SILVER FILLINGS VERSUS
WHITE FILLINGS
Dental amalgam (silver and mercury filling) has been used in dentistry for over 150 years. It consists of approximately 50% silver and 50% mercury with trace amounts of other metals such as copper and tin. These proportions differ slightly depending on the type of amalgam being used.
This restorative material has a number of important advantages. It is very durable and once placed may last 20 - 25 years. It is easy to work with, inexpensive and offers good insulation for the nerve of the tooth.
Disadvantages primarily centre around the fact that amalgam is not an esthetic-looking material to many people. Another disadvantage and concern that has been expressed is that minute amounts of mercury vapor are released with chewing. Some of this mercury may be absorbed by the body. It should be noted that our bodies also absorb mercury from water, air, food and soil. Following many years of experimentation, there is no scientific evidence that dental amalgam causes any illness. In fact, Health Canada (the government body that regulates the distribution of medical products in Canada) considers it safe and effective for most people. Like many substances, however, there are a small number of people who are sensitive or even allergic to dental amalgam. If this is a concern, it should be mentioned to your dentist.
Health Canada has issued two statements of interest. The first is "Whenever possible, amalgam fillings should not be placed in or removed from the teeth of pregnant women". Mercury is vaporized as old amalgam fillings are removed. This mercury can subsequently be absorbed by the body. As well, mercury does cross the placenta. The second statement recommends that "Non-mercury filling materials should be considered for restoring the primary teeth of children when suitable".
To put all this into perspective, a study was done by D. Jones that appeared in the Journal of the Canadian Dental Association in 1999. This paper suggested that a person would have to have 490 dental amalgam fillings for enough mercury to be released to meet the maximum exposure guidelines.
Finally, caution should be exercised if one decides to haphazardly remove sound amalgam restorations. Much more mercury vapor is released from the removal of these fillings than is released from chewing.
The most popular alternative to dental amalgam is composite resin also referred to as white fillings, plastic fillings or bonding. Over the past 25 years, these materials have been constantly evolving such that today, they are stronger, easier to work with and more esthetic then they have ever been. As with dental amalgam, there are advantages and disadvantages to having resins placed in teeth.
The most advantageous property of these materials is that they are tooth-coloured and as such are available in a wide range of shades to match different shades of teeth. They are thus extremely esthetic, usually completely invisible even when placed on a front tooth.
On the down side, they have only recently been strong enough (both in compressive strength and in insulation ability) to be able to be used in back teeth. These are the teeth that bare the greatest stress from chewing. A composite resin in a back tooth may last 5-10 years. These materials are time-consuming and difficult to work with. As well, they are more expensive for the dentist to purchase. For these reasons, the fee for a composite resin filling is higher than the fee for a dental amalgam filling. Finally, over time, composite resins are prone to secondary decay around their edges.
Other alternatives to fill cavities besides dental amalgam and composite resins are gold and porcelain. The situations for which these materials would be beneficial are more limited. They are very time-consuming to place and thus more expensive. However, they are extremely precise and offer the most superior durability.
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