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Teeth whitening
Dr Manasi Bhansali Reviewed by Dr Manasi Bhansali, Dentist

Thinking about professional teeth whitening? Find out how it works, what to expect, potential risks, and other things to consider before deciding.

Most teeth aren’t perfectly white, but they may darken or yellow over time. Tooth discolouration can happen for a lot of reasons, which is why many dentists offer professional teeth whitening as a possible solution.

Teeth whitening may help minimise stains or discolouration, but it’s important to speak to a registered dentist before you undergo any type of tooth bleaching procedure (including over-the-counter methods).

How does teeth whitening work?

There are different forms of teeth whitening, and many of them work by way of a food-grade variation of hydrogen peroxide or carbamide peroxide in the form of a whitening gel. This can create a chemical reaction which lifts surface stains from your teeth, effectively “bleaching them.

In Australia, retail whitening products legally cannot contain more than six per cent hydrogen peroxide and/or 18 per cent carbamide peroxide1, but a dentist may be able to prescribe a higher concentration of peroxide solution. This will depend on what you’re trying to achieve and what the dentist thinks is safe based on your medical and dental circumstances.

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What are the different types of professional teeth whitening?

Two of the most common professional teeth whitening methods are in-chair whitening and take-home whitening. Sometimes, a dentist might recommend combining the two.

In-chair teeth whitening services

A dentist performs this whitening treatment in the clinic (that’s why it’s called “in-chair”) and can typically complete it in a single visit. Before starting this version of whitening, you’ll usually consult with the dentist, who should perform a check-up to ensure this method is suitable for your teeth.

Then, the dentist applies a protective gel to your gums before introducing the whitening solution. They’ll use either a powerful bright light or laser treatment to quickly release oxygen from the solution. This reaction can help lift stains from the surface of your teeth.

Take-home teeth whitening services

Take-home whitening (sometimes called “tray teeth whitening”) involves a special home whitening kit prescribed by your dentist.

In your initial consultation, most dentists will perform a check-up to make sure tray whitening is suitable for your teeth. Then, they’ll typically take an impression of your teeth and use this to create a custom-moulded tray, which looks a little like a thin mouthguard. Your dentist will also prescribe a whitening solution based on your oral health and what you want to achieve.

You'll take the tray and solution home to use for a set number of whitening sessions. Generally, you'll fill the tray with the solution and then fit it over your teeth for a prescribed length of time and repeat this process regularly for a number of weeks specified by your dentist. They should give you full instructions according to the unique whitening product they’ve prescribed, as well as your desired outcome.

Which is better: in-chair whitening or take-home whitening kits?

Neither is “better” than the other, but one may be more suited for your circumstances. For instance, if you’re hoping to whiten your teeth for a big event that’s coming up soon, in-chair whitening may be the right option for you. On the other hand, take-home whitening kits can be gentler for some people and might be preferable if you have more sensitive teeth.

Ultimately, different processes and products will suit different mouths. What’s “better” for you will depend on your oral health, the cause and severity of staining, and any previous dental work.

Who is a suitable candidate for teeth whitening?

Suitability often comes down to the health of your teeth, the cause of staining and any potential health complications.

You may not be a candidate for teeth whitening procedures if you:

  • are pregnant or breastfeeding (whitening chemicals may enter the placenta or breast milk)
  • have sensitive teeth or gums
  • have existing oral health issues; gum disease, tooth decay or cracked teeth should be treated as a priority before undergoing any cosmetic dental procedures
  • have crowns, veneers or fillings, especially if they’re a visible part of your smile.

The cause of staining is also an important consideration ⁠— it may affect the quality of results and you can’t treat some forms of discolouration with teeth whitening.

For example, most whitening procedures aren’t a good solution for stains caused by early exposure to tetracycline. A dentist can help you determine the cause and better understand your options, which is another reason why it’s so important to talk to a professional before undergoing teeth whitening.

Read more about different types of tooth discolouration and potential alternatives to teeth whitening.

Is teeth whitening safe?

Teeth whitening is a non-invasive treatment, meaning there's no need for surgery. But there is still some risk, especially if a registered professional isn’t administering the procedure of if it’s performed incorrectly.

Without a custom-fitted tray or protective gel for your gums, there may be a greater risk of exposure to bleaching agents on your gum tissue. This creates a higher risk of patch whitening or, worse, chemical burns.

Consulting with a registered health professional is usually the best way to lower risks.

How white will my teeth get?

Some teeth may lighten by several shades, only one shade, or not at all. That’s why you might see disclaimers like “individual results may vary” on teeth whitening ads or products.

It's important to have realistic expectations before undergoing treatment. Heavily stained teeth are unlikely to whiten as much as teeth that are already lighter, and you may not see significant results if the discolouration is in the dentine (this is the second layer of your tooth surface, underneath the harder, outer layer called “enamel”).

Ask your dentist to explain what you can expect.

How quickly will I see whitening results?

This depends on a lot of factors but, broadly speaking, in-chair whitening treatments may be the quicker option because they tend to happen in single appointments. Meanwhile, some people need to use take-home trays for 2-3 weeks before seeing visible results.

If you're thinking about whitening your teeth for a specific date, you should discuss this with your dentist to make sure you have enough time to complete the procedure.

How long do teeth whitening results last?

Teeth whitening isn't permanent. For some, it may last between six months and two years. You might see results fade quicker, especially if you smoke or consume a lot of strongly-pigmented foods (like coffee).

Does teeth whitening work with braces or Invisalign™?

It may be possible to undergo teeth whitening treatment if you have braces, but it’s not usually preferable. If you undergo whitening while you’re wearing metal braces, the areas beneath the brackets might look darker or more yellow than those that were fully exposed to the whitening treatment.

It’s usually best to finish your orthodontic treatment before undergoing any teeth whitening, even if you don’t have traditional metal braces. This includes lingual braces (brackets that go on the back of your teeth) and clear aligners like Invisalign™. Changing the position of your teeth can mean that surfaces are exposed in different ways. For example, if you have any crowding in your teeth, only some parts of the teeth will be exposed to the bleaching agent. This could result in a patchy effect once they move into proper alignment.

What should I expect in my teeth whitening appointment?

In your initial consultation, your dentist should discuss your oral health and whitening expectations with you.

Many will perform a basic dental exam to ensure you're a suitable candidate for teeth whitening and, if you are, perform a shade assessment to prescribe the best treatment.

What are the alternatives to teeth whitening?

If teeth whitening isn’t right for you, a dentist can explain any possible alternatives.

Alternatives might include a scale and polish, veneers or crowns. Read more about different types of tooth discolouration, along with possible options for addressing them.

Talk to a dentist

Find a clinic near you to speak with a professional about teeth whitening.

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1 Australian Dental Industry Association (ADIA). For Professionals Teeth whitening product regulation [Online] 2013 [Accessed Mar 2019] Available from: www.adia.org.au

The purpose of this article is to promote better understanding of dental health topics. It’s not meant to replace professional advice or diagnosis. Always talk to a dentist, doctor or other qualified healthcare professional if you have a question about dental or medical conditions.

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