This subject has been talked to death. For every dentist making $500k, there's several struggling to get by in a failing practice they refuse to let go of.
I know of a dentist that takes home close to $800k from a single practice. He is in a severely rural, under-served area with a very low dentist to patient ratio. He goes to the hospital once a week to extract teeth on medicare pedo patients (this one day alone covers his weekly overhead).
He does not live a flashy life. He drives a decent truck, lives in a modest house, but owns a lot of land that he hunts on.
A friend of mine shadowed him before dental school, and I follow him on Dental Town. He is open about his production, and is also openly worried about capacity. He is worried that he can't schedule all of the patients that need his help because he is booked out for a long time. He wants to bring in a partner or associate, or open a second location.
Everyone says if you go practice where you're needed, you'll be successful. He truly believes this and it has paid off for him.