Hydroxyapatite toothpaste vs Fluoride

Updated: Aug 15

Are you worried about the dangers of fluoridated toothpaste and looking for an alternative? This is your guide to remineralization and demineralization of your teeth.



So you've just finished your charcoal toothpaste craze and now all of a sudden you're seeing ads for this new kind of oral dentrifice aka toothpaste. Are you wondering if its actually effective and if so, how does it work? Can it dethrone the incumbent fluoride toothpaste?


Table of Contents:



What is Hydroxyapatite (HAp)?

It is actually a naturally occurring mineral form of calcium apatite that makes up the bulk of our teeth and bones! The chemical formula for it is Ca10(PO4)6(OH)2:

  • Approximately 90% of our teeth's foundation is comprised of it.

  • It makes up about 60% of our bones.

As you can see, it is very important to our body. It is also because our teeth have the highest concentration of hydroxyapatite that makes it the hardest substance in our body. It is harder than bone with a score of five on the Mohs hardness scale. Your enamel is harder than steel albeit more brittle. That means you can't scratch it with a fork but you can chip it biting into it!



Who invented hydroxyapatite toothpaste?

Originally, it was NASA that first proposed a synthetic hydroxyapatite in order to counteract the weakening of teeth and bones in astronauts. The astronauts were losing minerals in their hard tissues because of being in space for an extended period time in the absence of gravity.


A Japanese company, Sangi Co., Ltd, purchased the patent from NASA in the 1970s and launched the first iteration in 1978 called Apadent, which contained nano-hydroxyapatite. Then in 2006, a european version came onto the market and most recently a couple of US brands have followed suit. These are all natural hydroxyapatite toothpastes.



Does this stuff actually work?

According to this study in 2019, it compared the remineralization of hydroxyapatite toothpaste 10% vs its fluoride counterpart 500 ppm F- in children with cavities and it is effective. What it found was:

  • Both toothpastes showed a reduction in the carious lesion depth with remineralization.

  • But there was no statistical difference between the two in remineralization or teeth decay reduction depth.

  • The HAp did appear to produce a more homogeneous layer of remineralization throughout the entire thickness of the lesion.

  • The fluoride remineralization was most effective only at the outer 30 μm of the decay while leaving most of the body intact.

Ultimately, the conclusion was that it was equal to but not worse than fluoride. It did however end on a positive note since HAp had the possibility of achieving a fuller remineralization due to the more homogeneous layer. Possibly increasing the dosage or continued usage could've achieved it.



How does hydroxyapatite toothpaste work?

It is bioactive and biomimetic so it is very natural; it works sort of similarly to fluoride but without it, kind of. It still follows the principles for remineralization and demineralization of tooth structure.

  • Creates a synthetic coating over the tooth.

  • Fluoride will re-enforce the existing layer rather than create a new one.

  • Elevates the concentration of calcium and phosphate ions in saliva, plaque, and tooth surface which are used in the remineralization process.

  • Basically acting as a reservoir for the ions

  • Adsorbs to the bacterial cell wall, causing them to co aggregate thus facilitating biofilm removal and hindering formation.

The effects:

  • The new layer has less particles than the natural enamel layer so it is less porous.

  • The new layer is also resistant to brushing!

  • The layer is very homogeneous because it is smoothly leveled and repaired.

  • Also shown to decrease dentin sensitivity so it works as a sensitivity toothpaste.

Last but not least, it does not prohibit any residual fluoride ions around from transforming the hydroxyapatite to fluorapatite, which is more resistant to acid attacks. Therefore, it could potentially have a re-enforced existing layer along with a new layer on top as well.



How does a fluoridated toothpaste work?

Fluoride fights cavities and makes teeth stronger via direct contact with the teeth. This means that the effect is topical and not systemic. Here are its effects:

  • Inhibits demineralization - the fluoride adsorb to the surface crystals and protects it from dissolving. The sources comes from your water drinking water supply and toothpastes.

  • Promotes remineralization - the fluoride that adsorbs to the surface of the demineralized tooth, attracts and forces the calcium and phosphate back into the tooth.

  • Inhibits bacterial activity - in an acidic environment, fluoride combines with hydrogen to form HF, which can cross the bacterial cell wall. Inside, it breaks back down releases fluoride which interferes with essential enzymatic activity.

  • Fluoride reservoir - Fluoride remains in the mouth via reservoirs such as teeth, soft tissue, salivia, and plaque. These get released back into your mouth to fight decay when they're needed.



How does fluoride make teeth stronger?

Let's review the actual process of how fluoride strengthens teeth or rather bones in general. The hydroxyapatite when it comes into contact with fluoride, the hydroxyl groups gets replaced by the fluoride ion and becomes fluorapatite. This new structure has:

  • Increased stability

  • Increased hardness

  • Reduced solubility



Fluorapatite
Fluorapatite

As you can see, it becomes a bigger structure and consequently much more stable and resistant to acid attacks. Just remember: Hydroxyapatite ~> Fluorapatite



The remineralization and demineralization process


Why do our teeth demineralize?

The bacteria that are always present in our mouth excrete acid whenever they consume sugar. The acid will dissolve the hydroxyapatite crystals from the subsurface of the tooth.


How does it remineralize?

Our body then tries to repair itself by remineralizing the areas that were attacked by acid. The process is assisted by fluoride and uses calcium and phosphate ions to do the job.


Under normal conditions when the pH in the mouth is at its resting leveling, the saliva should be supersaturated with calcium and phosphate ions. This makes it difficult for cavities to form. But when you consume a lot of sweets, carbohydrates, or anything that will drop the pH level of the mouth down, that is when tooth decay starts to form. This level is usually around 5.5, in the acidic range.


Normally, the lower the pH, the greater the concentration of calcium and phosphate would be needed to reach the saturation point for remineralization to occur. This pH point is called the critical pH. The critical point is where remineralization can be in equilibrium with demineralization.

  • The critical pH for hydroxyapatite is 5.5

  • The critical pH for fluorapatite is 4.5

This means that teeth that have been exposed to fluoride have a lower threshold to begin its natural repair process. That is where the benefit of fluoride comes from.



The history of fluoride

It all began as an observation by Dr. Frederick McKay in 1901 when he moved to Colorado Springs, Colorado to open up his dental practice. Once he was there, he noticed that a lot of the community residents had brown stains on their teeth. He could find no literature that would explain such a phenomenon so he took it upon himself to investigate the cause.


Then in 1909, a colleague, Dr. G V Black, who was intrigued came to help him. What they discovered was that there was something in the water supply that caused the stained teeth but interestingly enough, these stained teeth appeared to be more resistant to cavities. They couldn't figure out what that something was but they published a report on it.


It was around the 1930s when a chemist, Churchill, picked up the report and examined the water samples from the reported communities and discovered fluoride present in the water. No one has ever heard of fluoride being naturally present in the water before so they redid the test but it came back the same.


Then it wasn't until around the 1940s that the NIH started testing water fluoridation. They ran a large scale water fluoridation study in Grand Rapids, Michigan by adding fluoride to the community drinking water to see if it fights tooth decay. After that, the rest was history and it only took about half a century to figure out fluoride.


Consequently water fluoridation became one of the ten greatest public health achievements in the 20th century.



A bonus use of hydroxyapatite

An interesting effect of HAp is the possible use in defluoridation. When placed into drinking water, it forms fluorapatite, which basically removes the fluoride ions from being staying in the water.


Unfortunately, after this process occurs the pH level of the water rises and the phosphate concentration also increases, therefore making the defluoridated water to be unfit for drinking. Further investigation and studies should be warranted.



Our predictions

In this study, the researchers noticed that even in the experimental group where they used the HAp toothpaste, some of the benefits of a fluoride toothpaste were still being used even though the HAp did not contain any fluoride.


HAp is suppose to only form a new layer on top while fluoride does not but rather strengthens the existing layer.


Due to residual fluoride in the subjects saliva, plaque, and teeth, the fluoride effect of re-enforcing the existing layer was still taking place. This means that the hydroxyapatite toothpaste had a DOUBLE protective effect.


Therefore, we believe that with further studies, HAp will eventually completely eclipse just a fluoride toothpaste and it is only a matter of time. It elicits an effect that the fluoride does not, which is adding an extra layer.


With that said, we do not believe that fluoride will be driven out of society. It is naturally occurring in water supplies at varying concentrations. It also offers a benefit that HAp cannot do, which is strengthening the existing layer of enamel.


Our prediction is that once HAp becomes mainstream, we would not get rid of fluoride in our water supplies but we will decrease the fluoridation level so that it becomes even safer.


There is rarely anything in this world that is truly 100% good or 100% bad. Everything should be taken in moderation.

  • Tylenols are good for headaches but if you take the whole bottle, it'll be the last headache you'll ever have.

  • Water is necessary for all life but if you drink 50 gallons, you will enter a new life.

  • Fluoride can be toxic at concentrated levels, but it is completely safe at low levels. The lower the level, the better.


Our recommendations for the fluoride alternative debate

Our dentists in long island city definitely do recommend the use of natural hydroxyapatite toothpaste.

  • If you would prefer to use it over your regular fluoride toothpaste, we have no qualms about it at all.

  • If you have a toddler, we definitely do think you should use it since it eliminates the possibility of fluoride toxicity. This is a bigger concern in children under six. After six years old, you can switch back to fluoride if you wanted to.

  • Definitely check your community's water fluoridation level here.

With that said, we do believe that this debate or fluoride conspiracy does need to come to an end because when used properly, fluoride is very effective and cost efficient for what it can do. Here is a cost analysis of fluoride vs hydroxyapatite toothpaste.

  • It costs approximately $1 for every person per year to fluoridate the water supply

  • For colgate total toothpaste, you can get a 4 pack of 4.8 oz on amazon for $13 which out to $3.25 per tube.


Here are some examples of the natural hydroxyapatite toothpastes on amazon and their prices:

  • Davids - $10 for 5.25 oz

  • Apagard - $17.50 for 3.52 oz

  • Perioscience - $19 for 3 oz

  • Kinder Karex - $8 for 2.3 oz

  • ELIMS - $14 for 4 oz


Just some examples but as you can see, the cost is significantly greater. Hopefully when it becomes more widely available and production costs come down... it'll be able to reach an even bigger audience but for now it seems like it only appeals to a small niche.


This is definitely not a workable solution for countries that don't do as well as the US. There is no way poorer countries would be able to afford that.



The dangers of fluoride

Fluoride in low concentrations is safe but when it reaches excessive levels such as above 4.0 ppm (parts per million) it could be hazardous to your health. Most communities have a water fluoridation level of around 0.7-1.0 ppm, which is below the toxic level.


There are also other issues with excessive fluoride:

  • Skeletal fluorosis

  • Thyroid problems

  • Neurological problems

  • Acne and skin problems

  • Fluoride poisoning - abdominal pain, excessive saliva, nausea and vomiting, seizures and muscles spams


The most notable dental problem with excessive fluoride is fluorosis, where white streaks start forming on your teeth. Sometimes it can



Conclusion

To wrap it up, yes our long island city dentists do believe hydroxyapatite toothpaste is a viable alternative to fluoridated toothpaste! The only downside is the obvious cost associated with it so whether you want to make the switch would be up to you.


Our long island city dentists do have a strong recommendation for using it if you have children the ages 6 or below. Most likely, the amount of daily fluoride would most likely not be harmful to them but there is no need to take the risk if a viable alternative is available.


Other main points:

  • HAp adds an additional protective layer on top of the tooth which fluoride does not.

  • Does not prevent residual fluoride from strengthening underlying layer of enamel.

  • Serves as a reservoir of calcium and phosphate which are the building blocks for remineralization. Fluoride does not.reserve

  • May potentially fully reverse a small cavity. Fluoride only reaches outer 30 μm.

Our forecast is that once the prices come down, there will be large scale adoption and then we can most likely reduce the fluoridation level in our water supplies.


David Chen 200 x 200.jpg

About the author: Dr David Chen, DDS

Hello, I'm Dr Chen and I'm an actively practicing dentist in Long Island City, NY. I graduated from Columbia University College of Dental Medicine in 2016 but prior to going to dental school I was already working in the dental field. It's been more than a decade since I first got to know dentistry and let me tell you, time flies by quickly. Since then I've developed a fondness for writing, which is how this all got started!

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Medical Disclaimer:

This blog is purely meant for information purposes and should not be used as medical advice. Each situation in your mouth is unique and complex. It is not possible to give advice nor diagnose any oral conditions based on text nor virtual consultations. The best thing to do is to go in person to see your dentist for an examination and consultation so that you can receive the best care possible.

The purpose of all of this oral health information is to encourage you to see your dentist and to inform you of what you may expect during your visit. Due to the unfortunate nature of dentistry, there isn't really any true home remedies that will get rid of dental problems. Roughly 99.99% of them require in-person intervention by a healthcare professional.

Hint: That is the reason why you can't eliminate seeing dentists in your life!