The operation is just too slick from a business POV. As someone familiar with SaaS or in general this kind of recurring business model, you can sense all the little operational policies and procedures designed to increase your LTV.
It's a well-oiled machine. Without fail, the hygienist recommends cleaning not once every 12 months or even every 6 months, but every 3 months. When pressed on why, eventually they'll admit it's how nice it feels to have clean teeth and how important your smile is - but NOT strictly necessary for health.
This particular dentist also will shut down and take their entire staff to a resort for a week every winter if the team "hit their targets" for the prior year. That's the literal phrase they used to explain the trip. When I asked what those targets were, the person turned bright red.
So dentistry has a trifecta of factors that will encourage dark-patterns: (1) a true health-related reason for going both preventatively and to deal with problems; (2) a cosmetic / vanity-related reason (white teeth), and (3) the air of higher-educated medical authority.
Wrap that all in a lucrative recurring business model and of course it's going to lead to people taking advantage or at least overpaying for what they really need.
Just writing all this out made me realize I shouldn't be going to my current dentist! Thanks OP. :)