Traditionally, all dental fillings were done with a silver metal amalgam. It was reportedly used as long ago as 7th century China and became a standard dental practice world-wide by the late-19th century. This was understandable, since silver amalgam was cheap, easy to use, and durable.

It was certainly cheaper, and much stronger, than other alternatives such as gold fillings. However, in recent times, dentists have moved to using composite resins because of the potential health hazards associated with metal fillings.

Mercury Fillings

What most people did not know was that dental amalgam also contained a high proportion of mercury, usually around 50 percent. In addition to silver and mercury, it may contain other compounds such as tin and copper, but in smaller amounts. A substantial ratio of mercury is necessary to bind the other elements together into a stable alloy. At the same time that dentistry had adopted the use of amalgam, other medical professionals had become fully aware of the dangers of mercury exposure.

Toxicity

Mercury poisoning normally occurs due to ingestion or breathing the vapors. Mercury ingested from sources such as contaminated fish is known as methylmercury. Vapors can be released in small quantities while chewing food. There’s a possibility that a combination of extensive dental amalgam and high environmental mercury could exceed acceptable risk levels. Mercury tends to stay in the system and accumulate over time.

The effects of mercury poisoning can include nervousness, mood swings, headaches, muscle tremors, weakness, insomnia, and cognitive disorientation. This last symptom was made famous by the “Mad Hatter” character of Lewis Carroll; mercury solutions were once used to cleanse and treat the hides used for popular beaver-skin hats.

In higher levels, mercury poisoning can lead to impaired vision, loss of coordination including speech impairment, memory loss, and eventually to kidney failure and death. In pregnant women, mercury poisoning can also lead to low birth weights and brain disorders of the developing fetus. Some critics also claim that amalgam use has been associated with autoimmune problems such as lupus, multiple sclerosis, and thyroid disease.

The Controversy

Critics were pointing out the dangers of mercury in dental amalgam as early as the 1840s. Even to date, there have been no conclusive studies suggesting that mercury amalgams pose any special threat to human health, either through absorption into the system or vapors during application. However, the vast majority of patients are not even told that the amalgam used in their fillings contains mercury.

The public for the most part is now aware that amalgam is high in mercury content as well as the dangers of exposure to the metal. Public outcry has led to gradually increasing rejection of silver-mercury fillings despite their affordability, especially when there are modern alternatives available.

Other Fillings

The latest and most preferred fillings are made of composite resins. These are fairly cheap and can be blended and tinted to match the color of the tooth so that, unlike amalgam fillings, they aren’t noticeable. Metal fillings also don’t bond perfectly to the tooth structure and can obscure dental x-rays. Their hardness can also create excessive stress on the remaining tooth under high bite pressure. Composite fillings solve all three of these problems.

Gold and gold-alloy fillings are still an option. So are porcelain and glass-based cements. If you’re considering an update to modern materials, gold fillings and appliances can always be resold to a reclamation company that specializes in how to evaluate your dental scrap.

The debate over mercury amalgam goes on, and it’s still widely used. More dentists have shifted to composite resin fillings altogether. To be on the safe side, you might want to discuss the possibilities with your dentist regarding both new and possible replacement of any current amalgam fittings. Ensuring your safety is worth the extra money.