Supposedly a deep cleaning is when they use novocaine on the inside of your mouth and then dig in with the dental utensils to get plaque and or other horrors from below the gum line out. It's supposed to be god-awful so they only do quadrants.I don't believe it's covered by the insurance but more than once every couple of years. My father said he had a deep cleaning done but that as far as he could tell they didn't go really deep into the gums because he had zero recovery afterwards and no blood or anything so it might just be a marketing tactic to suck more money out of us.
Sounds like money making tactic unless someone has horrible teeth to begin with.
I dated a young woman for a couple of months who didn't take care of her teeth all that well. But she had a deep cleaning and after the doctor was finished with her her mouth was completely destroyed for days. And then the healing started where she started to scab over on the gums and that was pretty gross to look at. I didn't feel bad for her because all she had to do was brush her teeth floss for some reason she wouldn't do it everyday which just blew my mind. We didn't kiss all that much so I never spent much time examining her mouth.