Metal, Porcelain and Zirconia Crowns
Dental crowns, often called caps, are used to surround and support a tooth too severely damaged from decay, cracks or trauma to repair with a conventional filling or bonded restoration. They work much like a thimble protects your finger from a needle. Crowns protect the tooth by covering the complete chewing surface, evenly distributing the chewing forces throughout the remaining tooth structure. At one time the only option to restore a failing tooth was a cast gold crown but there are now many options. The types we use most often are described below.
CEREC Crowns
Beautiful and durable, these one-appointment all-porcelain crowns are made at our Grandville office in our CAD/CAM machine. Northway Family Dentistry introduced this technology to West Michigan in 1998 and has successfully done thousands since then.
Amazingly, a new porcelain, called eMax, was introduced in 2009 and is now even twice as strong. The research and our experience so far is phenomenal. To learn more, check out our CEREC crowns page.
Porcelain Crowns
Like CEREC, all-porcelain crowns are bonded in place and look very natural. Because they are custom made and shade-matched, like veneers, by our world-class ceramist Sandy, they are ideal in the front teeth where esthetics is of prime importance.
Three PFM crowns prepped for bonding.
Porcelain-fused-to-metal Crowns (PFM)
PFM crowns have a porcelain exterior supported by an underlying metal substructure, giving them a much greater strength than porcelain alone. These are frequently a good choice for back teeth. Because Sandy can match these to your smile so well, we still use them in the front when the need for strength demands it. They often leave a slightly dark gum line due to a shadow cast by the metal.
Zirconia Crowns
These crowns have been getting a lot of press lately, mostly because of the trend to eliminate metal from all restorations. Instead of gold supporting the porcelain, zirconia crowns use the strongest porcelain available today as a substructure. Then, a cosmetic layer of porcelain is veneered over, just like in PFMs. Unfortunately, studies have shown that it takes less than 25 percent of the force to break these than it does to break our new eMax CEREC porcelain crowns. Check out these studies if you are interested in more:
Gold Crowns
Truly the gold standard, gold crowns are far and away the strongest because they have no porcelain (glass) to chip. While esthetics is a concern for some, they are still the best option on the back teeth for people with heavy bite problems, especially those who grind or clench.
Compare Your Crown Options
CONVENIENCE |
CONSERVATIVE |
ESTHETICS |
STRENGTH |
|
CEREC |
***** |
***** |
**** |
*** |
Porcelain |
* |
***** |
***** |
** |
Zirconia |
** |
** |
**** |
*** |
PFM |
** |
** |
*** |
*** |
Gold |
** |
*** |
* |
***** |
Convenience
As David Letterman stated so well, no one likes the impressions, temporary crowns or need for additional appointments that you get with lab-processed crowns. Allowing us to skip all these steps and completing them in a single visit clearly is the most convenient.
Conservative
Refers to the ability to preserve tooth structure. By removing less tooth, we have more options available in the future if needed. We also have significantly less tooth sensitivity and nerve damage from the trauma of the drilling, resulting in fewer root canals. Crowns that are not bonded need the sides of the tooth cut down to grab for retention. Bonded CERECs feature the most conservative tooth removal.
Esthetics
The more natural the crown looks, the more esthetically pleasing it is considered. Pure porcelain bonded to the tooth is the most natural looking. Covering the metal with porcelain looks “tooth-like,” but loses the natural translucency teeth have and creates a slight shadow at the gum line. Gold is gold: there is nothing “tooth-like” about it except the shape.
Strength
This is a double-edged sword and more difficult to assess. Dr. John Kois, Dr. Northway's favorite mentor and teacher in Seattle, makes the claim that he “wants the crown to fail, not the tooth.” In other words, while gold is clearly the strongest, it actually has the ability to break the tooth off underneath it. While porcelain is significantly more brittle, it is more likely to break off first and leave the underlying tooth intact.
All this makes choosing the correct material more difficult. A patient with no heavy bite problems should have the most conservative restoration to protect the tooth. However, a patient who grinds severely at night and breaks fillings or porcelain crowns needs gold or PFM crowns, realizing that a failure could cost the rest of the tooth.
If you have a broken or damaged tooth and would like to discuss the right crown for your situation, please contact us today or request a consultation online. We’ll be happy to make the best recommendation for your needs.
