Although the substance used for silver fillings, known as amalgam, has been in use for more than 100 years, the fillings are controversial because of claims that exposure to the vapour from the mercury can cause a variety of health problems ranging from joint pain to multiple sclerosis.
Silver dental fillings are only 30% silver and 50% mercury. Small amounts of mercury vapour are released all the time and increases with chewing or drinking hot foods and beverages. Mercury is also released by the natural process of corrosion and the ageing of the filling. The limited number of published scientific research experiments on amalgam biocompatibility have all strongly suggested that mercury and even the amalgam itself pose potential health problems of sufficient risk to warrant further extensive research.
In 1995 it was reported by researchers in Germany that the amount of mercury in the organs of babies (both born and unborn) correlates with the number of amalgam fillings their mothers have. Most babies in the study were not breast-fed so the researchers conclude that the mercury must have been absorbed via the placenta. Other German research suggests that amalgam fillings may affect fertility.
According to the American Dental Association, up to 76% of dentists use silver fillings containing mercury when filling a tooth.