Having to Call the Dentist to Confirm My Appointment

This new thing where you have to call to confirm that you plan to show up for the dentist appointment you made. If I didn't plan to show up I would let you know. Why do I have to confirm that I do plan to show up? - J.C.

I'll show up at the dentist just like I said
I'm not calling them, I'll just be there instead
Do they no longer trust me?
Are they trying to bust me?
Instruments scare me, but this new drill, I dread