Does Glycerin in Toothpaste Block Remineralization? [Here’s What the Research Says]

Can the glycerin in toothpaste really coat our teeth and block their natural ability to remineralize?

Over the years, we’ve received a lot of questions about the safety of various oral hygiene product ingredients, like xylitol, baking soda, and fluoride.

But one subject we hadn’t explored deeply (until now) is the potential risks of using glycerin in toothpaste.

So today, we’re going to take a closer look at whether glycerin in toothpaste blocks remineralization.

We’ll explore:

• why glycerin might be included in a toothpaste;
• where the idea of it blocking remineralization came from; and
• what the clinical data says about whether or not it really blocks remineralization.

Let’s start by unpacking what glycerin is and what role, if any, it can play in a toothpaste formula.

What is glycerin, and what does it do in a toothpaste formula?

Glycerin (also known as “glycerine” or “glycerol”) is a sugar alcohol that’s a natural component of fats. That’s why we see it peeking through in the word “triGLYCERide” (the most common type of fat in the body and in foods).

Commercially produced glycerin is used in medicines, foods, soaps, beauty products, and oral health products. It’s often derived from plant oils and animal fats. It can also be derived from petroleum, but this production method is less common.

Glycerin has a sweet flavor and a thick, smooth, and syrupy consistency. If there’s a lot of it in a formula, it’s most likely being used as a sweetener, preservative, or filler, which we’ll discuss more in a bit.

However, in skincare and toothpaste formulas where glycerin is not one of the top ingredients, it tends to function as a binder (meaning it helps prevent the formula ingredients from separating) or as a humectant (meaning it helps preserve moisture and prevent the product from drying out).

In other words, glycerin helps maintain a product’s unified, hydrated, and creamy texture.

Now that we know what glycerin is and why it might be used in toothpastes, let’s turn our attention to the origin story behind the claim that glycerin blocks tooth remineralization…

What’s the backstory behind the idea that glycerin blocks tooth remineralization?

Where did this idea come from anyway?

All accounts of this idea that glycerin coats the teeth and blocks remineralization appear to point back to Dr. Gerard Judd, who taught chemistry for many years at Phoenix College in Arizona.

In the 1990s, Dr. Judd self-published a book titled, Good Teeth Birth To Death.

The book doesn’t mention “glycerin”, but it does reference “glycerol” twice: once in the Index, and once on page 34 when Dr. Judd briefly advises against using toothpastes that contain glycerol (without providing any additional information or evidence supporting his stance).

Then in 2001, Dr. Judd wrote a letter to his followers. In it, he said, “Reenamelization of the teeth occurs when they are clean. All toothpastes make a barrier of glycerine on the teeth which would require 20 rinses to get it off.”

Dr. Judd added a little more information in a 2002 letter to the government in which he said, “Glycerine in all toothpastes is so sticky that it takes 27 washes to get it off. Teeth brushed with any toothpaste are coated with a film and cannot properly reenamelize.“

But neither his book nor his letters appear to include any studies or evidence to back his claims about glycerol or glycerin(e).

Nevertheless, the idea spread, and many influencers in the wellness sphere began speaking out against the use of glycerin in oral health products.

OraWellness’ evolving stance on glycerin…

For some time, this claim even impacted our own decisions here at OraWellness.

We hadn’t explored the scientific literature on glycerin, but we had heard about Dr. Judd’s warnings against it. Since we didn’t know any additional information about it at the time, out of precaution, we chose not to include glycerin in our HealThy Mouth Blend or Shine formulations, and we also encouraged our community to avoid using glycerin in the mouth.

However, after talking with several chemists about this over the years, we started questioning Dr. Judd’s perspective.

All of the chemists who we’ve asked about the risk of glycerin coating teeth and inhibiting remineralization have told us the same thing: it’s simply not possible for glycerin to coat teeth because glycerin is highly water soluble.

Even if we didn’t swish with water after exposing our teeth to glycerin, it still couldn’t leave a coating because our saliva would easily wash it away.

With our doubts mounting, we turned to the published literature to see what the clinical data says about glycerin inhibiting remineralization…

What does the research say about glycerin preventing remineralization (and its other risks and benefits for oral health)?

In our dive into the literature, we first tried to find proof to support Dr. Judd’s stance.

To date, we have found no clinical research to back up his claim.

As of the time we’re writing this, PubMed has over 2000 entries on their database for the searches “glycerin oral” and “glycerin remineralize”, but we have not found a single study that substantiates Dr. Judd’s claim that glycerin inhibits enamel remineralization. Not a single one.

Impact on enamel microhardness…

We did find one study that showed that glycerin had a slight negative impact on enamel and dentin microhardness.

It even says, “It could act as an adsorbed layer barrier to artificial saliva and to a remineralizing effect,” which sounds like we might have found data to back up Dr. Judd’s claim, right?

Not the way we see it. Here’s why…

The statement is just a quick, single sentence that was mentioned almost as if in passing on the second-to-last page, but it wasn’t the point of the study, so there’s no data backing it up.

Just like Dr. Judd’s claims, the researchers provide no substantiation for this statement, which is odd given that it’s common practice for researchers to link to other studies to support their claims.

Also, the purpose of this study was to evaluate several ingredients of conventional teeth bleaching agents, based on a clinical protocol that “. . . employs a bleaching agent in a tray for two to eight hours during the day or night.” And the researchers used fragments of extracted teeth (not teeth that were still in people’s mouths).

The fragments “. . . were exposed to the treatment agents eight hours a day for 42 days . . . and soaked in individual closed vials with 13.5 mL of artificial saliva,” and that artificial saliva “. . . was changed every two days.”

While it might be a normal clinical protocol to keep conventional bleaching agents on the teeth for long periods of time, it would be virtually impossible to try to keep toothpaste on the teeth for 8 hours.

And even if this study had been highlighting toothpaste ingredients instead of bleaching agent ingredients, there would still be another factor to consider: oral clearance.

What is oral clearance?

In the world of dentistry, “oral clearance” happens whenever we produce saliva (or even drink water) and then swallow it. This process helps us move things out of the mouth.

The average person produces and swallows anywhere from ½ to 1 ½ liters of saliva per day. That’s going to result in a lot more turnover—a lot more oral clearance—than the bleaching agent study‘s 13.5 mL of artificial saliva that was changed every two days.

So, while this particular study did show that glycerin had a slight negative impact on enamel and dentin microhardness, because the focus was on bleaching agents, we’re finding that the methods and results can’t really be used to substantiate Dr. Judd’s claim about the alleged dangers of glycerin in toothpaste.

Does glycerin cause enamel erosion?

We also found a study that tested a few types of mouth swabs that are typically used on bed-ridden hospitalized patients. The options that contained glycerin caused some enamel erosion.

However, this was an in vitro study of “…a bovine enamel model system.”

In other words, once again, the teeth that these products were tested on weren’t in someone’s mouth, where saliva and beverage consumption might help with oral clearance.

Also, the study states, “Specimens were incubated for 4 hours in the test solutions…” Again, that’s an unrealistic amount of time for glycerin to sit on our teeth in real life.

Finally, it’s worth noting that the glycerin-containing swabs referenced in the study also contain other, potentially acidic ingredients, like sodium benzoate and water (which, when combined, produce benzoic acid), citric acid, and lemon flavoring. We don’t know the pH of the overall swab formulas, but of course, acids erode tooth enamel.

Could glycerin actually be a beneficial ingredient in a toothpaste?

Although we didn’t find any studies that substantiated Dr. Judd’s claim that glycerin prevents tooth remineralization, and the studies we found that cited other potential drawbacks of glycerin don’t really represent the way most folks would use glycerin in their mouth, we did find some research that suggested glycerin could potentially have a couple of small benefits.

There is some data that suggests that high levels of glycerin can inhibit bacterial accumulation. But again, the research wasn’t focused on the mouth, and since our saliva washes away glycerin so easily, we think that it’s unrealistic to try to use glycerin to inhibit bacterial accumulation in the mouth.

We did find a study that used a toothpaste that contained xylitol and glycerin to reduce the population of strep mutans (the primary thug bug implicated with initiating the tooth decay process). However, since research has already established that xylitol itself inhibits strep mutans, we really can’t say whether the glycerin played a part in the strep mutans reduction, or if the benefit came from the xylitol alone.

So, does all of this mean that glycerin should play a central role in toothpaste formulas?

Well, in our opinion, not really. Here’s why…

Should glycerin be a main ingredient in toothpaste formulas?

Since we couldn’t find any clinical data showing that glycerin inhibits our ability to remineralize our teeth, from our view, including some glycerin to help stabilize the formula and texture isn’t a problem (as long as it’s not sourced from petroleum).

But, there’s really no good reason why glycerin should be one of the top components in a toothpaste formula.

How can we tell if it’s a top component? Look at the product’s “Ingredients” list.

Manufacturers are required to list product ingredients according to their quantity in the formula. On any product label, the first ingredient in the list has the greatest quantity in that formula, and the last ingredient has the smallest quantity.

Interestingly, if we look at the ingredients for many of the toothpastes on the market, we’ll find that glycerin is normally pretty high on the list, in many cases, even #1. Why is that?

Most toothpaste manufacturers make the base of their formulas out of glycerin because it’s sweet and cheap.

It’s a cost-effective way for companies to fill the tube. But, from our research, it doesn’t appear to serve any beneficial role for the person who uses the product, so it’s not providing the best ingredients possible to help the user navigate their path to optimal oral health.

So the takeaway here is this…

It’s wise to get into the habit of carefully evaluating the ingredient labels on anything we’re going to put into or onto our bodies (including oral hygiene products).

To provide the best oral health support, as we check out toothpaste options, we can make sure:

1. the top ingredients aren’t just cheap fillers like glycerin;
2. any health-supporting ingredients in the formula are in high enough concentrations to be effective, not just sprinkled in like pixie dust so the company’s marketing team can claim it’s in the formula; and
3. the product contains no health-undermining ingredients that could cause “down-stream” problems in the body.

What about you?

What was your stance on glycerin in toothpastes? Did you already know where this “glycerin preventing remineralization” myth came from and that it wasn’t supported by research? Were you fooled (like we were!) into believing it at first? What, if anything, was new information for you? Please share your experiences and/or what you learned in the comments below!

And speaking of remineralization, if you’d like research-backed strategies to stop tooth decay and cavities, download your FREE copy of our eBook, “How to Stop Tooth Decay and Remineralize Your Teeth”.

Until the next time, remember to show the world your SMILE!

Are you a visual learner?

Here’s the same information from this article, but in video format:

Helpful, Related Resources:

• Is Glycerin in Toothpaste Bad for Your Teeth? Does Glycerin Block Remineralization? [Here’s What the Research Says]
• Is Xylitol Safe to Brush with? [article]
• Is Baking Soda Safe to Brush With? [article]
• Is Fluoride Safe to Use? [article]
• How to Tell if Your Oral Hygiene Products are Holistic or Not [article]
• How to determine if a toothpaste ingredient is safe to use in the mouth? [article]
• How to Stop Tooth Decay and Remineralize Your Teeth [FREE eBook]
• HealThy Mouth Blend [product solution]
• What’s in the HealThy Mouth Blend? (and why is it so effective?) [article]
• Are essential oils safe to use in the mouth? [article]
• Shine Remineralizing Tooth Whitening Powder [product solution]
• How Does Shine Work?
• Can I use the HealThy Mouth Blend and Shine together? [article]
• How to make a DIY remineralizing tooth powder (that really works) [article]

Other Resources:

• PubMed
• Dr. Judd’s book, Good Teeth, Birth to Death
• 2001 letter from Dr. Judd to his followers AND his 2002 letter to the government
• Basting RT, Rodrigues AL Jr, Serra MC. The effect of 10% carbamide peroxide, carbopol and/or glycerin on enamel and dentin microhardness. Oper Dent. 2005 Sep-Oct;30(5):608-16. PMID: 16268396.
  • Full study: https://www.researchgate.net/publication/7500507
• Iorgulescu G. Saliva between normal and pathological. Important factors in determining systemic and oral health. J Med Life. 2009 Jul-Sep;2(3):303-7. PMID: 20112475; PMCID: PMC5052503.
• Meurman JH, Sorvari R, Pelttari A, Rytömaa I, Franssila S, Kroon L. Hospital mouth-cleaning aids may cause dental erosion. Spec Care Dentist. 1996 Nov-Dec;16(6):247-50. doi: 10.1111/j.1754-4505.1996.tb01548.x. PMID: 9582698.
• Saegeman VS, Ectors NL, Lismont D, Verduyckt B, Verhaegen J. Short- and long-term bacterial inhibiting effect of high concentrations of glycerol used in the preservation of skin allografts. Burns. 2008 Mar;34(2):205-11. doi: 10.1016/j.burns.2007.02.009. Epub 2007 Nov 26. PMID: 18037568.
• Svanberg M, Birkhed D. Effect of dentifrices containing either xylitol and glycerol or sorbitol on mutans streptococci in saliva. Caries Res. 1991;25(6):449-53. doi: 10.1159/000261409. PMID: 1810657.
• Sahni PS, Gillespie MJ, Botto RW, Otsuka AS. In vitro testing of xylitol as an anticariogenic agent. Gen Dent. 2002 Jul-Aug;50(4):340-3. PMID: 12640850.

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