whole category run on ingredient evidence? Because finished-product trials are slow and expensive, and the gum niche is young. A properly powered trial runs well over a year with hundreds of people, a budget neither a bootstrapped Austrian brand nor a US startup has sitting around. That is an explanation, not an excuse. It means you should read every claim in this category with the ingredient-versus-product distinction in mind.
To both brands' credit, the marketing mostly respects that line. Underbrush positions its gum as a complement to brushing and avoids cure language, and it carries the standard disclaimer. Minvelle does the same. We say "supports enamel remineralization" and "helps polish away surface stains" because that is what the ingredient evidence licenses, and nothing more. We do not say the gum rebuilds enamel, reverses cavities, or is clinically proven, because none of that is true for any gum on the market. On whitening specifically, we mean the surface layer only. It is not bleaching and it will not lift deep stains. Where you should raise an eyebrow, with us or anyone, is any phrasing that drifts from "the ingredient has been studied" toward "this gum is proven." Our full breakdown of that evidence gap lives in does remineralizing gum actually work.
How to use whichever gum you pick
The playbook is the same for both, because it follows from the chemistry, not the brand. Enamel starts to demineralize when the pH at the tooth surface drops below about 5.5, and everyday drinks sit well under that line: coffee around pH 4.8, wine around 3.5, citrus juice around 2.5. Each of those opens a recovery window where saliva buffers the acid and carries mineral back to the surface. A nano-hydroxyapatite gum is built to work inside that window.
- Chew soon after coffee or a meal. Right after the morning coffee is the highest-value moment of the day, and after dinner is next. Whichever brand is in your pocket, the timing is the same.
- Chew for 10 to 20 minutes. Saliva stimulation and contact with the active both need time. A gum you actually keep chewing does more than one you spit out early.
- Make it daily, not occasional. With Minvelle that is one piece a day. Consistency is what lets mineral support keep pace with daily acid exposure.
- Change nothing else. Keep brushing twice a day and flossing. Both brands say this, and they are right. The gum covers the hours between brushings, nothing more.
What results should you expect, and when?
The same expectations apply to both gums, because the active is the same. Anyone selling you a two-week enamel transformation is selling you a story. Here is the honest timeline.
First weeks: surface finish and sensitivity. The surface-brightening effect, the coffee-stain side, is the one you may notice earliest, because it is a surface effect. Milder sensitivity is the other early change people report from nano-hydroxyapatite, since the ingredient has been studied for helping relieve it. Both are gradual, not overnight.
Months, not weeks: enamel support. Remineralization support plays out at a microscopic scale over months of consistent use. The realistic checkpoint is your next dental visit. Neither gum changes that timeline, and neither brand honestly can.
Never: fixing an actual cavity. A cavity that has broken through the surface needs a dentist. These gums support early-stage enamel and surface stain, nothing beyond that. If any gum's marketing implies it repairs cavities or rebuilds lost enamel, close the tab. Ours does not say it, and neither does Underbrush.
Which gum is right for you?
Minvelle. This is the core case. It supports remineralization and helps polish away the surface stains coffee and wine leave, peroxide-free, in a softer daily chew. Underbrush does not claim the whitening side.
Underbrush. The tree-sap and resin base is the point. If you like a dense chew that holds up and you are only after remineralization support, they do it well.
Underbrush. At USD 20.99 on subscribe, it is priced well. If money is the only lever that matters to you, that is an honest reason to pick it.
Pick by what you want to feel and see. The active is identical. Want the whiter-smile angle and a softer chew: Minvelle. Want the firm resin chew and nothing else: Underbrush. Both brands will still be here if you switch.
What the research says about the shared active
Since both gums stand on the same ingredient, the state of nano-hydroxyapatite research is the real foundation here. The idea is biomimetic: enamel is roughly 97 percent mineral, mainly hydroxyapatite, and nano-hydroxyapatite supplies that same mineral in particles small enough to interact with the enamel surface. It has history behind it. Hydroxyapatite has been used in oral care in Japan since the 1980s and was approved there as an active anticaries agent in 1993.
On safety, the EU's Scientific Committee on Consumer Safety has assessed nano-hydroxyapatite as safe for oral care at the ingredient level, which matters for something you chew daily. That assessment was of toothpaste and mouthwash, so read it as clearance for the ingredient, not a stamp on any specific gum. On efficacy, an 18-month randomized trial (Paszynska et al., Frontiers in Public Health, 2023, n=189, PMID 37533523) found a hydroxyapatite toothpaste non-inferior to fluoride toothpaste for caries prevention in adults, and later meta-analyses have supported the ingredient for enamel support and for helping relieve sensitivity. All of that is toothpaste and in-situ evidence, not gum.
So a nano-hydroxyapatite gum, from either brand, is a well-reasoned bet on a studied ingredient delivered in a format that stimulates saliva, not a clinically proven device. That is the honest place to leave it: strong ingredient, sensible format, no finished-gum study yet. For the mechanism story against fluoride, see our piece on nano-hydroxyapatite vs fluoride.
How I built this comparison
A comparison written by one of the two competitors deserves a methods note. The Minvelle side draws on our own published ingredient list, price and usage, which you can verify on the product page. The Underbrush side draws on the brand's own public pages: its listed ingredients (nano-hydroxyapatite, xylitol, chicle, mastic, spruce gum), its resin chew, its pricing on nathanandsons.com, and the fact that its pages make no whitening claim and carry the standard FDA disclaimer. Where a detail could change, check the current listing before you order.
And the bias disclosure, in plain words: Minvelle pays my rent. That is exactly why the Underbrush-wins section is real and specific. A comparison that never concedes anything is an ad, and you would be right not to trust it. If you catch an error in either column, our contact page is open and corrections get made.
Frequently asked questions
Is Minvelle or Underbrush the better remineralizing gum?
On the core mechanism they are close: both are fluoride-free gums built on nano-hydroxyapatite plus xylitol, and neither brand has published a clinical trial on its finished gum. The real differences are the chew and the whitening angle. Underbrush is a firm tree-sap and resin chew and its official pages make no whitening claim. Minvelle is a softer chew that additionally helps polish away surface stains, peroxide-free, for a whiter, glossier smile. Pick on which of those you actually want.
Does Underbrush whiten teeth, and does Minvelle?
Underbrush's official pages make no whitening claim, so treat it as a remineralization-support gum. Minvelle is formulated to help polish away surface stains, peroxide-free, for a whiter, glossier smile. That is a surface and optical effect only. It is not bleaching, it will not lift deep or intrinsic stains, and it will not change your tooth shade by a set number of steps.
How do Minvelle and Underbrush compare on price?
Both sit in the same band. Underbrush lists at USD 29.99 one-time, or USD 20.99 on subscribe-and-save on nathanandsons.com. Minvelle is EUR 24.99 for a box of 18 pieces, one piece a day. That subscribe price on the Underbrush side is genuinely good, so this is not a comparison you should decide on price. Decide it on the chew and the whitening angle instead.
Are both gums fluoride-free?
Yes. Both Minvelle and Underbrush are fluoride-free and both use nano-hydroxyapatite, the mineral closely analogous to what your enamel is made of, as the active. If you are shopping specifically to skip fluoride, both belong on your list. Fluoride-free is not a point of difference between these two.
Can I chew either gum instead of brushing my teeth?
No, and neither brand claims you can. Brushing mechanically removes plaque, which no gum does. Both Minvelle and Underbrush are for the hours between brushing, when acid from coffee, wine and meals is working on your enamel and saliva is your main defense. Keep brushing twice a day and flossing, and use the gum after coffee or a meal.
Which one chews better?
That is personal. Underbrush is a firm, substantial chew built on tree sap and resin (chicle, mastic and spruce gum), which some people love for how long it holds up. Minvelle is a softer chew that is easier to start on and, for me, easier to make a daily one-after-coffee habit. Neither texture changes what the nano-hydroxyapatite does. Pick the mouthfeel you will actually reach for every day.
Is Underbrush gum legit?
Yes. Underbrush is a real product from Nathan & Sons in the US, with a published ingredient list, a working store, and, to its credit, restrained marketing: its official pages make no whitening claim and carry the standard FDA disclaimer. Nothing about it reads like a scam. The honest caveat, which applies to Minvelle too, is that no finished-gum clinical trial has been published by either brand, so "legit company" and "clinically proven gum" are two different statements. The first is true of both. The second is true of neither, yet.
Does Underbrush gum actually work?
The evidence sits at ingredient level, not gum level. A 2022 review in Clinical Oral Investigations (Wierichs and colleagues, PMID 35103837) looked at ten human studies of nano-hydroxyapatite, five in vivo and five in situ, mostly in toothpaste, and found remineralizing potential comparable to fluoride under remineralizing conditions, while calling the overall evidence not yet conclusive. Xylitol has its own Cochrane-reviewed record in sugar-free gum. What neither Underbrush nor Minvelle has is a published trial on the finished gum itself, so "does it work" honestly means: the actives have real research behind them, the specific gum has not been tested in a trial.
Is Underbrush gum recommended by dentists?
Underbrush's official pages list no professional-body endorsement, and the same is true of Minvelle. What you will find is individual dentists discussing hydroxyapatite oral care in general, some enthusiastically, some preferring fluoride's longer evidence base. The near-universal dentist position on any oral-care gum is the one worth internalizing: it can supplement brushing during the day, it can never replace it. If a dentist review is what you were searching for, ask your own dentist about hydroxyapatite gum at your next visit; it is a well-known ingredient category by now and you will get an informed answer for your specific teeth.
Can Underbrush gum reverse cavities?
No, and be suspicious of any gum that says otherwise. Once decay has broken through the enamel surface and formed an actual cavity, no gum, paste or rinse rebuilds it; that is dental work. Remineralization applies to the stage before that, when acid has weakened the enamel surface but not yet broken it, which is the window a mineral-support gum is aiming at. Underbrush, to its credit, does not claim to reverse cavities on its official pages. If you suspect you already have one, the useful purchase is a dental appointment, not a subscription to anyone's gum, ours included.
Is Underbrush gum worth it?
If you want a firm, long-holding natural chew and brightening is not on your list, yes, its subscribe price is genuinely fair for the category. The worth-it test for any oral-care gum is boringly practical: will you actually chew it every day? A gum you abandon in a drawer after a week is not worth any price. If you like a firm resin chew, Underbrush clears that bar. If you want a softer chew or the coffee-stain angle matters to you, that is the case where I would point you to Minvelle instead.
Who makes Underbrush gum? Nathan & Sons, explained
Underbrush is made by Nathan & Sons, a US company, and the gum is marketed under both names, which is why searches for "Nathan and Sons gum" and "Underbrush gum" lead to the same product; the official store sits at nathanandsons.com. If you arrived here looking for a Nathan & Sons gum review, this page is about that exact gum: same firm tree-sap chew, same nano-hydroxyapatite and xylitol formula, same pricing discussed in the comparison above. Nothing about the maker's two names changes any conclusion in this review; it is one product with a company name and a product name, a naming pattern plenty of small brands use.
Comparing brands in this category is hard because most publish nothing you can check.
We keep a public database of what every brand actually discloses, ours included, with sources for every cell. Start there, not with anyone's marketing, including ours.
The gum database, every brand compared →Or go straight to our gum and its receipts
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.Minvelle is built around one idea: nano-hydroxyapatite not only twice a day at the sink, but between brushings, where most of the acid and staining happens. Yes, this comparison covers our own product. The trade-offs above are the same ones we talk about internally, including the cases where Underbrush is the better buy.
Every Minvelle post is fact-checked against primary sources and edited line by line before it goes live. No LLM-generated content ships unedited. More on how this brand started →
This article is for information. It is not medical advice. Talk to your dentist before you change your oral-care routine, especially if you have active caries, sensitivity beyond mild, dry mouth, or a condition that affects oral health. Remineralizing gum, from any brand, supports brushing, flossing and professional care. It does not replace them and it does not treat decay. Individual results vary with diet, saliva, baseline enamel and how consistently you use it.
- EU Scientific Committee on Consumer Safety (SCCS) – ingredient-level safety assessment of nano-hydroxyapatite in oral care (toothpaste and mouthwash).
- Paszynska E. et al., 18-month non-inferiority randomized trial of hydroxyapatite vs fluoride toothpaste for caries prevention in adults (PMID 37533523), Frontiers in Public Health, 2023.
- Wierichs R.J. et al., "Efficacy of nano-hydroxyapatite on caries prevention: a systematic review and meta-analysis" (PMID 35103837), Clinical Oral Investigations, 2022 – five in vivo and five in situ studies; same remineralising potential as fluoride under remineralising conditions, evidence graded very low.
- Meta-analyses on nano-hydroxyapatite for enamel support and dentin hypersensitivity, Journal of Dentistry.
- Surface and optical effects of hydroxyapatite on enamel, Dentistry Journal, 2023.
- History of hydroxyapatite in oral care in Japan since the 1980s (approved as an active anticaries agent in 1993), review literature.