Porcelain-fused-to-metal dental crowns (PFM’s) are somewhat of a hybrid between metal and porcelain crowns.
When they are made, the dental technician first makes a shell of metal that fits over the tooth. A veneering of porcelain is then fused to this metal (in a high-heat oven), giving the crown a white tooth-like appearance.
Advantages of porcelain-fused-to-metal crowns.
A) They’re strong. – Due to their great strength, PFM dental crowns can make a good choice for either front or back teeth.
As a class, this type of crown would only place second to all-metal in terms of strength and durability. And just like them (and in comparison to some types of all-ceramics that don’t), PFM’s have a very long, well documented history of providing lasting service.
Disadvantages of porcelain-fused-to-metal crowns.
There are some disadvantages associated with porcelain-fused-to-metal crowns (which no doubt your dentist will try to minimize as much as is possible). They include:
A) The “dark line” phenomenon. – The metal that lies underneath the crown’s porcelain can sometimes be visualized as a dark line found right at the crown’s edge. A dentist will usually try to position this dark edge just underneath the tooth’s gum line. But, if a person’s gums happen to recede, this dark line can show, thus spoiling the crown’s appearance.
B) Achieving superior aesthetics can be difficult. – While the cosmetic appearance of PFM crowns can be excellent, they often are not as aesthetically pleasing as all-ceramic ones.
For the most part, this difficulty comes from the fact that the crown’s metal substructure must be masked by covering it with relatively opaque (less lifelike) porcelain. While this requirement doesn’t create a problem in all cases, it often presents challenges and results in aesthetic compromises.
C) Durability. – It’s possible that the porcelain on a PFM crown will chip or break off. (It would generally be expected that a PFM crown would pose less risk to catastrophically crack or break than most all-ceramic types. Of course all-metal crowns avoid this complication all together.)
If porcelain breakage does occur, it’s very difficult to make a lasting repair. The most predictable solution is typically making a new crown. As a compromise, some minor chipping may just be smoothed over or polished.
D) They may wear opposing teeth. – The porcelain surface of a PFM crown can create (possibly significant) wear on those teeth that it bites on or rubs against. (Many types of all-metal or all-ceramic crowns are more bio-compatible in this regard.) This issue might be especially important for people who brux (clench and grind) their teeth.
This potential is greatest in those cases where during placement the crown’s “bite” needed to be trimmed and the crown’s surface was not subsequently re-glazed (treated in a high-heat oven) or at least thoroughly smoothed and polished.
Full Metal Crowns (FMC) may be utilised in cases where the aim is to be conservative with crown preparation.
The non-precious alloy is free of nickel and beryllium which ensures that it is biocompatible. The Yellow Gold is of the highest quality and durability.
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