How to Whiten Teeth: What Works and What Is Hype (2026)

Dental Science  ·  Evidence Guide

How to Whiten Teeth: What Works and What Is Hype

// The short answer

Peroxide-based whitening strips are the best-evidenced OTC option: 6% hydrogen peroxide strips used twice daily for 2 weeks produce measurable, lasting color improvement in multiple meta-analyses.1 PAP strips are a well-supported sensitivity-free alternative. Whitening toothpaste removes surface staining but does not change underlying tooth color. Charcoal does not work and may cause harm.

Teeth whitening is one of the most searched cosmetic topics online, and the market is full of competing claims. Some of them are backed by genuine clinical data. Many are not. This guide cuts through the noise: what the peer-reviewed research says about every major whitening method, how sensitive teeth respond, what the enamel safety evidence actually looks like, and which trending options are mostly marketing.

Habib A MuflihFounder of MAXXING | Last updated: June 2026 | 12 min read Informational guide only. Not dental or medical advice. For persistent discoloration, gum disease, or tooth pain, see a licensed dentist. Supports-language throughout.
-2.3 delta-b*
Yellowness reduction with 6% HP strips over 2 weeks
Gerlach et al. 2009, 7-RCT meta-analysis
18 mo
Color retention above pre-treatment baseline after HP strip use
Gerlach et al. 2007, clinical trial
~20%
Tooth sensitivity rate with 6% HP strips in clinical trials
Gerlach et al. 2009
<3%
Sensitivity rate reported with PAP-based whitening in available studies
Today's RDH, 2023 review
// What's in this guide
  1. Why teeth yellow in the first place
  2. Peroxide whitening strips: the evidence
  3. PAP: the sensitivity-free alternative
  4. Whitening toothpaste: what it can and cannot do
  5. Professional bleaching: when it is worth it
  6. All methods compared
  7. Enamel safety: the honest picture
  8. What is hype: charcoal, oil pulling, LED lights
  9. Keeping your results longer
  10. FAQ

01Why teeth yellow in the first place

Before picking a whitening method, it helps to understand what kind of staining you are dealing with. Not all discoloration responds to the same treatments, and mismatched approaches waste money and time.

Researchers classify tooth discoloration into three main types.17 Extrinsic staining sits on the tooth surface and in the acquired pellicle (a thin protein film). Coffee, tea, red wine, tobacco, and certain medications deposit chromogens (color-carrying molecules) that bind to pellicle proteins or directly to enamel. Extrinsic staining responds well to both abrasion (whitening toothpaste) and peroxide bleaching. Intrinsic staining originates within the dentin, either from systemic causes during tooth development (tetracycline, fluorosis) or from pulpal bleeding and degradation after tooth trauma. This type responds poorly to OTC whitening products. Internalized staining is extrinsic stain that has entered the enamel through micro-cracks, and it sits somewhere between the two in terms of how well bleaching works.

The practical implication: if you have deep or uneven discoloration that does not improve after a full treatment course with strips, the most useful next step is a dentist visit to identify the stain type before spending more on OTC products. Understanding your overall appearance and confidence goals can help frame where dental care fits into the bigger picture.

// Key takeaway

Surface staining from food, drinks, and tobacco responds well to peroxide and abrasive whitening. Deep intrinsic staining from tetracycline or fluorosis does not, and OTC products are unlikely to make a meaningful difference. If standard treatment has not worked, see a dentist to identify the type.

02Peroxide whitening strips: what the evidence says

Hydrogen peroxide (HP) strips are the most extensively studied OTC whitening method. The mechanism: HP penetrates enamel and dentin, generating free radicals that oxidize the chromophore molecules responsible for yellow and brown discoloration. Unlike abrasion-based methods, peroxide actually changes tooth color rather than just removing surface deposits.

A 2009 meta-analysis pooling seven RCTs (148 treated participants) of 6% HP strips used twice daily for 30 minutes found a mean yellowness reduction of -1.6 units after one week and -2.3 units after two weeks, both highly significant (p < 0.001).1 Color change continued without plateau across 6 weeks in a separate placebo-controlled trial.3 A 2024 network meta-analysis of 37 studies confirmed that 6% HP strips with extended use achieve greater whitening than lower concentrations, with overall satisfactory outcomes across OTC products.9

Higher concentration strips (10% and 14% HP) whiten faster. A randomized trial found 10% HP strips achieved results in one week equivalent to 6% HP over two weeks.4 A 14% HP formulation in a controlled 6-week trial showed yellowness reduction of -4.1 and brightness gain of +3.2 versus placebo at 6 weeks, with no increase in adverse events with extended treatment.6

How do strips compare to professional tray bleaching? A 2016 meta-analysis of 8 RCTs found no significant difference in overall whitening between OTC strips and 10% carbamide peroxide gel. Strips showed superior yellowness reduction and lower gingival irritation rates.10 A 2020 systematic review and meta-analysis of 20 RCTs found supervised bleaching did produce statistically greater spectrophotometer readings but, importantly, the color difference was often undetectable by unaided human eyes. Strips also showed lower sensitivity risk (RR = 0.78).2

How long does whitening last? A clinical trial following participants for 18 months found that both HP strips and sodium percarbonate film maintained yellowness reduction significantly above pre-treatment baseline throughout the full follow-up period. Some color rebound from the immediate post-treatment peak is normal and expected.8

// Key takeaway

Peroxide whitening strips are the best-evidenced OTC whitening method. A full 2-week course of 6% HP strips produces real, measurable color change that holds for at least 18 months. Results are statistically comparable to professional tray bleaching, with lower sensitivity and lower cost.

03PAP whitening: the sensitivity-free alternative

PAP stands for phthalimidoperoxycaproic acid (CAS 128275-31-0). It is a synthetic peroxy acid that whitens teeth through a fundamentally different chemistry than hydrogen peroxide. Where HP generates free radicals that oxidize chromophores, PAP acts through Baeyer-Villiger oxidation, targeting the conjugated double bonds in stain molecules directly, without producing reactive oxygen species (ROS).12

That distinction matters for enamel and sensitivity. A 2021 laboratory study comparing PAP+ (12% PAP with nano-hydroxyapatite and potassium citrate) against 6% and 35% HP found: PAP produced no enamel erosion, while HP formulations produced measurable erosion of 0.10 to 0.11 mm. PAP actually increased enamel microhardness by +12.9 VHN, while 35% HP reduced it by -94.28 VHN and 6% HP reduced it by -62.22 VHN. In terms of shade improvement, PAP achieved approximately 70% more shade units than 6% HP on polyphenol stains in this protocol.11

A 2026 in vitro study compared PAP directly against professional-grade 37.5% HP and 35% carbamide peroxide on extracted human incisors. Lightness gain: HP = 7.19, PAP = 7.11, carbamide peroxide = 4.43. PAP delivered equivalent lightness improvement to high-concentration professional HP while producing fewer enamel surface changes under scanning electron microscopy.14

A 2025 systematic review of hydrogen-peroxide-free color correctors (including PAP) covering 6 studies found mean color changes of 2.8 to 3.5 delta E units, surpassing the clinical perceptibility threshold of 2.7. Sensitivity incidence was below 3%.15

The honest caveat: most PAP data comes from in vitro studies. Human clinical trials are smaller and fewer than the peroxide evidence base. The mechanism and enamel-safety profile are well-documented; long-term multi-center clinical RCTs are still being conducted. PAP is a genuinely different and promising chemistry, not just a marketing rebrand. It is a particularly useful option for people with sensitive teeth, those in countries where OTC HP concentration is restricted (the EU caps OTC HP at 0.1%), and for regular maintenance use where minimizing enamel exposure over time matters.

// Key takeaway

PAP whitens through different chemistry than peroxide, with no enamel erosion or microhardness loss in lab studies. Sensitivity rates below 3% make it the better choice for sensitive teeth. The efficacy evidence is solid in vitro; large human clinical trials are still maturing. It is not hype, but it is not as extensively studied as HP strips either.

04Whitening toothpaste: what it can and cannot do

Whitening toothpastes work primarily through abrasion. Mild abrasive particles (silica, calcium carbonate, baking soda) scrub surface stains off the tooth. Some also contain blue covarine, an optical brightener that deposits on enamel and creates an immediate whitening illusion by shifting light reflection. A small number include low-level peroxide or hydroxyapatite to add a modest bleaching component.

The important limitation: whitening toothpaste removes extrinsic surface staining and can improve perceived brightness, but it does not penetrate enamel to oxidize intrinsic color the way peroxide bleaching does. This means it will not change your underlying tooth shade. A 12-week clinical trial comparing 6% HP strips against two whitening dentifrices found the strips produced highly significant reductions in yellowness and redness at week 2, and maintained significant superiority over either toothpaste at 12 weeks. Neither toothpaste differed significantly from the other.7

A separate 3-week RCT comparing strips, a paint-on gel, and whitening dentifrice found: strips achieved delta-b* of -2.53 (p < 0.0001), paint-on gel -0.21, dentifrice -0.06. Only strips produced significant color improvement.5

What toothpaste is genuinely useful for: daily maintenance of whitening results, preventing surface stain buildup, and a modest brightness boost if intrinsic color change is not the goal. The abrasivity matters. Look for a low-to-moderate RDA (Relative Dentin Abrasivity) rating, ideally under 150. Overly abrasive pastes used twice daily for years can contribute to enamel wear.

Nano-hydroxyapatite (nHAp) toothpastes deserve a mention: a 2023 systematic review found regular use of hydroxyapatite-containing oral care products supports whitening through two mechanisms: filling microscopic enamel defects to reduce light scatter, and depositing an opaque mineral layer that blocks yellow dentin reflection. It is an evidence-backed addition to a maintenance routine, particularly for people who want to avoid peroxide entirely.16

05Professional bleaching: when it is worth it

In-office bleaching uses 25% to 40% hydrogen peroxide applied by a dental professional, often with gingival protection and sometimes with light or laser activation. The main advantage is speed: results are visible within one session. The drawbacks are cost, higher sensitivity risk with concentrated HP, and a tendency toward faster color rebound without ongoing at-home maintenance.

A 2024 umbrella review of 28 systematic reviews covering 416 RCTs found no significant overall difference in color change between in-office and at-home bleaching techniques (p = 0.95). Sensitivity risk and intensity were also comparable (p = 0.85). Light activation did not increase efficacy. Lower concentrations over extended periods produced similar results to high concentrations applied briefly.13

A 2021 triple-blinded RCT (n = 130) found at-home 10% carbamide peroxide actually produced superior color improvement to in-office 35% HP on multiple spectrophotometric parameters.19

Where professional treatment adds clear value: deep or uneven intrinsic staining where a dentist can also assess whether bleaching is appropriate at all; pre-event whitening where speed matters more than cost; and as the starting point for a combined protocol. A 2025 RCT with 24-month follow-up found that combining in-office sessions with intensive at-home touch-up produced significantly better long-term color stability than in-office treatment alone.20

If you are considering professional treatment, go to a licensed dentist rather than an unlicensed cosmetic salon. High-concentration HP applied without professional assessment and gingival protection carries real risk of soft-tissue burns and pulp irritation.

06All whitening methods compared

Table 1 - Whitening method comparison by mechanism, evidence, and typical outcome
Method Active mechanism Evidence base Typical color change Sensitivity risk Enamel impact
Peroxide strips (6% HP) Free-radical oxidation of chromophores Multiple meta-analyses, 20+ RCTs 2+ shades in 2 weeks, lasts 18+ months ~20% (mild, transient) Transient microhardness change; recovers by day 7
Peroxide strips (10-14% HP) Free-radical oxidation Multiple RCTs Faster onset; equivalent or superior 2-week result Similar to 6%; higher at 14%+ Slightly greater transient effect vs 6%
PAP-based strips Baeyer-Villiger oxidation; no free radicals In vitro studies; 1 RCT; systematic review 2025 Comparable lightness gain to HP in vitro <3% in available studies No erosion; microhardness maintained or improved
Whitening toothpaste Abrasion of extrinsic stain; optical brighteners Multiple RCTs vs strips (inferior) Minimal intrinsic change; removes surface deposits Low Risk of wear with high-RDA formulas long-term
Nano-hydroxyapatite toothpaste Mineral layer deposit; enamel defect filling Systematic review 2023; 4 in vivo studies Modest brightening; remineralization benefit Very low Supportive; no erosion risk
Professional in-office (25-40% HP) High-concentration free-radical oxidation Umbrella review 28 SR, 416 RCTs Rapid onset; comparable final result to at-home Moderate to high (especially 35%+) Greater immediate effect; higher ROS burden
Carbamide peroxide tray (at-home) Slow-release peroxide to enamel Extensive RCTs; comparable to strips Strong long-term results with consistent use Lower than in-office HP; similar to strips Comparable to equivalent HP concentration
Color change ratings are based on clinical trial outcomes in populations with typical extrinsic and mild intrinsic staining. Results vary by individual stain type, depth, baseline tooth shade, and adherence. PAP in vitro data is not directly equivalent to clinical human trial data.

07Enamel safety: the honest picture

Enamel safety is the most common concern with whitening, and the data is more nuanced than either "it is completely safe" or "it destroys your teeth." Both of those framings are wrong.

At OTC concentrations, the evidence supports cautious confidence. An in vitro study examining 5.3% HP strips (including at 5x the recommended exposure) found no deleterious effects on enamel surfaces, no change in fracture susceptibility, and no significant surface changes under electron microscopy.21 A separate microhardness study found that all bleaching treatments caused measurable hardness reduction at 24 hours, but by day 7 all specimens had recovered to normal hardness through remineralization, with no significant differences between treated and control groups at day 7.22

At higher concentrations and prolonged exposure, the picture changes. An in vitro microCT study found 10% carbamide peroxide applied 8 hours/day for 15 days caused demineralization extending 50 micrometers below the enamel surface, prompting the authors to recommend careful consideration in patients susceptible to caries and tooth wear.23 At 35% carbamide peroxide, demineralization extended to 250 micrometers in a separate in vitro study.24

The mechanism behind sensitivity is separate from enamel erosion. A 2021 mechanistic study confirmed that HP bleaching gels induce pain conduction in dental pulp stem cells via intracellular reactive oxygen species: ROS elevation triggers calcium influx through TRPA1 channels, leading to ATP release and upregulation of inflammatory cytokines IL-6 and TNFa. This pathway was concentration-dependent, with 40% HP causing proportionally greater cellular effects than 15% HP. Pre-treatment with an antioxidant significantly reduced damage, confirming ROS as the primary causal factor.18

Practical guidance from the evidence:

  • Follow the manufacturer protocol. The "total peroxide dose" across the treatment period, not concentration alone, governs both efficacy and risk. More is not always better.
  • Do not use whitening products on damaged enamel, active cavities, or gum disease without a dentist clearing you first. These conditions change how peroxide penetrates and how much tissue is exposed.
  • Fluoride after whitening supports remineralization. A study found fluoride-enhanced carbamide peroxide caused remineralization of demineralized enamel without reducing whitening efficacy.25
  • Sensitivity that persists beyond 3 days post-treatment is worth discussing with a dentist. Transient sensitivity is expected and documented; persistent or sharp pain is not.
// Key takeaway

OTC whitening strips at recommended concentrations and durations do not cause permanent enamel damage in clinical studies. Microhardness effects are transient and recover within a week. Risk increases significantly at high concentrations, with overuse, and in people with compromised enamel. For anyone with active dental issues, see a dentist before starting any whitening.

08What is hype: charcoal, oil pulling, and LED lights

Some of the most heavily marketed whitening approaches have the weakest evidence. A straight look at each:

Activated charcoal toothpaste

No published clinical trials show charcoal toothpaste to be an effective whitening agent. A 2021 review of OTC whitening products found charcoal products show no significant whitening efficacy in available studies.26 The American Dental Association has not awarded its seal to any charcoal toothpaste. The concern is not just inefficacy: charcoal is often highly abrasive, and most charcoal toothpastes are fluoride-free. Regular use of a highly abrasive, fluoride-free paste may contribute to enamel wear and increased cavity risk over time. The black color is visually striking and photographs well. That is largely what you are paying for.

Oil pulling

Oil pulling (swishing coconut or sesame oil for 15 to 20 minutes) has some evidence for modest reduction in oral bacteria and plaque, which might help with gum health. It has no credible clinical evidence for intrinsic tooth whitening. Any apparent brightening is likely due to the mechanical removal of loose surface deposits, which a normal toothbrush achieves more efficiently.

LED and blue-light "accelerators"

In-office light activation was once marketed as a key whitening enhancer. The clinical evidence has consistently failed to support it. A 2026 umbrella review found light systems generally did not improve efficacy and may increase sensitivity.27 The 2014 comprehensive evidence review in the Journal of Evidence-Based Dental Practice found light activation adds no whitening benefit over peroxide alone.28 At-home LED devices using low-energy consumer lights alongside low-concentration gels are almost certainly producing results from the gel, not the light. Save the premium for a higher-quality strip protocol.

Strawberries and baking soda

A popular DIY approach, with no clinical evidence of whitening efficacy. Strawberries contain malic acid, which can briefly lighten surface staining, but the effect is not durable and the acidity could soften enamel with repeated use. Baking soda (sodium bicarbonate) has some mild abrasive and antibacterial properties and is a legitimate low-abrasion ingredient in toothpaste formulas, but rubbing fruit pulp mixed with baking soda on your teeth is not a validated whitening protocol.

09Keeping your results longer

All whitening methods show some color rebound after the active treatment phase. This is normal and documented in every long-term clinical trial. The degree of rebound depends on your diet, oral hygiene habits, and whether you use any maintenance protocol.

A 2013 study tracking color at baseline, post-treatment, and 1, 3, and 6 months found power bleaching showed faster rebound than at-home treatment, with color regression more pronounced at 6 months.29 A 2025 RCT with 24-month follow-up found that combined in-office and at-home protocols maintained color significantly better than in-office alone across the full follow-up period.20

The practical maintenance framework that the evidence supports:

  • Avoid heavy staining beverages for 24 to 48 hours immediately after treatment. Post-bleaching enamel is temporarily more porous. A 2013 study found wine caused greater restaining than coffee, and both effects were most pronounced in the first 24 to 72 hours post-treatment.30
  • Use a whitening toothpaste daily as a maintenance tool to manage surface stain accumulation. It will not deepen your result but it slows re-staining.
  • Schedule touch-up strip sessions every 3 to 6 months rather than repeating full treatment courses. A single week of strips every quarter is enough for most people to maintain results.
  • Professional prophylaxis once a year helps. A 12-month smoker study found effective whitening remained stable at one year after professional cleaning, with only slight darkening without prophylaxis in the intervening period.31

Appearance confidence is a legitimate goal, and a brighter smile is one element of it. If you want to understand how dental aesthetics fit into a broader glow-up framework, the 30-day glow-up challenge covers the full picture, and the looksmaxxing starter kit guide breaks down where to put your resources first.

10Frequently asked questions

With 6% HP whitening strips used twice daily for 30 minutes, measurable color improvement begins within 3 to 5 days and peaks around 2 weeks. Professional in-office bleaching can produce visible results in a single session, though some color rebound occurs in the following weeks. Whitening toothpaste reduces surface staining gradually over 4 to 12 weeks but does not change the underlying tooth color. Timeline depends heavily on the type and depth of staining.

At OTC concentrations (6 to 10% HP), whitening strips used per manufacturer instructions do not cause permanent enamel damage in clinical studies. One in vitro study found transient microhardness reduction at 24 hours that recovered to baseline by day 7 through remineralization. Very high concentrations (35% HP) applied repeatedly in lab settings showed more significant effects. The key factor is total peroxide dose over time, not concentration alone. Overuse, pre-existing enamel erosion, and untreated cavities increase risk.

The evidence does not support charcoal toothpaste as an effective whitening agent. It may remove some surface staining through abrasion, but available studies show no significant whitening efficacy beyond normal toothpaste. More importantly, activated charcoal is often highly abrasive, which over time can wear down enamel rather than clean or whiten it. Charcoal products are also typically fluoride-free, removing a key protection against cavities. The American Dental Association has not approved any charcoal toothpaste to date.

PAP (phthalimidoperoxycaproic acid) whitens through Baeyer-Villiger oxidation rather than the free-radical chemistry of hydrogen peroxide. Lab studies show PAP produces no reduction in enamel microhardness and no surface erosion, while equivalent peroxide concentrations produced measurable hardness loss. A 2026 in vitro study found PAP delivered equivalent lightness improvement to 37.5% HP. Clinical human trials are still limited. PAP is not necessarily better for everyone, but it is a genuinely different chemistry with a cleaner enamel-safety profile in the available data, and sensitivity rates below 3% make it the better choice for sensitive teeth.

Professional in-office whitening produces faster initial results. However, a 2020 systematic review and meta-analysis of 20 RCTs found that while supervised bleaching produced statistically greater spectrophotometer readings, the difference was often undetectable by unaided human eyes. In-office treatment costs significantly more and showed similar or higher sensitivity rates in some trials. The best evidence suggests combining a single in-office session with regular at-home strip maintenance produces the longest-lasting results.

Some color rebound after whitening is normal and documented in every clinical study. The practical approach: avoid red wine, coffee, and tea in the 24 to 48 hours immediately after a whitening session when enamel is most porous; use a whitening toothpaste regularly to maintain surface clarity; and schedule touch-up strip sessions every 3 to 6 months. A 2025 RCT found that combining professional treatment with regular at-home use maintained significantly better color stability at 24 months compared to in-office alone.

Yes, sensitivity is the most common side effect of peroxide-based whitening. A 2009 meta-analysis pooling 7 RCTs found tooth sensitivity in about 20% of users of 6% HP strips over 2 weeks. The mechanism: HP produces free radicals that penetrate enamel and dentin, activating pain pathways in dental pulp cells via reactive oxygen species and calcium channel activation. Sensitivity is typically transient, resolving within 2 to 3 days after stopping. Using desensitizing toothpaste before and during treatment, choosing lower concentrations, and limiting session frequency all reduce risk. PAP-based strips report sensitivity rates below 3%.

No. Peroxide bleaching works best on extrinsic staining (coffee, wine, tobacco) and on mild intrinsic staining within enamel. It is far less effective on intrinsic dentinal stains, including tetracycline discoloration and fluorosis, which are embedded within the dentin and do not respond predictably to OTC products. If standard whitening has not worked after a full treatment course, a dentist can identify the stain type and recommend a suitable approach.

Yes, in most cases. Yellow teeth caused by extrinsic staining (coffee, tea, wine, tobacco) respond well to peroxide-based strips or professional bleaching. Mild intrinsic yellowing within enamel also improves with consistent treatment. Results vary by stain type and depth. If yellowing is caused by dentinal fluorosis, tetracycline, or aging-related dentin exposure, whitening supports the appearance but may not fully reverse discoloration. A dentist can confirm what type of staining you have.

Professional in-office bleaching is the fastest option, producing visible results in a single session of 60 to 90 minutes. At-home, a full day of back-to-back whitening strip sessions is not recommended and does not safely accelerate results. The practical fastest at-home approach: use a well-formulated 6% HP strip twice in one day per product instructions and avoid staining foods for 24 hours. Expect subtle improvement, not a dramatic shift, in one day.

The most evidence-backed at-home methods are: (1) hydrogen peroxide whitening strips (6 to 10% HP) used as directed for 1 to 2 weeks, and (2) PAP-based strips, which deliver similar lightening with lower sensitivity risk. Whitening toothpaste helps maintain surface clarity but does not change underlying color. Oil pulling, lemon juice, and baking soda rinsing are not supported by strong evidence and can damage enamel with repeated use. See a dentist if yellowing persists after a full strip course.

No natural ingredient has strong clinical evidence for genuine tooth whitening. Baking soda has mild abrasive action that can support surface stain removal, and it appears in several ADA-accepted toothpastes, but it does not bleach underlying tooth color. Activated charcoal is often abrasive and typically fluoride-free, making it a net negative for enamel health. For real whitening, peroxide-based or PAP-based strips are the only approaches backed by clinical data, whether or not the formula is marketed as "natural."

Habib A Muflih
Founder of MAXXING

Habib builds evidence-based wellness and skincare content at MAXXING (trymaxxing.com). He reads the primary literature, talks to formulators, and writes what he finds: straight, cited, without inflating what the evidence actually says. For skin questions, see a dermatologist. For dental concerns, see a dentist.

Published June 2026  ·  @trymaxxing

Related reading

References

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MAXXING

Disclaimer: This article is for informational and educational purposes only. It does not constitute dental or medical advice, diagnosis, or treatment. The content uses "supports" language throughout and reflects the available evidence as of June 2026. Whitening results vary by individual, stain type, baseline tooth shade, and product used. For persistent discoloration, tooth sensitivity, gum disease, or any dental health concern, consult a licensed dentist. MAXXING does not sell whitening products. All product mentions are informational only. No brand endorsements are implied.

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