At a glance

Four ways to a whiter look, compared

Swipe sideways on mobile. Summary of the studies and documents cited in Parts 1 to 5, checked 26 September 2026.

Part 1

What does whiten mean? Two kinds of tooth color

Before you can judge a whitening claim you need to know which color it is talking about, because teeth have two. The first is surface stain, called extrinsic stain: pigment from drinks, food and smoking that clings to the outer surface of the enamel and to the thin protein film that covers it. The second is the tooth's own color, called intrinsic color. It comes from inside the tooth: from the yellower dentin under the enamel, and from the structure of the enamel itself, which decides how much of that dentin shows through.

These two are removed in different ways. Surface stain can be scrubbed, polished, dissolved or lifted. Inner color cannot be brushed off, because it is not on the surface. To change it, something has to reach into the tooth and change the color molecules there. That is what peroxide does, and it is why the word whitening means two very different things depending on the product.

A long review of whitening toothpastes by Joiner, a scientist at Unilever Oral Care, sets out the framework the whole field uses. Its key sentence: "One of the key functional ingredients in whitening toothpastes is the abrasive system." The review goes on: whitening toothpastes "may contain additional agents that augment the abrasive cleaning by aiding the removal and/or prevention of extrinsic stains, for example, peroxide, enzymes, citrate, pyrophosphate and hexametaphosphate, or optical agents such as blue covarine which can improve tooth whiteness following tooth brushing" (Joiner, 2010, PMID 20562012). In plain terms, most whitening toothpaste works on surface stain, and the abrasive does most of that work.

Where hydroxyapatite could fit

Hydroxyapatite is the calcium phosphate mineral that enamel is mostly made of. In a toothpaste, there are two ways it could make teeth look brighter. The first is mechanical: like any fine mineral powder, it could polish surface stain away. The second is optical: particles could settle on the enamel, fill tiny surface defects and scatter light back toward the viewer, so the tooth looks brighter and glossier without any change inside it.

The optical idea rests on physics papers from the 1990s. One group shone a laser through thin slices of human enamel and concluded: "the prisms are the most important scatterers but that the crystals are responsible for the back-scattering" (Zijp et al., 1995, PMID 8600186). Back-scattering is light bouncing back toward your eye, which is what you see as brightness. A second paper from the same group found that "for enamel the results indicate that the hydroxyapatite crystals contribute significantly to scattering" (Vaarkamp et al., 1995, PMID 7867056). Neither paper tested a toothpaste. They explain why a layer of apatite crystals on the surface could, in principle, change how bright a tooth looks.

The mechanical route has its own classic paper. In a small study, three people wore scratched enamel pieces in their mouths for eight weeks. Brushing without toothpaste built "an organic-mineral protective membrane" on the surface, while brushing with an abrasive toothpaste "caused slight abrasion with microwear" (Kuroiwa et al., 1993, PMID 8448767). The authors added that "this roughness may contribute to the formation of dental plaque." That is the trade-off in two lines: polishing removes and reshapes the surface, deposition fills and smooths it. Any hydroxyapatite whitening claim is one or both of these, and neither reaches the inner color.

If your teeth have stayed yellow or grey through cleanings and whitening pastes, the cause may be intrinsic. Our guide to why some teeth will not whiten covers the causes and what a dentist can do about them.

Part 2

What does the systematic review say? Read both halves

Only one systematic review asks exactly this question: Tooth Whitening with Hydroxyapatite: A Systematic Review, published in Dentistry Journal in 2023 (Limeback, Meyer and Enax, 2023, PMID 36826195). It followed the PRISMA guidelines, searched PubMed, Scopus, Web of Science, SciFinder and Google Scholar, and found 279 titles. Seventeen studies met the inclusion criteria: 13 in the lab and the rest in people. The lab studies were graded for risk of bias with a tool called QUIN, and the human studies with the GRADE system.

Its conclusion, word for word:

"The results in vitro and in vivo were consistent in the direction of showing a statistically significant whitening of enamel... The evidence from in vitro studies is rated overall as having a low risk of bias. The evidence from in vivo clinical trials is supported by modest clinical evidence based on six preliminary clinical trials... the regular use of hydroxyapatite-containing oral care products effectively whitens teeth, but more clinical trials are required to support the preliminary in vivo evidence."

The last sentence is the one brands quote, and usually only its first half. Read the whole thing and it says two things at once: the authors conclude that hydroxyapatite products whiten, and they also say the human evidence is preliminary and needs more trials. Both halves are the authors' own words. Twelve of the 13 lab studies were rated low risk of bias. The human side rests on six preliminary trials.

Who wrote it

The paper's conflict of interest statement reads: "F.M. and J.E. are senior scientists and employees of Dr. Kurt Wolff GmbH & Co. KG." That company, in Bielefeld, Germany, makes hydroxyapatite toothpastes. The third author, Limeback, is at the University of Toronto, with no industry tie stated in this paper. Industry authorship does not make a review wrong, and the authors disclosed it. It does mean the only review on this exact question was co-written by people employed by a maker of the product type it assesses. You should know that when you weigh it.

This is not unusual for the hydroxyapatite literature. A separate, independent review on a different question, whether nano-hydroxyapatite prevents cavities, noted that "six studies were funded/published by the manufacturers of the tested products" and concluded that the evidence did "not allow for conclusive evidence on the efficacy of nHA" (Wierichs et al., 2022, PMID 35103837). That review is about cavities, not color, so it tells you nothing about whitening. It tells you that manufacturer funding is common across this field. Our overview of hydroxyapatite toothpaste studies goes through the wider research by topic.

One more limit: the review does not list, in its abstract, which six human trials it counted, and we did not match them one by one against the studies below. Part 3 looks at every human study on color that we could resolve ourselves.

Part 3

Does it work in people? The human studies

We found five studies in which people used a hydroxyapatite paste and someone recorded tooth color or stain. They differ a lot in design, and the design decides how much each one can tell you. The table puts them side by side.

Sources: PubMed records for PMIDs 21302741, 40508439, 32354134, 29109310, 22863133; checked 26 September 2026.

The placebo-controlled trial: no measurable change

The strongest design here is the oldest study. Raoufi and Birkhed at the University of Gothenburg enrolled 150 people with tooth discoloration and randomly assigned them to one of three toothpastes: one with hydroxyapatite, one with calcium peroxide, and a placebo, a fluoride toothpaste with no whitening ingredient. The trial was double-blind. Color was measured at the start and after 4, 8 and 12 weeks, on two different spectrophotometers, instruments that read a tooth's shade (Raoufi and Birkhed, 2010, PMID 21302741).

The result: "No significant improvement was observed after using the two spectrophotometeric methods." The authors concluded that the toothpaste containing hydroxyapatite or calcium peroxide "did not produce any reduction in tooth staining compared with a placebo fluoride toothpaste." Gum and plaque scores did improve significantly, in all three groups, which is what you would expect when 150 people brush carefully for 12 weeks under study conditions.

One finding from this trial is worth keeping in mind whenever you judge a whitening paste yourself. Participants in all three groups, including the placebo group, reported a subjectively lighter tooth color and less staining, though not to a significant degree. The instruments saw no change. People who expect whiter teeth tend to see them. That is not a criticism of anyone; it is why controlled trials use a placebo and an instrument.

The limits are real too. It is one trial, from 2010, and the abstract does not name the hydroxyapatite paste or its concentration. Formulas have changed since. It also found that the calcium peroxide paste did no better than placebo, so it is a result about those specific toothpastes, not a law of nature. But it is the only human study we found that combines a placebo group, blinding and an objective color instrument, and it found nothing measurable.

The studies that found an effect

Sozkes and colleagues gave a hydroxyapatite toothpaste to 50 smokers and 50 non-smokers for two weeks and scored stain with the Lobene index, a clinical scoring system in which an examiner grades the area and intensity of stain by eye (Sozkes et al., 2025, PMID 40508439). Scores fell significantly in both groups; in non-smokers, for example, the Approximal Plaque Index went from 32.5 to 16.5 (p<0.001). The reduction was more pronounced in smokers, who had more stain to begin with. There was no group using a different toothpaste, so the study cannot say how much of the change came from the hydroxyapatite, how much from the rest of the formula, and how much from brushing more carefully during a study.

Steinert and colleagues asked 46 people to use a zinc and hydroxyapatite toothpaste for four weeks and then fill in a questionnaire comparing it with their previous toothpaste (Steinert et al., 2020, PMID 32354134). People rated their "tooth color as whiter (p = 0.003)". No instrument measured color, and two of the six authors were employees of Dr. Kurt Wolff, the paste's maker. It tells you how people felt about the paste, which has value, but it is a perception result.

When hydroxyapatite was added to bleaching

Two studies looked at hydroxyapatite alongside peroxide bleaching. In Gomes and colleagues' in situ study, enamel fragments were fixed in volunteers' mouths and bleached with 35% hydrogen peroxide, with or without a nano-hydroxyapatite paste first. The whitening was the same: "The mean ΔE of the HP35% and nano-HAP groups did not differ statistically from each other" (Gomes et al., 2017, PMID 29109310). The nano-hydroxyapatite did make a difference to the enamel's hardness and mineral loss, which is what the study was mostly about. It did not add whiteness.

In Browning and colleagues' randomized trial, 42 people bleached with a 7% hydrogen peroxide gel for 14 days and used either a nano-hydroxyapatite paste (Renamel AfterBleach, made by Sangi) or a placebo paste after each session (Browning et al., 2012, PMID 22863133). The study's main question was sensitivity during bleaching. On color, the finding was one line: "Color change was equivalent." The peroxide did the whitening in both groups; the hydroxyapatite paste did not add to it.

Put the five together and the fairest summary is this: the only human study with an objective instrument and a placebo found no significant whitening; the studies with positive results had no comparison group for color or relied on how people felt; and when hydroxyapatite was combined with peroxide, it added nothing to the color change.

Part 4

How much whiter in the lab? The color measurements

Most of the positive evidence comes from lab studies on extracted human or cow teeth. These studies measure color with a colorimeter or spectrophotometer in the CIELAB system, which describes a color by lightness and two color axes. The difference between two measurements is reported as ΔE (delta E): the bigger the number, the bigger the color shift. Lab models isolate the effect of the mineral under controlled conditions, which is their strength. They leave out daily life in a real mouth, which is their limit.

Sources: PubMed records for PMIDs 35941677, 23841792, 19281109, 15348313, 32791529, 40277473; checked 26 September 2026.

What the numbers say

The clearest dose result is from Munich. Shang, Kaisarly and Kunzelmann brushed cow incisors with an experimental paste containing 10% or 1% nano-hydroxyapatite, or none, and exposed them to flowing liquid to mimic the forces in a mouth. After three applications the 10% paste reached a ΔE of 4.47, and the effect was "concentration-dependent"; under the microscope, hydroxyapatite crystals and clusters built up on the surface with each application (Shang et al., 2022, PMID 35941677). That is a picture of the optical route from Part 1: mineral settling on the tooth and changing how it reflects light.

The same group had tested other calcium phosphate formulas earlier, with a less tidy result. There were significant differences between materials, but "neither dose- nor time-dependent associations were found"; a 10% tricalcium phosphate formula gave a ΔE of 2.20, and a 20% zinc-carbonate-apatite formula the smallest shift, 0.91 (Jin et al., 2013, PMID 23841792). And in 2009, on 30 extracted premolars, nano-hydroxyapatite, hydroxyapatite nanocrystal and tricalcium phosphate groups all showed significant color change from baseline, which the authors called "promising alternatives to oxidizing bleaching agents" (Dabanoglu et al., 2009, PMID 19281109). These three Munich studies declared no industry funding.

A study from 2001 separated the polishing route from the optical one. Niwa and colleagues found that adding hydroxyapatite to a toothpaste did not change how it polished or abraded, but did increase whitening as the amount went up, and concluded that the "whitening was not due to their polishing effect on tooth surface" (Niwa et al., 2001, PMID 15348313). The paper included color readings in volunteers; its abstract does not say how many.

Two newer lab studies come from authors employed by Dr. Kurt Wolff, the hydroxyapatite toothpaste maker in Bielefeld. A hydroxyapatite gel, applied by finger, produced a mean ΔE of 5.4 after one cycle on enamel samples (Sarembe et al., 2020, PMID 32791529). And in a stain-removal model on human enamel, a hydroxyapatite toothpaste removed significantly more stain than a blue covarine toothpaste after 30 seconds of brushing, while after 180 seconds the two were "comparable" (Enax et al., 2025, PMID 40277473). The fourth author of that study had received earlier funding from the same company, as the paper discloses.

What the lab cannot tell you

None of these studies measured the inner color of a tooth changing. They measured how the surface looked after mineral was deposited or stain was removed. None ran for months in real mouths with food, drinks and saliva working on the surface between brushings. And the ΔE numbers come from different models, so a 4.47 in one study and a 5.4 in another are not directly comparable. What the lab work shows well is the mechanism: hydroxyapatite can settle on enamel and change how it reflects light. Whether that change is large and lasting enough for people to notice day to day is the question the human trials have not settled.

Part 5

Hydroxyapatite or peroxide: which one changes tooth color?

Peroxide works on a different level. Hydrogen peroxide, or carbamide peroxide, which releases it, passes through enamel into the dentin and breaks down color molecules there. That is why it can change a tooth's own shade and not only its surface. A lab study of a 6% hydrogen peroxide product tested both at once: stain removal from tea-stained discs and the color of whole extracted teeth. The product gave "significantly more extrinsic stain removal (p<0.0001) and an increase in tooth whiteness (p<0.05)" (Joiner and Thakker, 2004, PMID 14738831). The same study measured the peroxide reaching the pulp chamber at 0.44 mM, which the authors put at "over 3000 times below the concentration reported to cause pulpal enzyme damage." Joiner worked for Unilever Oral Care, which made the product.

That two-track effect, surface stain plus inner color, is what no hydroxyapatite study in this article shows. When the two were combined, the peroxide did the whitening. In a lab study on 15 extracted third molars, both a 6% hydrogen peroxide home bleaching product and the same product with added nano-hydroxyapatite improved whiteness compared with untreated teeth; the added nano-hydroxyapatite better preserved the enamel's prism structure under the microscope (Monterubbianesi et al., 2021, PMID 34199770). The whitening came from the peroxide in both groups. Our comparison of whitening strips and a remineralizing gum covers the peroxide side in more detail.

The EU limit on hydrogen peroxide

In the EU, how much peroxide you can buy over the counter is set in law. Council Directive 2011/84/EU of 20 September 2011 records the scientific committee's view that "a maximum concentration of 0,1 % of hydrogen peroxide present in oral products or released from other compounds or mixtures in those products is safe." Its annex sets two tiers. For "oral products, including mouth rinse, tooth paste and tooth whitening or bleaching products": "≤ 0,1 % of H₂O₂, present or released". For "tooth whitening or bleaching products" above that: "> 0,1 % ≤ 6 % of H₂O₂, present or released", with the condition "to be only sold to dental practitioners. For each cycle of use, first use by dental practitioners... or under their direct supervision if an equivalent level of safety is ensured. Afterwards to be provided to the consumer to complete the cycle of use. Not to be used on a person under 18 years of age."

So in the EU, a toothpaste or strip sold straight to you carries at most 0.1% hydrogen peroxide, present or released. Anything stronger, up to 6%, goes through a dentist. Hydroxyapatite has no whitening limit of this kind, because it is not a bleach. It is regulated for particle safety instead: Regulation (EU) 2024/858, in force since 4 April 2024, permits hydroxyapatite (nano) up to 10% in toothpaste and 0.465% in mouthwash, for rod-shaped, uncoated particles, based on SCCS opinion SCCS/1648/22. A later SCCS opinion, SCCS/1677/25, adopted on 26 June 2025, assessed higher levels as safe for a different particle specification; as of 26 September 2026 that is an opinion, not law. Neither covers chewing gum. Our article on whether nano-hydroxyapatite is safe goes through those opinions, and our guide to hydroxyapatite mouthwash covers the rinse limit and the brands that sell one.

In the US: cosmetic or drug

In the US, the FDA decides whether a product is a cosmetic or a drug by its intended use, which it reads from "claims stated on the product labeling, in advertising, on the Internet, or in other promotional materials." The anticavity rules for toothpaste recognize three actives: sodium fluoride, sodium monofluorophosphate and stannous fluoride. Neither peroxide nor hydroxyapatite is on that list, so a toothpaste making only an appearance or stain claim is generally sold as a cosmetic. The FDA has issued warning letters to smaller brands, Dr. Brite in November 2024 and Health and Natural Beauty USA Corp. (SprinJene) in July 2025, citing hydroxyapatite wording such as "remineralizes" and "restores" as unapproved drug claims. Whitening framed as surface stain removal is cosmetic territory.

Part 6

What do hydroxyapatite toothpaste brands claim about whitening?

We read the product pages and full ingredient lists of eight hydroxyapatite toothpastes sold with a whitening claim, on 26 September 2026. For each, the table shows the whitening wording in the brand's own words, the other cleaning or stain-lifting ingredients on the same list, and where hydroxyapatite sits. Cosmetic ingredient lists are generally ordered from the largest amount to the smallest, so position gives a rough idea of how much of each ingredient is present.

Brand wording and ingredient order from each brand's own product, science or FAQ page, checked 26 September 2026. Positions count from the first listed ingredient.

The pattern on the labels

Every product in the table lists at least one other ingredient that cleans or lifts stain alongside the hydroxyapatite. Silica or hydrated silica appears on all eight brands' lists. Calcium carbonate appears on three, baking soda on three, enzymes on one. On every list, at least one of these cleaning agents comes before the hydroxyapatite. As the Joiner review in Part 1 notes, the abrasive system is the main whitening ingredient in whitening toothpaste generally. None of this means the hydroxyapatite does nothing; the Niwa study found an effect beyond polishing. It means a tube's whitening result cannot be credited to the hydroxyapatite alone, and no study we found tested any of these eight formulas for color in people.

Several brands say this themselves. Boka's copy credits "high-cleaning silica" and scopes its whitening asterisk to surface stains. Lumineux describes its whitening as "visibly smoothing enamel and gently lifting surface stains." Twice credits its enzymes and states in its FAQ: "Happy Mint uses enzymes in a peroxide-free formula. Our Whitening Strips are a separate hydrogen peroxide treatment." Our Lumineux toothpaste review covers that brand in full.

Two brands that label each ingredient, and disagree

Dr. Jen and Cocofloss both print a short function next to each ingredient, which makes them easy to compare. On Dr. Jen's Super Paste, calcium carbonate "helps whiten teeth" and silica "polishes teeth", while nano-hydroxyapatite "strengthens enamel". Dr. Jen's eggshell-derived paste labels its hydroxyapatite differently: "Nano Hydroxyapatite derived from Eggshell (strengthens enamel and whitens teeth)". Cocofloss labels the hydroxyapatite in Cocoshine as the "mineral that strengthens, whitens, and reverses sensitivity," with silica listed as a polish and baking soda as "a natural surface stain remover." So two brands, reading the same ingredient, assign whitening to different parts of the formula.

The evidence each brand points to is worth a look too. Dr. Jen's product page links a study with the claim that the paste is "clinically proven to outperform fluoride alone." That study measured the microhardness of artificial caries lesions on extracted teeth after a 7% nano-hydroxyapatite and fluoride paste (Ebadifar et al., 2017, PMID 28413590); it did not measure color. Cocofloss footnotes its one-week claim: "After 1 week's worth of brushing for a single tooth, the Delicious Mint toothpaste formulation whitened by a maximum of 1.96 VITA® tooth shades (Intertek, 2023)." That is a brand-commissioned lab test by a testing firm, on a single tooth, not a published human trial, and the footnote says so. Cocofloss also publishes an abrasivity figure for Cocoshine, RDA 37, which it calls a low-abrasion polish. Our Cocofloss toothpaste review goes through Cocoshine in detail.

If you are choosing a hydroxyapatite toothpaste for reasons beyond color, our ranking of the best hydroxyapatite toothpastes compares the pastes that publish a percentage.

Part 7

How to judge a hydroxyapatite paste for brighter teeth, in five steps

If a brighter look is one of your reasons for buying a hydroxyapatite toothpaste, these steps keep your expectations in line with the evidence.

• Work out which kind of color you have. If your teeth have picked up stain from coffee, tea or smoking and looked whiter after your last professional cleaning, much of the color is on the surface, and a stain-removing paste can help. If they look yellow or grey straight after a cleaning, the color is mostly inside the tooth, and no toothpaste, hydroxyapatite or otherwise, will change it much. Your dentist can tell you which it is.
• Read the whole ingredient list. Look for silica, hydrated silica, calcium carbonate, sodium bicarbonate, enzymes such as papain or bromelain, and phosphates such as pyrophosphate or hexametaphosphate. These clean stain on their own. A paste can be a good stain remover because of them; know which ingredient you are paying for.
• Brush for the full time. In the lab comparison by Enax and colleagues, the hydroxyapatite paste's lead over a blue covarine paste at 30 seconds had gone by 180 seconds. Short brushing favors some formulas; full brushing gives each paste a fair chance.
• Judge with a photo, not a feeling. In the 12-week Raoufi trial, people in all three groups, placebo included, felt their teeth looked lighter while two instruments measured no significant change. Take a photo in the same daylight at the start and after a few weeks, and compare.
• If you want a shade change, talk to a dentist about peroxide. A shade change needs peroxide, and in the EU anything above 0.1% hydrogen peroxide goes through a dentist. Adding hydroxyapatite during bleaching did not change the color result in the two studies that tested it.

For the wider question of whitening without wearing enamel down, including abrasivity and how often to bleach, see our guide on how to whiten teeth without damaging enamel.

Part 8

Where a hydroxyapatite gum fits: not as a bleach

Since we make a hydroxyapatite gum, here is where it stands on this question, in plain terms. Minvelle is a sugar-free chewing gum with xylitol and nano-hydroxyapatite: 5.7 mg of nano-hydroxyapatite per 1.9 g piece, printed on the box, plus 817 mg of xylitol. You chew one piece a day after a meal, between brushings, for at least 20 minutes. The gum contains no peroxide and does not bleach teeth.

The research picture for gum is simple. We found no PubMed-indexed study that tested a hydroxyapatite chewing gum for tooth color. The one whitening-gum trial we found used a different active, sodium metaphosphate, and used a hydroxyapatite pellet only as the stained surface being cleaned (Makino et al., 2019, PMID 31172873). That is a study about sodium metaphosphate, not about hydroxyapatite, and we do not cite it for our gum.

What the gum cannot do

• It does not bleach teeth. It contains no peroxide and does not reach the inner color of a tooth.
• It does not replace brushing or your toothpaste. Keep brushing twice a day with the paste you choose.
• It does not fill a cavity or regrow lost enamel. That is a job for a dentist.
• 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 hydroxyapatite whitening pastes do well

An article built on the studies reads as skeptical, so here is the other side, from the same sources. The lab evidence that hydroxyapatite can change how the enamel surface looks is consistent: the one systematic review rated 12 of its 13 lab studies at low risk of bias, and the independent Munich group found a dose-dependent effect with no industry funding. Stain scores fell in the two-week study of smokers and non-smokers. In a head-to-head lab test, a hydroxyapatite paste removed stain faster than a blue covarine paste.

The brands, too, mostly scope their claims to what the evidence can carry. Lumineux and Boka describe their whitening as surface stain removal, and both, like Twice, say their pastes contain no peroxide. Boka puts an asterisk on the word whitening and defines it. Twice separates its enzyme toothpaste from its peroxide strips in plain words. Cocofloss footnotes its one-week claim to the test it comes from and publishes an abrasivity figure. Dr. Jen and Cocofloss print a function next to every ingredient, which lets you see what each one is for. For a stain-prone mouth that wants a peroxide-free paste, these are reasonable products, and a hydroxyapatite paste is a sound daily toothpaste for reasons that have nothing to do with color.

The verdict

Does hydroxyapatite whiten teeth? In one paragraph

Hydroxyapatite can make teeth look a little brighter at the surface, by helping lift stain and by depositing mineral that reflects light. It does not bleach and does not change a tooth's inner color. The lab evidence for the surface effect is consistent. The human evidence is thin: the only systematic review, co-written by two employees of a hydroxyapatite toothpaste maker, calls it modest and preliminary, and the one placebo-controlled trial with color instruments found no significant change over 12 weeks. Every whitening paste we checked also contains another cleaning agent that removes stain on its own. If surface stain is your problem, a hydroxyapatite paste is one reasonable choice among stain-removing pastes. If you want a different shade, the ingredient that does that is peroxide, and above 0.1% in the EU it comes through a dentist.

Studies, brand pages and regulatory documents checked on 26 September 2026 from the sources below. If a brand changes its label or a new trial is published, tell us and we will update this guide.

Questions, answered

The things people actually ask