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PAP teeth whitening has become one of the most talked-about alternatives to traditional peroxide whitening, both in dental clinics and in at-home products. At FY Smile, our in-chair whitening uses a PAP-based formula, so we’re often asked how it works, whether it’s as effective as peroxide and whether it’s right for everyone.
This guide explains what PAP is, how it differs from hydrogen peroxide, what the research shows so far, and what to consider before you whiten.
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Table of Contents
What Is PAP Teeth Whitening?
PAP stands for phthalimidoperoxycaproic acid. It is an organic peracid: a compound that releases oxygen to break down the coloured molecules, or chromogens, that make teeth look stained or yellow.
PAP is the active ingredient in PAP+, a whitening formula developed by the Australian company Hismile. At FY Smile, we use Hismile’s Professional PAP+ Whitening formula for in-chair whitening. As well as PAP, the formula contains hydroxyapatite and potassium citrate, which are included to support the enamel and reduce sensitivity.Â
PAP+ is also sold in consumer products, such as strips, pens and powders, but a product you use at home is not the same as a whitening treatment planned and carried out by a dental team. We explain the difference further down.
How PAP Whitens Teeth, and How Peroxide Differs
Teeth can look darker for several reasons. Surface stains build up from food, drinks and tobacco, and teeth naturally look more yellow with age as the enamel thins and more of the yellow dentin underneath shows through.Â
Hydrogen peroxide (and carbamide peroxide, which breaks down into hydrogen peroxide) has been the standard whitening agent for decades. It releases highly reactive oxygen molecules, including free radicals, which penetrate the tooth and break down chromogens. It is well researched and effective, but it can cause temporary tooth sensitivity and gum irritation, particularly at higher strengths.
PAP also oxidises stain molecules, but researchers describe it as doing this without forming free radicals, through a different chemical reaction. This is the main reason PAP is being studied as a potentially gentler alternative.
PAP vs Hydrogen Peroxide at a Glance
| Â | PAP (phthalimidoperoxycaproic acid) | Hydrogen peroxide / carbamide peroxide |
|---|---|---|
| How it works | Oxidises stain molecules without forming free radicals | Releases reactive oxygen, including free radicals, that break down stains |
| Research base | Growing, mostly laboratory studies | Extensive, including clinical studies over many years |
| Whitening effect | Comparable to high-strength peroxide in one independent lab study; less effective than peroxide in another | Well established across a range of strengths |
| Enamel surface | Milder surface changes than 37.5% peroxide in an independent lab study; earlier research linked some PAP formulations to reduced enamel hardness | Higher strengths can alter the enamel surface in laboratory studies |
| Sensitivity | Manufacturer research reports low sensitivity; independent clinical data is still limited | Temporary sensitivity is a known, common side effect |
| Rules in Australia | The concentration limits described below are set for hydrogen and carbamide peroxide | Strengths above 6% hydrogen peroxide (18% carbamide peroxide) are restricted to registered dental practitioners |
Does PAP Teeth Whitening Actually Work? What the Research Says
The short answer is that PAP can whiten teeth, but the evidence is still developing and results depend on the formula and how it’s used. Here’s a summary of the published research.
Research from the manufacturer
The main published study of the PAP+ formula was a laboratory study published in Dentistry Journal in 2021. It found that, unlike the peroxide gels tested, PAP+ did not erode enamel or reduce its surface hardness, and that it improved the shade of stained enamel samples. The authors are employees of Hismile, which makes the product, and the study was carried out on enamel samples in a laboratory rather than in patients.
Independent research
A 2026 laboratory study from the University of Valencia compared PAP with 37.5% hydrogen peroxide and 35% carbamide peroxide on extracted human teeth. PAP improved lightness by a similar amount to 37.5% hydrogen peroxide (7.11 units compared with 7.19), and more than 35% carbamide peroxide (4.43 units). Hydrogen peroxide produced the most noticeable changes to the enamel surface, while PAP produced comparatively mild changes.
A 2023 laboratory study that compared several over-the-counter whitening agents found that hydrogen peroxide was the most effective agent tested. The authors also noted that earlier research had linked some PAP and sodium chlorite formulations to reduced enamel microhardness.
What the evidence doesn’t tell us yet
Most PAP research so far has been done in the laboratory, on extracted teeth or enamel samples. These studies are useful, but they can’t fully show how a treatment performs in a real mouth over months and years. Different products also contain different amounts of PAP and different additives, so results from one formula don’t automatically apply to another.
That’s why we don’t describe PAP whitening as risk-free, or promise a particular number of shades. What we can say is that it is a promising option, and one we assess case by case.
Is PAP Teeth Whitening Safe? Side Effects and Limitations
PAP is designed to be gentler than high-strength peroxide, and the laboratory research above suggests it may cause fewer changes to the enamel surface. As with any cosmetic dental treatment, though, it has limitations and possible side effects:
- Temporary sensitivity or gum irritation may still occur for some people, even though PAP formulas are designed to minimise it.Â
- Results vary. How much whiter your teeth become depends on your starting shade, the cause of the staining and your habits after treatment.
- Crowns, veneers and fillings don’t whiten. Only natural tooth structure changes colour, so existing restorations may look different from your teeth after whitening.
- Some discolouration responds poorly. Deep, internal staining may not respond to whitening, and other options such as composite bonding or porcelain veneers may be more suitable.
- Oral health comes first. Decay, gum problems or worn enamel need to be addressed before any whitening treatment.
Before any whitening at FY Smile, your dentist will examine your teeth and gums, look at any risk factors and areas of sensitivity, and make sure your teeth are healthy enough for treatment.Â
Professional PAP Whitening vs At-Home PAP Products
PAP-based strips, pens and powders are widely available online and in stores. They can be convenient, but there are important differences between using them yourself and having whitening carried out by a dental team:
- A diagnosis first. At-home products can’t tell whether your discolouration is a surface stain, a sign of an underlying problem such as decay, or internal staining that won’t respond to whitening.
- Your restorations are considered. Your dentist can explain how whitening will affect the match between your natural teeth and any existing crowns, veneers or fillings.
- Supervision. A dental team can watch for sensitivity or gum irritation and adjust your treatment.
- The right option for you. If whitening isn’t the best choice, your dentist can talk you through alternatives.
As dental professionals, we always recommend having any whitening treatment carried out, or at least planned, under the supervision of a dental practitioner.
How Australian Rules Treat Peroxide Whitening
In Australia, peroxide-based whitening products are regulated by strength. According to the Australian Dental Association, under the Poisons Standard, products containing up to 6% hydrogen peroxide or 18% carbamide peroxide can be sold directly to consumers if they carry the required safety warnings. Products above those strengths may only be sold, supplied and used by registered dental practitioners as part of their dental practice.
These rules help explain why professional whitening and at-home whitening are different experiences. They also highlight why an examination before whitening matters, whichever whitening agent is used.
Who Is PAP Whitening Suitable For?
PAP whitening may suit you if:
- your teeth have surface staining or have yellowed over time
- your teeth and gums are healthy
It may not be the right choice if you have untreated decay or gum disease, extensive crowns or veneers on your front teeth, or deep internal discolouration. Your dentist will talk you through the options at your consultation.
PAP Teeth Whitening at FY Smile
Our whitening process starts with a consultation. Your dentist will examine your teeth, explain how the treatment works, check whether it’s suitable for you and answer any questions before you decide.
If PAP whitening is right for you, we’ll carry out your treatment in the chair using Hismile’s Professional PAP+ Whitening formula, then give you instructions on caring for your teeth afterwards.Â
Learn more about teeth whitening at FY Smile, or read how long teeth whitening takes.
How to Keep Your Teeth White After Whitening
How long your results last depends largely on your habits. To help your teeth stay brighter for longer:Â
- Limit stain-causing foods and drinks, including coffee, tea, red wine, soft drinks and energy drinks. Sugary and acidic drinks can also affect your enamel; see why we don’t recommend sugary and acidic drinks.
- Avoid tobacco products.
- Brush for two minutes twice a day, and clean between your teeth daily.
- Keep up regular professional cleans. Our hygienist treatments remove surface stains and plaque that build up over time.
Some medications, medical treatments and ageing can also cause discolouration. If you’re taking medication or having medical treatment, talk to your dentist and GP about how it might affect your teeth.
Frequently Asked Questions About PAP Teeth Whitening
Does PAP actually whiten teeth?
Yes, laboratory studies have found that PAP can lighten tooth colour. One independent study found a similar change in lightness to 37.5% hydrogen peroxide, while another found peroxide more effective. Results depend on the formula, how it is used and the type of staining you have.
Is PAP as good as hydrogen peroxide?
The research so far is mixed. Hydrogen peroxide has a much longer track record and a large body of clinical evidence. Some laboratory studies show PAP achieving comparable whitening with fewer changes to the enamel surface, but more research in patients is needed.
What are the side effects of PAP teeth whitening?
PAP formulas are designed to reduce sensitivity and gum irritation, and manufacturer research reports low sensitivity. Some people may still notice temporary sensitivity. Your dentist will check for risk factors before treatment and explain what to expect.
How long does PAP whitening last?
There is no fixed timeframe. How long your results last depends mainly on your diet, whether you smoke, your oral hygiene and how often you have professional cleans.
Is PAP whitening suitable for sensitive teeth?
PAP formulas are designed with sensitivity in mind, and PAP+ includes potassium citrate for this reason. Sensitivity can also be a sign of an underlying problem, so your dentist will examine your teeth before recommending whitening.
Can PAP whiten crowns, veneers or fillings?
No. Whitening only changes the colour of natural teeth. If you have restorations on visible teeth, your dentist can explain how whitening will affect the overall match of your smile.
Is professional PAP+ whitening the same as PAP products bought online?
Not quite. At FY Smile, we use Hismile’s Professional PAP+ Whitening formula as part of an in-chair treatment that begins with a dental examination. At-home products don’t include a professional assessment of your teeth, gums or existing restorations.
