Dental amalgam is an alloy that consists mostly of mercury – about 50% – and smaller amounts of other metals such as silver, tin, copper and zinc.
There has never been a time in US history when mercury was not known to be extremely toxic. There has never been a time when there was credible evidence that dental amalgam is safe.
Medical studies from the 1800s onward documented the harm to patients from mercury exposure via amalgam fillings. Dentists who used amalgam were known as “quacks” – slang derived from the German word for mercury, quecksilber.
In 1882, the Ohio State Journal of Dental Science published a substantial article by dentist and physician Eugene S. Talbot on “The Chemistry and Physiological Action of Mercury as Used in Amalgam Fillings.” Dr. Talbot includes a fascinating discussion of the history of amalgam’s use in American dentistry:
From its first application as a filling the better class of dental practitioners waged war against it on general principles; not alone on account of the deleterious effects of the mercury in its composition, but because of its unsightly appearance and demoralizing effects upon the dental profession….
From that time onward the use of amalgam has increased, until now tons are consumed yearly in filling teeth. Dr. Harris, in his opening address to the first class of the Baltimore College of Dental Surgery, in 1840, says: “It is one of the most objectionable articles for filling teeth that can be employed, and yet from the wonderful virtues ascribed to this pernicious compound by those who used it, thousands were induced to try its efficacy.”
At the meetings of the dental societies this subject was spiritedly discussed with strong arguments against its use. The first official act in the matter was the appointment in 1841 of a committee by the American Society of Dental Surgeons to report on the use of lithodeon-mineral paste, and all other substances of which mercury is an ingredient, for stopping teeth. They reported in substance that the use of all such articles was hurtful to the teeth and every part of the mouth, and that there was no tooth in which caries in it could be arrested and the organ rendered serviceable by being filled, in which gold could not be employed. This report was unanimously adopted.
At a meeting of the same society July 20, 1843, the use of amalgams was declared to be malpractice, and a committee appointed to further investigate the subject. They referred the matter to the Medical Society of the county of Onondaga, New York. The report of the medical committee was to the effect that no care in the combination or use of the paste will prevent its occasional bad effects.
In 1845, the Mississippi Valley Association of Dental Surgeons resolved that the use of Amalgam fillings was unprofessional and injurious, and would not be countenanced by its members. The actions of the various societies had very little effect; amalgam forced its way into the offices of the majority of dentists in the country. Many excellent practitioners were expelled, and others resigned from the societies to which they belonged.
In 1850 a resolution was passed unanimously by the American Society of Dental Surgeons to rescind the pledge made by the same society previously. Thus ended the so-called amalgam war. It will be observed that no scientific researches were made to ascertain whether deleterious effects were produced by mercury; the chief object of the disturbance was, apparently, to rid the profession of charlatans and their obnoxious materials.
“I am in possession of numberless cases of poisoning from mercury in amalgam fillings,” he later notes in presenting two representative cases, one from the Dental Register (1872) and one from his own practice. They make for sobering reading, with details all too familiar to those who have suffered from their amalgam fillings or have worked to help people heal from the poisoning.
By the late 1900s, there were thousands of peer-reviewed studies documenting high mercury exposures from amalgam use and common adverse health effects. There are still no credible studies demonstrating that amalgam is safe.
Due to mercury’s continued use in dentistry, dental amalgam has proven to be the largest source of mercury in wastewater. Much of that comes from directly from dental offices, but plenty also comes courtesy of the amalgam fillings that millions of people are living with every day. In fact, it has been estimated that the average person with multiple amalgams – or metal crowns over amalgams – excretes 30 micrograms of mercury into sewage systems each day.
The high environmental costs of mercury are one reason why 140 nations have signed on to the Global Mercury Emissions Treaty, which includes provisions for phasing out mercury’s use in dentistry. Some countries – most notably Norway and Sweden – have already banned amalgam use all together. Others limit its use for women and children. Some governments – like the state government of California – require health warnings to be posted where amalgam is used.
Yet special interests such as the American Dental Association and the pharmaceutical industry continue to spend hundreds of millions of dollars to promote the continued use of mercury and attempt to suppress the spread of accurate scientific knowledge about the harm caused by amalgam. Having profited greatly from amalgam over the years, they have much to lose in the increasingly strong shift to mercury-free dentistry.