Dentists, like GP's actually, are not employed by the NHS, they are contractors. This means that the government/NHS can only tell them what to do during the time that they are paying them...same as if you employ a builder. You have control of the time when you are paying them, not otherwise. For most GP's this is most/all of their time so it looks as though the government can tell GP's what to do. Dentists are exactly the same but usually only contracted to work part time for the NHS and can do what they like with the rest of the time....play golf, sell botox.....offer dental implants....anything they like.