Interference of Ca-EDTA with fluoride delivery in mouthwash

The goal of fluoride mouthwash is to deliver $\ce{F-}$ to the surface of the teeth to turn hydroxyapatite in the dental enamel into fluorapatite.
Typically sodium fluoride or stannous fluoride are used. 


*ACT* fluoride mouthwash also contains $\ce{Ca}$ in the form of $\ce{Ca-EDTA}$. 
[![https://www.drugs.com/otc/114080/act-total-care-anticavity-fluoride-rinse-fresh-min-01.jpg](https://i.stack.imgur.com/F6fVL.jpg)](https://i.stack.imgur.com/F6fVL.jpg)


$\ce{CaF2}$ has a very low solubiliy product of $3.9 × 10^{−11}$, I would expect the $\ce{F-}$ to precipitate as $\ce{CaF2}$ and become unavailable.
This is in agreement with the literature where $\ce{EDTA}$ has been used in the determination of $\ce{F-}$ through backtitration of $\ce{Ca^2+}$. This shows that the complex is less stable than the fluoride.
<http://www.sciencedirect.com/science/article/pii/S0003267000876369>


Note:


It was suggested in the comments to use 10x the concentration of $\ce{Ca-EDTA}$. I don't see how this could work, all it would do is depress the concentration of available fluoride even more.


I suspect $\ce{EDTA}$ is used as an anti biofilm agent or preservative, and the $\ce{Ca}$ is used so it doesn't chelate dental $\ce{Ca}$. I assume this use is unrelated to the process of fluoride delivery.


