After my root canal I received my crown. The Dentist ground down my tooth and fitted a temp crown after a couple of weeks my permeate crown came in and it was placed on my tooth However I have noticed and have asked about the gap between the crown and my gum line. I have a good size gap between crown and the gum line, the tooth has been ground down this area is exposed to everything with the enamel gone but the Dentist said it is correct I don't believe him what do you think?

There should not be a gap at the gumline where food and bacteria can get caught. There is sometimes exposed tooth that is smooth with the crown. If it is sensitive use some Sensodyne for a few weeks.

Thank you,

I am really concerned about the enamel being ground off my tooth I am going to see my dentist in the morning and insist that he fix it. The crown should go down far enough to cover all the ground tooth right.

Yes, if the part of the tooth that is exposed was actually reduced for the fitting of the crown it should have been covered. If you look at the small animated photos on the following page, you will see when a crown is seated, there is some tooth surface left exposed.
The dental crown procedure: What steps are involved when a crown is made for a tooth? (http://www.animated-teeth.com/dental_crowns/t4_dental_crowns_steps.htm)