Short answer: Home teeth whitening methods often recommended online, such as lemon, baking soda and activated charcoal, can wear down tooth enamel or soften it with acid and can cause sensitivity. In many cases it has not even been shown that these methods actually whiten the teeth. "At-home whitening" in the professional sense means a method carried out in a controlled way using custom trays that the dentist prepares after an examination; the two are very different from each other.
Why do teeth change colour?
Before assessing whitening methods, you need to know the cause of the discolouration. In general, two types of staining are described:
- Surface (extrinsic) staining: Stains left on the tooth surface by tea, coffee, cola, wine and smoking. In most cases these can be reduced noticeably with a professional dental cleaning and polishing.
- Intrinsic staining: Colour change in the inner structure of the tooth caused by things such as enamel thinning with age, certain medicines, knocks to the tooth or root canal treatment. This type of staining does not improve with surface cleaning.
We cover the effect of smoking on tooth colour in detail in our article how smoking affects teeth.
Why are methods tried at home risky?
Lemon and other acidic fruit
Lemon juice is acidic. When rubbed on the tooth surface it temporarily softens the enamel; brushing at this time can speed up enamel loss. Once enamel has worn away, it does not regenerate. Because thinning enamel can make the more yellow tissue underneath more visible, teeth may actually look darker over time.
Baking soda
Because baking soda wipes away surface stains mechanically, it can give the impression that the teeth look cleaner in the short term. However, when used with frequent, hard brushing, it can wear down the enamel and the sensitive surfaces at the gum line. Mixing it with lemon is even riskier, as it combines the effects of acid and abrasion.
Activated charcoal
Activated charcoal powders and toothpastes are generally abrasive. They may remove some surface stains, but they have no effect on intrinsic staining. Charcoal particles can settle at the edges of fillings, along the gum line and between the teeth, leaving a dark appearance.
Other "natural" suggestions
Methods using strawberries, apple cider vinegar, salt or various oils are also widely shared online. Some of these contain acid and some involve abrasion; there is no reliable evidence that they whiten the teeth.
Unsupervised whitening products
Whitening gels, strips or products of unknown content used without a dentist's assessment can lead to burning of the gums, severe sensitivity and uneven colour results. If there is decay or a crack in the mouth, these products can make the problem worse. So rather than choosing a product online or from a cosmetics aisle and using it on your own, we recommend consulting a dentist first.
Reducing discolouration with daily habits
Some simple habits that help protect the colour of your teeth can also reduce the need to turn to risky home methods. The main ones are brushing twice a day with a soft brush and gentle movements, keeping up cleaning between the teeth, rinsing your mouth with water after coloured drinks such as tea and coffee, and giving up smoking. Waiting a while after acidic drinks instead of brushing straight away can also help protect the enamel. Regular dental check-ups and professional cleaning when needed limit the build-up of surface stains.
What is dentist-supervised at-home whitening?
In professional at-home whitening, the process starts with an examination. The dentist assesses conditions such as decay, gum disease, exposed root surfaces and old fillings. If it is found to be suitable:
- Impressions of your teeth are taken and thin, clear trays are made specially for you.
- The whitening gel chosen by the dentist and how long and how often to use it are explained to you.
- The whitening is done at home, but the process is followed up with check-up appointments.
- If sensitivity occurs, the dentist can adjust how often you use it or recommend a break.
You can read about the differences between in-office and at-home whitening in our article teeth whitening methods, and find general information on our teeth whitening page.
What to know before whitening
- Fillings and crowns do not whiten: If there are fillings, veneers or crowns on the front teeth, a colour difference can appear after whitening; this needs to be planned for.
- Sensitivity can occur: Temporary sensitivity is common during and after whitening. For the causes of sensitivity, see our article why teeth become sensitive.
- It may not be suitable for everyone: Whitening is usually postponed during pregnancy and breastfeeding, in cases of significant gum disease or untreated decay, and in young people whose teeth are still developing.
- Results vary from person to person: The shade achieved and how long it lasts depend on the structure of the tooth, the type of staining and your habits.
Orthodontic treatment and whitening
For people who are considering or already having treatment with braces or clear aligners, the timing of whitening should be planned separately. In most cases whitening is considered after orthodontic treatment has been completed. We explain this in our article teeth whitening after braces and on our orthodontics and whitening page.
Frequently asked questions
Do whitening toothpastes work?
These toothpastes are mostly aimed at reducing surface stains and do not noticeably change the tooth's own colour. As some can be abrasive, it is best to consult your dentist before using them on sensitive teeth.
Does brushing with baking soda damage your teeth?
When used with frequent, hard brushing, it can wear down the enamel and the sensitive surfaces at the gum line. The risk is even greater when it is mixed with lemon.
Does whitening thin the enamel?
With whitening carried out under a dentist's supervision using a suitable method, the aim is to reduce the risk of harming the enamel. Home methods that involve acid or abrasives, however, can affect the enamel directly.
What should you do if you get sensitivity after whitening at home?
Take a break and consult your dentist. Once the cause of the sensitivity has been assessed, how often you use it can be adjusted or a different approach may be suggested.
How can you find out what suits you?
The information here is general; the right option for you is determined through an examination and the dentist's assessment. For appointments and directions, see our contact page.
