If you’re one of the 48% of the UK population who plan to undergo teeth whitening in the coming year, you probably have a good understanding of the choices available. But have you ever stopped to think about how teeth are whitened and what actually happens?
In this post, we’ll take a fascinating glimpse inside the teeth-whitening process and how it works to turn a dull-looking smile into something truly special. But before we start, we need to address the confusion surrounding teeth whitening products.
Bringing clarity to teeth whitening products
Many products on the market promise a whiter, brighter smile. Options include a multitude of over-the-counter (OTC) products like whitening toothpastes, gels, pens and whitening systems; or whitening treatments either supplied by or carried out by, your dentist.
Most contain a bleaching agent like hydrogen or carbamide peroxide, while others, like whitening toothpaste, contain abrasives such as silica or pyrophosphates.
Essentially abrasives are designed to only remove surface staining using a polishing (brushing) action. Whereas products containing bleaching agents are designed to penetrate the enamel and can also shift ingrained (intrinsic) staining.
So far, so good, but this is where it gets a little tricky…
Not all whitening products are created equal.
From a legal perspective, in the EU especially, OTC whitening products – those sold directly to the public, are only permitted to contain a small amount of bleaching agent, just 0.1%. In reality, this concentration is far too low to have any noticeable effect on teeth.
In Australia and the US, peroxide levels are permitted to be greater, typically up to 6%.
However, in most countries, whitening products supplied by a dental professional are legally allowed to contain higher concentrations of bleaching agents.
For example, take-home kits supplied by UK dentists are legally allowed to contain up to 6% hydrogen peroxide. In the US, this figure rises to 10% whereas supervised in-office whitening treatment can contain far higher levels of hydrogen peroxide up to 30%-35% in most countries.
So, what can consumers expect?
Essentially, they can expect a considerable difference in results depending on treatment type. As a general rule of thumb, consumers should expect OTC whitening products to be less effective than dentist-supervised or dentist-led products, or at the very least, take longer to achieve results.
Alternatively, dentist-led treatments, particularly those like laser teeth whitening, can show significant results in as little as one hour.
So now, that we’ve brought some form of clarity to teeth-whitening products, let’s talk about what happens when you whiten teeth. In other words, how do bleaching agents work?
Teeth whitening – How it works
Essentially, teeth stain or darken due to factors like lifestyle, diet or age. The only substance proven to whiten teeth is active oxygen found in hydrogen peroxide. It’s important to note that bleaching agents like hydrogen peroxide are considered safe to use on teeth, given the right environment and used in the right way.
When hydrogen peroxide (the bleaching agent found in teeth whitening products) is applied to the surface of the tooth, it penetrates the porous enamel and the active oxygen compounds contained within attach themselves to the intrinsic molecules that cause surface and ingrained staining.
As they do so, the active oxygen converts the darker-coloured molecules into simpler and far lighter structures giving the appearance of whiter, brighter teeth.
In some cases, blue UV (laser) lighting is used to activate the process. When the light is applied to the gel it causes a chemical reaction, forcing the compounds in the gel to break down and release the active oxygen molecules that much faster.
The technique of applying UV light to speed up the activation process is normally carried out during an in-office procedure but UV technology is also cleverly built into some over-the-counter products such as whitening kits.
One important thing to remember is that it can take time for the oxygen compounds to convert the darker-coloured stain molecules to a lighter shade; so, while a difference can be seen after one laser whitening session, most people notice the shade getting progressively lighter up to 7 days after treatment.
So what can you realistically expect from teeth whitening treatment?
Well, it depends on several factors, including:
- The type of treatment – Chairside vs at-home, vs OTC
- The current condition of your teeth – The current level of whiteness; and
- Lifestyle and dietary habits after treatment
Let’s take each one of those points in turn…
Type of treatment
We know that hydrogen peroxide, or rather, the active oxygen contained within, whitens teeth. Therefore, the greater the hydrogen peroxide level, the more effective whitening will be. We’ve also said that many OTC treatments, particularly those sold within the EU, contain very little or no bleaching agent whereas chairside treatments contain the most, with dentist-supervised take-home kits sitting somewhere in the middle.
With this in mind, we can deduce that the type of treatment chosen will often determine how effective the results are.
In other words, if you require a surefire and quick way to whiten teeth, chairside teeth whitening takes some beating.
Current levels of whiteness
You may be surprised to know that not everybody’s teeth start at the same level of whiteness. Children’s teeth, for example, naturally vary in shade and can be influenced by factors like genetics. Other factors like diet, lifestyle and oral habits also come into play as we grow into adulthood.
For example, if a person naturally has lighter-coloured teeth and requests to go 7 or 8 shades lighter, it may result in an exceptionally white appearance (known as an A1 shade) which can look unnatural.
Alternatively, if a person with initially darker teeth aims for 7 or 8 shades lighter they will be left with a shade lower down the whiteness scale – typically an A2 or A3 shade.
While A2 is considered by most dentists to be a more subtle and natural look, the latter person is unlikely to ever achieve the A1 shade of the previous person. Why? Because both parties were at different starting points before commencing treatment. In other words, it’s an uneven playing field!
The final point has to do with lifestyle and diet and it’s this…
Post-treatment - lifestyle and food choices
One key point to mention is that unless you live on a diet of lettuce and water, any treatment that whitens teeth isn’t permanent. Stain-inducing foods and beverages, lifestyle habits like smoking plus the natural process of ageing, all play their part in eventually dulling a smile.
That said, those people who regularly drink coffee, and red wine or who smoke will need top-up whitening treatments far more frequently than someone who sticks to a ‘white diet’ such as yoghurt, pasta, fish, chicken and bananas.
Provided you’re more careful about what you eat, you should be able to keep a whiter brighter smile for longer than someone who isn’t.
So, there you have it…
What you should know about teeth whitening products and treatments, what happens when you whiten teeth and what you can expect during and after treatment.
Remember, if carried out in the right way, cosmetic teeth whitening is a safe and effective way of achieving a brighter, whiter smile and a huge dose of confidence to boot! Interested? Book a consultation with your local dentist today!