I had an experience as a child where I _suspect_ my parents and I may have been taken advantage of by a dentist, and this article makes me think that it's not such an improbable thought. Every single time my parents took me for a 6-monthly cleaning, the dentist found new cavities. I'd have to get at least one new filling after each cleaning, sometimes two. We were told this was pretty common because I had braces and wasn't as diligent as I should have been with flossing. My needle phobia was especially bad at the time and every visit was like a nightmare.
When my last cleaning came around, they of course found another cavity. When I was taken in to get it filled, I panicked in fear of the needle and threw up in the chair. They told my mom we'd have to do the procedure on another day. The dental practice did not know that we were about to move to another country, and wouldn't have time to come back. My mom decided to just wait until after the move.
When I was taken to the dentist after moving about the tooth that was meant to be filled, they had no idea what we were talking about. They didn't see anything on the x-rays and said my teeth were fine.
Ever since then I wondered how many of those filling I even needed.
I'd avoided dentists ever since and didn't see one almost 15 years until a couple of years ago when I had a wisdom tooth that needed to be taken out. I was worried that when they'd take a look at my teeth they'd find all sorts of things wrong after all that time. But aside from the wisdom tooth and a tiny cavity that they said could heal on its own, they said my teeth were fine and I didn't need to do anything else except for being better about flossing (which is when I finally got really diligent about it).
(And for the wisdom tooth extraction I specifically found a clinic that specialized in dental phobia. They let me opt for a "Wand" device to do the anesthesia of the tooth instead of a traditional needle. It looks much less like a needle, and the release of the anesthetic is entirely controlled by the device itself and not by the hand of the dentist [though of course the dentist is still the one configuring it]. That somehow made me feel better about the whole thing, since I knew the device would release anesthetic at a stable and "ideal" rate. I trusted it more than a human.)