"to the tooth" is way over used.
I don't know how many people I have known who are pasta experts because they can pronounce "al dente" and then tell you what it means in English. Everyone is in such a hurry to be gourmet correct that they CONTINUOUSLY undertook all pasta they serve.
There are three degrees of done-ness recognized by most chefs.
1- al dente, "too the tooth" barley done
I will guess that 80% of the fine restaurants I have dined cook pasta firm because they would lose nearly all their clientele in Los Angels or Naples if they served it "too the tooth". Some Italian interpretations of "Al dente" means you have to have teeth to eat it. Old people can't gum it. Somehow this craziness persists... you are getting the finest pasta dishes made with firm pasta, not pasta that you are required to have teeth to eat it.
Exasperated home chef
All pasta experts can pronounce "al dente" but not all those who can pronounce "al dente" are pasta experts. Seriously, it just tastes better a little firm--the degree is highly personal--but once the mostaccioli's in your mouth, it's all yours. And I'd eye-roll anyone who says "to the tooth" with a straight face. Cheers.
Interesting point--many recipes for pasta fresca/ all'uova, like tagliatelle, suggest only a brief cooking, when the point to me of these wonderful fresh pastas is their soft silkiness. Need to make sure they're fully there. Dried tagliatelle or papardelle, usually made without egg, is another thing altogether.
I always thought "al dente" was synonymous with "firm", have always expressed this preference to servers at restaurants, and have never been corrected by a server or other person.
Here is Wikipedia's take on it, to the extent that you trust it: