We had still not found the perfect duvet cover for my daughter Emma’s college dorm room when she went for a routine dental checkup and was told that her wisdom teeth had to come out, A.S.A.P.

She wasn’t having any problems now, but our dentist said trouble could flare up unexpectedly in the middle of the semester, perhaps in the middle of exams, and then she would probably have to leave school to get the teeth pulled. Better to do it now, he said.

Each year, despite the risks of any surgical procedure, millions of healthy, asymptomatic wisdom teeth are extracted from young patients in the United States, often as they prepare to leave for college. Many dental plans cover the removal of these teeth, which have partly grown in or are impacted below the gum.

But scientific evidence supporting the routine prophylactic extraction of wisdom teeth is surprisingly scant, and in some countries the practice has been abandoned. “Everybody is at risk for appendicitis, but do you take out everyone’s appendix?” said Dr. Greg J. Huang, chairman of orthodontics at the University of Washington in Seattle. “I’m not against removing wisdom teeth, but you should do an assessment and have a good clinical reason.”