What is in the gel, what each part does, and what the published research says about it.
None of these studies tested our gel. That is why the guarantee is measured on your teeth.
Our documented case · 8 steps lighter in 12 days
The thirty second version, so the rest of the page makes sense.
Coffee, tea, red wine and snus leave colour molecules on and in the outer layer of your teeth.
Those molecules are long chains. They swallow blue light, so what bounces back looks yellow.1
Whitening cuts the chains into short pieces. The yellow fades. Nothing is scraped or sanded off.
One lifts the stain, one looks after the enamel, one holds it all in place for ten minutes. Tap any of them for the research.
PAP (phthalimidoperoxycaproic acid) does the bleaching itself, without releasing hydrogen peroxide. It was first made to lift tea, coffee and grass stains out of fabric at low temperatures.4 Old, well studied, a little boring. Exactly what you want in your mouth.
Shades lighter after one 20 minute session. On placebo: 0.01.
2.26Bizhang 2017 · 40 adults, double blind · another brand's gel, manufacturer fundedPeople with sensitivity recorded by the examiner after PAP. On placebo: 3 of 20.
0of 20Same trial · people with sensitive teeth were not includedEnamel erosion in lab tests of PAP gels. Hardness stayed the same or rose slightly.
NonePascolutti 2021, Boruga 2025 review · lab studies on real enamel
Hydrogen peroxide is small enough to travel through the tooth to the nerve, the route linked to the "zing".12 At home in the EU it is capped at 0.1%.3
Llena 2026, lab study on extracted teeth, no external funding.6 Ours is PAP12%.
Most kits say "PAP". Almost none say how much.
Both results are lab studies on extracted teeth, testing other makers’ gels, not ours.
Whether you buy from us or elsewhere, ask for the percentage.
Two separate lab studies with different set-ups (Llena 2026, Palandi 2026), not a head-to-head test, and neither tested our gel.
Enamel is mostly hydroxyapatite. In oral care it is added as tiny particles that settle into the small gaps and open channels that let cold, and whitening, reach the nerve.10
Same whitening gel with or without 2% hydroxyapatite. Equally whiter, significantly less sensitivity with it.
60 peopleVano 2015 · randomised, 9 month follow-up · a 6% peroxide gel11Days of sensitivity when a hydroxyapatite paste was used after whitening, against a paste without it.
36 vs 76Browning 2012 · 42 people, randomised · colour change the same12Clinical trials pooled: hydroxyapatite cut sensitivity more than placebo and more than fluoride.
44 trialsLimeback 2023 · two authors work for a hydroxyapatite toothpaste maker13Most of this research is on toothpaste, or used next to a peroxide gel. We have not published how much hydroxyapatite is in our gel yet.
Whitening works while the gel touches the tooth. The tray holds it against both rows at once for exactly ten minutes, beeps, and switches itself off.
Violet light alone, no gel, lightened teeth. Still measurable a year later.
ΔE 2.66Lopes 2024 · 40 adults, randomised · clinic lamp, about 50 min per visit14Trials pooled: violet light made whitening gel work better, with no extra sensitivity.
3 trialsBessa 2025 · the authors call the evidence moderate15These used clinic lamps around 400 nm. We have not published our tray's wavelength, so we do not claim it does what a clinic lamp does.
Where each ingredient does its job. Filmed by creators using the kit exactly as it ships.
Clean, dry teeth let the gel grip the surface.
A thin layer on the front of each tooth, about a quarter of a pen. Thin is right.
PAP + hydroxyapatiteThe timer starts. After ten minutes it beeps and switches off. Rinse with lukewarm water.
LED trayHold the shade card to your teeth and take a photo. That is your own study.
Shade cardCreator films are paid collaborations.
The questions we get most, answered with the research above.
In lab studies on real enamel, PAP gels caused no erosion, and hardness stayed the same or rose slightly.89 The hydroxyapatite in the gel is the same mineral enamel is made of.
We cannot promise it never will. The sharp zing most people remember is linked to hydrogen peroxide, and there is none in our gel.2 If your teeth are already sensitive, use mode 2 and pause a day if you need to.
Not at the right strength. In the lab, 12% PAP beat dentist-strength peroxide on whiteness. A kit that does not state its strength gave no significant whitening in a separate study.619
It is a cosmetic, registered under the EU Cosmetics Regulation with a safety assessment by a qualified assessor. Cosmetics are registered, not "approved" by a medicines agency.3
No. Whitening only works on natural enamel. Fillings, crowns and veneers keep their colour, so ask your dentist if you have visible work at the front.
Usually months. Coffee, tea, red wine and snus bring the colour back faster. A few sessions with a Gel Refill keeps it there.
A twenty step shade card, built on the method dentistry has used since 1956:16 hold your tooth against a graded reference, note the match, and do it again twelve days later.
If the match has not moved by day twelve, the Starter Kit is refunded.
For the curious, and for your dentist. What each one tested and who paid for it. None tested a WeSmile product, and we funded none of them.
| Study | Design | Tested | Main result |
|---|---|---|---|
| PAP | |||
| Bizhang 20175J Appl Oral Sci | Double blind, placebo controlled, 40 adults | One 20 min PAP application, another brand | 2.26 shades vs 0.01 on placebo. No recorded sensitivity on PAP. Manufacturer funded. |
| Llena 20266J Funct Biomater | Lab, 57 extracted incisors | 12% PAP vs 37.5% HP vs 35% CP | Whiteness index 8.82 vs 4.48 vs 4.16. No external funding. |
| Qin 20197Composites Commun | Lab formulation study | PAP and HP at matched strengths | 5% PAP ≈ 3% HP, 12% PAP ≈ 8% HP. |
| Pascolutti 20218Dent J | Lab, 30 enamel slabs | PAP gel vs 6% HP, six 10 min sessions | 8.13 vs 4.86 shades. No erosion, hardness up. |
| Manso 20219in Dent J review | Lab, 20 molars, 56 days | Prolonged PAP use | Hardness 340.08 to 347.79 N/mm², no demineralisation. |
| Grillon 20249in Dent J review | Lab, 80 bovine incisors | Up to 200 min exposure | Colour change with stable pH, described as non erosive. |
| Khan 20249in Dent J review | Lab, 60 premolars | Dentine after PAP | Nano hardness up 15%. |
| Khan 20239in Dent J review | Lab, 72 composite samples | Fillings after PAP | Roughness down 12%, hardness up 20%. |
| Palandi 202619Lasers Med Sci | Lab, 108 tea-stained bovine blocks | Commercial PAP+ kit (strength not stated) ± LED vs 10% HP | PAP+ not significantly different from no treatment, even at twice the recommended use. No enamel damage in any group. |
| J Dent 202617J Dent | Lab, 28 days | PAP gel vs 10% CP | Whitening by day 14, alkaline pH, enamel surface unchanged. |
| Hydroxyapatite | |||
| Vano 201511Int J Dent Hyg | Randomised, examiner blinded, 60 people | 6% HP gel with vs without 2% nano-HA | Same whitening, significantly less sensitivity with HA. |
| Browning 201212J Esthet Restor Dent | Randomised, 42 people | Nano-HA paste after 7% HP whitening | 36 vs 76 days of sensitivity. Same colour change. |
| Limeback 202313Biomimetics | Meta-analysis, 44 trials | HA oral care vs placebo and fluoride | Sensitivity down 39.5% vs placebo, 23% vs fluoride. Two authors employed by an HA toothpaste maker. |
| Vano 201418Quintessence Int | Double blind, 105 people | 15% nano-HA toothpaste vs fluoride vs placebo | Significantly less sensitivity at 2 and 4 weeks. |
| Light | |||
| Lopes 202414Front Dent Med | Randomised, 40 people, 12 months | Violet LED alone vs violet LED + 37% CP, in clinic | ΔE 2.46 at 24 h and 2.66 at 12 months with light alone. Gel + light did more. Low sensitivity in both. |
| Bessa 202515Lasers Med Sci | Meta-analysis, 3 trials | CP with vs without violet light, in clinic | Better colour change with light, no difference in sensitivity. Moderate certainty. |
| Background | |||
| Kwon 20151J Esthet Restor Dent | Review | How whitening works | Whitening agents diffuse into the tooth and break down stain molecules. |
Illustrations on this page are drawings of a mechanism, not photos or results. WeSmile products are cosmetics, registered under the EU Cosmetics Regulation and notified in the CPNP.
Twelve evenings, a photo against the shade card before each one. Either the card moves, or the Starter Kit is refunded.
