I get this question asked fairly regularly. There is a lot of difference in opinion when you ask dentists. So I will write a little bit about my thoughts on the subject.
Silver amalgam fillings have been around for about 150 years. Modern dental amalgams are made up of liquid mercury and a mixture of silver, tin, and copper in powder form. They come in capsules which the dentists mixes together. The metal powder mixes with the liquid mercury and you have about 5 minutes to work with it before it becomes hard.
The benefits of silver amalgam fillings are that they are very strong and long lasting. They typically cost a little less than white colored fillings. The negatives of silver amalgam are that they are ugly, they stain the teeth and sometimes the gums, and that they contain mercury.
There have been many studies done and the general consensus is that dental silver amalgam is safe. The FDA has cautiously said that amalgam fillings are safe for adults and children over 6. It is uncertain of the safety of use of silver amalgam for pregnant women.
White colored fillings are made of a composite resin. Many people believe they are porcelain but this is an error. Porcelain is sometimes used in crowns, onlays and inlays, but not in fillings. The composite resin is made up of a light cured polymer which is soft and sculptable until it is cured with an ultraviolet light. It is then hard and able to be polished. The filling itself does not bond to the teeth so we need to prepare the teeth for the bond. We use a bonding agent to condition the surface of the teeth and then we cure the filling onto the bonding agent. It sounds confusing but it is really simple and forms a fairly strong bond.
The benefits of the composite resin fillings are that they blend in seamlessly with the teeth. They are bonded to the teeth so there tends to be less initial sensitivity. The bond strength can also allow dentists to minimize the preparation of teeth and be more conservative with removing tooth structure. The negatives are that the white colored fillings don’t last quite as long. I also tend to see more recurrent decay under white colored fillings.
In my office I don’t use silver fillings. I only use composite resin. I believe that the benefits of the composite resin fillings outweigh the benefits of silver amalgam fillings. I don’t believe silver amalgam fillings are dangerous but I do believe they will be banned in the not too distant future. Probably for environmental concerns more than anything else.
Sometimes patients will ask me if they should change all their silver fillings to white. My answer in most situations is that you should change them to white as the silver fillings fail. But it doesn’t make sense to me to remove good fillings and change them to white unless you have a good reason to do so.