Dental crowns: How long do dental crowns last?
How long can dental crowns last?
It would be reasonable to expect that a dental crown could last between five and fifteen years. Most likely a crown which did only last five years would be somewhat of a disappointment to your dentist. It's probably their hope that any crown they make for you will last ten years or longer. Depending on the environment and forces the crown is exposed to (chewing, biting, accidental trauma, tooth grinding) and how well you keep the tooth to which it is cemented free of dental plaque, a crown can last somewhat indefinitely. Especially one positioned where its cosmetic appearance is not much of a concern.
Why do dental crowns need to be replaced?
There can be a variety of reasons why a dental crown might need to be replaced. Some of them are:
A) The dental crown has become worn excessively.
Dental crowns are not necessarily significantly more resistant to wear than your own natural teeth, nor is it in your best interest that they should be. The ideal dental crown would be one made out of a material that has the same wear characteristics as tooth enamel. This way neither the dental crown nor your teeth would wear the other excessively.
Dental crowns can wear out, especially in those cases where a person has a habit of clenching and grinding their teeth. A dentist will sometimes detect a small hole on the chewing surface of a dental crown in that area where it makes contact with an opposing tooth (meaning a tooth that touches on the crown when you bite). Since the seal of the crown has now been lost your dentist will probably recommend that a new crown should be made, before that point in time when dental plaque has seeped in underneath the crown and has been able to start a cavity.
B) Tooth decay has formed at the edge of the crown.
While a dental crown cannot decay the tooth on which the crown is cemented certainly can. If dental plaque is allowed to accumulate on a tooth in the region where the crown and tooth meet, a cavity can start.
While there can be a lot of variables with this type of situation, the worst case scenario for your dental crown is that in order for your dentist to be able to get at and remove the decay the crown will need to be taken off and replaced with a new one.
C) The dental crown has broken.
Dental crowns can break, or more precisely the porcelain component of a dental crown can fracture. Some dental crowns are made in a fashion where their full thickness is porcelain (all ceramic dental crowns). If this is the case then if the crown breaks it will most likely have broken all of the way through, thus compromising the seal of the crown and necessitating its replacement. Even with a less catastrophic fracture it seems likely that the esthetics or function of the crown could be compromised, thus providing a reason why the crown should be replaced.
Anther type of ceramic dental crown is of the "porcelain-fused-to-metal" variety. When this type of crown is fabricated the dental technician first makes a thin metal shell that fully covers over the tooth, a layer of porcelain is then fused to this metal so to give the crown a tooth-like appearance. In cases where a porcelain-fused-to-metal crown has broken it is almost certainly the layer of porcelain that has fractured off, usually revealing the metal that lies underneath (which is often grey in appearance). While the function and esthetics of the crown may have been compromised, the crown's seal over the tooth has probably not been affected.
Since the seriousness of a dental crown fracture can vary greatly, any crown which has broken should be evaluated by your dentist. Some minor damage might not be of much concern, and possibly remedied by smoothing off the area of the fracture with a dental drill. In other cases the crown will need to be replaced. Only your dentist can make this treatment determination, and only after they have had an opportunity to evaluate your specific situation.
D) The esthetics of the crown have become objectionable.
Some dental crowns are replaced because, from a cosmetic standpoint, their appearance is no longer pleasing. Two situations where the cosmetic aspects of a dental crown can change with time are:
1) The dental crown's edge has become visible and it has a grey appearance.
As time passes the gum line of a tooth on which a dental crown has been placed will sometimes recede. This is especially likely in those cases where diligent brushing and flossing have not been practiced. If enough recession takes place the edge of the dental crown, which was originally tucked out of sight just under the gum line, will become visible. Many times this edge of the crown will have a grey appearance.
Inherent to porcelain-fused-to-metal dental crowns (related to their construction) is the fact that the very edge of these crowns will typically show some darkness (a hint of the grey metal that lies underneath the porcelain). If enough gum recession occurs this dark edge will become visible, thus spoiling the cosmetic appearance of the crown.
2) The color of the dental crown no longer matches its neighboring teeth.
Also related to the cosmetic appearance of a dental crown, there can be times when, as years have elapsed, the color of the crown no longer closely matches the shade of its neighboring teeth. In these cases it is not the color of the porcelain crown that has changed but instead the neighboring teeth have stained and darkened.
There can be two solutions for this situation. The dental crown can be replaced with a new one that more closely matches the current color of its neighboring teeth. Another solution could be to use a teeth whitening process so to attempt to return the neighboring teeth to the color they were when the dental crown was originally placed.
