This is the second part of Porcelain Fused to Metal Crown.
The metal part of a porcelain fused to metal [PFM] crown is called the coping. As dental students we are required to wax up the full contour of the tooth on a stone replica of the patients tooth. After the full contour has been made the wax is cut back. The portion of the wax that is removed will be filled in later with porcelain. After the wax has been cut back and smoothed it is connected to a wax sprue and invested into stone. The stone hardens around the wax and then the wax is melted out and then cast with metal. The final result is below:
These pictures show the crowns attached to the sprue and the button. They are cut off as seen in subsequent photos.
I took the first few photos without the flash for better contrast of the cut back. Here is the final coping product on the stone model. The metal has been polished. To polish I followed these steps:
1) Remove the crowns from the sprue and use a diamond bur to remove the excess metal.
2) Polish everything lightly with heatless green stone burs. Either avoid the margins or be careful around them. Use them on the cut back area as well.
3) Use brownies on slow speed and just polish the normal contour of the tooth.
4) Inspect the normal contour for any deep scratches. If you find a scratch, repolish it with a green stone and then repolish with a brownie until it shines bright.
5) Polish with a greenie and then an ultra greenie until it has a mirror finish.
Here are the results:
The patient came in and tried on these copings and the fit was perfect. They have been submitted to our in house porcelain lab and should be done in a few weeks. More to come as this case progresses.
