The implant is definitely more expensive. I have dental insurance, and it still cost me something like $1,500 out of pocket for the copay.
It's a much more difficult and actually dangerous procedure, so I don't begrudge that it's almost double what it costs for the bridge. I think we should have single-payer healthcare, and prices should be forced down into a rational range for both, but the implant definitely is reasonably a higher price.
Here's what was involved, and I think you can see why:
1. Visit to the surgeon (and imaging) to have the tooth removed.
2. Healing time, 3 months or so, while the bone recovered and filled in.
3. Visit to the surgeon and imaging to make sure the bone is ready to go.
4. Another visit to the surgeon, imaging, and surgery to implant the base.
5. Another visit to the surgeon to remove stitches and check that the implanted base is in place, not infected, etc.
6. Wait 6 months for healing.
7. Go to the dentist to have a fake tooth made.
8. Return to the surgeon to have them image the base again, and if all is well, do another surgery to open up the base and...
9. Send you to the dentist's office to put in the peg and install the new fake tooth.
So yeah, LOTS more complexity, and mine was simple, since they didn't knock me out. Surgery always carries risks, and full anaesthesia, if you feel you have to go that route, is even more expensive and risky.