I had a root canal done 6 years ago which was then filled and a metal crown fixed for my grinder. The crown came off a couple of days ago. My dentist says that the tooth has cracked and he will have to do a root canal again, buildup and then fix a new crown. Is this full procedure to be done as he will be charging me for all 3 works individually.

Why a second root canal? Didn't the first one remove all the nerves? I would think a new build up and crown would be all that would be needed.

The purpose of a root canal is to remove all nerve tissue, before capping. I doubt this has to be done again. Sounds like he is scamming you. Go to another periodontist.