Amalgam restorations are better known as "silver fillings." They're one of the most widely used materials to fill cavities in decayed teeth.
You may find online that it's is a highly controversial topic whether amalgams are safe for you to use. Silver fillings contain mercury, which can be very harmful in the high doses. The FDA considers the low dosage received from fillings to be safe for adults and children ages 6 and up.
The ADA, US Centers for Disease Control and Prevention, US Food and Drug Administration, and World Health Organization agree that dental amalgam is a safe and effective material for filling cavities. The Alzheimer's Association, American Academy of Pediatrics, Autism Society of America, and National Multiple Sclerosis Society also are in agreement that amalgam does not pose any health risks to you. Source