Sep
I discovered your website this morning and I have a question I was wondering if you could answer.
My daughter’s dentist is recommending she get a gold crown on one of her back molars that recently had a root canal. He said it would conserve more tooth structure than doing a porcelain crown. When researching gold alloys, I noticed there are a wide range of options regarding actual gold content.
The lab her dentist uses has high noble alloys ranging from 50% gold to 75% gold.
Are there any bio-compatibility benefits associated with having a higher gold content in the crown? I’m having trouble finding information on that issue.
Thank you,
Ginny Mayhew
Dear Ginny,
gold crown after root canal
Gold Crown
What excellent questions…what to use after root canal therapy – gold or porcelain crown? Let’s first talk about whether or not the crown is actually necessary? Then I’ll talk about the materials.
Not every root canaled tooth needs a crown…you have options. Back in the day before endodontists used microscopes, the coronal (above the gum-line) part of the tooth was often sacrificed to access the canals of the root leaving very compromised coronal structure in need of a full coverage crown.
These days, due to tooth conserving style technique and technology, my endodontist often uses an opening no larger than a small filling. These teeth could be crowned, but very often, that would be way over treatment.
I’ll say it again, and for those who have ever hemmed a garment, cutting a crown on a tooth is like cutting the garment at the fold line ..it excludes all other options! Especially when placed on a youth or young adult, I avoid them like the plague.
If more (than a filling) protection (coverage) is advised, the final lab-fabricated restoration should be correct and NO more. Onlays are my preference, by far. Margins should remain as close to the biting surface as possible with the exception of including the space of older fillings between teeth.
If an onlay is a viable choice (more likely than not, it is), it may be fabricated of all high noble dental alloy or tooth colored ceramic or resin…all will be tooth conserving and last generally so much longer than a crown. Their finished edges will not only be nicer, but less irritating and more naturally cleanable. They will not be less expensive than a crown because it is the design, not the process or materials that differ.
If l were doing the “if it were my daughter” scenario, all things being equal, and uncomplicated, I would have the canals prepared by the best endodontist, with a microscope, ozone gas in the canals prior to completion, and place a conservative tooth colored lab-fabricated biocompatible resin onlay. This both protects the tooth and provides a nonmetal, strong, bondable (and therefore conservative) biocompatible restoration, easily cleanable that leaves almost every future option open.
If a crown is truly the best option, then, yes, a “gold” crown is more conservative than a ceramic one, especially the “(PFM) porcelain fused to metal” crown type.
Women who spend time looking through jewelry packages for a metal they feel is ok to place on their skin rarely even ask about the metal that will be permanently cemented or bonded onto their teeth and contact oral skin (gingiva and oral mucosa). Given the cost difference and permanence involved, selecting a dental alloy should be at least a conversation. Metal that dental laboratories use for making crowns and bridges are referred to as dental alloys (alloys because two or more metals are combined ‘to improve some quality of the product). This quality could be cost, handle-ability and malleability (to be shaped without cracking), or biocompatibility.
It is probably intuitive that the cost of a dental alloy is inversely proportional to the biocompatibility because that’s what we see in jewelry. In other Words, as the content of noble metal increases (and the base metal decreases) biocompatibility and cost generally goes up.
Dental alloys are roughly divided into three groups: High Noble, Semiprecious and Nonprecious.
Noble alloys need only to have more than 60% noble (Gold, Platinum or Palladium) metals, which leaves up to 40% of their content to be other metals, usually semiprecious, or base). These other metals do contribute to the handling ability of the metal during casting and after casting, but most dentists just want to know the ‘final crown will be accurate, hold up and be inexpensive. Truly, this is a serious list already.
Frankly, most very high noble dental alloys are not the easiest to work with. l have found patients who could tolerate only a high noble alloy exclusively (gold, platinum, palladium), but lab-fabrication can be challenging. These metals are expensive in and of themselves (the lab quotes me the current market price we will be paying).
Another factor that adds to the cost of very high noble alloy restorations is that more alloy is needed for the procedure than just the “crown”. All lost wax casting procedures require a “sprue”. Simply explained, this is the bulk material of which the crown (or jewelry item) is just a small extension of.
Sprues allow the “crown” to be cast completely and to cool properly. A lab may need to purchase twice the noble alloy amount to produce the crown, 50% of which he will only recoup if the lab uses the alloy routinely.This is important when we are talking hundreds of dollars. A strictly high nobel metal crown mentioned may Cost up to $1800.00. Ouch.
Are the metals used in the alloy important?
Although according to the Nil-l and other sources, some of the population is allergic to gold (up to 10%), many more have nickel (~32%), chromium (~6%) and beryllium (3-10%) allergies.
Remember the remaining 40%? l regularly see folks who have fantastic oral hygiene who have long been berated for being responsible for causing the bleeding gums which are actually due to reaction to their dental alloys…not fair.
Ask to view a copy of the actual DENTAL ALLOY CERTIFlCATE your dentists lab uses. It lists the percentages and metals used just like the ingredients on a food label. Or, ask your dentist if they would request an all high noble or holistic alloy.
Hope this helps.
Our best,
Dr. Cynthia