Why don't you do silver fillings? Silver or amalgam fillings are 50% silver and 50% mercury. There are also trace metals in that mix . Mixing these two metals creates a stable compound called an amalgam, that can be used to fill teeth. The amalgam being metal, has a tendency to expand and contract, when we eat or drink ,hot /cold foods or liquids. This can cause teeth to become sensitive and cause fractures. We can avoid these complications by using tooth colored resin fillings. They also look much nicer in the mouth.