On: Toothpaste made with keratin may protect and repair damaged teeth: study

[andrewflnr]

The article mentioned "extracting keratin". It might be more a chemical than a mechanical process.

[Y_Y → andrewflnr]

You are quite right, seems like there are unbreakable matrices that require chemical action:

https://www.jsr.org/hs/index.php/path/article/download/4787/...

Suitable chemical methods:

https://www.sciencedirect.com/science/article/abs/pii/S01418...

https://pmc.ncbi.nlm.nih.gov/articles/PMC10157874/