Amalgam filling are made by combining elemental mercury, silver, tin, copper and possibly other metallic elements.  Although amalgam filling are still considered to be safe the concerns that was  raised were about the mercury content in amalgams.  However the mercury when combined with the other metals is renders stable and safe for use in fillings.

Amalgam fillings are the most thoroughly researched and tested restorative material among all those in use today. They are durable, highly resistant to wear and they are the lower cost filling option. Amalgam filling are well tolerated by most people with only rare occurrences of allergic response