Metal crowns: Gold alloys and certain base metal alloys can be used for crown fabrication. Base metal alloys consist of cobalt, chromium, and nickel in definite proportions.
Advantages: Metal crowns have good strength and are relatively inexpensive as compared to ceramic crowns.
Ceramic or Porcelain Crowns: Ceramic is a compound of metallic and non metallic compounds. Dental ceramics are the most suitable tooth colored restorative materials. Ceramics are now available in many varieties with varying properties and costs.
Different varieties of ceramic available are:
- IPS empress
- In-ceram spinel
Advantage: They are available in variety of shades similar to tooth colour. So, they provide with excellent esthetics. The presence of crown in mouth is not at all noticeable by others.
Disadvantage: Ceramic is brittle material. So, full ceramic crown cannot be given for posterior teeth because posterior teeth are subjected to high forces of mastication which can lead to fracture of a full ceramic crown.
Porcelain Fused to Metal Crowns: In this type of crown, a coating of porcelain is fused on the surface of metal. By doing this the brittleness of full porcelain crown is overcome by using base of crown made up of metal esthetics are also not compromised by using porcelain on the crown surface which provides good colour matching.
They are most commonly used crowns especially for posterior teeth. For anterior (front) teeth full ceramic crowns are preferred due to superior esthetics provided by them.
Temporary Crowns: They can be made up of:
- Stainless steel
They are used for
- Deciduous teeth because they require less tooth reduction for crown placement and deciduous teeth cannot be reduced to greater extent because of chances of inadvertent pulpal exposure.
- For permanent teeth, after tooth reduction till the time permanent restoration is being prepared in the lab tooth is covered by a temporary crown for its protection.