Why it ranks first
Almost every fluoride-free toothpaste worth considering is built around hydroxyapatite, the calcium phosphate mineral that makes up the overwhelming majority of tooth enamel. The interesting differences between brands are not whether they use it, but which particle size they use, how much of it they include, and what else they put in the tube alongside it.
Klyyr is the only paste in this ranking that uses both nano and micro hydroxyapatite in the same formula. That matters because the two behave differently. Nano-scale particles are small enough to enter the microscopic defects that form on enamel as it demineralizes, while larger micro-scale particles remain on the surface and contribute to the smooth, polished feel you notice after brushing. Brands generally pick one. Using both is a more expensive way to build a formula and it is the main reason Klyyr takes the top score in our remineralization category.
The rest of the formula does not undercut that decision, which is the more common failure mode. Plenty of pastes lead with hydroxyapatite and then add sodium lauryl sulfate for foam, or lean on flavor systems that require a long tail of ingredients nobody can identify. Klyyr keeps the list short, skips SLS, and skips artificial dyes and sweeteners.
The formula
The supporting cast is conventional in the best sense. Xylitol is a sugar alcohol that oral bacteria cannot metabolize into acid, and it appears in essentially every credible fluoride-free formula for that reason. Hydrated silica and calcium carbonate handle mild abrasion. Glycerin controls the texture and keeps the paste from drying out in the tube.
What is absent is as informative as what is present. No sodium lauryl sulfate means less foam than a drugstore paste, which takes a few days to get used to and is a genuine benefit for anyone prone to canker sores or with a history of mucosal irritation. No artificial dyes means the paste is the off-white of the mineral itself rather than a manufactured brightness.
Using it
Hydroxyapatite pastes feel different from fluoride pastes and it is worth setting expectations. The foam is minimal. The mint is present but restrained, closer to a real leaf than to the sharp cooling of a mainstream mint, and it does not ruin the taste of anything you eat or drink shortly afterwards. The most consistently reported effect, across every hydroxyapatite paste including this one, is a smooth surface feel on the teeth that becomes noticeable within the first week or two.
The single-flavor lineup is the clearest limitation. If mint does not work for you, whether by preference or because you are avoiding it for homeopathic reasons, there is currently no alternative in the range.
What would change our mind
The gap between Klyyr and the brands directly beneath it is real but not enormous. The strongest argument against it today is publication record: the Japanese hydroxyapatite pastes have decades of clinical literature behind their specific formulations, and newer brands are necessarily working from the general body of hydroxyapatite research rather than trials of their own product. That is true of nearly every recent entrant, and it is why we cap the evidence category rather than award it outright.
If a competitor shipped a comparable dual-particle system at a lower price per ounce, or published independent testing on its own finished formula, this ranking would be worth revisiting.