Porcelain crown to cover severely discolored tooth-preparation

[Sasha59]

How can a dark tooth be masked and prepped so it doesn't discolor the outward aesthetics of a new crown?

My tooth had a root canal over 40 years ago and was shaved down to a peg, and was capped using a porcelain fused metal crown. The underlying tooth is severely discolored and dark. I now need a new crown and my dentist is recommending all porcelain. He is also encouraging me to choose a slightly lighter shade than my surrounding natural teeth to compensate for the discoloration since he is concerned of the possiblity of it showing through. I believe the shade is too bright and want a darker color. Is there anything my dentist can do to prep the underlying tooth, masking the discoloration and preventing it from showing through the new crown? Also, is an all porcelain crown the best option given this circumstance? I do not want another porcelain over fused metal crown as they eventually show dark lines at the gum margin.

For your information, I am having four crowns replaced on tooth numbers 7, 8, 9 (I believe this is the one he is concerned about; both front teeth have root canals but one was repaired using a metal post) and 10 due to severe gum recession and metal leakage. All are currently capped with porcelain over fused metal.

 

[MattKW]

The best way is to take intra-oral photos before preparing the teeth so they can be matched against your other natural teeth. In your case, a photo after the preparation a photo should be taken so the lab can see the colour of the underlying tooth structure.
The porcelain fused to metal (PFM) crowns are the deepest preparation for crowns, so the lab will have plenty of thickness to help disguise the colour, and should just lay down an opaque layer to start. You shouldn't take away more tooth structure!
If your dentist communicates this to the lab with words and photos, it should all go easily. And assuming they're at least a decent lab.

 

[Sasha59]

The best way is to take intra-oral photos before preparing the teeth so they can be matched against your other natural teeth. In your case, a photo after the preparation a photo should be taken so the lab can see the colour of the underlying tooth structure.
The porcelain fused to metal (PFM) crowns are the deepest preparation for crowns, so the lab will have plenty of thickness to help disguise the colour, and should just lay down an opaque layer to start. You shouldn't take away more tooth structure!
If your dentist communicates this to the lab with words and photos, it should all go easily. And assuming they're at least a decent lab.

Thank you so much for your reply. Please know I do not want a porcelain fused to metal crown but instead want all porcelain so would the lab still lay down an opaque layer to start?

 

[MattKW]

Sorry, some ambiguity in my wording. I meant that since you have an existing PFM, then you will have plenty of space for a good porcelain crown. the porcelain crowns need less tooth drilling than a PFM. So in your case, the extra deepness has already been achieved by the previous crown.