Thank you @hborre: I'm perfectly fine with these settings:

The color chip are almost the same as yours, just +4 in the luminescence.
With my good old Sasha-16, I'm getting this:

Before, with EZTeeth, she had the teeth of a smoker lol

I have also checked the AmbientOcclusion, but actually RTX implementation doesn't support it, and the computing is much, much slower. So: reducing the SSS factor generates less light, hence a slight effect of shadows on the teeth, at least enough for me.

Once again: thank you!