Amalgam (silver filling) is used to repair decayed teeth. It is made of several metals, principally silver, tin and copper. These are combined , using mercury, into a soft mixture.
A band is placed around the tooth and the mixture is placed into the tooth and compacted as it sets. The dentist carves the new restoration to match the surrounding anatomy of the tooth and it is left to cure fully. This takes approx 10-15 minutes.
It is recommended to not eat for the first hour and to avoid eating on that tooth for a full day!
If you are Interested in more information regarding the use of mercury in silver fillings ask your dentist