I could be wrong, but I really don’t think permanent loss of sensitivity is anywhere that high. Though it sounds low for temporary loss, but then it goes away after a couple of hours or so.
It can really depend on how badly impacted the wisdom teeth are. There's apparently a lot of nerve bundles around the back of the jaw bone. If they really need to dig in there to get it out there's a risk. I've had multiple dentists talk to me about my wisdom teeth and all have talked about there being some significant risks with mine.