A crown is a type of dental restoration which completely caps or encircles a tooth or dental implant. Crowns can be made from many materials, which are usually fabricated using indirect methods. Permanent crowns can be made from all metal, porcelain-fused-to-metal, all resin, or all ceramic.
1. Metal Crowns
Metals used in crowns include gold alloy, other alloys (for example, palladium) or a base-metal alloy (for example, nickel or chromium). Compared with other crown types, less tooth structure needs to be removed with metal crowns, and tooth wear to opposing teeth is kept to a minimum. Metal crowns withstand biting and chewing forces well and probably last the longest in terms of wear down. Also, metal crowns rarely chip or break. The metallic color is the main drawback. Metal crowns are a good choice for out-of-sight back teeth.
2. Porcelain-fused-to-metal dental crowns
These crowns can be color matched to your adjacent teeth (unlike the metallic crowns). However, more wearing to the opposing teeth occurs with this crown type compared with metal or resin crowns. The crown’s porcelain portion can also chip or break off. Next to all-ceramic crowns, porcelain-fused-to-metal crowns look most like normal teeth. However, sometimes the metal underlying the crown’s porcelain can show through as a dark line, especially at the gum line and even more so if your gums recede. These crowns can be a good choice for front or back teeth.
3. All-resin dental crowns are less expensive than other crown types. However, they wear down over time and are more prone to fractures than porcelain-fused-to-metal crowns.
4. All-ceramic or all-porcelain dental crowns
These crowns provide the best natural color match than any other crown type and may be more suitable for people with metal allergies. However, they are not as strong as porcelain-fused-to-metal crowns and they wear down opposing teeth a little more than metal or resin crowns. All-ceramic crowns are a good choice for front teeth.
Deciding Right Crown To Be Used
For Anterior (Front) Teeth – Full ceramic crowns are the most preferred as they provide best esthetics because of their excellent colour matching properties. But they are expensive. So, because of the cost factor, porcelain fused to metal (PFM) crown can be used on anterior teeth but you have to face some problems with anterior PFM crowns
You have to compromise on esthetics as they do not have colour matching properties as good as full ceramic crowns.
Sometimes the gum line overlying the crown may recede with time leading to exposure of the blackish metal portion of crown at the gum line. Porcelain part of the PFM crown may chip off leaving behind the metal portion.
For Posterior (Back) Teeth – Porcelain Fused to Metal Crowns are the preferred ones because good strength as well as esthetics. Although they have poor esthetics than full ceramic, but back teeth are not much visible so compromise can be done on esthetics for the good strength of PFM crowns.