Dentistry has now been privatised, you have to understand that. I've gone private simply because it is shit if I don't. Last NHS dentist I went to, who i could actually get registered with, was horrific, so I gave up. I overheard my private lot talking to, they said you will only get on the list if you're a relative of an existing patient. Thanks Tory voters, you got what you wanted. Fuck you.
Most dental practices have always been private businesses, just like most GP surgeries. It's been like that for many decades - in fact right back to before the NHS was even started.
My sister works in a dental practice and has done for all her working life - nearly 35 years. They "officially" went private 20 years ago (yes, when Blair/Labour were in power!), but it wasn't "properly" because they kept on their "NHS freebie" patients, i.e. those on benefits, children, OAPs etc. It was only the patients who paid (paid the subsidised NHS rates that it) who they forced to go private, so basically those working! Same waiting room, same dentist, etc. If that wasn't bad enough, if a "private" patient became pregnant, they'd put her back on the NHS list so she didn't have to pay for treatment.
Talk about having your cake and eating it. And just as a reminder, that was 20 years ago under Blair/Labour, so it's absolutely nothing to do with Tories today - it's been happening a lot longer than that.