A crown is a tooth replacement that covers a single tooth, primarily to protect it and to make a potentially damaged tooth look more aesthetic. A bridge is intended to replace several teeth in a row. Crowns and bridges are permanent tooth replacements that extend to the edge of the gingiva. They sit in the material of the tooth so there is no visible border between the replacement and the tooth. Crowns may be made of various different materials such as all-ceramic, zirconium, metal ceramic and plastic. The latter is the material of temporary crowns. Teeth are often chipped off so much that their crown part cannot be used to fix a tooth replacement. Even in this case, however, it is possible to keep the root of the tooth. Following root canal treatment, a post can be glued in the root. The post is very similar to a burred tooth stump. It protrudes out of the root of the tooth and is able to anchor a crown even on a severely damaged tooth.
An all-porcelain crown, also known as full porcelain crown or jacket crown, is completely free of metal. This type of tooth replacement meets even the highest aesthetic expectations. It is very similar to the patient’s original teeth and may be used when the patient has metal allergy. The only disadvantage of an all-porcelain tooth replacement is that its bending strength is not sufficient for a bridge. This means that this material is not suitable for bridges; only a single crown may be prepared from all-porcelain.
Metal ceramic crowns are the most frequently used type of tooth replacement, mostly due to the fact that they are less expensive than all-ceramic crowns. Metal ceramic crowns are colloquially calledporcelain crowns, but they are not fully porcelain. A metal ceramic crown is a porcelain tooth replacement fused on a thin metal frame. Only the porcelain material is visible; it completely covers the metal frame.
The colour of the porcelain is selected with the help of a tooth shade chart so it can be completely matched to the shade of the original teeth. Metal ceramic tooth replacements are long-lasting and robust but they are less aesthetic-looking than all-ceramic and zirconium crowns. As even by choosing the most appropriate porcelain shade, it is not always possible to give a lifelike restoration compared to the original teeth.