What is the safest way to whiten your teeth? Why do you need to beware of the over-the-counter teeth whitening kits? To get an expert opinion, we sat down with the dental expert and lecturer of the Curaden Academy, Dr. Mia Girotto.
1. Why do teeth stop being white in the first place? It’s bone, isn’t it? It has to stay white?
First things first – teeth are not bone. They are comprised of mineralised tissue; they are similar to bone, but not really bone. The main tissues are dentine and enamel, and the colour of your teeth is a mix of the shades of these two main components of the hard part of the tooth.
Dentine makes up much of your tooth and has a brownish-yellow hue. Enamel is covering the dentine, and it is one of the hardest materials found in nature. It has a whiter, and slightly blueish hue, but it’s also semi-translucent and quite thin.
So the colour of your teeth is ultimately down to three things: the colour of your dentine and both how thick, and how stained, your enamel is.
Children have whiter teeth because their enamel is thick. As we grow older, the enamel wears off, and more of the dentine shows through.
Over the years, the enamel acquires tiny cracks, scratches and openings, which are all ideal surfaces for food stains. This is how the discolouration usually starts. It’s completely normal.
Accumulated over the years, these tiny traces from foods can make up the darker tint that is characteristic of grown-up teeth.
The colour of your teeth is ultimately down to three things: the colour of your dentine and both how thick, and how stained, your enamel is.
Basically, everything you eat that has colour can leave tiny traces on your teeth, including vegetables, fruit and berries. Some substances are especially staining, for example wine, coffee and tobacco.
You can see it in smokers: tar is literally embedded in the pores of their enamel. Vapers are risking just as much; nicotine is colourless when liquid, but becomes brownish when mixed with oxygen in the air.
Bottom line: teeth get darker, because we use them.
2. Can I avoid natural darkening of teeth?
Sure, to some extent.
If you want to keep your teeth whiter for longer, follow the basic oral hygiene routines: brush diligently, focus on your technique and brush every hard surface in your mouth – gently, front and back, with a soft, high-density toothbrush. You can also use an electric toothbrush.
Over the years, the enamel acquires tiny cracks, scratches and openings, which are all ideal surfaces for food stains.
The main point is to not skip any of the hard surfaces in the mouth. You’ll have to brush all the surfaces of all your teeth, interdentally as well, including any prosthetics you may have as a replacement for lost teeth.
Another crucial thing – avoid colour-intensive substances, especially those ‘unhealthy’ ones such as tobacco. Too many sugary drinks are also a problem because they can contain acids (commonly citric and phosphoric acid).
Acids offset the chemical balance of the enamel and make it susceptible to formation of ‘pores’, which can then become discoloured. Regular exposure to acids also makes the enamel more susceptible to decay.
But even when you follow these rules, your enamel will still deteriorate over time. You can’t just stop using your teeth to avoid all damage. Our teeth wear down and become less white, that’s just nature’s way.
3. What does professional whitening do?
Your dentist can offer you a whitening service. It’s typically a mix of two procedures: bleaching and polishing your enamel.
With bleaching, your dentist will apply a special gel that contains a bleaching agent. For example, many gels use hydrogen peroxide – the same agent that is used to bleach hair and is used in laundry detergents.
The bleaching agent does what it says on the box – it breaks up the organic components that make up the stains.
It is essential to do bleaching under supervision, in licensed professional practices. In some cases, a professional might even advise you against this procedure.
When it’s too aggressive or used for prolonged periods of time, it can break up some of the enamel too, which is why this procedure must be done strictly under supervision – in licensed professional offices, with careful dosage and timing, along with the protective measures that need to be applied both during and after the procedure.
After the procedure, you’ll get extensive recommendations on how to take care of your teeth, and there will be a supervision protocol. When done unsupervised, some bleaching products can do a lot of damage, so bleaching has to be done by a dental professional.
With polishing, your dentist smooths out the surface of the enamel (its top layer) in an attempt to reduce the grooves and cracks, which in turn is expected to reduce the discolouration and the accumulation of the bacteria, as well.
Your enamel will feel super smooth after the procedure, but in time it will acquire dents and scratches again, just like normal enamel would.
4. How does bleaching and polishing affect the enamel?
In short and in general, bleaching and polishing makes the enamel thinner, and thus weaker – especially if using some of the more aggressive materials, and without proper protection.
This could sometimes cause side-effects such as increased sensitivity to temperatures and pressure, and weaker protection of the dentine – especially for people with thinner enamel.
I can’t stress this enough – it is essential to do this procedure under supervision, in licensed professional practices.
Remember: only a professional can evaluate your teeth correctly, and decide on the best possible procedure as well as the materials which can be used.
Dental professionals know how to determine the best possible procedures and the best materials to use, so as to lessen these unwanted possible side-effects. In some cases, a professional might even advise you against this procedure.
The ‘sad’ part is: after all these procedures, we still need to use our teeth. We have to chew and grind, and unless one will change their eating habits completely, their teeth will inevitably become discoloured once again.
So a regular supervision regimen is required. It is a very good idea to visit your dentist more often to monitor your teeth after whitening.
5. Why don’t we just restore the enamel?
Interesting fact: although almost anything else can be regenerated, our bodies can’t naturally regenerate enamel. Once enamel has eroded, it’s gone.
The best way to keep enamel strong is by maintaining proper oral hygiene.
It’s vital to brush with a proper technique – with very gentle and light pressure, and of utmost importance: with the correct type of the bristles on your toothbrush. The toothbrush should be very gentle, but very efficient at the same time.
When you brush regularly, you disrupt the bacterial colonies that settle on your teeth, so they don’t get the chance to influence the surface of the tooth with their toxic waste. You also keep the gums healthier, which contributes to the overall health of your teeth.
Also, it is recommended to use toothpaste that could potentially help in the remineralisation of the enamel, but it has to be non-abrasive, which is even more important.
Maybe one day chemists will invent artificial enamel, and we’ll learn to restore it to its original state, but for now – it’s prevention over repair.
In short: we have to take care of our enamel while we still have it. Even though some therapies such as polishing aren’t necessarily bad, we shouldn’t do it too often. In any case, always consult your dentist before putting more strain on your teeth.
6. What about at-home whitening?
In some countries, pharmacies sell over-the-counter teeth whitening kits, and you can even buy them online. These are essentially tooth-bleaching gels of different intensities.
The main risk with such whitening kits is possible overuse. To get faster results, people tend to use the gel for longer or more often than it says in the manual.
Worse still, some people start a ‘whitening regime’, which exposes their teeth to bleach for longer, and on a regular basis. This is a terrible idea – in some cases it can do permanent damage and make the enamel extra-thin and sensitive.
A safer way to whiten your teeth at home is by using whitening toothpastes, which doesn’t have fast results, but it is more gentle to your enamel.
A good and safe whitening toothpaste should contain a low concentration of the bleaching agent, so that it can be used for prolonged periods to safely remove stains from enamel. An example of such a mild agent is glucose oxidase, an enzyme found in honey which gives it the antibacterial properties. It turns sugar into oxygen which eliminates staining elements.