A dental crown is a tooth-shaped cap that caps off the top of a damaged or decayed tooth. They offer patients the opportunity to restore their smile and chewing function without needing a dental implant or root canal.

Before the crown procedure begins, your dentist will numb the tooth and gum tissue around it. They will then reshape the tooth along its chewing surface and sides.

1. Porcelain Fused to Metal (PFM)

Traditional PFM crowns are durable and aesthetically appealing, and can last for 15 years or more with proper care and maintenance. They protect the natural tooth structure and fill the smile line, while still allowing for some flexability to chewing forces. They have a tough porcelain layer on top that resists fracturing and can withstand a lot of force, but underneath is a metal framework.

The underlying base metal is a combination of various alloys that vary by brand. These base metals include nickel, cobalt, chromium, and titanium alloys. Some crowns are made with noble metals such as gold, which does not corrode and has no allergic reactions, but these are much more expensive.

According to a recent study, PFM and metal crowns have a 5-year cumulative survival rate of 83.9% (Kaplan-Meier analysis). However, some crowns will need to be removed if they experience complications such as root fracture or recurrent decay. This may limit the usefulness of this type of restoration in certain patients.

2. Zirconia

Zirconia is one of the newer crown materials that offers strength and a tooth-like aesthetic. It is biocompatible and doesn’t have a metal substructure, making it ideal for patients who are sensitive to the presence of metal.

Zirconia can also be milled with great precision using CAD/CAM technology, which minimizes the margin for error and leads to durable crowns that fit well. Unlike porcelain, which can be susceptible to staining and discoloration, zirconia is non-porous and resists stains better.

Solid zirconia is opaque and can only be used in the posterior region of the mouth, but it can withstand high biting forces and wear without damage to natural teeth. It can be paired with translucent porcelain in a process called “porcelain fused to zirconia” (PFZ), which results in a stronger crown that is more visually appealing. PFZ crowns can be made in-office and can often be cemented in place during the same visit. They are particularly suited for patients who have bruxism or heavy canine guidance.

3. Base Metals

Unlike noble metals such as gold or platinum, base metal alloys like nickel, chromium and cobalt are used to create dental crowns. They offer strength and durability. These advantages make them a suitable choice for repairing or restoring teeth outside the “smile zone,” such as posterior teeth that experience greater chewing forces.

A specialized milling machine is then used to fabricate the crown from a solid block of the chosen alloy composition. This process is based on digital scanning or impressions of the tooth, and CAD/CAM software to ensure a precise fit.

The resulting crown has an outer porcelain layer that helps shade match it to the surrounding teeth, and conceal the metallic core underneath. However, this material can chip or crack over time, exposing the metallic margin of the crown at the gumline, which can impact aesthetics. For this reason, porcelain fused to metal crowns are recommended for posterior teeth, and all ceramic or zirconia crowns for front teeth.

4. Ceramic

Unlike metal crowns, ceramic dental crowns are not prone to corrosion. They are also hypoallergenic, meaning they won’t trigger allergic reactions in patients who may be sensitive to certain types of metal.

All-ceramic crowns, which are constructed of a porcelain-like material, offer an unsurpassed colour match and light handling properties that closely mimic those of natural teeth. This allows them to blend seamlessly with the surrounding teeth for a more aesthetically pleasing smile.

The most common type of all-ceramic crown is the IPS e.max crown, which is created using lithium disilicate ceramic glass ingots. This enables them to be pressed or milled for greater strength, while also providing a more visually appealing outer layer. They are characterized by their durability and ability to withstand biting and chewing forces, making them suitable for back teeth. They are also mercury free, which is important for patients with metal sensitivities. They are not as translucent or as light-reflecting as other types of crowns, however.