As a european who got dental care in two countries: I never heard of freezing at the dentist! What do they freeze exactly? How does it relate to anestesia?

Medical care seems to have a lot of weird country-specific traditions, e.g. in Hungary it's apparently common to fill small kids' healthy teeth if the groves are too deep so they're simpler to clean and they don't get cavities.

I had never heard of such a thing before moving here, and I genuinely can't tell if it's a brilliant innovation or an insane post-soviet tradition that needs to go away.