The term 'silver filling ' is a misnomer as a 'silver
filling' contains 50% pure mercury and 35% silver with the remainder
being made up of copper, tin and zinc. The mercury is the same metal
that has been banned from thermometers in hospitals, schools and
throughout industry because of its toxicity.
These fillings were originally used about 150 years
ago as a cheap alternative to gold - the most common material in
use at the time - which was too expensive for the vast proportion
of the population. Consequently, 'silver fillings' were seen as
the cheap alternative to gold. Even then, there was concern about
the toxic affects of the mercury in the fillings and, although various
dental associations banned its use at the time, economic forces
won the day.
As each 'silver filling ' contains approximately
750-1000 milligrams of mercury, and other metals in the filling
include silver, copper, zinc and tin (1), these fillings would more
accurately be called mercury fillings. 75-80% of all tooth fillings
are of this type (2).
At Dental School we were told that, once the filling
was mixed, the mercury was locked into the filling and would not
escape! Recently the British Dental Association admitted that the
mercury in the filling does indeed escape.