You can just put hair in your blender today.

I don't think you can blend hair into a paste you can then spread over your teeth.

This is about tooth paste, not a supplement

Toothpaste is not a complicated compound to make.

The question is one of optimization. What size (mechanical) or what type of keratin is most suitable, or do we depolymerize (chemical) it first or let oral enzymes do it..? Is brushing as-is sufficient or do we need a longer dwell time..?

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

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/

You have clearly not dealt with hair and mechanical devices.

https://xkcd.com/1349/

I'm forever unwrapping the beater bar and replacing belts in my vacuums. I don't want to do it in my blender too.