Crowns are used in dentistry for two reasons: to provide support and protection for a tooth that has been repaired; and, to improve the aesthetic appearance of a tooth. Typically both of those objectives can be achieved when crowns are placed to repair a tooth. Most dental crowns are made of porcelain, but there are other kinds of materials available that have different properties and appearances.
How are Crowns Used in Dentistry?
In dentistry, a crown is a cap that covers the visible surface—that is, the surface above the gum line—of a whole tooth. Putting a crown on a tooth restores its original natural shape so that it looks the same as all of the other teeth in the mouth.
Crowns are usually fitted to complete a repair procedure such as a root canal or filling, or any other kind of procedure that mends an extensively damaged tooth. For instance:
Crowning a tooth that has had a root canal is necessary because the procedure leaves a large hole in the tooth's surface. The repaired tooth needs the support a crown provides, and the crown also provides protection against reinfection.
If a tooth is repaired with a large filling, it may look normal but the repair makes it structurally weaker. Covering the tooth with a crown provides support to hold the tooth together.
What Materials are Crowns Made From?
The most common types of material that crowns are made from are porcelain. Other common materials include gold and PFM, which is porcelain-fused metal.
Porcelain crowns are made from dental-grade ceramic that is engineered to be strong and tough. However, while most porcelain crowns share certain characteristics, they can vary considerably in terms of strength and appearance. This is because some crowns are designed to be “bruxer” crowns and some are designed to be aesthetic crowns.
Bruxer crowns are crowns that are made of heavy-duty porcelain that is formulated for strength and durability. These kinds of crowns are usually used to cap teeth such as molars, as these teeth do most of the biting and chewing and must be able to withstand large amounts of force and pressure.
Aesthetic crowns are made from a kind of porcelain that isn’t as strong as bruxer porcelain, but has a more natural-looking appearance and is easier to match to natural tooth colors. Teeth with aesthetic crowns are more likely to be teeth that are highly visible in the smile zone, but aren’t needed for heavy biting and chewing.
Gold is a highly durable and long-lasting metal. This makes it ideal for crowns, and in fact, gold’s longevity and durability when used in crowns is better than any other crown material. The one thing that makes gold less desirable for crowns is its appearance. Most people don’t like the way gold crowns look and prefer the natural appearance of porcelain. However, for those people who do like the appearance of gold crowns, they also benefit from the increased longevity and strength of the metal.
This kind of crown is made from porcelain fused to a metal frame and combines the best features of both materials. The porcelain is natural-looking and can be color-matched for aesthetic purposes, and the metal frame makes the crown stronger and more durable, and able to withstand more force.
Zirconia is a highly durable material that has a porcelain-type appearance but is actually made from metal. Zirconia crowns can be measured, fitted, and placed in a single appointment, which makes them highly convenient. The potential downside is that some people don’t like the appearance of Zirconia crowns. They have an appearance that’s subtly different from porcelain, as Zirconia is less translucent.
Talk to Your Dentist for Help Choosing Your Crowns
If you have a tooth that is badly damaged—for instance in need of a filling or a root canal—then it’s most likely that your dentist will fit a crown over the tooth after it’s repaired. In these situations fitting a crown is the best way to protect the tooth from future damage, and to return it to its former natural-looking appearance. If you’re not sure what kind of crown material is best, talk to your dentist for advice.