Dental Amalgams

       The most common question/concern involving any dental material arguably deals with dental amalgams. We most often hear these types of questions:

"Are they safe?"

"Don't they have dangerous amounts of mercury in them?"

"Can they cause cancer?"

"Is there a way to make them the same color as my tooth?"

       These are just a few, but we will try to cover the entire range of concerns regarding dental amalgams to help you make an informed decision. If you were to ask us a question about dental amalgams (metal fillings), we would always have the same answer, "They're great!"

A brief introduction....

       Amalgam is said to have been first used in dentistry as early as 659 A.D. in China and since then has seen leaps and bounds in progress regarding the properties and chemical makeup. A common misconception is that dental amalgams cause cancer. A more accurate statement is that mercury can impair neural function and cause dementia. The mercury contained in dental amalgams mainly presents itself in the form of a vapor that is slowly released over time. In a study conducted by the WHO (World Health Organization) the average daily mercury vapors inhaled by an adult with amalgam fillings was 1.7ug, or 1.7 thousandths of a gram. Relatively speaking, this is only 1% of the upper limit (limit at which levels becomes unsafe) the WHO had set standards for at 300-500ug/day. That is also significantly lower than the 50ug/day maximum they set for safe workplace levels. The sum of all this is that the levels of mercury vapor being emitted through your amalgam filling is minimal compared to the amount you are exposed to in your natural everyday setting. To put things into perspective, a 6 ounce can of tuna contains on average ~53ug of mercury. Now we can't really compare ingested mercury to inhaled but you can begin to see a general trend in exposure levels.

So is it safe??

       Yes. As of July 2009 the FDA released a final statement categorizing dental amalgams as a class II medical device among the likes of gold, composite (tooth colored) fillings, powered wheelchairs and surgical drapes. In a statement from the agency:

"While elemental mercury has been associated with adverse health effects at high exposures, the levels released by dental amalgam fillings are not high enough to cause harm in patients."

Why choose amalgam?

       At this pont, if you are convinced amalgams are safe, why would you choose to have a metal colored filling in your mouth when you can have a tooth colored composite filling? Amalgam (metal) fillings are generally stronger and tend to seal a tooth better. When removing a cavity you are left with a hole in your tooth where the bacteria decayed and ate away your tooth structure. Now all that is left to do is fill that hole, hence a 'filling.' Amalgam restorations tend to seal off the edges of that hole better, making it harder for bacteria to infiltrate again and cause another cavity, recurrent decay. This ability to adapt to the margins of the restoration make ideal further back in your mouth where it is harder to clean and most food ends up. On the other hand, composite restorations generally have a harder time maintaining a good seal and will often exhibit signs of staining and/or recurrent decay after a few years. The down side of metal fillings is that after many years (~15-20) the edges will tend to break down and the seal will be less effective in protecting the inside of your tooth. This is because amalgam becomes brittle when it hardens and can chip away around unsupported areas.

       In certain cases a tooth is too far compromised or there is not enough structure left for a metal filling. In this scenario the metal properties of amalgam play a critical role in restoration choice. The amalgam filling will expand and shrink (on a very small scale) due to the varying temperatures and cause the surrounding tooth structure, which is not very flexible, to expand also, resulting in microcracks throughout the remaining tooth structure. The end result is that the tooth will become even weaker and eventually break. That is why when there is a large metal filling and very little tooth structure the best option is to put a crown on that tooth.

       From an esthetic standpoint, putting amalgams in the posterior portions of the mouth is advisable. It is rare that anyone would notice these fillings in normal day to day interactions. Overall, the advisable option in restoring posterior teeth is still an amalgam filling in most cases.