A. If the cap is made or covered in porcelain it will not whiten. Supervised Tray whitening by a dentist will advise you on how far you can whiten to blend the old crown with the new shade. the alternative is to whiten the teeth to the lightest shade easily achieved and then replace the crown with a new shade that matches
The StJohns Dental Practice offers free prewhitening assesments. Please contact Amy for details