Why is dental care so expensive?

Compared to other medical services, anyway.

I'm currently studying full-time at a university in a field I enjoy, and I've never once had an issue paying for prescription medications/medical appointments. Nor have I ever had an issue paying for my glasses, which I got pretty cheap from Specsavers.

But teeth are a whole other league entirely! I needed braces, but they were so wildly out of my price range that I could only afford them through begging at a local medical trust (to whom I am very grateful)! I also need wisdom tooth extractions, and I am looking at thousands of dollars just to get all of the teeth extracted.

How come dental care is so much more expensive than other kinds of health care, even when it's not just cosmetic?