Fluoride does not whiten teeth because it can’t mechanically remove stains nor chemically oxidize them. Despite fluoride not being able to whiten your teeth, it does interact with and affect them in a different kind of way.
We’re going to explain everything there is to know about how teeth whitens and why sodium fluoride lacks the ability to do so. Nonetheless, it doesn’t make it a bad product because it does have other beneficial uses. It’s just that it doesn’t whiten teeth but you should still use it because it is good for them!
Teeth whitening removes extrinsic and intrinsic stains
Teeth become yellow as a result of accumulating extrinsic and intrinsic stains. Therefore in order to reverse the process and make yellow teeth turn white again, you must get rid of the stains. That is the entire basis for what teeth whitening is.
According to the American Dental Association (ADA), extrinsic stains are removed mechanically while intrinsic ones are removed chemically via a whitening agent. The mechanical removal of stains is a physical process like brushing your teeth. The chemical removal occurs via oxidation by utilizing hydrogen peroxide or a derivative of it.
Since fluoride lacks both of those properties, it doesn’t seem likely that it can whiten your teeth. If you brushed with a fluoridated non-whitening toothpaste, your teeth will stay yellow even if you brushed everyday.
Fluoride cannot mechanically remove extrinsic stains
Fluoride does not remove extrinsic stains because the process involves mechanically brushing them off. In other words, you have to physically brush or scrub the surfaces of your teeth in order to get the discoloration off.
During fluoride treatment, your dentist will usually gently paint the sodium fluoride onto the surfaces of your teeth. This process involves zero vigor because everything is done softly and gently.
Since the treatment does not involve any mechanical removal, we can conclude that fluoride does not whiten your teeth because it does not remove extrinsic stains.
How whitening toothpastes with fluoride whiten teeth
You’re probably thinking that your whitening toothpaste has fluoride in it but why does that whiten your teeth but sodium fluoride alone does not? That is a great question and we’re glad you asked!
You are correct in that the vast majority of whitening toothpastes do indeed contain fluoride within it. However according to a study in the Journal of Dentistry, what permits it to whiten teeth is the abrasive ingredient in it. Different toothpastes will utilize different abrasives in order to accomplish this.
|Toothpaste||Whitening Abrasive||Relative Dentin Abrasivity (RDA)|
|Colgate Total||Hydrated silicon dioxide||44|
|Oral B, Colgate whitening, Sensodyne||Hydrated silica||65|
|Tom’s||Calcium carbonate, Sodium bicarbonate, hydrated silica||49|
|Clinomyn||Calcium cabonate, Silicon dioxide, Aluminium silicate||124|
The chart above was from a study in Acta Odontologica Scandinavica, which measured the abrasive qualities in toothpastes. Consequently, it is due to the abrasives within toothpastes which give it the ability to mechanically remove extrinsic stains. It appears that different brands will use different abrasives in their product but their purpose are all the same which is to remove stains and whiten teeth.
We added a few additional toothpastes to the chart since they are common in the United States. It is interesting to note that some toothpastes like Tom’s utilize a combination of different abrasives.
With that being said, fluoride is not an abrasive and is therefore not used for whitening your teeth. Their purpose is to strengthen your teeth and protect them from tooth decay. That is the reason why they are added into toothpastes.
Related content: Prescription toothpaste Prevident 5000 has a high fluoride content and that also does not whiten your teeth.
Fluoride cannot chemically oxidize intrinsic stains
Fluoride also cannot chemically oxidize intrinsic stains because the only ingredient which can do that is hydrogen peroxide or its derivative. Fluoride is fluoride and it does not contain any other ingredients such as a peroxide.
Hydrogen peroxide whitens teeth by diffusing through it and oxidizing all of the organic matrices which the intrinsic stains are embedded in. It leaves all of the inorganic matrices intact and only affects the organic component.
Since sodium fluoride doesn’t contain any peroxide, it lacks the capability to remove intrinsic stains.
As evidence you can simply look at all of the OTC whitening products and what they use as a measure for whitening concentration strength. On the labels they will usually list the percentage of hydrogen peroxide or carbamide peroxide. That is the measure by which they use to tell you how strong the whitening product will be.
Example would be Opalesence Go, which comes in two product lines:
- Available in 10% hydrogen peroxide which you wear for 30-60 minutes for 5-10 days.
- Available in 15% hydrogen peroxide which you wear for 15-20 minutes for 5-10 days.
If sodium fluoride was the whitening agent, all of these OTC products would list the percentages of fluoride on their labels instead of the hydrogen peroxide! That makes sense doesn’t it? The fact that they don’t market it means that it is not relevant to whitening.
Fluoride doesn’t whiten teeth but it will strengthen them instead
You may be dismayed that fluoride doesn’t make your teeth white but what it can do is make your teeth stronger. By using fluoride you can can not only make them more resistant to cavities but also reverse small ones.
The mechanism of how fluoride strengthens your teeth is by replacing the hydroxyl ion in hydroxyapatite with a fluoride ion, thus forming hydroxyfluorapatite. This new structure is a more stable apatitic structure. According to research, only about 10% of the hydroxyl groups can be replaced by fluoride so your tooth can never be completely 100% fluorapatite. It will always be a mixture thus being called hydroxyapatite-fluorapatite.
This reaction occurs whenever fluoride interacts with the tooth enamel. Yes, it may not be an oxidation process to whiten the tooth but the fluoride will at least strengthen it. The end result is a stronger and more stable tooth.
Effects of converting hydroxyapatite to fluorapatite:
- Increased resistance to acid dissolution.
- Decreases mineral solubility.
- Increased stability of mineral structure.
- Promotes remineralization to reverse cavities.
We can also reword it and put it another way as to what the effects of fluoride are. According to the CDC, fluoride inhibits demineralization, enhances remineralization, and inhibits bacterial activity in dental plaque.
The Verdict – does fluoride whiten teeth?
Unfortunately fluoride is unable to whiten teeth because it can’t mechanically remove extrinsic stains nor chemically oxidize intrinsic ones. According to the ADA, those are the two types of stains that teeth whitening agents aim to get rid of.
If fluoride did whiten your teeth, your dentist would’ve called it whitening treatment instead of fluoride treatment! The dental community would get a lot less push back about fluoride use if it did have that cosmetic effect. Suffice to say, if it whitened teeth we probably wouldn’t have an anti-fluoride sentiment.
Nonetheless, you should still use fluoride because it makes your teeth stronger and more resistant to tooth decay. Don’t forget that according to the CDC, water fluoridation was one of the top ten public health achievements in the 20th century.
Also it is okay to have your teeth whitened after fluoride treatment. There is just one exception and that is if you’re using a fluoride varnish.