Frequently Asked Questions

The more common questions we are asked are answered below. If you have any other questions then please get in touch.

Frequently Asked Questions

The more common questions we are asked are answered below. If you have any other questions then please get in touch.

Teeth whitening is regulated as a cosmetic product in Europe and must adhere to the EU Cosmetic Regulations. This dictates that the strength of hydrogen peroxide cannot exceed 6% by weight in professional teeth whitening solutions. At 6% strength, professional tooth whitening is very safe when used under the supervision of a dentist. Boutique Whitening is registered with the EU Cosmetics Portal and has been passed by an EU assessor as safe to use. We also have FDA approval pending and our products are approved for sale in Australia.  If you use our products as directed, provided you have no allergies to the ingredients, you should have a safe and comfortable experience with Boutique Whitening.

Teeth whitening is more effective on teeth that are on the yellow and white spectrum. Teeth that are shades of brown and grey are more difficult to whiten and may require a longer treatment, or stronger whitening agents. 

If you have local discoloration that does not respond to whitening to a level that you are happy with, then your dentist may discuss whitening in conjunction with more in depth procedures such as veneers and crowns. 

With all types of teeth whitening products, the results will vary from person to person depending on the original colour of the teeth, the condition of the teeth, the type of staining and compliance with the whitening regime.

Teeth will get stained for a variety of reasons. We categorise staining as intrinsic or extrinsic. In basic terms, extrinsic stains can be removed with professional cleaning, whereas internal stains cannot.

For internal staining we must rely on tooth whitening to enhance the colour of the teeth.

Below are some common examples of intrinsic and extrinsic staining.

Intrinsic Staining:

The success of tooth whitening depends largely on the type of staining present. Intrinsic staining is discolouration that is incorporated into a tooth, either while the tooth is developing, or after it has erupted – this stain cannot be removed by prophylaxis.


Some of the main causes of intrinsic staining are excessive fluoride intake over the period that the tooth develops. The resulting fluorosis manifests itself as either white and chalky enamel, or brown staining. Either way, bleaching can be used in most cases to reduce the contrast of the mottled enamel and improve the appearance.


Another major cause of intrinsic staining is the use of antibiotics, tetracycline and minocycline. These impart a blue-grey banding on the teeth. Severity of staining will differ depending on the type and duration of use. In both cases the staining is similar, however, minocycline can stain teeth both during development and after eruption. Prolonged whitening is usually required in these cases, but more often than not, it must be used in combination with bonding or veneers to get a satisfactory result.


The most common cause of intrinsic staining is trauma which manifests itself in a two-fold process. Firstly, inflammation of the pulp causes hemorrhage into the dentinal tubules to give the tooth a pinkish tinge. The haemoglobin then breaks down to iron sulfide to give a dark black colour. This type of staining responds well to prolonged whitening. Likewise, if a tooth becomes necrotic secondary to trauma, a similar process occurs.  However, treatment in this case must include root canal treatment to remove the necrotic material.


Other common causes of intrinsic staining are hereditary. Imperfections in the formation of either enamel or dentin can cause discoloured teeth. Both amelogenesis and dentinogenesis imperfecta, along with enamel hypoplasia are examples of hereditary causes of intrinsic staining. Diseases like porphyria can also cause discoloured teeth owing to excess porphyrins in the blood during mineralization of the teeth. Affected teeth are usually pinkish brown.


Age also causes intrinsic discolouration of teeth. This is due to changes in the physical composition of the tooth.  Over time, layers of enamel are lost, exposing the darker underlying dentine. Sclerosis and secondary dentine can often take on a darker hue, which also contributes to age related discolouration

Extrinsic Staining:

Extrinsic staining is far more common than intrinsic staining. Extrinsic stains are those that only affect the surface of the teeth and can be removed by prophylaxis. Mostly these arise from the interaction of pigments from food and beverages with the plaque covering the enamel. This can easily be removed by dental prophylaxis and polishing.  When this type of staining penetrates the microscopic cracks and fissures of the teeth, they cannot be removed by tooth-brushing or dental prophylaxis. In these instances, whitening is required. The most common causes of extrinsic staining are coffee, tea, red wine and smoking.

Boutique Whitening by Day is a 6% hydrogen peroxide gel. Hydrogen peroxide is inherently unstable and will break down immediately when you place in the whitening trays. The majority of the peroxide will be spent within the first 20 minutes of wear, but to get the full effect of the gel, we recommend at least 1 to 1.5 hours of wear time.

Boutique by Night has several different protocols all designed for a minimum of 4 hours’ wear time, but preferably to be kept in overnight, so you can whiten as you sleep.

We have a 10% carbamide peroxide gel, or a 16% carbamide peroxide gel.

These are the equivalent of 3.5% hydrogen peroxide and 5.7% hydrogen peroxide, respectively. Both gels will give you a fantastic white smile.  It’s just the 16% will get you there a little faster. If you suffer from sensitivity, the 10% is the way to go.

Boutique also manufacture a 4.25% Hybrid Pro gel. This is a blend of 4.25% hydrogen peroxide and 4.25% carbamide peroxide. This gel is designed to be worn overnight and delivers a gentle nudge with the hydrogen to get things started, whilst the carbamide slowly ramps up, to deliver a powerful dose of whitening, but very gently, as you sleep.

A man named Louis Jacques Thenard discovered it in 1818. Hydrogen peroxide is a potent oxidizing agent. The whitening action is a result of oxygen free radicals that oxidize larger pigment molecules into smaller, less visible molecules.

By the European Directive dental professionals are only permitted to sell products that contain a maximum of 6% hydrogen peroxide. Over-the-counter products that do not require the supervision of a dental professional may contain only 0.01% hydrogen peroxide. These products are ineffective in whitening the teeth as the concentration of peroxide is too low.

Carbamide peroxide is hydrogen peroxide compounded with urea. Urea helps stabilise the formula giving carbamide peroxide a more predictable and longer shelf life than hydrogen peroxide alone.

By the European Directive, dental professionals can prescribe up to 16% carbamide peroxide. In the presence of water, carbamide peroxide degrades into urea and hydrogen peroxide. Any given volume of carbamide peroxide will yield 35% volume of hydrogen peroxide when it breaks down.

A notable difference between hydrogen peroxide and carbamide peroxide is the rate of breakdown, and therefore, the rate of release of oxygen ions. Carbamide peroxide is a more stable molecule and breaks down more slowly than hydrogen peroxide. Carbamide releases about 50% of its peroxide in the first 2 to 4 hours, then the remainder over the next 2 to 6 hours.

Hydrogen peroxide breaks down almost immediately, releasing its peroxides entirely within the first hour. It is thought that due to this relatively concentrated bombardment of peroxides on the pulp, hydrogen peroxide produces more sensitivity than carbamide peroxide of a comparable concentration.

A typical procedure would require one visit for a comprehensive dental examination. Legally, this must be done prior to teeth whitening. Photographs and impressions can be taken during this visit.

You would then return in two weeks to have your new whitening trays fitted to begin your teeth whitening.

You would whiten for between 3 and 4 weeks.

You would then return for final assessment and photographs to see how effective your teeth whitening treatment has been.

Teeth whitening is not permanent. The duration between top up teeth whitening depends mainly on lifestyle choices. People who smoke or consume food and beverages that stain teeth, such as red wine, coffee and curries, will find that they need teeth whitening at more regular intervals. If your lifestyle involves one or more of these factors then you may require top-ups every 3 to 4 months. Most people will require a top-up on their teeth whitening at 6 monthly or yearly intervals.

Thanks to the wealth of research that exists around teeth whitening products, people no longer have to walk around with stained or yellow teeth.  A visit to the dentist, and you can be smiling like a movie star after a short course of teeth whitening which can be done in the comfort of your own home. 

The dentist can help get your teeth beautiful and white.  However, there are some habits that you can adopt to ensure your teeth stay whiter for longer. Here are three top tips to help you keep your beautiful white smile.

Good oral hygiene is essential for anyone wanting to maintain a brighter, whiter smile. Use one of the market-leading electric toothbrushes (we particularly like the Oral-B ones) and a good quality fluoridated toothpaste, and brush twice a day. Floss at least once a day. Plaque build-up on the teeth looks unsightly and can lead to staining. Daily cleaning will remove surface staining and plaque, giving the teeth a much nicer appearance to help maintain your teeth whitening.

Keeping your teeth white requires a little care and attention in your dietary and social habits. While practicing good oral hygiene is clearly important, watching what you eat or drink is just as critical. Red wine, sports drinks, tea and coffee, soft drinks and curries  are just some of the foods that can cause staining of your teeth and diminish the effects of teeth whitening.

Teeth whitening will improve the colour of your teeth but they will eventually begin to fade back towards a darker shade. It is not enough to get whitened once – you must commit to a programme of top-up whitening in order to keep them that way. Your dentist will be able to advise you on the best maintenance programme for your smile.

Lifestyle factors, such as smoking and dietary choices, will affect how often you require top-up teeth whitening treatments.

The main side-effect of teeth whitening is sensitivity. Up to 70% of people who have teeth whitening will experience some form of sensitivity, from mild discomfort to great discomfort.  Some people may also feel some slight irritation of the gums or lips. Both of these effects are temporary and will resolve, given a little time, after stopping or finishing your treatment.

Tooth whitening is a very safe procedure when performed correctly. However, there are some potential side effects that you must inform the patient about prior to the procedure.  It is also important to have the knowledge to circumvent these issues to help patients achieve a fantastic result.

Protocol for Extreme Sensitivity:

The most common side effect of any whitening procedure is sensitivity. This problem affects, to varying degrees, up to 75% of whitening patients. Sensitivity is a major issue if the patient cannot continue with the whitening

The protocol for treating patients with extreme sensitivity is as follows:

Gingival Irritation:

Another potential side effect of the whitening process is  gingival irritation. This occurs when the whitening gel has  prolonged contact with the gingival tissue. This can be avoided by educating the patient that they need only fill the dosing dots on the tray and no more.  This will avoid an excess of gel and the subsequent gingival irritation. If they do have any excess of gel, then this should be removed with a clean tissue or soft toothbrush.

The best way to limit most problems is to ensure that the trays are well made by a laboratory. The quality and precision required is impossible to recreate in surgery made trays.  Isolation of the bleaching product from the rest of the mouth will successfully limit most problems.

Likewise, patient education on how to properly fill the trays will also help.

Disappointing Results:

This is a classic example of making sure that you under promise, and over deliver, in your initial talks with the patient, and the treatment that follows. Tooth whitening is not an exact science, and 1 pack of whitening does not always equal the perfect result for your patient. It may take more. This should always be made clear from the outset.

We know from the Van Haywood studies that hydrogen peroxide will whiten the teeth in almost all cases. If the teeth do not whiten, the answer is to extend the treatment time. This approach will rarely fail.

Bruxists and Tooth Whitening:

If you are attempting overnight whitening on a patient with nocturnal bruxism, the results will likely be poor.  As the patient clenches and grinds, the flexing of the trays will cause saliva ingress and washout of the whitening gel. In these patients, the best option is to use Boutique by Day gel.

The effect of whitening gel on enamel, dentine and pulp:

Tooth whitening is one of the most researched cosmetic procedures in the world and has a wealth of evidence to support the effectiveness and safety of the take home technique, if correct protocols are observed. There are many studies that exist which demonstrate the effects of peroxide on the various layers of the human tooth.


Enamel is not significantly affected by the use of peroxide based products. A study by Leonard, et al, in 2001 assessed the effect of 10% carbamide peroxide on the surface morphology of enamel after 2 weeks, and again after 6 months, using electron microscopy at 2000 times magnification. There was no significant effect on the surface of enamel immediately after whitening and it did not worsen over time.


Dentine is affected more by the whitening process than enamel tissue. Spyrides GM, et al, study from 2000 showed that dentine bond strength decreased by as much as 76% post whitening. Further research from Na-Young Jeong, et al, in 2006 showed that 2 weeks was sufficient to allow the dentine to recover and bond strengths returned to near the same as pre-whitening levels. Always schedule any restorative work at least 2 weeks after the patient has finished whitening. If there is any immediate bonding required,  soaking the dentine in a 70% ethanol solution or 2 minutes can restore bond strengths to near pre-whitening levels.


Owing to the sensitivity associated with tooth whitening, it is often wrongly assumed that whitening causes pulpal damage.  JO Fugaro, et al, did a study in 2004 on the reaction of pulpal tissue to two weeks use of 10% carbamide peroxide. The findings from this study demonstrated that 10% carbamide peroxide can cause mild, localized pulp reactions, however, these did not affect the overall health of the pulp tissue and were reversible within two weeks post-treatment. Therefore, two weeks of treatment with 10% carbamide peroxide is considered safe for the pulp.

Another study by Cohen showed that hydrogen peroxide up to 35% concentration was harmless to the pulp. It is a safe assumption that no long term harm will come tothe pulp from the concentrations of whitening solution that are used in home whitening

There are numerous studies to show that teeth whitening gels do not in any way damage dental restorations.   Restorations such as tooth-coloured fillings, crowns, bonding, veneers and bridges will not whiten. However, be aware that any pre-existing dental work may need to be replaced to match the new colour of the teeth.

Teeth whitening will only work to lighten the natural teeth. It will not lighten existing dental work at all. Be aware that you may need to change any crowns, veneers or fillings after you have teeth whitening. You will need to discuss this with your dentist prior to having the treatment, to ensure you are aware of the costs and appointments involved.

Absolutely not! There are several reasons as to why this is a dangerous idea. Teeth whitening is an act of dentistry and can only be done by a dentist, or under the supervision of a dentist, by appropriately qualified professionals. You must have a comprehensive dental examination prior to teeth whitening and this cannot be done by hairdressers and beauticians.


The peroxides used by dentists are strictly monitored and used in a way that we know will give maximum benefit with no adverse effects.


By letting unqualified people with no knowledge of chemistry and dentistry work in your mouth, you are risking burns, scarring and permanent disfigurement. Please follow this link to see the stories below of issues that have occurred when people let hairdressers and beauticians provide teeth whitening.

Read the horror stories

Teeth which seem at an acceptable shade, which is subjective for clinician and patient.

Presence of composite restorations, mixed with natural tooth structure, which will not 

lighten with treatment. They may need replacing post whitening.

Porcelain restorations such as crowns and veneers will not lighten, and may 

require replacement after whitening treatment. 

Pregnant or lactating women.

Patients who are unable to be compliant.

Patients with unrealistic expectations.

Patients with exposed cementum and exposed root surfaces. 

Cementum does not lighten.

The Regulations and EU Directive specifically state the product must NOT be used on patients aged under 18. 

This can create an ethical dilemma for dentists who wish to act in the best interests of their patients, but where the treatment is prohibited by the Regulations by virtue of the patient’s age.

In this scenario, it is an individual clinical decision whether to breach the Regulations and provide the treatment in the best interests of the child. 

In order to do this, the dentist must follow the following protocol:

  • Have a detailed discussion with the patient/parents, as part of the consent process.
  • Ensure that patient/parents are fully informed as to the risks and benefits of both whitening procedures, and the more invasive alternatives.
  • Discuss whether it is appropriate to delay treatment until the patient is 18 years of age.
  • Contact an indemnity provider for advice.

If there is a clear case of disease whereby the child can be helped by teeth whitening, the case is more compelling, but the dentist must still follow the steps laid out above to stay on the right side of the law.

Supervised Home Whitening:

Dentist-supervised home-whitening is the safest, most popular, and most well-researched whitening procedure.  As with all dental procedures, the first step is a thorough assessment and diagnosis, coupled with good quality photographs showing the closest matching shade tab (always ensure you can see the label of the shade tab).

The trays you wear to do home supervised teeth whitening are very important to ensure a successful outcome.  The trays from Boutique Whitening are manufactured in a very specific way.

Laboratory made trays versus in-house trays:

This technique requires the manufacture of custom fabricated trays by a laboratory skilled in the use of thermoplastic materials – they should NEVER be manufactured by the dentist in house. The time taken to manufacture trays in-house negates any cost saving, and the lack of quality will adversely affect the outcome of the treatment.The ideal work-flow to manufacture the trays is outlined below. This would be difficult to recreate when manufacturing the trays in-house, hence our recommendation to always have laboratory made trays.

Trays should ideally be made with a 1.5mm single-skin, semi-rigid material. Vacuum and pressure forming together will ensure a tray that is a close fit to the model. Vacuum forming alone usually results in a poor fitting tray. The gingival margins should be carved prior to forming. This creates a marginal seal to prevent ingress of saliva, and wash-out of the gel.There are two schools of thought as to how the margins of the tray should be finished – scalloped or straight. Boutique trays come with a straight margin. This requires less finishing which results in a closer fitting, more stable tray. If a whitening tray has reservoirs then a scalloped margin is better to ensure excess gel can be removed easily.The literature shows that reservoirs are not required. Boutique trays are manufactured with no reservoir, however, they do have a ‘dosing dot, basically a small dimple on the labial surface of each tooth. The patient simply has to fill the dot to ensure the correct volume of gel is dispensed. This means less problems with sensitivity due to over filled trays and gel touching the ginginvae. The kits also last longer, which in turn gives better results

There is a perception amongst the public that in-surgery whitening using lamps or lights (it is never a laser!) is a superior way to whiten teeth.

This raises some controversy and polarises opinion. The theory is that the light ‘activates’ the teeth whitening gel in some way, increasing the rate of free radical release.

There are numerous studies showing the lights to be effective….however, these are usually done by the companies that manufacture the lights themselves, so you draw your own opinion as to how credible these are. These should be approached with an open mind!

So, although there is questionable evidence to prove the effectiveness of lamps, if you wish to use this method and you enjoy the experience then the choice is up to you.

There is, however, an overwhelming body of evidence to show that dentist supervised home whitening is very effective, and produces consistently superior results. Boutique Whitening is designed using the most up to date scientific data available, so we do NOT use in-surgery whitening, because the evidence does not support this as a good option for teeth whitening.

Are you ready for a whiter, brighter smile?

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