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Calcium Carbonate Vs Hydrated Silica in Toothpaste

Both calcium carbonate and hydrated silica are ingredients in toothpaste which are primarily used as whitening abrasives. However, they do have a couple of additional effects/benefits that you may not be aware of.

Table of contents:

Toothpaste benefits comparison

While both ingredients are more commonly known for their whitening prowess since they can remove teeth stains, they do have other benefits as well.

Calcium carbonate in toothpaste 4 key functions
Tums are made of calcium carbonate!

Calcium carbonate benefits in toothpaste:

  • Whitens teeth by removing stains.

  • Adds a white color to the toothpaste.

  • Thickens the paste.

  • Helps with teeth remineralization.

  • Rebalances oral pH via buffering.

Hydrated silica benefits in toothpastes:

  • Whitens teeth by removing stains.

  • Cleansing agent by removing plaque.

  • Thickens the paste.

  • Compatibility with other ingredients.

  • May help reduce teeth sensitivity.

Silica gel desiccant in food packaging
Silica is used as a desiccant

As you can see, they do much more than just help clean and whiten your teeth. That was a lot more advantages than you probably thought there were, right? Anyway, if I do say so myself, it seems like the calcium carbonate has a much more protective effect based on its benefits. It can help remineralize carious lesions and neutralize mouth acids.

In my opinion, the major advantage for calcium carbonate would be its acid neutralizing and remineralization effect while hydrated silica is very compatible with other ingredients.


Abrasiveness comparison

Calcium carbonate is significantly less abrasive to the enamel than hydrated silica will ever be. This is because the former is a softer mineral while the latter is a harder mineral.

If you wanted a precise objective comparison, look no further than their value on Mohs scale of hardness. The higher the number the harder it is and it can "scratch" the minerals with a lower number.


Mohs Hardness Scale

Calcium Carbonate




Hydroxyapatite (enamel)




From an abrasive standpoint, the hydrated silica is harder and can potentially scratch the enamel/dentin surfaces. However, the calcium carbonate will most likely not be able to damage/harm the teeth.

In conclusion, from an enamel-safety perspective, calcium carbonate would be the safer whitening abrasive out of the two.

Abrasiveness modifying ingredients

Hydrated silica may seem like a poor choice for toothpaste but there are other ingredients which can modify its abrasiveness. These ingredients can either make it safer or even make it more harmful.

How to make hydrated silica less abrasive and safer:

  • Decrease silica concentration. Studies have demonstrated that the higher the concentration of silica in the toothpaste, the more abrasive it is. Therefore to make it safer, you should use less of it.

  • Combine with aluminum oxide. Studies have shown that with the addition of aluminum oxide, it becomes more effective and safer to use.

However, if hydrated silica is combined with pyrophosphates it can increase the abrasiveness and enamel wear. In other words, this is an ingredient combination that makes it worse or more harmful for your teeth!


Disadvantages comparison

Calcium Carbonate

Hydrated Silica


Interferes with fluoride deposition

Very abrasive

Pyrophosphates increase abrasiveness

An often unnoticed disadvantage for calcium carbonate is that it interferes with the deposition of fluoride onto the tooth surface.

  • The calcium ions react with fluoride to form calcium-fluoride (CaF).

  • This reduces the bioavailability of fluoride for enamel use.

Ultimately what that means is this ingredient works against fluoride.

For hydrated silica, the big disadvantage is its abrasiveness. It's a much harder mineral than enamel so it can potentially harm it if used indiscriminately.


Aside from the enamel abrasiveness, both ingredients are otherwise fairly safe to use intraorally.

  • The hydrated silica showed no signs of oral toxicity, non-genotoxic, and also non-carcinogenic.

  • As for the calcium carbonate, it is literally what antacids are made of such as TUMS. Since we all chew it and eat it when we're having stomach acid problems, certainly it is safe enough to just brush with.

After all, both ingredients are FDA approved to be used in dentifrices.


Before I give you my opinion on which ingredient I think is better, I want you to know that there are toothpastes out there which use both of them. Yes, they contain both calcium carbonate and hydrated silica in their formulation.

Ollie toothpaste with calcium carbonate and hydrated silica
Ollie toothpaste with calcium carbonate and hydrated silica

The ollie's toothpaste above is one such example but the Toms toothpaste is probably more well known to you. A lot of the Toms products will include both ingredients. With that being said, I'm personally neutral to both ingredients in that I don't think one is better than the other. It really depends on how you plan on using them such as what ingredients you'll be combining them with.

This article was written by our dentists in Long Island City.


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!

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