Amalgam restorations are popularly known as “silver” fillings, although it usually contains less than 3% silver. It has been used for over 170 years and has been the dominant material used for fillings. But the use of amalgam has been declining over the past few decades due to the availability of alternative restoration materials (e.g., composite resin), as well as the increasing demand by the public of mercury-free fillings...

Mercury vapour, released by amalgam fillings, is inhaled and well absorbed in the lungs, from where it is distributed to the rest of the body. This is an important fact to remember, as the mercury released by amalgam is in this form. It is also mercury vapour that has been responsible for countless cases of poisoning, usually in an occupational environment.

Once absorbed, this form of mercury is lipid soluble (it is dissolved in fatty tissues such as the brain and kidneys), therefore making it possible to cross the blood brain barrier (BBB) and the placenta, thereby accumulating in the brain and in the fetus.

The high mobility of inhaled mercury vapour in the body is assumed to be due to its physical properties as an uncharged, monatomic gas that can readily diffuse through the lipid monolayers of the cell membrane. It is then oxidised by the enzyme catalase and by hydrogen peroxide into I-Hg, to form the two major oxidation states of mercury, mercurous and mercuric ions. If this happens after elemental mercury has crossed the BBB, the I-Hg cannot cross back over the BBB and the mercury is therefore retained by the brain for years.

Excerpt from The Big Dental Lie, 1^st Ed, by Dr Ilona Visser