The Technology
Stronger enamel, grown from cacao.
Rennou® is a proprietary combination of theobromine, the active compound in cacao, with a source of calcium and phosphate. Together they set the stage for enamel crystals larger and more acid-resistant than fluoride builds.
Shop Theodent
The mechanism, in three steps
How Rennou® builds enamel
Everyday acids soften enamel
Acids from the foods and drinks you enjoy dissolve tiny amounts of the hydroxyapatite crystals that make up enamel.
Rennou® delivers the building blocks
Rennou® is a proprietary combination of theobromine with a source of calcium and phosphate. On contact, it sets the stage for enamel crystal growth.
Larger crystals grow
Theobromine guides the calcium and phosphate into hydroxyapatite crystals that are larger and more acid-resistant than ordinary enamel.
Rennou® pairs theobromine with a source of calcium and phosphate to set the stage for crystal growth. The result is enamel built from larger, more acid-resistant crystals.
Rennou® vs. the alternatives
Three routes to stronger enamel
| Rennou® | Fluoride | Nano-hydroxyapatite | |
|---|---|---|---|
| How it works | Theobromine plus calcium and phosphate set the stage for crystal growth | Forms fluorohydroxyapatite on the surface | Deposits particles that must dissolve first |
| Active concentration | Below fluoride levels | 1,000 to 1,500 ppm | 50,000 to 100,000 ppm |
| Poison Control warning | None required | Federally required | None required |
| Patent protection | Patented, Theodent only | Commodity | Commodity |
| Building blocks | Theobromine, calcium, and phosphate | Added fluoride ion | Synthetic particles |
Why concentration matters
How much active it takes
Nano-hydroxyapatite brands flood the paste with up to 100,000 ppm of a relatively inert particle and wait for it to dissolve. Rennou® works at the ionic level, so it needs far less material. Figures from Theodent's published data and existing site copy.
It Started with an Accident
Many of our most important medical discoveries were not planned. Penicillin came from a contaminated petri dish. X-rays were found while studying cathode rays. Theodent has a similar origin story.
In the early 1990s, Dr. Tetsuo Nakamoto, a researcher at the LSU School of Dentistry, was studying how caffeine affects teeth when he noticed something odd about a closely related molecule called theobromine, which occurs naturally in cacao. Where caffeine damaged enamel, theobromine did the opposite. It appeared to grow the hydroxyapatite crystals that make up tooth enamel, producing crystals that were larger and more acid-resistant than those formed by fluoride. Earlier research had noted that cacao seemed to have some protective dental effect, but no one had identified the specific mechanism or pursued its application in oral care.
Dr. Nakamoto did. His team isolated theobromine from cacao, stripped out the fats and sugars you'd find in processed chocolate, and combined it with calcium and phosphate in a specific ratio. The result is Rennou, the patented active ingredient in every Theodent product. The formulation and its application to oral care are covered by patents that Theodent holds exclusively.
The case against the default
Why not fluoride?
Fluoride has been the default in oral care for over a century. It works by forming fluorohydroxyapatite crystals, which are more acid-resistant than normal enamel. On that narrow measure, it is effective. But fluoride is also a neurotoxicant, and every fluoride toothpaste sold in the United States is required by the FDA to carry a Poison Control warning.
Under federal review
In 2024, the government's own scientists took the neurodevelopmental question seriously.
After years of review, the National Toxicology Program, part of the National Institutes of Health, published a systematic review of fluoride and children's brain development. It concluded with moderate confidence that higher fluoride exposure is associated with lower IQ in children. Read the monograph ↗
The same question is being litigated. In Food & Water Watch v. EPA, a federal district court ruled in September 2024 that fluoridation at the level used in American drinking water poses an unreasonable risk under the Toxic Substances Control Act, and ordered the EPA to respond. That order was vacated on procedural grounds by the Ninth Circuit in May 2026 and returned to the district court. The underlying scientific question has not been settled either way, and the case continues.
Both the monograph and the lawsuit concern fluoride in drinking water, at exposures above what brushing delivers. Neither is a finding about toothpaste, and we are not presenting them as one. We include them because they turn on the same question any parent is entitled to ask: how much fluoride is a child taking in altogether, and from where. For a child who swallows a third to three-quarters of what is on the brush, twice a day, toothpaste is part of that answer. Theodent takes it out of the equation.
Rennou® produces larger, more acid-resistant crystals than fluoride, without any of these toxicity concerns.
Why Not Nano-Hydroxyapatite?
Most fluoride-free toothpastes on the market today use nano-hydroxyapatite, or nHA. It's worth understanding what nHA actually does, because the mechanism is fundamentally different from Rennou's.
Remineralization requires calcium and phosphate in ionic form. Ions are what integrate into your enamel's crystal lattice. Whole particles can't do that. They have to break down first. nHA is made up of synthetic hydroxyapatite particles that are applied to the tooth surface, where they sit until they dissolve into their ionic components. The problem is that this dissolution is slow and inefficient, which is why nHA toothpastes need to use enormous concentrations to show results. Most nHA formulas run between 5% and 10% of the total paste, which works out to roughly 50,000 to 100,000 ppm of the ingredient. For context, fluoride toothpaste uses 1,000 to 1,500 ppm. nHA isn't really acting as an active ingredient at those levels. It's more like flooding the zone with a relatively inert material and hoping enough of it breaks down to be useful.
Rennou takes the opposite approach. Its active molecule is present at a concentration well below that of fluoride, yet clinical data shows 71x more effective remineralization (Caries Research, 2013). That's possible because Rennou works at the ionic level from the start. Rather than waiting for particles to dissolve, it pairs theobromine with a source of calcium and phosphate to set the stage for crystal growth.
There's a market distinction worth noting as well. nHA is a commodity ingredient with no IP protection. Any company can buy it and put it in a tube. Rennou is patented, and the patents are held by Theodent. That's why you won't find it in any other product.
Safe if swallowed. No warning label.
Rennou® carries the US FDA's highest food safety designation, GRAS (Generally Recognized as Safe). At the concentrations present in Theodent toothpaste, Rennou® poses no toxicity risk and the product is safe if swallowed during normal use. That is why Theodent products do not carry a Poison Control warning.
Theodent Kids
Young children swallow most of their toothpaste. With fluoride that is serious enough to warrant a federal warning label. With Theodent it is not. Kids comes in flavors children are genuinely enthusiastic about, which helps with the twice-a-day routine, and you do not need to supervise every spit.
Theodent Classic
Formulated for adults who want a premium oral care product backed by actual clinical research, built on the same Rennou® technology and no fluoride.
Theodent 300
Our highest concentration of Rennou®, for adults who want the most of what the technology can do.
The published studies are listed on our Clinical Evidence page, and the peer-reviewed literature on theobromine and remineralization continues to grow.
Ready to try it?
Achieve peak oral hygiene without fluoride. The solution has existed in nature all along: cacao! An organic compound proven to contain extraordinary oral health benefits was discovered in the fruit of the cacao tree. Theodent Classic toothpaste harnesses the power of this organic compound through Rennou®, a patented technology available only in Theodent products. Strengthen your smile with Theodent Classic.
