Wow! Getting more opinions and explanations is definitely a good idea.
I know children respond to medication in their unique way. My oldest, at the age of 4, had four fillings. Our dentist was able to do them (the back molars) without any medication. I was amazed and delighted that they were able to have him be quiet for a while and be confident and okay with the work they needed to do!
I have two other sons who had to have fillings and caps. I got them to the dentist earlier than 4-yrs-old (especially when the youngest wouldn't open his mouth for me!).
I felt the dentist gave me some good advice and explained what exactly he was going to do in such a way that I understood and agreed with.
Personally, I can't stand those who promote the child restraints.
I believe the cap on a baby tooth (or is it a permanent tooth?) is an okay idea because of teeth spacing. I already have orthodontist bills, so I appreciate now the caps my children have had so the teeth alignment and spacing corrections have not been so bad.
Good luck!