Twice answers a different question from the one our product answers. Twice makes toothpaste, the thing you brush with twice a day. Minvelle is a chewing gum for between brushings, one piece a day, chewed for at least 20 minutes, with 5.7 mg of nano-hydroxyapatite per 1.9 g piece printed on the box. It is an extra step, not a replacement for any toothpaste, Twice's included.

At a glance

Every Twice toothpaste, mapped

Swipe sideways on mobile. Source: smiletwice.com product pages, ingredient panels and catalog feed, checked 26 September 2026. No current Twice tube contains both fluoride and hydroxyapatite. Subscription prices are 15% lower.

Part 1

Which Twice tubes have hydroxyapatite? Two of four

The single most useful thing to know about Twice is that the brand name does not tell you the technology. On 26 September 2026 its store at smiletwice.com listed 11 products: four toothpastes, a mouthwash, three toothbrush packs, floss picks, whitening strips and a gift set. The four toothpastes split cleanly into two pairs. Happy Mint and Charcoal Icy Mint are fluoride-free and built around hydroxyapatite. Wintergreen & Peppermint and Cooling Spearmint are fluoride toothpastes with potassium nitrate and contain no hydroxyapatite at all.

Twice says this itself, in plain terms. Its FAQ, checked the same day, sums up the range as: "Happy Mint: 5% nano-hydroxyapatite for enamel care, with enzymes to help lift surface stains. Fluoride-free. Charcoal Icy Mint: nano-hydroxyapatite, activated charcoal and baking soda for everyday polishing. Fluoride-free. Wintergreen Peppermint: fluoride for cavity protection and potassium nitrate for sensitivity relief. Cooling Spearmint: fluoride cavity protection with a fresh spearmint flavor." That is a clear map, and it is more than many brands give. The practical risk sits with the shopper: if you reorder "Twice" from memory, or pick up a 3-pack from a retail listing, check the flavour name before you check out.

Happy Mint: 5% nano-hydroxyapatite, stated on the tube

Happy Mint is the Twice tube with the clearest hydroxyapatite disclosure. The live product title reads "Happy Mint Whitening Toothpaste with 5% Nano-Hydoxapatite", with the brand's own spelling, followed by "Fluoride-Free & Peroxide-Free, 3.4 oz". The FAQ repeats the figure: "'Nano' describes its small particle size. You'll find it in Happy Mint and Charcoal Icy Mint; Happy Mint contains 5%." And the ingredient panel names the ingredient as "Hydroxyapatite (Nano)". Three places, one consistent number.

The full ingredient list, as published on the Happy Mint product page on 26 September 2026:

Water, Glycerin, Hydrated Silica, Sorbitol, Hydroxyapatite (Nano), Xylitol, Cocamidopropyl Betaine, Sodium Cocoyl Glutamate, Tetrasodium Pyrophosphate, Xanthan Gum, Peppermint (Mentha piperita) Oil, Stevia Leaf Extract, Menthol, Sodium Hexametaphosphate, Spearmint (Mentha spicata) Leaf Oil, Sodium Bicarbonate, Arginine, Bromelain, Papain, Celtic Sea Salt, Green Tea (Camellia sinensis) Leaf Extract, Cardamom (Elettaria cardamomum) Seed Oil, Maltodextrin.

Read in plain English: water, glycerin and sorbitol keep the paste moist; hydrated silica is the polishing agent; nano-hydroxyapatite is fifth on the list, which fits a 5% share; xylitol and stevia sweeten it; cocamidopropyl betaine and sodium cocoyl glutamate are mild foaming agents; tetrasodium pyrophosphate and sodium hexametaphosphate are two phosphate salts. Further down come baking soda, arginine, the two fruit enzymes bromelain and papain, sea salt, green tea extract and cardamom oil. Arginine is an amino acid used in some toothpastes for other purposes; our explainer on arginine toothpaste covers that technology. Twice does not state an amount for it here, and we make no claim about what it does in this formula.

The "whitening" in the name comes from the enzymes, not from peroxide. Twice's product page says papain and bromelain "break down proteins", and the FAQ draws the line clearly: "Happy Mint uses enzymes in a peroxide-free formula. Our Whitening Strips are a separate hydrogen peroxide treatment." If you want to avoid peroxide in a toothpaste, Happy Mint fits; if you want peroxide whitening, Twice sells that as a separate strip product.

Charcoal Icy Mint: nano in the name, not on the panel

Charcoal Icy Mint is also sold as a hydroxyapatite paste. Its live product title reads "NanoHydroxyapatite Fluoride-Free Toothpaste with Charcoal Icy Mint", followed by "Helps Remineralize Enamel", and the product copy says it "combines activated charcoal, baking soda, and nano-hydroxyapatite". Two details differ from Happy Mint, and both matter to a careful buyer.

First, no percentage is stated for this tube anywhere on the site. Happy Mint gets a number; Charcoal Icy Mint does not. Second, the ingredient panel on the same product page lists the ingredient as plain "Hydroxyapatite", without the "(Nano)" qualifier that Happy Mint's panel carries. The marketing text says nano twice, the formal ingredient list does not say it at all. We report that as a documented difference between two parts of the same page, both captured on 26 September 2026, and we draw no conclusion about the particle size inside the tube. The panel reads:

Sorbitol, Hydrated Silica, Water, Glycerin (Vegetable), Xylitol, Cocamidopropyl Betaine, Sodium Bicarbonate, Cellulose Gum, Lauryl Glucoside, Flavor (Natural), Charcoal Powder, Titanium Dioxide, Hydroxyapatite, Sodium Ascorbyl Phosphate (Vitamin C), Retinyl Palmitate (Vitamin A), Tocopherol (Vitamin E), Menthol.

Hydroxyapatite sits 13th of 17 ingredients here, after the flavour, the charcoal and the titanium dioxide. Ingredient lists run in descending order of amount for ingredients above 1%, so a lower position usually means a smaller share, but without a stated percentage we cannot say how much this tube contains. The polishing side of the formula is clearer: Twice's page says "Hydrated silica is a polishing ingredient that helps remove surface deposits as you brush. The formula also includes baking soda and activated charcoal."

What Twice does not disclose for either tube

Two numbers are missing for both hydroxyapatite tubes. The first is particle size. We searched every Twice page we fetched, including the home page, About page, FAQ, all four product pages and Twice's own hydroxyapatite guide, for nanometre figures, microns and "particle size". The only description is the FAQ line "'Nano' describes its small particle size". No size in nanometres, no supplier and no specification is given. The second is RDA, relative dentin abrasivity, the lab score for how abrasive a paste is. No RDA value appears on any of those pages for any Twice toothpaste.

Neither gap is unusual in this category; most hydroxyapatite brands we have reviewed publish less than a percentage. It is still worth knowing if you compare tubes on paper. If a disclosed percentage is your main filter, our ranking of hydroxyapatite toothpastes sorts brands by exactly what they publish.

Part 2

The fluoride tubes: sodium fluoride and potassium nitrate

The other half of the Twice range is a conventional US anticavity and antisensitivity toothpaste. Both Wintergreen & Peppermint and Cooling Spearmint carry the same two active ingredients, as printed on their product pages on 26 September 2026: "Potassium Nitrate 5%", labelled antisensitivity, and "Sodium Fluoride 0.240% (0.15% w/v Fluoride ion)", labelled anticavity. Both are standard actives under the US over-the-counter rules for toothpaste, which is why these two tubes carry a Drug Facts style active-ingredient statement and the hydroxyapatite tubes do not.

Sodium fluoride is the most common fluoride in toothpaste; our comparison of nano-hydroxyapatite and fluoride goes through how the two mechanisms differ. Potassium nitrate is a common ingredient in toothpastes labelled for sensitive teeth, and Twice's labels name it for that purpose. The sensitivity claim is Twice's, on its drug label; we did not test it.

The inactive ingredients

The Wintergreen & Peppermint inactive ingredients on the live page read: "Water • Hydrated Silica • Sorbitol • Glycerin (Vegetable) • Pentasodium Triphosphate • Cocamidopropyl Betaine • Flavor • Retinyl Palmitate (Vitamin A) • Tocopherol (Vitamin E) • Aloe Barbadensis Leaf Juice (Aloe Vera) • Xylitol • Sodium Saccharin • Sucralose • Lauryl Glucoside • Cellulose Gum • Titanium Dioxide • Sodium Benzoate • Citric Acid." Cooling Spearmint uses the same set in a different order. There is no hydroxyapatite in either list.

The FDA labels match the website

Because these two tubes are drug products under US rules, they have structured labels in DailyMed, the US National Library of Medicine's database of drug labels. The newest label for Wintergreen Peppermint (DailyMed set ID 7b7beec2-e070-4102-a2a4-68c332fc9fb3, labeler Twice Twice LLC, updated 19 January 2026, NDC 72164-005) lists exactly the same inactive ingredients as the live product page. That is a good sign: the website and the regulatory label say the same thing.

There is also an older label for the same flavour name, and it differs in one ingredient. The December 2023 label for "Twice Science and Wellness Invigorating Wintergreen and Peppermint" (set ID 7f1f1193-ac0e-4eb9-9357-6bd9ce353007, labeler Smiletwice, Inc., NDC 72164-003-01) includes Sodium Ascorbyl Phosphate (Vitamin C); the January 2026 label and the live page do not. The simplest reading is a reformulation between 2023 and 2026. If you are holding an older tube, its label may differ from the current one.

DailyMed's own interface marks that older 2023 product code with the note "Contains inactivated NDC Code(s)... listed by the FDA initiated compliance action". This is DailyMed's standard tag for a product code that has been marked inactive in the FDA's NDC directory. On its own it is not a recall: the openFDA enforcement database returned no recall or enforcement record for the recalling firm names "Twice" or "GuruNanda" when we searched on 26 September 2026.

Why there is no FDA label for the hydroxyapatite tubes

A DailyMed search for hydroxyapatite under Twice and for Happy Mint returned nothing. That is expected. Happy Mint and Charcoal Icy Mint make no anticavity drug claim with a monograph active, so they are sold as cosmetic toothpastes and do not need a drug label. The absence of a label is not a gap in compliance; it reflects which rules apply to which tube.

Discontinued flavours you may still see

DailyMed also holds labels from December 2023 for two flavours that are no longer in the live catalog: "Calming Vanilla Lavender Mint" (NDC 72164-002) and "Cooling Spearmint Eucalyptus" (NDC 72164-004). Both were fluoride and potassium nitrate formulas. Today's Cooling Spearmint has no eucalyptus in its name. If you find one of these older flavours on a resale listing, treat it as a fluoride paste, not a hydroxyapatite one.

Part 3

What evidence does Twice cite? One trial, described honestly

Twice cites exactly one peer-reviewed study anywhere on its site. It appears on Twice's guide page "Hydroxyapatite vs. fluoride toothpaste", cited as "Paszynska et al., 2023", with a link to the paper's full text. We resolved it in PubMed on 26 September 2026: Paszynska and colleagues, Caries-preventing effect of a hydroxyapatite-toothpaste in adults: a 18-month double-blinded randomized clinical trial, Frontiers in Public Health, 2023 (PMID 37533523, DOI 10.3389/fpubh.2023.1199728, trial registration NCT04756557).

What the trial did

It was an 18-month, double-blinded randomized trial in adults. One group brushed with a fluoride-free hydroxyapatite toothpaste, the other with a toothpaste containing 1,450 ppm fluoride as sodium fluoride. It was designed as a non-inferiority trial, which asks whether the new option is not meaningfully worse than the standard. 189 adults were in the intention-to-treat analysis and 171 completed the study per protocol.

The result, from the PubMed abstract: "According to the PP analysis, no increase in DMFS index was observed in 89.3% of subjects of the hydroxyapatite group and 87.4% of the subjects of the fluoride group. The hydroxyapatite toothpaste was not statistically inferior to a fluoride toothpaste with regard to the primary endpoint." DMFS is a standard count of decayed, missing and filled tooth surfaces. In plain words: over 18 months, the hydroxyapatite group did about as well as the fluoride group on new decay.

Paszynska et al., Frontiers in Public Health 2023, PMID 37533523. Non-inferiority design; this trial did not test any Twice product.

Who funded it

The paper's conflict-of-interest statement reads: "JE, FM, and ESc are employees of Dr. Kurt Wolff GmbH and Co. KG, Bielefeld, Germany. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest." Dr. Kurt Wolff is a German toothpaste manufacturer. Industry involvement does not make a trial wrong, but readers should know about it, and the paper discloses it.

What Twice says about its own evidence

Here Twice does something we have not seen from another brand in this series. Its guide page states the funding in its own words, "Funded by Dr. Kurt Wolff and two universities; three authors were employees of the company", which matches the published statement closely. And it spells out the limit of the evidence for its own product: "What this means for TWICE: the trial did not test our current Happy Mint toothpaste, which contains 5% nano-hydroxyapatite. An ingredient study is not a clinical trial of our finished product."

The same page adds a general warning that applies to every hydroxyapatite brand: "'Nano' describes particle size. Hydroxyapatite formulas can differ in particle characteristics and concentration, so a study of one formula should not be treated as proof for another. Check the product's full ingredient list and the research behind its specific claims." We agree with that sentence, and we apply it to our own gum as well: there is no clinical trial on the finished Minvelle gum either.

The difference that matters for a Twice buyer

The trial tested a 10% hydroxyapatite paste. Happy Mint states 5%. Charcoal Icy Mint states no percentage. So the trial supports hydroxyapatite toothpaste as a category, at the concentration tested, and it does not tell you how either Twice tube performs. Twice says exactly this. If you want more of the published research on hydroxyapatite toothpaste in one place, our article on whether nano-hydroxyapatite is safe covers the safety side, and our comparison of the two actives covers effectiveness.

Twice cites no study at all for its fluoride tubes. It does not need to in the same way: sodium fluoride at that label strength is a long-established anticavity active under US rules. Twice's guide page makes the general point itself: "Decades of cavity-prevention research. The ADA requires fluoride in toothpastes carrying its anticavity Seal." No Twice product page claims the ADA Seal for any Twice tube, and we found no such claim anywhere on the site.

Part 4

Who makes Twice? The company records

Twice is a small, founder-led US brand with named people behind it. Here is what the records show, each checked on 26 September 2026.

The legal entity: Twice Twice LLC

The company name looks like a typo, but it is consistent. Twice's Terms & Conditions define "Twice" as "Twice Twice LLC, a Delaware limited liability company, and its subsidiaries and affiliates". The sweepstakes clause on the same page names the sponsor as "Twice Twice LLC, located at 14 Harrows Lane, Purchase, New York 10577". The site footer reads "© 2026, Twice Twice LLC". The store's checkout names the merchant as Twice Twice LLC, and the FDA label for Twice's Gum Shield mouthwash (DailyMed, updated 2 April 2026) lists Twice Twice LLC as packager. Five sources, one name.

The brand's own domain, smiletwice.com, was registered on 29 May 2016 according to the domain registry record (RDAP), with the last change on 7 May 2025. It is a live store with working checkout. A second domain, twicetwicellc.com, registered in 2024, serves the same store and points search engines back to smiletwice.com as the main address. Several other domains that look related are not the toothpaste brand: twice.com is a consumer-electronics trade publication, and twicetoothpaste.com and hellotwice.com were parked pages when we checked.

An earlier company name on the FDA labels

The 2023 drug labels for Twice toothpastes list the labeler as Smiletwice, Inc.; the 2026 labels list Twice Twice LLC. Both use the same FDA labeler code, 72164. A shared labeler code is consistent with one business changing its name or legal form, but that is our inference from labeling data. We could not confirm it in a company registry, so we do not state it as fact.

The founders

The Better Business Bureau profile for Twice (business name "Twice", 14 Harrows Lane, Purchase, NY, founded 31 January 2017) lists Julian Levine, Co-Founder/CEO and Cody Levine, Co-Founder/Chief Brand Officer. Twice's About page tells the same story in its own words: "Brothers Julian and Cody Levine grew up in a family devoted to dentistry." The Charcoal Icy Mint page quotes Julian Levine as co-founder, and the FAQ even gives his routine: "Julian's personal pairing is Happy Mint in the morning and Charcoal Icy Mint at night."

Their father, Dr. Jonathan B. Levine, DMD, is named on the About page as "TWICE's Chief Dental Advisor". The page describes him as a former associate professor and director of the Advanced Aesthetics Program at NYU, founder of GLO Science and the GLO Good Foundation, and states "35+" years caring for patients and "29" patents in oral care. Those figures are Twice's own; we did not re-count them in a patent database. He is presented as an advisor, not as an officer, and the BBB record does not list him. GLO Science is his own separate company.

The shared customer-service details with GuruNanda LLC

One more set of records is worth reporting, because readers who look closely at the Twice site will find it. Twice's footer gives a customer-service and returns address of 6645 Caballero Blvd., Buena Park, CA 90620, the phone number 866-421-0309, and the email contact@twicetwicellc.com. The footer of gurunanda.com, the site of a separate company, GuruNanda LLC, gives the same address and the same phone number, checked on 26 September 2026.

Twice's refund policy (smiletwice.com/policies/refund-policy, checked the same day) also contains this sentence: "Refunds will be issued for purchases made online through GuruNanda.com."

The BBB lists the two as separate businesses with separate records. Twice: founded 31 January 2017, BBB rating A+, not BBB accredited, 0 complaints closed in the last 3 years, 0 customer reviews, principals Julian and Cody Levine. GuruNanda LLC has its own, separate BBB record, and none of the principals listed there appear on Twice's site.

We could not confirm the relationship between the two companies. The documents show a shared address, a shared phone number and one sentence in Twice's refund policy that names GuruNanda.com. They do not show shared ownership, and the BBB treats the two as separate businesses. We report the records as they stand and add nothing to them.

Part 5

Is there a Twice toothpaste lawsuit? What the dockets show

"Twice toothpaste lawsuit" is a real search, so here is the direct answer: we found no court docket naming Twice, its company or its founders.

On 26 September 2026 we searched CourtListener, the public archive of US federal court records, with six queries. The results:

CourtListener search API, 26 September 2026.

CourtListener covers US federal courts. It does not hold every state-court filing, and a search can miss a case filed under a name we did not try. So this is a good-faith search of the public federal record, not a guarantee that no dispute exists anywhere. We also did not search advertising-review decisions (NAD) this round. If a case is filed, the docket is where to read it, and we will update this page.

Recalls and FDA records

The openFDA enforcement database returned no recall or enforcement action for "Twice" as the recalling firm on 26 September 2026. DailyMed lists 8 label records for Twice products, all over-the-counter labels, under the two company names described in Part 4. The one older product code marked inactive is covered in Part 2; DailyMed's tag describes the code's status in the FDA directory and is not a recall.

Part 6

Price, subscription and returns: the fine print

Twice keeps its pricing simple. On 26 September 2026 every toothpaste on smiletwice.com cost $8.99 for a 3.4 oz tube. Happy Mint, Charcoal Icy Mint and Wintergreen & Peppermint also came in a 3-pack for $19.99, about $6.66 a tube; Cooling Spearmint had no 3-pack listed. The Complete Oral Care Gift Set, $34.99, contains Happy Mint and Charcoal Icy Mint, the Gum Shield mouthwash, 75 floss picks and 2 toothbrushes, so it holds both hydroxyapatite tubes and neither fluoride tube.

Subscription

Twice's FAQ says: "Subscribe to eligible products and save 15% on every delivery. Choose an available delivery interval on the product page." We checked the numbers on the Happy Mint page: $8.99 one-time against $7.64 on subscription, and $19.99 against $16.99 for the 3-pack, both exactly 15% off. The page offers two delivery options; we could not read which intervals they are from the page data, so check the selector before you subscribe.

Shipping

The site banner reads "Free shipping on orders over $50", and the FAQ narrows it: "Retail orders over $50 qualify for free shipping within the continental United States. Dental professional orders are excluded. We currently cannot fulfill international orders." If you are outside the US, smiletwice.com will not ship to you. Twice's FAQ also names Walmart and Amazon as places to buy, with "products and availability vary"; we do not link marketplace listings.

Returns

Twice's refund policy is short and strict: "Unopened and unused returns are accepted within 7 days from the date of delivery... we do not offer free returns unless package protection was purchased at checkout... we do not offer exchanges, only replacements for the same item." Clearance items are excluded. The product page summary says the same thing in one line: "Returns: unopened, unused items within 7 days of delivery. Fees and exclusions apply."

Two points in Twice's favour here. First, the product page and the policy agree; there is no "money-back guarantee" or "risk-free" line on the site sitting on top of stricter terms. We searched the home page, About page, FAQ and all four toothpaste pages for that kind of wording and found none. Second, the policy is stated once and plainly. The practical point for a buyer: 7 days is short, and an opened tube cannot be returned, so a first order of a single $8.99 tube is a cheaper test than a 3-pack. The GuruNanda sentence in the same policy is covered in Part 4.

Reviews

Twice's Trustpilot profile had no reviews at all on 26 September 2026, and it is unclaimed. The BBB has no complaints and no customer reviews on file for Twice. That is a clean record, but a thin one: it tells you nothing has been reported, not that many people have tested the brand.

The star ratings on Twice's own product pages come from a review widget that Twice runs itself, so they are not independent. The counts vary a lot by tube:

Brand-hosted review widget, read from each product page's structured data on 26 September 2026. Not an independent source.

The fluoride Wintergreen & Peppermint, the brand's oldest tube on its FDA record, has by far the most reviews. Happy Mint, the tube with the clearest hydroxyapatite disclosure, has two. A 5.0 from two reviews says very little either way. We did not base this review on Reddit threads or other forum posts; if you read them, weigh single experiences as single experiences.

Part 7

Twice vs Boka, and how to compare any two tubes

"Twice toothpaste vs Boka" is another common search. Twice has never published that comparison. Its own "Why you should choose Twice" page names two competitors, Colgate Sensitive Pro Relief and Quip Anticavity Toothpaste, in two blog posts that cite no studies, and the word Boka appears nowhere on the Twice pages we read. So any Twice vs Boka comparison has to be built from each brand's own label.

Our Boka toothpaste review documents what Boka publishes, checked with the same method as this page. To set the two side by side, look at the same four things for each brand:

• Is the hydroxyapatite percentage stated? For Twice: yes for Happy Mint (5%), no for Charcoal Icy Mint.
• Does the ingredient panel say "nano"? For Twice: Happy Mint's panel does, Charcoal Icy Mint's does not.
• Is fluoride in the tube? For Twice it depends on the flavour; for a hydroxyapatite-only brand, check the panel.
• What does a tube cost per ounce, and does it ship to you? Twice: $8.99 for 3.4 oz, US only.

If you are choosing among fluoride-free tubes in general, our ranking of fluoride-free toothpastes covers the wider field, and our sibling guide to the best remineralizing toothpastes by active sorts the options by need rather than by brand.

How to pick the right Twice tube, in five steps

• Decide on fluoride first. If your dentist wants you on fluoride, pick Wintergreen & Peppermint or Cooling Spearmint. If you have decided with your dentist to brush without fluoride, pick Happy Mint or Charcoal Icy Mint.
• If you want hydroxyapatite with a stated amount, Happy Mint is the only Twice tube that gives one: 5%.
• If you want polishing agents, Charcoal Icy Mint adds charcoal and baking soda; Happy Mint uses enzymes and is peroxide-free.
• If you are buying for sensitive teeth, the fluoride tubes carry potassium nitrate 5%, labelled by Twice as antisensitivity. The hydroxyapatite tubes make no such label claim. Ask your dentist which fits.
• Check the flavour name on every reorder and every retail listing, because "Twice toothpaste" alone can mean either technology.

Part 8

Twice and a nano-hydroxyapatite gum: different tools

You may be here because you are weighing hydroxyapatite against fluoride. We sell a nano-hydroxyapatite product, so here is our position plainly. Fluoride is not the enemy. A fluoride toothpaste brushed twice a day is what most dentists recommend as the base of home care, and Twice's fluoride tubes are a standard example. Hydroxyapatite toothpaste is a real alternative for people who choose it, and the trial Twice cites found a 10% hydroxyapatite paste not inferior to a fluoride paste over 18 months. Either kind of tube can be the base.

A nano-hydroxyapatite gum does a different job at a different time. You brush in the morning and at night. Between those two moments you eat and drink, and the mouth goes through acid swings. A sugar-free gum chewed after a meal increases saliva flow, and ours adds a measured amount of nano-hydroxyapatite during that time. That is an extra step, not a substitute for either Twice formula.

What a gum cannot do

• It does not replace brushing. A gum does not remove plaque the way a toothbrush and paste do.
• It does not replace fluoride toothpaste. If your dentist has recommended fluoride, keep using it.
• It does not repair a cavity. No gum and no toothpaste fills a hole in a tooth. That is a job for a dentist.
• It does not bleach teeth. There is no peroxide in it; at most it helps with surface stains between brushings.
• It has not been in a clinical trial. There is no clinical trial on the finished Minvelle gum. What we publish is the dose, the full ingredient list and a batch certificate from lab testing of the finished gum.

Minvelle prints the dose on the box: 5.7 mg nano-hydroxyapatite per piece. See the gum.

In fairness

What Twice does well

A review built on documents owes the brand the documents in its favour, and Twice has several. The strongest is its honesty about evidence. Twice cites one trial, names its funder and the employed authors in its own words, and states that the trial "did not test our current Happy Mint toothpaste". It also warns readers that a study of one hydroxyapatite formula is not proof for another. No other brand we have reviewed in this series has written that about its own product.

It publishes full ingredient panels for every toothpaste on the product page, not in a PDF or behind a login, and the panels for its fluoride tube match the FDA's structured label word for word. It states a percentage for Happy Mint in three places. It explains the difference between its two technologies on its FAQ instead of blurring them. It has named founders confirmed by an independent BBB record, a domain registered since 2016, no FDA enforcement record, no federal docket naming it, a BBB A+ rating and zero complaints. Its return terms are strict, but the product page states them exactly as the policy does, with no guarantee language on top.

And it is inexpensive: $8.99 a tube, less on a 3-pack or subscription. For a US buyer who wants to try hydroxyapatite toothpaste, that is a low-cost way to start.

The points a reader should still know, the missing percentage and missing "(Nano)" on the Charcoal Icy Mint panel, no particle size or RDA for either hydroxyapatite tube, the 7-day return window, US-only shipping, and the shared customer-service details with GuruNanda LLC, do not cancel any of that. They are the record, reported alongside it.

The verdict

Twice toothpaste, in one paragraph

Twice is a small US toothpaste brand sold at smiletwice.com by Twice Twice LLC, founded by Julian and Cody Levine, with their father Dr. Jonathan B. Levine as dental advisor. It sells two technologies under one name. Happy Mint states 5% nano-hydroxyapatite and is fluoride- and peroxide-free; Charcoal Icy Mint is sold as nano-hydroxyapatite and fluoride-free, with no stated percentage and a panel that says only "Hydroxyapatite". Wintergreen & Peppermint and Cooling Spearmint are sodium fluoride and potassium nitrate pastes with no hydroxyapatite. Every tube is 3.4 oz and $8.99. Twice cites one trial and says plainly that it did not test Twice's product. We found no federal lawsuit, no FDA enforcement record and no Trustpilot or BBB complaints, and we could not confirm the relationship between Twice and GuruNanda LLC beyond a shared address, phone number and refund-policy sentence.

Who it suits: US buyers who want an inexpensive hydroxyapatite toothpaste with a stated percentage (Happy Mint), or an inexpensive fluoride paste with potassium nitrate. Who should look elsewhere: readers outside the US, since Twice does not ship internationally, and readers who want a disclosed particle size or a stated percentage on every hydroxyapatite tube.

Where Minvelle fits, briefly. A gum does not replace a toothpaste. Minvelle is an add-on for between brushings: one piece a day, chewed for at least 20 minutes, with 5.7 mg of nano-hydroxyapatite per piece printed on the box and a published batch certificate. There is no clinical trial on the gum itself, and we say so for the same reason Twice says it about Happy Mint.

Facts checked on 26 September 2026 from the sources below. If Twice changes its pages, formulas or prices, tell us and we will update this review.

Questions, answered

The things people actually ask