Parts of teeth damaged by caries years were filled with amalgam fillings are, which is actually a mixture of silver and mercury. Amalgam fillings are favored by many dentists because they are mechanically resistant, lasts twice as long as the white version, and are cheaper. On the other hand a large number of dental clinics kicks them out of service, and some dental schools do not teach students how to set them up. Despite this fact, amalgam fillings are in most of the world still considered safe for human health as the most effective restoration of malefic teeth. There are those who argue that mercury from amalgam fillings are harmful to human health, and amalgam fillings are considered causes of various diseases, including cancer, multiple sclerosis, rheumatoid arthritis, fibromyalgia, depression. As for depression, thay say that the amalgam fillings are partly to blame for the suicide of dentists. Of course, those who already have them in the teeth suggest replacing the white fillings.