Fillings. For people who have reasonably well aligned wisdom teeth (not impacted, functional teeth), some dentists are inclined to remove them anyway; others to treat any decay which shows up but otherwise leave them alone. Again, this is something where norms differ by country.

Edit: Wait, you’ve had all your _second_ molars removed? That seems very unusual. I’m a little surprised the dentis was willing to do it, unless there was a big problem that couldn’t be dealt with otherwise.