A crown or “cap” completely covers a natural tooth. Crowns can be used to change the appearance of discoloured teeth. They can also be used to effect changes in the shape or alignment of teeth. Crowns are particularly useful for teeth that are heavily filled or markedly discoloured.
Discoloured upper front teeth with old fillings and crowns New crowns on the upper six front teeth
Preparation of a tooth to receive a crown involves reduction of all the tooth surfaces. Impressions are made of the prepared tooth, a shade is chosen and the stump of the remaining tooth is protected by fitting a plastic temporary crown. The crown is made in the laboratory and returned for fitting at the practice about two weeks later.
We work closely with our technicians and where the final appearance is critical (e.g. front teeth) it is often helpful for the technician who makes the crown to be involved in matching the shade and shape of the crown to those of the adjacent teeth. The finished crown can then be “tried in”, both at the practice and the laboratory to verify an exact match before it is finally cemented into place.
Crowns on front teeth can be made of porcelain alone or from porcelain reinforced by a metal substructure.
By building up porcelain in layers of different shades and different degrees of translucency it is possible to make very lifelike crowns. However porcelain is a brittle material and conventional porcelain crowns are prone to fracture. New developments of high strength porcelains have resulted in all-ceramic crowns, which are now almost as strong as the metal-reinforced versions.
Porcelain fused to an underlying layer of metal produces the strongest tooth coloured crowns. These crowns are the best choice for crowning teeth likely to be subjected to heavier loads. This would include back teeth and canines.
For teeth subject to very heavy loads gold is the ideal material for making crowns. Obviously the colour doesn’t match your remaining teeth but this often isn’t a problem at the back of the mouth. People who have very broken down teeth or a marked habit of grinding their teeth are often best suited to gold crowns on their back teeth.