[Dean Mersky, DDS]

My experience with cast PFMs is that about 75% end up with recession, many with discoloration of the root, gingiva, tooth, or any combination. The oxides necessary to bond porcelain is a major culprit, along with corrosion and the toxic nature of "some" of the components. The latter point was published in 1997 in Germany.

I have electron micro photos of the oxide layer on hi noble and NP. The Au metal has a layer of 1 micron, while the NP has 100 microns.

You might not have had complaints about tissue and NP, and clearly not everyone reacts or reacts the same. But I can promise you that there are reactions, even with other metals. I saw it for about 20 years with a variety. That is why periodontists tell GPs to stey supra ging with cast PFMs.