Fluoride does not whiten teeth because it can't mechanically remove extrinsic tooth stains nor chemically oxidize intrinsic stains. Nonetheless, it doesn't make it a bad product because it does have other beneficial uses such as when used in conjunction with whitening.
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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, Sensodyne | Hydrated silica | 65 |
Opalesence | Silica | 66 |
Tom's | Calcium carbonate, Sodium bicarbonate, hydrated silica | 49 |
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.
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.
Evidence: Look at all of the OTC whitening products and what they use as a measure for whitening concentration strength. 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: 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! The fact that they don't market it means that it is not relevant to whitening.
Teeth whitening requires extrinsic/intrinsic stains removal
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 doesn't whiten teeth but strengthens them
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, which is more stable.
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.
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.
Fluoride benefits during whitening
Fluoride may not whiten your teeth but it can help reduce teeth sensitivity during the whitening treatment.
Most OTC whitening products will induce sensitivity or gum irritation within 3-4 days of starting treatment. Using a fluoride toothpaste can help minimize the amount of discomfort while you're bleaching your chompers.
However, only stannous fluoride possesses a desensitizing effect. The less expensive sodium fluoride does not possess any tooth desensitizing capability.
Fluoride Side Effects
Fluoride may not whiten but it is very safe and not harmful in low dosages for your teeth. However, high doses can result in fluorosis or mottled enamel.
Side effects:
Fluorosis. A condition where teeth develop white spots due to excessive exposure to fluoride. This leaves an unaesthetic streak or splotches of white spots across the enamel. These white spots are hypomineralizations, which are weakened enamel.
Mottled enamel. A severe form of fluorosis where the white spots start turning into a brown stain. Sometimes pitting can even form on the enamel surface.
Despite these adverse effects, you are unlikely to get them during typical teeth whitening treatments.
Verdict
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.
