Why Do Amalgams Go Black?

Patient's often ask why their amalgams appear black in the mouth, when they are called "silver fillings". Amalgams, like most metals, will corrode over a period of time. Corrosion, coupled with wear (from chewing!) will often mar the surface of amalgam fillings - this results in a pitted surface. Food accumulates in these pits and deteriorates under bacterial action. The resultant 'stain' leaves the amalgams looking slightly worse for wear and black.

Polishing amalgams after they have been placed can make them stay 'silver' longer. Generally amalgams should be polished no less than 24 hours AFTER they have been placed; as only a completely set filling will have a surface hard enough to polish effectively.

If you have a mouth full of dark amalgams, you can have them polished to bring back that shining silver appearance!

Finishing The Filling

The amalgam above was carved anatomically after packing. Although amalgams do not have to be carved to be functional, I carve and finish amalgams as a matter of habit - they look better and should function better than a flat filling! A provisional, or temporary polish was carried out using fine pumice and the result is the "silver" appearance you see above. The amalgam above should be polished again after 24 hours to give it a high mirror finish.