White coating for biomedical products
11-02-2010, 08:14 AM,
#1
White coating for biomedical products
White coating that is biocompatible and it is abrasion and wear resistant?

I was wondering if anyone has come accross a white coating that is biocompatible and it is abrasion and wear resistant? I know it's a lot to ask... PTFE has the color but it can't survivie the abrazive environment of the application....

Thanks!
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11-02-2010, 02:02 PM, (This post was last modified: 11-02-2010, 02:03 PM by djewell.)
#2
RE: White coating for biomedical products
How white does it need to be? Should it be brilliant white or is an off-white good enough? Could the solution be a combination of a wear resistant coating with teflon impregnation to make the coating white?
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11-02-2010, 02:21 PM, (This post was last modified: 11-02-2010, 02:22 PM by Tamara.)
#3
RE: White coating for biomedical products
Actually it should be off white (the color of teeth), but the coating has to be nickel free though due to the irritation Ni causes in the mouth... How does impregnation work with teflon? Can it be combined with any wear resistant coating?


Thanks!!!
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11-02-2010, 02:41 PM,
#4
RE: White coating for biomedical products
Yes, you could use practically any wear resistant coating and impregnate it with PTFE. The PTFE will fill the "valleys" in the base coating. Eventually, it will wear down to the same height as the particles in the wear resistant coating, at which point, the surface will get quite smooth. Think of it like trying to empty a small cup with a square tipped shovel. You can remove a little bit with the shovel, but most of the contents will remain in the cup.

Alternatively, aluminum oxide can have an off-white color and is very wear resistant. It may not be white enough to look like a tooth.
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11-02-2010, 03:19 PM,
#5
RE: White coating for biomedical products
I am an expert in biomedical coating.

I really needs more background for your ques to be answered.

What substrate (this determins whether ceramics can be applied or not)? How tough/abrasive is the environnment? Is it an implantable device that stays in human body for a long time? Or just a tool?

Dental ceramics (aritificial crowns) are white, safe (inert, so you can call it biocompatible), and pretty wear resistant. They are made of some sort of ceramics, as I recall, containing a lot of alumina and/or zirconia and/or silica.

Pure zirconia/alumina are also white and quite wear resistant.

Additionally, there is no way to predict if a material is wear-resistant or not without knowing the environment/articularing partner. Ultrahigh molecular polyethylene is white and wear resistant when working with polished CrCrMo femoral head; however it is devastating when working a rough surface.
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11-02-2010, 11:45 PM,
#6
RE: White coating for biomedical products
Thanks for your answers!!

The substrate is an orthodontic bracket that goes into the mouth. The material of the bracket is CoCr alloy. The bracket stay in the patient's mouth for up to 2 years.
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11-03-2010, 12:30 PM,
#7
RE: White coating for biomedical products
Then, dental ceramics (sometimes called porcelain) may be a good option. Dental material scientist routinely bond dental ceramics to metals. Google "porcelain crown", "ceramic crown" or similar stuff. One issue may bear in mind is that ceramics and metals have different thermal expansion coefficients, so the "white coating", if ceramic, might debond and delaminate either during/after processing or during use (cycles between 37C in mouth and room temperature when taken out). If that indeed turns out to be a problem, consider add a layer more tolerant of this thermal deformation.
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11-05-2010, 03:02 AM,
#8
RE: White coating for biomedical products
Hi Tamara

Sign0016 to the Surface Engineering Forum.

Good to see pulaunias and djewell helping you out. Off the top of my head (prompted by djewell's post) plasma sprayed high purity white alumina topped off and sealed with a cured white PTFE coating. A bit like a white version of the expensive abrasion resistant non-stick frying pan coatings Rolleyes well a thought, not sure how it would work in practice
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11-05-2010, 03:27 AM,
#9
RE: White coating for biomedical products
Actually a even extremely simple alternative that may worth trying. The other way around to Gordon's idea.

Try coating your bracket with a thick layer of dental polymer (I remember 3M and other companies market UV curing resins for the repair of defects on teeth, it looks almost the same as teeth in color; my mom recently got this in her mouth). I think it should be wear resistant as it was designed for that purpose. It alrady contains some zirconia/silica. If not happy, you can add more.
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11-05-2010, 03:38 AM,
#10
RE: White coating for biomedical products
Thank you all for helping out!!

Porcelan might not be the answer somply because the brckets have a very competitive hight, so adding anything over 10 microns is not appreciatd by orthodontis, but an alumina + ptfe night do the trick...

Thanks! Big Grin
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11-08-2010, 06:33 AM,
#11
RE: White coating for biomedical products
Hello guys....!
Thank you for your useful information.I like this kind of post which tell us much wander full massage..!
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11-09-2010, 08:18 AM,
#12
RE: White coating for biomedical products
How do you plan on applying this to the orthodonic pieces?
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12-21-2010, 11:24 PM,
#13
RE: White coating for biomedical products
Dental Materials Science Liaison regular dental ceramics to metals. "Crown Porcelain," Google porcelain crown "or something similar. A problem can remember is that the ceramics and metals have coefficients of thermal expansion, so that the "white coating", including ceramics, disintegrate and delaminate during or after treatment or during use.
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