However, experts do not believe that the levels of mercury exposure resulting from amalgam fillings are of any general health significance. The amount of mercury that reaches the rest of the body is very small. Whether the amount is related to the number of fillings is unclear. Mercury is certainly toxic at large enough doses but the research does not indicate that the small exposures, which result from the use of dental amalgam, are harmful. Many substances are toxic at certain dose levels and for certain people, depending on individual susceptibility.
Some people are even allergic to ingredients in foods such as bread and milk.
Reactions sometimes occur in the soft tissues of the mouth next to fillings, not only with amalgam but with other restorative materials too. Amalgam is not especially allergenic and true sensitivity reactions are very rare. They may resolve spontaneously or after a change of restorative material. It is known that mercury can cross the placenta from mother to foetus and can also be detected in breast milk but there is no evidence of any link between amalgam use and birth defects or still births. Generally, it is sensible to minimize health interventions during pregnancy.