Q. I’ve had cosmetic crowns placed on my 6 upper front teeth (eye tooth to eye tooth). There were multiple issues and I am having them redone. The issue that I’m faced with now is whether or not to have the back of the crown porcelain or metal. If I go with porcelain, I may need another root canal (they will have to remove more of my tooth to make the back thinner). If I go with the metal, I’m afraid that it will show when I laugh or yawn and that later it may look dark. What would you advise?