This is a seven page essay that covers the history, science and controversies surrounding dental amalgam, the first modern material used to repair decayed teeth, and still the most commonly placed dental restoration in the world.
Silver Amalgam is the most commonly used material for the restoration of decayed teeth in the world! It is reported that it was first invented in china during the second century, and its formula was recorded in 1505 by Liu Wen-t’ai (100 parts of mercury, 45 parts of silver and 900 parts of tin). It was re-invented in the west in France in 1826 by Auguste Taveau of Paris and consisted of shavings from silver coins mixed with mercury. Prior to that time, attempts to fill teeth had been made using numerous materials, but the most reliable was found to be lead foil compressed into a cavity preparation.
Amalgam in those early days had serious drawbacks since its physical characteristics depended on the exact proportions of silver and mercury, and the mixture often expanded on setting causing the tooth to crack.
Silver Amalgam was introduced into the US in 1833 by two French entrepreneurs, the Crawcour brothers. Due to its mercury content (as well as its other physical drawbacks), it was denounced by a majority of dentists. Their main argument against it was that mercury was known to be poisonous. The belief in the severity of the toxicity of mercury was based upon the toxicity of mercury salts and organic mercury compounds which had been used industrially, especially in the manufacture of hats. The term “mad as a hatter” was coined at that time. One of the primary symptoms of poisoning by soluble mercury compounds is erethism which consists of varying degrees of dementia and bizarre behaviors such as excessive shyness or, alternately, aggression.
The mad hatter in Alice in Wonderland was probably a victim of occupational mercury intoxication leading to erethism. When challenged on a point of fact, a person in those days might joke “If it ain’t true, I’ll eat my hat”. The widespread knowledge of the association between erethism (madness) and people who worked in the hat industry was probably the origin of this threat. Hats were made from felt which was obtained from animal fur. A solution of mercury nitrate (very soluble in water) was used to separate the fur from the pelts. It also aided in making the felt mat together smoothly. Because virtually everyone in those days wore hats, huge amounts of mercury nitrate were used in their production.
Sea of hats: Danbury Museum & Historical Society
Pollution from these old factories still persists even today in the sediments around their foundations. Note that once processed, the mercury in the hats presented little potential for causing mercury poisoning because very few people actually “ate their hats”.
In spite of the recognized toxicity of mercury, why is silver amalgam, which is made with mercury, still in use throughout the world for the repair of teeth? Why does the US government, as well as the governments of all other western countries still permit, the use of silver amalgam for the repair of teeth? And why would the professional dental associations of the US and all other nations still promote the use of amalgam? In order to fully understand, you will have to know a little history.NOTE: Google advertisements are placed on web pages by bots which assess content based on key words. This page attracts some ads which link to sites selling “detoxification” medications and services, most of which make many of the claims which I have debunked here. I allow this type of advertisement so readers can see some of the nonsense they sell.
Prior to the introduction of amalgam into America in 1833, the only materials that had commonly been used to repair decayed teeth were non cohesive “beaten” gold leaf which was first used in the US in 1812 and was very, very expensive due to its excruciatingly demanding technique, and lead plugs (L. Pierre Fauchard, circa 1728). By the early 1800’s, the dangers of lead poisoning were widely known and appreciated. Therefore, prior to the invention of cohesive gold foil in 1855, professional dentistry for the majority of people consisted of extracting decayed teeth and building removable false teeth of one sort or another. Often, the dentures were built directly over the rotted sumps of the old teeth.
In 1855 Robert Arthur invented the cohesive gold foil technique. Gold foil differs from gold leaf in its purity and the method by which its surface is protected from airborne contamination. The technique consists of removing the decay, laboriously refining the shape of the cavity and then literally hammering tiny pieces of cohesive gold foil into the cavity preparation until it is filled. Because of its purity, the pieces of gold foil adhere to each other as the restoration is built up. While the gold foil technique was much faster than using gold leaf, getting a gold foil restoration was still a tedious, expensive and painful procedure. Even so, gold foil became the “gold standard” in mainstream dentistry among reputable dentists. Gold foil fillings were very durable and non toxic. But they were not cheap, and the average Joe still couldn’t afford to see a dentist to have his teeth filled. (Cast gold was not routinely used to repair decayed teeth until after 1907 when the centrifugal casting machine was invented.)
On the other hand, remember that itinerant amateur “dentists” had been repairing decayed teeth with amalgam since 1833. Since only the very wealthy could afford to have their teeth repaired by professional dentists, the less affluent public was used to turning to self taught amalgamists if they wanted to save their natural teeth. They certainly couldn’t depend on professionally trained dentists who mostly ended up yanking their natural teeth (without anesthetics) and building dentures. By 1855 when the cohesive gold foil technique was invented, the public had already had 23 years of experience with dental amalgam, even though it was only available through people who resembled traveling salesmen more than professional dentists. Though the use of cohesive gold foil brought the cost of professional tooth repair into the realm of affordability for upper middle class persons, there were precious few people who fit into this income bracket. When the average person went to a real dentist, he expected an extraction, not a filling. When he wanted to repair a tooth instead of having it extracted, he went to an amalgamist!
Dental amalgam is not especially technique sensitive, as evidenced by the techniques used by the Crawcour brothers. Unlike professional dentists who worked in gold foil, the amalgamists would often just scrape out as much decay as they could in a short time and stuff amalgam into the hole. Even though they left lots of decay in the tooth, the fillings seemed to work reasonably well. (The reason for this involves the biochemical characteristics of the amalgam itself.) After 1855, a visit to a dentist for a gold foil filling involved a long, painful and expensive experience, while a visit to an amalgamist was short, relatively painless (since they would stop drilling when the pain got too intense) and inexpensive.
After the introduction of Coca Cola in 1886 , the demand for affordable dentistry skyrocketed. (See my page on the history of tooth decay for more on why Coca Cola was an important event in dentistry.) The success of the amalgam technique being used by the quacks caused a huge surge in “underground” dentistry, and even the more wealthy dental patients were having amalgam restorations done by quack amalgamists. The increasing competition, therefore, forced professionally trained dentists to reevaluate the use of amalgam. In the process, they discovered to their surprise that NO ONE who had their teeth filled with amalgam suffered from any of the symptoms associated with mercury poisoning.
Many dentists still refused to use amalgam, and they formed the core of the burgeoning anti-amalgamist movement. The arguments between dentists opposed to the use of amalgam to fill teeth and those in favor spilled over into the public domain and became known as the Amalgam Wars. The anti-amalgamists were dentists who were angry, in no small part, because a bunch of amateur shysters were taking away their core business. They wanted to scare the public with horror stories about the dangers of the mercury in the amalgam, but since no one sporting the new amalgam fillings was exhibiting the known symptoms of mercury poisoning, the anti-amalgamists had to rely on horror stories about diseases like diabetes, arthritis, gout, etc. for which the medical profession had no explanation. Unfortunately for the anti-amalgamists, the list of diseases that dental amalgam supposedly caused kept shrinking over the years as the real causes of these diseases were discovered by researchers.
Today the list has narrowed so drastically that the anti-amalgamists must resort to the use of vague symptoms such as frequent headaches, fatigue, anxiety, insomnia, depression, and loss of appetite. These symptoms are extremely common in the population, and can be caused by any number of physical or psychological problems, most notably, simple depression.
While the anti-amalgamists continued to bank on the diminishing returns of their war against dental amalgam, the rest of the dental profession had moved on and accepted dental amalgam as one of the major armaments in the fight against tooth decay. A dentist named G.V. Black (1836-1915- pictured above) finally laid the foundation for the correct formulation and use of the new material and essentially revolutionized the profession of dentistry by standardizing the repair of teeth and making dentistry affordable to the average citizen. He standardized the formula for Amalgam in 1896, mixing components to create suitable expansion properties and setting exact limits on the amount of mercury necessary for its formulation. Prior to Black, dental amalgam had been formulated by hand out of shaved coin silver mixed with however much mercury the dentist felt like using. This mixture often underwent expansion on setting and would crack the teeth. Black had a knowledge of materials science and got the formula right.
Today, silver amalgam is still the most popular tooth filling material in the world. It has been used extensively worldwide for over 200 years, and almost everyone in the industrialized world has at least one or two amalgam fillings in his/her teeth. It is estimated that up to 100 million amalgam restorations are placed in decayed teeth every year.
It is important to remember that There is no known statistical difference in the health status of persons with amalgam fillings compared to those with no fillings in their teeth! This has been shown to be the case in NUMEROUS controlled studies, some of which are presented in this essay. If you are worried about the health effects of your amalgam fillings, read the rest of this essay, and follow a few of the the links.