Posts for tag: pfm crowns
A Crown is a Crown, is a Crown ...? NO!
Aren't all crowns the same? What difference does it make what a crown is made of? That’s a very good question!
Since the 1950's, dentists have used Porcelain Fused to Metal (PFM) and full Gold crowns. For the times, being able to crown a front tooth with a PFM and have it look like a tooth was a big deal. The gold crowns were used for the back teeth, as those crowns had been reliable and durable for chewing.
Fast forward to modern dentistry and we have a multitude of choices. I will discuss the differences between PFM, Gold and Zirconia crowns. Strength and durability can be very important, especially on back teeth. Gold crowns are the standard but they don't look like teeth and gold is an added expense. Most patients decline the use of gold crowns. On the other-hand PFM crowns have a thin layer of porcelain on a metal substructure. The thin porcelain layer can chip or fracture which is the most common reason for PFM crown failure. Zirconia crowns are extremely strong, as this type of material is not prone to chipping or fracturing.
Cosmetics are becoming more and more important to patients. Most patients don't want gold crowns, they prefer crowns to look like their natural teeth. Although PFM crowns can be made to look pretty good, they cannot match Zirconia crowns for a truly tooth mimicking appearance.
With PFM crowns, it is not uncommon, especially in cases of recession, to see a grey line at the gum line. The metal substrate of the crown gives a grey shadow. Zirconia being tooth colored through and through eliminates this problem.
To place a crown on a tooth requires the removal of some tooth structure to make room for the thickness of the crown. The amount of tooth structure removal required for a PFM crown is greater than for a Zirconia or gold crown. The thickness of the metal substructure and a thick enough porcelain layer needs to be accounted for. This means much less tooth structure needs to be removed for a Zirconia crown. Less tooth structure removal means less trauma to the nerve of the tooth, making it less likely that a root canal will be needed.
How compatible with the body a material is can be a big concern for some patients. PFM crowns have a metal substructure that can sometimes contain metals such as nickel, silver, beryllium, gold, palladium and others. Some of these metals can cause allergic reactions in some patients. The conduction of electrons from metal to metal can also increase tooth sensitivity. Zirconia on the other hand has no metal, it is an inert material, and it has been shown to be extremely bio-compatible.
Full Zirconia crowns are my restoration of choice. Strength, cosmetics, bio-compatibility, and conservation of tooth structure all combine to make for a great dental material. There are many other materials out there and all have advantages and disadvantages to their use. A frank discussion with the dentist is needed for the patient to make an informed decision for the specific situation.
For my patients, I love Zirconia crowns. That's the TOOTH and nothing but the TOOTH!
If you have any questions that you would like to have addressed, please email Dr. McGuffie at [email protected].