‘Amalgam! You don’t still use that stuff do you?’
We often hear this statement from patients. Dental amalgam has been used successfully for over 100 years and has been researched more than any other material. It is commonly referred to as ‘silver fillings’ by patients.
Its main advantages are its strength, durability and resistance to wear which make it a great long term filling choice and of particular use in the molar teeth which take a lot of pressure and wear in chewing. The average life expectancy of an amalgam filling is about 11 years but it is not uncommon to see amalgams that have lasted over 20 years, even 40 years! From a dental perspective, it is very easy to use, cost effective and its benefits are still widely commended in dental schools throughout the world. Despite these facts composite fillings are becoming more popular.
The silver colour is perhaps the biggest issue for patients, because it can often be seen when you laugh and speak- especially if the filling is nearer to the front of the mouth.
Amalgam is also held in by mechanical retention; which means slightly more tooth has to be removed in order to place it properly. By ensuring undercuts in the cavity (the tooth being wider at the base of the cavity than the top) and having locks and dovetails, amalgam ensures that once pushed into the tooth the filling will be prevented from coming out in any direction.
In recent times there has also been some concern over the mercury content of dental amalgam. This has received over enthusiastic media coverage and created much concern. Dental amalgam is actually a mixture of metals (mainly silver, tin and copper) and a little mercury- a known toxic substance on its own. However, during the setting reaction of the amalgam, the mercury combines with the other metals to form a very stable material that is safe in your teeth and in your body- it doesn’t get released over time.
Millions and millions of you are walking round happily with amalgam fillings in your mouth with no effect. The only real concern may be a true allergic reaction which is incredibly rare- only a few cases have ever been recorded. There is no evidence I have seen to suggest that dental amalgam is harmful.
If you are pregnant, because of the ability of mercury to cross the placenta, it is recommended by various government bodies, that you avoid having amalgam fillings placed or removed as a precaution. If you are pregnant, it is preferable wherever possible to defer any dental care until after the birth but if absolutely necessary, dentists can use some of the other materials discussed in this section to restore the tooth.
A diet high in seafood will contain more mercury than that released by a mouthful of amalgam fillings. I have heard it discussed in dental circles, that there is more mercury released into your body from eating a single mackerel (that oily fish which is so good for you!) than having an amalgam filling. I personally find this rather re- assuring. Toxic effects only occur if the amount of a substance- in this case mercury- exceeds the amount that your body is able to eliminate and this isn’t going to happen from the quantity released by dental amalgam fillings- even if every single one of your teeth was amalgam.
Perhaps a greater health issue is the environmental effect of dental amalgam. Whilst most dental surgeries are fitted with specialist separators which are devices to prevent this from getting into the public sewers, dental amalgam still contributes about 1/3 of mercury waste
. Unfortunately, USA law does require surgeries to have these amalgam separators fitted
. To my mind, this is the real issue that dental amalgam presents- at an environmental and community level, not the fact you may have an amalgam filling in your mouth.
Studies into the safety of dental amalgam are extensive and the results somewhat varied. Unfortunately with statistics, case selection and by directing focus, you can almost prove or disprove anything you wish to. The perfect scientific study is almost an impossibility- there are so many variables to consider that it is extremely difficult to draw any firm conclusions. Have a read of some of the articles from the U.S. National Library of Medicine
and you will get more of a flavour for this ongoing debate.
Some of the World’s leading international scientific and health bodies such as the National Institute of Health
, The Food and Drug Administration
and the World Health Organization
have all backed the conclusion that 'dental amalgam is a safe and effective filling material'
The Australian dental association takes what I believe to be the correct approach on amalgam fillings
, stating on available research that 'the use of dental amalgam produces no harmful effects'.