Dental Crowns

A dental crown is a tooth-shaped “cap” that is placed over a tooth– to cover the tooth to restore its shape and size, strength, and improve its appearance.

The crowns, when cemented into place, fully encase the entire visible portion of a tooth that lies at and above the gum line.

Permanent crowns can be made from porcelain-fused-to-metal or all ceramic.

  • 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 molars.
  • Porcelain-fused-to-metal dental 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.
  • All-ceramic or all-porcelain dental crowns provide better 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.
  • Temporary versus permanent. Temporary crowns can be made in your dentist’s office, whereas permanent crowns are made in a dental laboratory. Temporary crowns are made of acrylic and can be used as a temporary restoration until a permanent crown is constructed by a lab.
The crowns, when cemented into place, fully encase the entire visible portion of a tooth that lies at and above the gum line.

Key aspects to know.

A dental crown may be needed in the following situations:

  1. To protect a weak tooth (for instance, from decay) from breaking or to hold together parts of a cracked tooth
  2. To restore an already broken tooth or a tooth that has been severely worn down
  3. To cover and support a tooth with a large filling when there isn’t a lot of tooth left
  4. To hold a dental bridge in place
  5. To cover misshapened or severely discolored teeth
  6. To cover a dental implant
  7. To make a cosmetic modification

Preparing a tooth for a crown usually requires two visits to the dentist — the first step involves examining and preparing the tooth, the second visit involves placement of the permanent crown.

At the first visit in preparation for a crown, your dentist may take a few X-rays to check the roots of the tooth receiving the crown and surrounding bone. If the tooth has extensive decay or if there is a risk of infection or injury to the tooth’s pulp, a root canal treatment may first be performed.

Before the process of making a crown begins, your dentist will anesthetize (numb) the tooth and the gum tissue around the tooth. Next, the tooth receiving the crown is filed down along the chewing surface and sides to make room for the crown. The amount removed depends on the type of crown used (for instance, all-metal crowns are thinner and require less tooth structure removal than all-porcelain or porcelain-fused-to-metal ones). If, on the other hand, a large area of the tooth is missing (due to decay or damage), your dentist will use filling material to “build up” the tooth to support the crown.