 
Glycerine in Oral Care: What the Science Really Says
Glycerine — sometimes called glycerol — is one of the most misunderstood ingredients in oral care.
Once dismissed in online forums as a “barrier to remineralisation,” it’s become the focus of widespread misinformation, often traced back to the writings of chemist Gerard F. Judd. But as with many persistent internet myths, those claims are not supported by experimental evidence.
At Truthpaste, we use glycerine in our formulations for its proven functional and oral-care benefits. Here, we take a closer look at what peer-reviewed science really says about this ingredient, how it interacts with the oral environment, and whether it truly affects enamel remineralisation.
What Glycerine Is and Why It’s Used
Chemically, glycerine (C₃H₈O₃) is a trihydric alcohol — a clear, viscous liquid with three hydroxyl (–OH) groups that attract water. This hygroscopic nature makes it an effective humectant, helping toothpaste stay moist and preventing it from drying out in the tube or jar.
Beyond its physical role, glycerine contributes to:
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Moisture retention: maintaining hydration in the mouth. 
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Texture and spreadability: helping the paste distribute evenly across teeth and gums. 
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Stability: supporting a consistent formulation that suspends active ingredients effectively. 
In short, glycerine helps a toothpaste work — ensuring that actives such as hydroxyapatite, xylitol, or botanical extracts remain evenly dispersed and functional during use.
The Origin of the Myth
The notion that glycerine “coats the teeth” and prevents remineralisation is not grounded in scientific research. It appears to originate from the late chemist Dr. Gerard F. Judd, whose writings circulated widely online in the early 2000s. Judd claimed that glycerine left a film over enamel that required “27 rinses” to remove and thus blocked minerals from binding to the tooth surface.
However, these claims were never supported by published data, peer-reviewed research, or experimental verification. No controlled studies have demonstrated that glycerine inhibits calcium or phosphate uptake, or that it forms an impermeable barrier on enamel.
In fact, glycerine is highly soluble in water and saliva, meaning it won't leave a residue on teeth.
What the Science Actually Shows
1. No Evidence of Remineralisation Inhibition
There are no peer-reviewed studies demonstrating that glycerine interferes with enamel remineralisation or ion exchange.
In fact, the opposite may be true: glycerine is water-soluble, readily rinsed, and does not form a polymeric or hydrophobic film on enamel. Unlike certain surfactants or silicones, it does not adhere strongly to hydroxyapatite surfaces. When combined with brushing and saliva flow, residual glycerine is quickly diluted and removed.
2. Compatibility with Active Ingredients
Formulation studies have shown that glycerine can act as a vehicle without reducing the bioavailability of other active ingredients. For example, when used in chitosan-chlorhexidine membranes, glycerine modified mechanical properties but did not alter antimicrobial activity against Streptococcus mutans — one of the main bacteria responsible for tooth decay (Frontiers in Microbiology, 2024).
This suggests that glycerine does not chemically interfere with other oral-care actives — it simply supports texture and stability.
3. Supports Moisture and Tissue Health
In clinical and in-vitro models, glycerine has been shown to retain moisture and soothe oral mucosa:
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A randomized controlled trial on patients with dry mouth found that glycerine provided immediate relief from xerostomia symptoms, although the effect diminished after two hours (European Journal of Oral Sciences, 2020). 
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An in-vitro reconstructed oral mucosa study found that while very high concentrations of glycerine (42–85%) affected cell proliferation, lower levels typical in cosmetic and oral formulations showed no disruption of tissue integrity (Journal of Applied Oral Science, 2019). 
These findings reinforce that glycerine’s humectant properties can be beneficial in maintaining oral comfort — especially for people with dry mouth or irritation.
4. Potential Microbiome Benefits
Recent research shows that Streptococcus sanguinis — a bacterium commonly found in healthy, non-cariogenic oral microbiomes — can metabolise small amounts of glycerol in ways that help it maintain a competitive advantage over cavity-causing bacteria such as S. mutans.
In other words, in small physiological amounts, glycerine may actually help maintain microbial balance rather than disrupt it.
Understanding the Limits
While glycerine contributes useful properties to toothpaste, it’s not a magic ingredient — nor is it a hazard.
It does not remineralise teeth by itself, but neither does it prevent remineralisation when other actives (such as hydroxyapatite, fluoride, or calcium phosphates) are present.
At the concentrations used in toothpaste (typically under 20%), glycerine:
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is non-toxic, 
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rinses away easily, 
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and does not form a barrier to mineral exchange. 
Why Truthpaste Uses Glycerine
Truthpaste formulations are designed around function, safety, and evidence.
We use plant-derived glycerine for its moisture-retaining, texture-enhancing, and microbiome-friendly qualities. It helps distribute active ingredients such as hydroxyapatite and botanical extracts evenly across enamel and gums, improving the delivery of minerals where they’re needed most.
Crucially, our formulations are tested for pH balance, ionic compatibility, and stability, ensuring that remineralisation agents remain fully active and that glycerine plays a supportive—not obstructive—role.
The Takeaway
Misinformation spreads easily, especially when scientific language is taken out of context. Glycerine has been unfairly vilified by outdated, anecdotal claims, but the evidence paints a very different picture.
According to current research, glycerine:
✅ Does not block remineralisation.
✅ Helps maintain moisture and oral comfort.
✅ May support beneficial oral bacteria.
✅ Enhances product texture and stability.
At Truthpaste, every ingredient is chosen for a reason — and glycerine earns its place for both practical and scientific ones.
References
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Andersen, J. et al. (2019). Influence of glycerol concentration on reconstructed human oral mucosa model. Journal of Applied Oral Science, 27(4):e20180412. 
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Petrou, M. et al. (2020). Clinical evaluation of saliva substitutes in xerostomia management. European Journal of Oral Sciences, 128(3):201–210. 
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Chan, A. et al. (2024). Functional properties of chitosan–glycerol–chlorhexidine membranes against oral biofilms. Frontiers in Microbiology, 15:1430954. 
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Ganesan, S. et al. (2023). Glycerol metabolism and hydrogen peroxide production by oral Streptococcus sanguinis. Microbiology Spectrum, 11(4):e00689-23 
Let customers speak for us
from 1909 reviewsAfter using the Trupaste thought that I'd give the mask a go - have been using it for about 2 weeks now and can say that it is doing a great job - my teeth feel smoother and less sensitive!
 
  Happy with the de-sensitising effect after a few weeks use, not quite sure what effect the mask product is having as yet though.
 
  It takes a little time and perseverance to get used to using a paste from a jar with a spatular but the product itself is doing its job just as well as products from a tube. I can see the jar will last a long time which outways the initial cost. The biggy for me is to find a toothpaste that is not using plastic! I will continue to buy this product.
 
  I’ve noticed a difference in the colour of my teeth, they don’t look so yellow.and great that there is no fluoride in the product I’m using.
 
  Definitely helped my sensitivity without a doubt
 
  I wanted a more natural toothpaste and thought I’d try truthpaste and am pleased to say that it lives up to all my expectations and more, it leaves a lovely fresh taste in the mouth.
 
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  Brilliant my teeth have never felt so fresh, clean and healed. Thank you and flouride free.
 
  After a few days of following the instructions I looked at my teeth in the mirror and was shocked to see that my teeth were whiter. 🙏👌
 
  This floss is very effective. It's thicker and grippier than other flosses, so it gets the job done thoroughly.
 
  This mouthwash is the best I have tried. It really cleanses and has a great taste. It is strong without being overpowering. I will be sticking to this in the future.
 
  These are the perfect size for travel; in a child friendly tin and pocket sized so we won’t ever be without! Love the new hydroxyapatite toothpaste the most!
 
  I love all of my Truthpaste products and the Bamboo Charcoal Floss is the best floss I’ve ever used. I actually feel it’s not only cleaning my teeth efficiently, but it’s also helping them to stay healthy. I ordered the original and the two refills. Will do so again, soon. Thanks guys!
 
  I bought this for my grand children. One age 2 and the other 15. They both like it and are happy to use. Especially my older grand daughter when I explained about all the lovely ingredients.
 
  Like mint flavour and teeth feel clean
 
   
  
          