A Crown is used to protect a weakened tooth, usually one that has had a large filling (more filling than tooth), cracks or has been root canal treated.
These teeth will fracture:
It may take weeks, months or years, but it is always better to anticipate breaks in cracked teeth, rather than waiting for it to happen.
Sometimes a tooth can fracture in a way that cannot be repaired.
A crown is like a bucket on a sandcastle, your tooth is prepped so the crown sits over your tooth. They can be gold, porcelain fused to metal or just porcelain. The type of crown needed would depend on vulnerability and visibility.
A gold crown is self-explanatory, although it is actually composed of several metals, including platinum, silver, copper and tin. This is the safest as metal and gold wear about the same as enamel.
A ‘porcelain fused to metal’ crown (PFMs) has a metal shell with a veneer of porcelain fused to it. The metal provides the strength and the porcelain gives it a tooth like appearance.
Full porcelain crowns, in order to be strong enough to work need a lot of tooth cut away underneath ( the more tooth structure that can be kept, the better) therefore we do not recommend these in most circumstances.
An onlay is a partial crown and these are done in gold, they only cover part of the tooth, usually the biting surface and part way down the sides. The less tooth cut away the stronger the tooth is. A good bit of enamel should not be cut down just to make the crown prettier. An experienced dentist will be able to judge the right amount of preparation a weak tooth will need.