My Doctor Said He Will Do the Root Canal Without Taking Veneers Off. How Is It Possible?

You can have a root canal on a tooth with a porcelain veneer without damaging the veneer.  A veneer should cover only the outside surface of your tooth.  The access for a root canal is done from the tongue side of the tooth and is very conservative.  This allows for the root canal procedure to be completed without touching the veneer.  The small access hole made for the root canal is then filled with a composite material upon completion of the root canal.  Hope this helps.  

When root canal therapy is needed, a small opening is made in the back of the tooth, and this often can be done without touching the porcelain veneer.  What your doctor is telling you is correct. 

Access to the root on the front teeth can be done from the tongue side, so there should be no damage to the veneers.  After the root canal is completed, a bonded filling to fill in this hole is all that is usually needed.