June 10, 2020
Silver/mercury amalgam fillings have been around since the mid 19th century. As they were being proposed, doctors who treated many ailments with mercury were being shown to be charlatans and their reputations spilled over onto the new filling material. Mercury was referred to as quick silver and the proponents were often referred to as “Quicks” which, when the lack of evidence of effectiveness became apparent, became “Quacks”. Meanwhile, in dentistry, by the 1890’s the debate over amalgam raged, with G.V. Black, the father of modern dentistry in the United States, being the foremost proponent of the material. Known as the “Amalgam wars”, his opinion eventually prevailed and silver amalgam became the standard treatment for almost a century.
The original formula consisted of silver, mercury and tin mixed by hand with a mortar and pestle. With a 75% mercury content, the mixture was placed on a gauze cloth and the excess mercury squeezed out and then the mix was “mulled” in the operators bare palm before placing it in the cavity preparation. Imagine all that mercury exposure to the dentist and staff all day long. It had health effects, including neurological symptoms. Remember the phrase, “Mad as a hatter”? That’s because the people involved in processing felt hats were exposed to mercury compounds as well. Over time, the fillings turned black as they corroded and could stain teeth, even though they held up pretty well as restorations.
In the 1960’s changes began to appear. Amalgam was made in solid pellets and was mixed in a machine with a measured amount of mercury, 45% of the mixture and the need to squeeze out excess and mull by hand were eliminated. Then further refinements in metallurgy had copper added to the alloy and the entire contents were now packaged in sealed capsules. No free mercury was allowed in offices any longer and exposure went down to zero. The copper content prevented the corrosion so the fillings no longer turn black.
While the development of tooth colored composite fillings have made silver amalgam much lessused and less desirable, there are still instances where it is a superior filling option. No scientific studies have shown the limited mercury in the alloy to be of any health concern to either the office staff or the patient. Silver fillings are able to be placed in the presence of moisture and can be placed in bulk rather quickly. This makes them ideal in certain circumstances. Your dental team will always discuss the choice of materials with you before any treatment is initiated.