I really doubt anyone thinks they're going to be earning 100k+ as a GDP without their own practice.
As someone who is not going to be looking for a job anywhere near london I know that I'm going to have many more patients and much less competition for jobs. From looking up jobs online for dentists and such, dentists with experience in the NHS seem like theyre getting around 70k full time - Which is a great salary, incredible hours and one of the most stable professions. AS muchomungo has said however the Medical/dental field IS NOT the field for making huge money UNLESS you are looking to become more than just a dentist/medic and own many practices and run a business. Contrary to belief on TSR, living in a very good area with a nice house, nice car and being able to send your child to a public school is not the norm...
TL;DR - Dentistry is not going to make you ridiculously rich - you work 9-5 5 days a week, great holidays and at the top of society. But you're not gonna have a ferrari with a mansion