People frequently wonder if the mercury in their silver fillings (also called amalgam fillings) could be to blame for various chronic diseases and disorders they might experience.

Some of these diseases and disorders include Alzheimer’s disease, headaches, multiple sclerosis, kidney dysfunction, birth defects, and several neurological disorders.  Others fear they are allergic to the mercury in their fillings.   Some people even go so far as to have all of their amalgam fillings removed “just to be safe”. Here is one such story by Bryanna on the Neurotalk Message Boards that illustrates what I’m talking about:

I know of countless people who have become healthier since removing their mercury fillings. I’ve had patients that could no longer function well enough to go to work and had to be physically helped by someone to just walk from one side of the room to the other. After the proper procedure to remove their mercury was done along with chelation therapy…… these people were well again! I had a middle aged man who had slowly lost the peripheral vision in his left eye. His eye doctor could find no physical reason for the loss of sight. We removed his mercury fillings (following the proper protocol) and some of them had been on his 3 upper left teeth. A few weeks after his final chelation therapy, he calls me to tell me that his peripheral vision had returned completely in his left eye! I’ve had patients who were dealing with thyroid disorders who were able to stop their thyroid meds after their mercury fillings were removed!

Reading stories like these causes people to become unnecessarily concerned that their mercury-containing fillings are harmful.  It is highly unlikely that an amalgam filling does anything other than replace decayed tooth structure.  Neville’s Oral and Maxillofacial Pathology states, “An investigation of patients with concerns associated with their amalgam restorations reveals that most of their complaints can be associated with oral, dental, or medical problems unrelated to the restorations.” While amalgam fillings are not to blame for any major diseases, it is worth noting that allergic reactions do sometimes occur in close proximity to an amalgam filling.  Only 1-2% of all people who are allergic to mercury will in some way be allergic to the small amount of mercury released from amalgam fillings.  There are two types of allergic reactions that occur: acute and chronic.

Acute Allergic Reactions to Amalgam Fillings

Acute allergic reactions to amalgam fillings are extremely rare.  They are estimated to occur once for each million fillings.  When this happens, a sore will usually develop in the mouth on some tissue that comes into contact with the filling, such as the tongue or the inside of the cheek within one day of receiving the filling.  If this occurs, you should inform your dentist as soon as possible to get appropriate treatment.

Chronic Allergic Reactions to Amalgam Fillings

Chronic allergic reactions are less rare.  If you notice a thickening of the tissue on the inside of your mouth, such as on your tongue, it could be a chronic allergic reaction.  If this is the case, it would be wise to make an appointment with your dental provider to discuss your concerns.  An example of this is a case in which a patient had a sore on the side of his tongue for five years.  After removal of the amalgam filling, the sore healed.

Conclusion

To summarize, dental amalgam has proven to be a safe and effective filling material to replace decayed tooth structure.  It has been used for the past 150 years as a filling material and during that time, it has never been implicated to be the cause of any disease, although it can rarely cause allergic reactions.

Earlier this week, I was working with a patient who was having two gold crowns placed over some molars that had previously been restored with amalgam fillings.  He said he had received the amalgam fillings about 30 years ago and they had recently broken, resulting in the need for the crowns.  He asked if 30 years was a reasonable amount of time to expect the amalgam fillings to last.  To be honest, it’s wonderful if an amalgam filling can last that long!

The Average Amalgam Filling Lasts About 12 Years

There have been quite a few studies that have tried to determine how long the “average” amalgam filling will last.  One such study involved a single dentist in Belgium.  The study followed 722 amalgam fillings that this dentist had placed between 1982 and 1999.

This study found that this dentist’s amalgam fillings had a mean lifetime of 12.8 years.  The three most frequent reasons for failure of this dentist’s fillings were the amalgam filling itself breaking, tooth decay developing under the filling, and the filled tooth weakening and breaking.

Another study involved 659 dentists in Finland.  Finland is one of the many European countries that are phasing out amalgam restorations to focus on the more aesthetically-pleasing tooth-colored fillings.  This study concluded that the silver-colored amalgam fillings lasted just under 12 years.  Interestingly enough, both tooth-colored fillings included in this study, composite and glass-ionomer lasted less than five years, and less than four years, respectively.

In 2002, a group of researchers scoured 16 electronic databases, and 36 dental journals to find all of the studies performed on the longevity of different types of restorations.  They found 62 studies dealing with the lifetime of amalgam restorations.  You can find a summary of their findings here.  From these studies, they were able to compile lots of data.  From this data, I put together the graph below which shows the estimate of the longevity of amalgam fillings.

As you can see in the above graph, roughly 80% of amalgam fillings are still in existence 10 years after they have been placed.

What is the Longest an Amalgam Filling Has Ever Lasted?

The professor that taught our amalgam class in dental school last year claimed to have seen amalgam filings that have lasted well over 50 years.  He believes that if amalgam fillings are well-placed they can last a lifetime.  Perhaps there are amalgam fillings that have lasted even longer.

Conclusion

If your amalgam filling lasts over 15 years, you should feel pretty good about it.  Amalgam fillings seem to last longer than alternative materials because they consist of a metal alloy, which by nature is bacteriostatic.  This means that it is very hard for the bacteria in your mouth to live around an amalgam filling because the metal makes them sick.  This makes it harder for another cavity to develop under the amalgam filling, which helps the filling last longer.

As a general rule, all fillings will last longer if they are taken care of with regular brushing and flossing.

Do you have any good stories or experiences dealing with amalgam restorations?  Please leave them in the comments!