If i had a root canal and the dr said he could save the tooth but would need to build up the tooth a bit what material would he use, it's dark in colo?

Many: There are many materials available to replace damaged tooth material, most of them very esthetic. Tooth really should be capped after root canal completed.

Restorations: A tooth that has gone through root canal therapy usually requires a crown to be restored adequately. In certain circumstances an amalgam or composite can be used. Since it is up to the clinician, ask your dentist what they propose and why.