I think this is an excellent point. I have had several crowns over the years and my dentist is very aware of proper color match. Is there a material applied to the crown or denture after modeling or is the color dependent upon the color of the 3-D material itself? At any rate, this seems to be an ideal application for 3-D printing and another example of technology being used to benefit mankind. I think it's great. Thank you Ann for posting this piece.
J-allen, Gold is the best metal for implants because it has zero corrosion and absolutly no rejection problems. Stainless steel can have severe corrosion issues in the body, that's why it no longer is used in joints or other critical implants. Many people are allergic to nickel alloys also, even when it is used in jewelry. Have you ever looked at a fitting on a boat or railing and witnessed "stainless Steel" rust stains?
Titanium is another premium medical metal with no rejection or corrosion problems, however if you ever worked with it, it is very difficult to machine. Your average medical lab would have problems with it and would have a steep learning curve.
The article says that in a fully digital operation, impressions are no longer needed. I assume that the patient's mouth would be 3D scanned, correct? If so, what type of 3D scanner would be used for that?
Ceramics do cause a lot more wear on opposing teeth. The main reason they are used is because most people don't want to have a gold front tooth. People want a color matched ceramic (porcelain) for cosmetic reasons. The gold is much less likely to chip and is tougher. I'm not sure of the exact composition of the gold alloy used in crowns but I don't think they are even 50% gold.
j-allen, that's an interesting idea. However, I wonder about the bio-compatibility of some of the alloys you mention, Also, newer alloys have been created specifically for making these dental devices, for example, BEGO's Wirconium: http://begousa.com/Wironium_FAQ.wss
Interesting point. Of course if ceramic materials are not too hard (cause erosion of mating teeth) then i can't see why a metal would be. As for corrosion resistance, certainly any of the high-nickel alloys would be far more than adequate. Even the 300-series stainless steels would be fine. Perhaps I should mention that one reason I avoid gold is for ethical reasons, considering the corrupt, polluting and vicious industries that produce most of it.
The gold used for crowns is actually a very good material. It is very corrosion resistant and best of all it is not too hard. If you make a crown out of a material that is very hard it causes excess wear on the opposing teeth. I would only choose a hard material like porcelain on one of my teeth that is very visible and a color match with adjacent teeth is critical.
Once we have a digital "image" of the crown, I would like the data to be fed to a small CNC milling machine which then sculpts the crown out of a modern corrosion proof alloy such as monel or Inconel. This would give a permanent crown without useng over-priced "squishy" metals. At present we use these precious alloys because they are amenable to low temperature casting, yet they are hardly ideal either mechanically nor economically.
Definitely this seems like a good fit for 3D printing by making a painstaking process more affordable and cost effective. It's good to see the little labs being able to take advantage of the innovation.
Oak Ridge National Laboratory has developed a surface preparation method to improve joining carbon composites with aluminum, with potentially far-reaching ramifications for high-volume industrial applications.
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