Revisiting Dental Amalgam

AMALGAM ... SILVER OR MERCURY? Dental amalgam has traditionally been called "silver amalgam". More recently many have started naming them "mercury amalgam". Why has there been this change in focus? Amalgam contains approximately 50% mercury and only 25% silver. I believe that the "silver amalgam" term was used to downplay the mercury content in these fillings. Dental amalgam has been the centre of controversy many times in it's more than 150 year history. This controversy has focused mainly on the health risks of mercury. Mercury is a heavy metal and as such is not excreted by the body easily and is in fact stored in body tissues. The medical literature that I have seen is quite clear that this can pose a health risk. The World Health Organization updated fact sheet on "Mercury and Health" lists the following Key Points to consider when thinking about mercury: " Mercury is a naturally occurring element that is found in air, water and soil. Exposure to mercury – even small amounts – may cause serious health problems, and is a threat to the development of the child in utero and early in life. Mercury may have toxic effects on the nervous, digestive and immune systems, and on lungs, kidneys, skin and eyes. Mercury is considered by WHO as one of the top ten chemicals or groups of chemicals of major public health concern. People are mainly exposed to methylmercury, an organic compound, when they eat fish and shellfish that contain the compound. Methylmercury is very different to ethylmercury. Ethylmercury is used as a preservative in some vaccines and does not pose a health risk." Further on in the article they state the following about the use of dental amalgam ... "Dental amalgam is used in almost all countries. A 2009 WHO expert consultation concluded that a global near-term ban on amalgam would be problematic for public health and the dental health sector, but a phase down should be pursued by promoting disease prevention and alternatives to amalgam; research and development of cost-effective alternatives; education of dental professionals and the raising of public awareness." HEALTH CONTROVERSY VS. STRUCTURAL IMPACT: The use of dental amalgam in recent years has been dramatically reduced around the world. I have not placed an amalgam filling in over 20 years. Although I believe that mercury in amalgam (mercury is about 50% of the amalgam of metals ... mercury, silver, copper, tin, and zinc) could have a detrimental health effect, what I have noticed is that teeth with these filling tend to develop cracks and often break over time. Although these fillings are very durable and can last a long time, they do not add strength to teeth but rather tend to weaken teeth over time. The photo at the top of this post shows an extreme yet graphic representation of what can happen as a result of these fillings. If you can picture the behaviour of mercury in a thermometer ... as the temperature increases, the mercury expands and rises up the column. As the temperature cools, the mercury contracts and moves back down the column. In our teeth, the mercury can expand when we eat hot foods. This puts an outward pressure on the remaining walls of the tooth; when we eat cold foods the filling contracts. Over the life time of the filling this slight change in the size and pressure of the filling can cause teeth to weaken and break. I have seen this countless times. As a general rule when the size of an amalgam filling is greater than 1/3 the width of the tooth this effect is much more enhanced. As you can see, however, in the photo above it can even occur in a tooth with a small filling. Tooth coloured fillings bond to the walls of the tooth and help to strengthen the remaining tooth structure. These are great for small to medium sized fillings. In teeth requiring larger fillings traditionally we have placed crowns (also known as 'caps'). Another alternative which preserves more tooth structure and looks beautiful as well is the ceramic onlay. AMALGAM VS. BONDED ALTERNATIVES: Today when we are living longer on average than our predecessors, preserving tooth structure is a good thing. Banking tooth structure for the future is the name of the game. An argument that has been made in favour of amalgam is that it is much more durable than bonded fillings. Based on my years of observation of the destructive effects of amalgam ... many teeth with these fillings break ... even if they are more durable I choose the bonded alternative. I would much rather have my tooth remain in tact and outlive my filling, than I would want to have a durable filling that outlives my tooth after it causes it to break. What do you think? Yours for better health ... Dr. Marty Frankel - Smiles by Design 3030 - 3080 Yonge Street, Toronto, Ontario M4N 3N1 416-770-8526 www.drmartyfrankel.com