Oil pulling does work to get rid of bacteria and clean your teeth and clean in between your teeth.
But since there's no medical evidence that oil pulling reduces or prevents cavities, prevents gum disease etc dentists do not recommend oil pulling.
It's not a bad thing to oil pull for dental health and can actually help keep your teeth clean and free of bacteria but since there's no medical evidence that it helps and prevents gum disease, cavities etc the American Dental Association does not recommend oil pulling.
So a dentist you go to may tell you about oil pulling but they likely will not but I've never had a dentist recommend oil pulling.
But a lady dentist I go to says that although there's no medical proof that oil pulling works that she personally does it and says it's a good thing.