"anti-extraction-ists" will tell you it's not necessary to remove 3rd molars--because they've never had to remove an infected one in someone too old to have it done when healing potential is high.
My guide: if you can clean it you can keep it. If you can't, take it out when you're young. If you're not young, take it out when it is infected or compromises the adjacent tooth. Simplistic, but safe.