Going for the Gold
Watch O’Brien Implant Specialist and CDT Alex Rugh walk through the process of gold-shading for abutments, and the science behind how it works.
Titanium is the best material for abutments, since it’s associated with fewer biological complications than other materials, and tends to be stronger and more resistant to wear and fracture. But while titanium is an excellent option, it has a small drawback: its natural color is metallic grey, which can show through the crown and gum tissue. We solve this problem in the lab with gold-shading, to make the abutment and prosthesis look more natural.
There are two ways to achieve a gold color on a titanium abutment: anodizing and titanium nitride. Anodizing is a laboratory method to speed up the process of oxidation. When titanium is exposed to oxygen, a layer of oxide forms around the titanium: anodizing adds a thicker layer of oxide than would naturally form. The abutment is loaded into an electrolytic bath and voltage is applied, using a special anodizing machine to create the desired color.
What’s Going On…
Higher voltage creates a thicker oxide layer around the titanium; and as the layer gets thicker, the color changes.
It’s about wavelengths: when light hits the abutment, it reflects once off the titanium and once off the oxide layer. The double reflection means the wavelengths interfere with one another (recall that wavelengths determine how our eyes see color).
The way light reflects off the outer layer depends, partially, on how thick it is —so the resulting color we see changes based on that thickness.
The magnitude of the voltage determines the shade of the finished product.