The UK has the opposite problem. You don't get overtreated, but you may get undertreated - sometimes it is impossible to find a NHS dentist at all. Indeed, I went private because I literally couldn't find one after my old one sacked me. The private dentists probably have the same problems as described here. But I luckily found a small, nice, ethical one who was recommended by people in town I trust. Literal word-of-mouth still beats any algorithm I know for this kind of question.