Amalgam fillings are an alloy made of several metals (namely silver, copper, tin and mercury) and has been used successfully for fillings for over 150 years. Evidence based research concludes there is still no direct evidence that amalgam is detrimental to your health.
However, we are placing less amalgams, not due to safety concerns, but because of the availability of alternative filling materials.
Some advantages of amalgam fillings are greater strength, Less clinic time and a lower costs than composite. Disadvantages include silver grey colour, small amount of mercury and needs 24 hours to reach maximum strength.