https://www.reddit.com/r/askscience/comments/1gydh78/how_does_fluoride_reduce_cavities/
created by We_are_all_monkeys on 23/11/2024 at 23:51 UTC
376 upvotes, 9 top-level comments (showing 9)
Ignoring the political controversy, what's the mechanism by which fluoride reduces cavities?
Comment by Magicspook at 25/11/2024 at 08:13 UTC*
1203 upvotes, 16 direct replies
Finally, a question about inorganic chemistry.
Your tooth enamel is made of a material called hydroxyapatite. It is a type of salt composed of calcium, phosphate and hydroxy ions. Your bones are also ~66% made from this stuff (hence why people say bones are made of calcium, even though in the end, it's only about 10% calcium by weight).
Hydroxyapatite is a good waterproof and hard material, so ideal for your teeth. However, it is weak against acids, which take the hydroxy ion (OH-) and turn it into water (H2O). The structure then crumbles, resulting in cavities.
Another funky property of hydroxyapatite is that it can switch out the ions it is made of. So if you put it in a bath of fluoride (F-), some of those fluorides will kick out the hydroxy ions and replace them in the structure. You cannot see this transformation visually, but the new fluoroapatite structure is much more resistant against acids because it doesnt contain hydroxy anymore, thus protecting your teeth.
This transformation only happens in the outer few nanometers of your enamel, and is somewhat reversible, so it is sadly not a one-and-done solution. You have to reapply the fluoride regularly.
I hope this answers your question. If you have any more, I'm happy to answer them!
Comment by AdarTan at 25/11/2024 at 08:09 UTC
19 upvotes, 0 direct replies
Converts hydroxyapatite in tooth enamel into fluoroapatite. Fluoroapatite is mechanically weaker but more resistant to chemical weathering than hydroxyapatite so the tooth enamel becomes more resistant to the acid excreted by bacteria in the mouth. The fluorine can also react with dissolved apatite in the saliva and because fluoroapatite is less soluble it will fall out of solution and remineralize on the teeth.
Comment by swollennode at 25/11/2024 at 08:21 UTC
26 upvotes, 0 direct replies
Cavity happens when bacteria and acid eats away at the enamel, softening and weakening the teeth.
Fluoride combines with calcium And phosphate creating fluorapetite, which is a hard mineral that forms on the enamel and strengthens.
Fluoride basically remineralize teeth and keep it strong, preventing cavities and tooth decay.
Comment by the6thReplicant at 25/11/2024 at 09:07 UTC
26 upvotes, 0 direct replies
It's important to note that fluoride occurs naturally in any water that has contact with rocks. We can assume that we have evolved to expect some fluoride in our water: whether or not our teeth has also evolved to expect the same is another matter. But in the levels we see in nature our bodies can cope with it very well.
Comment by PsychologicalTry9752 at 25/11/2024 at 19:03 UTC
5 upvotes, 0 direct replies
It’s really important to understand that fluoride occurs naturally in various levels in drinking water. Water fluoridation aims to control the fluoride levels to 0.6 to 0.8 parts per million as this is the minimum level required to provide a dental benefit but low enough to not cause any health problems from excessive fluoride. If the natural fluoride levels are already at this or higher no fluoride is added. Water fluoridation helps people in lower socioeconomic groups greatest as often these groups have diets higher in sugar, poor access to dental care and poorer dental hygiene . The anti- fluoridation movement seems to have originated first in America and was likely as a result of certain groups being opposed to seeing their tax dollars spent on public health. They wrapped up this so called concern on unfounded scaremongering about health side effects. Also it is really important to invest in proper water fluoridation monitoring to make sure it is being used correctly.
Comment by nanakapow at 25/11/2024 at 08:09 UTC
9 upvotes, 0 direct replies
The fluorine binds with the tooth enamel to create a layer of calcium fluoride, which is way stronger and more acid resistant than the natural enamel structure.
Toothpaste includes calcium, together this also helps remineralise existing cavities, filling them in over time.
Comment by sketchdraft at 28/11/2024 at 09:40 UTC
1 upvotes, 0 direct replies
Consider using **hydroxyapatite toothpaste** as an alternative for reducing cavities. While fluoride is commonly found in many dental products—and even naturally present in sharks—hydroxyapatite is a safer and effective option. Although less advertised, it can strengthen enamel and promote oral health without the potential downsides associated with fluoride.
Comment by Ihavepurpleshoes at 27/11/2024 at 05:52 UTC
0 upvotes, 0 direct replies
This is one of the reasons that it is often recommended that we brush our teeth for 2 min – to give the fluoride in the toothpaste a chance to react with the enamel.
Fluoridated drinking water is one of the best public health initiatives ever. Toothlessness was a fact of life for almost all older people before, and that is only after they went through years of pain and decay, losing one tooth at a time until the last few stragglers fell out.
Comment by STEMguyRetd at 26/11/2024 at 02:34 UTC
-6 upvotes, 0 direct replies
Nobody needs fluoride.
Get a brain worm first, then everything gets much clearer. You'll also see things like tariffs much more simply, you know, as a tax that the country of origin has to pay.
Once the worm is in residence, you'll find your neighbors magically agreeing to fund that new fence you want