Higher education in Norway is free so a dentist starts with much less debt to pay off. Also the income range in general is much narrower here. Mean income for dentists is about 900 kNOK/yr, about 90 kUSD.
I suspect that it's also a question of market forces. A dentist that charged much more for an annual check would simply lose that business as there are plenty of dentists here. And quite likely they would lose any follow up work as well.
The profit margin on treatment is much higher but even that seems cheaper than what some of my US friends say they pay (or their insurance pays). Here's the price list for my dentist. In Norwegian but Google Translate does a good job:
http://www.drammen-tannlegesenter.no/om-oss-priser/priser
They do some cosmetic work as well, I imagine that the profit margins are higher for that.
I have two crowns, both created by an automated process of 3D photography and CNC machine in the clinic (Cerec). The most recent one went like this: I made an appointment to see my dentist at about 8:30 one morning complaining of toothache, she discovered that an old amalgam filling had cracked and taken part of the tooth with it and that the only practical repair was a crown. She then apologised profusely that she didn't have time to do it there and then but could I come back at 13:00 that afternoon? I said yes and by 13:30 the crown had been manufactured, fitted, ground down to an exact fit and I was leaving. The crown was a bit over 5 kNOK altogether, about 500 USD, for half an hour's work. The price has gone up a little since.
None of the work I have done, including the annual check-up, is done by a dental assistant, poorly paid or otherwise. I think that this might be because of the high cost of employing anyone in Norway.