We have all seen crowns with dark lines above them. This can be caused by a number of things - such as a dark root that has become exposed by gum recession. One thing that can make the gum look dark is the metal that is used to strengthen some tooth-coloured crowns.
The development of ceramic alternatives has helped to overcome some of these problems - this is an exciting area where research and development is producing improved materials all the time. Ceramic crowns offer enhanced aesthetics and have wear characteristics very similar to tooth enamel. They are also becoming much stronger which allows your dentist to use them in more places. They can even be made while you wait, using CAD-CAM technology.
The crowns do not contain any metal - unlike porcelain-bonded crowns- so light transmission through the tooth is more natural looking. Also, because no metal is used, they can get rid of that unsightly grey area at the gum line that is sometimes seen with porcelain-bonded crowns.
The gum tolerates ceramic very well leading to less reaction and so healthier appearance.
Ceramic is not recommended in all situations, but your dentist can advise you.