Crowns: Common Materials Used for Making Dental Crowns
Crowns are used for restoring teeth that have been damaged or diseased, and essentially they protect and extend the functionality of your challenged teeth, or to cap implants. Most dentists tell patients their dental crowns will last from 5 – 15 years, even though many remain functional significantly longer.
During a recent research project involving approximately 2,300 porcelain fused to metal crowns (PFM) 85% of them lasted over 25 years, and 95% were still stable after 10 years. Most insurance companies are willing to pay for replacement crowns every 8 years, which is an indicator that they must last at least that long.
Dental crown material options:
Gold tooth crowns are not actually made from pure gold!
Crowns are typically made from gold, silver or other metal alloys, PFM, and ceramic compounds such as zirconia and porcelain for restoring teeth. Crowns are also made to a lesser extent from resin based materials.
Crowns that are made from gold or other metal alloys are considered to be more compatible with your natural teeth. So essentially your tooth or teeth that are capped will be less likely to cause damage or unnecessary wear and tear to the teeth they’re opposing.
Metal alloys are also considered to be more durable than other crown making materials for restoring teeth. Try hitting a metal crown with a hammer and it probably won’t break, do the same to an all ceramic crown and it will shatter. The primary pitfall with metal crowns is their color, as proudly displaying a gold or silver colored front or other prominently placed tooth is not a preference for most people.
Porcelain fused to metal crowns although popular got their name because the porcelain is fused to their metal backing. They provide a natural looking method for restoring teeth, but sometimes the metal beneath the porcelain can create a darkish shade or line at the gum line. To hide the metal an opaque layer of white paint is added to block out the metal. This characteristic flaw makes PFM crowns not as real looking as designs using all ceramic, porcelain or zirconia materials. However, they do offer an element of strength like metal alloys, albeit to a lesser degree, and do offer some of the esthetic qualities of crowns made from porcelain.
One major disadvantage of PFM crowns is they can chip or crack, and since the ceramic is fused to metal they can delaminate completely as a result of breakage. Fortunately, the metal underneath will remain intact, but on occasion it also needs to be replaced.
So not only do they pale in esthetic value with newer materials, the fact that the ceramic can break off makes other crown types a stronger choice for restoring teeth.
PFM’s crowns have become less popular with dentists in recent years, because of the advancements and availability of newer and better options.
Porcelain and ceramic crowns are designed with a finish which has been built up layer by layer. This unique finishing technique is what creates their slightly translucent appearance and similarity to real teeth. They can be designed and colored to match adjoining teeth, and are usually the first choice for the front or other highly visible teeth. At the Westcoast International Dental Clinic’s (WIC), EMAX is the first choice for ceramic crowns, because of its excellent strength and beautiful esthetics. People with metal allergies or who simply prefer not to use metal compounds, find ceramic or all porcelain dental crowns the most viable options for restoring teeth.
How long might your crown last?
Although crowns are one of the most preferred methods for restoring teeth that have been damaged or worn down, they’re not infallible and probably won’t last indefinitely.
As discussed above, some materials such as all ceramics may not last as long especially if used in the back of the mouth. The use of PFM crowns for restoring teeth are literally being phased out, because of their proclivity to characteristic flaws like chipping-cracking-breakage. This trend is accelerating, because the improved material options now available for making crowns aren’t as susceptible to breakage like in the past.
The fact is, the longevity of your crown will be relative to the precision of its fit on the underlying tooth stub, and how well it’s maintained over time. The skill of your dentist and quality of his-her prep work on your damaged tooth, will determine how well your crown fits into its final position. Obviously, the fit quality can vary tremendously and a crown that has been poorly fitted can become a bacterial hot house. The results of inferior workmanship can escalate over time into a more severe situation, potentially leading to tooth decay, gum disease, root resorption or other dire complications.
A misfit is determined when your dentist uses a dental tool called the explorer (a metal pick) to detect an opening or margin of over 25 microns between you crown and host tooth. That maximum margin allows for enough cement too fill the gap which essentially keeps bacteria from creeping into your tooth stub. Unfortunately, only your dentist or an X-ray will be able to reveal if your crown margin exceeds acceptable limits. Keep in mind to preserve your crown you’ll need to maintain optimal hygiene, just like you would for your natural teeth.
The quality of your digital scan or dental impression will be the first indicator of how well your crown will fit. If your dentist doesn’t clearly outline the margin when an impression is taken, this may force the laboratory technician to guess where that crown margin should be. Another problem is often encountered when dental scanners are used, because they’re not as consistent and precise as the margins captured with a deep impression. These miscalculations occur about 25% of the time during the crown design process.
The exacting preparation of the tooth, the quality of impression or scan and the lab’s ability to fit the crown with a maximum 25 microns margin will contribute to its lifespan.
Thank goodness for dental innovations as to this day, using dental crowns remains an integral part of restoring teeth. Whether it’s restoring an existing tooth stub or providing the finishing touches on an implant, crowns are here to stay.
At the WIC’s their patients receive and benefit from an international level service and the highest technological and safety standards practiced in modern dentistry. Furthermore, they’re well experienced in traditional crown procedures and the latest smile design imaging. In most cases they can offer this and more for considerably less than comparable western clinics.
For more information about restoring teeth with crowns and other restoration techniques and procedures, feel free to contact us or stop by one of the WIC’s 4 convenient locations.